• Rapid Communication in Photoscience
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• 제2권3호
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• pp.76-78
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• 2013

Photoaddition reactions of aromatic carbonyl compounds with silyl thioketene acetals have been explored. The results of this study show that the acetonphenone react with dimethyl substituted silyl thioketene acetal competitively via either single electron transfer (SET)-desilylation or [2+2]-cycloaddition pathways to produce b-hydroxyester and oxetanes. In contrast, photochemical reactions of the benzaldehyde with dimethyl substituted silyl thioketene acetal mainly lead to the formation of oxetanes arising by [2+2] cycloaddition. A comparison of the results with those of silyl ketene acetal revealed that replacement of sulfur atom in ${\alpha}$-silyl donor substrate bring about dramatic changes in chemoselectivities as well as excited state reaction mechanism.

• Journal of Photoscience
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• 제4권1호
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• pp.17-21
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• 1997

The photochemical reactions of the neat chloroform and the aqueous chloroform in the absence (saturated with argon) and presence of 02 (saturated with air or oxygen) have been investigated using 184.9 nm UV light. The irradiation of the deoxygenated neat chloroform causes the formation of hexachloroethane, pentachloroethane, and 1, 1, 2, 2-tetrachloroethane. The initial quantum yields of the products were determined to be 6.37 x 10$^{-4}$, 4.04 x 10$^{-4}$ and 1.76 x 10$^{-4}$, respectively. In the irradiation of aqueous chloroform, chloride ion was also formed along with the products listed above and 1, 1, 2, 2-tetrachloroethane was the predominant product among the chlorinated organic products, which contrasts to the case of the neat chloroform. The presence of oxygen during the irradiation of aqueous chloroform had an effect on the yield of the products. With increasing the concentration of oxygen, the formation of the products was decreased. Probable reaction mechanisms for the photochemical reaction were presented on the basis of products analysis.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 춘계학술대회 논문집
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• pp.362-363
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• 2003

Photochemical ozone is formed from nitrogen oxides (NOx) and volatile organic compounds(VOCs) through non-linear interactions between chemical reactions and meteorology, and the relationship between precursors and photochemical ozone will be changed to match the emission distribution and meteorological fields. It is generally known that for some conditions the process of ozone formation is controlled almost entirely by NOx and is largely independent of VOC, while for other conditions ozone production increases with increasing VOC and does not increase(or sometimes even decreases) with increasing NOx (omitted)

• Journal of Photoscience
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• 제2권2호
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• pp.77-81
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• 1995

Photoreactions of pseudosaccharin ethers have been investigated. Pseudosaccharin 3-allyl ether undergoes a facile photoreaction via reaction pathways involving homolysis of bond between pseudosaccharyl oxygen and 3-allyl carbon, and excited nucleophilic substitution of allyloxy group by solvent which are not quenched by oxygen present in the reaction. Product yield demonstrates that the homolysis pathway predominates over the nucleophilic substitution in ca. 7:1 ratio. In contrast, pseudosaccharin alkyl ethers follow different reaction routes to produce two products, solvent-substituted pseudosaccharin alkyl ethers and reduction products, 3-alkoxy-1, 2-benzisothiazoles. The formations of reduction products, 3-alkoxy-1, 2-benzisothiazoles are completely quenched by oxygen.

• Journal of Photoscience
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• 제9권2호
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• pp.1-4
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• 2002

Hula-twist is a volume-conserving photoisomerization reaction mechanism postulated in 1985 to account for the rapid photoisomerization of the retinyl chromophore in rhodopsin. The requisite stereochemical consequence of simultaneous isomerization of a double bond and an adjacent single bond has recently been demonstrated in isomerization of pre-vitamin D in an organic glass and by many other examples of organic systems already reported in the literature This paper reports the consequence in applying the mechanism to the primary photochemical process of several photosensitive biopigments: bilirubin, photoactive yellow protein, bacteriorhodopsin and rhodopsin. It is shown that the anchored nature of the chromophores must first be taken into consideration.

• Journal of Photoscience
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• 제9권1호
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• pp.5-7
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• 2002

Direct irradiation of carbonyl compounds such as some aldehydes, ketones and anthraquinone in N,N-dimethylamiline(DMA), without using other solvents, gave $\beta$-hydroxyamines as the major products. Irradiation of anthrone and DMA in methanol afforded ${\gamma}$-hydroxyamine. The structure of the photoproduct was confirmed by treatment with an acid to give a bicyclic compound.

• 한국광과학회:학술대회논문집
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• 한국광과학회 1999년도 학술대회지
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• pp.7-7
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• 1999

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2002년도 추계학술대회 논문집
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• pp.135-136
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• 2002

최근 들어, 대도시 지역에서 오존(O$_3$)농도가 환경기준을 초과하는 빈도가 증가함에 따라 대기 중 광화학 대기오염현상과 그에 따른 오존 등 2차 광화학 오염물질에 대해 많은 관심이 집중되고 있다. 이러한 복잡한 대기중의 반응을 이해하고 해석하기 위하여 Smog Chamber를 이용한 대기 중 광화학 반응 연구가 진행 중에 있으며, 국내에서도 연구가 이루어지고 있다 Smog Chamber를 통해 대기 중의 광화학 반응의 세부적인 이해와 수학적 모델에 필요한 화학반응들의 변수를 제공하는 등 포괄적이고 종합적인 연구를 수행할 수 있다. (중략)

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.867-870
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• 2007

In order to solve image sticking phenomena, the gas-phase and liquid-phase interfacial reactions of photosensitive polyimide can annihilate photoreactive carbon-carbon double bonds, which remain after photo-alignment process. The annihilation processes dramatically affect residual DC and photochemical reorientation of photoactive functional groups.

• Bulletin of the Korean Chemical Society
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• 제22권11호
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• pp.1207-1212
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• 2001

A new photochemically bifunctional epoxy and dimethacrylate compounds were synthesized for investigating the photosensitivity under UV irradiation. Photosensitivity of the synthesized chalcone-based compounds was investigated by using UV-visible absorption and Fourier transformed infrared (FT-IR) spectroscopies. The result of spectroscopic analysis substantiated that the two chalcone-based compounds have functions of both photocrosslinking and photopolymerization by UV exposure in the presence of photoinitiator. Two kinds of photochemical reactions proceeded competitively during UV exposure. Particularly, we studied the effect of photopolymerization on the rate of photocrosslink due to cycloaddition in the two oligomeric compounds.