• 한국지하수토양환경학회지:지하수토양환경
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• 제8권2호
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• pp.1-8
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• 2003

Chlorofluorocarbons(CFCs) 조사를 위한 지하수 시료 채취 방법 중 cold-welded copper tube method(구리관법)과 flame-sealed borosilicate glass ampule method(유리앰퓰법)의 두 방법을 비교하고 검토하였다. 구리관법에 의해 채취된 시료의 CFCs 농도는 중복시료간에 재현성이 불량한 반면, 유리앰퓰법은 상대표준오차가 5％ 이내로 좋은 재현성을 보여주었다. 이것은 구리관법을 적용할 때, 관정의 출수구와 구리관의 연결의 밀봉성이 좋지 않았기 때문인 것으로 추정된다. 또한 구리관법에 의한 CFCs 농도는 전체적으로 유리앰퓰에 의한 값보다 높았으며 이러한 특징은 CFC-11이 CFC-12보다 더 두드러졌다. 구리관법의 경우에 플라스틱 관이나 관정에 설치된 출수구에 포함된 고무 패킹 등이 시료를 CFCs로 오염시켰을 것으로 평가된다. 유리앰퓰법을 적용했을 때에는 이러한 가능성을 제거하기 위해 stainless steel과 nylon 재질만을 이용하고, 시료채취장비를 관정의 주배수관에 직접 연결하였다. 인위적인 공급원에 의한 CFCs가 없을 것으로 예상되는 시료에서 유리앰퓰법에 의해 매우 낮은 수준의 CFCs농도가 측정됨으로써 이 시료채취과정의 유효성이 검증되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.59-68
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• 2012

This study provided sorption properties of chlorofluorocarbons (CFCs), and elucidated potential application of CFC sorption data in hydrogeochemistry. Prior sorption studies were reviewed for hydrophobic organic compounds similar to the CFCs, because there were only few CFC sorption studies. The CFCs are regarded as relatively conservative chemicals in groundwater environments based on their moderate hydrophobicity. However, thermally altered carbonaceous matter (TACM) can significantly increase sorption capacity and nonlinearity for hydrophobic organic compounds such as CFCs, compared to general soil organic matter. CFC sorption behavior are close to the sorption for reviewed organic chemicals. Therefore, the CFC sorption data can be used for determining hydrogeochemical properties and predicting transport of organic contaminants in TACM-containing aquifer environments.

• 자원환경지질
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• 제40권1호
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• pp.129-140
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• 2007

대기와 물에서의 CFCs(CFC-12, CFC-11, CFC-113)를 분석할 수 있는 시스템을 자체 제작된 퍼지-트랩 추출 장치와 전자포획검출기가 설치된 가스 크로마토그래피를 이용하여 구축하였다. 대기와 물에 대한 시료 채취방법도 확립되었다. 분석 시스템은 실험적으로 최적화되어 최근 대기 시료는 2% 이내, 제주도의 지하수 시료 (CFC-12 농도가 $160{\sim}180pg/kg$)는 5% 이내의 삼중복시료에 대한 재현성을 보였고, 미국지질조사소(USGS)의 분석시스템과 교차 분석을 실시하였으며, 10% 오차 범위내에서 일치하였다. 한반도 중부 지역의 세 지점에 대해 19개월에 걸쳐 대기 중의 CFCs를 관측하여 이 지역에서 국지적인 CFCs 근원이 크지 않음을 확인하였다. 제주도의 한 농업용 공공 관정에서 2개월 간격으로 1년 동안 지하수의 CFCs를 관측한 결과 8월까지 지하수의 CFCs 농도가 감소하고 10월 이후에 다시 증가하는 계절적인 변동을 보여 주었다. 이것은 여름철 우기에 발생한 지하수 함양이 수 개월 지연되어 나타난 결과로 볼 수 있으며, 제주도 현무암 대수층의 높은 투수성을 지시한다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 춘계학술대회 논문집
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• pp.421-422
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• 2003

Greenhouse gases (GHGs) such as carbon dioxide ($CO_2$), methane (CH$_4$), nitrous oxide ($N_2$O), chlorofluorocarbons (CFCs), sulphur hexafluoride (SF$_{6}$), together with water vapour ($H_2O$) and ozone play an important role in determining the earth's climate. The primary cause of the enhancement of GHGs is the global use of fossil fuels to generate heat, power, and electricity for a growing world population, as well as the changes in the land use, especially for agriculture. In addition, biomass buring and biofuel emissions play major roles in the GHG emissions in the Asian region because they produce large amounts of carbon monoxide (CO), nonmethane volatile organic compounds(NMVOC), black carbon(BC) and other gases. (omitted)d)

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.21-23
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• 2002

Two sampling methods for chlorofluorocarbons(CFCs) in groundwater were compared and assessed with groundwater samples in Jeju Island. CFCs concentrations from copper tube method were widely variable among triplicates and higher than those from flame-sealed glass ampule method. For the copper tube method, this is aggravated by rubber packings in the faucet of discharge line of wells, which was removed for the glass ampule method. The poor reproducibility and apparent contamination of results by copper tube method is due to the improper sealing of copper tubes and materials in water discharge line. This suggests that it is more difficult to achieve complete isolation from the atmosphere in the copper tube method and that materials that could release CFCs should be avoided along the sampling flow lines. It seems that the flame-sealed glass ampule method is more relevant for groundwater sampling for CFCs though it requires more complicated equipments and procedures.

• Environmental Analysis Health and Toxicology
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• 제24권3호
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• pp.213-218
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• 2009

1-bromopropane (1-BP) has been used in numerous purposes such as an intermediate in the synthesis of pharmaceuticals, a solvent for fats, waxes, or resins and a substitute for chlorofluorocarbons that destroy the ozone layer. However, the studies related to the modulation of activities of hepatic cytochrome P450s (CYPs) are not reported yet. This study was the first study to investigate the potential effect for the activities of hepatic CYPs by the treatment of 1-BP in vivo. When 1-BP was treated to male ICR mice by dose-dependently at the dose levels of 200, 500 and 1,000 mg/kg of body weight once, the activity of CYP2E1 was selectively increased for 24 h. The inductive potency for the activity of CYP2E1 by 1-BP was equal to induction by acetone a well-known selective CYP2E1 inducer. The present results indicated that 1-BP would affect the metabolism of 1-BP itself and/or other xenobiotics.

• 한국대기환경학회지
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• 제29권1호
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• pp.27-37
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• 2013

CFCs (Chlorofluorocarbons) and HCFCs (Hydrochlorofluorocarbons) that are chemically stable were proven to be a greenhouse gases that can destroy ozone layer. On the other hand, HFCs (Hydrofluorocarbons) was developed as an alternative refrigerant for them, but HFCs still have a relatively higher radiative forcing, resulting in a large Global Warming Potential (GWP) of 1,300. Current regulations prohibit production and use of these chemicals. In addition, obligatory removal of existing material is in progress. Methods for the decomposition of these material can be listed as thermal cracking, catalytic decomposition and plasma process. This study reports the development of low cost and high efficiency plasma scrubber. Stability of steam plasma generation and effect of plasma parameters such as frequency of power supply and reactor geometry have been investigated in the course of the development. Method for effective removal of by-product also has been investigated. In this study, elongated rotating arc was proven to be efficient in decomposition of HFCs above 99% and to be able to generate stable steam plasma with steam contents of about 20%.

• 한국기계가공학회지
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• 제19권3호
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• pp.51-56
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• 2020

Research into natural refrigerants that use CO₂, instead of chlorofluorocarbons and hydrofluorocarbons, has increased due to the environmental problems caused by ozone depletion. CO₂ refrigerants are more environmentally friendly than conventional refrigerants because they have better latent heat of evaporation and heat transfer efficiency properties. However, they have very low critical temperatures and require high design pressures; therefore, pressure control valves, which reduce the pressure of the CO₂ refrigerant to a safe level and apply it to the refrigerant air conditioning system, are necessary to secure stability against high pressure. In the present study, we evaluated the flow characteristics and valve performance of the pressure control valve using a CO₂ refrigerant by measuring the pressure, velocity, and flow coefficient. In addition, we examined the applied forces caused by the internal pressure from the highly pressurized CO₂ refrigerant and required thrust characteristics.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.73-76
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• 2003

SF$_{6}$ (Sulfur Hexafluoride) is a gaseous compound whose use is being greatly increased recently. The compound has a negligible background concentration from natural sources and is stable in most of groundwater environments. Therefore, SF$_{6}$ has potential for a dating tool for young groundwater. It has many advantages over chlorofluorocarbons (CFCs) for groundwater investigation that sampling procedure is much simpler than CFCs and its growth is continued up to at least near future in the atmosphere. However, solubility of SF$^{6}$ is so low that excess air causes large uncertainties in recharge date of groundwater. To compensate the limitation, $N_2$/Ar method can be employed to estimate excess air content. A groundwater study is currently carrying out in Jeju Island using SF$_{6}$ as an environmental tracer, Well waters and spring waters were sampled for SF$_{6}$ and $N_2$/Ar. To establish SF$_{6}$ input history in the study area, air sampling is being conducted in the area near the center of the island on a monthly and weekly basis. Based on the present data, the level of SF$_{6}$ concentration in the atmosphere of the Island is corresponding to the trend of the Northern Hemisphere.

• 한국가스학회지
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• 제18권5호
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• pp.85-90
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• 2014

대용량의 공기조화용으로 널리 사용되는 터보냉동기는 냉매로 HCFC-123 가스를 주로 사용하며, HCFC-123은 CFC계 프레온의 대체 냉매제로 독성은 낮으나 환기가 원활하지 않는 밀폐공간이나 작업공간에서 산소결핍으로 인한 질식재해를 유발할 수 있는 것으로 보고되고 있다. 본 연구에서는 2011년 대형할인마트 기계실 내부 터보냉동기 냉매 누출로 인해 작업자 4명이 질식 등의 사유로 사망한 재해 사례를 대상으로 전산유체역학을 이용하여 HCFC-123 누출에 따른 산소농도를 예측함으로써 프레온 가스 누출사고에 대한 원인을 조사하고 대응책을 제시하여 동종 재해의 재발 방지에 도움이 되고자 한다.