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김학성(Hack-Seong Kim),박영국(Young-Kuk Park),오준용(Jun-Yong Oh),성기봉(Ki-Bong Sung) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
최근 수년동안 의료 X-선 방비의 고전압 발생용 전원장치는 고주파 인버터 형태로의 개발이 가속화되어 단시간 촬영의 고성능화와 장치의 소형화 그리고 고전압 리플의 저감에 따른 피폭량 감소가 실현되고 있다. 본 논문은 이에 따른 의료 진단용 X-선 발생 시스템에서 40kW(125kV, 800mA) 고주파 전원 발생장치 개발에 관한 것으로 고주파 고전압 인버터, 고주파 고전압 변압기를 포함한 고전압 발생 회로, X-선 관전압, 관전류 제어부, 시스템 구동부의 설계 개발에 대하여 기술하였고, 전체 구성된 시스템의 실험 파형에 따른 동작 특성을 제시하였다.
다수 및 소수캐리어 소자에 적용 가능한 영전압영전류 스위칭 컨버터
안희욱,김학성,Ahn Hee-Wook,Kim Hack-Sung 전력전자학회 2005 전력전자학회 논문지 Vol.10 No.5
제안된 회로는 하나의 보조스위치를 이용하여 주 스위치와 정류용 다이오드가 턴-온/턴-오프 시 동시에 영전압과 영전류 조건을 만족시킨다. 그리고 이 회로에 사용되는 주 스위치는 다수 캐리어 소자뿐만 아니라 소수 캐리어 반도체 소자까지 사용할 수 있는 장점을 가지고 모든 PWM 컨버터에 적용 가능하다. 그리고 제안된 보조 스위치와 공진회로가 주 전력 경로에 존재하지 않으므로 주 스위치와 다이오드에 더 이상의 전압/전류 스트레스가 없게 된다. 제안된 컨버터의 유효성을 이론적 분석과 실험을 통하여 입증하였다. The paper proposes a novel ZVZCS PWM converter. It enables the main switch to be turned on/off with both zero voltage and zero current, the auxiliary switch to be turned on/off with ZCS, the rectifier diode to be turned on/off with ZVS. Moreover, this proposed soft switching technique is suitable for not only minority carrier device but also majority carrier semiconductor device. Since auxiliary resonant circuit of the proposed boost converter is placed out of the main power path, therefore, there are no voltage and current stresses on the main switch and diode. The operation of the proposed boost converter is explained and analyzed theoretical and experimentally, from a prototype operating at 100KHz.
공진형 고주파 인버터에서의 공진주파수 추적을 위한 PLL 기법
안희욱(Hee-Wook Ahn),김학성(Hack-Sung Kim),김상희(Sang-Hee Kim) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
The PLL (Phase-Locked Loop) techniques are employed to make the switching frequency of a resonant inverter follow the resonant frequency which may vary due to the load variations during operation, The conventional design guide of PLL is not suitable in these case since the inverter characteristics are not considered, In this paper, the phase characteristics of a resonant inverter is analysed and added to the closed loop, And the design of PLL with digital phase detector is illustrated for the output frequency to track the resonant frequency of the inverter.
벽오동 Firmiana platanifolia의 성분연구(1)
김재완(Jae Wan Kim),김학성(Hack Sung Kim),정우태(Uh Tae Chung),박해자(Hae Ja Bark) 대한약학회 1969 약학회지 Vol.13 No.2,3
A colorless needle crystalline substance, m.p. 170~171oC. was obtained from the bark of Firmiana platanifolia in 4% yield. The acetylation derivative of this compound shows m.p. 163-164oC. Through pharmacological screening tests, it was found that the original substance has an augmented contractility for isolated frog muscle in doses of 2.5 X 10-4~1 X 10-3g/ml.
병렬 MOSFET 스위치를 이용한 ZCT PWM Boost Converter
김태우(Tea-Woo Kim),허도길(Do-Gil Hur),김학성(Hack-Sung Kim) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
A ZCT(Zero Current Transition) PWM(Pulse-width -Modulation) boost converter Using parallel MOSFET switch is proposed m this paper. The IGBT(main switch) of the proposed converter is always turned on with zero current switching and turned off with zero current/zero voltage switching The MOSFET(auxiliary switch) is also operates with soft switching condition<br/> In addtion to, the proposed converter eliminates the reverse recovery current of the freewheeling diode by adding the resonant inductor, Lr, in series with the main switch. Therefore, the turn on/turn off switching losses of switches are minimized and the conduction losses by using IGBT switch are reduced. In addition to, using parallel MOSFET switch overcomes the switching frequency limitation occurred by current tail<br/> As mentioned above, the characteristics are verified through experimental results.
Dual 컨버터로 동작하는 새로운 ZCS PWM Boost Converter
김태우(Tea-Woo Kim),진기호(Gi-Ho Chin),김학성(Hack-Sung Kim) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
A Novel Zero Current 5witcing(ZC5) Pulse Width Modulation(PWM) boost converter for reducing two rectifiers reverse recovery related losses is proposed<br/> The switches of the proposed converter are operating to work alternatively turn-on and turn-off with soft switching(ZV5, ZC5) condition. The reverse recovery related switching losses and EMI problems of the proposed converter eliminates the reverse recovery current of the freewheeling diode (D, D1) by adding the resonant inductor Lr, in series with the switch 52<br/> The voltage and current stresses of the components are similar to those in its conventional hard switching counterpats. As mentioned above, the characteristics are verified through experimental results.
김태우(Tea-Woo Kim),안희욱(Hee-Wook Ahn),김학성(Hack-sung Kim) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
This paper introduces a boost converter using ZVT-PWM method. The main switch of the proposed converter is always switched at zero voltage and soft switching of auxiliary switches as well. Therefore, the proposed converter is reduced the turn off switching losses of the auxiliary switch and resonant transition period, resonant transition energy by using additional active switch compared with conventional ZVT-PWM converter, As mentioned above, the characteristics are verified through experimental results