• Journal of Photoscience
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• 제6권3호
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• pp.91-96
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• 1999

Zeolites and microporouos materials continue to attract attention as novel hosts for photochemical reactions. Zeolities are attractive because of their ability to selectivity exchange and incorporate species within the void spaces and interconnecting channels, providing a spatial arrangement of molecules. Our research has primarily focused on intrazeolitic electron transfer from excited Ru(bpy)32+ in supercages of zeolite Y to a series of bipyridinium ions. In the Ru(bpy)32+ viologen-zeolite Y samples, the slowing of the back electron transfer from the bipyridinium radical cation to Ru(bpy)32+ allows for charge propagation via self exchange between diquat molecules. This provides an opportunity for permanent charge separation. When the migrating charge on the diquat radical within the zeolite reaches the surface, it can be transferred to a neutral viologen (PVS) in solution, resulting in permanent charge separation. The advantage of long-lived charge separation can be exploited for useful chemistry if suitable catablysts can be assembled on the zeolities. We have studied Ru(bpy)2 as water oxdiation catalysts. We have demonstrated that synthesis of RuO2 fibers on a zeolite via thermal decomposition of Ru3(CO)12 leads to the most active water decomposition catalyst reported to date. Because of the extensive interest of photochemical water reduction to H2, much is known about catalytic systems usin gone electron catalyst, and even more importantly, that no reaction of viologen occurred with H2 over this catalyst. The present challenge is to incorporate all these elements of the system into an architecture and we are examining zeolite membranes for this purpose.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.743-748
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• 1994

Photochemical reactions of saccharin with tertiary amines were explored. Saccharin was found to undergo an acid-base reaction with N-trimethylsilylmethyl-N,N-diethyl amine to form N-trimethylsilylmethyl-N,N-diethyl ammonium saccharin salt which is in equilibrium with free saccharin and N-trimethylsilylmethyl-N,N-diethyl amine insolution. Photoreaction of N-trimethylsilylmethyl-N,N-diethyl ammonium saccharin in $CH_3OH\;or\;CH_3CN$ results in the generation of desilylmethylated product, N,N-diethyl ammonium saccharin mainly along with benzamide. Photoreaction of N-methylsaccharin with N-trimethylsilylmethyl-N,N-diethyl amine in $CH_3OH$ leads to the production of o-(N-methylcarbamoyl)-N-ethylbenzenesulfonamid e as the major product along with N-methylbenzamide as the minor product. On the other hand, photoreaction of N,N,N-triethyl ammonium saccharin, generated from saccharin and triethylamine, produces N-methylbenzamide as the exclusive product. These photoreactions are quenched by oxygen indicating that triplets of saccharin and N-methylsaccharin are the reactive excited states. Based on the consideration of the redox potentials of saccharin and N-trimethylsilylmethyl-N,N-diethyl amine, and the nature of photoproducts, pathways involving initial triplet state single electron transfer are proposed for photoreactions of the saccharins with the ${\alpha}$-silylamine.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권3호
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• pp.234-238
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• 2002

구강악안면외과 영역의 전암병소와 종양의 치료를 위하여 국소적으로 ALA, 전신적으로 Forscan의 광감각제를 도포하거나 주입하여 기능적, 심미적으로 좋은 결과를 얻을 수 있었다. 아직 장기적인 추적조사가 요구되지만 광역학 요법은 기존의 수술법, 항암요법, 방사선치료와 함께 종양의 새로운 치료방법으로 이용될 수 있을 것으로 사료된다.

• 한국입자에어로졸학회지
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• 제4권1호
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• pp.9-20
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• 2008

The effect of light intensity on the ozone formation and the aerosol number concentration during the photochemical reactions of ambient air was investigated in an indoor smog chamber. The smog chamber consists of a housing, 64 blacklights, and a $2.5-m^3$ reaction bag made of Teflon film. The bag was filled with the unfiltered ambient air in Seoul from January 10 to March 18, 2002. In this work, the photolysis rate of $NO_2$, $k_1$ was used as an index of light intensity. Three levels of light intensity were controlled by changing the number of blacklights turned on among 64 blacklights: $0.29min^{-1}$ (50%), $0.44min^{-1}$ (75%), $0.57min^{-1}$ (100%). The ozone concentration increased rapidly within 10 minutes after irradiation irrespective of light intensity, thereafter it increased linearly during the irradiation. The ozone production rate seems to be dependent on both the light intensity and the quality of ambient air introduced into the reaction bag. The change in aerosol number concentration also depended on both the light intensity and the ambient air quality, especially aerosol size distribution. Based on the initial ambient aerosol size distributions, the photochemical potential for aerosol formation and growth is classified into two cases. One is the case showing aerosol formation and growth processes, and the other is the case showing no apparent change in particle size distribution.

• Journal of Photoscience
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• 제9권2호
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• pp.382-384
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• 2002

When illuminated with strong visible light, the reaction center Dl protein of photo system II is photodamage and degraded. Reactive oxygen species and endogenous cationic radicals generated by photochemical reactions are the cause of the damage to the Dl protein. Recently we found that the photodamaged Dl protein cross-links with the surrounding polypeptides such as D2 and CP43 in photosystem II. As the cross-linking reaction is dependent on the presence of oxygen, reactive oxygen species are suggested to be involved. Among the reactive oxygen species examined, ？ OH was most effective in the formation of the cross-linked products. These results indicate that the cross-linking is mostly due to ？ OH generated at photosystem II. The cross-linking site of the Dl protein is not known. As several tyrosine residues exist at the D­E loop of the Dl protein, there is a possibility that di-Tyr is formed between the D­E loop of the Dl protein and surrounding polypeptides during the strong illumination. Therefore, we examined the formation of di-Tyr using the monoclonal antibody against di-Tyr under excess illumination of the photosystem II membranes. The results obtained here suggest that no di-Tyr is formed during the excess illumination of photosystem II.

• 한국농림기상학회지
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• 제16권1호
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• pp.22-28
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• 2014

지구온난화와 같은 기후변화에 적응력이 높은 조림수종을 탐색하는 연구의 일환으로 $CO_2$농도 및 기온상승이 현사시나무의 광합성생리에 미치는 영향을 조사하였다. 그 결과 현사시나무는 $CO_2$농도 및 기온 상승에 의해서 줄기의 신장생장이 억제되고 광합성 능력이 저하되었다. 그리고 광합성능력과 관련된 색소(엽록소a, b, 카로티노이드)의 함량이 감소하였다. 특히 탄소고정계의 활성과 관련된 엽록소a의 감소가 현저하게 나타났다. 그리고 광-광합성곡선과 A-Ci곡선에서 광화학계의 활성을 나타내는 순양자수율이 7%, 전자전달속도가 14% 감소하고, 탄소고정계의 활성을 나타내는 탄소고정효율이 52%, 재인산화속도가 24% 감소하였다. 이러한 결과로 $CO_2$농도 및 기온 상승에 의한 현사시나무의 광합성능력 저하는 광화학계 및 탄소고정계의 활성저하에 기인하나, 탄소고정계의 활성저하가 더 크게 작용하였음을 알 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1535-1537
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• 1999

Photochemical defluorination and substitution of fluorocarbon-resin surfaces using a pulsed Nd:YAG laser(266 nm) and copper-sulfate$(CuSO_4)$ aqueous solution were discussed. Interface of copper nuclei and fluorocabon-resin was chemically bonded through oxygen which was photodissociated from water in copper-sulfate aqueous solution under the laser irradiation. The reaction mechanism for chemical surface modification is discussed on the basis of x-ray photoelectron spectroscopy and atomic force microscope analyses.

• 한국세라믹학회지
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• 제43권1호
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• pp.28-32
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• 2006

Diarylethene in photochromic materials was doped in organic-inorganic hybrid low-melting glasses were synthesized through a nonaqueous acid-base reaction process, which consists of network units including a small number of bridging oxides. The organic phase is a dichlorodimethylsilane while the inorganic phase is a tin(II) chloride. Diarylethene was incorporated into the glasses without any degradation of its functionality. The open form of diarylenthene, which is converted from the opening one upon UV-irradiation, is change to the closed form visible light-irradiation. The rate constant of the photochemical reaction is $31.78\times10^{-3}s^{-1}$ with 400 W UV lamp irradiation.

• Journal of Photoscience
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• 제1권2호
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• pp.89-94
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• 1994

The reaction of decaborane with trimethylsilyldiazomethane gives 1, 2-bis (trimethylsilyl)-1, 2-carba-closo-dodecaborane(12). This compound is similar to the icosahedral cage structure of o-carborane. This formation of the first adduct proceeds through deprotonation of the acidic center of B(9) and B(6) by intermolecular attack by the lone electron pair of the carbene, : CHSiMe$_3$. The yield of product is influenced by irradiation and thermal conditions.

• 대한화학회지
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• 제42권2호
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• pp.203-208
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• 1998

할로겐화아렌이 다른 아렌에 etheral alkyl그룹에 의해 연결된 2-halobenzyl phenyl ether( 1과 2)를 합성하여 제조적인 광반응에서 생성물을 확인하고 또 속도론적 광반응에서 그 반응성을 시험하였다. 질소 기류 하에서 2-chlorobenzyl phenyl ether(1)은 페놀과 photo-Fries형 생성물이 나왔으며 Br치환 ether2는 페놀과 photo-Fries형 생성물 이외에 광고리화 및 광환원 생성물이 나왔다. 이것은 Cl이 benzyl고리에 강하게 붙어 있기 때문에 상대적으로 약한 $CH_{2}-O$결합의 파열이 생긴 결과이다. 또 Br유도체 2는 phenyl-bromine 사이의 결합이 phenyl-chlorine사이의 결합보다 약하니까 결국 그 결합의 광유발 파열이 $CH_{2}-O$결합 파열과 경쟁적으로 되었음이 분명하다. 산소 존재하에서 페놀의 생성은 큰 변화가 없고, photo-Fries형 생성물은 약간 감소하고 , 그리고 광고리화 생성물과 광환원 생성물은 큰 영향을 받는 것으로 보아 광고리화와 환원반응은 삼중상태가 상관하고 photo-fries형 반응은 단일상태와 삼중상태가 동시에 상관하는 것이다.