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인덕터의 DC 바이어스 특성을 고려한 대용량 DC-DC 컨버터의 손실계산
조영창(Young-Chang Jo),최주엽(Ju-Yeop Choi),정승기(Seung-Ki Jung),최익(Ick Choy),송승호(Seung-Ho Song) 대한전기학회 2011 전기학회논문지 Vol.60 No.4
It is necessary to accurately predict converter losses for optimized design of a high-power DC-DC converter. The losses of switching devices and inductor among the elements of the converter take significantly greater proportion. The current ripple will be determined by the size of the inductance and this inductance value varies depending on the DC amount of inductor current. As the inductance changes according to load current, the change influences not only the inductor loss itself but also the total converter loss. In this paper, for more accurate design of a bi-directional DC-DC converter for 30㎾-class energy storage system, more accurate computational model is proposed considering inductance variation according to the load current change. The inductance changes using variable magnetic cores are verified and converter efficiency is tested through simulations and experiments.
CMOS 아날로그 집적회로를 위한 새로운 구조의 One port 저항 셀
조영창,김성환,최평,Jo, Young-Chang,Kim, Sung-Hwan,Choi, Pyung 대한전자공학회 1996 전자공학회논문지-A Vol.33 No.3
It is difficult to fabricate precise resistors for the analog integrated circuits using MOS technology. Until now polysilicon resistors were used at the analog integrated circuits, but some deviations of resistance and sensitive variation processes still cause their misactions. In order to improve these misactions, we suggest a CMOS resistor cell which provides precise resistance and excellant linearity. Also we designed the second order active low pass filter using the CMOS resistor cells and verified their superior performances compared to the actual resistors.
멀티센서신호 인터페이스용 Custom IC 를 위한 CMOS 회로 설계
조영창,최평,손병기 ( Young Chang Jo,Pyung Choi,Byung Ki Sohn ) 한국센서학회 1994 센서학회지 Vol.3 No.1
In this paper, the multi-sensor signal processing IC is designed. It consists of an analog multiplexer far selection of multi-sensor signals, active filters for noise rejection and signal amplification, and a sample and hold circuit for interface : with digital signal processing. By implementing these circuits with CMQS transistors, integration, low power dissipation and miniaturization of the total signal processing system have been made possible.
모드절환을 고려한 양방향 DC-DC 컨버터의 디지털 전압 제어기 설계
조영창(Young-Chang Jo),임지훈(Ji-Hoon Lim),송승호(Seung-Ho Song),최주엽(Ju-Yeop Choi),이국선(Kook-Sun Lee),최익(Ick Choy),권태석(Tae-Suk Kwon),이상준(Sang-Joon Lee),이현동(Hyun-Dong Lee) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7
HEV(Hybrid Electrical Vehicle)의 배터리와 전동기/발전기용 인버터 사이에 전력의 흐름에 따라 바뀌어 동작하는 양방향 컨버터가 장착된다. 이 컨버터는 낮은 배터리의 전압을 승압해 DC-Link 전압을 높혀줌으로써 전동기의 전류용량을 낮춰 줄수 있으며 그에 따른 전동기의 부피를 감소시키고 손실을 줄이는 역할을 한다. 본 논문에서는 HEV에서 사용되는 양방향 컨버터의 모드 절환을 포함한 디지털 제어 방법을 소개하고, 시뮬레이션을 통해 검증하였다.
부하 전류 변화에 따른 인덕턴스 변동을 고려한 대용량 DC-DC 컨버터의 손실 계산
조영창(Young-Chang Jo),송승호(Seung-Ho Song),최주엽(Ju-Yeop Choi),최익(Ick Choy) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10
인덕터는 컨버터에 들어가는 중요한 수동소자 중 하나이다. 인덕턴스의 값에 따라 컨버터의 리플이 결정 되며, 리플은 곧 시스템의 효율과 연관되어 진다. 인덕터는 직류 전류가 상승함에 따라 인덕턴스가 감소하는 특징이 있으며, 이를 DC바이어스특성이라 한다. 본 논문에서는 이러한 인덕터의 DC바이어스특성을 고려한 컨버터의 손실 특성을 계산하고, Matlab을 이용해 시뮬레이션을 하도록 한다.
상어 연골 추출물의 홍반-혈관 확장형 주사 환자에서의 치료 효과
한태영 ( Tae Young Han ),김범준 ( Beom Joon Kim ),김명남 ( Myeung Nam Kim ),허창훈 ( Chang Hun Huh ),노낙경 ( Nark Kyoung Rho ),김수홍 ( Soo Hong Kim ),홍혁기 ( Hyuck Ki Hong ),최연식 ( Yeon Shik Choi ),조영창 ( Young Chang Jo 대한피부과학회 2007 대한피부과학회지 Vol.45 No.12
Background: Persistent facial telangiectasia, erythema and flushing are the major cosmetic problems in patients with rosacea. However various therapeutic treatments for rosacea papules and pustules are not effective in reducing telangiectasia and flushing reactions. Matrix-centered theory that dermal matrix degradation can cause telangiectasis, erythema and flushing, is one of the various theories of rosacea pathogenesis. Shark cartilage extracts are collagenase inhibitors and can inhibit dermal matrix degradation. Objective: The purpose of this study was to evaluate the clinical effects of shark catilage extracts (Venatrix(R)) for erythematotelangiectatic rosacea patients. Methods: Twenty three patients with erythematotelangiectatic rosacea applied shark cartilage extracts twice daily for up to 8 weeks. Efficacy was evaluated by erythema index using mexameter (MPA 5, CK, Germany) and clinical photography. Results: Erythema index decreased from 525.7±114 to 413.9±101.7 (mean reduction: 21.3%) (p<0.1) after 8 weeks treatment. 16 patients (69%) showed excellent or good results by clinical photography. Transient stinging sensation was the most common adverse effect and these symptoms improved after the first few days. There were no other significant side effects. Conclusion: Shark cartilage extracts may be an effective treatment for mild erythematotelangiectatic rosacea. (Korean J Dermatol 2007;45(12):1253∼1257)