非晶質 Silicon 薄膜의 製作 및 그 Doping 效果

최범식,김수길,고년규,황정남,정원모,이철주 연세대학교 자연과학연구소 1982 學術論文集 Vol.9 No.-

SiH_4 기체에 PH_3 및 B_2H_6 기체를 0.7% 체적비로 혼합하여 rf glow 방전법으로 n형 및 p형 a-Si:H 박막을 기판온도 120℃에서 제작하여, 광투과도 측정, 열처리에 따른 전기 전도도의 변화 등을 조사하여 이들의 doping 효과를 연구하였다. n형, p형 및 undoped a-Si:H 박막의 optical gap은 각각 1.73eV, 1.86eV 및 1.86eV로 doping이 많이 이루어질수록 줄어 들었다. 250℃에서 열처리한 시료들의 상온에서의 전도도는 각각 2×10^-2Ω^-1㎝^-1, 5×10^-8Ω^-1㎝^-1, 5×10^-7Ω^-1㎝^-1이었고, 활성화 에너지 ??E는 각각 0.16eV, 0.49eV 및 0.48eV이었다. 300℃에서 열처리한 결과, ??E는 줄어 들고 전도도는 증가하였다. 350℃ 및 450℃에서 열처리한 결과 dehydrogenation 효과로 인하여 n형과 p형은 서로 상반되는 결과를 보였다. 즉, n형 시료의 전도도는 감소하고 ??E는 증가하였지만, P형 시료의 전도도는 증가하고 ??E는 감소하였다. 저온 영역에서 구한 n형 시료의 전도도로부터 hopping 활성화 에너지를 구한 결과 0.085eV이었다. Thin n-type and p-type a-Si:H films were prepared by rf glow discharge decomposition of silane mixed with 7×10^-3 parts per volume of phospine or diborane. All specimens were deposited on glass substrates held at 120℃. In order to determine the doping effects the opital absorption and dc conductivity of these specimens were measured after annealing at various temperatures. The optical gap was 1.73eV in the case of the n-type specimens, 1.80eV for the p-type, and 1.86eV undoped. This showed that the gap width decreased as the doping increased. The room temperatuer conductivities of these specimens annealed at 250℃ were 2×10^-2Ω^-1㎝^-1, 5×10^-8Ω^-1㎝^-1, and 5×10^-7Ω^-1㎝^-1, respectively, and the activation energies, ??E, of these specimens were 0.16eV, 0.49eV, and 0.48eV, respectively. For specimens annealed at 300℃, ??E decreased and the conductivity increased. When these specimens were annealed at 350℃ and 450℃, dehydrogenation caused opposite effects on the n-type and p-type specimens; the conductivities of n-type specimens decreased and ??E increased, but the conductivities of p-type specimens increased and ??E decreased.From an investigation of the temperature dependence of the conductivity of the n-type specimen in the low temperature region, we determined that the hopping activation energy was 0.085eV.

유도초음파에 의한 비균질 적층의 접합층두께 평가

조윤호,함효식,최흥호 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.4

비균질 적층 구조물에서의 유도초음파 전파는 이론적 분산성에 기초하여 실험적으로 규명된다. 이는 입사각도와 주파수의 적절한 선택은 적층구조물에서의 유도초음파 발생에 중요하다는 것을 드러낸다. 이론적 분산성은 접착층 두께와 층 두께, 물성치에 크게 의존한다. 실험적으로 분산성의 변화를 관찰하므로 비균질 적층 구조물의 접착층 두께를 측정하는 것이 가능하였다. The guided wave propagation in inhomegeneous multi-layered structures is experimentally explored based on theoretical dispersion curves. It turns out that proper selection of incident angle and frequency is critical for guided wave generation in multi-layered structures. Theoretical dispersion curves greatly depend on adhesive zone thickness, layer thickness and material properties. It was possible to determine the adhesive zone thickness of an inhomogeneous multi-layered structure by monitoring experimentally the change of dispersion curves.

전자선 증착장치 및 ITO 박막의 제작과 그 특성에 관한 연구

김수길,최범식,우정주,고년규,황정남,정원모,이철주 연세대학교 자연과학연구소 1982 學術論文集 Vol.9 No.-

태양 전지의 제작시 투명 전극막으로 쓰이는 ITO 박막을 제조하기 위하여 cathode 접지 방식의 전자총을 가진 정전 편향 집속형의 전자선 증착 장치를 제작하였다. 가속전압이 0∼15kV, 필라멘트 전류가 0∼28A, 두 전극판 사이의 간격이 11mm, anode와 deflector 사이의 간격이 30mm인 최적 실험조건하에서 생성된 전자선 spot의 크기는 길이가 20mm 폭이 1mm였으며, 전자선의 출력은 약 400W였다. 이 전자선 증착 장치를 이용하여 1600℃까지의 증발 온도를 가진 도체와 절연체 등을 쉽게 증착시킬 수 있었으며, 만드어진 ITO 박막은 약 5000Å의 두께에서 10^-1∼10^-2Ω·㎝의 비저항과 95%의 광투과율을 갖는다. An electron beam evaporator with a cathode grounded type electron gun was designed and constructed in order to deposit ITO thin films for photovoltaic applications. The optimum condition was observed with electode spacing of 11mm, 30mm between anode and deflector, a cathode inner diameter of 3mm and an anode inner diameter of 5mm. As the accelerating voltage varies from 0 to 15kV and ghe filament current from 0 to 28 A, the minimum electron beam spot has a 20mm length, and 1mm width and the output power ranges from 0 to 400W under the above optimum conditions. We can deposit materials whose evaporation temperature is over 1600℃ using this evaporator. And as a result ITO thin film showed a low resistivity of 10^-1∼10^-2Ω·㎝ and the transmittance of 95%.

Glow Discharge 증착법에 의한 a-Si:H 박막의 Doping 효과 및 비정질 Si 태양전지 제작에 관한 연구

지일환,염덕선,최범식,김수길,고년규 연세대학교 자연과학연구소 1983 學術論文集 Vol.12 No.-

GDa-Si:H박막의 전기전도도 σ, 활성화에너지 ΔE, 광흡수계수 α 및 optical oprtical gap energy E_g(opt.)를 측정하여 전기적, 광학적 성질을 조사하였다. 또한 이들 박막의 광전기력 응용으로서 a-Si:H ITO/_(p-i-n)접합 태양전지를 제작하여 광전기력 현상을 관찰하였다. The electrical and optical properties of GD a-Si:H films have been investigated to obtain electric conductivity σ, activation energy ΔE, optical absorption coefficient α, and optical gap energy Eg(opt.). As a photovoltaic application of GD a-Si:H film, amorphous silicon ITO/p-i-n heteroface solar cells have been fabricated and the photovoltaic characteristics of the solar cells have be studied.

형질전환 담배 식물체에서 개똥쑥 Terpene Synthase의 발현

박성길,홍성현,최근원,이윤형,정인식 경희대학교 생명자원과학연구원 2002 硏究論文集 Vol.22 No.-

Expression of Artemisia annua terpene synthase in transgenic tobacco plants was examined. A full length cDNA encoding terpene synthase was cloned into pILTAB357 vector and transgenic tobacco plants were generated. The integration of this gene was analyzed by genomic DNA PCR and Southern blot analysis. The transcription of the terpene synthase gene in tobacco was confirmed by RT-PCR and northern blot analysis.

Landscape in Stereo

Choi Youn Sik 한국콘텐츠학회 2011 ICCC International Digital Design Invitation Exhib Vol.2011 No.5

Ratee Influence in Targe-Setting and Target Achievability: An Empirical Analysis of Objective Performance Measures

( Youn Sik Choi ) 한국회계학회 2014 회계학연구 Vol.39 No.2

Empirical research in performance-based compensation has been silent on the performance target, which generates important incentives whenever the subordinates can influence the target-setting process. Moreover, research overlooks the effect of simultaneous use of different types of participative target setting methods on the subordinates` strategic response. In the ratcheting literature, target performance is generally treated as a threshold performance level that triggers bonus compensation. This target performance provides the subordinates with a constructive incentive to exert at least the threshold level of effort. On the other hand, because better performance can result in a less attainable future target performance via target ratcheting, the subordinates can also have a destructive incentive not to give the best level of effort for maximal performance. Most prior studies have not ill uminate various destructive incentives of the subordinates in the target-setting process while assuming that the superior can discern the proper target performance easily and quickly. Practically, the superior has difficulty in identifying proper performance because output performance is affected not only by input resources (e.g. subordinates efforts) but also by market conditions and production functions that are complicated and/or obscure to the superior. In order to promote the accuracy of target performance, the superior try to engage the subordinates in the target-setting process. The superior is likely to seek for communication with the subordinates in circumstances that adversely affect the accuracy of discerning the proper target performance. Participative target setting, however, may not work as expected. The subordinates can also have another destructive incentive to derive more achievable target performance by exerting their influence through the target-setting process. This study investigates how the subordinates exert influence on targets through negotiations with the superior by focusing on the ratchet parameters. This study is built on the findings documented in Choi and Hwang (2012), which suggest that when the subordinates succeed (fail) in meeting target performance, the probability of achieving target performance in the following period decreases (increases) with how sensitively target performance ratchets in response to actual performance in the current period. I find that the slope of the ratchet principle is smaller (larger) when the subordinates beat (miss) targets as they exert greater influence in the target-setting process. This implies that the more difficult-to-achieve target performance are set when the subordinates have less influence on the target-setting process. I also find that the serial correlation of target achievability, documented in Indjejikian and Nanda (2002), is reinforced as the subordinates have more influence. My findings mention that, from a perspective of the level of targets, the participative target-setting may produce an adverse effect as the subordinates exercise more influence. As opposed to tight and challenging targets recommended by prior studies, targets set by an active interaction between the superior and the subordinates tend to be loose and achievable. The subordinates` strategic response to the ratcheting slope may be concrete evidence on the creation of slack documented in prior studies. However, I do not argue that the superior should stop involving the subordinates in the target-setting process. There are several purposes using the participative target-setting. Especially, it is important that participation can provide the subordinates with higher satisfaction and motivate them for better performance. Since the subordinates` true capabilities are unobservable, it is inevitable for the superior to depend on the subordinates` cooperation in target-setting. My findings suggest that, in order to successfully design or implement performance-evaluation system in terms of motivational purpose, the superior should understand how the subordinates try to decrease target-level through the target-setting process. In addition, the accounting profession is to develop sound performance-evaluation system that provides the superior with means to induce positive net benefit from the trade-off between motivational effect of performance-improvement and adverse effect of target-decrease, accompanied by the active participation of the subordinates.

MountainStill in Stereo_110

Choi, Youn Sik 한국콘텐츠학회 2012 ICCC International Digital Design Invitation Exhib Vol.8 No.1

RayScatter.May15.1470

Choi, Youn Sik 한국콘텐츠학회 2015 ICCC International Digital Design Invitation Exhib Vol.2015 No.7

The mycelial growth of Agaricus bisporus to develop Thermo-tolerance variety

Youn-Lee Oh,Kab-Yeul Jang,Youn-Keol Nam,Young-Bok Yoo,Pyung-Gyun Shin,Won-Sik Kong,In-Gul Choi 한국버섯학회 2014 버섯 Vol.18 No.2

The white button mushroom, Agaricus biporus is commercially the fifth important edible mushroom, accounting for a Korean production of 10,996 tons in Korea, 2012. The button mushroom, A. bisporus, mostly cultivated at mushroom farm controlled 16-19°C temperature during fruiting period in all seasons. For this reason, the production costs including the cost of energy, is very expensive to keep optimal culturing temperature. In this study, mycelial growth of strains collected from various countries was investigated at different cultivation temperature conditions to use baseline data for developing thermo-tolerance varieties. Mycelial growth was recorded strains cultivated in CDA (Compost Dextrose Agar) after two weeks. 12 strains among total 264 strains were cultivated well in high temperature. These strains will be cultivated in high temperature to confirm relationships between mycelial growth and fruit-body formation in same conditions.