• Progress in Superconductivity
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• 제6권2호
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• pp.108-112
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• 2005

We investigated temperature behavior of superconducting fault current limiters (SFCLs) during quenches. Knowledge on temperature behavior during quenches is important to the design of SFCLs, because the temperature of SFCLs is related to their stability. SFCLs were fabricated by patterning $Au/YBa_2Cu_3O_7$ thin films grown on sapphire substrates into meander lines by photolithography. A gold film grown on the back side of the substrate was patterned into a meander line, and used as a temperature sensor. The front meander line was subjected to simulated AC fault currents, and the back line to DC current. They were immersed in liquid nitrogen during the experiment for effective cooling. Overall, temperature at the back side of SFCLs was close to that at the front side. It was closer at the beginning of faults, and at lower applied voltages. Temperature distribution at the back side was even except at the edge, as at the front side. These results tell that the whole SFCL was heated to similar degree during quenches, and that effective cooling of SFCLs at the back side is as important to the stability of SFCLs as at the front side. The results could be explained with the concept of heat transfer within the film.

• 센서학회지
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• 제16권6호
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• pp.395-400
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• 2007

Ambient drying sol-gel processing was used for monolithic silica ambigels in the temperature range of $130-250^{\circ}C$. A new method of mesopore ambigels, which mean the aerogels prepared by ambient pressure drying process synthesis, is suggested at first. This method includes two important approaches. The first point is that $SiO_{2}$ surface modification of wet gel was performed by trimethylchlorosilane in n-butanol solution. This procedure is provided the silica gel mesopore structure formation. The second point is a creation of the ternary azeotropic mixture water/n-butanol/octane as porous liquid, which is effectively provided removing of water such a low temperature by 2 step drying condition under ambient pressure. The silica aerogels, which were prepared by ambient pressure drying from azeotropic mixture of water/n-butanol/octane, are transparent, crack-free and mesoporous (pore size ${\sim}$ 5.6 nm) with surface area of ${\sim}$ $923{\;}m^2/g$, bulk density of $0.4{\;}g/cm^3$ and porosity of 85 %.

• 센서학회지
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• 제7권2호
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• pp.97-102
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• 1998

PPV(poly(p-phenylenevinylene))를 발광체로 이용한 유기 박막 EL 소자를 다양한 구조와 조건으로 제작하였으며, 그 전기-광학적 특성을 평가하였다. 제작된 EL 소자는 단층구조(ITO(indium tin oxide)PPV/Mg), 이층구조 (ITO/PVK(poly(N-vinylcarbazole))/PPV)Mg와 ITO/PPV/Polymer matrix+PBD/Mg) 그리고 삼층구조 (ITO/PVK/PPV/PS(polystyrene)+PBD(butyl-2-(4-biphenyl)-5-(4-tert-butylphenyl-1,3,4-oxadiazole))/Mg)를 가지며, 그들의 전기광학적 특성을 상호 비교하였다. 이층구조(ITO/PPV)Polymer matrix+PBD/Mg)에서는 PMMA (poly(methyl methacrylate)), PC(polycarbonate) PS 와 MCH(side chain liquid crystalline homopolymer)를 고분자 메트릭스로 사용하였으며, 특히, PS 고분자 메트 릭스를 전자수송층으로 사용하는 경우에 전자수송제인 PBD의 농도에 따른 발광휘도 특성을 구하였다. 제작된 소자의 인가전압에 따른 전류, 휘도특성을 분석한 결과 터널링효과를 나타내었고 안정된 발광특성을 가진다는 것을 알 수 있었다.

• 센서학회지
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• 제32권4호
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• pp.252-256
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• 2023

A one-step method for nanoscale patterning of silver ionic ink on a substrate is developed using a microscale, elastic mold deformation. This method yields unique micro/nanoscale metallic structures that differ from those produced using the original molds. The linewidth of these metallic structures is significantly reduced (approximately 10 times) through the sidewall deformation of the original mold cavity on a thin liquid film, as verified by finite element analysis. The process facilitates the fabrication of various, isolated and complex micro/nanoscale metallic structures with negligible residual layers at low cost and high throughput. These structures can be utilized for various applications, including optoelectronics, wearable sensors, and metaverse-related devices. Our approach offers a promising tool for manipulation and fabrication of micro/nanoscale structures of various functional materials.

• 해양환경안전학회지
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• 제28권spc호
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• pp.30-36
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• 2022

수처리 후 직접 해양으로 배출하는 산업시설 등에서 Hazardous and Noxious Substance (HNS) 농도 변화를 연속 자동 측정하기 위한 센서의 기본적 성능으로 상온에서도 ppb 수준의 검출이 가능한 센서가 필요하다고 판단하여 기존의 센서의 감도를 높이기 위한 방법을 제안하였다. 우선 나노입자 박막에 전도성 탄소계 첨가물을 이용하여 필름의 전도도를 높이는 방법과 촉매 금속을 이용하여 표면에서의 이온 흡착도를 높이는 방법에 대해서 각각 연구하였다. 전도성 개선을 위해서 ITO 나노입자를 활용한 필름에 carbon black을 첨가물로 선택하여, 첨가물 함유량에 따른 센서의 성능변화를 관찰하였다. 그 결과 CB 함량 5 wt% 정도에서 전도성 증가에 의한 저항과 응답시간의 변화를 관찰할 수 있었고, 유기용제를 대상으로 한 실험에서 검출하한은 250 ppb 정도까지 낮아지는 것을 확인하였다. 또한 액체 중 이온 흡착도를 높이기 위하여 센서 표면에 촉매로 Au를 스퍼터로 제작한 표면 촉매층을 형성한 시료를 이용한 실험에서 센서의 응답은 20% 이상 증가하고 평균 검출하한은 61 ppm까지 낮아지는 것을 확인하였다. 이 결과로부터 금속산화물 나노입자를 활용한 화학저항형 센서가 상온에서도 수십 ppb 정도의 HNS를 검출할 수 있다는 것을 확인하였다.

• 센서학회지
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• 제26권4호
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• pp.274-279
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• 2017

LCD(Liquid Crystal Display) panel cutting problem is a sort of two dimensional cutting stock problem. A cutting stock problem is problem that it minimizes the loss of the stock when a stock is cut into various parts. In the most research of the two dimensional cutting stock problem, it is supposed that the relative angle of a stock and parts is not important. Usually the angle is regarded as horizontal or perpendicular. In the manufacturing of polarizing film of LCD, the relative angle should be maintained at some specific angle because of the physical and/or chemical characteristics of raw material. We propose a mathematical model for solving this problem, a two-dimensional non-Guillotine cutting stock problem that is restricted by an arranged angle. Some example problems are solved by the C++ program using ILOG CPLEX classes. We could get the verification and validation of the suggested model based on the solutions.

• 센서학회지
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• 제19권5호
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• pp.398-402
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• 2010

The liquid phase epitaxy(LPE) method was widely used to growth of mercury cadmium telluride(MCT) thin films. However, this method lead to Hg-vacancies in MCT thin film, because Hg has high vapor pressure at this temperature range. This is a well known defect in HgCdTe grown by LPE method. In this study, we report the development of techniques for improving the crystalline quality and controlling the composite uniformity of HgCdTe thin films using high- pressure Hg-ambient annealing method. As a result, we achieved the improvement of the composite uniformity of HgCdTe thin films. It was observed by the high angle annular dark field scanning TEM(HAADF-STEM) analysis. Moreover, new HgTe phase and a shrinking of lattice fringe were observed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.395-398
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• 2002

Many research group started study to develope x-ray detector using thin film transistor from 1970. But realization of TFT based x-ray detector development was caused by progress of thin film transistor liquid crystal display(TFTLCD) device technology in 1990. The main current of TFT technology is display device. Research results expend TFT technology field from display device to sensor manufacture technology. These days many research group in the world realize various digital x-ray detector. In this study, We compare discharge erasing method to visible light erasing method in a-Se based digital x-ray detector. Visible light erasing method is known reset process in direct conversion x-ray detector. Digital x-ray detector using visible light erasing method is not adaptive for conventional x-ray device, because of its thickness. And it is not avaliable for real-time imaging for digital fluoroscopy, because of its long reset time. In this study we overcome these limitations and show new idea for real-time imaging method.

• 한국광학회지
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• 제28권1호
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• pp.9-15
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• 2017

실리콘 기판으로 만든 바이오센서에서 펩타이드-항체의 접합 동특성을 회전 타원분광계로 정밀하게 측정하고 분석하였다. 극도로 낮은 몰농도의 펩타이드를 측정할 때, 시료가 놓이는 바이오센서의 표면의 불완전한 편평도와 완충용액 굴절률 변화로 인한 측정오차를 줄이기 위하여 금속박막의 유리 프리즘 대신에 실리콘 기판 위에 덱스트란 SAM을 직접 적층하여 바이오센서를 만들었다. $100{\mu}l/min$의 완충용액 주입속도에서 바이오센서에 올려진 항체 및 펩타이드의 접합특성을 각각 측정하였다. 리터당 5 ng의 낮은 항체농도에서도 항체-덱스트란 SAM 사이의 동특성을 쉽게 측정할 수 있었다. 또한 100 nM까지의 펩타이드에 대한 미세한 흡착 및 해리 특성을 정밀하게 측정할 수 있었으며, 접합 동특성 식에 이 실험결과를 피팅하여 흡착계수와 해리계수를 구할 수 있었다. 이 결과로부터 펩타이드의 평형상태의 해리상수인 $K_D$는 97 nM이었고, 이 수치는 Class I에 속함을 알 수 있었다.