1994.11a
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It is shown that the power flow considering the voltage characteristic of the composite load has some difference comparing with conventional load flow in this paper. When the load flow is used in a study of the static voltage stability, it is necessary to consider the voltage characteristic of load, since the composite load of a typical power system bas constant power, constant current, and constant impedance characteristic. The load is modeled to a polynomial form in here, and used in solving the load flow problem. In this way, the effect which the voltage characteristic of the load has on several voltage collapse proximity indicator based on sensitivities is compared with the conventional load flow, or with another load model having a different voltage characteristic. In this paper, the voltage collapse proximity indicator using the sensitivity of real power for transmission loss is also proposed, and compared with other indicators.
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In this paper an attempt is made to understand the voltage stability when the power system networks are represented by the differential-algebraic equations (DAEs) form. The problem is analyzed by interpreting the shape of constraint manifold, based on the singular perturbation model. The global picture or constraint manifold is given to show how the local shape or constraint manifold can be used to guess for the system behavior. The gradient analysis is used systematically to obtain a local shape or the constraint manifold.
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FACTS concept is the control of power flow and increase of the loading on existing lines to the thermal limuts. This paper focuses on the ability of the thyristor controlled series compensator (TCSC) to stabilize the disturbed power systems. The result shows the potential benefit of the TCSC in addition to the role of controlling the steady state power flow. In order to show the effectiveness of controlled series capacitor, power system dynamic model is augmented and the effect of the SC into the power system dynamics is included. As a control algorithm, Linear Optimal Control theory is applied.
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Traditionally one convex cost function for each generation is assumed in economic power dispatch. However, it is more realistic to represent the cost function as a piecewise quadratic function rather than one convex function. This paper presents evolutionary algorithm approaches to solve the problems of economic power dispatch with quadratic cost functions and piecewise quadratic cost functions. To improve GA, EP and ES characteristics. optimization methods combining GA with ES and EP with ES are proposed. The results for the proposed algorithms are compared with those of numerical method and show the better solutions in the ELD problem.
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The economic operation in power systems has long been in keen interests for power system engineers. The classical equal incremental fuel cost rule is still the basis for it, even though more elaborate tools such as optimal power flow have been developed already. The classical method requires usually many iterations, while the optimal power flow shows often some difficulties. This paper suggests a single step solution based on the classical method revisited. The concept is shown graphically. Three sample systems are compared. The proposed approach has shown a single step solution regardless system sizes, while the conventional methods require many iterations.
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The cogeneration system has a advantage of producing electrical and thermal energy simultaneously. therefore, this system is encouragable to the business proprietor and the nation like us which has the problem of limited energy. Presently, there is a few cogeneration system for new city and industrial complex. But the building cogeneration system is dull in application because of legal limitation and poor tax support. In this paper, we simulate economic propriety of the building system under the support which is applied to industrial system. And we simulate the effect of each support item on the economic propriety in aspect of payback period.
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The degree of forecast accuracy with BP-algorithm largely depends upon the neuron number in hidden layer. In order to construct the optimal structure, first, we prescribe the error bounds of learning procedure, and then, we provid the method of incrementing the number of hidden neurons by using the derivative of errors with respect to an output neuron weights. For the case study, we apply the proposed method to forecast the component-wise residential load, and compare this results to that of time series forecasting.
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This paper describes a numerical model for the short-term operation strategy of the cogeneration systems. Especially this paper considered various auxiliary equipments used for the effective operation of cogeneration system. Minimum daily operation costs of topping cycle are calculated by using LP. Simulation results of some cases are analyzed and compared each other. Through these simulations the validity of the proposed model considered various auxiliary equipments is verified.
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Recently, the energy situation in Korea has been significantly changed. Rapid increase in electricity demand, tremendous financial need for new power plant construction, and environmental problem have led to search for more efficient energy production and energy conservation technologies. Due to the potential energy and cost savings to both electric utilities and industries, cogeneration will play an important role in the electric power and thermal energy supply in the future. In this study, we present the COGENMASTER computer model for optimal system configuration and economic analysis of cogeneration system. We also present several case studies with this module to analyze Korean cogeneration market. The result of this study will be useful to utility and industrial cogeneration planners for rapid analysis of cogeneration's value under a broad range of scenarios.
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This paper presents a new method for the computation of fault location in multi-terminal transmission lines. This technique based upon the distributed model of transmission lines to overcome the problems encountered in traditional approaches. This method uses, the magnitude of the differential currents at each terminal and also uses an algorithm an equivalent conversion from an multi-terminal to a 3 terminal system.
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This Paper Presents a practical approach to evaluate the reliability indices of electric distribution systems. The use of reliability evaluation is placed with the framework of distribution system planning. In this paper, the reliability model is based on an analytical method, connecting component failure to load point outage each section. five case studies are reported in the paper. These are to study the effect of varying failure rates and repair times on distribution feeders. The results of a study on sample system are presented in this paper.
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A novel UHS relaying algorithm using reflection coefficients estimation is proposed. Based on a travelling ware approach the algorithm can determine the fault location in a travelling time of the protected lone. The discrimation of the reflected wave from others is possible observing the difference of two coefficients. The algorithm is tested using results determined by EMTP.
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In this paper, an expert system is proposed to deal with restoration problem in a unmanned substation to improve the reliability of power supply and the efficiency of power system management. The proposed expert system searches a switching sequence to rectorate the blackout region using heuristic rules and displays the operation sequence. The expert system uses the X-window on UNIX for the graphics of the expert system. The proposed expert system show a promissing result to a future application.
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This paper presents the method of estimating integral coefficients of new distance relaying algorithm for transmission line protection. The proposed method is based on the differential equation calculates impedance value by approximation of integral term of integro-differential equation which relate voltage with current. As a result, we can determine the integral coefficients in least square error sense in frequency domain and we take into consideration the analog filter characteristics and frequency domain characteristics of the system to be protected. The simulation results showed that these coefficients can be successfully used to obtain impedance value in distance relay.
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The simulation of reactive power compensation in 5-bus and 25-bus system was conducted using transmission-line loss system identification method. Sensitivities of maximum load-power with respect to reactive power compensation was identified by the simulation. With sufficient reactive power compensation at the first voltage-collapsing load-bus, the first voltage collapse could be prevented until the next voltage-collapsing load-bus lost its voltage stability. And the total compensated reactive power at the first voltage-collapsing bus means reactive power margin of voltage collapse or distance to voltage collapse. This quantity can be useful for determining the size of compensating devices or the site to compensate.
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In this paper, the optimal fuzzy controller of exciter and governor in synchronous generator improve the stability of power system with varying loads and disturbances in power system. Parameters of the proposed fuzzy controller were optimally self-tuned by the steepest descent method and were applied to power system stabilization. The related simulation results show that the proposed control technique are more powerful than the conventional ones for reductions of undershoot and for minimization of settling time.
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Recently, advanced digital protection relays were developed in Japan. This improved relaying system for the next generation is expected to have higher performance for the discrimination of the fault, functions for multi-purpose use of acquired data, easy operation and maintance, and also have friendly man-machine interface. This paper describes the system configuration of the developed relay and its representive characteristics.
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The cause of black out of Tokyo Power in 1987 has been identified as the voltage stability problem. After this event many researchers has been interested in voltage stability or voltage collapse phenomena. The voltage instability is different Com the transient stability in the sense of reactive power mismatch and the long duration time. In this study, we developed efficient tool for analyze and control the dynamic voltage instability. To analize specific condition of dynamic voltage stability, quasi-dynamic simulation method is developed. To provide proper mathmatical model for dynamic voltage stability, generator, SVC, OLTC, induction motor models are introducted. To provide specified dynamic voltage stability, the authors considered to use reactive loss function(
${\partial}Q/{\partial}p_L$ ) as reactive power facility control index. This program was tested and identified its usefulness in real KEPCO system. -
Accurate estimation of soil resistivity parameters are very important in the design of grounding systems. This paper presents a useful methodology for the optimal estimation of soil parameters based on the weighted least square concepts using a set of earth resistivity measurements by Wenner method. And, this paper developes a computer simulation programming for the estimation of soil parameters. Results are presented and compared with the results of other methods.
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This paper presents the structures, characteristics and shield factor of armoured communication cables used against power induction problems. The decision methods of grounding resistance and calculation formulas of shield factor are considered and improvement methods of domestic installation practice are presented.
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The objective of this paper is to present a systematic approach to detect and classify automatically Power Quality Disturbances by applying the recent advances in digital signal processing techniques including wavelet theory and neural networks. To demonstrate the validity of the derived result, computer simulation results are included.
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This paper presents a linear quadratic gaussian(LQG) based power system stabilizer(PSS) to control subsynchronous resonance(SSR) that occurs in a series capacitor compensated power systems. The complete SSR system based on the IEEE first benchmark model is employed in this study. Eigenvalue analysis and time domain simulations using a nonlinear system model show that the proposed PSS controls SSR efficiently.
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This paper presents a method of obtaining transmission network equivalents from the network's driving-point admittance characteristic. Proposed method is based on modal decomposition representation for the large-scale interconnected system. As a result, Norton-type of discrete-time filter model can be generated. It can reproduce the driving-point admittance characteristic of the network. Furthermore proposed model can be implemented into the EMTP in a direct manner. The simulation results with the full system representation and the developed equivalent system showed a good agreement.
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Conventional methods for root finding of the algebraic equations are intrinsically synthetic division methods, i.e., which are the factorization in forms of
$f(x)=(x-x_i)Q(x)$ . So existing methods have some demerits such as deflation and root-polishing procedures. To overcome these defects a new powerful algorithm, namely circular arithmetic algorithm(CSM), was introduced and has been investigated about its fascinating properties. In this paper, we will propose a simple and effective method of getting the initial guesses for the roots of the equation. With this method the CSM can me all the root of equation with great efficiency. -
This paper describes the dual mode control of the LDM(Linear DC motor) for carrier. The dual mode control consists of seek and analogue control. In seek mode, LDM is moved in the shortest time by switching line, and in analogue mode keeps at origion with high accuracy. We proposed different switching line method according to driving direction.
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In this paper, we present the design procedure and analysis the fundamental characteristics for Linear DC motor using permeance method and finite element method. Designed LDM is made of two permanent magnets, three iron core and amateur windings. For the design the LDM, first of all it is nessary to calculate the air gap flux density and thrust force, after that to determine core size, the numbers of winding turns, winding width, motor cross section area and losses in the coil. Also, we analysis the fundamental characteristics for implemented LDM according to proposed design procedure, and we find that the implemented LDM generated constant thrust force for costant current as long as iron of core is not saturated. Finally, we find that the proposed design procedure in this paper is effective to design and implementation of LDM.
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The Development of A.C. Induction Motor for Railway Rolling Stock. The traction motor is designed as 4-pole induction motor with self ventilation. The winding insulation is throughout of materials of class H. The rotor is designed as a squirrel rotor with copper bar. The rotor speed is detected by means of a speed sensor.
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In designing defibrillator several points must be considered such as patient's transthoracic impedance, output energy level, peak current, tine duration of current waveform. Patient's transthoracic impedance depends on patient respectively and the health condition of patient. In this study, before the hardware implementation of defibrillator we determine the range of parameter values of circuit elements to derive optimal discharge waveform by predicting and analyzing the performance of designed circuit.
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This paper describes a method of predicting current, magnetic flux, inductance and torque of switched reluctance motor(SRM) using finite element method with time step considering exciting voltage.
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Shaft position sensing is essential in Switched Reluctance Motor(SRM) in order to synchronize the phase excitation pulses to the rotor position. In low cost application, particularly at low power level, the shaft position sensor is too costly. This paper describes low cost SRM drive system that can control torque and speed utilizing a optointerrupter with slotted disc. The validity of the proposed scheme is verified by experimental results for 6/4 SRM drive system.
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This report describes CRDCM(Counter Rotating DC Motor) that we have designed, manufactured and tested. CRDCM have two rotating rotors: one is a outer rotor as field set, another is a inner rotor as armature set. One of the most difficult problem is an elimination of the centrifugal force acting on brush when outer rotor is rotated. We solved a problem for centrifugal force of commutation brush by compensation set of counter mass through trial and error. It was verified the performance of motor at present.
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In this study, electrical stress of the steep-fronted surge voltage which is distributed into motor winding in switching has been analyzed by multiple-conductor transmission equation. We see that the greatest electrical stress appears at the last turn of the first coil of motor.
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This paper focuses on the dynamic interaction between travelling vehicle and flexible guideway rail system. From a numerical analysis on the simply supported beam vibration excited by a sequence of magnetic force, we studied the dynamic response of MAGLEV.
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For the analysis of characteristics of a superconducting transformer, we designed and fabricated a 5kVA superconducting transformer with two kinds of secondary winding. Using the results of the open and short tests, we calculated the parameters of its equivalent circuit. We designed also a 5kVA conventional transformer with the same design conditions as the superconducting one. The performances of the superconducting transformer were compared with the performances of the designed conventional transformer and another 5kVA distribution transformer.
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Recently a superconducting fault current limiter(SFCL) has public attentions for the solution of large fault currents of power systems. Though a SFCL has more effective characteristics than the other current limiting devices, there are many problems to apply it to real power systems. For the analysis of transient fault characteristics of the SFCL, we designed and fabricated a inductive SFCL and tested it in 35V line. The superconducting cable of the SFCL was quenched at lower current(49A) than the designed critical current but it limited the fault current to the lower value(150A) than the one expected without SFCL(250A). And within one period the fault current decreased lower than normal laod current.
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While the projectile in the induction type coil guns is in motion, there exists an induced current in the sleeve coils of the projectile. The motion includes not only the z-axial movement but transversal movement. The projectile in coil guns, which is not supported physically, gets a force in the transversal axis to have a motion in this axis. As a result of this motion, sleeve effects are exhibited to the projectile. This paper presents the analysis of the secondary effect especially due to the propelling velocity of the projectile.
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The purpose of this paper is to describe the mutual inductance between two non-coaxial circular coils in coil gun. As being in many electromagnetic applications, one of them is fixed and the other one is moving and, being not supported, its axis may not coincide with the axis of the fixed coil. This paper presents a method for the calculation of the mutual inductance in case of non-coaxial coupled coils, the characteristics of this inductance and experimental results. For the computation, the complete elliptic integrals formula and mesh matrix technique were introduced. This method enables accurate results from relatively simple procedure and calculation program.
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We have developed a stabilizing SMES with 0.5MJ energy storage capacity through all the research process of the system planning, magnet drawing, which including various kinds of evaluation for the optimized system organization. This research performance is considered to be very distinguished one. Besides, the acquired knowledge and many experiences getting through the performance of the study are much benefitful to other studies concerning with a development of superconducting electrical power machines. This paper gives the general presentation of the study and many kindes of expermental results including analysis of them.
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Recently, a Deflection Yoke(DY) is designed in the bobbin-seperator-coil-winding type for high-definite CRT and high-efficient DY of wide vision TV or High Definite TV. This paper presents an optimization or bobbin-seperator-coil-winding type yoke's coil distribution for minimizing gap between desired and practical deflections of electron beams using by Evolution Strategy.
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It this paper, a single-phase high power factor rectifier with low-enery requirements for filtering elements is proposed. By switching control, the current containing the 3rd-hamonic component is to flow into the rectifier. Properly selecting the amplitude of the 3rd-hamonic component, it is possible to reduce the stored energy in the rectifier. Boost converter is used for power-factor control while active filter absorbs the 3rd-hamonic component. Simulation results are presented to show low stored energy of the proposed rectifier.
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In this paper, a three-phase active power filter using voltage- source PWM converter is designed to eliminate the harmonics and compensate the reactive power in the ac side. The predictive current control method is adopted, which provides constant switching frequency and low current ripple but has inherently one sampling error between the command and the actual current. Here we propose the algorithm which corrects this delay time. The converter voltage obtained from this current control can be accomplished by the space vector modulation method at a voltage-type converter. All control sequences of active filter is executed by a DSP which is designed to calculate floating points at very hight speed. Finally, the validity of this filter using the predictive current control method is demonstrated through experimental results.
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The pulse width modulated class D power amplifier has the highest efficiency among various class amplifiers but the performances, such as bandwidth, distortion and stability are inferior to the conventional ones. In this paper, a new class D amplifier design is Presented employing dual feedback loops namely current and voltage feedback. The new design provides wide full-power bandwidth and stability at any load with high efficiency.
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In this paper, the authors propose a so-called new soft switching circuit topology. The resonant circuit in new converter implements zero-current and zen-voltage for power switches without increasing voltage/current stresses. The proposed converter are deemed most suitable for high-power applications where the power switching devices are used. Some simulative results on computer are included to confirm the validity of the analytical results.
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Binary control with integral COFB is presented to alleviate the chattering. Binary control system consists of the main loop and the external loop which transforms the gain of main loop smoothly, and can generate the continuous control input under the existence of the delay and the switching frequency limitation of the controller. Therefore, it has the properties of chattering alleviation, in addition, advantages of the conventional variable structure control. To confirm the validity of the developed controller, position control of brushless DC motor with binary controller as a position controller is performed.
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This paper deals with the parallel operation of inverters. To enlarge capacity of inverter system and reduce current ripples on inverter output side, two or more inverters are operated in parallel. Up to now six-step inverters and sinusoidal PWM inverters are considered in parallel operation, but using space-vector PWM inverters we can get many advantages of reducing ripple current energy and torque ripple and so on. As we can choose effective voltage vectors more freely than single operation, inverter output current ripples can be reduced by shifting beginning and end point of switching state back and forth.
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This paper presents a new low loss snubber including the overvoltage snubber for three-level GTO inverters. The proposed snubber can not only minimizes the snubber loss and the number of components but also improve blocking voltage balancing problem between the inner and the outer GTOs.
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In recent days, the various adjustable speed drives are widely employed at the industrial applications for the purpose of energy saving and speed control. In particular, for the machine control applications. the switching frequency is required to be increased for better dynamic performance of the drive. Moreover, this also leads to the reduction of the switching loss of the device. For IGBT (Insulated Gate Bipolar Transistor), the most widely used switching device in the inverters below the 100[kW] range, the falling and falling time is of the order about
$200{\sim}300[ns]$ . Therefore unexpected phenomena occurs such as voltage spikes due to high gradient of current at the switching instant, the weakening of motor insulation due to high gradient of voltage. In this paper, a new voltage gradient suppression technique is presented in both theoretically and experimentally. -
A new control technique which generates high-quality sinusoidal output voltage from a single-phase resonant do link inverter suitable for the UPS systems is presented. The inverter output voltage control system has the PID controller with a minor loop of the filter inductor current and tile feedforward controller. The proposed control scheme also solves resonant voltage overshoot without any additional switch or passive component, resulting in pulses with uniform amplitude and high efficiency. Experimental results in the case of linear and nonlinear loads are presented to confirm the usefulness of the Proposed control algorithms.
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This paper proposes a servo control system of brushless motor at a low and high speed range. The control system is composed of the PI controller for high-speed control and the modified PI controller for low-speed control and the current controller using the hysteresis current control PWM method. The speed control performance is shown by the computer simulation.
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The paper deals with the fuzzy PI control of a switched reluctance motor drive. Fuzzy algorithm based on linguistic rules describing the operator's control strategy is applied to speed control of the SRM. Simulation and experimental results show that performance of the furry PI controller is superior to that of conventional PI controller. In particular the robustness of the system is improved.
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This paper suggests a SRM control scheme driven by a variable voltage source. This scheme shows that it is unnecessary to introduce a switch to control dc-link voltage and to limit a phase current. And its vary easy to build-up flat-topped phase current which is advantageous to the high torque and efficiency drive of a SRM. Experimental tests are shown to verify this suggestion.
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Due to the environmental considerations and the energy crisis, there has been a revival of electric vehicles since 1960s. Research and development work concerning with electric vehicles (EVs) was becoming more intense in last decade. As compared with conventional internal combustion engine (ICE) cars, EVs have the advantages of clean, quiet, better energy efficiency, less maintenance and improving the load factor of electric power systems. However, EVs usually have a snort running range, bad acceleration performance and high initial cost. The main reason for these shortcomings is the low figure of energy density and the high per energy cost of battery at present technology state. So it is very important to optimize the overall drive system design with respect to the maximum utilization of battery, energy, motor torque and inverter power. This paper describes a demonstration model of electric car which is driven by 4-wheel direct method using the vector control.
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In the overmodulation region, the operation of the three phase induction motor with a current controller is characterized by a rapid deterioration of the motor torque and speed. It is desirable to use the overmodulation strategy that extends the normal operating range even in this case. In this paper, a new overmodulation strategy is proposed for the high performance motor drives and the comparison study with two conventional methods are also described. In the proposed strategy, considering the motor dynamics, a suitable voltage vector is selected in order to extend the stable operating range in the overmodulation region. With this advanced overmodulation algorithm, the normal operating range can be extended without any extra hardware.
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In recent days, the inverter is widely used at the industrial applications. In the range lower than 100[kW], IGBT(Insulated Gate Bipolar Transistor) is most widely used as the switching device. In that case of IGBT, the rising time and the filling time are very short(about
$200[ns]{\sim}300[ns]$ ). Especially for motor control applications, the switching frequency is required to be increased for better dynamic performance of the drive. However, the higher switching frequency leads to the unexpected problem occurs such as voltage spike due to stray inductance in the bus at switching instant. In this paper, a new methodology for reducing the stray inductance existing in the bus that induces the voltage spike will be presented. -
This paper presented the developments and operations of control system for Inverter-controlled air pressure type water-supply systems. The developed controller that enables regular speed and variable speed. In addition, an air supplement control system was developed to establish a utility model of water supply facility system as well as a method to optimize its operation.
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Lead-acid battery is used widely as a power source at a automobile, industrial machines, folk lifts, U.P.S. etc. Since lead-acid battery is cheaper than any other ones. But this battery has many disadvantages such as heavy, low energy density, environment problem etc. In this article, we introduce potential step methods to investigate corrosion behaviour of positive grids for lead alloys.
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Microwave dielectric properties of
$0.15(Ba_xSr_{0.05})O-0.15(Sm_{2(1-y)}Nd_{2y})O_3-0.7TiO_2$ ($x=0.9{\sim}1.0[mol.]$ , y=6[m/0]) and$0.15(Ba_{0.95}Sr_{0.05})O-0.15(Sm_{2(1-y)}Nd_{2y})O_3-zTiO_2$ (y=6[m/o],$z=0.66{\sim}0.7[mol.]$ ) ceramics were investigated with the contents of BaO and$TiO_2$ . In the specimen with contents of BaO (0.975[mol.]), dielectric constant, quality factor and temperature coefficient of resonant frequency have good values of 76.52, 3001(at 3[GHz]), +0.71[ppm/$^{\circ}C$ ], respectively. In the specimen with contents of$TiO_2$ (0.69[mol.]), dielectric constant, quality factor and temperature coefficient of resonant frequency showed the maximum values of 80.89, 3057(at 3[GHz]), +26.12[ppm/$^{\circ}C$ ], respectively. -
In this study, the structural, dielectric and piezoelectrical properties of
$xPb(Mg_{1/2}W_{1/2})O_3-(1-x)[0.41Pb(Ni_{1/3}Nb_{2/3})O_3-0.36PbTiO_3-0.23P Zr)_3]$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated. The dielectric constant${\varepsilon_{33}}^{\tau}$ at loon temperature increased up to 3mol% PMW and decreased with further PMW content. The specimen with 1mol%$Pb(Mg_{1/2}W_{1/2})O_3$ , which has the${\varepsilon_{33}}^{\tau}=5509$ , kp=59[%] and$d_{33}=758{\times}10^{-12}[C/N]$ , exhibits good characteristics. -
The dielectric and electrical properties of
$Pb(Mg_{1/3}Nb_{2\3})O_3-PbTiO_3-BaTiO_3$ have been investigated. Perovskite crystalline phase of the specimens are confirmed by XRD at$1270^{\circ}C$ . The curie temperature is around$40^{\circ}C$ with the amount of$BaTiO_3$ and$PbTiO_3$ . Every specimens shows the slim loop hysteresis curves which is electrostrictive characteristic. The strain vs. applied voltage characteristics exhibits nonlinear relationship, and the specimen of 0.85PMN-0.125PT-0.025BT shows the largest strain. -
The switching characteristics of
$As_{10}Ge_{15}Te_{75}$ thin film were investigated under dc bias. It was found that the threshold voltage depends on thickness, electrode distance, annealing time and temperature, respectively. The threshold voltage is increased as the thickness and the electrode distance is increased, while the threshold voltage is decreased in proportion to the increased annealing time and temperature. -
Nowadays Perovskite
$La_{1-x}Sr_xCoO_3$ is a preferred cathode material in the construction Solid Oxide Fuel Cell (SOFC). The$La_{1-x}Sr_xCoO_3$ with Sr contents ranging from X=0.0 to X=1.0 were prepared by a citrate method. All samples were examined by X-ray powder diffraction. The samples used for measuring thermal expansion were prepared as pellets by cold pressing and subsequent sintering in air at$1200^{\circ}C$ for 5 hours. To measure the sub-product of$La_{1-x}Sr_xCoO_3$ with YSZ, where coating films were sintered at$1200^{\circ}C$ for 5 hour. -
The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. PEO-
$LiClO_4$ electrolyte with plasticizer is very unstable. Passivation phenomena in polymer electrolyte cell was described by the SPL model. The time dependance of the impedance indicates that a passivation layer grows rapidly on the Li surface. However, the growing of passivation layer on the Li surface can be restrained by addition of zeolite to the PEO electrolyte. It suggested that addition of zeoliteto to the PEO-$LiClO_4$ electrolyte effectively controls the formation of a passivation layer on Li electrode. -
X/65/35 PLZT ferroelectric thin films were fabricated by sol-gel processing. Thin films were crystallized after rapid thermal processing at
$750^{\circ}C$ for 5 min. The microstructure, the relative dielectric constant the curie point, the hysteresis curve and the optical transmittance of thin films were investigated. -
At recent time, superconducting technology makes it possible to develop various devices using strong magnetic fields. As increasing with devices using high magnetic fields, magnetic shielding technology is essential in order to get high efficiency. Therefore it is necessary to establish production method and clear characteristics of suitable shielding materials. Usually, ferromagnetic metal has been used for shielding of high magnetic fields up to the present time. Instead of heavy ferromagnetic metal, we can acquire better upgraded shielding system by using of very light superconducting thin film that has a perfect diamagnetism. We would like to study basic characteristics of NbTi thin film produced by RF sputtering, investigated morphology and crystal structure of NbTi thin film by SEM and XRD, identified superconductivity measuring by critical current.
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$(Sr_{l-x}{\cdot}Ca_x)_mTiO_3+0.006Nb_2O_5$ ($0.05{\leq}x{\leq}0.2$ , 0.996$N_2$)에서 소결시킨 후 CuO를 시편의 양면에 도포하여 $1100^{\circ}C$ 에서 2시간동안 열처리함으로써 제작하였다. 결정립의 크기는 Ca의 치환량이 증가함에 따라 촉진되었으나, 20[mol%] 이상 치환시 더 이상 고용되지 못하고 입성장을 억제시켰다. Ca의 치환량이$10{\sim}15[mol%]$ , m=1인 시편에 있어서 우수한 유전특성을 나타내었다. 즉, 비유전율, 유전손실($tan{\delta}[%]$ )과 온도변화에 따른 정전용량의 변화율이 각각 >25,000, <0.3[%], <${\pm}10[%]$ 을 나타내었다. 본 연구에 사용된 모든 시편은 온도의 함수로서 주파수 증가에 따라 유전완화 현상을 나타내었으며, 분산주파수는$10^6[Hz]$ 이상이었다. -
Oil-soluble poly(p-phenylene(1-methoxyethylene)), as a precursor of poly(p-phenylenevinylene) (PPV), was synthesized add identified with NMR and FT-IR spectroscopy. The PPV films were prepared by PPV precursor films with a thermal treatment at
$250^{\circ}C$ under vacuum, where the PPV precursor films wets formed on various substrates by using Langmuir-Blodgett(LB) method. The characterization of these films was carried out by FT-IR spectroscopy, UV-VIS absorption spectroscopym, and photoluminescence (PL). Atomic Force Microscopy (AFM) has been used to investigate He surface morphology of PPV films. -
This paper describes the optimum conditions for depositing PAAS(polyamic acid alkylamine salts) Langmuir-Blodgett (LB) films, which are a precursor of polyimide LB films. The optimum conditions were studied by
$\pi$ -A isotherma with a varication of temperatures, spreading amounts or solution, compression speeds, and etc. Transfer ratio was also measured depending on the type of LB films. -
The second-order nonlinear optical effect, especially the second harmonic generation, in Langmuir-Blodgett(LB) films have get much attention over the past few years. For second harmonic generation(SHG) of the ultrathin organic films, the multilayer structure of the film should have the noncentrosymmetric arrangements of molecules. The Langmuir-Blodgett technique can result in the production of thin films of precisely controlled dimensions and structure. In this paper, n-octadecyl 4-(4'-nitrophenylazo)-1-naphthyl ether, ONNE(azohenzene derivative), was synthesized and the optical properties of ONNE was studied. Nonccntrosymmctric Z-type LB films of ONNE were prepared and SHG intensity of the film were measured. The structural characteristics of floating monolayer(L film) and LB film of ONNE were discussed with
$\pi$ -A isotherm. UV-visible absorption spectroscopy and spectroscopic ellipsometry. The polarized UV-visible absorption spectroscopy and SHO intensity suggest the molecular orientation in LB film. -
A Spotter ion Plating(SIP) system with a r. f. coil electrode and the Facing Target Sputter(FTS) source was designed for high-quality thin film formation. The rf discharge was combined with DC facing target sputtering in order to enhance ionization degree of a sputtered atoms. The discharge voltage-discharge characteristics curves of a FTS source could be characterized by the fern of
$I{\propto}V^n$ with n in the range of$8{\sim}12$ . The energy of ions incident on the substrate depended on the sheath potential of DC biased substrate. The mean impact ion energy increased with negative bias voltage and rf power. The adhesive force of the TiN film formed was in the range of$30{\sim}50N$ , and markedly influenced by substrate bias voltage. -
We have studied a properly of N-docosyl pyridinium(TCNQ) Langmuir-Blodgett film at room temperature with the
$NO_2$ gas-detection characteristics. As a result, we have found that their conductivities were increased by 6 times at 5 layers(about$250{\AA}$ thickness) LB film. However, their reproducibility was not able to be measured at room temperature. Therefore, we must find their working temperature which was able to activate gas-detection characteristics. The$NO_2$ gas response experiments under 200 ppm concentration in$50^{\circ}C$ show that :here are increment of electrical conductivity by 8 times and 100 seconds of response time, and 200 seconds of recovery times at$60^{\circ}C$ . -
We fabricated Au/PI/Pb and Au/PI/1-layer Arachidic acid/Pb structures in order to electron transport properties through the junctions. It was found that 9-layer PI LB films function as a good tunneling barrier from the I-V properties. And several peaks originating in the vibrational modes of the constituent molecules of 1-layer arachidicacid LB films were clearly observed in
$d^2V/dI^2-V$ curves. -
The
$NO_2$ gas-detection characteristics were investigated using the functional organic Langmuir-Blodgett(LB) film of Tetra-3-hexadecyl-sulphamoylcopperphthalocyanine(HDSM-CuPc). A surface pressure of 30mN/m was obtained as a proper one for a film deposition. A deposited film status was confirmed by electrical and optical methods such as UV/visible absorption spectra and current-voltage(I-V) characteristics. The$NO_2$ gas response experiments under 200ppm concentration show that there is not increment of electrical conductivity in room temperature and is identified by UV/visible absorption spectra. But There are some increments of electrical conductivity in$160^{\circ}C$ . -
Spectroscopic ellipsometry(SE) was employed to characterize the Si/
$Si_{1-x}Ge_x$ heterostructure. The dielectric function spectrum of$Si_{1-x}Ge_x$ at an arbitrary x value in the spectral range of$1.5{\sim}4.5\;eV$ was computed by EMA (effective medium approximation) model using the available optical constants measured at a number of fixed x values of Ge composition. The thickness and the Ge composition of$Si_{1-x}Ge_x$ measured by SE was compared with those measured by RBS. DC bias effect on the$E_2$ peak of dielectric function spectra was studied. -
We synthesized the conducting diamond-like carbon films using plasma-enhanced chemical vapor deposition and analysized its characteristics. We obtained the metal-containing diamond-like carbon films using
$CH_4$ , Ar gas and aluminum target. We observed the changes of electrical conductivity, microhardness and surface morphology according to$Ar/CH_4$ ratio, substrate bias and target bias. As the target bias and$Ar/CH_4$ ratio increase and the substrate bias decreases, the electrical conductivity and surface roughness increase. The increase of hardness involves decrease of the electrical conductivity. Metal-containing amorphous hydrogenated carbon films show improved adhesion on metal substrates compared to pure diamond-like carbon films and better electrical conductivity. -
The Electrical properties of thin
$SiO_2$ film by rapid thermal processing have been investigated and this film has been compared with thermal$SiO_2$ film by furnace. The RTO(rapid thermal oxide) film annealed in Ar ambient represent more superior properties than thermal$SiO_2$ film by furnace at breakdown field and leakage current. The RTO(rapid thermal oxide) film annealed in$NH_3$ ambient represent more inferior properties than thermal$SiO_2$ film by furnace at electrical properties, but the capacitance was improved 15-25% than the conventional oxide film. -
We fabricated the sample of M-I-M with the insulating layer SiO. Refractive index of wave length, photon energy, absorption rate of SiO evaporation thin film are experimentally examined by spectroscopic Ellipsometer. The calculated equations of refractive index, absorption rate and permittivity of SiO thin film are induced. Calculated values and experimental values are compared and then mutual validity is proved.
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A non-uniform finite-difference Thin Film Transistor Simulation Program (TFTSP) has been developed for hydrogenated amorphous silicon TFTs. TFTSP was developed to remove as many of simplifying assumptions as possible and to provide flexibility in the modeling of TFTs so that different model assumptions may be analyzed and compared. In order to insure its usefulness and versatility as an analytic and design tool it is important for the code to satisfy a number of conditions. However, at the beginning stage of the program development, this paper shows that the code can compute the static terminal characteristics of a-Si:H TFTs under a wide range of bias conditions to allow for comparison of the model with experiment. Some of those comparisons include transfer characteristics and I-V characteristics. TFTSP will be refined to conveniently model the performances of TFTs of different designs and to analyze many anomalous behaviors and factors of a-Si:H TFTs.
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This paper deals with the on off arc characteristics of electromagnetic relay contacts contaminated by NaCl and
$H_2SO_4$ . In this paper, I have studied the characteristics of on-off voltage waveform. the contact errosion, contact surface analysis by SEM and EDAX under changed R-L parameter of testing circuit. After considers these result, I have tried to promote the diagnosis method and developed the contacts. As a results, (1) The arc duration and the numbers of arc occurrence characteristics are depended on contamination degree. The contamination degree is high when the arc characteristics is high. (2) Under clean condition, arc occurrence voltage, surge peak voltage, arc duration and the rate of contact errosion is lower than wet condition. (3) Surge peak voltage and arc duration is depended on L parameter. When L is High, the arc characteristics is high. -
In this paper, we describe the thermal distribution characteristics of 1 phase, 22.9kV 200kVA, pad mounted transformer. We made pad. tr. which had 71 temperature measuring points in windings and case. In the results of pad. tr. temperature distribution, the highest and the lowest temperature points are placed in the high voltage windings and the temperature difference of high voltage winding is higher than that of low voltage winding.
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Various types of plasma display panels(PDPs) have been developed to realize the flat panel display device. But, many of its characteristics must be improved before it can be commercialized. In order to investigate tile characteristics of micro discharge in a PDP ceil, we have constructed a micro-gap discharge system whose electrode gap can be adjustable between
$100-1000{\mu}m$ within$0.1{\mu}m$ accuracy. We measured the minimum sustain voltage, current, delay time of discharge while changing parameters(electrode gap distance, electrode surface area, pressure) which influence discharge characteristics. -
The capacitive current breaking capability as well as the short circuit current breaking capability is a very important factor in the performance of a circuit breaker. The dielectric recovery capability between poles should be considered in the desist of a circuit breaker because approximately two times of the maximum power system voltage might be applied between poles after the capacitive current be interrupted. The electric field and flow field analyses were utilized in the calculation of dielectric recovery characteristics between poles of 800kV model interrupter. The results show that the separation between moving main contact and moving arcing contact will affect to decrease significantly the electric field strength of a moving arcing contact and an insulation cover, to increase slightly the electric field strength of a fixed arcing contact and to decrease consequently the dielectric recovery capability between poles of the interrupter.
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This paper describes a very fast rising high voltage pulse generation for studying surge phinomenon and prebreakdown of liquid dielectric by appling the traveling wave theory of the distributed circuit. This very fast rising high voltage pulse generator consists of a charging coaxial cable, a discharging switch, and a terminating resistance. As results, the rising time of pulses are about 31(nsec), which is very fast, and its duration is 950[nsec] when using 200[m] coaxial cable. The length of the coaxial cable and changing voltage can regulate the duration and the amplitude or the polarity of the pulse. When terminated the resistance, capacitor and inductor, the measured waveform corresponds with simulated waveform.
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The purpose of this paper is to describe an application of plasma polymerized thin film as an electron beam resist. Plasma polymerized thin film was prepared using an interelectrod inductively coupled gas-flow-type reactor. Styrene was chosen as the monomer to be used. This thin films were also delineated by the electron-beam apparatus and the pattern in the resist was developed with RIE and plasma polymerized apparatus. The effect of charge of pressure on growth rate and etching rate of the thin films were studied. The molecular structure of thin film was investigated by FT-IR and then was discussed in relation to its quality as a resist.
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The impedance characteristics of planar ICP have been measured and compared with the theoretical results obtained by the field equation. The resistance of the total impedance had a maximum point and the inductance decreased monotonically as the electron density increased from
$2.5{\times}10^{10}cm^{-3}$ to$7{\times}10^{11}cm^{-3}$ and the Pressure from 1mT to 50mT. The impedance characteristics were also dependent on the profile of the electron density. The effective collision frequency,${\nu}_{eff}$ was$9.0{\times}10^6Hz$ at 5mT and$.5{\times}10^7Hz$ at 100mT. The effective collision frequency at 5mT was not so different from that at 100mT and it is doe to the reduction of the discharge channel cross-section at high pressure. The estimated effective collision frequency from the simulation data was of the same order as the measured one. -
This paper describes the dielectric characteristics of
$SF_6$ gas in non-uniform electric filed under lightning under lightning impulse and oscillating impulse voltages. The breakdown voltage-time characteristics and the breakdown voltage-pressure characteristics are measured over a pressure range extending from 0.1 to 0.5 [MPa] fur the coaxial electrode with a needle protrusion. The curvature radius of needle protrusion is 0.3[mm]. Also, the growth of the predischarge is simultaneously observed. As a result the polarity effect is pronounced, and the breakdowns voltage under the oscillating impulse voltage are higher than those under the lightning impulse voltage. It is found that the breakdown mechanism md predischarge phenomena ate closely related with the polarity and waveforms of the testing voltage. -
This paper deals with the planar-type electric field sensor which can measure the time-varying electric fields. The theoretical principle and design rule of the sensor are introduced, and also the calibration and application investigations are carried out. From the calibration experiments, the frequency bandwidth of the measurement system ranges from 160 [Hz] to 25 [MHz]. At a high voltage laboratory, the electric fields caused by the impulse voltage and oscillating transient voltage are measured by the proposed sensor. Obtained results are well agreement with the applied voltage waveforms.
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This paper presents a methodology for the electric field analysis of substation. For the electric field analysis of substation, the electrodes(substation busbars) must be represented by finite line with nonlinear charge density. In the case of dividing finite line into uniform segments, a large number of variables have to be used to obtain the accuracy within a desired tolerance. To deal with the problem, nonuniform charge arrangement modeling method is suggested. To reduce potential calculation errors, the linear charge density function is considered particularly for the segment charge model ling. If the charge arrangement is improper, the accuracy not improved regardless of increment in the number of segments. This paper proposes an optimal charge arrangement method through potential error analysis. And, the optimal charge arrangement function is formulated by a lot of simulation results.
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Barium Titanate (
$BaTiO_3$ ) is one of the few titanateds which is cubic at room temperature. It has the perovskite structure, high dielectric constant (${\varepsilon}_r=300$ ) and a small temperature coefficient of resistance due to it's Low transition temperature ($Tc=120^{\circ}c$ ). PTCR (Positive Temperature Coefficient of Resistivity) thermistor in thin film$BaTiO_3$ system was prepared by using radio frequency (13.56MHz) and BC magnetron sputter equipment. Polycrystalline, and surface structure characteristics of the specimens were measured by X-ray diffraction (D-Max3, Rigaku, Japan), SEM(Scanning Electron Microscopy: M. JSM84 01, Japan), respectively. Temperature at below$600^{\circ}C$ ,$1000^{\circ}C$ to$700^{\circ}C$ , and above$1100^{\circ}C$ for spotted$BaTiO_3$ thin films showed the amorphous, degree of crystal growth, and polycrystalline, respectively. -
Visual feedback has traditionally been used in robot manipulator control to a limited extent. However in varying environment, visual data is needed to control the manipulator to complete the desired task. In this paper we present a method of manipulator control scheme called image-based visual servo. In this scheme we use image data as feedback to control robot manipulator. And we also show the experimental results with an industrial robot manipulator.
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Jeong, Joon-Young;Kim, Yong-Yil;Kim, Ji-Hyun;Han, Seok-Jin;Kim, Sang-Gweon;Kim, Pan-Dol;Lee, Hong-Won 302
In this paper, we introduce the current implementation status of the absolute position recognition technique using sonars for the navigation of a mobile robot. Using this technique, we have developed the supervisory controller of the autonomous vacuum cleaning robot which can recognize the user-specified origin, moves its body to the origin, and follow the specified trajectory starting from the origin. With the satisfactory results, we expect the autonomous cleaning robot to be commercialized in a very near future. -
In this paper, the desist and the implementation of a robust adaptive controller for trajectory tracking control of the robot manipulator is presented. The proposed control scheme ensures that without any prior knowledge of the robot manipulator parameters, tracking errors are converged to some boundary in the presence of a state-dependent input disturbances as well as the ideal case. The 3 DOF robot manipulator including actuator dynamics is used for the implementation of the proposed control scheme. The experimental results show that the proposed control scheme is valid for trajectory tracking control of the robot manipulator.
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Position control for robot manipulator may not suffice when any contacts are made between the end-effector and various environments. Therefore interaction forces must be controlled in tasks performed by robot manipulator. In general, there are two types of force control for robot manipulator. One is a stiffness control and the other is a hybrid position/force control. Stiffness control is that environment can be modeled as a spring and utilizes the desired normal force to determine the desired normal position. Hybrid position/force control, however, can be used for robot manipulator to track position and force trajectories simultaneously. This paper will compare the result of the hybrid position/force control method with that of the stiffness control method.
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RC(Rod Consolidation) technology in spent nuclear fuel management is an essential method and requires remote operation due to radiation exposure. Its technology may provide an effective means to double the storage capacity of spent fuel storage space. So development of this technology will provide a valuable contribution to establishing economical as well as technological basis for future spent fuel management.
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The operation of RC(Rod Consolidation) technology carry out highly radiation environment. It requires remote operation and automation for efficient handling and for minimizing radiation exposure to the operator. So we investigated up and down position control of shock absorber device in RC system. To verify the research experimentally, a RC system was set up and PI control method was applied. Fuzzy control method was also tested to further improve control behavior.
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When a few eigenvalues and eigenvectors are desired, Rayleigh Quotient Iteration(RQI) is widely used. The ROI, however, cannot give maximum or minimum eigenvalue/eigenvector. In this paper, Modified Rayleigh quotient Iteration(MRQI) is developed. The MRQI can give the maximum or minimum eigenvalue/eigenvector regardless of tile initial starting vector.
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Mareel and Bitmead proved the presence of chaotic signal in random noise by applying dead beat control theory to adaptive mechanism. In this paper robust adaptive theory is proposed. With the property of chaotic signal that has order and law, the proposed theory can enhance the control Performance by applying the recursive algorithm that uses dynamic relation which have small correlation. The performance of proposed algorithm is demonstrated with the computer simulation of position control of electric motor. In this simulation, the adaptive low is adopted to control electric motor and the Presence of chaotic signal in feedback signal is proved by using several method such as time series, fourier spectrum phase portrait method.
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A modified Kohonen's simple Competitive Learning(SCL) algorithm which has binary reinforcement function and a constant adaptation gain is proposed. In contrast to the time-varing adaptation gain of the original Kohonen's SCL algorithm, the proposed algorithm uses a constant adaptation gain, and adds a binary reinforcement function in order to compensate for the lowered learning ability of SCL due to the constant adaptation gain. Since the proposed algorithm does not have the complicated multiplication, it's digital hardware implementation is much easier than one of the original SCL.
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In this paper, we present a speaker-dependent Korean Isolated digit recognition system. At the preprocessing step, LPC cepstral coefficients are extracted from speech signal, and are used as the input of a Frequency Sensitive Competitive Learning(FSCL) neural network. We carried out the postprocessing based on the winning-neuron histogram. Experimetal results Indicate the possibility of commercial auto-dial telephones.
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This paper proposes a robust active noise control (ANC) system. The system constructs filter with a standard model. An adaptive litter, connected to the system in parallel, compensates the modeling error. When the adaptive filter does not work, the proposed system is robust while the conventional system loses the noise control capability. But proposed ANC system shows that the performance is comparable with that of the conventional ANC system under normal conditions.
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The correlation tracker developed by John M. Fitts in 1979 is the most complex to mechanize but provides the best tracking performance in a low SNR condition. Correlation tracker would rewove the requirements for optimizing threshold and has no need to know information about the target. But if the displacement of the target is large, the tracking error of the correlation tracker tends to diverge. In this paper, we suggest a precision image tracking algorithm which improves the tracking performance via iterative application of the matched filter estimation algorithm.
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This paper presents a Fuzzy-PID controller based on Fuzzy logic. Up to now PID controller has had the difficulty of obtaining the optimal gain, and Fuzzy controller has had the difficulty of determining scale factor affecting the performance of control. So that a Fuzzy-PID controller is presented here self tuning of the scale factor and optimal gain. The results of simulation show a good performance in comparison with Ziegler-Nichols controller, having the generality of determining the components of scale factor in Fuzzy rule.
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This paper presents a design technique of SOFLC(Self -Organizing Fuzzy Logic Controller). It is composed of three parts: FLC(Fuzzy Logic Controller) part, RPO (Repeat Parameter Organizing) part, and RTPO (Real Time Parameter Organizing) part. The FLC part is controlled by initial parameters (
$a_1$ ,$a_2$ ,$a_3$ ,$b_1$ ,$b_2$ ,$b_3$ ) the RPO part improves parameters by evaluating the performance of control responses controlled by FLC, and the RTPO organizes the parameters for real time in order to have the same value of the control response($y_k$ ) and the target response($y_k\;^*$ ). -
A real-time collision avoidance algorithm for an AMR (Autonomous Mobile Robot) using the Distance Transform and Vector Field Histogram is studied. This approach enables AMR to find a collision-free path with the unknown obstacles. All system parameters including positions of the obstacles can be accepted using a mouse icon and all the obtained trajectories can be displayed on a computer monitor in graphics.
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An object recognition and restoration using ultrasound sensors and neural networks are presented. The planar arrangement of the sensor is used to reduce the interference effects between sensors. The SOFM(Self-Organizing Feature Map) Neural Network and SCL(Simple Competitive Learning) method are learned with the acquired data. Lab experiments were performed that the object can be recognized ed the resolutions of the object can be enhanced by using the small number of the ultrasound array and neural networks.
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This work describes a hardware implementation of a precision image tracking system which employs a CCD camera mounted on pan/tilt device. Unknown translation between two successive images of a moving object is estimated by using a generalized least-squares method. Estimated position error obtained by the tracking algorithm is used to drive DC motors built in the pan/tilt device for the camera to follow the image. An experimental result shows a sub-resolution tracking error for a image moving with a uniform velocity.
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In this paper, to alleviate the effect of approximation error and discontinuous variation of the controller parameters, the variable structure control scheme using neural networks is presented. In the proposed method, the variable structure control rules for each local linear models are designed to reject the effect of linearization error caused by linearization of the nonlinear system. And neural network infer approximate controller gains from combination of local linear control gains. The proposed control methods can be used to control nonlinear systems and it has robust characteristic against system parameter variations and external disturbances.
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This paper propose a Neural - GA-ES DC motor speed controller. The purpose is to achieve accurate trajectory control of the motor speed. A feedforward neural network structure is used for the controller. Genetic algorithm and evolution strategy is used for learning controller. Simulations are performed to demonstrate the effectiveness of proposed genetic algorithm and evolution strategy with neural structure.
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This paper deals with the disturbance attenuation problem for linear systems with real parametric uncertainties. When there are time invariant parameter uncertainties whose sizes are bounded, a less conservative output feedback controller is constructed such that the closed loop system is asymptotically stable and achieves the prescribed disturbance attenuation level for all allowable parameter uncertainties. In order to demonstrate efficacy of the design method a numerical example is presented.
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In this paper, reduced-order
$H_{\infty}$ robust controller is designed for the drum-type boiler system. From the known nonlinear dynamic model, a linearized multivariable model is obtained. To reduce order of robust controller, observer-based proper$H_{\infty}$ compensator is designed. The designed controller has robust property against the influence of sensor noise, system parameter variation and model uncertainty. A good Performance of the designed controller is shown by simulation. -
In this paper, a stable adaptive composite control system consisting of a PID and a fuzzy controllers is designed to control nonlinear systems. In the fuzzy controller, parameters of membership functions characterizing the linguistic terms change according to some adaptive law. Also, parameters of PID controller change according to some adaptive law. These adaptive laws are based on the Lyapunov synthesis approach. Then, it is proved that the closed-loop system using such an adaptive composite control system is globally stable in the sense that all signals involved are bounded and the tracking error converges to zero. We apply this adaptive composite control system to control a nonlinear system.
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In this paper, the fuzzy LMS algorithm where the convergence coefficient is computed by a fuzzy logic controller was proposed. The proposed fuzzy LMS algorithm showed better convergence property and stability than conventional LMS algorithms. The estimation error and misadaptation degree were used for Input of the fuzzy logic controller. In a airconditioning duct case, various conditions were investigated to design active noise controllers. A case with acoustic feedback, the proposed algorithm showed good performances through computer simulations.
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Volume holograms recorded in photorefractive materials can find important applications in optical memories and optical computing systems. One problem with a photorefractive hologram is that it gets erased by the readout light. Nondestructive readout can be achieved by hologram fixing, and several fixing methods have been reported. Fixing is accomplished by thermally activated motion of an unknown ionic defect, which neutralizes the electronic space-charge patterns. At room temperature the ionic patterns are stabilized. When the electrons are partially redistributed by light, a net space-charge pattern appears, and tile fixed hologram can be read out. In this paper, theoretical modeling and some experimental results are presented for thermal fixing of volume phase holograms in photorefractive
$LiNbO_3$ :Fe. Thermal fixing can be done during or after recording and depends on fixing temperature ($100{\sim}200^{\circ}C$ range) and grating length. Fixed Slating can be erased completely at the temperature over$300^{\circ}C$ . Theoretical modeling shows weil the compensation of electronic Slating by ionic grating and is in good agreement with experimental results. In experiments the dependence of thermal fixing on temperatures and grating lengths is investigated. -
Wireless communication has become a hot issue for its simplicity. Using light wave instead of micro wave has many advantages. It is simple to design a circuit because we can make a circuit with discrete components such as photo diode, photo detector, OP Amp[2]. And we can have many communication channels for we can use every frequency domain. In this paper, we design the wireless communication system and analyze the pulse signal. Then using ray tracing technology we simulate the distribution of light beam.
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Optical interconnections are more attractive than electronic interconnections because of their higher speed, freedom from planar constraints, immunity to electromagnetic interference effects and higher interconnection capacity. Volume hologram is one of the best way to implement optical interconnections. Diffraction efficiency and crosstalk effect are very important things for ensuring independent interconnections. Recently, a general systematic method that can handle a large number of superposed volume gratings in anisotropic host material is presented. In this study for numerical analysis of diffraction, above method is programmed in general form near Bragg angle. Diffraction orders for variation of grating strength are determined by comparing with the coupled-mode method. The effects of parameter variation are considered. Parameters include vertical and azimuthal incident angle, wavelength and interaction length. Diffraction analyses are also performed for intra-mode and inter-mode diffractions.
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We are familiar with the holography in these days. For making holography the coherent sources like LASER are used in many fields. But coherent holography has many problems. Coherent holography needs many instrument for practical use like 3-D TV case. In solving the problem we use the non-coherent source. Nowadays many methods like conoscopic holo graphy using anisotropic crystal, shadow casting and interferometric systems are suggested. In this paper we make the hologram using the triangular interferometric systems. [1],[2],[3],[4]. We explain the afocal and double-afocal system which consists of the triangular interferometric system. The holography made in one point and two point cases is imaged on CCD camera and we handle the image data digitally for the reconstruction efficiently. In reconstructing the hologram the Fraunhofer diffraction theory is used. We adopt the rectangular aperture for the convenience of calculation. In the future we must reconstruct the perfect 3-Dimensional object by optical method. For this, we have many problems like resolution problem. We must solve these problem for perfect reconstruction.
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In this paper a feature-based automatic neural network signal classifier is presented, where five neural network algorithms such as MLP, RBF, LVQ2, MLP-Tree and LVQ-Tree are combined in parallel to classifiy various signals from their features, based on the majority vote method. To demonstrate the performance and applicability of the proposed signal classifier, some test results for the classification of synthetic waveforms and power disturbances are provided.
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The voltage drop in distribution path of battery-reserved DC power system can affect the total of battery, cable and electricity costs. To determine an optimum voltage drop in distribution path for minimizing the total cost, battery, cable and electricity costs are represented as a function of the voltage drop, respectively, and are summed up to the total cost. An optimum voltage drop is selected as the value giving the minimum total cost. In this paper, a design technique of optimum voltage drop in distribution path of DC power system is proposed to minimize the total of battery, cable and electricity costs. The design procedure is described and design curve for selecting optimum voltage drop is also presented as a function of distribution distance.
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In order to provide reliable power service and to prevent a potentail hazard and damage, it is important to detect high impedance fault in power distribution line. This paper presents a neural network based approach for the detection of high impedance faults. A time delay neural network has been selected and trained for the fault currents obtained from field experiments. Detection experiments have been performed with the data from four different high impedance surfaces. Experimental results indicated the feasibility of using TDNN for the detection of high impedance faults.
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This Paper Presents a learning strategy for neural networks based on genetic algorithms and evolution strategies. Genetic algorithms and evolution strategies are used to train weights of feedforward neural network to solve problems faster than neural network, especially backpropagation. Simulations are performed exclusive-OR problem, full-adder problem, sine function generator to demonstrate the effectiveness of neural-GA-ES.
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In this paper, a new technique for quantitative estimation of the stress profile along the depth of
$p^+$ silicon films is presented. The$p^+$ silicon cantilevers with various beam thickness and a rotating beam supported by two cantilevers are used for estimating the stress profile of the films. The average of the residual stress distribution is estimated to be 50MPa. Most of$p^+$ silicon films are subjected to the tensile stress, except the region near the frontside. -
In this study, a silicon piezoresistive accelerometer is designed and fabricated using
$p^+$ etch stop layer. The accelerometer consists of a seismic mass and tour cantilevers, and is fabricated mainly by the anisotropic etching method using EPW as an etchant. Eight piezoresistors are properly arranged and connected to make a bridge circuit so that acceleration in only one direction may be measured. The etch stop method is adequate to the mass-production and the precise thickness control of the diaphragms as well, whet compared with the electrochemecal etch stop method. -
A linear actuator using Terfenol-D rod which can accumulate displacement of the rod was fabricated. The diameter of used rod is 12[mm] and the length of it is 75[mm]. It adopts the electromagnetic units as the clamping units. Basic characteristics of the linear actuator such as displacement vs. current, velocity vs. frequency, step size vs. frequency were experimented. When the driving current is 1[A] and 100[Hz], the velocity of the actuator is about 3.5[mm/s]. We discussed the cause of step size's decrease as increasing driving frequency and the solution to the problem.
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A comb drive electrostatic micro gripper was designed and fabricated. We designed it analytically using electrostatic force and cantilever deflection equation. In fabrication, we used LIGA-like technology consisted of Ni electroplating through polyimide patterned by
$O_2$ Plasma RIE and Al sacrificial layer. This micro gripper was designed to handle an optical fiber which is$125{\mu}m$ in diameter. -
A manipulator which can separate dielectric particles (biological cells) was fabricated on a silicon wafer using polyimide and n-type electroplating. It consists of 1024 electrode arrays (
$60{\mu}m{\times}60{\mu}m$ ) and spacing insulator. Positive dielectrophoresis is used for attracting particles. We have the solution of 3-D laplace equation about this device and calculate the force acting on the particles. The solution has spatial periodicity in the x, y directions and decays exponentially in the z direction.