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제어 방식에 따른 20 W급 LED Converter 설계 및 분석
정영기,김성현,박대희,Jeong, Young-Gi,Kim, Sung-Hyun,Park, Dae-Hee 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.1
In this paper, by designing 20 W class driving circuit for driving high-power LED (Light Emitting Diode), we are going to comparatively carry out the analysis of characteristics for power circuit according to each design method. In this case, 200 V 60 Hz was performed as input data. The electrical characteristics such as voltage, current and ripple are checked for constant current circuit and constant voltage circuit in the LED module. In addition, as the ripple has an influence on illumination of LED light, low temperature working (-20 [$^{\circ}C$]) and high temperature working(80 [$^{\circ}C$]) are measured to make sure the ripple characteristics in accordance with temperature. In low temperature operation -20 [$^{\circ}C$] measurements, both constant current circuit and constant-voltage circuit were less impacted on input fluctuation, whereas in the high temperature operation 80 [$^{\circ}C$], current voltage in constant voltage circuit was surge after 430 [hour]. Voltage current ripple of constant current circuit was much less than constant voltage circuit, therefore we can show that constant current circuit is more stable.
고출력 LED를 구동하기 위한 정전류 부스트 컨버터 회로 설계
정영기(Young Gi Jeong),김남군(Nam Goon Kim),양종경(Jong Kyung Yang),박대희(Dae Hee Park) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
최근 에너지 절약에 대한 관심이 고조되면서 기존 광원보다 효율이 좋은 광원개발이 계속되고 있으며 그 대표적인 것이 고효율 및 고출력(high-power) LED이다. 고출력 LED의 개발로 인해 일부에서는 일반 조명용으로 사용하려는 연구가 진행 중 이다. LED를 조명용으로 사용하기 위해서는 구동회로, 광학설계, 방열설계 등을 포함한 조명시스템의 구성이 필요하다. 이 중 구동회로는 사용용도와 LED 구동특성 등에 따라 구동회로를 구성하여야 하며 이러한 구동회로 기술에는 벅, 부스트, 벅-부스트 컨버터 방식이 있다. 본 논문에서는 정전류 구동회로를 사용함에 있어 부스트 방식을 사용한 컨버터를 통해 7EA의 LED를 안정적으로 구동하고자 설계하였다. 이때 구동전류는 500 [㎃]로 설정하였으며 이에 따라 입력전압에 대한 전기적 특성을 측정한 결과 7 [V]이상일 때부터 전류특성이 안정화 되는 특성을 확인할 수 있었다.
정영기(Young Gi Jeong),조금남(Keum Nam Cho) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Air pre-heater using waste heat generated from high temperature generator plays a role of enhancing the COP of the absorption system. Heat pipe heat exchanger (HPHX) was applied for the pre-heater. It was recommended the complete geometrical descriptions which were about tube arrangement, tube diameter and fin outside diameter et al. by Kays and London. But it has the differences about fin outside diameter and transverse, longitudinal tube spacing et al. So this research were studied to find a j-factor against Reynolds number to predict the temperature through the finned tube banks at outlet respectively. The dimensions of heat pipe were 21.7㎜ in O.D, 16.4㎜ in I.D, and 1003mm in length. The circular fins had tip diameter of 45.5㎜. The HPHX had 6 rows that each row has 7, 6 pipes respectively, had with staggered arrangement.
방전관 형태 및 열화 조건에 따른 세라믹 메탈할라이드 램프의 흑화원인 분석
김우영(Woo-young Kim),이세일(Se-il Lee),양종경(Jong-kyung Yang),정영기(Young-gi Jeong),박대희(Dae-hee Park) 대한전기학회 2010 전기학회논문지 Vol.59 No.12
In order to analyze the reason of wall blackening, which affect the decline of lifetime in a ceramic metal halide lamp, we carried out the deterioration of ceramic tubes by a change in operating conditions with arc tubes of two types of spherical and cylindrical, and we have confirmed the cause of wall blackening through the analysis of element composition and spectrum from SEM/EDS and spectrum analyzer. Wall blackening of tungsten was shown by sputtering from ignition in 20 minute on/off condition and wall blackening from chemical reaction between PCA wall and rare earth halides was shown significantly in a condition without on/off test. Especially, the wall blackening and the decline of luminous flux were reduced by inner convection in spherical type arc tube. Moreover, the color temperature and color coordinate were changed by reduction of emission spectrum of Dy which causes the chemical reaction with PCA wall.
A549 인체폐암세포의 증식에 미치는 신령버섯 추출물의 영향에 관한 연구
최우영(Woo Young Choi),박철(Cheol Park),이재윤(Jae-Yun Lee),김기영(Gi-Young Kim),박영민(Yeong Min Park),정영기(Yong-Kee Jeong),이원호(Won Ho Lee),최영현(Yung Hyun Choi) 한국식품영양과학회 2004 한국식품영양과학회지 Vol.33 No.8
브라질 기원인 신령버섯(A. blazei murill)은 강력한 항암 및 면역강화 작용을 가진 것으로 알려져 있다. 본 연구에서는 신령버섯 수용성 추출물(water extracted A. blazei Murill, WEAB)이 A549 인체 폐암세포 증식에 미치는 영향을 조사하였으며, 증식억제와 연관된 기전 해석을 시도하였다. WEAB가 처리된 A549 세포는 처리 농도 의존적으로 생존율이 감소되었으며, WEAB 처리는 암세포의 다양한 형태적 변형을 유발하였다. Flow cytometry 분석 결과로서 WEAB 처리에 의한 A549 폐암세포의 증식억제는 세포주기 G2/M arrest 및 apoptosis 유발과 직접적으로 연관성이 있음을 알 수 있었다. WEAB가 처리된 암세포에서 전사 및 번역 수준에서 cyclin A 발현의 감소 및 Cdk inhibitor p21 발현의 증가 현상이 관찰되었으나, cyclin B1, Cdk2, Cdc2, Wee1, Cdc25C 및 p53 등의 발현에는 큰 변화가 관찰되지 못하였다. 또한 WEAB의 처리는 COX-2 선택적 발현 저하를 유발하였으나, telomere 조절 관련 유전자들의 발현에는 큰 영향을 주지 못하였다. 이상의 결과는 신령버섯 추출물이 강력한 항암 및 암예방 효능의 잠재력을 가지고 있음을 의미하며, 이에 관한 지속적인 연구가 필요할 것으로 생각된다. Agaricus blazei Murill is a medicinal mushroom native to Brazil. It used to be a source of antitumor and immunoactive compounds and considered a health food in many countries. In the present study, it was examined the effects of water extract of A. blazei (WEAB) on the growth of human lung carcinoma cell line A549 in order to investigate the anti-proliferative mechanism by WEAB. Treatment of A549 cells to WEAB resulted in the growth inhibition, morphological change and induction of apoptotic cell death in a dose-dependent manner as measured by MTT assay and flow cytometric analysis. Flow cytometric analysis revealed that WEAB caused G2/M phase arrest of the cell cycle, which was associated with a down-regulation of cyclin A in both transcriptional and translational levels. WEAB treatment induced a marked up-regulation of cyclin-dependent kinase (Cdk) inhibitor p21, however, the levels of Cdk2, Cdc2, Wee1, Cdc25C and p53 expression were remained unchanged in WEAB treated cells. In addition, WEAB treatment inhibited the levels of cyclooxygenase (COX)-2 mRNA and protein without alteration of COX-1 expression. Taken together, these findings suggest that WEAB may be a potential chemotherapeutic agent for the control of human lung carcinorma cells and further studies will be needed to identify the active compounds that confer the anti-cancer activity of WEAB. Once such compounds are identified, the mechanisms by which they exert their effects can begin to be characterized.
단일 패키지의 특성 분석을 통한 고출력 발광 다이오드 모듈의 접합 온도 측정
이세일,김우영,정영기,양종경,박대희,Lee, Se-IL,Kim, Woo-Young,Jeong, Young-Gi,Yang, Jong-Kyung,Park, Dae-Hee 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.12
The temperature of junction in LED affects the life time and performance. however, the measurement of junction temperature in module is very difficult. In this paper, to measure the junction temperature in LED module, optical and electrical properties is measured in single package in temperature from 25 [$^{\circ}C$] to 85 [$^{\circ}C$], and then junction temperature can is estimated in module with measuring the average voltage of single package. As results, the junction temperature of single package is measured the temperature of 61.2 [$^{\circ}C$] in ambient temperature, also, the junction temperature of LED module is measured the temperature of 72.5 [$^{\circ}C$] in ambient temperature.