• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1529-1535
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• 2012

This paper presents the application algorithm for speed control of Switched Reluctance Motor. The conventional PI controller has been widely used in industrial applications. But it is very difficult to find the optimal PI control gain. Fuzzy control does not need any model of plant. It is based on plant operator experience and heuristics. The proposed fuzzy logic modifier increases the control performance of conventional PI controller. Simulation and experimental results show that the proposed fuzzy control method was superior to the conventional PI controller in the respect of system performance. The experiments are performed to verify the capability of proposed control method on 6/4 salient type SRM.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.531-537
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• 2007

This paper presents a new method for determining L, Cs, and Cp in a series parallel resonant inverter. This inverter is suitable for driving high-intensity discharge (HID) lamps. The operating frequency is selected to avoid acoustic resonances which are governed by the size and shape of the arc tube. L, Cs and Cp, are chosen to satisfy the ignition and steady state requirements of the lamp. Equations are developed to analyze the starting condition and steady state operating condition of the lamp. For the prototype ballast for a 250W Metal Halide Lamp, experimental results are presented in order to validate the proposed method.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.21-23
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• 2007

In this paper a high efficiency bi-directional DC-DC converter for hybrid vehicles is proposed. The proposed converter a three-phase half-bridge interleaved ZVS converter, is designed to have high efficiency in the main operation range. The component ratings are calculated, the actual devices are selected, and the efficiency analysis has been performed to determine optimal ZVS range. The input and output current ripples are significantly reduced due to the interleaved operation. The dual loop control for the interleaved three-phase converter is also presented. To confirm the proposed convert ter, The simulation and experimental results are presented.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.595-602
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• 2015

The rotor configuration of the brushless doubly fed induction generator (BDFIG) plays an important role in its performance. In order to make the magnetomotive force (MMF) space vector in one set rotor windings to couple both magnetic fields with different pole-pair and have low resistance and inductance, this paper presents a novel wound rotor type for BDFIG with low space harmonic contents. In accordance with the principles of slot MMF harmonics and unequal element coils, this novel rotor winding is designed to be composed of three-layer unequal-pitch unequal-turn coils. The optimal design process and rules are given in detail with an example. The performance of a 700kW 2/4 pole-pair prototype with the proposed wound rotor is analyzed by the finite element simulation and experimental test, which are also carried out to verify the effectiveness of the proposed wound rotor configuration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.340-343
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• 2007

In this paper, we present our method to reduce vibration of the base plate of a refrigerator by avoiding resonance between base plate and compressor operation. To verify the modes of the base plate, FE models of the base plate with free-free condition and applied boundary condition were built and validated by results from experimental modal analysis. Operating Deflection Shape analysis was applied to find the sensitive area on the base plate during compressor operation. In optimization process, Finite Difference Method - based sensitivity analysis is used to detect the most sensitive area. Finally, based on this numerical result, we will make beads on the base plate to reduce vibration of refrigerator.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.106-114
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• 2003

The pressure ripple in the delivery port is caused by flow ripple, which is induced by variation of pumping chamber volume. The other reason is the reverse flow from the outlet volume produced by pressure difference between pumping chamber and outlet volume, when the pumping chamber is connected with the outlet volume. In this study, a mathematical model is presented for analyzing discharge pressure ripple, which includes vane detachment, cam ring movement , and fluid inertia effects in V-groove in the side plate. From the analysis and experiment, it was found that V-groove on the side plate, coefficient of spring supporting the cam ring, and average discharge pressure are the main factors of discharge pressure ripple in variable displacement vane pump. The theoretical results, provided in this study, were well agreed with experimental results. The analytical model to estimate the magnitude of pressure ripple in this study is expected to be used f3r the optimal design of the variable displacement vane pump.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1775-1781
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• 2007

In this paper, the rotational loss of the superconductor flywheel energy storage system (SFES) by motor/generator stator core was assessed. To do this, the vertical axial type SFES with journal type superconductor bearing was manufactured. To quantitatively assess the rotational loss by the stator core, the rotational losses by superconductor bearing and the degree of a vacuum were measured. In case of variation of the inner radius and outer radius of the stator core, the rotational losses were measured. From the experimental results, It is confirmed that the rotational loss can be reduced by means of the optimal stator core design.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.23-29
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• 1997

In the control of crane system, the traversing time of the trolley must be reduced as much as possible and the swing must be stopped at the end point. To design the minimum time control system, Pontryagim maximum principle is applied. In order to implement the control algorithm, the dynamic equation is linearlized at an equilibrium point, so that the linear time invariant state equation can be obtained. The overall performance of the closed loop system is evaluated by means of computer simulations and practical experiments in a broad range of working conditions. The effectiveness is proved through the experimental results for the anti-sway control of the load and the position control of trolly. It is expected that the proposed system will make an important contribution to the industrial fields.

• Korean Management Science Review
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• v.12 no.1
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• pp.111-124
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• 1995

With the increasing interest of reducing process variation, statistical process control has served the pivotal tool in most industrial quality programs. In this study, system analyses have been performed associated with a cost incorporated version of a process control, a quadratic loss-based X over bar control chart model. Specifically, two issues, the capital/research investments for improvement of a system and the precision of a parameter estimation, have been addressed and discussed. Through the analysis of experimental results, we show that process variability is seen to be one of the most important sources of loss and quality improvement efforts should be directed to reduce this variability. We further derive the results that, even if the optimal designs may be sensitive, the model appears to be robust with regard to misspecification of parameters. The approach and discussion taken in this study provide a meaningful guide for proper process control. We conclude this study with providing general comments.

• The Journal of the Acoustical Society of Korea
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• v.19 no.7
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• pp.23-27
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• 2000

We provide an useful method to design codebooks with better performance than conventional methods. In the proposed method, new codevectors obtained from learning iterations are not the centroid vectors which are the representatives of partitions, but the vectors manipulated by the distance between new codevectors and old codevectors in the early stages of learning iteration. Experimental results show that the codevectors obtained by the proposed method converge to a locally better optimal codebook.