• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.45-50
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• 2013

This paper presents design of induction motor in very low temperature for LNG main cargo pump and comparison of two motors. One is the motor for using in room temperature and another is the motor for using very low temperature. This paper designs with Equivalent circuit Method and uses Finite Element Method to analysis. The motor for very low temperature considers variation of coil resistivity due to temperature change and compare torque characteristic with the motor for room temperature. Design element of motor for very low temperature considers resistivity variation following temperature change on going through this paper. The result shows that two types of motors are almost same torque curve characteristic even though they are not the same environment.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1395-1401
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• 2010

A paradigm shift in driving system of transportation vehicle from engine to electric motor is required as the problems on air pollution and drain of petroleum resource are on the rize. Moreover while it is possible to control the motor with variable frequency driver, the application of motor in various kinds of vehicles is spread rapidly. In the paper, the effective design method of IPMSM for EV and HEV by using equivalent magnetic circuit and finite element method (FEM) is suggested. First of all, load conditions of the application are calculated. And basic design process of IPMSM is proposed with two design point. Finally, in order to verify the proposed design process, it was compared with the basic design parameter and the FEM analysis results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.250-256
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• 2007

We analyzed the effect of a pixel and all the inter-electrode capacitances in a unit pixel of TFT-LCDs on the gray scale capability. The pixel and all the inter-electrode parasitic capacitances were obtained from the tree dimensional profiles of potential distribution and molecular director considering lateral fields generated at the edge of the pixel. To obtain the RMS and kickback voltages of the pixel, we constructed an equivalent circuit of the panel containing all the parasitic capacitances. The calculation was performed though H-SPICE. As results, we confirmed that the pixel becomes smaller, the effect of parasitic capacitances on the gray scale capability becomes larger.

• Transactions on Electrical and Electronic Materials
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• v.8 no.5
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• pp.222-225
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• 2007

In this paper, we compared the current limiting characteristics of both the hybrid type and the flux-lock type superconducting fault current limiters(SFCLs), which have a magnetic coupling structure between a primary winding and several secondary windings. The limiting impedances of two SFCLs were derived from each equivalent circuit considering the design parameters of SFCL such as the self-inductance of secondary winding and the resistance of $high-T_C$ superconducting(HTSC) element. Through the comparison for the limiting impedances of two SFCLs considering the dependence of the HTSC element's resistance on the applying voltage into the SFCL, the hybrid type SFCL was confirmed to have larger limiting impedance with smaller resistance of HTSC element than the flux-lock type SFCL. It was expected from the analysis that the hybrid type SFCL was more advantageous than the flux-lock type SFCL from the viewpoint of the fault current limiting level.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2240-2246
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• 2007

Optically coupled linear isolation amplifier requires special care to avoid oscillation in actual applications. In this paper methods to analyze the frequency characteristics of the amplifier are proposed to reveal the cause of oscillation and to provide design guidelines. The loop gain of the amplifier obtained through the equivalent circuit model shows that the phase margin is too small to ensure stable operations. Methods to get non-oscillatory response are proposed and the resulting frequency responses are analyzed. The common method adding a small capacitor to the amplifier is shown to degrade the frequency bandwidth. The frequency response of output voltage explains the need of filter capacitor in output stage. The usefulness of the method is verified through experiments.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.752-753
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• 2008

The analytical expressions for magnetic field distributions considering slotting effects, cogging torque and back-emf considering skew effects are established. On the basis of magnetic field solutions, electrical parameters such as back-emf constant and winding inductance are obtained. The predicted results are validated extensively by non-linear finite element (FE) analyses. In particular, test results such as back-emf, cogging torque, inductance and resistance measurements are given to confirm the analyses. Finally, generating performances are investigated by applying estimated parameters to equivalent circuit (EC) of the permanent magnet generator (PMG) and validated extensively by FE calculations and measurements.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.118-123
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• 2013

This paper presents performance comparison between concentrated winding and distributed winding of IPMSM (Interior Permanent Magnet Synchronous Motors) which is recently used for light-weight railway applications. Motors are designed on various schemes and analyzed by using FEM (Finite Element Method) instead of EMCNM (Equivalent Magnetic Circuit Network Method) in order to take into account saturation and non-linear magnetic property. The overall performance such as torque, torque ripple, losses, demagnetization, efficiency, power density and so on are investigated in detail at the rated and maximum operating speed. The results of the analysis found that both concentrated and distributed winding IPMSMs are promising candidates for high power railway traction motor.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.860-861
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• 2015

본 논문에서는 대용량 착자요크의 설계과정에서 최대입력 전류의 크기를 산정하기 위하여 해석적인 방법을 이용하여 산정하였다. 착자요크의 등가회로로부터 회로방정식을 도출하고 2차 미분방정식으로 표현하여 입력전류를 산정하였다. 산정된 입력전류는 회로해석 툴 및 유한요소해석을 이용한 상용소프트웨어와 비교하여 해석방법의 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.993-997
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• 1998

This paper presents a two-switch boost chopper with a sinewave current shaping and power factor correction scheme, which is applied for driving electronic ballast using high frequency resonant inverter. A working principle of the proposed one-converter type electronic ballast with power factor correction and active filtering schemes is described on the bases of the equivalent circuit of each operation mode, together with operation analysis. The steady-state performance evaluations of this electronic ballast are illustrated and discussed in experiment.

• Journal of Power Electronics
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• v.16 no.2
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• pp.399-413
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• 2016

This paper presents a topology for a modular power electronic transformer (PET) and a control scheme. The proposed PET consists of a cascaded H-Bridge rectifier on the primary side, a high-frequency DC/DC conversion cell in the center, and a cascaded H-Bridge inverter on the secondary side. It is practical to use PETs in power systems to reduce the cost, weight and size. A detailed analysis of the structure is carried out by using equivalent circuit. An algorithm to control the voltages of each capacitor and to maintain the power flow in the PET is established. The merits are analyzed and verified in theory, including the bi-directional power flow, variable voltage/frequency and high power factor on the primary side. The experimental results validated the propose structure and algorithm.