• Economic and Environmental Geology
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• v.35 no.3
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• pp.191-201
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• 2002

The Gubong gold-silver deposits if gold-silver-bearing hydrothermal massive quartz veins which were filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits is contained within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Ore minerals are comported mainly of arsenopyrite, pyrite, sphalerite, chalcopyrite, galena with minor amounts of pyrrhotite, marcasite and electrum. The frequency and volume percentages of electrum associated with ore minerals from this deposits are recognized as follows; 44.5% and 54.3% with arsenopyrite, 24.3% and 33.8% with quartz, 12.6% and 0.1% with pyrite, 11.0% and 4.8% with galena, 5.0% and 7.0% with sphalerite and 2.5% and 0.02% with chalcopyrite, respectively. They show irregular (41.6%), subround (34.7%), elongate (17.0%) and granular (6.6%) shapes, respectively. Their grain size ranges from 2 to 150 um, but 90.9 percent of the grains are below 30 um. The chemical composition of electrums ranges from 26.39 to 72.51 Au atomic %. These composition (Au atomic %) on the basis of associated minerals are from 44.97 to 71.75 with arsenopyrite, pyrite, sphalerite and quartz, from 44.37 to 72.51 with quartz, from 35.40 to 41.01 with sphalerite and chalcopyrite, from 26.39 to 54.84 with pyrite, chalcopyrite, quartz and galena, from 28.49 to 53.28 with galena, respectively. We suggest that optimum recovery of gold would be obtained with reference to these results.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.142-142
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• 1999

열역학적 평형하에서 금(Au)은 사파이어(Sapphire: 다결정 Al203)와 반응을 하지 않으므로 접합성이 약하나 사파이어표면을 Ar 이온으로 에칭한후 금박막을 증착하였을 때 후 열처리 없이도 대단히 강한 접합(>70MPa)이 얻어졌다. 접합기구를 규명하기 위해 고 해상도 Auger 전자광분광기로 금/사파이어 쌍의 입계에 Ai-Al-O 화합물이 1-2 원자층 범위내에서 형성되어 있고 7KeV의 Ar 이온에너지로 3분간 조사하을 때 사파이어표면에 환원으로 인한 금속알루미늄이 형성되어 있음이 발견되었다. 이 이온조사로 인한 환원은 선택적 에칭으로 인한 것으로 TRIM 계산결과와도 일치하는 것이다. 따라서 금박막과 이온조사된 사파이어 사이의 강한 접합은 이온조사로 인한 사파이어 표면에 충돌할 때의 운동 에너지가 구동력이 되어 Au-Al-O 화합물의 형성으로 결론될 수 있다.

• The Korean Journal of Zoology
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• v.38 no.1
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• pp.1-9
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• 1995

연두·금파리에서 혈구 세포가 면역반응의 일환으로 일으키는 결절형성(nodule formation) 현상을 형태학적으로 관찰하고자 본 실험이 수행되었다. 연두금파리 종령 유충 체내에 정상 효모, 고정된 대모, 세포액이 제거된 원형질체의 효모를 각각 주입하여 면역반응 과정을 전자현미경으로 관찰하였다 먼저 정상 효모를 주입하였을 경우, 효모와 접촉한 헐구의 과립방출과 곧 이은 혈구의 파괴 그리고 효모 주위에 혈림프와 함께 점액성응혈(clot)의 형성을 관찰 할 수 있었다 점액성 응혈에는 여러 유형의 파괴된 혈구가 포함되어 있었다. 이같은 면역반응에는 체내 혈구 중 과립혈구(granulocyte)가 가장 활발히 반응였고 응혈의 대부분을 형성하였다. 결절의 중심부인 응혈은 대모와 파괴되지 않은 혈구 대 파괴된 혈구 그리고 방출된 과립들로 차 있었고, 효모 주입 3시간 까지는 이같은 응혈은 계속 확대되었다. 그러나 10시간 이후에는 응혈이 관찰되지 않았으며 이때 체강내에서 효모가 관찰되곤 하였다. 고정된 효모를 주입하였을 경우에는 혈구파괴나 과립방출 등이 관찰되지 않았으며, 고정된 효모에 대한 혈구의 식 세포작용만이 관찰되었다. 이 식세포작용은 주입후 10시간 까지 계속되었다. 원형질 체의 효모를 주입하였을 경우에는 혈구에의한 면역반응이 관찰되지 않았다.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.795-801
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• 2012

Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Thiol ligand have been used as stabilizers of metal nanoparticles since Brust et al. They reported the preparation method of ligand capped metal nanoparticles by protecting the nanoparticles with a self-assembled monolayer of dodecanethiolate. In this method, volatile organic compounds (VOCs) were used as sovents. This study was carried out to replace these VOCs with room temperature ionic liquids (RTILs). We used two type of ILs to prepare metal nanoparticles. One is a hydrophobic IL, [BMIM][[$PF_6$] (1-Butyl-3-methylimidazolium hexafluorophosphate) purchased from IL maker, C-Tri from Korea and the other one is a hydrophilic one, [BMIM][Cl] (1-Buthy-3-methylimdazolium chloride) sinthesized by us. In the case of preparing Ag and Au nanoparticles using [BMIM][Cl], we didn't use phase transition reagents and ethanol because it has hydrophilic property and preparing Au, Ag nanoparticles using [BMIM][[$PF_6$] the method is as same as Brust et al.'s except using [BMIM][[$PF_6$] instead of organic solvent because it has hydrophobic property. FT-IR and UV-vis, TEM, TGA analysis have been used in an attempt to determine the particle size and verify functional groups. The particle size obtained from TEM was very similar to those obtained by Brust et al. This is a clear example of ligand capped metal nanoparticles prepared using ionic liquids. And the experimental result demonstrated ionic liquids can act as a highly effective medium for the preparation and stabilization of gold and silver metal nanoparticles.

• Journal of the Mineralogical Society of Korea
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• v.27 no.3
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• pp.115-124
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• 2014

In order to leach Au and Ag from gold-silver bearing sulfide concentrate, the sulfide concentrate was ground in a ball mill for a dry pre-treatment and a wet pre-treatment process. Mineralogical studies and thiourea leaching experiments were carried out with the pre-treated sulfide concentrate. The results of the pre-treatment with the concentrate samples showed the mean particle size and iso-electrical potential was smaller in the dry pre-treatment sample than in the concentrate sample, and the contents was lower in the wet pre-treatment sample than in the dry pre-treatment sample. In XRD analysis, amorphous properties were only shown in the wet pretreatment sample. The results of the concentrate sample leaching experiments showed that the best Au, Ag leaching parameters were when the addition of thiourea was at a 1.0 g concentration, ferric sulfate was 1.0 M, sulfuric acid was 2.0 M and the leaching temperature was at $60^{\circ}C$. The Au, Ag leaching rate was always much greater and faster with the wet pre-treatment samples than with the dry pre-treatment samples. Accordingly, it is expected that more Au, Ag can be leached in an eco-friendly methodology using wet pre-treatment. The pre-treatment could be improved with an optimized grinding additive reagent and through researching grinding time in future non-cyanide processes.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.389-398
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• 1998

The Au-Ag deposit of the Oknam mine occurs as gold-silver-bearing rhodochrosite veins in biotite schist and phyllite of the Precambriam Yulri Group. Five stages of ore deposition are recognized, each showing a definite mineral assemblage. General mineral parageneses in veins (stage III) associated with gold and silver vary inwardly from the vein margin: arsenopyrite + pyrite $\Rightarrow$ sphalerite+chalcopyrite+galena+gold $\Rightarrow$ ga1ena+Ag-bearing minerals. Fluid inclusion data indicate that temperature and salinity of ore fluids overally decreased with time: $345^{\circ}{\sim}240^{\circ}C$ and 3.4~7.8 wt. % NaCl equiv during stage I (quartz vein mineralization), $313^{\circ}{\sim}207^{\circ}C$ and 2.3~8.7 wt.% NaCl equiv during manganese-bearing carbonate stages (II and III), and $328^{\circ}{\sim}213^{\circ}C$ and 3.6-5.4 wt.% NaCl equiv during stage IV (quartz vein mineralization). The ore fluids probably evolved through repeated pulses of boiling and later mixing with cooler and more dilute meteoric waters. Fluid inclusion data and geologic arguments indicate that pressures during the mineralization were in the range of 90 to 340 bars. Gold occurs as silver-rich electrums (21 to 29 atom. % Au) and was deposited at temperatures between $300^{\circ}$ and $240^{\circ}C$. Thermochemical calculations suggest that gold was deposited as a combined result of increase in pH and decreases in temperature, $fs_2$ and $fo_2$.

• Journal of Conservation Science
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• v.26 no.1
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• pp.13-24
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• 2010

This study examined each handiwork method of 4 filigree artifacts from Neungsan-ri temple site in Buyeo, Korea through material characteristic and microstructure analysis. As a result, it was indicated that all of the artifacts have comparatively higher purity than 22.7K and some of filigree artifacts showed that gold is alloyed with silver at a certain ratio. Gold thread that decorates surface showed thickness of 0.2~0.8mm and displayed various forms of section. Gold granule indicated that 2 or 3 granules are adhered together and they are 0.3~0.8mm in diameter. Trace of soldering was observed from gold thread and gold granule joints on surface and it confirmed a possibility of being soldering using gold solder through componential analysis. Also, it reveals a surface decorated with pigments such as cinnabar(HgS) and black.

• Elastomers and Composites
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• v.40 no.4
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• pp.272-276
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• 2005

[ $C_{70}$ ]-gold nanoparticle multilayer films were self-assembled using a 'dirt-ball' method on the reactive surface of glass slides functionalized with 3-aminopropyltrimethoxysilane. The functionalized glass slides were soaked in the solution containing both unmodified $C_{70}$ and ${\omega}$-amino-functionalized gold nanoparticles. Organic reaction (amination) facilitated the assembly of multilayer $C_{70}$-gold nanoparticle films, which have grown up to several layers. Chemical stability of $C_{70}$-gold nanoparticle films was studied by monitoring the changes in absorbance after the immersion of the films in acidic solution. In addition, ultrasonic stability of these nanoparticle films was studied by exposing them to ultrasonic irradiated surrounding, which resulted in partial desorption and a little aggregation of nanoparticles on solid surfaces.

• Journal of Bio-Environment Control
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• v.15 no.3
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• pp.270-276
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• 2006

This experiment was conducted to selecting of oriental melon cultivars suitable for second cropping at summer season. At 20 days after transplanting, 'Supergumssaragi' and 'Gumhwangeunchun' were rapidly growing. Chlorophyll contents of 'Gumgigaeeunchun', 'Gumnodazieunchun', 'Gonggongcheelkkul' and 'Gumboddari' were higher than other cultivars. Days required from transplanting to harvesting of 'Gumboddari', 'Gumdongieunchun', 'Gonggongcheelkkul' and 'Gumgaeeunchun', 'Gumbora' and 'Supergumssaragi', 'Gumssaragieunchun', 'Gumnodazieunchun', 'Gummieunchun' and 'Gumhwangeunchun', 'Diamond' were 51, 52, 53, 55, 56 and 60 days, respectively. The fruit weigh tended to heavy in 'Supergumssaragi' and 'Gumgigaeeunchun'. The flesh thickness was thick a little in 'Gumgigaeeunchun'. The hardness tended to high in 'Gumgigaeeunchun', 'Gumnodazieunchun' and 'Gumgaeeunchun', but it was not difference between treatments. 'L', 'a', 'b' and Y.I. value of the fruit were not difference between the cultivars, but 'a' value was the highest at 'Gumgigaeeunchun', The yield per ha of 'Gumgaeeunchun' and 'Gumgigaeeunchun' increased 8%, 2% than 'Gumssaragieunchun', respectively. From above result, 'Gumgigaeeunchun', 'Gumdongieunchun', 'Gumnodazieunchun' and 'Gumgaeeunchun' cultivars are suitable in summer season.

• Economic and Environmental Geology
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• v.26 no.2
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• pp.117-127
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• 1993

Ag-Au vein ores from the Weolyu mine, Youngdong district, contain significant germanium (up to 145g/t, average 34.9g/t), in the form of argyrodite ($Ag_8GeS_6$). Mineral chemistries of argyrodite and its associated minerals were determined by electron probe microanalysis. Twenty eight elements in thirteen ore samples were analyzed using an ICP mass spectrometer. Argyrodite occurs in the paragenetically later mineral assemblage consisting of carbonates+quartz+native silver+argentite+Ag-sulfosalts, indicating that the germanium mineralization represents the culmination of a complex mineral sequence which includes early gold and late silver deposition. The mean formula of the argyrodite is $Ag_{7.90}\;(Ge_{0.76}Sn_{0.04})S_6$, with minor amounts of Cu, Fe, Sb, As, Sn, and Zn. The Weolyu argyrodite shows systematic substitutions of Ag by Cu, and of Ge by Sb. Chemical analyses of vein ores indicate that metals were precipitated in the order of $Fe{\rightarrow}Pb$, $Zn{\rightarrow}Cu{\rightarrow}Ag$, Sb, As, Ge. Germanium has a strong geochemical affmity with As and Sb, and Cu, Pb, Zn, Mo, and Sr show weak positive correlations with Ge. Germanium deposition at Weolyu was mainly a result of cooling of hydrothermal fluids (down to $175^{\circ}C{\sim}210^{\circ}C$, due to increasing involvement of cooler meteoric waters in the epithermal system.