• 한국환경과학회지
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• 제14권2호
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• pp.231-240
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• 2005

The number of cases exceeding environmental standards of atmospheric ozone in the major cities in Korea has steadily increased during the past decades. In order to understand and analyze the atmospheric reactions in the atmosphere, especially the secondary photochemical reactions, smog chambers studies have been performed very actively by many research groups worldwide. However, these studies have focused on the mechanism of photochemical reactions in high concentration conditions, not at the ambient levels. Therefore, in-depth studies in these conditions are essentially needed to realize exact mechanism in the atmosphere near the earth surface, especially at Korean atmospheric conditions. In this experiment, the mechanism of photochemical smog was examined through a comparative experiment of smog chambers under sun light and black light conditions. The results of our study indicated that concentrations of ozone, aldehyde, and PAN increased as the radiation of light source increases. Photochemical reaction patterns can be considered quite similar for both black light and sun light experiments. Based on our experiments using toluene as a reactant which is present at significant high levels in ambient air relative to other VOCs, it was found that toluene could contribute notably to oxidize NO to $NO_2$, this reaction can eventually generate some other photochemical oxidants such as ozone, aldehyde, and PAN. The results of simulation and experiments generally showed a good agreement quite well except for the case of $O_3$. The restriction of oxidization of NO to $NO_2$ seems to cause this difference, which is mainly from the reaction of peroxy radical itself and other reactants in the real gas.

• 한국환경농학회지
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• 제2권2호
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• pp.103-107
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• 1983

생활탄(生活炭) 및 이산화(二酸化)망강필타로 공기(空氣)를 로과(瀘過)한 정화실(淨化室)과 공기(空氣)를 그대로 송입(送入)한 비정화실(非淨化室)로 구분(區分)하여 재배(栽培)한 수도(水稻)에 대(對)한 photochemical oxidants 피해발생(被害發生)은 공기정화실(空氣淨化室)에서 생육(生育)한 수도(水稻)에는 인정(認定)되지 않았으나 비정화실(非淨化室)에서는 10pphm 이상(以上)의 photochemical oxidants가 발생(發生)한 다음날에 2회(回) 가시피해증상(可視被害症狀)이 관찰(觀察)되었다. 공기정화실(空氣淨化室)의 수도(水稻) 생육양(生育量)은 지상부(地上部) 및 근부(根部) 모두 비정화실(非淨化室)보다 증가(增加)하였으며 특(特)히 근부(根部)의 생육량(生育量) 증가(增加)가 현저(顯著)하였다. 식물(植物)의 기공개폐(氣孔開閉)와 밀접(密接)한 관계(關係)가 있는 ABA 함량(含量)은 비정화실(非淨化室)의 수도(水稻)가 정화실(淨化室)의 수도(水稻)보다 높아 photochemical oxidants에 의(依)하여 식물체내(植物體內) ABA 함량(含量)이 증가(增加)되었다. 외기(外氣)를 정화(淨化)하므로서 근활력(根活力)이 현저(顯著)히 증가(增加)하여 photochemical oxidants 피해(被害)에 의(依)하여 근활력(根活力)이 현저(顯著)히 감소(減少)하는 것이 확인(確認)되었다.

• 한국환경과학회지
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• 제15권3호
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• pp.203-209
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• 2006

In predicting oxidants concentration, the most important fact is to select a suitable photochemical reaction mechanism. Sensitivity analysis of $O_3$ and other important photochemical oxidants concentrations was conducted by using CBM-IV model. The predicted oxidants concentration was considerably related with the initial concentration of formaldehyde, $[NO_2]/[NO],\;NO_x$, RH and RCHO. As the initial concentration of formaldehyde increased, concentration of $NO_2$ increased. $O_3$ concentration was proportional to the $[NO_2]/[NO]$ ratio. When the initial concentrations of RH and RCHO were high, photochemical reaction was more reactive, including more rapid conversion of NO to $NO_2$ and increased oxidants. Also, the sensitivities of ozone formation to rate constants, $K_l,\;K_2\;and\;K_3$ in the $NO_2$ photolysis were studied.

• 한국환경과학회지
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• 제1권1호
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• pp.19-33
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• 1992

The high oxidants, which occur the daily maximum concentrations in the afternoon, are transported into the other region via long range transport mechanisms or trapped within the shallow mixing boundary layer and then removed physically (deposition, transport by mountain wind, etc.) and chemically (reaction with local sources). Therefore, modeling formation of photochemical oxidants requires a complex description of both chemical and meteorolog ital processecs . In this study, as a part of air quality studies, we reviewed various aspects of photochemical modeling on the basis of currently available literature. The result of the review shows that the model is based on a set of coupled continuity equations describing advection, diffusion, transport, deposition, chemistry, emission. Also photochemical oxidant models require a large amount of input data concerned with all aspects of the ozone life cycle. First, emission inventories of hydrocarbon and nitrogen oxides, with appropriate spatial and temporal resolution. Second, chemical and photochemical data allowing the quantitative description of the formation of ozone and other photochemically-generated secondary pollutants. Third, dry deposition mechanisms particularly for ozone, PAN and hydrogen peroxide to account for their removal by absorption on the ground, crops, natural vegetation, man-made and water surfaces. Finally, meteorological data describing the transport of primary pollutants away from their sources and of secondary pollutants towards the sensitive receptors where environmental damage may occur. In order to improve our present study, shortcomings and limitation of existing models are pointed out and verification Process through observation is emphasized.

• Journal of Photoscience
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• 제7권1호
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• pp.15-19
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• 2000

The photochemical reaction mechanism has been investigated for methanol insertion into the p-substituted phenylketo carbenes. The triplet spin state of phenyl koto carbene is stabilized by the neighbored carbonyl electrons. When the phenylketo carbene reacts with methanol, the ylied intermediate is formed, then moves to the activated transition state.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.423-425
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• 2008

In this paper, We have designed and manufactured a photochemical reaction lamp type ozonizer system which was applied to keep quality of herb medicines during storage. We used photochemical reaction lamp in a storage system, and investigated the sterilization characteristic. Also, we made research an ingredient and quality characteristic of herb medicines according to ozone storage.

• Archives of Pharmacal Research
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• 제3권2호
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• pp.87-88
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• 1980

The goal of this research is to provide information that will lead to the development of new non-phototoxic antimalarial compounds. The goal was approached by first learning the chemical mechanism of phototoxicity of six representative compounds 1a-f: a[(diethyl-, -dihexyl-, and -dioctyl- aminomethyl)]-2-(3', 4' -dichlorophenyl)-6-methoxy-4-quinolinemethanol (1a, 1b, and 1c) and .alpha. [(diethyl-, -dibutyl-, and -dihexyl-aminomethyl)]-2-(-4'-methoxyphenyl-6-methoxy-7-chloro-4-quinolinemethan ol (1d, 1e, and 1f). The photochemical reaction of these compounds was investigated in 2-propanol. Similar photochemical fragmentation reactions accurred in all compounds.

• Bulletin of the Korean Chemical Society
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• 제12권1호
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• pp.57-60
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• 1991

Benzosilacyclobutenes were prepared from the reactions of 1,1-dichlorobenzosilacyclobutene with Grignard reagents or t-butyllithium. In the thermal reactions with alcohols, benzosilacyclobutenes underwent both benzyl-silicon and aryl-silicon bond rupture to yield (dialkyl)alkoxy-o-tolylsilanes and (dialkyl)alkoxybenzylsilanes, respectively. The photochemical reactions, however, produced only the former products via o-silaquinone methides.

• Journal of Photoscience
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• 제1권1호
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• pp.67-68
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• 1994

INTRODUCTION : The photochemistry of nitro chromophore has been the subject of intense study only in recent years. Unlike the carbonyl functional group, of which the photochemistry has been quite extensively studied and fairly well understood, as a result of excellent work done by numerous physical and organic photochemists alike, the nature of photochemistry of nitro group has only recently been systematically explored. The photochemistry of nitro group exhibits general features of the photochemistry of the carbonyl groups such as hydrogen abstraction by the diradical species generated from the n-$\pi$$^*$ excited state of the nitro group. Other photochemical pathways common to the carbonyl group such as the biradical intermidiate formation, photocycloelimination, and cydoaddition reactions are also open for the nitro group. Of all the photochemical reactions of the nitro group mentioned above, hydrogen abstraction by the n-$\pi$$^*$ excited state of the nitro group has drawn much attention by synthetic organic chemists and polymer chemists. In the field of organic synthesis, above mintioned photochemical reaction has been utilized in the photoprotection-deprotection chemistry.

• 한국대기환경학회지
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• 제9권3호
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• pp.183-190
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• 1993

For the efficient control of photochemical smog materials, the researches on the change patterns of photochemical smog precursors are indispensable. In this study, a time-series analysis was performed for the auto-monitoring data of Kwanghwamun and Jamsil stations in 1990, and the change patterns of photochemical smog materials were studied. Especially, auto-correlation coefficients were analyzed to investigate the cyclic characteristics of pollutants in question and cross-correlation coefficients to investigate the correlations between pollutants adjusted for time lag and between $O_3$ and meteorological factors. Results of researches are as follows: First, in the case of NO and $NO_2$ intimately related to human activities, 12-hour cycle was prevalent. But $O_3$ showed 24-hour cycle. Second, NO showed a relatively high correlation with $O_3$ and usually developed into $O_3$ 5 to 7 hours later. Third, temperature, insolation intensity, and wind speed showed a positive correlation with $O_3$ while relative humidity a negative correlation.