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폴리머 기판상의 Al-doped ZnO 박막의 두께에 따른 특성 변화
김봉석,김응권,강현일,이규일,이태용,송준태,Kim, B.S.,Kim, E.K.,Kang, H.I.,Lee, K.I.,Lee, T.Y.,Song, J.T. 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.2
In this paper, we fabricated TCO (transparent conductive oxide) electrode on flexible substrate in order to study effects of electrical and optical properties according to Al-doped ZnO(AZO) film thickness. The thickness of film was from 100 nm to 500 nm and was controlled by changing deposition time. We used High Resolution X-ray Diffractometer (HR-XRD) to analyze crystal structure and UV-visible spectrophotometer to measure property of optical transmittance, respectively. The surface images are obtained by using ESEM (Environment Scanning Electron Microscopy). In this experiment, all the AZO films deposited on flexible substrate show high transmittance over 90% and especially in the films with 400 nm and 500 nm thickness, the resistivity ($4.5{\times}10^{-3}\;{\Omega}-cm$) and optical bandgap energy (3.61 eV) are superior to the other films. 본 논문에서는 AZO 박막 두께 변화에 따른 구조적, 전기적, 광학적 특성의 영향에 대하여 연구하기 위하여 폴리카보네이트(PC : polycarbonate) 기판 위에 DC 스퍼터링법으로 증착시간을 변화시켜 박막의 두께를 조절하였다. 박막의 두께는 100 nm에서 500 nm까지 100 nm단위로 실험하였으며, 제작된 AZO 박막의 비저항 특성은 four point probe system를 이용하여 측정하였고, 박막의 입자크기, 표면상태를 Environment Secondary Electron Microscopy (ESEM)으로 관찰하였다. 또한 AZO 박막의 결정상태를 조사하기 위하여 High Resolution X-Ray Diffractometer (HR-XRD)를 이용하였고 광학적 투과도는 UV-visible spectrophotometer를 이용하여 분석하였다. 실험 결과 모든 박막에서 90% 이상의 광투과도를 보였으며 400 nm과 500 nm 두께의 AZO 박막에서는 $4.5{\times}10^{-3}\;{\Omega}-cm$의 비저항과 3.61 eV의 광밴드갭 에너지를 보였다.
김봉석(B.S.Kim),권오석(O.S.Kwon),김종필(J.P.Kim),이영재(Y.J.Lee),고창조(C.J.Koh),권철홍(C.H.Kwon) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1994 No.11_1
This study investigates the combustion characteristics of methane-hydrogen-air premixture, in a constant volume combustion chamber. Primary factors of the combustion characteristics of methane-hydrogen-air premixture are the equivalence ratio and hydrogen supplement rate. In the case of φ = 1.1, maximum combustion pressure and heat release rate have peaks, and they increase as the initial pressure and hydrogen supplement rate increase. The total burning time is also the shortest at the φ = 1.1, it shorten by lowering the initial pressure and by increasing the hydrogen supplement rate. The maximum flame temperature is shown at the φ = 1.0, and increasing the initial pressure and hydrogen supplement rate, it increases. The concentration of NO reveals the highest value at the φ = 0.9, and it increases by increasing the initial pressure and hydrogen supplement rate. It is also found that the limit of lean inflammability of methane-hydrogen-air premixture is greatly widened by increasing the hydrogen supplement rate.<br/>
김봉석(B.S.Kim),권오석(O.S.Kwon),김종필(J.P.Kim),이영재(Y.J.Lee),권철홍(C.H.Kwon),고창조(C.J.Koh),류정인(J.I.Ryu) 한국자동차공학회 1992 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The combustion characteristics in prechamber type constant volume com-bustion chamber are experimentally investigated. It is concluded that the geometric configurations of passsge hole, especially passage hole diameter , passage hole angle, and depth of intake hole, are main facters swaying the characteristics of combustion in main chamber.<br/> <br/>
김봉석(B.S.Kim),권오석(O.S.Kwon),이영재(Y.J.Lee),고창조(C.J.Koh),김종필(J.P.Kim),권철홍(C.H.Kwon) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
This study was investigated the combustion characteristics of methane-hydrogen-air premixtures with various equivalence ratio, hydrogen supplement rate and initial pressure in a disk-shaped constant volume combustion chamber. The main results obtained from the study can be summarized as follow. The flame propagation processes in near stoichiometric mixture of methane-air are propagated with a spherical shape, but in excess rich or lean mixtures are propagated with a elliptical shape. And, they are changed an instable elliptical shape flame with very regular cells by increasing the hydrogen supplement rate. Also, flame is sluggishly propagated as increased initial pressure in combustion chamber. The combustion characteristics such as volume fraction burned and flame radius are increased by increasing the hydrogen supplement rate, especially at the combustion middle period, but they are slowly increased by increasing the initial pressure. Maximum flame propagation speed is acquired at equivalence ratio of 1.0 - 1.1, and increased by increasing the hydrogen supplement rate, but it is decreased by increasing the initial pressure.<br/>
[論文] 압축비 변경에 따른 CNG기관의 성능특성 연구
김봉석(B.S.Kim),이영재(Y.J.Lee),고창조(C.J.Koh) 한국자동차공학회 1991 오토저널 Vol.13 No.3
Natural gas is one of the most promising alternative fuels for automative vehicles, because it has lower exhaust emissions and better fuel economy characteristics than gasoline and can be used in conventional engines with a little modification. In the present study, a conventional gasoline engine was modified to a CNG dedicated engine, which can be operated with CNG<br/> (compressed natural gas) only, and a engine bench test was performed at various compression ratios. As a result, it was revealed that the prototype CNG engine can be operated with lower exhaust emissions, better fuel economy and better thermal efficiency, but with a slightly reduced brake horse power, compared to the conventional gasoline engine.
김봉석(B.S.Kim),권오석(O.S.Kown),김종필(J.P.Kim),이영재(Y.J.Lee),고창조(C.J.Koh),권철홍(C.H.Kwon),류정인(J.I.Ryu) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The results indicated that even the very lean mixture, which is normally not flammable in single chamber type. could be burned within a comparatively short time by using sub-chamber with stratified charge method. Initial time of pressure increase and total burning times were decreased and maximum combustion pressure was increased as the equivalence ratio of both sub and main chamber (Φs. Φm) approached unity. Specifically, initial time of pressure increase and total burning times were greatly affected rather by the equivalence ratio of sub-chamber than that of main chamber. The maximum combustion pressure was little affected if the total equivalence ratio lies in the same range.<br/>
김봉석(B.S.Kim),방효선(H.S.Pang),이영재(Y.J.Lee) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_1
This study investigates the combustion characteristics of 6 types of natural gas as alternative fuel for automotive vehicles in a CVCC. Primary experimental factors of the combustion characteristics are the equivalence ratio and compositions of the gaseous fuel. The main results obtained from the study can be summarized as follows. In the case of Gas A and Φ= 1.1, maximum combustion pressure and heat release rate have peaks, and they increase as the heating value increase. The total burning time is also the shortest at the Gas A and Φ= 1.1, it shorten by increasing the burning velocity. The maximum flame temperature is shown at the Gas A and Φ = 1.0, and increasing the heating value, it increases. The concentration of NOx reveals the highest value at the Gas A and Φ= 0.9, and it increases by increasing Wobbe Index and burning velocity.<br/>