• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.4 s.193
• /
• pp.147-152
• /
• 2007

UV laser ablation of polyimide is a combination of photochemical and photothermal mechanism. Photochemical mechanism is that molecular bonds are broken by photon energy and photothermal is evaporation and melt expulsion. When the laser processing, the etching depth needs to be calculated for prediction of processing result. In this paper, in order to predict the laser etching depth of polyimide by UV laser with the wavelength of 355nm, the theoretical model which includes both the photothermal and the photochemical effect was introduced. The model parameters were obtained by comparing with experimental results. The 3rd harmonic $Nd:YVO_4$ laser system was used in the experiment. From these experimental and theoretical results, the laser ablation of a polyimide was verified to achieve the highest quality microstructure.

• Journal of the Korean Chemical Society
• /
• v.21 no.2
• /
• pp.102-107
• /
• 1977

Photochemical reduction of 1,2-bispyrazylethylene,a stilbene like heterocompound, was studied in hydrogen donating solvents and reduction product, 1, 2-bispyrazylethane, was identified. Salt and solvent effects on the quantum yields of the reduction, sensitization and quenching studies showed that the reactive state for the photochemical reduction of the compound is $(n,{\pi}^*)^1$ state rather than $({\pi},{\pi}^*)^1$ state.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2005.11a
• /
• pp.84-85
• /
• 2005

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.37 no.3
• /
• pp.227-236
• /
• 2011

The new sunscreen agent, methoxycinnamidopropyl polysilsesquioxane, is manufactured as polymeric particles with an organic/inorganic hybrid composition. We have already reported the manufacturing method, physical properties, and sunprotection effects of methoxycinnamidopropyl polysilsesquioxane. In this study, we evaluated the photochemical properties and photostabilities of methoxycinnamidopropyl polysilsesquioxane that has the same functional group as a typical organic sunscreen agent, ethylhexyl methoxycinnamate (EHMC). Using the correlation of UV absorbance and fluorescence, we studied photostabilizers to enhance the photostability of methoxycinnamidopropyl polysilsesquioxane. Finally, we confirmed that octocrylene, ethylhexyl methoxycrylene, and bis-ethylhexyloxyphenol methoxyphenyl triazine were good photostabilizers for methoxycinnamidopropyl polysilsesquioxane.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2003.10a
• /
• pp.132-133
• /
• 2003

• Korean Journal of Environmental Biology
• /
• v.34 no.3
• /
• pp.161-168
• /
• 2016

In this study, growth enhancing effect of hatchery waste egg decomposed liquid fertilizer in pepper plant cultivation through chlorophyll fluorescence (O-J-I-P) analysis. In a whole growth period, egg decomposed fertilizer treated pepper grew well than non treated plant, though it was not statistically significantly different. Amount of chlorophyll fluorescence of non treated plant was higher thant that of fertilizer treated plant. It is determined that eventually lead to increased photosynthesis. In this study, six parameters, Fo, ABS/RC, RC/ABS, TRo/RC, DI0/RC, and DF Total ABS were the important factors represent efficiency of photochemical responses of pepper plant treated with hatchery waste egg decomposed fertilizer.

• The Korean Journal of Food And Nutrition
• /
• v.11 no.3
• /
• pp.267-271
• /
• 1998

The photochemical carcinogenic reaction mechanism and molecular carcinogenic intensity through the reaction of dibromo carbene and diazomethane with dehydroacetic acid and coumarin have been studied under the two kinds of photolysis. The reaction intensities show the degree of carcinogenic activity. Under the condition of UV/vis light source, the yield of high toxic carcinogenetic carbene intermediate is produced less than those of the laser flash photolysis.

• Journal of the Korean Vacuum Society
• /
• v.20 no.4
• /
• pp.300-306
• /
• 2011

We report the surface distribution of metal (Ag, Au) nanoparticles grown on polarity-patterned ferroelectric substrates by photochemical reaction. Single crystal periodically polarity-patterned $LiNbO_3$(PPLN) was used as a ferroelectric substrate. The nanoparticles were grown by ultra-violet (UV) light exposure of the PPLN in the aqueous solutions including metas. The surface distribution of the grown nanoparticles were measured by atomic force microscopy and identification of the orientation of the polarity of the ferroelectric surface was performed by piezoelectric force microscopy. The Ag- and Au-nanoparticles grown on +z polarity regions are larger and denser than that on -z polarity regions. In particlur, the largest and denser Ag-nanoparticles were grwon on the polarity boundary regions of the PPLN while Au-nanoparticles were not specifically grown on the boundary regions. Thus, we found that the size and position of metal nanoparticles grown on ferroelectric surfaces can be controlled by UV-exposure time and polarity pattern structures. Also, we discuss the difference of the surface distribution of the metal nano-particles depending on the polarity of the ferroelectric surfaces in terms of surface band structures, reduced work fucntion, and inhomogeneous electric field distribution.

• Applied Biological Chemistry
• /
• v.45 no.4
• /
• pp.218-222
• /
• 2002

Lycii Cordex Radicis extract (gigolpi) examined through SOS Chromotest showed a strong, dose-dependent antimutagenic effect on the tert-butyl hydroperoxide (t-BOOH) induced mutagenecity. Gigolpi revealed considerable superoxide anion radical scavenging activity under L-ascorbic $acid-CuSO_4$ system, but showed lower hydroxyl radical scavenging activity in photochemical test system. Hot-water gigolpi extract delayed protein oxidation, whereas lipid peroxidation of rat skin exposed to UVB radiation was inhibited. The results indicate that gigolpi possessing antioxidant activity against UVB-induced lipid peroxidation could be used as a raw ingredient for manufacturing functional cosmetics

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2008.11a
• /
• pp.93-93
• /
• 2008

니켈도금은 각종 소지 상에 직접적이고 밀착성이 양호하고, 변색이 적고 방청력이 크며, 경도, 내식성, 내마모성 및 유연성이 우수하다. 또한 최근 활발히 진행되고 있는 광촉매 연구에 $TiO_2$는 우수한 광화학적 안정성, 효과적인 전하분리, 높은 산화 환원력 및 상업적 적용성을 갖기 때문에 니켈도금용액에 $TiO_2$를 첨가하며 복합도금을 행함으로써 니켈이 가지고 있는 기존의 우수한 특성에 $TiO_2$의 광분해 효과를 부과시킴 으로써 그 특성이 한층 더 향상되는 것을 알수있다. 본 연구에서는 수용액전해질과 비수용액 전해질에서의 Ni-$TiO_2$ 복합도금의 특성을 비교 분석해보았다. 동전위(Potentiodynamic)실험 및 순환전위(Cyclic Voltammetry)실험을 하였으며, 도금층의 특성 및 두께는 OM,SEM을 이용하여 분석하였다. 또한 복합도금 촉매 전극에 의한 광분해 효과를 보기 위해서 UV램프를 이용하여 분석하였다.