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열 CVD법에 의한 GaN nanowire 합성

  • 이철진;류승철;이태재;서승환;이확주;류현
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2001년도 제21회 학술발표회 초록집
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    • pp.42-42
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    • 2001
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화학적 기상 증착법으로 제작된 얇은 이황화 몰리브덴 박막의 전자구조

  • 서성원;문지훈;강상우;김정원
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.126.2-126.2
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    • 2015
  • 대표적인 금속 칼코지나이드 2차원 물질인 이황화 몰리브덴($MoS_2$)의 대면적 합성을 위해 화학적 기상 증착 (Chemical Vapor Deposition) 방법을 이용하였다. 몰리브덴을 포함한 $Mo(CO)_6$ 전구체와 황이 포함된 $H_2S$ 가스를 적절한 비율로 반응시켰고, 증착 속도를 조절하여 한 층부터 다섯 층까지의 얇은 $MoS_2$ 박막을 제작할 수 있었다. $MoS_2$ 박막들이 층별로 균일 하게 증착 되었는지 확인하기 위해 라만 분광법을 이용 하였고, x-선 분광법을 통해 몰리브덴과 황의 정확한 정량비를 알 수 있었다. 뿐만 아니라, 우리는 두께 의존성을 갖는 이차원 물질인 $MoS_2$ 각 층마다 나타나는 전자 구조적 특성 분석을 위해 자외선 분광법, 역광전자 분광법, 전자 에너지 손실 분광법을 사용하였다. 그 결과, $MoS_2$ 박막의 두께 별 일함수, 가전자대 최대값, 전도대 최소값, 밴드갭의 변화를 관찰할 수 있었다. 이는 기존 계산 결과와 비교하여 잘 일치함을 알 수 있다.

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변위 각도 동시 측정용 복합 레이저 간섭계의 제작과 특성 분석 (Development and performance test of a complex laser interferometer for simultaneously measuring displacement and 2-D angles)

  • 김재완;김종안;강주식;엄태봉
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 춘계학술대회 논문집
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    • pp.573-576
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    • 2005
  • A compact linear and angular displacement measurement device was developed by combining a Michelson interferometer and an autocollimator to characterize the movement of a precision stage. A Michelson interferometer and an autocollimator are typical devices for measuring linear and angular displacement, respectively. By controlling the polarization of reflected beam from the target mirror of the interferometer, some part of light was retro-reflected to the light source and the reflected beam was used for angle measurement. The interferometer and the autocollimator use the same optic axis and the target mirror can be easily and precisely aligned orthogonal to the optic axis by monitoring the autocollimator s signal. The autocollimator was designed for angular resolution of 0.1 arcsec and dynamic range of 60 arcsec. The nonlinearity error of interferometer was minimized by trimming the gain and offset of the photodiode signals. Through the experiments, we evaluate the performance of measurement device and discuss its applications.

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Effect of pH on the Size Distribution of Au Nanoparticles

  • Kang, Ae-Yeon;Park, Dae-Keun;Lee, Cho-Yeon;Yun, Wan-Soo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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    • pp.390-390
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    • 2011
  • The size distribution of gold nanoparticles (NPs) is an important factor in their application to various fields of nanotechnology such as nanodevice fabrication, nanobio measurements, medical diagnosis, and so on, since the properties of nanoparticles depend on the size. As the pH of the reaction mixture was increased, the size distribution of gold NPs synthesized via sodium citrate reduction method was getting narrower and it finally became quite mono-dispersive when the pH was higher than ca. 7. 0.1M NaOH solution was used in controlling the pH, while the ratio between sodium citrate and HAuCl4 was fixed to 3:1 whose initial pH was about 5. Scanning and tunneling electron microscopy and UV/Vis spectrometry were used to characterize the resulting Au NPs. The change of the size distribution of the NPs was discussed with the change of the reaction rate related to the change of hydroxyl ion concentration.

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Pt/Pd 열전대의 실온보상을 위한 Cu-Ni 합금 개발 (Development of Cu-Ni Binary Alloys for Room Temperature Compensation of Pt/Pd Thermocouple)

  • 김용규;강기훈;감기술;이영희
    • 센서학회지
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    • 제13권6호
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    • pp.405-410
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    • 2004
  • Compensation wires for Pt/Pd thermocouple was manufactured using Cu/Ni alloys. Their thermoelectric voltage has been tested from room temperature to about $150^{\circ}C$. Alloys of $Cu_{95.5}Ni_{4.5}$ and $Cu_{89.5}Ni_{10.5}$ introduced only small emf differences to Pt/Pd thermocouples, indicating a real possibility of industrial use. Above $1000^{\circ}C$, the temperature difference was expected to he small as ${\pm}0.5^{\circ}C$, and the difference would be minimized by adjusting the Ni content with a small amount.