• Journal of the Korean earth science society
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• v.25 no.6
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• pp.484-494
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• 2004

The Soowang Au-Ag deposits occur as quartz veins which filled fissures in middle Cretaceous porphyritic granite an/or gneiss of the Precambrian Sobaegsan gneiss complex. The paragenetic studies suggest that vein filling can be divided into four identifiable stages (I to IV). Stage I is the main sulfide stage, characterized by the deposition of base-metal sulfide and minor electrum. Stage II is the electrum stage, whereas stage III represents a period of the deposition of silver-bearing sulfosalts and minor electrum. Stage IV is the post ore stage. Mineralogical and fluid inclusion evidences suggest that mineralization of the Soowang deposits were deposited by the cooling of the fluids from initial high temperatures 300$^{\circ}C$ to later low temperatures 150$^{\circ}C$. The salinity of the fluids were moderate, ranging from 10.4wt.% equivalent NaCl in sphalerite to 3.1wt.% equivalent NaCl in barite. The gold-silver mineralization of the Soowang mine occurred at temperatures between 140 and 250$^{\circ}C$ from fluids with log $fs_2$ from -12 to -18 atm. A consideration of the pressure regime during ore deposition, based on the fluid inclusion evidence of boiling, suggests lithostatic pressure of less than 210 bars. This pressure condition indicates that vein system of the Soowang deposit formed at depth around 800 m below the surface at the time of gold-silver mineralization.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.279-292
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• 2015

New occurrences of large-scaled Zn-Pb deposits are recently found in the Danjang-myeon, Milyang. They are skarn-type deposits which replaced the intercalated limestone beds in the Jeonggaksan Formation. This study aims at characterizing occurrences, mineralogy, and chemistry of Zn-Pb ores and skarn minerals. Skarn orebodies are mainly found in 3 areas, named Gukjeon-ri, Gorye-ri, and Gucheon-ri orebodies, where sphalerite found as main ore mineral in 200-300 m in height and amount of galena increases as altitude does. Ores are dark grey to dark green in color and closely related with clinopyroxene zone. They occur with hedenbergite, grossular, actinolite, epidote, and small amounts of axinite, calcite, and quartz. Main ore mineral is sphalerite which includes tiny spotted grains of galena and chalcopyrite and becomes rich in grade in association with clinopyroxene and epidote. FeS contents in sphalerite show relatively wide range between 1.53 and 23.07 mole%, whose contents intend to increase towards biotite granite known as ore-related igneous rocks. CdS contents are in the range of 0.22-0.93 mole%, showing decrease tendency from southwest (Gukjeon-ri) to northeast (Gucheon-ri). Zn-Pb deposits developed in Danjang-myeon reveal decrease in temperature with increase of altitude, leading to gradual changes in compositions of ore and skarn minerals.

• Economic and Environmental Geology
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• v.22 no.3
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• pp.253-266
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• 1989

The Cu-Pb-Zn-Ag hydrothermal vein type deposits which comprise the Dongil and Dong-cheogogsan mines occur within the Cretaceous sedimentary rocks in the Euiseong Basin of the southern Korean peninsula. The ore mineralization is contained within three stage(I,II and III) quartz and calcite veins. Ore minerals occur as dominant chalcopyrite, galena, sphalerite, tetrahedrite and Pb, Ag, Sb and Bi-bearing sulfosalts. Stage I ore minerals were deposited between $400^{\circ}C$ and $200^{\circ}C$ from the fluid with moderate salinities(7.0 to 4.5 eq. wt. % NaCl). Evidence of boiling suggests pressure of less than 150 bars during stage I mineralization. This pressure corresponds to maximum depths of 650 m and 1700 m, respectively, assuming lithostatic and hydrostatic loads. The data on mineralogy, temperature and salinity, together with information on the solubility of Cu complex, suggest that Cu deposition is a result of boiling coupled with declining temperature from $350^{\circ}$ to $250^{\circ}C$ or declining log $a_{o_2}$(from -29.8 to -35.9 atm.)and increasing in pH. Pb, Ag, Sb and Bi-bearing sulfosalts were deposited by cooling and dilution at temperature of less than $250^{\circ}C$ from the ore fluid with less than -35.9 atm. of log $a_{o_2}$.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.526-536
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• 2009

The aim of this vitro-study is to evaluate the effects of fluoride on remineralization of artificial dentine caries. 10 sound permanent premolars, which were extracted for orthodontic reason within 1 week. were used for this study. Artificial dentine caries was created by using a partially saturated buffer solution for 2 days with grounded thin specimens and fractured whole-body specimens. Remineralization solutions with three different fluoride concentration (1 ppm. 2 ppm and 4 ppm) were used on demineralized-specimens for 7 days. Polarizing microscope and scanning electron microscope were used for the evaluation of the mineral distribution profile and morphology of crystallites of hydroxyapatite. The results were as follows: 1. When treated with the fluoride solutions, the demineralized dentine specimens showed remineralization of the upper part and demineralization of the lower part of the lesion body simultaneously. 2. As the concentration of fluoride increased, the mineral precipitation in the caries dentine increased. The mineral precipitation mainly occurred in the surface layer in 1 and 2 ppm- specimens and in the whole lesion body in 4 ppm -specimens. 3. When treated with the fluoride solution, the hydroxyapatite crystals grew. This crystal growth was even observed in the lower part of the lesion body which had shown the loss of mineral.

• The Korean Journal of Food And Nutrition
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• v.11 no.3
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• pp.267-271
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• 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 Hydrogen and New Energy
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• v.18 no.2
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• pp.197-206
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• 2007

There are several methods for the hydrogen production such as steam reforming of natural gas, photochemical method, biological method, electrolysis and thermochemical method, etc. Many researches have been widely performed for the hydrogen production method having low production cost and high efficiency. In this paper, the patents concerning the photochemical hydrogen production method were gathered and analyzed. The search range was limited in the open patents of USA(US), European Union(EP), Japan(JP), and Korea(KR) from 1996 to 2005. Patents were gathered by using key-words searching and filtered by filtering criteria. The patent application trend was analyzed by the years, countries, companies, and technologies.

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

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.731-744
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• 2017

Triplet-triplet annihilation upconversion (TTA-UC) is a special photochemical process that converts low energy photons to higher energy photon via combination of organic chemicals which fulfill specific energetic criteria. TTA-UC has been known as attractive technology that is able to enhance energy conversion efficiency of the photonic devices based on sunlight, which is achieved by conversion of wasted low energy photons in solar spectrum into higher energy photon. In the present paper, we introduced the photochemical mechanism and characteristics of TTA-UC phenomenon, which is yet unfamiliar to the domestic academia, and investigated recent research status, application, and future research directions of TTA-UC technology.

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.273-280
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• 1969

The MO's of maleic anhydride are calculated using the parameter values, $h_{o}$.= 1, $h_{o}$:= 2, $k_{c=o}$= 1, $k_{c-o}$= 0.8, and ${\delta}_{{\alpha}_n}=2{\times}(0.3)^n$. With these MO's the interaction energies of the photochemical reaction of maleic anhydride (MA) with benzene are calculated using intermolecular orbital theory. It is shown that there are cases where the interaction energy includes a constant term and this term takes a great role in the photochemical interaction energy, and that with the calculated interaction energies the reaction mechanism is quite well explained. And it is proved that the photochemical reaction is possible for the second addition step of MA to benzene, and that the MA-benzene adduct should have the well-known stereochemical structure.

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.153-158
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• 1998

백금족 원소의 광화 마그마 내에서의 지화학적·결정학적 거동을 밝히기 위하여 백금, 안티모니, 테루리움계를 선택하여 800℃에서 안정한 광물 또는 화합물의 종류와 이들의 공생군, 원소간의 고용한계 등에 대해 실험적으로 연구하였다. 순도가 높은 각 원소를 초기 반응 물질로 하였으며, 고순도 석영관을 용기로 사용하였으며, 화학 반응 생성물은 반사현미경의, X선회절분석기, 전자현미분석기 등을 사용하여 분석하였다. 800℃에서 안정한 화합물로는, 백금(Pt), PtSb(stumpflite), PtSb2(geversite), PtTe, Pt3Te4, Pt2Te3, PtTe2(moncheite)이다. 이 연구 결과로부터 800℃에서의 상평형다이아그램을 정립하였다. 이 온도에서는 stumpflite와 geversite 및 moncheite가 현저히 치환고용체를 이루는데 그 한계는 각각 10 at.% Te, 28.5 at.% Te, 19.5 at.% Sb이다. 특히 원소광물인 백금과 stumpflite 및 moncheite는 화학성분은 이들 광물을 포함하고 있는 광상의 생성온도를 제시해 주는 지질온도계 역할을 할 수 있다.