• Economic and Environmental Geology
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• v.32 no.5
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• pp.445-454
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• 1999

The Sanjeon Au-Ag deposit consists of three subparallel hydrothermal quartz-calcite veins which filled fault-related fractures (generally $N20^{\circ}$ to 35"W-trending and $70^{\circ}$ to $80^{\circ}$ SW-dipping) within quartz porphyry. The vein mineralization shows an apparent variation of mineral assemblages with paragenetic time: (1) early, white quartz + pyrite + arsenopyrite + brown sphalerite, (2) middle, white (vein) to clear quartz (vug) + base-metal sulfides + electrum + argentite, (3) late, calcite + pyrite + native silver. Mineralogic and fluid inclusion data indicate that gold-silver minerals were deposited at temperatures from 2l $0^{\circ}$ to $250^{\circ}$ with salinities of 4 to 5 wt. % equiv. NaCl and log fS2 values from -14.0 to -12.2 atm. The linear relationship between homogenization temperature and salinity data indicates that gold-silver deposition was a result of meteoric water mixing. Ore mineralization occurred at pressure conditions of about 70 bars, which corresponds to the mineralization depths of about 260 m to 700 m. There is a remarkable decrease of the calculated 1)180 values of water from 1.3 to -9.7%0 in hydrothermal fluid with increasing paragenetic time. This indicates a progressive increase of meteoric water influx in the hydrothermal system at the Sanjeon deposit. Oxygen-hydrogen, sulfur, and carbon isotope values of hydrothermal fluids indicate that the ore mineralization was formed largely from meteoric waters with the contribution of sulfur and carbon from a deep igneous source.

• Economic and Environmental Geology
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• v.25 no.2
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• pp.115-131
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• 1992

Late Cretaceous (90.5 Ma), epithermal gold-silver vein mineralization of the Weolseong and Samchang mines in the Sulcheon area, 60 km southeast of Taejeon, can be separated into two distinct stages (I and II) during which fault-related fissures in Precambrian gneiss and Cretaceous (102 Ma) porphyritic granite were filled. Fluid inclusion and mineralogical data suggest that quartz-sulfide-electrum-argentite-forming stage I evolved from initial high temperatures $({\approx}340^{\circ}C})$ to later lower temperatures $({\approx}140^{\circ}C})$ at shallow depths of about 400 to 700 m. Ore fluid salinities were in the range between 0.2 and 6.6 wt. % eq. NaCl. A simple statistic model for fluid-fluid mixing indicates that the mixing ratio (the volumetric ratio between deep hydrothermal fluids and meteoric water) systematically decreased with time. Gold-silver deposition occurred at temperatures of $230{\pm}40^{\circ}C$ mainly as a result of progressive cooling of ore-forming fluids through mixing with less-evolved meteoric waters. Measured and calculated hydrogen and oxygen isotope values of hydrothermal fluids indicate meteoric water dominance, approaching unexchanged meteoric water values. The geologic, mineralogic, and geochemical data from the Weolseong and Samchang mines are similar to those from other Korean epithermal gold-silver vein deposits.

• Elastomers and Composites
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• v.50 no.3
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• pp.223-230
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• 2015

Bacterial infection is one of the most common and universal cause of disease spreading associated with medical and surgical environment. Antimicrobial function of plasticized polyvinyl chloride (PVC) will be useful for making hygienic environments. Here, we synthesized the PVC composite by the addition of inorganic bacteriocide containing silver, zinc and zeolite. And we investigated the growth inhibition rate for Staphylococcus aureus and Klebsiella pneumoniae which were analyzed in the presence of PVC composite with different doses of inorganic bacteriocide (1~15 wt%). Bacterial proliferation was significantly inhibited by 3 wt% of inorganic bacteriocide containing PVC composite. And we found the inhibition of bacterial biofilm formation by 5 wt% of inorganic bacteriocide containing PVC composite by the observation of scanning electron microscopy (SEM). Our data suggested that the antimicrobial effect of inorganic bacteriocide was caused by disturbing the bacterial biofilm formation.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.119-127
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• 1996

Electrum-sulfide minerals of the Namsan Au-Ag mine were deposited in two stages of quartz and calcite veins that fill fault planes in Mesozoic granitic rocks (230~155 Ma). The K/Ar radiometric dating of hydrothermal sericite indicates that mineralization is early Cretaceous age ($127{\pm}3.0Ma$). Mineralogic, fluid inclusion and sulfur isotopic data show that ore minerals were deposited at temperatures between $340^{\circ}C$ and $200^{\circ}C$ from fluid with salinities of 3 to 6 equiv. wt % NaCl. Evidence of fluid boiling (and $CO_2$ effervescence) indicates a maximum pressures of 100 bars. The formation temperature and $fs_2$, of Au-mineralization from the Namsan mines are mainly $280{\sim}230^{\circ}C$ and $10^{-11}{\sim}10^{-13}$ atm, respectively. Au deposition was likely a result of boiling caused to chemical change (pH, $f_{O2}$, ${\Sigma}_{H_2S{\cdot}{\cdot}}$) of ore-fluids. Sulfur isotope composition of sulfide minerals (${\delta}^{34}S=5.1$ to 8.2‰) are consistent with ${\delta}^{34}S_{{\Sigma}{H2S}}$ value of +6 to +7‰, suggesting an igneous source of sulfur partially mixed with wall-rock sulfur.

• Current Photovoltaic Research
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• v.4 no.2
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• pp.54-58
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• 2016

Laser-doped selective emitter process requires dopant source deposition, spin-on-glass, and is able to form selective emitter through SiNx layer by laser irradiation on desired locations. However, after laser doping process, the remaining dopant layer needs to be washed out. Laser-induced melting of pre-deposited impurity doping is a precise selective doping method minimizing addition of process steps. In this study, we introduce a novel scheme for fabricating highly efficient selective emitter solar cell by laser doping. During this process, laser induced damage induces front contact destabilization due to the hindrance of silver nucleation even though laser doping has a potential of commercialization with simple process concept. When the laser induced damage is effectively removed using solution etch back process, the disadvantage of laser doping was effectively removed. The devices fabricated using laser doping scheme power conversion efficiency was significantly improved about 1% abs. after removal the laser damages.

• Journal of the Korean Chemical Society
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• v.40 no.7
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• pp.474-482
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• 1996

Two crystal structures of the vacuum dehydrated $Ag^+$-exchanged zeolite X have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1)$^{\circ}C$ (a=24.922(1)${\AA}$ and a=24.901(1)${\AA}$, respectively). Each crystal was ion exchanged in flowing streams of aqueous $AgNO_3$ for three days. The first crystal was dehydrated at 300$^{\circ}C$ and $2{\times}10^{-6$torr for two days. The second crystal was similarly dehydrated at 350$^{\circ}C$. Their structures were refined to the final error indices, $R_1=0.095\;and\;R_2=0.092$ with 227 reflections, and $R_1=0.096\;and\;R_2=0.087$ with 334 reflections, respectively, for which I > 3${\sigma}$(I). In the first crystal, Ag species are found at five different crystallographic sites: sixteen $Ag^+$ ions fill the site I, the center of the double 6-ring, thirty-two Ag0 atoms fill the I' site in the sodalite cavities opposite double six-rings, seventeen $Ag^+$ ions lie at the 32-fold site II' inside the sodalite cavity at the single six-oxygen ring in the supercage, fifteen Ag+ ions lie at the 32-fold site II, in the supercage, and the remaining twelve $Ag^+$ ions lie at site III' in the supercage at a little off two-fold axes. In the second crystal, all Ag species are located similarly as crystal 1; 16 at site I, 28 at site I', 16 at site II, 16 at site II', 6 at site III and 6 at site III'. Total 88 silver species were found per unit cell. The remaining four Ag atoms were migrated out of the zeolite framework to form small silver crystallites on the surface of the zeolite single crystal. In the first structure, the numbers of Ag atoms per unit cell are approximately 32.0 and these may form tetrahedral $Ag_4$ clusters at the centers of the sodalite cavities. The probable four-atom cluster is stabilized by coordination to two $Ag^+$ ions. The Ag-Ag distance in the cluster, ca. 3.05 ${\AA}$, is a little longer than 2.89 ${\AA}$, Ag-Ag distance in silver metal. At least two six-ring $Ag^+$ ions on sodalite cavity (site II') must necessarily approach this cluster and this cluster may be viewed as a distorted octahedral silver cluster, (Ag6)2+.

• Economic and Environmental Geology
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• v.26 no.4
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• pp.433-444
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• 1993

Electrum (32~73 atom. % Ag)-sulfide mineralization of the Bodeok mine in the Boseong area was deposited in two stages of mineralogically simple, massive quartz veins that fill the fractures along fault shear zones in Precambrian gneiss. Radiometric dating indicates that mineralization is Late Jurassic age ($155.9{\pm}2.3$ Ma). Fluid inclusion data show that ore mineralization was formed from $H_2O-CO_2$ fluids with variable $CO_2$ contents ($X_{CO_2}=0.0$ to 0.7) and low salinities (0.0 to 7.4 wt. % eq. NaCl) at temperatures between $200^{\circ}$ and $370^{\circ}C$. Evidence of fluid unmixing ($CO_2$ effervescence) indicates pressures up to 1 kbar. Gold-silver deposition occurred later than base-metal sulfide deposition, at temperatures near $250^{\circ}C$ and was probably a result of cooling and decreasing sulfur activity caused by sulfide precipitation and/or $H_2S$ loss (through fluid unmixing). Calculated sulfur isotope compositions of ore fluids (${\delta}^{34}S_{{\Sigma}S}=1.7$ to 3.3‰) indicate an igneous source of sulfur in hydrothermal fluids. Measured and calculated O and H isotope compositions of ore fluids (${\delta}^{18}O_{water}=4.8$ to 7.2‰, ${\delta}D_{water}=-73$ to -76‰) indicate that mesothermal auriferous fluids at Bodeok were likely mixtures of $H_2O-rich$, isotopically evolved meteoric waters and magmatic $H_2O-CO_2$ fluids.

• Applied Microscopy
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• v.36 no.4
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• pp.271-277
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• 2006

Mast cells (MCs) are granulated cells that play a pivotal role in allergic reaction and inflammation. The granules of mast cells are known to be rich in zinc (Zn). Male Sprague-Dawley rats were used. We injected $200{\mu}L$ of complete Freund's adjuvant (CFA) subcutaneously in the dorsal aspect of one hindpaw Finally, zinc selenium autometallography(AMG) was done by Danscher's method. The present study showed the ultrastructures of zinc-containing mast cells found in inflammatory area following an complete freund's adjuvant (CFA) inoculation into the rat hindpaw. At light microscopic level, mast cells were round or oval, at average $12{\mu}m$ in diameter, with many filopodia extending from the cell surface. Because the rather small and spherical nucleus was centrally placed; it was frequently obscured by the cytoplasmic granules, it sometimes could not be seen. Mast cells were distributed chiefly in the vicinity of small blood vessels. In most preparation many mast cells were ruptured and their granules escaped into the surrounding tissue. In electron micrographs, The secretory granules were at average $0.5{\mu}m$ in diameter and were limited by a membrane. The cell surface contained numerous microvilli and folds. Their interior was heterogenous in appearance. The nucleus was surrounded by large numbers of prominent vesicels and a well developed Golgi apparatus, but scant endoplasmic reticulum.