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김환동,최길호,윤도영,Kim, Hwan-Dong,Choi, Kil-Ho,Yoon, Do-Young 한국반도체디스플레이기술학회 2008 반도체디스플레이기술학회지 Vol.7 No.4
Thin film has been an increasing important subject of intensive research, owing to the fact that these films possess desirable optical, electrical and electrochemical properties for uses in many semi-conducting nano-crystal applications, such as light-emitting diodes, lasers and solar cell applications. Here, ZnSe thin films were deposited by electrochemical method for the applications of light emitting diode. Electrochemical deposition of ZnSe thin film is not easy, because of the high difference of reduction potential between zinc ion and selenium acid. In order to handle the band gap of ZnSe crystal thin films easily, electrochemical methods are promising to manufacture these films economically. Therefore we have investigated the present study to characterize zinc selenide thin films deposited on ITO glass plates electrochemically. The luminescent properties of ZnSe films have been evaluated by UV-Vis spectrometer and luminescence spectrometer. And the morphology of the film surface has been discussed qualitatively from SEM images.
플라스틱 솔더볼의 열응력 해석을 통한 최적 솔더볼 설계 기술
김환동(H.-D. Kim),윤도영(D.-Y. Yoon),황진우(J.-W. Hwang) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
Recently, Pb-free solder ball technology, which is getting more significant in miniaturization of electronic equipment, and resolution of recent environmental problems, is necessary to be developed. A plastic-core solder ball is much promising in those considerations. Plastic-core solder balls have the tendency to replace the usual metal-core solder ball from low material cost and superior mechanical properties. The thermal effects, however, are important in manufacturing process, such as deposing nano-sized metal thin film on the spherical polymer surface. Furthermore plastic-core solder balls are easy to be broken due to CTE and elastic coefficient of material property from heat transfer. We propose technical computational investigations for the manufacturing design and the reliability of plastic-core solder ball from thermal stress analysis.
Zinc Blende 구조를 가지는 ZnSe 결정의 밴드 특성에 관한 연구
박정민,김환동,윤도영,Park, Jeong-Min,Kim, Hwan-Dong,Yoon, Do-Young 한국전기화학회 2011 한국전기화학회지 Vol.14 No.3
ZnSe는 가시광선 영역에서 넓은 밴드갭을 가지고 있는 II-VI족 화합물 반도체 소자로서 레이저 다이오드, 디스플레이 그리고 태양전지와 같은 다양한 응용분야에 적용되고 있다. 본 연구에서는 전기화학적 전착방법을 이용하여 ITO 전극상에 ZnSe 박막을 합성하여, XRD와 SEM으로 ZnSe 결정의 합성과 zinc blende 구조의 형태를 관측하였고, UV 분광기를 활용하여 밴드갭을 측정한 결과 2.76 eV이었다. 또한, 분자동역학에서 활용되는 밀도범함수 이론 (DFT, Density Functional Theory)을 도입하여 ZnSe 결정에 대한 밴드 구조의 해석을 수행하였다. Zinc blende구조를 갖는 ZnSe 결정에 대하여 LDA (Local Density Approximation), PBE (Perdew Burke Ernzerhof), 그리고 B3LYP (Becke, 3-parameter, Lee-Yang-Parr) 범함수를 이용하여 밴드구조와 상태밀도 (Density of State)를 모사하였다. 각각의 경우에 대해 에너지 밴드갭을 구한 결과, B3LYP 범함수로 해석한 경우에 실험치와 근사치인 2.65 eV의 밴드갭을 보여주었다. ZnSe, as a II-VI compound semiconductor which has a wide band gap in the visible region is applicable to the various fields such as laser diode, display and solar cell. By using the electrochemical deposition method, ZnSe thin film was synthesized on the ITO glass substrate. The synthesis of ZnSe grains and their structure having zinc blende shape were verified through the analysis of XRD and SEM. UV spectrophotometric method determined the band gap as the value of 2.76 eV. Applying the DFT (Density Functional Theory) in the molecular dynamics, the band structure of ZnSe grains was analyzed. For ZnSe grains with zinc blende structure, the band structure and its density of state were simulated using LDA (Local Density Approximation), PBE (Perdew Burke Ernzerhof), and B3LYP (Becke, 3-parameter, Lee-Yang-Parr) functionals. Among the calculations of energy band gap upon each functional, the simulated one of 2.65 eV based on the B3LYP functional was mostly near by the experimental measurement.
이승복,김준태,이지원,김경환,김나진,김지민,김산,김환동,황민우,송예진,김진영,배귀남 한국대기환경학회 2023 한국대기환경학회지 Vol.39 No.5
The smog chamber is a research facility that simulates atmospheric phenomena such as secondary pollution of ozone and aerosols under different atmospheric conditions. It enables the investigation of photochemical reaction processes, yields, and products, as well as physicochemical properties of secondary aerosol. Since the beginning of smog chamber research under the 1950s, experiments mainly on ozone and particle formation have been conducted, depending on the chamber specification and research trends. Smog chamber research in Korea began in the early 2000s and has continued since 2010 due to growing interest in particulate matter pollution. This study covers the domestic and global history of smog chamber research, as well as significant recent research advancements, which provides recommendations for future studies in smog chamber research.