• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.33-51
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• 2013

Spatial and temporal characteristics of nitrate contamination and hydrogeochemical parameters were investigated for springs and surficial and bedrock groundwaters in northeastern part of Hongseong. Two field investigations were conducted at dry and wet seasons in 2011 for 120 sites including measurement of field parameters with chemical analyses of major dissolved constituents. Nitrate concentrations were at background levels in springs while 45% of bedrock groundwater and 49% of surficial groundwater exceeded the drinking water standard of nitrate (10 mg/L as $NO_3$-N). The difference in nitrate concentrations between surficial and bedrock groundwater was statistically insignificant. Cumulative frequency distribution of nitrate concentrations revealed two inflection points of 2 and 16 mg/L as $NO_3$-N. Correlation analysis of hydrogeochemical parameters showed that nitrate had higher correlations with Sr, Mg, Cl, Na, and Ca, in surficial groundwater in both dry and wet season. In contrast, nitrate had much weaker correlations with other hydrogeochemical parameters in bedrock groundwater compared to surficial groundwater and had significant correlations only in wet season. Temporally, nitrate and chloride concentrations decreased and dissolved oxygen (DO) increased from dry season to wet season, which indicates that increased recharge during the wet season affected groundwater quality. Aerobic conditions were predominant for both surficial and bedrock groundwater indicating low natural attenuation potential of nitrate in the aquifers of the study area.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.599_600
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• 2009

In superconducting magnetic energy storage (SMES) systems, the current leads are usually divided into two parts. Normal metals like brass or copper are often used in the first part from the room temperature to the 1st stage of the cryocooler. Their dimensions were decided to minimize the conduction heat penetration and Ohm's heat generation. The second part down to the cryogenic coil is made of high temperature superconductor (HTS). HTS current leads can reduce the conductive heat penetration because they have poor thermal conductivity and generate no Ohm's heat generation. The brass current lead and the HTS current lead were designed and fabricated for application to the 10kJ class SMES system. The HTS current lead is 300A class. The HTS current lead was stacked with 2 HTS layers using the $Bi_2Sr_2Ca_2Cu_3O_x$ (BSCCO)/Ag. In this paper, we introduce the design procedure of the current leads and discuss the test results of the current leads.

• Economic and Environmental Geology
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• v.28 no.2
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• pp.123-137
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• 1995

The Mesozoic Geumsan granitic rocks of various composition are distributed in the Geumsan district, the central part of the Ogcheon Fold Belt. About 40 ore deposits of $CaF_2{\pm}Au{\pm}Ag{\pm}Cu{\pm}Pb{\pm}Zn$ are widely distributed in this district and are believed to be genetically related to the granitic rocks. Based on their petrography and geochemistry, the granitic rocks in this district can be classified into two groups ; the Group I( equigranular leucocratic granite, porphyritic biotite granite, porphyritic pink-feldspar granite, seriate leucocratic granite) and the Group II(seriate pinkfeldspar granite, equigranular alkali-feldspar granite, equigranular pink-feldspar granite, miarolitic pink-feldspar granite, equigranular biotite granite). Interpreted from their isotopic dating data and geochemical characteristics, the Group I and the Group II are inferred to be emplaced during the Jurassic(~184Ma), and the Cretaceous to the early Tertiary period(~59Ma), respectively. Both Group I and Group II generally belong to magnetite-series granitoids. The Cretaceous granitic rocks of Group II are more highly evolved than those of the Jurassic Group I. The Rb-Sr variation diagram suggests that the granitic rocks of the Jurassic Group I and of the Cretaceous Group II be evolved mainly during the processes of fractional crystallization and partial melting, respectively.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.166-172
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• 1997

Aspergillus niger was selected as a strain producing the potent raw starch hydorlyzing enzyme. These experiments were conducted to investigate the conditions of the glucoa- mylase production, the purification of the enzyme, some characteristics of the purified enzyme and hydrolysis rate on various raw starches such as com, rice, potato, glutinous rice, sweet potato, wheat and barley. The optimum cultural temperature and time for the enzyme production on wheat bran medium were $30^{\circ}C$ and 96hrs, respectively. The respective addition of yeast extract and nutrient broth on wheat bran medium increased slightly the enzyme production. The enzyme was purified by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The specific activity of the purified enzyme was 30.7u/mg-protein and the yield of enzyme activity was 25.8%. The purified enzyme showed a single band on polyacrylamide disc gel electrophoresis and its molecular weight was estimated to be 56,000 by SDS-polyacrylamide disc gel electrophoresis. The isoelectric point for the purified enzyme was pH3.7. The optimum temperature and pH were $65^{\circ}C$ and pH 4.0, respectively. The purified enzyme was stable in the pH range of pH 3.0-9.5 and below $45^{\circ}C$, and its thermal stability was slightly increased by the addition of $Ca^{2+}$. The purified enzyme was activated by $Co^{2+},\;Sr^{2+},\;Mn^{2+},\;Fe^{2+},\;Cu^{2+}$. Raw rice starch, raw corn starch, raw glutinous rice starch, raw sweet potato starch, raw wheat starch and raw barley starch showed more than 90% hydrolysis rate in 48hrs incubation. Even raw potato starch, most difficult to be hydrolyzed, showed 80% hydrolysis rate. The purified enzyme was identified as glucoamylase.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.81-89
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• 2009

In this study, we conducted heat-treatment on freshwater cultured pearls at various conditions in other to improve their color. Also, after heat treatment, we used the UV-Vis, ED-XRF and SEM to investigate changes freshwater cultured pearls' color, composition and internal structure. UV-Vis analysis showed the reflectivity of samples increased at most heat-treatment conditions although the reflectivity decreased at a certain temperature and duration. At $100^{\circ}c$/8 h, $120^{\circ}c$/6 h and $140^{\circ}c$/4 h, the reflectivity increased highest. In proportion to reflectivity increase, freshwater cultured pearls' color was improved. Ca, Mn, Sr and other micro elements were found from ED-XRF analysis. However, changes in composition of elements were not detected. It was found that the content of Mn in freshwater cultured pearl is higher than other micro elements. From SEM analysis, aragonite's shape was shown in narce and some of the narce were condensed after heat treatment.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.865-875
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• 2016

In this study, mass concentrations and chemical compositions of $PM_{2.5}$, including water-soluble ions and elements were determined at the 1,100 m-highland of Mt. Hallasan in Jeju Island across four seasons from August 2013 to August 2014. The average mass concentration of $PM_{2.5}$ was $12.5{\pm}8.41{\mu}g/m^3$ with 45.8% of the contribution from eight water-soluble ionic species. Three ionic species ($SO{_4}^{2-}$, $NH{_4}^+$, and $NO{_3}^-$) comprised 96.2% of the total concentration of ions contained in $PM_{2.5}$ and were the dominant ions, accounting for 43.5% of the $PM_{2.5}$ mass at Mt. Hallasan. On the basis of the mass concentration level, seasonal variation, enrichment factor, and relationship among elements, we can presume that Mg, K, Ca, Mn, Fe, Co, Sr, Ba, Nd, and Dy originated mainly from crust or soil and that V, Cr, Ni, Cu, Zn, As, Cd, and Pb were significantly enriched in $PM_{2.5}$ owing to the effects of the anthropogenic emissions. These results and the local distribution of emission sources and topographic characteristics near this sampling site suggest that the compositions of $PM_{2.5}$ collected at the 1100 m-highland of Mt. Hallasan were largely influenced by inflow from outside of Jeju Island.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.338-341
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• 2004

This study was carried out to understand the geochemistry of saline water circulating in an ash disposal pond of Seocheon power plant, Korea. For this study, ash pond waters, slurry water and seawater samples were collected and analyzed for major ions and trace elements. Results show that ash pond waters and slurry water are alkaline in nature due to high calcium content, and have high concentration of Ca, B, Li, As, Ba, Al, Si and Mn over seawater, suggest that these elements leached from fly ash even at high alkaline condition and ionic strength. Slurry water has high concentration of B, Ba, Li, Mn, Si and Sr compare to ash pond waters, expresses that these elements seem to be easily reached at initial stage fly ash-water interaction, and also might be associated with the surface of the fly ash particles. Additionally, PHREEQC program predicted several secondary solid phases, which are also influenced in the leaching of elements in to the saline water.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.3
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• pp.143-153
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• 1989

In conclusion, a high-Tc superconducting YBa sub(2) Cu sub(3) O sub(y) phase with zero resistance at about 90K was successfully prepared by nitrate solution method with densed micro structure. The result of the EDAX analysis on the isolated particles using the microscopic meissner effect showed that the particles were isolated at higher temperature due to the differences in O vacances rather than the differences in chemical compositions. The composition of the isolated particles were almost identical to the starting compositions on the samples prepared by the solid reaction and nitrate solution method but the Ba-rich composition were seen in the coprecipitated sample. The isolation process on Bi system was not successful due to the weak dimagnetism even though its high Tc above the liquid nitrogen temperature.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.147-163
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• 2000

The mineralogy and chemical composition of reddish to brownish yellow residual soils, so called "Hwangto" have been examined according to representative host rocks. The result of the study indicates that Hwangto consists of 40-80% clay minerals and various minerals such as quartz, feldspar, hornblende, goethite, and gibbsite. Clay minerals include kaolinite, halloysite, illite, hydroxy interlayered vermiculite (HIV), mica/vermiculite interstratifield mineral and chlorite. The mineralogical constituents and contents of Hwangto were different depending on the types of host rocks. Moreover, the Jurassic granitic rocks contain relatively more kaolin minerals, whereas the Cretaceous granitic rocks contain more HIV and illite. In addition, reddish Hwangto contains relatively more kaolinite and HIV, and yellowish Hwangto contains more illite and halloysite. It is suggested that feldspars and micas of host rocks were chemically weathered into illite, halloysite, illite/vermiculite interstratified minerals, and HIV, and finally into kaolinite. Compared with their host rocks, the major chemical compositions of Hwangto tend to contain more $Al_2O_3,\;Fe_2O_3,\;H_2O$ in amount and less Ca, Mg, and Na. Hwangto contains relatively high amount of trace elements, P, S, Zr, Sr, Ba, Rb, and Ce including considerable amount of Li, V, Cr, Zn, Co, Ni, Cu, Y, Nb, La, Nd, Pb, Th in excess of 10 ppm. Relatively high amount of most trace elements were detected in the Hwangto. The major and minor chemical compositions of the Hwangto were different depending on the types of host rocks. However, their difference was in the similar range compared with the compositions of host rocks.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.885-890
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• 2004

A survey for vesicular-arbuscular mycorrhizae (VAM) occurrence was undertaken in three endangered vegetation sites in the area of Kudankulam atomic power station. Fifteen VAM fungal species were isolated from the root-zone soils of fourteen different plant species. There was a significant correlation observed between the number of spores and of percentage root colonization as exemplified by Phyllanthus niruri and Paspalum vaginatum (450, 95%; 60, 25%). Although VAM species are not known to be strictly site specific, the fact that Acaulospora elegans was observed only in site 1, Glomus pulvinatum in site 2 only, and Gl. intraradices in site 3 only, showed site-specificity in this study. To confirm the infection efficiency, two host plant species in the sites, P. niruri and Eclipta alba, were selected and inoculated in field with three selected VAM fungal spores. Gl. fasciculatum was found to be the most efficient VAM species in percentage root colonization, number of VAM spores, and dry matter content. When the nutrients in roots of P. niruri and E. alba were analyzed, there was higher uptake of K (4.2 and 3.4 times, respectively) and Ca (5.3 and 4.9 times, respectively), the analogues for $^{137}Cs$ and $^{90}Sr$, respectively. From the results, it might be concluded that VAM association helps the plants survive in a disturbed ecosystem and enhances uptake and cycling of radionuclides from the ecosystem.