• 에너지공학
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• 제14권2호
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• pp.133-139
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• 2005

도장공정에서 발생하는 VOC의 처리를 위한 활성탄-광촉매 복합시스템을 제안하였고, VOC제거성능을 실험적으로 평가하였다. 활성탄 합은 톨루엔 흡착특성에 근거하여 설계하였고, 광촉매 시스템은 $TiO_2/SiO_2$ 유동층 반응기와 $TiO_2$코팅된 필터의 연계시스템으로 설계하였다. 본 활성탄-광촉매 복합시스템은 서로 다른 VOC 화학종 및 농도에 따라 $75\~100\%$에 이르는 VOC제거효율을 보여주었다.

• 한국대기환경학회지
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• 제17권2호
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• pp.169-177
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• 2001

The concentrations of ambient volatile organic compounds (VOC) were investigated from the Kwangju area. A total number of sixty six sample were collected and analyzed during day/night periods from June to September 1999. Each of the canister sample ws analyzed for alkane and aromatic compounds using a GC/MSD sys-tem. The concentration of VOC in mean day/night time, when compared, was in the order: toluene(16%)> isobu-tane(14%)= acethylene(14%)> propane(12%)> ethane(11%)> butane(9%). The VOC concentrations were gene-rally higher during the daytime than the nighttime. The VOC with light weight(such as an alkane group, $C_2$-C(suh)5) showed generally higher concentrations during day/nighttime than the VOC with heavy weight (such as an aromatic group). High correlations were among the VOC emitted from the similar sources.

• 한국환경과학회지
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• 제24권10호
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• pp.1273-1283
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• 2015

In present study, the temporal characteristics of nine selected volatile organic compounds (VOCs), including four alcohol, 2 aldehyde, and 3 ketone compounds, in high-stories urban apartments over a 2-y period were investigated. The indoor VOC concentrations had generally a decreasing trend over the 2-y follow-up period. For examples, the 2E1H indoor concentration decreased from $10.8{\mu}g/m^3$ for the first two months to $5.1{\mu}g/m^3$ for the last two months. In addition, the DCA and ACT indoor concentrations decreased from 5.0 and $14{\mu}g/m^3$ for the first two months to 2.2 and $6.4{\mu}g/m^3$, respectively, for the last two months. The indoor-to outdoor concentration ratios over the 2-y period were much greater than 1, indicating that indoor VOC concentrations were higher than the outdoor VOC concentrations. Similar to those of the individual VOCs, the indoor-to-outdoor concentration ratios of all three VOC groups were higher than 1 over the 2-y follow-up period, suggesting higher indoor concentrations of the three VOC groups than outdoor concentrations. In consistence with the results of VOC indoor concentrations, the VOC emission rates decreased gradually as time passed, due to the decreased VOC emission strengths of indoor sources. Finally, there was an initial sharp decrease in the indoor VOC concentrations followed by a slower decrease, indicating a multi-exponential decay model for the target VOCs, which was demonstrated by comparison of the residuals and the adjusted coefficient of determination associated with the one and two-exponential fits of each data set.

• 환경위생공학
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• 제15권3호
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• pp.88-93
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• 2000

VOCs의 촉매산화 공정에서 다성분 VOCs 혼합물의 간섭효과와 독성저감에 고나해 연구를 수행하였다. VOCs로는 benzene, toluene, styrene을 선정하였고, 0.5% $Pt/{\gamma}-Al_2O_3$를 촉매로 사용하였다. 각 VOCs의 반응성은 치환기의 종류에 따라 결합력이 다르기 때문에 benzene > toluene > styrene의 순으로 완전산화 반응이 잘 진행되었다. VOCs의 혼합물의 경우 각 VOCs는 서로 억제제로 작용하여 오나전산화 전환율을 감소시켰는데 이는 촉매표면에 각각의 VOCs가 경쟁 흡착하기 때문으로 styrene > toluene > benzene의 순으로 간섭효과가 크게 나타나는 것을 확인할 수 있었다. 이성분계 혼합 VOCs의 경우 혼합비에 따른 완전산화 전환율은 간섭효과가 작은 VOCs의 경우 상대 VOCs의 농도가 작을수록 전환율이 크게 나타났으며, 간섭효과가 큰 VOCs의 경우에는 상대 VOCs의 농도에 관계없이 자신의 부분농도에 반비레하는 현상을 보였다. 따라서 VOCs의 독성저감 기술로 촉매산화공정을 추천할 수 있으며, 실제공정과 같은 혼합물의 경우에도 단일성분의 전환특성과 혼합물의 간섭효과로부터 공정조건을 예측할 수 있을 것으로 사료된다.

• 한국대기환경학회지
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• 제15권5호
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• pp.567-574
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• 1999

Volatile organic Compounds(VOC) were measured at an industrial site in Ulsan in 1997 and 1998. Twenty-four hour integrated ambient air samples were collected in 6 L SUMMA canisters during the periods of June 3 to 8, 1997 and June 12 to 17, 1998. The daily mean concentrations of the total $C_2-C_9$ VOC in 1998 were about one third of those in 1997. This decrease of VOC levels may be attributable to the measures to control the emissions of VOC and the decrease of the plant operation. The decrease in the concentrations of oxygenated hydrocarbons and alkenes, especially, contributed to the decrease of the total VOC concentrations in 1998. Lowever concentrations of alkenes compared to aromatics in 1998 were due to the decrease of ethylene and propylene. In the present study, methanol (12.0 ppb) was the most abundant species, followed by acetone (10.1 ppb), propane (6.0 ppb), and vinyl chloride (5.9 ppb). The total concentrations of hazardous air pollutants (HAPs) in 1998 were reduced compared to those in 1997. However, this decrease is due to the drastic decrease of the concentration of methanol. Except methanol, the concentrations of HAPs have not varied much. It is suspected that the VOC control strategy for the Ulsan industrial area has been successful for reducing the total VOC levels but might not be effective in reducing the concentrations of HAPs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.271.1-271.1
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• 2013

Titania is usually used in sun-screens, tooth paste, and other daily used objects as a pigment. However, scientists have focused on titania as photocatalyst due to its excellent activities. By fabricating vanadium doped TiO2 and CuOx co-catalyzed TiO2 nano-size filter, the degradation level of the volatile organic compound (VOC) concentration was tested using 365nm UV LED as light source in a closed chamber. Main purpose for this test is to evaluate the activities of various catalysts for degrading the VOCs which are detrimental to human body and toluene and p-xylene were chosen in the VOC removal test. Target gas materials were injected into the test chamber with dry air as carrier gas which was flowed into the gas washer bottle filled with liquid form of VOC substance. When the VOC gas flows into the chamber, it is circulated by 200 mm fan in order to contact with the set-up filter on the aluminum holder. Target gas concentration in the chamber was monitored using VOC detector (miniRae3000, Raesystems) which was also placed inside the chamber. With the measured concentration, the VOC degradation efficiency and the degradation rate were evaluated and used to compare the catalytic activities.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.755-761
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• 2015

광촉매의 VOC 제거 특성 평가에 관한 최근의 연구는 온도 변화가 거의 없는 상태에서 실시되었다. 온도 변화를 적게하기 위해 광량이 높은 UVLED를 챔버 위부에 배치하게 되면 광촉매와의 거리가 멀어져 그만큼 효율이 감소할 수 밖에 없으며 광촉매의 효율 향상을 위해서는 광원과 광촉매의 거리를 가까이 해야 할 필요가 있다. 본 연구에서는 UVLED 광원과 광촉매와의 거리를 가까이 두어 온도가 변하는 VOC 제거 시스템을 제작하였다. 광촉매로는 자외선 광원에서 반응하는 상용 $TiO_2$와 vanadium 이온을 도핑시킨 $TiO_2$를 사용하였으며 제작된 챔버를 이용하여 광촉매 효율을 평가하였다. VOC 제거 평가 시 테스트 전후 온도는 약 $20^{\circ}C$ 상승하여 UVLED 광원에 의해 변화된 온도로 VOC의 농도를 보정하여 온도에 따른 VOC 제거 효율 변화를 확인하였다. 보정 전후의 제거 효율을 비교하면 43~46%의 차이를 보였다. 챔버 내 온도 상승이 p-xylene의 농도 변화에 큰 영향을 주며 이를 보정하여 광촉매의 VOC 제거 효율을 평가할 필요가 있음을 확인할 수 있었다.

• Environmental Analysis Health and Toxicology
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• 제20권2호
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• pp.167-178
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• 2005

This study was carried out to evaluate the temporal, spatial, and seasonal variations of VOC, and to characterize the VOC concentrations in two large industrial complexes located in Pohang and Gumi cities. Twenty -four hours continuous sampling of selected VOC was made with STS 25 sequential tube samplers and double-bed adsorbent tubes. Air samples were collected every three hour interval for 7 consecutive days in each site during summer and winter. VOC were determined by thermal desorption coupled with GC/MS. A total of 27 VOCs of environmental concern were determined, including aliphatic, aromatic and halides. Generally. concentrations of toxic VOC were higher in Gumi than Pohang, and VOC levels in industrial areas were typically several-fold higher than those in residential areas. The most abundant VOC appeared to be toluene for both cities. However, chlorinated VOC were higher in Gumi than Pohang, while aromatic VOC were more abundant in Pohang than in Gumi. Two cities showed relatively different variations of VOC concentrations within a day. It is likely that traffic related sources are major factors affecting the VOC in Pohang, and industrial solvents usages are important sources in Gumi. These results imply that the occurrence and levels of atmospheric VOC are strongly dependent on the type of industries in each city. Therefore, in order to develop any control strategies or to establish the priority rankings for VOC in large industrial complexes, the type of industries and the occurrence of VOC in the atmosphere should be taken into consideration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.152-152
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• 2010

이종접합 태양전지에서 Intrinsic a-Si:H의 역할은 상당히 중요하다. Passivation 효과와 높은 Voc에 이르는 핵심적인 Layer이다. 본 연구는 Intrinsic a-Si:H Layer의 증착조건을 가변하여 최적의 Passivation 효과를 얻는데 목적이 있다. 웨이퍼는 n-Type $500\;{\mu}m$두께에를 사용하였다. Intrinsic a-Si:H Layer는 $SiH_4$ 가스와 $H_2$ 가스를 혼합하여 증착하게 되는데 혼합비는 1:5로 고정하였다. 증착두께는 이종접합 태양전지에서 필요한 5nm로 고정하였으며 증착장비는 PECVD를 이용하였다. PECVD는 VHF(60MHz)를 이용하였고 증착온도는 $200^{\circ}C$로 고정하여 진행하였다. 가변내용은 전극거리와 파워, 압력이다. 전극거리는 20mm에서 80mm까지 가변하였고 압력은 100mTorr에서 500mTorr까지 가변하였다. 파워는 플라즈마의 방정특성을 알아본 후 최소파워를 이용하여 증착하였다. 이는 증착 시 플라즈마에 의한 박막 손상을 최소화하기 위함이다. 측정은 QSSPC 방식으로 Carrier Lifetime과 Implied Voc를 측정하였으며 두께는 Ellipsometry를 이용하여 측정하였다. 전극거리 60mm에서 증착압력은 400mTorr이고 파워는 $14mW/cm^2$에서 가장 높은 Carrier Lifetime 과 Implied Voc를 나타내었다. Carrier Lifetime은 2.2ms이고 Implied Voc는 709mV를 달성 하였다. Carrier Lifetime이 높으면 Surface Recombination이 낮다는 의미이며 이는 고효율 이종접합 태양전지 제작에 있어서 직렬저항을 줄일 수 있는 필수적인 요소이다. Implied Voc는 이종접합 태양전지의 Voc에 직결된 인자로 이종접합 태양전지의 Voc를 예상할 수 있는 중요한 요소이다.

• 한국대기환경학회지
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• 제12권2호
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• pp.151-157
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• 1996

Vehicle occupant exposure to volatile organic compounds (VOCs) continues to be the subject of active research because of higher levels of VOCs in vehicles than in the surrounding ambient atmosphere and because of potential health risk. This study identified in-auto and in-bus exposures to 6 selected aromatic VOCs during rush-hour driving. A bus service route was selected to include an urban route (Taegu) and a suburban route (Hayang-Up) to satisfy the specified criteria of this study. The most abundant VOC concentration measured in this study was toluene. In-vehicle target Voc concentrations of the urban route were significantly different from those of the suburban segment. On the sum of average of the target VOCs, in-auto VOC concentration was about 1.5 times higher than in-bus VOC concentration. Based on the sum of average, in-automobile target VOC concentrations of this study were within the range of previous studies conducted in several cities of the United States, while in-bus VOC concentrations of this study were much lower than those of Taipei in Taiwan. In-vehicle VOC concentrations of present study significantly varied with sampling days, while they did not varied with driving period.