• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.164-166
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• 2004

In Recent, it became necessary to develope the technology about electrodeless fluorescent lamp according to demand of the electodeless fluorescent lamp system that used higher efficiency and advantage of long-lifetime. Especially, in the electordeless fluorescent lamp which used H-mode, efficiency of lamp is decided from matching parameter of antena and inverter, so it is of the utmost importance to design antena and inverter. Therefore, this paper used a transformer principle for an efficiency rising of electrodeless fluorescent lamp and interpreted an equivalent circuit, and confirmed a luminance characteristic by ferrite change of antenna and change of coil turns. Also, this paper used the thermoelectric element which can let you cool ferrite and antenna and confirmed the luminance characteristic along a change of ferrite and an antenna temperature.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1762-1764
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• 2003

변압기의 이상 징후를 조기에 검출하여 사고를 미연에 방지하기 위해 설치된 예방진단시스템은 현재 국내 9개 변전소에서 운영되고 있다. 이러한 예방진단시스템의 적극적인 활용을 위해서는 시스템을 구성하는 각 요소에 대한 신뢰성 검증과 주기적인 점검, 축적된 데이터의 분석을 통한 사고예방 검출 사례의 축적이 요구되고 있다. 변압기 예방진단시스템의 가장 중요한 항목인 유중가스 측정기는 변압기 드레인 밸브에 설치됨에 따라, 변압기 내부 절연유가 유중가스 측정기로 유동되는지에 대한 의문이 존재하여 왔다. 본 논문에서는 유동해석 프로그램인 Fluent 5.3과 Gambit 프로그램을 이용하여, 변압기 내부의 열에 의한 대류현상에 의해 순환하는 절연유가 좁은 파이프를 통하여 유중가스 측정기의 삼투막까지 도달하는 유동현상을 해석하였다. 유동해석 결과 절연유가 삼투막과 만나는 지점에서도 절연유의 유동에 의한 순환이 발생하여, 용존가스의 검출이 가능함을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1978-1980
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• 2003

본 논문에서는 광을 이용한 전류 측정 장치의 연구 내용에 대하여 기술하였다. 광을 이용한 전류 측정 장치의 가장 큰 문제점은 감도 저하를 주는 선형 복굴절 양이며, 이러한 선형 복굴절을 줄이는 방법은 광섬유를 비틀어서 선형 복굴절 양에 비해 원형 복굴절의 양을 크게 해주는 방법을 사용하였다. 광섬유를 비틀어서 측정한 결과는 측정 감도가 약 3배의 증가를 보였으며, 측정오차의 경우도 1 % 이내의 선형성을 나타내었다. 본 실험의 결과로 광섬유를 비트는 방법이 광을 이용한 전류 측정 장치의 선형 복굴절을 크게 감소시킴을 알 수 있었으며, 대전류 측정에 측정도를 높일 수 있다고 판단된다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1659-1665
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• 2015

In general, AT(Auto-transformer) is used to improve voltage sag and inductive interference in power lines and communication lines in AC electrical railway feeding system. Especially, Korean AT feeding system has different composition compared to other countries like Japan or France, so that it has some special characteristics. However, relays imported from other countries have been used in Korea, and settings of these relays should be modified and reflect distinct characteristics of Korean AT feeding system. Therefore, study about fault analysis based on modeled AT feeding system is important. In this paper, we modeled a single track AT feeding system by using PSCAD and analyzed fault current flow in case of trolley-rail short circuit fault. Finally, we presented current magnitude of each branch expressed by boosting current of AT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1590-1597
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• 1993

Power conversion system generally requires bidirectional converter. A storage energy of reactor is suppressed by regeneration of surplus electic energy in converter to power source. When an electric isolation in the power conversion system is required. the most suitable position for the isolation is the DC-Link part. A transformer in the DC part is minimized because of high repetition frequency. This paper proposes that power conversion system becomes bidirectional DC-DC converter with electric isolation by intergrated voltage control method. It is intergrated voltage control that makes system construciton simple, has control errow little quantity ans gets output response Quick. And the power-switches which should be operated is selected automatically without a detection of the current-direction.

• Journal of Power Electronics
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• v.6 no.2
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• pp.131-138
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• 2006

An active clamp ZVS PWM forward converter using a secondary synchronous switch control is proposed in this paper. The proposed converter is suitable for low-voltage and high-current applications. The structure of the proposed converter is the same as a conventional active clamp forward converter. However, since it controls the secondary synchronous switch to build up the primary current during a very short period of time, the ZVS operation is easily achieved without any additional conduction losses of magnetizing current in the transformer and clamp circuit. Furthermore, there are no additional circuits required for the ZVS operation of power switches. Therefore, the proposed converter can achieve high efficiency with low EMI noise, resulting from soft switching without any additional conduction losses, and shows high power dens~ty, a result of high efficiency, and requires no additional components. The operational principle and design example are presented. Experimental results demonstrate that the proposed converter can achieve an excellent ZVS performance throughout all load conditions and demonstrates significant improvement in efficiency for the 100W (5V, 20A) prototype converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.371-377
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• 2006

Cold cathode fluorescent lamps (CCFL) show complex characteristics, which make it difficult to drive them in parallel. In this paper, a multi-lamp driving scheme is proposed to drive multiple lamps for LCD back light to reduce output current unbalance. This propose system is composed of parallel CCFLs, series transformers. The driving system adopts only one backlight inverter to drive multi cold cathode fluorescent lamps (CCFL). Moreover the circuit introduces a multi-lamp driving transformer to reduce lamp-current imbalance. The validity of the proposed scheme is confirmed by the simulated and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.520-528
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• 2006

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the phase-shift switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.642-643
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• 2007

본 논문은 우리 전력연구원에서 보유하고 있는 실시간 시뮬레이터(RTDS)를 이용하여 산학연을 대상으로 하여 개발된 교육, 훈련 시스템 중 하나의 아이템인 변압기 과도현상 훈련코스데 대해 소개하고자 한다. 실계통 현장에서 자주 발생하는 변압기 내부고장을 RTDS/RSCAD 상에서 구현하여 변압기 과도특성을 파악한 후 계통해석에 이용하고, 변압기 돌입전류 현상과 포화현상 모의를 통하여 변압기 과도현상에 대해 명확히 이해할 수 있도록 하는데 본 훈련코스의 목적이 있다. 우리 전력연구원은 2002년부터 산학연을 대상으로 실시간 시뮬레이터 응용 계통해석 교육을 여러차례 시행해 오고 있으며, 2007년 3월 교육, 훈련 시스템 구축이 완료됨에 따라 앞르로 정기적인 교육을 시행할 예정이다.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.677-681
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• 2014

A high voltage pulse generator was fabricated to radiate ultrawide band electromagnetic pulse. A coaxial type of Blumlein pulse forming line is employed to produce a pulse of high voltage (>300 kV) and short pulse duration (~5 ns). A helical strip/wire type of air-cored pulse transformer was used to charge the Blumlein pulse forming line up to more than 300 kV. A peaking switch is essential to make the pulse rise time as fast as possible. Typically, the rise time is ~500 ps. The output pulse of the generator is radiated into air through an exponentially tapered TEM horn antenna. The electric field intensity of a radiated pulse was measured as a function of the distance from the transmitting horn as well as the output voltage of the peaking switch. The peak-to-peak value of the electric field intensity at 10 m from the TEM antenna was~100 kV/m.