• 한국대기환경학회지
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• 제33권4호
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• pp.370-376
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• 2017

This study was performed to investigate whether the decomposition process of $SF_6$ using an electron beam is economically reasonable when applied to the actual field. To do this, electron beam experiment and economic analysis were conducted. The experiment conditions are initial concentration of 1% of $SF_6$, 1 mA of input energy and 15 mA of flow rate with $H_2$ as an additive which were obtained from our previous research. As a result, removal efficiency of $SF_6$ was 90% for 8 hours continuously. In addition, economic analysis shows positive results in terms of using $SF_6$ decomposition process using electron beam. According to the analysis, the revenue is approximately 1.66 billion won in the first year and 3 billion won in the second year.

• 한국대기환경학회지
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• 제5권2호
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• pp.84-96
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• 1989

To evaluate the short term air pollution dispersion model, the diffusion experiment was conducted on the flat terrain near Chuncheon. Sulfur hexafluoride $(SF_6)$ gas was used to determine the horizontal spread of plume $(\sigmay)$ for calculated by CRSTER model. Results show that CRSTER model underestimates $\sigma$y because averaging time adjustment is not applied to calculate the $\sigma$y. The scheme that can estimate the atmospheric stability more accurate than Turner method, was presented.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• Asian-Australasian Journal of Animal Sciences
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• 제20권7호
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• pp.1049-1056
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• 2007

This study was conducted to compare the methane ($CH_4$) production estimated by in vivo (sulfur hexafluoride tracer technique ($SF_6$)) with that of two in vitro rumen simulation (RUSITEC) and gas production (IVGPT)) techniques. Four adult dry Holstein cows, aged $7.4{\pm}3.0$ years and weighing $697{\pm}70$ kg, were used for measuring methane production from five diets by the $SF_6$ technique. The experimental diets were alfalfa hay ($D_1$), corn silage + soybean meal (SBM) (910: 90, $D_2$), Italian rye grass hay +SBM (920: 80, $D_3$), rice straw +SBM (910: 90, $D_4$) and Sudan grass hay +SBM (920: 80, $D_5$). Each diet was individually fed to all 4 cows and 5 feeding studies of 17 d each were conducted to measure the methane production. In the RUSITEC, methane production was measured from triplicate vessels for each diet .In vitro gas production was measured for each of the diets in triplicate syringes. The gas produced after 24 and 48 h was recorded and gas samples were collected in vacuum vials and the methane production was calculated after correction for standard temperature and pressure (STP). Compared to the $SF_6$ technique, estimates of methane production using the RUSITEC were lower for all diets. Methane production estimated from 24 h in vitro gas production was higher (p<0.001) on $D_1$ as compared to that measured by $SF_6$, whereas on $D_2$ to $D_5$ it was lower. Compared to $SF_6$, methane production estimated from 48 h in vitro gas production was higher on all diets. However, methane estimated from the mean of the two measurement intervals (24+48 h/2) in IVGPT was very close to that of $SF_6$ (correlation 0.98), except on $D_1$. The results of our study confirmed that IVGPT is reflective of in vivo conditions, so that it could be used to generate a database on methane production potential of various ruminant diets and to examine strategies to modify methane emissions by ruminants.

• 대한환경공학회지
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• 제33권1호
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• pp.47-53
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• 2011

$SF_6$는 IPCC가 평가한 온난화 지수가 가장 큰 물질이다. 이런 $SF_6$ 가스의 처리를 위하여 현재는 고에너지의 분해 기술이 사용되고 있지만 최근 분리막을 이용한 분리 및 회수 기술이 주목을 받고 있다. $SF_6$가 중간권으로 방출될 경우 광분해 또는 이온 반응을 일으켜 높은 독성과 부식성을 지닌 부산물을 발생시키는 문제점을 가지고 있다. 현재 분리막을 이용한 $SF_6$ 가스의 회수 분리에 관한 연구 동향을 살펴보면 다양한 분리막 재질에 대한 투과특성연구가 부족하다. 또한, 실제 폐 $SF_6$ 가스 농도에 대한 연구와 에너지 효율이 높은 운전조건의 분리 회수 연구는 초기단계이다. 그러므로, 본 연구에서는 상용화된 PSF (polysulfone), PC (tetra-bromo polycarbonate)와 PI (polyimide) 중공사 분리막을 사용한 $SF_6$, $N_2$ 단일기체의 투과도 연구 및 폐 $SF_6$ 가스 농도의 $SF_6/N_2$ 혼합기체를 사용하여 상용화된 PSF, PC와 PI 중공사 분리막과 운전조건 변화에 따른 $SF_6$ 가스의 분리 회수 연구를 수행하였다. 고분자 중공사 분리막에 대한 $SF_6$와 $N_2$의 투과 특성 실험 결과, $N_2/SF_6$ 투과선택도는 PI 중공사분리막이 가장 높고, PC 중공사 분리막이 가장 낮은 결과를 보였다. $SF_6/N_2$ 혼합기체의 분리 특성연구에서 회수된 $SF_6$의 농도를 비교할 경우, PC 중공사 분리막이 0.5 MPa일 때 95.6 vol %로 가장 높았다. $SF_6$의 회수율에서는 PSF 중공사 분리막이 운전압력 0.3 MPa, 배출유량 150 cc/min일 때 최대 97.8%로 가장 높았다. 이상의 결과로부터 분리막을 이용한 폐 $SF_6$ 가수의 분리 및 회수 기술은 향후 $SF_6$ 가스의 대표적 친환경 기술로 활용될 수 있을 것으로 생각된다.

• 멤브레인
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• 제26권2호
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• pp.159-165
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• 2016

다단기체분리 공정을 수행하기 위해 폴리이미드 중공사막 모듈을 제조하여 혼합기체 $N_2$ : $SF_6$ = 50 : 50에 대한 기체분리특성을 확인하였다. 제조된 중공사막 모듈은 0.5 MPa에서 stage cut을 조절하여 투과 유량, 농도 등의 성능을 측정하였다. 중공사막 모듈은 1단 분리 테스트에서 $N_2/SF_6$ 선택도가 높을수록 동일한 stage cut에서 높은 $SF_6$ 회수율을 얻을 수 있었다. 1단 시험결과에 따라 $SF_6$ 회수율과 농축농도를 동시에 높이기 위해 2단 기체 분리 테스트 진행함으로써 $SF_6$ 회수율 95% 이상, $SF_6$ 회수농도 98% 이상을 농축할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.122.2-122.2
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• 2011

Sulfur hexafluoride ($SF_6$), one of the most potent greenhouse gases, is known as a hydrate former and has been studied at the high pressure up to 1.3 GPa with gas mixtures and with aqueous surfactant. Since we regard $SF_6$ as a potential promoter molecule that can stabilize hydrate structure more effectively compare to the other promoters, further investigation is required to verify the stabilizing ability of $SF_6$ in the hydrate structure. However, the insoluble nature of $SF_6$ in water or gases hinders fine scale analyses. This work discusses the data obtained by using molecular dynamics simulations of structure II (sII) clathrate hydrates containing $SF_6$ and $H_2$. The simulations were performed using the TIP4P/Ice model for water molecule and a previously reported $SF_6$ molecular model (optimized at the pure $SF_6$ single phase system (Olivet and Vega, 2007)), and a $H_2$ molecular model (adapted from the THF+$H_2$ hydrate system (Alavi et al., 2006)). The simulations are performed to observe the stability of $SF_6$ and $H_2$ in the sII clathrate hydrate system with varying temperature and pressure conditions and occupancies of $SF_6$ and $H_2$, which cannot be easily tuned experimentally. We observe that stability of H2 enclathrated in the hydrate structure more affected by the occupancy of $SF_6$ molecules and temperature than pressure, which ranges from 1 to 100 bar.

• 한국전기전자재료학회논문지
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• 제27권3호
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• pp.172-177
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• 2014

Industrial, medical, environment and agriculture application of pulse power technology have been developing rapidly in many field. In order to make use in the form of pulses is applied to the pulse forming technique. At this time, spark gap is generally used for the pulse forming. Spark gap may be possible to simulate the shape of the electrode, to know the uniform or non-uniform electric field of the electrode structure. Further, it can be determined using Paschen's law applied pressure of the insulating gas in accordance with the voltage which is created using the value of the electric field. In this paper, we tried to found using a formula and the simulation process to determine the pressure. The value of the electric field is different according to the shape of the electrode. So, the range of pressure applied also varies. In order to withstand the 100 kV with a gap of 5 mm, the nitrogen gas must be applied to about 7 bar in the electrode structure. On the other hand, in the same conditions, Sulfur hexafluoride gas must be applied to about 2 bar. Consequently, the Sulfur hexafluoride gas has a higher insulation properties than nitrogen gas may be applied to low pressure at the same conditions.

• 한국대기환경학회지
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• 제33권4호
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• pp.326-332
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• 2017

$SF_6$ (sulfur hexafluoride) gas has an extremely high global warming potential (GWP). Therefore, there has been an effort to reduce of $SF_6$ its emission into atmosphere. In this study, $SF_6$ was injected into the plasma reactor directly, decomposed particulate matter of $SF_6$ was analyzed. Destruction and removal efficiency (DRE) of $SF_6$ were tested with varying degrees of plasma power and initial concentrations of $SF_6$ (1,000 ppm). This study is conducted with plasma power which are 4.4 kW, 5.5 kW, 6.0 kW, 6.6 kW, 7.6 kW, 8.1 kW and 9.1 kW. It was confirmed through experiment that the decomposition efficiency of $SF_6$ is 100% at 7.6 kW of the plasma power. In addition, the particulate matter is formed as minute particles of which size is $1{\mu}m$ and the main component of particulate matter is identified as $AlF_3$.

• 한국재료학회지
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• 제18권2호
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• pp.73-76
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• 2008

[ $SF_6$ ] gas has been widely used as an insulating, cleaning and covering gas due to its outstanding insulating feature and because of its inert properties. However, the global warming potential of $SF_6$ gas is extremely high relative to typical global warming gases such as $CO_2$, CFCs, and $CH_4$. For these reasons, it is necessary to separate and collect waste $SF_6$ gas. In this study, the effects of a surfactant (Tween) on the formation rate of $SF_6$ gas hydrates were investigated. The $SF_6$ gas hydrate formation rate increased with the addition of Tween and showed a nearly 6.5 times faster hydrate formation rate with an addition of 0.2 wt.% Tween compared to an addition of pure water. This is believed to be due to the increased solubility of $SF_6$ gas with the addition of the surfactant. It was also found that $SF_6$ gas hydrate in the surfactant solution showed two-stage hydrate formation rates with a formation rate that increased rapidly in the 2nd stage.