• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.502-504
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• 1994

This paper describes an induction heating system which is full-bridge parallels resonant inverter. This system consists of current-fed type inverter, and a parallels resonant circuit with a matching transformer. A parallels resonant scheme is employed, and operating range of the proposed circuit with operating frequency and load parameter is demonstrated from the result of steady state. Also, this equipments testing result introduces, good efficiency and reliability of the system. Finally, this paper experimental results are given.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.199-202
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• 2008

In this paper, we studied a accuracy for CT using elastic epoxy. According to industry development, the quality where also the electric material is various is demanded. Insulation material is widely used because epoxy is superior to electrical and mechanical property. Until now, the possibility where the crack will occur is high because epoxy used to electrical products had high hardness. If thermal expansion is different of two material, contraction of epoxy heavily transformed turns ratio of CT Elastic epoxy absorbed in expansion and contraction of substance material by temperature. So we could design more exacted CT We had elastic test of elastic epoxy and made CT using elastic epoxy. At the result, We obtained turns ratio of within 4% superior to existing CT.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.287-292
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• 2004

The increasing use of nonlinear loads has resulted in an increase in the harmonic content of the load current for power transformers. Transformers subject to harmonic currents have higher losses and need to be derated. This paper presents a simple method for determining the capability of transformers to supply harmonic load currents and shows that the application of capacitor banks with a series connected reactor and harmonic filters will geatly increase the capability of transformers. The EDSA program was used as a simulation tool for the carse study.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2061-2062
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• 2011

국내 원자력발전소에 설치되어 있는 고압케이블은 장기운전에 따라 열화진단 및 유지보수의 필요성이 증대되고 있다. 주기적 안전성 평가(Periodic Safety Review) 및 계속운전과 관련하여서도 고압케이블의 관리방안이 지속적으로 요구되고 있다. 본 논문에서는 원자력발전소에 설치되어 있는 13.8kV급 고압케이블의 건전성을 확인하기 위하여 원자력발전소 계획예방정비 중 열화진단을 수행한 결과를 소개하고 있다. 특히 미국 NRC(Nuclear Regulatory Commission)에서는 케이블 진단 기법 11가지를 권고하고 있는데 본 논문에서는 그 중 국내 원자력발전소에 적용이 가능한 최신 케이블 진단 기술인 HFCT(High Frequency Current Transformer)를 이용한 부분방전(Partial Discharge ; PD) 측정, VLF(Very Low Frequency) 장치를 이용한 $Tan{\delta}$ 측정 및 열화상카메라를 이용한 케이블 온도 측정을 사용하여 고압 케이블 진단을 실시하였고, 그 결과를 서술하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2067-2068
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• 2011

국내 원자력발전소에 설치되어 있는 고압케이블은 장기 운전에 따라 열화진단 및 유지보수의 필요성이 증대되고 있으며, 주기적 안전성 평가(Periodic Safety Review) 및 계속운전과 관련하여서도 고압케이블의 관리방안이 지속적으로 요구되고 있다. 본 논문에서는 원자력발전소에서 경년열화로 진단되어 철거된 케이블을 수거하여 VLF(Very Low Frequency) 장비를 사용하여 가압을 한 후 HFCT(High Frequency Current Transformer)를 이용한 부분방전(Partial Discharge ; PD) 측정을 수행하여 향후 원자력발전소 계획예방정비 시 케이블을 대상으로 Off-line 부분 방전 진단이 가능한지를 검토하였고, 그 결과를 기술하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2083-2084
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• 2011

본 논문에서는 유입식변압기에 대한 부분방전진단방법에 있어 초음파센서 및 HFCT(High Frequency Current Transducer)센서의 동시측정방법 이용하여 유입식변압기 내부에서 발생한 부분방전신호의 위치추적 및 현장잡음에서의 유효한 부분방전 위치추적을 위한 하이브리드 센서적용방법을 제안하고 국내외 부분방전진단시험을 통하여 제안한 진단방법을 이용한 부분방전위치추적에 대한 고장진단사례를 소개하고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.467-472
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• 2005

In this paper, design and control of the novel SEPIC-Flyback converter(SF converter) is developed as a possible converter for fuel cell system. This output characteristic of SF converter is similar to Buck-Boost converter in that it can step-up or step-down the voltage. With the small signal equivalent circuit modeling of SF converter, control-to-output transfer function is obtained. SF converter couples up the inductive type converter to capacitive type converter with one transformer, which has less ripple current than its respective one does. To verify the validity of the proposed converter, 500W, 100kHz converter is designed and tested. ZVS switching and active clamping are also tested in practice.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.199-202
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• 2004

CCFL(Cold Cathode Fluorescent Lamp) are used to backlight of LCD(Liquid Crystal Display). This paper presents analysis of half-bridge type resonant inverter of CCFL drive in order to stable characteristics, and fluorescent lamp operation frequency is higher than resonant frequency for safe operation. Besides, The Piezoelectric ceramic transformer (PZT) is electro-mechanical device that transfers electrical energy through a mechanical vibration. The modified equivalent circuit model of the PZT considering the operating current level is derived to design the CCFL. The validity of this study was confirmed from the simulation and experiential result.

• Journal of Power Electronics
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• v.9 no.6
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• pp.874-883
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• 2009

This paper deals with an integrated voltage and frequency (VF) controller for isolated asynchronous generators (IAG) driven by a constant power pico-hydro uncontrolled turbine feeding three-phase four-wire loads. The proposed VF controller is used to control the frequency and voltage of an IAG with load leveling. Such a VF controller is also known as an integrated electronic load controller (IELC) which is realized using an isolated star/polygon transformer with a voltage source converter (VSC) and a battery at its DC bus. The proposed generating system with a VFC is modeled and simulated in MATLAB along with Simulink and Simpower system (SPS) toolboxes. The simulated results are presented to demonstrate the performance of an isolated asynchronous generator feeding three-phase four-wire loads with neutral current compensation.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.963_964
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• 2009

This paper presents an output ripple reduction of Active-Clamp Forward Converter, which is mainly composed of interleaving two active-clamping forward converters. By interleaving, Output ripple is reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switching and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis of this ouput reduction of Active-Clamp Forward Converter is described.