• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.210-213
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• 1990

This paper presents the countermeasure to present the main transformer of distribution substation from deteriorating and failing due to repeated magnetic force of the transformer winding by ground fault current in 22.9kV multi grounded distribution system. The Winding strength to the short circuit current is designed to be endurable to the stress of over current. But this design is related to the manufactures. In this paper we examine the application of shunt reactor to the neutral point of the low side of the transformer to reduce fault current due to the fault in the distribution lines we have analysed the fault characteristics of the system and calculated the optimum ohmic values of the neutral reactor.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1924-1926
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• 1997

With the development of power electronics, many new energy storage systems such as the superconducting magnetic energy storage, the flywheel energy storage, and the capacitive energy storage, etc. are being intensively studied recently in order to replace battery in some special applications, Among these innovative energy storage systems, the flywheel system exhibits some unique features such as high power density, easy maintenance and longer lifetime. This paper introduces the novel flywheel energy storage system. Operation and features of the system are illustrated and verified on a 6kVA, 20kHz IPM based experimental circuit for O/A application. The Halbach Array Motor is selected of the design of the three phase motor/generator for the flywheel energy storage system.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.77-79
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• 1996

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are 7.2kV, 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted for the model interrupters using the simplified synthetic testing facility in KERI. The results show that the model interrupters have sufficient interrupting capability and the new design concept is prefer for good interrupting performance.

• Journal of Power Electronics
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• v.9 no.6
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• pp.835-844
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• 2009

In this paper a new buck-boost type DC-DC converter is presented. Its voltage gain is positive, all active elements operate under soft-switching condition independent of loading, magnetic isolation and self output short-circuit protection exist, and very fast dynamic operation is achievable by a simple bang-bang controller. This converter also exhibits appropriate PFC characteristics since its input current is inherently proportional to the source voltage. When the voltage source is off-line, it is sufficient to add an inductor after the rectifier, then near unity power factor is achievable. All essential guidelines to design the converter as a DC-DC and a PFC regulator are presented. Simulation and experimental results verify the developed theoretical analysis.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.645-648
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• 1992

In a capacitor-discharge impulse magnetizer, one of the magnetic application system, a magnet is magnetized by the discharging current of capacitors. The conventional design of the magnetizer has been based on many year's experience. The behaviour of flux in the magnetizer should be calculated in order to produce the desired magnets. The analysis of the flux distribution is quite difficult. This is because both the magnetizing current and the applied voltage to the magnetizer are unknown. This paper describes the development of computer model for a capacitor-discharge impulse magnetizer using SPICE. Also, the detailed distribution of the flux density in a magnet magnetized by the impulse magnetizer be analyed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.794-798
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• 2002

This paper deals with a moving coil type linear motor for fast access of the miniature ODD. This slim-line motor is composed of the mover supported by guide mechanism, the coil wound into it, and the yoke attached to the permanent magnet for stator. The driving force is generated by the PM of the stator and the current in the coils of the mover. Magnetic circuit analysis and Finite Element Method are applied to estimate the thrust force at air gap. In order to compare the force characteristics between two methods, various experiment results are applied to verify on a prototype. Also the flexible modes of the motor are predicted through the FEM and the structural components are modified to locate this on high frequency region.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.657-659
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• 2001

Prototype DSLPM (Double Side Linear Pulse Motor) has a complicated magnetic circuit to be composed of permanent magnetics and winding. During the fabricating of DSLPM, we found that upper airgap length may be a little different from lower airgap length because of fabrication tolerance and error. So, a little difference of both airgap length have a various effect on the characteristics of DSLPM. Therefore, in this paper, we analyzed the normal force and maximum static thrust force according to the difference of both airgap length on DSLPM with finite element method. Obtained results can be used for design of DSLPM with higher performance.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.757-759
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• 2001

전동기 전원 개폐를 주목적으로 하는 전자개폐기는 빈번하고 불규칙한 개폐동작에 의해 발생되는 Arc 에너지에 대해 전기적으로 내구성능을 확보하는 것이 중요하다. 또한, 전기적 내구 성능은 수명과 품질을 결정하는 요인으로서 선진업체에서는 내구성능을 향상시키려 연구개발 활동에 집중하고 있다. 이러한 전기적 내구 성능을 향상, 평가하기 위해서는 장기간에 걸친 시험 기간과 시험규격에서 요구하는 조건을 만족시키는 시험 회로와 설비구성이 필수적이다. 여기서는 전기적 내구 성능에 대한 이해와 시험규격을 통한 시험회로 설계 및 설비제작에 대해 설명하고 시험결과를 분석하고자 한다.

• 전기의세계
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• v.28 no.3
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• pp.65-71
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• 1979

This paper examines the reasonable winding arrangements of designing tapped winding capacitor motors to used in two voltage sources. The approach of this paper is based partly on a hybrid equivalent circuit of a single phase induction motor, together with an experimental method by sample machines. In results, the distribution of etra and main windings ia the stator is to be balanced in each magnetic pole and in order to have the same torque output characteristics for two different voltage sources, the extra/main winding ratio is to be adjusted. Experimental results obtaired with sample macines of about 1/8 hp output rating are used with analysis to predict the favorable winding conditions.

• 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.