• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.381-387
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• 2007

The excellent dielectric properties of $SF_6$(sulfur hexafluoride) have lead to its wide range of application in the field of high voltage insulation. Because there has been some recent concern regarding the environmental impacts of $SF_6$ binary gas mixtures, with $SF_6$ as the main component, have been the subject of active research. Scientists have long been interested in the possible use of gaseous fluorocarbons, including $CF_4$ (Carton Tetrafluoride), in high voltage applications due to their inert character and high dielectric strength. This paper presents experimental results concerning the AC breakdown characteristics lot various mixtures of $SF_6/CF_4$ in a test chamber and 25.8 kV GIS (Gas Insulation Switchgear) at practical pressures (0.1-04 MPa) and gap lengths (0.5 mm, 1 mm) in a test chamber. In the result, it was observed that an increase in the dielectric strength is attained through the addition of $SF_6$ to $CF_4$. It is possible to make an environment friendly gas insulation material while maintaining the dielectric strength by combing $SF_6$ and $CF_4$ which generates a lower level of the "global warming" effect.

• 한국초전도ㆍ저온공학회논문지
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• 제13권1호
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• pp.27-30
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• 2011

A sub-cooled liquid nitrogen cooling system is known as a most promising method to develop large scale superconducting apparatuses such as superconducting fault current limiters and superconducting cables [1]. Gaseous helium (GHe), gaseous nitrogen ($GN_2$) and sulfur hexafluoride ($SF_6$) are commonly used for designing an high voltage applied superconducting device as an injection gaseous medium [2, 3]. In this paper, the analysis on the dielectric characteristics of GHe, $GN_2$ and $SF_6$ are conducted by designing and manufacturing sphere-to-plane electrode systems. The AC withstand voltage experiments on the various gaseous insulation media are carried out and the results are analyzed by using finite element method (FEM) considering field utilization factors (${\xi}$). It is found that the electric field intensity at sparkover ($E_{MAX}$) of insulation media exponentially decreases according to ${\xi}$ increases. Also, the empirical expressions of the functional relations between $E_{MAX}$ and ${\xi}$ of insulation media are deduced by dielectric experiments and computational analyses. It is expected that the electrical insulation design of applied superconducting devices could be performed by using the deduced empirical formulae without dielectric experiments.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.8-14
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• 2014

Brightness temperature spectra acquired from FTIR(Fourier Transform Infrared)-SCADS (Standoff Chemical Agent Detection System) could be available for detection and identification of the chemical agents and pollutants from different background. IR spectrum range of 770 to 1350 $cm^{-1}$ is corresponding to "atmospheric window". A 2-dimensional(2D) brightness temperature spectrum was drawn from combining each data point through automatic continuous scanning of FTIR along with altitude and azimuth. At higher altitude, temperature of background was decreased but scattering effect of atmospheric gases was increased. Increase in temperature difference between background and blackbody in SCADS at higher temperature causes to increases in peak intensity of $SF_6$. This approach shows us a possibility that 2D visual information is acquired from scanning data with a single FTIR-SCADS.

• 멤브레인
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• 제19권3호
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• pp.244-251
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• 2009

본 연구에서는 폴리이서설폰(polyethersulfone, PES) 중공사 막을 이용하여 6대 온실가스에 속하는 육불화황($SF_6$)을 질소 중에서 분리하고자 하였다. 제막 조건에 따른 막의 구조와 성능변화를 관찰하기 위하여 다른 비용매(아세톤, 에탄올)와 에어갭(air-gap) 그리고 실리콘 코팅을 통하여 성능변화를 관찰하였으며, 전자주사현미경(scanning electron microscope)을 통하여 구조 변화를 관찰하였다. $N_2$, $SF_6$ 단일기체 투과실험에서 제조된 막의 표면 실리콘 코팅을 통하여 최고 7.64의 선택도를 나타내어 3.4배 향상된 결과를 나타내었다.

• Progress in Superconductivity
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• 제13권3호
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• pp.189-194
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• 2012

Studies on the development of high voltage superconducting apparatuses, such as transmission superconducting fault current limiters (SFCLs) and superconducting cables, have been performed worldwide. In this paper, a study on the electrical insulation characteristics of electro negative gas according to various pressures and utilization factors was conducted as a part of developing a high voltage superconducting coil with a sub-cooled nitrogen cooling system. Some gases such as helium (He), nitrogen ($N_2$), and sulfur hexafluoride ($SF_6$) are considered for pressurizing the sub-cooled nitrogen cooling system of high voltage SFCLs and superconducting cables. $SF_6$ is used to pressurize and enhance the dielectric performance of a superconducting system of a sub-cooled nitrogen cooling system for superconducting cables being developed in the Republic of Korea. In this paper, dielectric experiments on AC voltage, as well as lightning impulse voltage of $SF_6$, are conducted according to various utilization factors by using several kinds of sphere-to-plane electrode systems. As results, it is known that the empirical formulae of $SF_6$, known as an electro negative gas, are derived according to various pressures and utilization factors. Also, the appropriate pressure condition for designing a high voltage superconducting coil is found from the viewpoint of dielectric performance.

• 멤브레인
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• 제22권3호
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• pp.201-207
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• 2012

본 연구에서는 PDMS (poly-dimethylsiloxane)와 PEBAX (polyether block amides) 분리막을 이용해 $N_2$, $O_2$, $CF_4$와 $SF_6$의 단일 기체 투과특성에 관하여 연구하였다. 다양한 압력으로 공급된 기체의 투과유량을 진공가압 연속흐름방식으로 측정하였으며, 이를 이용하여 투과도를 산정하였다. PDMS 분리막에서는 상부의 압력이 증가할수록 $SF_6$를 제외한 다른 기체의 투과도는 감소하였다. 또한 $SF_6$의 투과도가 $CF_4$보다 높게 나타나고 있으며 이것은 $SF_6$가 더 높은 임계온도를 가지고 있기 때문이다. PDMS 분리막에서 투과도는 $O_2$ > $N_2$ > $SF_6$ > $CF_4$ 순으로 감소하였다. 반면에 PEBAX 분리막에서 기체의 투과 경향은 $O_2$ > $N_2$ > $CF_4$ > $SF_6$ 순으로 감소하였다. 이러한 경향은 각 기체의 운동 반경의 크기(${\AA}$)($SF_6$ > $CF_4$ > $N_2$ > $O_2$) 순서와 반대로 나타났다. $SF_6/CF_4$의 순수 기체의 선택도는 PDMS 분리막에서 0.7 MPa일 때 2.1로 나타났다.

• 한국결정성장학회지
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• 제19권5호
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• pp.228-236
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• 2009

본 연구에서는 $SF_6$ 가스 포접 하이드레이트 결정이 생성되고 성장하는 메커니즘의 특성을 기술하였다. 실험은 일정한 압력과 온도에서 2상 실험($SF_6$ 기상/수용액상)과 3상 실험($SF_6$ 기상/수용액상/$SF_6$ 액상)의 서로 다른 두 가지 상 조건에서 이루어졌다. 두 조건 모두 기체 영역과 수용액 영역 사이의 경계면에서 하이드레이트 결정의 수지상이 섬유상 형태로 상향 성장하는 거동을 보였다. 3상 실험의 경우 하이드레이트 생성이 진행됨에 따라, 반응기 내부압의 감소로$SF_6$ 액상에서 생성된 기포가 기체와 수용액 계면의 막에 도달하여 기포의 표면이 하이드레이트로 전환되었다. 본 논문에서는 결정의 핵생성과 이동, 성장, 간섭을 중심으로 $SF_6$ 가스하이드레이트 결정의 성장 특성을 기술하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.944-949
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• 2006

An infiltration was realized as an important part of ventilation to change fresh air with contaminated air in a house. In this study, it was measured the infiltration in new apartment buildings according to Seasons, height etc. We measured the infiltration by using tracer gas method and did for 24hours. To quantify the infiltration, Sulfur Hexafluoride($SF_6$) gas was used. The Constant Concentration was conducted during experimental process and the concentration of the gas was measured with a gas monitor. In the results of the measurement, the infiltration were appeared over 0.6 ACH in winter and about 0.2 ACH in summer and autumn. Also the infiltration were measured more highly at high and low stories than middle stories in winter.

• 한국도시환경학회지
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• 제18권4호
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• pp.523-530
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• 2018

오존층의 파괴물질인 CFCs의 대체물로써 $SF_6$의 사용량이 늘어나면서 대기 중의 $SF_6$의 농도가 높아지고 있다. $SF_6$은 지구온난화가스중의 하나로써 대기 중에서 3,200년 이상 머무를 뿐만 아니라 온난화지수도 매우 높아 무려 22,800이나 된다. 그러나, 대기 중에서의 $SF_6$ 농도는 낮은 수준이어서 검출한계이하인 경우가 많다. 본 연구에서는 이러한 극미량 $SF_6$ 농도를 정확하게 분석하기 위해서 $GC-{\mu}ECD$를 이용한 12가지 분석방법을 실험적으로 고찰하였다. 극미량 $SF_6$ 농도를 가장 정확하게 분석할 수 있는 방법은 Carboxen-1000 물질을 사용한 흡착관과 저온농축 고온탈착 방식의 농축장치에 역추출방식의 분석법을 사용할 경우가 최상의 효율을 나타냈다.