• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.193-195
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• 2005

광화학측정이 이루어진 기간 중 일사량이 강한 날에 관측 오존의 농도와 광화학 모델의 광화학 정류상태로 추정된 오존의 농도는 아주 밀접한 근접성을 보였다. 광정류 상태로부터의 이탈 정도에 영향을 미치는 인자로는 측정 지역 근처에서의 지역적 NO$_{2}$ 생성원의 존재, 지역적 NO 또는 오존의 소멸, 비 정류상태 조건, 또는 측정의 오차 등에 기인한 것으로 추정된다. 오존의 생성 속도에 가장 크게 영향을 주는 화학반응은 NO와 HO$_{2}$의 화학반응으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.409.2-409
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• 2002

• Economic and Environmental Geology
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• v.55 no.1
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• pp.53-61
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• 2022

The Gasado Au-Ag deposit is located within the south-western margin of the Hanam-Jindo basin. The geology of the Gasado is composed of the late Cretaceous volcaniclastic sedimentary rocks and acidic or intermediate igneous rocks. Within the deposit area, there are a number of hydrothermal quartz and calcite veins, formed by narrow open space filling along subparallel fractures in the late Cretaceous volcaniclastic sedimentary rock. Vein mineralization at the Gasado is characterized by several textural varieties such as chalcedony, drusy, comb, bladed, crustiform and colloform. The textures have been used as exploring indicators of the epithermal deposit. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz veins; stage II, barren carbonate veins) considering major tectonic fracturing event. Stage I, at which the precipitation of Au-Ag bearing minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite and pyrrhotite with minor chalcopyrite, sphalerite and electrum; middle, characterized by introduction of electrum and base-metal sulfides with minor argentite; late, marked by argentite and native silver. Au-Ag-bearing mineralization at the Gasado deposit occurred under the condition between initial high temperatures (≥290℃) and later lower temperatures (≤130℃). Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur (≈10^-10.1 to ≤10^-18.5atm) by evolution of the Gasado hydrothermal system with increasing paragenetic time. The Gasado deposit may represents an epithermal gold-silver deposit which was formed near paleo-surface.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.7-12
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• 2005

When a light is projected upon a material, part of its radiant energy is absorbed and the rest is reflected or transmitted according to the nature of the material. The molecules of the substance absorbing a light obtains the radiant energy to make thermal reactions or photochemical reactions. Specially, photochemical reactions by ultraviolet(UV) radiation brings about photochemical degradation such as color change. Because the photochemical damage brings about a devaluation of material and once damaged, it is irretrievable, it is necessary to minimize the damage and conserve the native quality of a material by a protective lighting system. This paper presents the measurement and photochemical damage for UV radiation from light sources. We measured the optical radiations from artificial light sources and daylight, and we analyzed a functional relation between irradiance and UV radiation form the results.

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.1-7
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• 1999

Metal colloidal particles have been prepared by a photo-chemical process in an aqueous solution containing semiconductor nanocrystallites. Metal colloidal particles produced in CdS and AgBr exhibit different absorption spectra. Au particles produced in solution with CdS show typical Au plasmon resonance absorption spectra. On the other hand Ag particles in solution with AgBr shows surface plasmon resonance absorption spectra which are red-shifted, as compared to that of a dispersion of homogeneous Ag colloidal particles in the same host. The extent of red-shift depends on the UV illumination time. This phenomenon is interpreted within the context of effective medium theory for small volume fractions. From the theory, a metal coated particle predicts Ag plasmon resonance, red shifted with respect to 400 nm that would be associated with a silver particle in solution. The absorption peak position is very sensitive to the coating thickness.

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

• Economic and Environmental Geology
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• v.42 no.1
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• pp.1-8
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• 2009

The Haman mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Almost all occurrences in the Haman area are representative of copper-bearing polymetallic hydrothermal vein-type mineralization. Within the area are a number of fissure-filling hydrothermal veins which contain tourmaline, quartz and carbonates with Fe-oxide, base-metal sulfide and sulfosalt minerals. The Gunbuk, Jeilgunbuk and Haman mines are each located on such veins. The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage I, tourmaline + quartz + Fe-Cu ore mineralization; Stage II, quartz + sulfides + sulfosalts + carbonates; Stage III, barren calcite. Equilibrium thermodynamic data combined with mineral paragenesis indicate that copper minerals precipitated mainly within a temperature range of $350^{\circ}C$ to $250^{\circ}C$. During early mineralization at $350^{\circ}C$, significant amounts of copper ($10^3$ to $10^2\;ppm$) could be dissolved in weakly acid NaCl solutions. For late mineralization at $250^{\circ}C$, about $10^0$ to $10^{-1}\;ppm$ copper could be dissolved. Equilibrium thermodynamic interpretation indicates that the copper in the Haman-Gunbuk systems could have been transported as a chloride complex and the copper precipitation occurred as a result of cooling accompanied by changes in the geochemical environments ($fs_2$, $fo_2$, pH, etc.) resulting in decrease of solubility of copper chloride complexes.

• YAKHAK HOEJI
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• v.44 no.1
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• pp.36-40
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• 2000

The photodegradation of pefloxacin, photolabile fluoroquinolone antibacterial agent, was studied. In the presence of $N_2$, photodegradation of pefloxacin was suppressed. The singlet oxygen and free radical generated in the reaction media proceeded photochemical reaction. The photodegradation of peflxacin was sensitized by benzophenone, a triplet state sensitizer.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.259-260
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• 2007

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• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.170-172
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• 2007