Recent research activities for open and closed cycle MHD electrical power generations are reviewed. World first full scale 500MWe natural gas fired open cycle MHD is now under construction in USSR. Coal-fired open cycle MHD researches are in the stage of proof of concept and retrofitting of old coal power stations with MHD is planned in US and other countries. Basic research for closed MHD is most actively pursued in Japan, which potentially can provide a very high efficiency and a simple and reliable system.

A phosphoric acid fuel cell ( PAFC ) power plant with a capacity of SKW a.c has been constructed for R & D purposes at KIER under a sponsorship of KEPCO. The PAFC power plant has successfully generated an electricity for the first time in Korea. In the paper, the plant configuration and the experimental results ace reported.

This paper describes the efforts to develop an PC based parameter identification system for the D.C. servomotor. The whole identification process of signal generation, measuring, parameter determination is fully automated. To minimize errors due to the ripple component in the measured armature current, digital averaging filter is employed. The proposed parameter correction method using the deadzone current and the time to reach the peak current resulted in excellent agreement between the measured current and estimated current using the model.

In this paper, we describe the optimal driving method and magnetic flux distribution of permanent magnet which enhance torque characteristics in small-sized 3-phase brushless DC motors. The disadvantages of conventional $120^{\circ}$ constant current drive method are torque ripple, switching noise and spike voltage due to the inductance of stator coil. This shortcommings can be avoided by the switching slew-rate of driving current which is called linear voltage driving method. The aim of this study is to analyze linear voltage driving method quantatively and to determine optimal drive current waveform through computer simulation. The selection of commutation angle and slew rate of a new driving current at switching instants makes torque ripple index minimize and average torque maximize. And the validity of this new driving method was assured by Fourier analysis. Considering two dimensional nonlinear magnetic flux distribution on the permanent magnet, we suggest optimal flux distribution according to the presented driving method which improves torque characteristics.

This paper deals with the design method of Superconduting AC Generator(SCG). The establishment of design principle and design procedure of SCG are included in this study. Electric characteristics of SCG, such as synchronous reactance and subsubtransient reactance, are specified first as constraints and the size of SCG is calculated. A 20 KVA with double-shield single-rotor is chosen for case study.

In the case of analyzing electric machinery by finite element method, so far, magnetic current was selected as a driving source. But terminal voltage is a driving source in real systems, and magnetic current is varied according to variation of load conditions. Therfore, in this paper magnetic flux distribution of linear induction motor was analized by using kirchhoff's second law with voltage as a driving source, and magnetic current was calculated.

This paper is analyzed the electrical characteristics of the round solid rotor of turbo-generator without damper cage influence the induction generation modes and the torsional interaction modes of the SSR phenomena, and then examines the problem of representing electrical characteristics which is dependent on frequency and different wedge materials. The basic model of turbo-generator used in the field analysis is viewed as 5-regions of different permeability and conductivity characteristics. The analytical method, which is used in this paper is based on solving a boundary value problem involving 3-D fields, and the basic function consists of the 2-D Fourier series.

In this paper, a short primary-short secondary single-sided LIM which is used as a driving source for automatic conveyor system, is selected as a analysis model. And with a method for analyzing eddy current distribution and thrust force which are produced according to the relative position of primary and secondary, FEM in which current vector potential is introduced is adopted. Also, analysis results are compared with experimental results, so propriety of this at study is proved.

Since the linear step motor(LSM) has the merits which can be controlled the position and velocity by using the micro-computer and has no mechanical transducer such as belt and gear, it's usefullness has been fitted for the printer, x-y plotter, OA machinery and so on. In designing the LSM, we are faced up to the calculation of forces. in this paper, the permeance modeling method suited for the design of transverse flux type linear step motor(TFM) is presented and simulated.

In this paper, the governing equation of each analyzed region of Single-sided Linear Induction Motor was induced from Maxwell's electromagnetic equation. And the linear induction motor was analyzed by finite element method. for calculating inductance, energy perturbation method was applied.

In recent years, Levitated transportation systems have been studied in many countries, Most vehicles used for these systems are driven by linear motors and are levitated magnetically. The magnetic train HDMAG-01 is a proto-type vehicle for low-speed in the range of 100cm/S. This paper presents an outline of the drawing, the testing and its results, describes theoretical models used and compares between computer simulation and test result.

In this paper, We analyzed the End Effect of Single-sided Linear Induction Motor by combination of Finite Element Method in Active region and 0- 1 order Boundary Element Method in Entry, Exit region.

We attempt to achieve both high dynamic performance and maximal power efficiency by means of linear decoupling of rotor speed (or motor torque) and rotor flux. The induction motor with our controller possesses the input-output dynamic characteristics of a linear system such that the rotor speed (or motor torque) and the rotor flux are decoupled. The rotor speed (or motor torque) responses are not affected by abrupt changes in the rotor flux and vice versa. The rotor flux need not be measured but is estimated by the well-known flux simulator. The effect of large variation in the rotor resistance on the control performances is minimized by employing a parameter adaptation method. To illuminate the significance of our work. we present simulation and experimental results as well as mathematical performance analyses.

An adaptive control scheme is presented for uncertain systems whose uncertaintiy bounds are expressed as a linear combination of unknown functions of special form. Both the states and the parameter estimate errors of the closed-loop system are proven to be bounded. The regulation errors can be made sufficiently small by adjusting the design parameters. An application of the proposed method to the position control of a simple pendulum is given.

Optimizing transient response for both tracking reference signals and disturbance rejection is determined by the poles and zeros of the transfer function. Thus, optimal pole assignment and how should weighting matrix for the performance index be chosen is very important to achieve optimum transient response. This paper focus its attention on the choosing and analysis of weighting matrix for optimum pole assignment. Optimum pole assignment is defined for linear time-invariant continuous systems.

In this paper, the LQG/LTR design method is applied of the third order linear time invariant plant model which is the SISO turret-gun servo-mechanism. The dynamic characteristics and the performance of the LQG/LTR controller are analyzed by the computer simulation, and compared with those of PID controller which has been already applied to the turret servomechanism under the sane design specifications.

To track the target trajectory with maneuvers, unknown maneuvering inputs must be estimated. To do this the direct estimation algorithm using generalized least square technique is developed based on the procedure of failure detection and identification(FDI) theory. Through the simulation using maneuvering target scenario, tracking performance and efficiency of the algorithm developed here are investigated.

In this paper, A last time delay damper is presented for HB ( HyBrid ) step motor, which has large oscillation characteristics.The design objective is to develop a cost-effective and good-performance damper that would be applyed to HB step motor / driver system without the addition of transducer that would add a weight, size and cost to the system. The Back EMF signal which is recovered from current and voltage signal is used for the measuring the rotor position. It would be possible to get more accurate delay time for the motor driver system. It is proved that the maximum overshoot can be reduced to 13% at stopping through experiment.

In this paper an engine system model is developed to characterize abd dynamic interactions among various process of engine components in the system utillizing computer simulation. simulation of the dynamics or the entire engine process and emission, including alf-fuel inlet element, intake manifold, combustion unit is carried out.

Recently electronic control of engine is used to satisfy exhaust gas restriction and to increase fuel economical efficiency and acceleration. In this paper, Smith-predictor method is applied to increase control performance for A/F command and disturbance. A/F control performance is simulated by A/F command and disturbance of Chevolet 5.7 liter engine and Toyota 4A-ELU engine. This method can be applied to A/F controller so that lion accurate and rapid A/F control is possible.

In this paper, a mathematical engine model based on the actual engine operation is formulated to be adapted for the evalution and development of engine control system. In the model the classification of fuel paticle siza is considered. The model is simulated through the mathematical interpretation of intake manifold in the rapidly-accerated state. The spark-timing is analyzed with respect to engine r.p.m. The result shows that the model behaves similar performance to the actual engine operation and the spark-timing is very important to the characterization of engine r.p.m..

This work describes the imortance of the load run back control of a thermal power plant which has a serious effect on a power system, and shows the load run back tests results which was carried out at BORONG Thermal Power Plant, finally suggests what control circuits should be modified in the plant control system in order to prevent plant trip in case of auxiliary machine failure.

In this paper, computer control system is introduce for the reheating furnace in the hot rolling process, and in order to support computer control system and process operation, the configuration of expert system application is demonstrated breefly, which is under fine tuning.

The iterative learning controller makes the system output follow the desired output over a finite time interval through iterating trials. In this paper, first we discuss that the design problem of learning controller is originally the design problem of the inverse model. Then we show that the tracking error which is the difference between the desired output and the system output is reduced monotonically by properly modeled inverse system if the magnitude of the learning operator being introduced is bounded within the unit circle in complex domain. Also it would be shown that the conventional learning control method is a kind of extremely simplified inverse model learning control method of the objective controlled system. Hence this control method can be considered as a generalization of the conventional learning control method. The more a designer model the objective controlled system precisely, the better the performance of the approximated inverse model learning controller would be. Finally we compare the performance of the conventional learning control method with that of the approximated inverse model learning control method by computer simulation.

In this paper,an algorithm is implemented to retrieve the control knowledge from the plant being controlled. And this knowledge is stored to the knowledge base and is continuously modified. A control system which realizes this algorithm generates control knowledge automatically and modifies the knowledge base, which was previously generated, in accordance with the experience of input-output relations. And this kind of system can manipulate knowledge by symbolic descriptions. So this system can be used to implement the heuristic procedure which was difficult to realize through conventional procedural computer languages or numerical techniques.

In this paper, we propose a new method of parameter est mat ion which modifies the exponentially weighted RLS (WRLS) method using asliding window. It can be used in adaptive control for a class of linear tine varying system. Computer simulations show that our new method tracts rapidly time varying parameters more effectively than WRLS.

This paper proposes a learning control algorithm for trajectory tracking of large scale system. The controller using only localized informations is composed of stabilizing controller and iterative learning controller. Stabilization and convergence of each subsystem is assured under some conditions which are inequalities of inter-connection terms and learning controller gain.

The optimal control problem of linear Lumped Parameter Systems (LPS) and Distributed Parameter Systems (DPS) is studied by employing the technique of Walsh functions (WF). By the using the elegant operational properties of WF, a direct computational algorithm for evaluating the optimal control and trajectory of LPS and DPS is developed. Without the need of solving the traditional matrix Riccati equation, the WF approach in shown very simple in form and convenient for use of a computer. The approximation is in the sense of least squares employing WF as the basis and the results are in the piecewise constant and discrete form.

In this thesis, a decomposed LQG/LTR controller is designed for an undersea vehicle. The modellig error which results from decomposition of the original model is considered to the design specification for maintaining the robust stability. The LQG/LTR controller designed with new specification is simulated.

This paper presents a DC servo motor controller using self-tuning PID algorithm, which can support Multi-processor for the real time processing. Computer simulation as well as experiment using Multi-processor(8088) are implemented with self-tuning PID algorithm. Presented algorithm is used to compare the performance of the controller with that of the classical PID controller through computer simulation and experiment. The result which use the Self-Tuning algorithm show that motor output follows the reference input trajectory fairly well inspite of load disturbances and parameter variations.

In this paper, a robust controller of state delayed systems is presented. The suggested controller stabilizes the closed loop system independently of the delay time. It is shown that the controller reduces the effect of disturbances on the output of the given system to a pre-specified level. The proposed controller will stabilize the closed loop system in the presence of plant perturbations whose size are less than a pre-specified value.

A digital controller for a discrete-data control system can take many forms. For example, they can be passive RC networks, general purpose digital computers, special purpose of mini-computer, and delay lines. With the recent advent of the microprocessor, its use as a digital controller is evident. This work discusses the hardware and software development of a microprocessor-based digital controller for a discrete-data control system. A second-order, Type 1 system is implemented on an analog computer; a Intel 80-286 microprocessor is used to implemented the controller; and, output response are obtained for step, ramp, and parabolic inputs. The results demonstrate that the microprocessor has potential as a digital controller. Finally, a brief discussion on the results indicate possible areas of improvement of the controller and future investigation.

In resent years, aided by the power and capability of digital computation, the techniques of Walsh Transform have been exploited for applications in commun- ication and signal processing. This paper presents an approach of FWT by using a 16- bit word-length micro- computer. This FWT implements an in-placed decimation-in-sequency algorithm which improves processing speed and memory storage. Several examples illustrate the process and demonstrate the power spectrum of FWT and that of FFT for the waveforms

The electromagnetic suspension system, which is a kind of magnetic levitation, can be categorized into two groups; separate lift & guidance system and combined lift & guidance system. This paper deals with the latter system, in which lift and guidance forces are generated by a pair of staggered magnets with the inverted U- shaped rail. In this work, a rigid body bogie-truck and a twist response type of bogie-truck, which are constructed by two magnetic wheels consist of two staggered magnet pairs, are modeled, and curvature running characteristics of both types obtained by simulation are presented. Simulation result showed that curvature running characteristics of twist response type of bogie-truck is better than that of rigid body bogie-truck.

In the pole assignment strategy, the closed loop poles are placed at prespecified locations. The amount of control effort required is to some extent proportional to the distance of the proposed closed loop locations of the poles from their open loop locations. The poor choice of closed loop locations may result in Large control effort and it may nuke the system unstable. To overcome this problem, pole shift control strategy is described in this paper. The validity of the proposed control strategy is assured through some simulations.

In this paper, a new method of Eye Movement Pattern Encoding (EMPE) which is based on electrooculography(EOG) was suggested for the purpose of effective communication between man and machine, instead of Point-Of-Regard-Selection (PORS) method. Also, ocular interface is designed and the typing aid, eye-pattern writer, was constructed for the test of theoretical validity and its practical aspect. Effect of eye fatigue on the performance of ocular interface was quantified through fatigue test.

This paper describes the AR model of EMG signal during maximum voluntary contraction. By comparing the AR coefficients and the reflection coefficients of the AR model with the median frequency of power spectrum, it if proved that muscle fatigue can be measured by the AR and the reflection coefficients. In the estimation procedure of AR model parameter, the auto-correlation method is superior to the covariance method, and it is determined that the optimal order is six. As the muscle becomes fatigue, the median frequency of power spectrum is declined, and the AR coefficient [$a_1$ ] and the reflection coefficient [$k_1$ ] are also decreased. Therefore the muscle fatigue can be measured by the AR parameter.

This paper describes an algorithm of P-wave detection by significant point extraction method with digital differentiation. P-waves are detected by pattern matching algorithm with significant points. By means of defecting onset and offset points of P-waves, this algorithm can measure the PR intervals exactly which is important to diagnosis the atrial arrhythmia. Because P-wave duration is changed according to heart-rates, we calculate the R-R interval prior to the determination of P-wave duration threshold values in order to actively adapt to the change of P duration The results obtained from the proposed algorithm have defected successfully P-wave almost more than 90%.

A study for the recognition of the Korean characters by a neural network is presented. To reduce the dimension of the input image data, DC components are extracted from each input image and used as input to the neural net. A multi-layer perceptron with one hidden layer was trained with back-error propagation training algorithm. Its performance is tested for 24 ${\times}$ 24 binary images of Korean characters and the results of several experiments are presented.

Optimal Power Flow (OPF) solution by the Newton's method provides a reliable and robust method to classical OPF problems. The major challenge in algorithm development is to identify the binding inequalities efficiently. This paper propose a simple strategy to identify the binding set. From the mechanism of penalty shifting with soft penalty in trial iteration, a active binding sit is identified automatically. This paper also suggests a technique to solve the linear system whore coefficients are presented by the matrix. This implementation is highly efficient for sparsity programming. Case study for 3,5,14,118,190 bus and practrical KEPCO 305 bus system are performed as well.

This study presents a methodology to choose the optimal parameter of controller by using the performance index sensitivity. The pro-posed method is to select the controller parameter to have the minimum sensitivity. It is shown that the optimal parameter proves the effectiveness in the dynamic stability of power system.

This paper presents a fast realistic method based on a P-Q decoupled linearized model for contingency analysis. This method involves new idea to correct the errors caused by neglecting the resistance of transmission lines and/or by linearizing the model. The idea is to use fast correction method of errors by the principle of superposition for compensating these errors. Results demonstrating the effectiveness of the method on 25-bus model system and IEEE30-model system are presented

The sparse vector method is more efficient than conventional sparse matrix method when solving sparse system. This paper considers the structural relation between factorized L and inverse of L and presents a new ordering algorithm for sparse vector method. The method is useful in enhancing the sparsity of the inverse of L while preserving the aparsity of matrix. The performance of algorithm is compared with conventional algorithms by means of several power system.

Voltage collapse is a serious concern to the electirc utility industry. It is common to associate steady-state stability with the ability of the transmission system to transport real power and to associate voltage collapse with the inability to provide reactive power at the necessary locations within the system. An algorithm to directly calculate the critical point of system voltage collapse was presented by the authors. The method (based on the ordinary power flow equations and explicit requirement of singularity of the Jacobian matrix) is basically one degree of freedom with proper load distribution factors. This paper suggests a modified algorithm to increase the degree of freedom, introducing the nonlinear programming technique. The objective function is a distance measure between the present operating point and the closest voltage collapse point. Knowledge of the distance and the most vulnarable bus from the voltage collapse point of view may be used as a useful index for the secure system operation.

A new algorithm is suggested to solve the optimal reactive power control(optimal VAR control) problem. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. The model minimizes the real power losses in the system. The constraints include the reactive power limits of the generators, limits on the bus voltages and the operating limits of control variables- the transformer tap positions, generator terminal voltages and switchable reactive power sources. The method developed herein employs linearized sensitivity relationships of power systems to establish both the objective function for minimizing the system losses and the system performance sensitivities relating dependent and control variables. The algorithm consists of two modules, i.e. the Q-V module for reactive power-voltage control, Load flow module for computational error adjustments. In particular, the acceleration factor technique is introduced to enhance the convergence property in Q-module, The combined use of the afore-mentioned two modules ensures more effective and efficient solutions for optimal reactive power dispatch problems. Results of the application of the method to the sample system and other worst-case system demonstrated that the algorithm suggested herein is compared favourably with conventional ones in terms of computation accuracy and convergence characteristics.

In probabilistic production costing simulation, cumulant method is widely used. But this method have some limitations in some cases. To overcome these serious drawbacks, MONA(Mixture of Normals Approximation) method was proposed. The MONA method uses multiple normals to represent the Equivalent Load Duration Curve. In this paper we investigate the MONA's characteristics by comparing other methods and derive the efficient formulae for MONA. Also, we propose the fundamental algorithm for Mixture of Cumulants Approximation(MOCA) which is the general case of MONA.

The structure of A matrix of one machine connected to the infinite bus is described for a full model. The A matrix can be partitioned to submatrices which depend on the initial operating point and do not depend on it. When the dynamic properties for several different operating points are desired, those submatrices can be obtained through simple column operations. Furthermore, the elements of A matrix car be directly calculated from the manufacturer's data. RMS quantities of the state variables for the initial operating point are used. This approach can save the labor for calculating the elements of A matrix for the dynamic stability analysis.

Direct calculation algorithm for the elements of A matrix is suggested for a single machine connected to the infinite bus. Excitation system and power system stabilizer are included. When A matrix is partitioned into seven submatrices, we can identify the location of non-zero elements and formula for each element. No matrix inversion and multiplication are necessary.

Direct calculation algorithm for the elements of A matrix in multimachine power systems with constant impedance loads has been suggested. Generator's rotor parameters need not be determined from the manufacturer's data. We can identify the elements of A matrix into two categories: One is related to only generator parameters, and the other is related to generator parameters, initial values, and $Z_{Bus}$ matrix.

With the increasing number of power plants in modern electric power systems, power system dynamics studies become more complex. Frequently, only some part of the power system is interesting. So it becomes necessary to reduce the size of dynamics or to introduce the dynamic equivalencing techniques. The major approach of dynamic equivalencing techniques are two: one is coherency approach, which seperates machines in groups and combines machines within each group closely swinging together into one equivalent and the other is modal approach which neglects the fast modes of external system. In this paper, a new dynamic equivalencing approach which seperates machines in coherent groups as the coherency method but doesn't predetermine the structure of the equivalent.

This paper deals with the expert system using network configuration and input information composed of protective relays and tripped circuit breakers. This system has knowlegebase independent on network dimension because network representation consists of the type of the matrix. Therefore, the knowlege of network representation is simplified, the space of knowlege is reduced, the addition of facts to the knowlege is easy and the expansion of facts is possible. In this paper, the network representation is defined to system matrix. This expert system based on the system matrix diagnoses normal, abnormal operations of protective devices as well as possible fault sections. The brach and bound search technique is used: breadth first technique mixed with depth first technique of primitive PROLOG search technique. This system will be used for real time operations. This expert system obtaines the solution using the pattern matching in working memory without no listing approach for rule control. This paper is written in PROLOG, the A.I. language.

This paper deals with the expert system for power system recognition of energized and deenergized system using circuit breaker information. The basic idea is isolating the system with the system matrix representing the system configuration and the states of the circuit breakers. The knowledge base is composed of these isolated systems and decision rules. The isolated system with the sources is recognized as the energized system and the system without the source as the deenergized system. The rules use the system matrix and the the inference scheme is simplified in a great deal. Above all, the overall searching labor of the rules is independent on the system size and it is possible to expand into the real system and the real time restoration can be carried out easily. The expert system is written in PROLOG.

A knowledge based expert system is a computer program that emulates the reasoning process of a human expert in a specific problem domain. This paper presents an expert system to diagnose the various faults in power system. The developed expert system is represented considering two points; the possibility of solution and the fast processing speed. As uncertainties exist in the facts and rules which comprise the knowledge base of the expert system, Certainty Factor, which is based on the confirmation theory is used for the inexact reasoning. Also, as the diagnosis problem requires the inductive reasoning process in nature, the solution is imperfect and not unique in general. So the expert system is designed to generate all the possible hypothesis in order of the possibility and also it can explain the propagation procedure of the faults for each solution using the built in backtracking mechanism. In realization of the expert system, the processing speed is greatly dependent upon the problem representation, reasoning scheme and search strategy. So, in this paper the fault diagnosis problem itself is analysed from the view point of Artificial Intelligence and as a result, the expert system has the following basic features. 1) The certainty factor is adopted in the inference engine for inexact reasoning. 2) Problem apace is represented using the problem reduction technique. 3) Bidirectional reasoning scheme is used. 4) Best first search strategy is adopted for rapid processing. The expert system was developed us ing PROLOG language.

Owing to the rapid development of economy and the higher living standard of people, electricity demands have growth and the peak load has been increased rapidly. To cope with this impacts and to reduce the cost of service,utilities are conserned about power load management program. This paper shows a scheme of power load control and the basic structure of direct load control system. And also radio control method using the public pager which is one of the best economical and serviceable method in techniques will be introduced briefly.

The Battery Storage System (BSS) has been used in foreign country for Load Levelling, Flicker Compensation, Load Frequency Control, etc. because it has easy application characteristics compared to the other storage system such as the Pumped Hydro System, Compressed Air System, etc.. In this paper, the application field and available capacity of BSS is outlined in Korea.

Battery Energy Storage System has been studied and adopted actively by foreign advanced utilities, in order to utilize off peak energy. The outline of 20KW Battery Storage System design of the project - the study on the development of Battery Electric Energy Storage System, carried out by KERI KEPCO, is presented. The first target of this project is the conceptual design of MW-class Battery Storage System and 20KW Battery Storage System is its the small scale system.

This paper presents a new algorithm of the operation on power distribution system by automated distribution system (ADS). A performance of this automated algorithm is established to operate the distribution system faster than earlier. We reduced the time and area of power failure by using automation algorithm on ADS.

IKL Map was drawn by the lines of the equivalent thunderstorm days for 20 years in order to apply to the lightning protection on electric equipments, maintenances and repairs.

Computerized to techniques have been applied to outage call processing system for rapid restoration of power to customers. This paper presents computer aided outage call processing system called '123' system, which has been in operation since 1987. And, also describes its origins, design conception to be considered and its operation effects. From a positive point of view, it shows the functions needs to be added and some problems to be improved. Additionally, it describes the integrated system which has functions of detecting distribution failure, locating failure position by logical computer processing, and although ADS (Automatic Distribution System) has yet to be built up, the primary purpose of the system is to improve service to the customer by means of rapid restoration of electricity outage.

A Digital PABX and a LAN (Local Area Network) will be the major OA systems as the information exchange systems in the telecommunication network of KEPCO. In this paper, The digital PABX and the LAN are generally riviewed and their functions, characteristics and operation results are analyzied.

For the battery energy storage system (BESS), battery is one of most important parts. Various new type batteries for load shifting are under developing. The lead acid battery technology status such as structure, charge and discharge characteristics, life cycle etc. is reviewed and research trend is also introduced.

This paper describes the synthesis method of polyaniline and the characteristics of polyaniline/Zn and polyaniline/Li secondary batteries. Polyaniline was synthesized chemical or electrochemical method and then used as cathod active materials to investigate the characteristics of polyaniline/Zn and polyaniline/Li secondary batteries. Characteristics of polyaniline/Zn battery was affected by additives such as graphite powder and carbon black. Internal resistance, energy density and energy efficiency of polyaniline/Li secondary battery were $167{\Omega}$, 140.7 Wh/kg and 95.6%, respectively.

Single-phase $YBa_2Cu_3O_{j-g}$ (YBC) ceramic samples were annealed at $700^{\circ}C$ under a flowing $O_2$ atmosphere for 0, 18, 36, 54 and 72. hours after sintering. The resistivities(p) and the critical current densities($J_c$) of the samples were measured in a temperature range 77 to 300 K by a four probe method, using silver paint contacts. The variations of the electrical properties with annealing time are explained in terms of flux pinning, percolation probability and randomness, and alignment of grains and twins.The anomalous increases in $J_c$ and $T_c$ observed in sample annealed for a relatively long time possibly due to alignment of grains and twins, may imply the occurrence of superconducting glass state in high-$T_c$ superconducting ceramic.

The effect of isothermal aging on the crystallization of $Fe_{78}B_{13}Si_9$ metallic glass has been investigated by electrical resistivity, X-ray measurements, bending test, thermal analysis and transmission electron microscpy. Amouphous $Fe_{78}B_{13}Si_9$ alloy was annealed isothermally for 5 to 1200 min. between $300^{\circ}C$ and $540^{\circ}C$. It has been found that close relation between relative resistivity and X-ray diffraction pattern showed. The crystalline peaks of ${\alpha}$-(Fe, Si) and $Fe_2B$ are detected by X-ray experiment. The crystalline phases observed by TEH show ${\alpha}$-(Fe, Si) and $Fe_2B$ with dendritic and cylindrical morphology, respectively. It has been also found that the embrittleness of aged samples rapidly increased with the crystallization and was shown before the crystallization.

Using the anisotropic etching characteristics or $N_2H_4-H_2O$ solution, Si diaphragm was fabricated for the integrated sensor. The optimal composition and temperature of the solution in Si etching process was established to be 50mol% $N_2H_4$ in water at $105{\pm}2^{\circ}C$ for both higher etch rate(=$2.6{\mu}m/min$) and better surface quality of etched {100} planes. Under the optimal etching condition, the electrochemical etch stop technique was employed to form Si diaphragm for pressure sensor and diaphragm thickness was exactly controlled to $20{\pm}2{\mu}m$.

This study presents a method of preparing $YBa_2Cu_3O_{7-x}$ ceramic and chlorine doping in it for the purpose of Jc enhancement us ins sol-gel process.Tetramethylammonium-hydroxide and pottasium carbonate solution were added to the aqueous solution of Yttrium nitrate, Barium chloride and Copper nitrate for pH control as well as forming hydroxy-carbonate precipitation. Instead of Barium nitrate, Barium chloride was used for doping chloride impurities in the specimen. The resulted materal showed good high Tc-superconductivity after calcination. Tc and Jc value are 92 K and 120.8 $A/cm^2$ respectively.

Ac, dc and impulse dielectric strengths of $LN_2$ at 0.1MPa were investigated experimentally, referring to the behavior of thermally induced bubble, which might be generated at quenching condition of immerged-cooling superconducting devices. The experimental results show that the bubble shape under electric field stress depends significantly on the applied voltage waveform. With ac voltage, the breakdown voltage of $LN_2$ falls suddenly near to one of the saturated gas at the threshold heater power of boiling onset. In control to this, the reduction of impulse breakdown voltage with heater peter is gradual and the time to breakdown depends on the existence of thermal bubble. These breakdown characteristics can be explained satisfactorily by the bubble behavior under electric fields.

This paper describes the Manufacturing process and electrical properties of ac thick film electroluminescent lamps which made of the mixture of ZnS:Cu,Cl phosphor powder and polymer binding materials. The phosphor layer is sandwiched between two electrodes, one of which is transparent, and is supported by a substrate. The substrate may be glass or flexible plastic or it may be metallic. In this study we manufactured suspend layer which consists of ZnS:Cu,Cl powder suspended in a NBR. As yet our results are behind other commercial product in electrical properties and brightness. However they can be improved by selection of appropriate polymer binding materials, development of blending technology.

The semiconducting bodies were prepared by doping the bariume titanate with $Sb_2O_3,Nb_2O_5$and by subsequent sintering in air. The sintered bodies were annealed between $1100^{\circ}C$ and $1250^{\circ}C$ for 30 minutes to 2 hours in air. The resistivity was measured as a function of temperature from $20^{\circ}C$ to $240^{\circ}C$. The anomalous effect in resistivity occurred all of the $Nb_2O_5$ and $Sb_2O_3$doped barium titanate specimens, which were sintered in air atmosphere, and the most effective PTC effect occurred through 1 hour of sintering time at $1350^{\circ}C$ and 30 minute of annealing time at $1200^{\circ}C$. The resistivity - temperature characteristics seem to be intimately related to oxygen adsorption at grain boundaries and also to the thickness of insulating layers formed at grain boundaries during heat treatment.

Thin films of undoped and Ga-doped zinc oxide have been prepared by rf sputtering. The films deposited on substrates, which have a columnar structure with the c-axis perpendicular to the substrate surface, consist of very small crystal grains (500-1000 ${\AA}$). Considering doping effects, the electrical resistivity of Ga-doped films decreased by an order of $10^3$ compared to undoped films and the optical transmission was above 80% in the visible range and the optical band gap widened as the Ga content increased.

Using pyrosol method, based on the pyrolysis of an aerosol produced by ultrasonic spraying, the deposition of transparent conducting oxides (TCO) such as $In_2O_3$ : Sn, $SnO_2$ : Sb and $SnO_2$ : F on glass substrates was studied. The electrical, optical and structural properties as functions of substrate temperature, dopant concentration, substrate type and carrier gas type were investigated.

In this paper, we studied the diagnostic method of insulation deterioration for 22.9kV CNCV cable using D.C potential decay component. At first, arbitrary D.C high voltage is appeied the CNCV cable for two minutes and switched off in vacuum. And then D.C potential decay components is measured for ten minutes. It is detecting source for cable insulation deterioration that its gradient is. Provisionally, we decided the criterion voltage and select the high voltage meter and S.W.

Lead titanate thin films were deposited on titanium substrates by a chemical vapour deposition(CVD) process involving the application of vapour mixtures of Pb, ethyl titanate( Ti($C_2H_5O_4$)), and oxygen. The lead titanate having a stoichiometric composition has a dc conductivity of $3.2{\times}10^{-12}{\Omega}^{-1}{\cdot}cm^{-1}$ at room temperature. The nonsaturating loops observed in present investigation may be attributed to the $TiO_2$ and TiO layers between the conductive substrate and the $PbTiO_3$ ferroelectric film. The ferroelectric properties of the stoichiometric $PbTiO_3$ film included a remanent polarization of 14.1 ${\mu}C/cm^2$ and a coercive field of 20.16 kV/cm.

Electrically active part of the piezoelectric sound element is a ceramic thin circular disk cemented to a metal base plate (using a type of thermosetting epoxy). The active part is a thin lead zirconate titanate disk (PZT). The piezoelectric sound element is so dimensioned that its basic resonance frequency is approximately if the center of the audible frequency band: This frequency is mainly determined by the geometry and the sort of the metal base plate materials. In this study, four kinds of PZT ceramic and two classes of thin metal base plate were prepared. It is observed that dielectric and pizoelectric properties relate to acoustical properties (particularly sound pressure level).

The Charcteristics of the HCD ion plating system for TiN coating was Investigated. 1-V curvet of the HCD ( hollow cathode discharge ), radiation temperatures of the Ta tube and the Ti pool and the electron density and the temperature of the generated plasma are shown. The preferred orientation and the micro-hardness of coatings performed by HCD process are studied.

A Modified equivalent circuit by combining a series and parallel of polymer matrix for estimating the dielectric constant ${\bar{K}}_{33}$ values changing the volume percent of $PbTiO_3$, the dependences of frequency for the 713 and dissipation factor for 0 - 3 composites was derived. The difference of the dielectric constant and dissipation factor between the calculated and measured values became smaller at higher volume percent of $PbTiO_3$. There was, good agreement between the calculated and observed results for 70 volume percent of $PbTiO_3$ and 30 volume percent of Eccogel composite at 1(KHz), 25($^{\circ}C$). The optimized variable x was 0.94 in $PbTiO_3$ ceramics. $PbTiO_3$ powder and Eccogel polymer were used as piezoelectric fillers and matrix, respectively.

미세거리 조정용 극소형 기기인 마이크로 웜을 소개하고 그 원리및 설계에 필요한 사항의 이론 분석한 것을 설명하였다. 또한 이의 응용으로서 유량을 제어 할 수있는 밸브, 압전형 모터 등에 관해 소개한다.

Poling piezoelectric ceramic-polymer composites with 0-3connectivity is difficult because of the high dielectric constant of most of the ferroelectric filler materials, and the high resistivity of the polymer matrix. To aid in poling this type of composite, conductivity of the polymer phase can be controlled by adding small amount of a semiconductor phase such as germanium, carbon or silicon. In this study, flexible piezoelectric composites of $PbTiO_3$ powder and Eccogel polymer were developed using small amounts of a semiconducting phase. These composites were poled rapidly at low voltages, resulting in properties superior to composites prepared without a conductive phase. The effect of addition of various conductive phase with different volume percentage on the dielectric and piezoelectric properties of the composite are discussed here.

Composite insulating materials have the defect of interface. To minimize the defect of interface of GFRP (glass cloth reinforced plastics), coupling agent is treated. In this paper, the method of coupling agent treatment has been studied. The result shows that the optimum electric and mechanical properties is obtained for the sample treated on the glass fiber with 0.3% amino silane water solution.

Linear and nonlinear complex permittivities have been measured for an alternating copolymer of vinylidene cyanide(VSCN) with vinyl propionale(VPr). It is found that the third order permittivity ${\varepsilon}_3$ depends upon frequency according to a function V ${\varepsilon}_3$/ ${1+(j{\omega}{\tau}_3)^{\beta}}^3$ while the linear permittivity ${\varepsilon}_1$obeys a Debye type function ${\nabla}{\varepsilon}_1$/ {1+$(j{\omega}{\tau}_1)^{\beta}$}. Experimental results are well fitled by predicted functions except at low frequency where dc conduction dominates. The relaxation times ${\tau}_1$ and ${\tau}_3$ at same teperature are nealy equal and depend upon temperature according to WLF form. The relaxation strengths ${\nabla}{\varepsilon}_1$ and ${\nabla}{\varepsilon}_3$ have a peak at the vicinity of glass transition temperature (Tg). The strength ${\nabla}{\varepsilon}_1$ has a value of -9 order and ${\nabla}{\varepsilon}_3$ has a negative value of -25 order. The analysis of mechanism by combined knowledge about linear and nonlinear permittivities and dipole moment gives us an imformation of the electrical and thermal dipolar motions in this copolymer.

Recently, it is reported that the behavior of thermal $SiO_2$ under high electric field and current condition has a major effect on MOS device degration. Furthermore, when thin oxide films are applied in practical device, the presence of oxide defects will be a serious problem. In this paper, because TDDB is the useful method to measure the effective density of defects, we stressed MOS structure that is 150 A of thermally grown $SiO_2$as a function of electric field (9-19 MV/cm), temperature ($22^{\circ}C$ - $150^{\circ}C$) and current. By examing TDDB under positive voltage, long-term oxide breakdown reliabiliy is described. From these data, breakdown wearout limitation for the oxide films can be characterized.

In this paper, the electrical conduction phenomena of oriented polypropylene film were studied. Especially, as for the range of negative characteristics, it is observed that as increasing ambient temperature, the characteristics are shifted gradually towards the low intensity side of applied field with the decreasing width of the range as well as the fact that the currant oscillation takes place at the both transition points of the characteristics and that the point at the place the dielectric breakdown, occurs. Finally, it is also suggestive that the oscillation characteristics observed on the negative resistance range of the biaxially oriented specimen show the possibility to utilize it as active element materials.

An infrasonic wide band transducer fabricated by polyvinylidenefluoride[PVDF] is studied experimentally. The sensitivity of transducer is fixed -53[dB] at frequency range from $10^{-2}$[Hz] to 2[Hz] and fixed -42[dB] range from 10[Hz] to 400[Hz] respectively. The resonance frequency of the element is 14[Hz], which is accord with the mechanical resonance frequency 25.5 [Hz]. We conjecture that the element is applicable to acoustics, communication system,seismological observation and other similiar fields.

It has been reported that the formation of conductive carbon path is mainly affected by scintillation. In this paper, mechanisms of tracking deterioration are reviewed by counting light pulse with IR photodiode. The influence of applied voltage and molecular composition of materials in the tracking breakdown is also reviewed by the Number of Pulse curve.

Ultra Tihn Film of 100 angstrom-order is fabricated by Langmuir-Blodgett technique. The conductivity of this this measured by the direction of either vertical or horizontal axis is results in a quite different value. Specific inductive capacity and effect of time variation of LB films are also considered.

Very thin gate oxide(100-300A) MOS capacitor has been fabricated. The effect of series resistance must be calculated and the exact metal-semiconductor work function difference should be obtained to get the fixed oxide charge density exisiting in oxide. Dilute oxidation make sagy to control oxide thickness and reduce fixed oxide charge density. In case of dilute oxidation, fixed oxide charge density depends on oxidation time. If oxide is very thin, the annealing effect is ignored.

Dielectric breakdown strength (Eb) of thin Poly(Vinylidene Fluoride ; PVDF) film is studied in the temperature range between 4.2 K and 400 K. The results of this study can be summerized as follows. 1) Temperature dependence of dielectric breakdown strength (Eb) can be devided into high and low temperature regions. The critical temperature (Tc) at which two regions are devided depends on applied voltage. 2) Dielectric breakdown strength (Eb) by pulse voltage is higher than that by DC voltage. Especially this difference is remarkable at low temperature.

Nitrided oxides have been recently investigated for the application as a replacement of thermally grown $SiO_2$in the MIS devices. In this paper, thin oxides were nitrided in the $N_2$plasma ambient. After B - T stress is performed on the sample, it was noticed that the current density is increased. From the I - V measurement, dominant conduction mechanism of oxynitride films appeared to be Fowler - Nordheim emission. And also its breakdown strength is increased about 2.2 MV/cm compared with the oxide films.

Phosphorus nitride films on InP surface were grown by a Photo-CVD (chemical vapor deposition) technique over 100-250 $^{\circ}C$ range of substrate temperature, which is based on direct photolysis of $PCl_3/H_2$ and $NH_3$ gas mixtures by 185nm ultraviolet light from a low pressure mercury lamp. The film growth rate ed the refractive index(n) were shown about 700-800 ${\AA}/hr$ and 1.7-1.8, respectively. Composition ratio and interface properties were analyzed by AES(Auger Electron Spectroscopy) and XPS (X-ray Photoelectron Spectorscopy) technique.

Diamond is synthesized from the gaseous mixture of carbon monoxide and hydrogen by microwave PECVD. $10{\times}10mm^2$ silicon wafers are used as the substrate,and it can be raised more than $900^{\circ}C$ by microwave absorption, radiation by plasma and bombardment of ions. The changes of the morphology and the growth rates of the deposits with the experimental conditions are examined by Scanning Electron Microscopy. The d values of all the deposited films concide with those of powder diffraction data in XRD. In Raman spectra, the peak of the deposit coincides with that of the natural diamond which has a value of 1332.5 $cm^{-1}$, and the broad peak from 1360 $cm^{-1}$to 1600 $cm^{-1}$which represents the amorphous graphite was observed in the higher concentration of carbon monoxide.

The interrupting capability of circuit breaker to have an effect on stability and reliability of the power system is largely determined by the fault current and prospective TRV (prospective transient recovery voltage). The prospective TRV, which is essentially a system function determined by the elements of the connected circuit, is not constant for a given system location but is affected by a number of variables. Therefore, the purpose of this study is to analyze the prospective TRV of KEPCO's 345KV transmission system by using EMTP (Electro-Magnetic Transients Program) and to compare the calculated values with the standard values in KSB 150 (1976)

Some magnetic probes for theta-pinch experiment have been constructed. Methods of building the coil, conecting it to the oscilloscope, shielding and enclosing the probe are discribed. Such a probe has been used to measure the magnetic flux penetrating it within theta - pinched plasmas.

A 1800KV testing chamber for gas insulation has been developed. To develop the chamber, all parts consisting of the chamber, namely, bushing, main chamber, shield, conductor bus, inspection window, feedthrough, and spacer have been designed based on numerical electric field analysis. This paper presents the detailed design philosophy and methods of the chamber.

Discharge characteristics of a commercial made Xe-flashlamp have been studied for the pumping source of dye Lasers. The rise-time, FWHM, intensity and energy of pumping light pulses of the lamp were measured as functions of the serial resistor and applied voltage. The grid effects of the lamp on pre-discharge and the spectrum of light pulses also have been investigated.

It is well known that switching overvoltages in the electric power system can damage electric power apparatus. To investigate switching overvoltages, electric power system has been modeled using mathematical equal ions. Using developed model, switching overvoltages in the transformer terminal have been computed and analysed.

In this paper we introduce electrical and mechanical properties of PPLP, an insulation system of Cellulose/Extruded Polypropylene/Cellulose Paper, and characteristics of 345KV O.F cable employing the PPLP. This cable shows dielectric loss less than 50% and has excellent impulse breakdown strength higher than 17%, respectively, compared with those of the conventional cables. Accordingly, a more compact cable with reduced thickness of the insulation layer, which has remarkable profits in economics, has been developed.

A program for numerical analysis of induced lightning surge is developed. The program first converts simultaneous differential equations into simultaneous difference equations for line sections without transition points, and calculates the line voltage and current by solving a determinant. It, then, calculates the line voltage and current at transition points by applying kirhhoffs law. This program is potentially useful in a wide range of applications for investigating the effect on distribution lines of lightning protection equipment such as lightning arresters and overhead ground wires.

This paper presents the algorithm of a new optimization method for axially symmetric electrode and insulator. The initial surface contour is divided into circular arc elements. The radii of the elements are determined so that the surface field distribution becomes uniform keeping the minimum gap distance and the direction of correction. By means of two examples, one for an electrode and the other for a spacer, the convergence behaviour and several restrictions of optimization are discussed.

As a first phase of plasma study intended for semiconductor processing research, we have studied the discharge phenomena. In particular, we have obtained a specific formula for the breakdown voltage as a function of the neutral state pressure of reactive gases. Our experimental results with H2,O2,Ar,CF4 seem ro verify this formula. In addition we find the voltage levels for various gases in the descending order of CF4>O2=Ar>H2 in high pressure region, while H2>CF4>O2>Ar in low pressure region. When H2 and CF4 were mixed, we observe the overall voltage dominated by the gas with lower breakdown volotage.

In this paper, we study about the degree measurement which is applied by the pirani gauge's theory arid the basic analysis of plasmsa which is generated by the D.C glow discharge.

This paper presents an algorithm for electric field analysis which is essential to insulation design of extra-high voltage oil-filled cable accessories using finite element method. Governing equation is induced by electromagnetic equation. Variational method is adopted for FEN formulation. Automatic mesh generation which saves time and labor is introduced for the input data. The application results of proposed algorithms were used for insulation design to develop 345kV cable joint.

Low inductance 4-channel spark gap switch was designed and performed. At NTP, self-breakdown voltage is 29kv, 43kv and 33kv when ratio of seperation($d_1$: $d_2$) is 1:1, 1:2 and 1:3 respectively.

$CO_2$ lasers are used in the various industrial fields since the development of $CO_2$ laser in 1964 It is because $CO_2$ laser is more efficient, more powerful than other lasers and $CO_2$ laser light of wavelength $10.6{\mu}m$ interacts with materials well. Thus $CO_2$ laser is used for industrial application such as cutting, punching, welding, surface treatment of metal and nonmetalic materials, isotope separation, etc. Already other research institutes including some universities have recognized the advantages and importance of the $CO_2$ laser, and studied it. However, its technology is in elementary state yet Therefore,we started this study to develop present $CO_2$ laser technology more highly and to fit it. The main purposes of this study are to acquire various technologies such as high voltage, high pressure glow discharge, vaccum and optical cavity design.

154kV insulator strings are frequently damaged by lightning strokes, overvoltage and contamination. And this insulator damage inflicts a loss on the power company. The purpose of this paper is to develop the arcing horn as a protective device of 154kV insulator strings against lightning flashover and overvoltages. So We have developed the arcing horn which is suitable for 154kV transmission line and estimated the performance of arcing horn by high current arcs and high voltage tests.

Single particle orbit in plasma is obtained by drift Hamiltonian formulation in magnetic coordinate. The collisional effect is implied by Monte Carlo Method and the velocity space diffusion, energy transfer to the back ground plasma and the variation of energy distribution of test particles are investigated from many particles analysis.

A DC thermal plasma generation system for both LPPS and APPS was designed and its characteristics was analysed. Discharge experiments for 60 conical and cylindrical type anode nozzle were conducted and the results were compaerd each other. The flow dependence and the electrode gap dependence were precisely explained and especially voltage jump phenomena under the existance of the parallel magnetic field was studid.

In this paper, an improvement of the EBP(error back propagation) learning speed using an acceleration algorithm is described. Using an acceleration algorithm known as the Partan method in the gradient search algorithm, learning speed is 25% faster than the original EBP algorithm in the simulaion results.

This paper deals with the computer generation of Korean characters by the structural coding which results in higher flexibility and compactness. Our method by which Korean characters are designed is characterized as follows : The list of primitives for Korean text is extracted by structural coding rule, and the knowledge-base is used for handling various primitives.

Many Korean graphic cards have been produced. But, due to the diversity of korean code system all korean graphic cards produced have been adapted in specific code system. Therfore, considering in KSC-5601-1987, the paper propose a Korean decoder independent of code system

In this paper a Korean authoring system is designed to write a CAI courseware in Hangul/English by an author who is a nonprogrammer. It saves nock time in authoring a courseware and maintains high level transplantity among CAI systems. By interfacing ah expert graphic utility, image information can be processed more easily and efficiently. Programming control of the flow of CAI courseware can be ramification and individual learning possible, fitting various demands of learners and learning and learning ability.

This paper proposes the recognition of Korean character by using the given pre-segmented area. For higher processing speed, we introduce the techniques for pruning the unused segments. And, new thinning algorithm is used for finding skeleton of each segment.

In this paper, we introduce the three-dimensional Korean character display by using 2D fonts and character depth. Character segments are designed by the set of vertex at run time. Character depth is applied for 3D visualization. And, the variation of eye-point and distance of object is used for 3D character animation.

The object of this parer is on the design of an broad board classifier for connected. Korean digit. Many approaches have been applied in speech recognition systems: parametric vector quantization, dynamic programming and hiden Markov model. In the 80's the neural network method, which is expected to solve complex speech recognition problems, came bach. We have chosen the rule based system for our model. The phoneme-groups that we wish to classify are vowel_like, plosive_like fricative_like, and stop_like.The data used are 1380 connected digits spoken by three untrained male speakers. We have seen 91.5% classification rate.

In this paper, a program controlling an auto-audio media - cassette deck - by a 16 bit personal computer is studied in order to execute audio and visual learning in CAI. The results of this study are as follows. 1. Audio and visual learning is executed efficiently in CAI. 2. Access rate of voice information to text/image information is about 98% and 60% in "play" and "fast forward" respectively. 3. In "fast forward", quality of a cassette tape affects voice information access rate in propotion to motor driving speed. 4. Synchronizing signal may be mistaken by defects of tape itself.

We have developed a simple and efficient hangul recognizing automata as a part of a graphic project. this automata accepts both English and Korean code from a Korean syllable from a stream of Korean alphabets. The automata then mates a 2 byte Hangul combination code from the recognized syllable and passes that code to the graphic system.

Concept is the set of selected neurons in a stable state of a neurel network. The Recognitron uses a parallel feedback structure to support concept learning. A number of clusters can exist in response to a given input, each of which make up a selective neuron. There are supervised and unsupervised learnig methods in concept teaming. In this paper, we have chosen unsupervised learning. Also, a new concept called relaxational learning has been introduced to stop runaway weights

Our work is an attempt to recognize objects without a rigid ordering of steps and with fuller use of previous results as analysis proceeds. We assume that the difference in brightness between the objects and the background is large enough to detect the background boundaries easily. Lines are mostly proposed insted of found by exhaustive search in the scne, the program is relatively efficient.

In multiple current source inverter, generally, transformer connection method and direct connection method in output side have been used. But these methods have faults such as the increment of the number of inverter and the need of the transformer for changing phase in order to get above 12 phase. In this system, we obtained the output currents of 24 phase by adding 2taps in 12 phase inverter. Therefore, this system has such characteristics as the miniaturization of devices and the simplicity of control signal by controlling two inverters and two SCRs for changing taps.

This paper presents a new converter composed of a P.W.M controller and a resonant converter which operates at a constant frequency. This converter has relatively simple control circuits and high conversion efficiency. The optimum operating point corresponding to maximum efficient for the S.R.C and P.R.C operating above resonance is obtained.

This PWM inverter are used bridge circuit of two pair complementary transistor at each phase. The operation signals are 3 level PWM wave of W type and M type modulation, Which were obtained from switching time data by switching position calculation of triangular and sine wave. The output voltage waveforms of this inverter have the 5 level phase voltage and the 9 level line voltage of PWM.

Recently, PWM cycloconverters that are frequency conversion system have been studied for eliminating do links of conventional converter and inverter systems. A new real-time method for generating PWM patterns is proposed in this paper. This method realizes sinusoidal input and output currents, controllable input displacement factor regardless of load power factor, and maximum output voltage range. Finally, feasibility of the proposed method is confirmed by simulation and experiments.

Recently developments of high-speed Semi-conductor Switches as Power MOSFETS, Power IGBT, power SIT have enwidened the performance of classical inverter configuration, and also allowed the practical applications of new inverter configuration, with improved performance and wider operating zones. Static power converters are now used in a great variety of applications including induction heating, high-frequency generation, DC/DC power converter, etc.

In order to reduce harmonic contents in the inverter output, various PWM ( pulse with modulation ) techniques have been utilized. This paper suggests a single phase inverter with 4-level output and its PWM control scheme. The proposed 4-level output inverter shows better performence than the 3-level output one in respects of the current error and the switching frequency.

In this paper, the way that input voltage and input line current as a control variable is provided as one unit is projected. Till no, have denied with three phase balanced load. But, in that case, total power factor compensation is difficult, for to control each phase at unbalanced load. Therefor, in this paper suggest of the scheme that three phase unbalanced load is controlled by each phase and input total power factor is compensated unit input factor. therefore, in this paper suggest that three phase unbalanced load is controlled and the method in compensation of unit input factor to be attended by unbalanced load. Besides, the object of control is calculating quantity for input voltage and input line current for the point at issuse make to improve of control method at unbalanced load. As a result, control system of each phase could maintain as a unit input total power factor has been state diviation error of 2% with unbalanced load.

A high-frequency asymmetrical PWM control technique is proposed which can improve the input power factor of ac chopper and also suppress its harmonic contents of currents at both its input and load sides and the acoustic noises by its switching semiconductor devices. The ideal switching function for the proposed technique is derived and hence converted into asymmetrical PWM pattern for practical implementation of ac voltage regulator. Also the various power circuits of three phase AC choppers are suggested. The theoretical characteristics of the proposed PWM technique are investigated by digital simulation.

The introduction of resonant link inverters has allowed the use of much higher switching frequencies in induction motor current regulators. The resonant link inverter,however, requries the use of discrete time switching strategies. This type of controller,while giving the best possible performance, is difficult to implement, since motor parameters must be calculated or measured. The delta modulated current regurator (DMCR) has been introduced as a controller without additional state feedback. A discrete pulse modulated current regulator which controls load current is introduced in the paper.

Two dimensional numerical analysis program of power VDMOSFET structure has been developed. Modeling and analysis on the electrical characteristics of the device are presented These are available for the device structure optimization and physical understanding of the behavior of the device

The line equations can be expressed by a set of nonhomogeneous differential equation where forcing terms of these equations have been adopted. Equivalent-circuit representations of this paper are derived from solutions of the equations. The contribution of the external wave to the line is expressed in terms of ideal sources in the form of a cascade connection to the line. These representations art conveniently applicable to the various types of transmission lines because these Lines can often be written in the form of a chain matrix.

For the purpose of increasing supply reliabiity in power line, high reliable voltage and current sensors must be needed. This paper describes the principle and result of the only optical voltage sensor based on BSO pockels cell.

Drive malfunction take many forms and every possible one must be protected against. Until recently a separate analog device was needed for each type of malfunction. In this approach to simplified, more reliable motor-circuit protection and control, a microprocessor's digital controller for motor control center simultaneously examine most of the possible sources of circuit trouble and has more efficent functions (sequence control,display) than the conventional motor control center. The result of standard surge tests provided a realistic evaluation of the surge withstand capability of equipment.

A constant V/F control system of voltage contrlled PWM inverter has a unstable operation of the low- speed and the light-load. In this paper, the authors propose stability control with idealized operation of induction motor by the neglect of primary leakage inductance and resistance. Also ldealized operation system is adopted voltage error, feed back impedance circuit, and increasing resistance from dead time of switching is compensated by the soft ware with u-processors. The proposed simulation of the idealized control method is proved at the low-speed operation for three phase induction motor.

A position control system of D.C. Servo motor based on discrete variable structure system with sliding mode is presented. The sliding mode has been designed for a continuous system, but it is often realized in digital fashion because the complex switching logic can be easily carried out. In digital control system, the ideal sliding mode does not occur since the structure can't be switched during sampling interval. However, there can be exist a motion which is confined to a regoin including the sliding surface and proceeds to the origin along the surface. This notion is called quasisliding mode. In this paper, we introduce this control scheme to the D.C. Servo motor position control in order to reduce the chattering phenonenon.

This paper describes a new pwm scheme of variable speed control for induction motor. The proposed scheme have the programmed pwm switching pattern which have the doninant harmonic elimination over the wide range of output speed in induction motor. Experimental results of proposed scheme hare high quality output current, voltage and torque than that of conventional pwm scheme. Therefore proposed scheme have the smooth operation and suitable for variable speed control in induction motor.

The air-cooled waterwheel generator has a fan connected to waterwheel shaft or motor driven fan or fans. The fans are operated at constant speed, constant input, regardless of generator loss which is varied according to generator output and coolant the perature. Energy savings may he possible if the cooling air flow is controlled according to generato output and air temperature depending on season. The simulation and experience have been done on the 22.6 KVA Waterwheel generator by using AC variable speed drive. The results gave us los cut of generator.

All Inverter fed induction motor systems which the switching patterns are determined by the approximated sinusoidal modulation techniques have many troublesome problems such as the current ripple duing to harmoic components. Therefore, in this paper, the current and torque pulsations for a inverter fed induction motor drive system are analyzed and specified theoretically and the determination techniques of optimal switching patterns for minimization of these factors are presented. Also, these simulation results are compared to the ones obtained from the realized experimental system by one-chip microcomputer, 8751.

Bilateral Variable-Ratio chopper system performs Step-down chopper and Step-up chopper operations automatically every operating period of the chopper. The Ratio between Step-down chopper and Step-up chopper operations is determined by a Tine- ratio and the circuit elements. In this paper, we suggest that this chopper system can operate variable speed control of the electric motorcar when it is applied to the electric motorcar.

The application of Variable Structure System (VSS) to the position control of a Permanent Magnet Synchronus Motor is discussed. VSS is expected to be a powerful and potential tool to construct new control strategy for ac machines, since the resulting system shows robust performance to parametic variations and disturbances. An adaptive VSS which can make corrections or adjustments in the parameters of the control device of the VSS in accordance with the current values of the plant parameters and the constraints on the control is preposed. Various simulation results are reported to show the validity of the proposed control method.

Vector control has been widely used in AC machines for precise control. The application of Vector control for the permanent magnet synchronous motor drive and complete modeling,simulation and analysis of the drive are discussed in this paper. The nonlinear model of the permanent magnet synchronous motor is linearized. Then the theory of vector control is applied to the linearized model in designing controllers. The operation and relevant mathematics model of s pseudo derivative feedback controller are then presented. Two different speed controller design are then considered. A comparative evalation of the two speed controller is also presented.

In this paper, maximum torque per current ratio of the interior permanent magnet synchronous machines including compensation of Ne-Fe-B magnets in negative temperature sensitivity is described. This compensation can be achieved by measuring of motor temperature only.

In this paper, the commutating devices of the forced commutating circuit and the relation between load current and source voltage are theoretically analyzed, by this approach commutating condition is considered. As a result some basic design methodes of commutating circuit are presented, whitch commutating loss becomes low and commutating failure is not occured.

The full-bridge series resonant converter is analyzed to limit the maximum values of the current and the voltage across resonant capacitor in the case of load short. If the converter is operated in the optimal region derived in this paper, the maximum value of short-circuit current will be smaller or equal to that of the current in steady operation. Since the additional facilities for the protection against load short do not need, converters have advantages in weight, size, and cost.

This paper describes on the current control characteristics of the voltage type converter. The DC output current of the converter can be controlled by a phase control without feedback loops. The characteristics may be applied effectively to the motor drives.

This paper describes newly developed high performance control system for vector controlled induction motor. In order to realize this system, the authors are adopted the current controlled PWM inverter with hysteresis controller. A priori knowledge of the motor parameters is need in order to implement indirect vector control on induction motor drive systems where the position of rotor flux is estimated. This paper presents some of the relevant mathematics necessary to study parameter sensitivity in induction motor servo system. Simulation results demonstrate the predicted performance.

광섬유와 micro변형기를 이용하여 다점 압력 계측 system을 구성하여 실험을 행하였다. 그 결과 pulse generator와 analog switch를 이용함으로써 100ns의 광 pulse를 쉽게 얻을 수 있었으며, 또한 3개의 광 pulse를 analog switch를 이용하여 쉽게 분리할 수 있었다. 한편 변형기에 가한 힘과 광 손실간의 상관관계를 이론치와 비교하여 조사한 결과 힘과 광손실간의 상관관계는 이론치와 실험치가 유사한 경향을 나타내는 것을 알 수 있었다.

The scattered light intensity from a spherical particle passing through the cross-over region of two coherent laser beams, varies periodically. Photodetection of this light beams produces a periodic signal of varying amplitude. The phase of the signal varies with the particle size and refractive index, the beam crossing angle and wavelength, and the position and size of the scattered ligth collecting aperture. In this paper the phase variation with respect to the particle absorptive index of retraction, collecting lens size and beam crossing angle is calculated using both Mie scattering theory and reflection theory. The two theories show good agreement in phase predictions, especially for large absorptive indices and for small collection lenses. Both theories predict phase to be inversely proportional to the beam crossing angle.

The simulation results of the third harmonic conversion with 1.064 um Nd :YAG laser using polarization mismatch method are reported. The third harmonic conversion efficiency was over 65% for the Gaussian incident pulse of $300{\sim}400MW/cm^2$ peak intensity, and over 80% for $3{\sim}4GW/cm^2$ peak intensity pulse. The dependence of the third harmonic conversion efficiency' on the variation of incident polarization angle ${\theta}_p$ and angular discrepancy ${\Delta}{\theta}$ of phase matched angle ${\theta}_m$ is discussed.

We have developed 3-stage of Magnetic Switch System based on the nonlinearities of ferromagnetic material used in the saturable inductor, and made experiment of parameter optimization and output stabilization of Magnetic Switch System. The cross-section and conductor burns of each satarable inductor were optimized 30 $cm^2$ 19.25 $cm^2$ 5, and 25 $cm^2$ 2, respectively. With this condition, 6.2 us [FWHM], 96 A pulse at first stage was compressed into 0.4 us[FWHM], 1.61 kA pulse at last stage. The current gain and compression ratio were 16.8, 17, respectively. ln addition, System output was stabilized with reset current of 6 A, 200 us.

We have developed analysis program of discharge chracteristics of KrF laser system with charge transfer type, that studied about deposited energy, nonlinear discharge, and electron number density in the laser tube. With this program, voltagr, current, and deposited energy was calculated 27 KV,32.6 KA,200 MW at total pressure 2 atm and charging voltage 33 KV, respectively. At this condition, circuit parameters are L1=150nH, R1=$0.3{\Omega}$, L2=15nH, R2= $0.3{\Omega}$. In addition, nonlinear discharge resistance and electron number density was calculated ${\infty}{\sim}0.17{\Omega}.1{\times}10^{16}cm^{-3}$, respectively.

The driving-point impedance of the center-fed planar dipole antenna is obtained using the method of moments (MOM). For the thin dipole antenna, our numerical result is compared with that of the inverse method by D. R. Rhodes as well as the known solutions of equivalent wire antenna. For the frequencies of L-band and S-band, the driving-point impedances of the thick planar dipole antennas are measured by experiment and compared with the numerical results.

A rate equation model describing the ultrashort pulse formation is presented. The temporal and energy behavior of the distributed feedback dye laser predicted by the model has been compared the earlier papers on DFDL's. The observed good agreement allows application of the theoretical model for picosecond laser.

The characteristics of proton-diffused $LiNbO_3$ optical waveguides with self-aligned $SiO_2$-cladding are reported. When the proton diffusion occurs, the $SiO_2$-cladding limits the lateral diffusion of protons by out-diffusion of protons in unclad region. Proton indiffusion in depth direction is promoted by inhibition of out-diffusion in clad region. Consequently, the mode profile in depth direction can be nealy symmetric. The extent of the proton exchange was observed by measuring the infrared absorption peak at about $3500cm^{-1}$. It is confirmed that proton diffusion with $SiO_2$-cladding has structural excellency.

$CO_2$ laser beam was focused a ZnSe lens onto the center of the occlusal surface of extracted lower molars. K-type thermocouple was contacted with the pulp chamber and the changes of temperature in the pulp chamber during and after the laser irradiation were measured as function of the power of laser beam, the time of laser irradiation and thickness of the sample. An empirical formula for temperature effect was derived from the measured data.

Pure mono Silane(Purity: 99.99%) was used as a thin film source and [$SiH_4$ + $H_2$ (5%)] + [$PH_3$ + $H_2$(0.05%)] mixed dilute gas was used for p-n junction diode. The substrate was P-type silicon wafer (p=$3{\Omega}$ cm) with the direction (100). The crystalline qualities of deposited thin film were investigated by the X-ray diffraction, RHEED and TED patterns and the voltampere characteristics of p-n junction diode was identified by I-V curve.

The CO laser is one of powerful light source for laser magnetic resonance spectroscopy in the mid-infrared region of the spectrum because of its wideband operational characteristics. In this work, a liquid nitrogen cooled cw CO laser is developed to allow broad-band operation from 5 to 8 ${\mu}m$. The design details will be presented.

This paper proposes two types of the preview algorithms to predict the joint velocities and joint positions, and deals with a control approach using the preview algorithms for the precise trajectory control. Specifically, a predictor an the form of discrete time state equations is proposed based on the robot dynamics model linearized by the computed torque method. And another state predictor is proposed by the beat line fitting in the least square sense, where present joint velocities and positions and several past positions are employed. Then computer simulations are performed for the SCARA robot with two d.o.f. to show the validities of the proposed algothrithms.

In this paper, we describe the PTP notion of robot manipulators by neural networks. The PTP motion requires the inverse kinematic redline and the joint trajectory generation algorithm. We use the multi-layered Perceptron neural networks and the Error Back Propagation(EBP) learning rule for inverse kinematic problems. Varying the number of hidden layers and the neurons of each hidden layer, we investigate the performance of the neural networks. Increasing the number of learning sweeps, we also discuss the performance of the neural networks. We propose a method for solving the inverse kinematic problems by adding the error compensation neural networks(ECNN). And, we implement the neural networks proposed by Grossberg et al. for automatic trajectory generation and discuss the problems in detail. Applying the neural networks to the current trajectory generation problems, we can refute the computation time for trajectory generation.

This paper presents two methods for reducing the position error of the robot hand. The first method change the parameters of the D-H transformation using real position error. The other one calibrates the joint angle by using the datas from the known teaching points. SCARA type robot is used for verifing the validity of the proposed methods.

In this paper, the navigation problem for a mobile robot is investigated. Specifically, it is proposed that simple guide-marks be introduced and the navigation scheme be generated in conjunction with the guide-marks sensed through camera vision. For autonomous navigation, it was shown that a triple guide-mark system is more effective than a single guide-mark in estimating the position of rho vehicle itself. the navigation system is tested via a mobile robot 'Hero' equipped with a single camera vision.

In this paper, force control for a multi-legged walking robot is investigated. For stable but relatively rapid walking, a simple force control algorithm is proposed in conjunction with the position control system. The proposed control method is tested on an experimental one leg system of two degree of freedom with a force controller using a position controller and a monoboard microcomputer to implement the proposed control algorithm. The experimental results shows that the control algorithm can be applied for walking in a terrain with wide range variation.

This study has been aimed to analize and evaluate the performance of the coding algorithms for the handwritten signals such as the telewriting systems. Zone Coding and Differential Chain Coding algorithms have been analized and evaluated on the basis of time and space complexities. According to the simulation results, Zone Coding algorithm has shown better decoding performance from the viewpoint of the Root Mean Square decoding errors, but Differential Chain Coding algorithm has shown better data compression ratio and flexibility of its usage, along with its moderate decoding RMS errors.

This system exchange half-duplex serial data at 1200 baud by FSK modulating a carrier frequency at 200KHz over the 110V A.C. power line. Transmitter output voltage to A.C. line is 4V p-p and line sensitivity is selected 2.54mV because CISPR Noise limitation is $66dB{\mu}V$ at 150 ${\sim}$ 500KHz. The designed and realized system has abtained system margin of 58 dB and probability of error, Pe = $1.78{\times}10^{-7}$ was obtained

A communication system through distribution lines was developed for distribution automation. Since all facilities in distrbution systems are connected by distribution lines, economical communication systems can be realized by using these lines as data transmission lines. But it has a problem in transmission reliability bcause of its sensitivity to noise and impeadance. Therefore, to cope with this problem. measurement and analysis of the communication characteristics are made according to the influence of load impeadence change, signal level and noise generated in load. Field tests were carried out at Kyung Ki branch of the KEPCO for half year starting in Feburary 1988.