• Journal of the korean Society of Automotive Engineers
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• v.14 no.1
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• pp.38-46
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• 1992

An optimal design technique for minimum power loss in Kopp Ball Variator Continuously Variable Transmission is developed. Kinematic analysis of traction drive contact is performed to find spin for Kopp Ball Variator, and traction force and torque are calculated from mathem atical model of traction drive contact. The objective function for optimal design is total power loss including contact loss and bearing losses. The design contraints are derived from energy balance for input and output power. The formulated optimal design problem is implemented to a non-linear programming algorithm to find minimum power loss. The performance of optimal ly designed Kopp Ball Variator shows that efficiency is increased about 5-10% compare to a commercial unit.

• Journal of Power Electronics
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• v.11 no.6
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• pp.793-800
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• 2011

This paper investigates the operational modes of buck dc-dc converters and their energy transmission methods. The operational modes of such converters are classified in two types, discontinuous conduction mode (DCM) and continuous conduction mode (CCM). In this paper, the critical inductance relation of DCM and CCM is determined. The equations of the output voltage ripple (OVR) for each mode are obtained for a specific input voltage and load resistance range. The maximum output voltage ripple (MOVR) is also obtained for each mode. The filter size is decreased and the minimum required inductance value is calculated to guarantee the minimization of the MOVR. The experimental and simulation results in PSCAD/EMTDC prove the correctness of the presented theoretical concepts.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.565-569
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• 1993

In this paper, a specified number of actuators are selected from a given set of admissible actuators. The selected set of actuators is likely to use minimum control energy while required output variance constraints are guaranteed to be satisfied. The actuator selection procedure is an iterative algorithm composed of two parts; an output variance constrained control and an input variance constrained control algorithm. The idea behind this algorithm is that the solution to the first control problem provides the necessary weighting matrix in the objective function of the second optimization problem, and the sensitivity information from the second problem is utilized to delete one actuator. For variance constrained control problems, by considering a dual version of each control problem an efficient algorithm is provided, whose convergence properties turn out to be better than an existing algorithm. Numerical examples with a simple beam are given for both the input/output variance constrained control problem and the actuator selection problem.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.251-258
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• 1999

This paper is mainly concerned with the development of the ATO(Automatic Train Operation) profile on precision stop controller. The ATO system is used for automatic or driverless operation of a train. In this paper, the algorithm for ATO controller is presented and three speed profiles on precision stop controller are compared. One profile is based on the maximum jerk control, another on the constant control input, and the third on the optimal control for the minimum energy consumption. These profiles are simulated and analyzed in view of the stop time, control input, jerk, propulsion and braking.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.523-532
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• 1999

The studies were carried out to develop an urban forest aromatic bath in the idle space within city area for handicapped persons, patients and city workers, who having less chance to visit the natural forest aromatic bath. The environmental conditions were checked in the experimental double vinyl house where native and exotic aromatic woody and herbaceous plants were growing with minimum energy input in the periods of mid-winter and mid-summer. The growth and photoperiodic responses of the plants to the low and high temperatures were observed during winter and summer respectively. The most of herbaceous plants in the double vinyl house with the controlled minimum night temperature of $-2^{\circ}C$ had no winter injury but did not grow and started the growth in April. The exotic herbs such as Catnip faassen's(Nepeta x faassenia) and Lemon bergamot(Monarda citriodora) grew better in the longer photoperiodic conditions. The growth rates of Abies koreana, Thuja koraiensis and Pinus sylvestriformis in the early spring were affected mainly by the night minimum temperature and less affected by the photoperiodic conditions during winter. The native aromatic herbs such as Robdosia japonica, Molsa punctulata, Agastache rugosa and Codonopsis lanceolata showed stimulatory growth at the 16 hours day-length in case of the high temperature vinyl hose. The height and root collar diameter growth of pine seedlings were inhibited in maxim temperatures over $40^{\circ}C$ during summer.

• ETRI Journal
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• v.32 no.6
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• pp.932-939
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• 2010

In this paper, a fast migration method is proposed. Our method executes local relocation on a model placement where an additional module is added to it for modification with a minimum number of displacements. This method is based on mean-field annealing (MFA), which produces a solution as reliable as a previously used method called simulated annealing. The proposed method requires substantially less time and hardware, and it is less sensitive to the initial and final temperatures. In addition, the solution runtime is mostly independent of the size and complexity of the input model placement. Our proposed MFA algorithm is optimized by enabling module rotation inside an energy function called permissible distances preservation energy. This, in turn, allows more options in moving the engaged modules. Finally, a three-phase cooling process governs the convergence of problem variables called neurons or spins.

• Speech Sciences
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• v.11 no.3
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• pp.131-142
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• 2004

Speaker identification system basically functions by comparing spectral energy of an individual production model with that of an input signal. This study aimed to develop a new speaker identification system from two parameters from the spectral energy of numeric sounds: difference sum and correlation coefficient. A narrow-band spectrogram yielded more stable spectral energy across time than a wide-band one. In this paper, we collected empirical data from four male speakers and tested the speaker identification system. The subjects produced 18 combinations of three-digit numeric. sounds !en times each. Five productions of each three-digit number were statistically averaged to make a model for each speaker. Then, the remaining five productions were tested on the system. Results showed that when the threshold for the absolute difference sum was set to 1200, all the speakers could not pass the system while everybody could pass if set to 2800. The minimum correlation coefficient to allow all to pass was 0.82 while the coefficient of 0.95 rejected all. Thus, both threshold levels can be adjusted to the need of speaker identification system, which is desirable for further study.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1156-1165
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• 2017

A high performance interleaved bridgeless boost power factor correction (PFC) rectifier operating under the critical current conduction mode (CrM) is proposed in this paper to improve the efficiency and system performance of various applications, such as nano-grid systems. By combining the interleaved technique with the bridgeless topology, the circuit contains two independent branches without rectifier diodes. The branches operate in interleaved mode for each respective half-line period. Moreover, when operating in CrM, all the power switches take on soft-switching, thereby reducing switching losses and raising system efficiency. In addition, the input current flows through a minimum amount of power devices. By employing a commercial PFC controller, an effective control scheme is used for the proposed circuit. The operating principle of the proposed circuit is presented, and the design considerations are also demonstrated. Simulations and experiments have been carried out to evaluate theoretical analysis and feasibility of the proposed circuit.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1396-1406
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• 2016

A novel controller design is presented for the recently proposed electric springs (ESs). The dynamic modeling is analyzed first, and the initial Bode diagram is derived from the s-domain transfer function in the open loop. The design objective is set according to the characteristics of a minimum phase system. Step-by-step optimizations of the Bode diagram are provided to illustrate the proposed controller, the design of which is different from the classical multistage leading/lagging design. The final controller is the accumulation of the transfer function at each step. With the controller and the recently proposed δ control, the critical load voltage can be regulated to follow the desired waveform precisely while the fluctuations and distortions of the input voltage are passed to the non-critical loads. Frequency responses at any point can be modified in the Bode diagram. The results of the modeling and controller design are validated via simulations. Hardware and software designs are provided. A digital phase locked loop is realized with the platform of a digital signal processor. The effectiveness of the proposed control is also validated by experimental results.

• Journal of Electrical Engineering and information Science
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• v.3 no.3
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• pp.316-321
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• 1998

In recent years, concern has been raised about the technique of controlling electrical breakdown by using laser in many fields. Especially, laser has attracted much attention in the Electro-Discharge Macining(EDM) because of its many merits. Therefore, this research has been performed to obtain fundamental data relevant to discharge processing by using a pulsed Nd:YAG laser. The experiments of laser-guided dc discharge by laser radiation have been carried out at low air pressure ranging from 0.2 to 20 torr. The minimum laser-guided dc discharge voltage V\ulcorner at the given pressures P and distances D between an anode and a cathode was measured. It is found that the minimum laser-guided dc discharge voltage is much lower than the natural discharge voltage V\ulcorner\ulcorner, and the values of V\ulcorner and V\ulcorner as a function of P.D has a similar tendency. The laser output energy Eout decreases with input pulse duration tp increasing, and the more the value of tp increases, the higher that of V\ulcorner is obtained because the number of photons during the discharge time N decreases with t\ulcorner increasing. There is the time lag frequently when the discharge by laser radiation is misguided under the condition of the applied voltage less than V_G.min.