• 한국대기환경학회지
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• 제20권1호
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• pp.77-85
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• 2004

In this study, the concentrations of reduced S compounds (including hydrogen sulfide (H$_2$S); methyl mercaptan ($CH_3$SH); dimethyl sulfide (($CH_3$)$_2$S); carbon disulfide (CS$_2$); and dimethyl disulfide (($CH_3$)$_2$S$_2$) were determined from landfill gas (LFG) in three municipal landfill sites in the two cities of Gwang Ju (GJ) and Jeju (JJ), Korea. The S gas concentrations measured in these landfill sites were found to be dominated by H$_2$S with its mean concentration of 850 ppm from 10 LFG samples. Both absolute and relative dominance of H$_2$S was seen to be significant in most LFG samples, except those collected from very old and inactive landfills. Unlike the pattern of H$_2$S, other S gases were typically observed at much reduced concentration levels (a few ppm or less) as follows: DMS (3.5); $CH_3$SH (1.3); CS$_2$(1.2); and DMDS (0.02 ppm). If compared equally in mass concentration unit (mg m$^{-3}$ ), H$_2$S generally explained far above 90% of all S gas masses determined concurrently. Moreover, as its mass concentration commonly exceeds those of the major aromatic VOC components in LFG (like benzene and toluene), it appeared to be one of the most dominant gaseous components emitted as LFG in a quantitative sense.

• 한국대기환경학회지
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• 제30권3호
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• pp.211-222
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• 2014

Pork belly meat is one of the most preferred food items for many Korean people. The odorants released from cooking of pork belly meat were measured by three kinds of cooking methods (Charcoal-grill (C), Electric Pan (E), and Gas burner-pan (G)). A total of 16 target compounds including carbonyl compounds, volatile organic compounds, and poly aromatic hydrocarbon were selected and analyzed for comparative purposes. Their emission concentrations were quantified using HPLC-UV, GC-MS, GC-TOF-MS, etc. The gas samples collected by Charcoal-grill cooking showed generally enhanced concentrations of most target compounds among all three kinds of cooking methods. In Charcoal-grill, concentration of benzene, formaldehyde and pyrene went up to 543, 516, and 402 ppb, respectively. It the results are compared in terms of the sum of odor intensity, the highest value (4.25) was also seen from Charcoal-grill. The results of this study confirm that the significantly reduced emission of harmful pollutants can be attained, it pork belly meat is cooked by the Gas or electric pan instead of Charcoal-grill.

• 한국대기환경학회지
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• 제26권1호
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• pp.85-93
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• 2010

$CF_4$ removal characteristics were investigated using an elongated arc reactor. The advantage of the elongated arc reactor includes direct use of treated gas as plasma operating gas and the enhancement of the removal reaction by using a thermo-chemistry and a plasma induced chemistry at the same time. Geometrical configurations, such as the length of the reactor and the shape of a throat, were tested to get an optimized removal efficiency with low power consumption. As results, over 95% of $CF_4$ removal was obtained with 300 lpm of total flowrate for various $CF_4$ concentration (0.1~1%). Corresponding specific energy density (SED), which means required electrical energy to treat the unit volume of treated gas, is about 3.5 kJ/L, The present technique can be applied to real applications by satisfying three major concerns, those are the high flowrate of treated gas, high removal efficiency (> 95%), and low power consumption (< 10 kJ/L).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.261-262
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• 2011

본 연구는 HMDS/$O_2$/He/Ar의 gas mixture를 이용하여 remote-type의 DBD source를 통한 APPECVD를 통한 SiOx 양질의 무기막 증착 공정을 개발하였다. 이때 기판에 바이어스를 인가 하거나 혹은 접지를 하여 대기압 플라즈마의 환경 내에서도 바이어스 효과를 확인할 수 있도록 double discharge system을 구축하였다. 그리고 이 double discharge system의 다양한 특성과 기존의 전형적인 DBD와 비교 하였을 때 어떠한 차이점을 가지는지에 대해서도 관찰하였다. 그리하여 전형적인 DBD system과 double discharge를 통해 증착된 SiOx 무기막의 특성을 역시 비교 관찰하였다. Gas mixture 중 HMDS의 유량이 증가함에 따라, 그리고 $O_2$ gas의 유량이 감소함에 따라 SiOx 무기막의 증착률은 감소하였다. 그러나, SiOx 무기막 내의 불순물들, 예를 들어, carbon 혹은 hydrogen 계열의 chemical bond에 대한 정성적인 양은 HMDS 의 유량이 증가하거나 혹은 $O_2$ gas의 양이 감소함에 따라 오히려 증가함을 관찰할 수 있었다. 그리고 기판에 바이어스를 인가하는 double discharge system을 사용하였을 경우, 같은 HMDS, $O_2$ gas 유량을 사용한 전형적인 DBD type의 증착 공정 보다 더 높은 공정 효율을 나타냄과 동시에 더 낮은 불순물 함량을 가짐을 알 수 있었다. 이러한 double discharge system을 통해 증착된 양질의 SiOx 무기막이 증착 되었음을 FT-IR을 통한 막질 분석을 통해 확인 할 수 있었다. 이러한 double discharge system의 증착 공정에 대한 긍정적인 효과들은 atmospheric discharge의 효율 향상에 따른 gas dissociation efficiency 증가와 이를 통한 HMDS 분해 및 산소와의 recombination 효율의 증가에 따른 결과로 사료된다.

• 대한전자공학회논문지
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• 제21권5호
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• pp.41-45
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• 1984

양질의 에피택셜 층을 성장시키기 위해서는, 에피택셜 층을 성장시키기 직전에 HCl 가스를 사용하여 실리콘 기판을 에칭하는 과정이 거의 언제나 포함된다. 본 논문에서는, 대기압[1 기압]과 감압[0.1기압]에서 HCl 가스 농도와 에칭 온도의 변화에 따른 에칭속도 및 에치-피트 생성에 관하여 조사하였다. 그 결과, 대기압 공정과 감압 공정 모두 에칭 속도는 HCI 가스 농도의 2승[X ]에 비례하였으며, 명목상 활성화 에너지는 0∼11 Kcal/mole인 것으로 나타났다. 이러한 결과로부터, 감압 공정에서 HCl 가스에 의해 실리콘이 에칭되는 것은 대기압 공정에서와 같이 다음과 같은 반응에 의해 일어난다고 예측된다; Si + 2HCl ↔SiCl2 + H2.

• 한국가스학회지
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• 제20권4호
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• pp.15-24
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• 2016

반도체 산업에서 많은 종류의 화학물질 사용으로 인한 독성물질 누출과 화학물질간의 혼화에 따른 화재 폭발 등에 의한 화학사고의 위험성이 증가하고 있다. 화학물질의 혼화에 따른 반응성을 평가하는데 실험적 방법이 가장 신뢰성 있지만, 모든 화학물질을 실험을 통하여 평가하는 것은 시간적, 비용적인 제한이 있다. 본 연구에서는 반도체 산업에서 주로 사용되는 공정가스의 위험성 추정하기 위해 미국 NOAA(National Oceanic and Atmospheric Administration)과 EPA에서 개발한 CRW(Chemical Reactivity Worksheet) 3.0 프로그램을 사용하여 공정가스의 반응성을 고찰하였다. 이들 연구 결과는 반도체산업의 공정가스의 혼화성에 따른 반응성 정보와 저장캐비닛의 가스 실린더 보관에 관한 KOSHA 기술지침 작성에 필요한 기초자료를 제시하고자 하였다.

• 신재생에너지
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• 제19권4호
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• pp.53-60
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• 2023

The Computational Fluid Dynamics (CFD) model is a method of studying the flow phenomenon of fluid using a computer and finding partial differential equations that dominate processes such as heat dispersion through numerical analysis. Through CFD, a lot of information about flow disorders such as speed, pressure, density, and concentration can be obtained, and it is used in various fields from energy and aircraft design to weather prediction and environmental modeling. The simulation used for fluid analysis in this study utilized Gexcon's (FLACS) CODE, such as Norway, through overseas journals, for the accuracy of the analysis results through many experiments. It was analyzed that a technology for treating two or more catalysts with physical properties under low-temperature atmospheric pressure conditions could not be found in the prior art. Therefore, it would be desirable to establish a continuous plan by reinforcing data that can prove the effectiveness of producing efficient synthetic oil (renewable oil) through the application that pyrolysis under low-temperature and atmospheric pressure conditions.

• 드라이브 ㆍ 컨트롤
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• 제12권4호
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• pp.15-20
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• 2015

Unlike a typical metal spring, a gas spring uses compressed gas contained in a cylinder and compressed by a piston to exert a force. A common application includes automobiles where gas spring are incorporated into the design of open struts that support the weight of tail gate. They are also used in furniture such as office chairs, and in medical and aerospace applications. The gas spring works by the application of pressurized gas (nitrogen) contained in a cylinder. The internal pressure of the gas spring greatly exceeds atmospheric pressure. This differential in pressure exists at any rod position and generates an outward force on the rod, making the gas spring extend. In this paper, we investigated the dynamic characteristics of a gas spring on an automotive tail gate system.

• 한국대기환경학회지
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• 제27권1호
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• pp.1-15
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• 2011

Korea Global Atmosphere Watch Center (KGAWC), which is located in Anmyeondo and, belongs to the Korea Meteorological Administration (KMA), measures sulfur hexafluoride ($SF_6$) in every hour since 2007. In this study, $SF_6$ observed in 2007 are discussed. A gas chromatograph-electron capture detector (GC-ECD) with pre-cooled device is applied during the observation, and produced data are qualified by means of periodic calibration with $SF_6$ standard gas made by Korea Research Institute of Standard and Science (KRISS). $SF_6$ has been greatly paid attention since Kyoto protocol because of its high global warming potential(GWP) with 22,200 times of $CO_2$ in the period of 100 years. It is a man-made compound and has been usually used for gas insulation since 1970s and for etching process in the information technology-based industry since 1990. Average mixing ratio of $SF_6$ in 2007 was 6.65 pmol/mol at Anmyeondo. According to the GAW report published in 2008, average mixing ratio of $SF_6$ in the atmosphere is continuously growing. At present, the average mixing ratio of $SF_6$ in the atmosphere is known to be approximately 6.25 pmol/mol at global observatory. $SF_6$ value in Anmyeondo shows 0.40 pmol/mol greater than that of the Mauna Loa observatory in 2007.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.250.2-250.2
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• 2014

Currently, teeth whitening method which is applicable to dental surgery is that physician expertises give medical treatment to teeth directly dealed with a high concentration of hydrogen peroxide and carbamide peroxide. If hydrogen peroxide concentration is too high for treatment of maximized teeth whitening effect [1], it is harmful to the human body [2]. To the maximum effective and no harmful teeth whitening effect in a short period of time at home, we have observed the whitening effect using carbamide peroxide (15%) and a low-temperature atmospheric pressure plasma jet which is regulated by the Food and Drug Administration. The gas supplied conditions of the non-thermal atmospheric pressure plasma jet was with the humidified (0.6%) gas in nitrogen or air at gas flow rate of 1000 sccm. Also, the measurement of chemical species from the jet was carried out using the optical emission spectroscopy (OES), the evidence of increased reactive oxygen species compared to non-humidified plasma jet. We have found that the whitening effect of the plasma is very excellent through this experiment, when bovine teeth are treated in carbamide peroxide (15%) and water vapor (0.2 to 1%). The brightness of whitening teeth was increased up to 2 times longer in the CIE chromaticity coordinates. The colorimetric spectrometer (CM-3500d) can measure color degree of whitening effect.