• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.94-94
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• 2003

위성체의 유기오염은 광학계 렌즈 등의 오염 민감 표면에 분자단위로 흡착되어 표면에 층을 이루며 존재하는 것으로 위성의 성능저하 및 임무실패를 야기할 수 있는 주요원인이 된다. 유기오염은 단순히 대기에 노출되는 것만으로도 발생할 수 있으며, 특히 고온 고진공 상태에서는 다른 표면들에서 outgassing된 물질들이 흡착될 수 있기 때문에 그 영향이 극대화 된다. 본 연구에서는 이러한 유기오염을 측정하기 위하여 청정실과 열진공챔버 내에 witness plate를 설치하고 이를 적외선분광장비로 분석하였다. 적외선 분광장비를 이용하여 ESA(European Space Agency) 문서를 기준으로 4가지 물질에 대하여 검교정을 수행하였고, 그 결과를 바탕으로 유기오염물을 정량분석 하였다. 또한 유기오염물질의 분별을 통해 보다 정확한 분석을 수행하기 위하여 GC-MS(Gas Chromatograph - Mass Spectrometer)를 사용하여 분석을 시도하였으며, 이를 국제 기준에 적용하기 위한 방안도 모색하였다.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.479-482
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• 2004

Laminate Design of a composite tube for a space telescope(Fig. 1) under hygrothermal load is studied. Carpet plots for laminate effective engineering constants are generated and used for selecting the best tube lay-ups satisfying the optomechanical requirements for a space telescope being dimensional1y stable under orbital thermal loading. Despace of the tubes constructed with the selected lay-ups are calculated with a Zig-Zag Triangular Element which accurately represents through thickness stress variations for laminated structures. The effects of moisture absorption when exposed to humidity environment and moisture desorption through outgassing on the dimensional stability are also investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.175.1-175.1
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• 2014

Despite growing interest in Ge as a possible alternative to Si, reliable data on Ge surface has been relatively scarce. Using low temperature scanning tunneling microscopy (STM), we investigate band-bending effects of localized charge traps at Ge(001) surface at 78 K. For this investigation, we prepared nearly defect-free Ge(001) surface by keeping the background pressure to < $1{\times}10^{-10}$ mbar during outgassing. Ge(001) surfaces this obtained exhibit a flat-band condition, and deposition of charge traps induce a distinct, sharp boundary between pinned and depinned surface area in the constant current mode STM images. We will show the tip-surface interaction plays an essential role in producing the boundary, and discuss about the conditions that enable the pinning effect.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.356-356
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• 2011

챔버 내부의 압력은 gauge가 달려 있는 몇몇 지점에만 국한되어 읽을 수 있었기 때문에 gauge를 이용한 압력 측정을 통해 보다 상세한 진공도를 구하기란 쉽지 않다. 챔버 내부의 압력은 빔 운전에 적합한 초고진공을 유지하여야 하고, 균일하여야 하므로 신뢰 할 수 있는 방법으로 진공도를 정확히 계산해 볼 필요가 있다. 그리하여 압력에 영향을 미치는 여러 가지 진공 시스템 내부의 요소인 Outgassing, 배기속도, 컨덕턴스, 압력 등을 mass balance equation을 이용해 수식화 하여 정리한다. 이 수식을 가지고 FEA(Finite element analysis)프로그래밍을 이용해 진공도를 계산한다. FEA 프로그래밍에 쓰이는 프로그램은 Matlab, excel을 이용하였다. 이 프로그래밍 결과에 따라 Pressure Profile을 작성 하고, 시간이 변함에 따라 진공도가 어떻게 변하는지 실제로 계산하여 time constant를 구한다. 이 값들을 챔버를 가지고 측정한 데이터와 비교하여본다.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.68-72
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• 2002

This work investigates the transient cooling characteristics of an Infrared (IR) detector cryochamber, which has a critical effect on the cooling load. The current thermal modeling considers the conduction heat transfer through a cold well. the gaseous conduction due to outgassing. and the radiation heat transfer. The transient cooling Performance. i.e. the penetration depth and cooling load, is determined using a finite difference method. It is found that the penetration depth increases as the bore conductivity increases. Gaseous conduction and radiation hardly affect the penetration depth. The transient cooling load increases as the bore conductivity increases. The effects of gaseous conduction and radiation on transient heat transfer are weak at initial stages of cooling. However, their effects become significant as the cooling Process Proceeds.

• Journal of the Korean institute of surface engineering
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• v.37 no.3
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• pp.185-190
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• 2004

Plasma Display Panel is a display device emitting fluorescent light from gas discharge between a front and a rear panel sealed together. Front and rear panel have multitude of film layers and barrier ribs in the rear panel has the largest area so releasing various gases and affecting light emitting characteristics and lifetime. The remaining gases in a barrier rib were studied by thermal desorption analysis up to $400^{\circ}C$ and main gases were $H_2$ $H_2$O, CO. During sustaining at $300^{\circ}C$, the outgassing rates from other gases were decreased but$ H_2$ kept constantly increasing until 1 hour, which can be originated from the dissociation of organics remained in the inside of barrier rib material. In $H_2$O, two distinct peaks were observed: desorption from physically adsorbed one at $l00^{\circ}C$ and from chemically adsorbed one $400^{\circ}C$. The result can be utilized in interpretation of electronic and optical characteristics and evacuation process control of PDP

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.38-38
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• 2000

저온유지장치에서 요구되는 도달압력은 초전도 코일의 냉각시스템과 저온유지장치의 벽 사이의 진공단열조건으로부터 결정될 수 있으며, 기체에 의한 열전도의 영향을 방지하기 위해서는 5$\times$105Torr 이하의 진공도가 요구된다. 저온유지장치 내에서 진공 단열재로 사용되는 Glass Fiber Reinforced Plastic(GFRP)과 Carbon Fiber Reinforced Plastic(CFRP)의 기체 방출률을 측정하였다. 고출력 토카막 방전동안 graphite limiter 표면의 온도는 200$0^{\circ}C$ 이상이며, 플라즈마로 유입되는 불순물의 양을 줄이기 위해 많은 시도를 하고 있다. 상온에서부터 약 100$0^{\circ}C$까지 승온에 따른 방출기체의 양 및 성분 분석, annealing 후 공기 중에 약 2주간 노출 후 기체 방출률과 성분을 분석하였다. 총 기체 방출량은 10$0^{\circ}C$ 근방에서 급격히 증가하여 $600^{\circ}C$부터는 graphite의 종류에 관계없이 거의 일정한 분포를 보이며, 최대 방출률은 약 20$0^{\circ}C$~30$0^{\circ}C$ 부근에서 나타났다.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.52-52
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• 2000

저진공 펌프 제작시 ISO, AVS 등의 국제규격에 ？춤은 필수이고, 도달진공도, 압력구간별·가스별 배기속도, 소음, 기름증기 역류, 압축비 등이 이에 해당된다. 큰 체적의 시험용기가 구비되어 있지 않은 경우에는 배기감압법 대신 일정유량 Q를 흘려 시험용기내에 일정압력 P를 유지시키면서 배기속도를 S=Q/P식으로 구하는 일정압력법을 사용한다. 이 실험은 800~2000 l/min급 유회전 펌프와 드라이 펌프로 압력별 배기속도를 측정, 분석하여 평가방법을 수립하였다. 또 국가 유량 표준기인 sonic nozzle을 reference로 하여, 기존의 유량측정 장비와의 오차를 비교하였다. 온도 상승도를 측정, 압력과의 상관관계를 비교하였고, 오차가 적은 CDG(1, 10, 100torr)를 사용하여, 압력측정의 정확도를 높였다. 비교적 outgassing이 적은 SUS 재질의 chamber를 썼고, 유량조절 장치로 미세누출밸브를 사용하였다.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.217-223
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• 2023

In this study, we compared the VacCAD and VacTran, commercial vacuum simulators, to investigate the simulation applicability and efficiency as vacuum simulation software. It was verified on reliability and simplicity of simulation modelling, and characteristics of the pump combinations, pumping down curves, and employed vacuum materials. First, usability of simulation schematics was estimated through the modeling tools and the overall simulation characteristics of each simulator were compared to evaluate the applicability in practice. Simulation reliability of each simulator was also probed by comparing the pumping performance characteristics of commercial high vacuum system models. In addition, the degree of tolerances on both simulators was also evaluated through pumping down analysis considering outgassing effect due to chamber material variations. The higher effectiveness and expediency of VacCAD than VacTran has been presented, and it was also expected that the utilization of VacTan in vacuum applications to be increased due to the higher availability of modelling variations.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.66-72
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• 2010

This study was done to analyze the condition of combustion exhaust gas that is produced according to incinerator operating condition in A area Kyonggido. The boiler exhaust gas temperature, the oxygen concentration of boiler, the outgassing temperature of Semi Drying Sorber(SDS), the temperature of catalytic reactor, the concentration of NOx, SOx, CO, Hcl and Dust were investigated by change the temperature of incinerator. The concentration of SOx, CO, HCL and DUST were below 5 ppm as increase the temperature of incinerator however the concentration of NOx was increased from 40 ppm to 70 ppm as increase the temperature of incinerator. The boiler exhaust gas temperature and the temperature of catalytic reactor were not changed however the oxygen concentration of boiler was decreased gradually as increase the temperature of incinerator.