• Economic and Environmental Geology
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• v.34 no.5
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• pp.423-435
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• 2001

The gold-silver vein deposits in the Mugeug mineralized area are emplaced in late Cretaceous biotite granite associated with the pull-apart type Cretaceous Eumseong basin. Mugeug mine in northern part is composed of multiple veins showing relatively high gold fineness and is characterized by sericitization, chloritization and epidotization. The ore-forming fluids were evolved by dilution and cooling mechanisms at relatively high temperature and salinity (=30$0^{\circ}C$,1~9 equiv. wt. % NaCl) and highly-evolved meteoric water ($\delta$$^{18}$ O;-1.2~3.7$\textperthousand$) and gold mineralization associated with sulfides tormed at temperatures between 260 and 22$0^{\circ}C$ and within sulfur fugacity range of 10$^{-11.5}$ ~ 10$^{-13.5}$ atm. In contrast, Geumwang, Geumbong and Taegueg mines show the low fineness values, in southern part are characterized by increasing tendency of simple and/or stockwork veins and by kaolinitization, silicificatitan, carbonatization and smectitization. These droposits formed at relatively low temperature and salinity (<23$0^{\circ}C$, <3 equiv. wt. % NaCl) from ore-forming fluids containing greater amounts of less-evolved meteoric waters ($\delta$$^{18}$ O;-5.5~4.0$\textperthousand$), and silver mineralization representing various gold-and/or silver-bearing minerals formed at temperatures between 200 and 15$0^{\circ}C$ and from sulfur fugacity range of 10$^{-15}$ ~10$^{-18}$ atm These results imply that mineralization in the Mugueg area formed at shallow-crustal level and categorize these deposits as low-sulfidation epithermal type. The genetic differences between the northern and southern parts reflect the evolution of the hydrothermal system due to a different physicochemical environment from heat source area (Mugeug mine) to marginal area (Taegeum mine) in a geothermal field.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.273-280
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• 2003

Saline conditions invoke oxidative stress attributed to the overproduction of reactive oxygen species (ROS). Changes in quantum efficiency and antioxidative enzyme activity upon salt treatment were examined in a salt-tolerant plant, Atriplex gmelini, to test the hypothesis that salt tolerance of A. gmelini is due to the increased activity of antioxidative enzymes. A. gmelini showed optimum growth at 100 mM NaCl producing 116% of the shoot dry weight over control plants in 0 mM NaCl treatment. Healthy growth persisted up to 300 mM NaCl treatment maintaining normal internal water content and dry weight. No photochemical stress or damages on antioxidative defense system was obvious in plants of 2 and 4 day salt treatment which was indicated by increased quantum efficiency (Fv/Fm value), decreased stress index (Fo/Fm value), and increased activity of antioxidative enzymes such as SOD, APX, GR. However, the plants treated with 400 mM NaCl showed decrease in growth and in antioxidative enzyme activity although the enzyme activity was still higher than that of the 0 mM NaCl treated plants (l31%, 114%, and 134% of the SOD, APX, and GR activity, respectively). Interestingly, another important antioridative enzyme that scavenges H₂O₂ in plant cells, CAT, showed rapid decrease in its activity as salt concentration increased; 38%, 22%, 15% of the 0 mM NaCl treated plants at 200, 300, 400 mM NaCl treatments, respectively. It appears that the enzymes in ascorbate-glutathione cycle such as APX and GR play the major roles in scavenging ROS produced by salt stress in A. gmelini. After 6 days of salt treatment, the damage in photochemical and antioxidative defense system was indicated by decreased Fv/Fm value and increased Fo/Fm value. A. gmelini appears to cope with short term salt treatment by enhanced activity of the antioxidative defense system, whereas long term stress invoke oxidative stress by increased ROS due to the damages in photochemical and antioxidative system.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.117-123
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• 2018

In this study, the efficiency of photosynthetic electron transfer according to LED color temperature was verified in order to find a way to efficiently grow trees under night illumination. The experiment was carried out with White treatment, Warmwhite treatment, and non-treatment with donarium cherry. The study uses to a method for analyzing and evaluating the color temperature of an LED light source by photochemical analysis. We found that all treatments 115 DAT of maximum fluorescence amount(P) had the lowest. In the treatment using white light and the Warm-white light, the T amount of florescence of the late stage during the transition of the J-I level was increased, and the photosystem I electron transfer efficiency was decreased. Therefore, the electron transport efficiency of $RE1_O/CS$ and RE1o/RC were reduced. Especially, compared to Warmwhite, the light intensity increased greatly in the white-light treatment, The $PI_{TOTALABS}$ of 7 DAT was the highest value, but it was decreased to the lowest value on 115 DAT. This study has shown that the white treatment was low in electron transfer efficiency and soundness. Warmwhite-light treatments showed lower stress.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.301-306
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• 2010

The present work is performed to photocatalytically reduce Cr(VI) by means of metal deposited anodized $TiO_2$ tubes, which are prepared by anodization of Ti foil followed by metal deposition. Stably immobilized photo-reactive materials are favored in the field of detoxification in a conventional aqueous medium, preventing gradual loss of efficiency and process malfunction due to detachment of the materials. The prepared samples are characterized by SEM, TEM, EDAX, and photocurrent. The metal deposited-$TiO_2$ electrode shows higher efficiency for Cr(VI) reduction (ca. 20%) and higher ability for adsorption (4~5 times) than pure one.

• Clean Technology
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• v.4 no.1
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• pp.35-44
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• 1998

Photodecomposition behaviors of volatile organic compounds (VOCs ; benzene, toluene, ethylbenzene and xylenes) over UV irradiation and UV irradiation with $TiO_2$ powder catalyst were studied and the extent of degradation were also investigated under various reaction conditions. The reactions were conducted in a quartz annular reactor equipped with a medium pressure mercury lamp. As a result, the extents of degradation were 92% for toluene and ethylbenzene, 83% for benzene, and 82% for xylenes under UV irradiation. And they were 92% for toluene, 82% for xylene and ethylbenzene, and 53% for benzene under UV irradiation with $TiO_2$ powder. Analyses of reacted samples by FID-gas chromatograph with Purge & Trap concentrator and GC-MS indicated that the aromatics formed many intermediates.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.2
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• pp.77-127
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• 1999

활성 산소종은 노화, 특히 피부노화의 원인 물질로 작용하고 있다. 피부는 자외선에 노출되어 있어 활성 산소종을 만드는 광화학적 반응들이 계속해서 일어나고 있다. 이들 활성 산소종들은 피부 세포 및 조직 손상을 주도한다. 이들은 항산화 효소와 비효소적 항산화제들로 구성된 항산화 방어망을 파괴함으로써 산화제/항산화제 균형을 산화 상태 쪽으로 기울게 한다. 결과적으로 계속된 산화적 스트레스는 지질 과산화, 단백질 산화, 간질 성분을 파괴시키는 단백질분해효소의 활성화, 탄력 섬유인 콜라겐과 엘라스틴의 사슬절단 및 비정상적인 교차결합, 히아루론산 사슬의 절단, 멜라닌 생성반웅 촉진, DNA 산화와 같은 생체 구성 성분들의 손상을 야기시킨다. 결국에는 탄력감수 주름살 및 기미.주근깨 둥으로 특징 지워지는 피부노화가 가속화된다. 따라서 피부노화 방지를 위해서는, 과잉의 활성 산소종 생성을 억제하고 또한 생성된 활성산소를 효율적으로 제거할 수 있는 시스템이 화장품의 처방에 반드시 포함될 필요가 있다. 즉, 산화제/항산화제 밸런스가 유지되는 피부의 항산화 방어 시스템 구축이 필요하다. 피부노화 방지에 있어서 천연물의 역할로 (1) 자외선 흡수제로서의 역할, (2) 항산화제로서의 역할, (3) 주름 개선제로서의 역할, (4) 미백제로서의 역할, (5) 항균\ulcorner항염작용 및면역 조절제로서의 역할에 대하여 살펴 보았다. 21세기는 본격적으로 기능성 화장품 시대가 개막될 것으로 예측하고 있다. 이에 맞춰 천연물들은 피부노화를 방지하는데 주도적인 역할을 할 것으로 기대된다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.2
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• pp.156-163
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• 2005

This study was conducted to compare the physiological and biochemical responses of P. orientalis and L. tulipifera in response to ozone. One-year-old seedlings of P. orientalis and L. tulipifera were exposed to 100 ppb ozone concentration for 2, 4, or 8 hr/day for 1 week. Photosynthesis, stomatal conductance and ozone uptake rate were measured daily, and chlorophyll fluorescence, carboxylation efficiency, chlorophyll content, and SOD activity were measured after 1 week. In P. orientalis, photosynthesis and stomatal conductance were not decreased in the 2h/day ozone treatment, but the L. tulipifera response was more sensitive even in the 2h/day ozone treatment. Increased treatment time decreased photosynthesis and stomatal conductance. Chlorophyll fluorescence was not significantly different among treatment times. However, carboxylation efficiency decreased with increased treatment time, and L. tulipifera was more sensitive than P. orientalis. Chlorophyll content did not differ with species or treatment time. SOD activity response was greater in L. tulipifera than in P. orientalis, increasing to $131\%$ of pretreatment observations. Therefore it was concluded that L. tulipifera was more responsive and had lower ozone tolerance than P. orientalis.

• Geophysics and Geophysical Exploration
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• v.23 no.3
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• pp.149-156
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• 2020

The genesis of ore bodies is a very diverse and complex process, and the target depth of mineral exploration increases. These create a need for predictive mineral exploration, which may be facilitated by the advancement of machine learning and geological database. In this study, we confirm that the faults and igneous rocks distributions and magnetic data can be used as input data for potential mapping using deep neural networks. When the input data are constructed with faults, igneous rocks, and magnetic data, we can build a potential mapping model of the metal deposit that has a predictive accuracy greater than 0.9. If detailed geological and geophysical data are obtained, this approach can be applied to the potential mapping on a mine scale. In addition, we confirm that the magnetic data, which provide the distribution of the underground igneous rock, can supplement the limited information from the surface igneous rock distribution. Therefore, rather than simply integrating various data sets, it will be more important to integrate information considering the geological correlation to genesis of minerals.

• Economic and Environmental Geology
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• v.30 no.1
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• pp.61-65
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• 1997

Cadmium occurs as a minor element in sphalerite ((Zn, Fe)S) from the Boseong-Jangheung gold-silver mine district. We analyzed the abundance of cadmium in sphalerite using an electron probe micro analyzer (EPMA) and discussed the natural sources of cadmium in terms of bedrock geochemistry, in order to preliminarily reconnoiter the potential cadmium contamination in mine districts. Cadmium contents of sphalerites from the Au-Ag mines (Bodeok, Mundeok, Jeonbo, Boknae, Keumsan) in the Boseong-Jangheung district are considerably high, compared with cadmium contents of sphalerites (average = 0.5 wt.% Cd, maximum = 4.4 wt.% Cd) in the world. Sphalerites from the Keumsan mine (average = 9.49 wt.% Cd, maximum=11.22 wt. Cd) are highly enriched in cadmium. Our data suggest that the Boseong-Jangheung area is an important potential site of cadmium contamination in Korea. Based on bedrock geochemistry, natural causes of cadmium enrichment in sphalerite from the mine district are thought to be the mixing of cadmium leached from organic-rich, metasedimentary rocks (including coal) and/or black shales. From this study, we propose that the pinpointing of potential sites of pollution by toxic heavy metals can be done effectively through detailed reconnaisance study on mineralogical compositions of ore minerals such as sphalerite from the mine area.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.479-487
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• 2018

The purpose of this study is to analyze photochemical activity of nursery seedlings under drought stress, using chlorophyll fluorescence reaction analysis. Young nursery seedlings of tomato (Lycopersicon esculentum Mill.) and cucumber (Cucumis sativa L.), were grown under drought stress for 8 days. Analysis of chlorophyll fluorescence reaction (OJIP) and parameters, were performed to evaluate photochemical fluctuation in nursery seedlings under drought stress. Chlorophyll fluorescence reaction analysis showed maximal recorded fluorescence (P) decreased from the 5 day after treatment in tomato seedlings, while an amount of chlorophyll fluorescence increased at the J-I step. Thus, physiological activity was reduced. In cucumber seedlings, maximal recorded fluorescence (P) and maximal variable fluorescence ($F_V$) lowered from the 4 day after treatment, and chlorophyll fluorescence intensity of J-I step increased. Chlorophyll fluorescence parameter analysis showed electron transfer efficiency of PSII and PSI were significantly inhibited with decreasing $ET2_O/RC$ and $RE1_O/RC$ from the 5 day after treatment, in tomato seedlings and from the 4 day after treatment, in cucumber seedlings. $ET2_O/RC$ and $PI_{ABS}$ significantly changed. In conclusion, 6 indices such as $F_V/F_M$, $DI_O/RC$, $ET2_O/RC$, $RE1_O/RC$, $PI_{ABS}$ and $PI_{TOTAL}ABS$ were selected for determining drought stress in nursery seedlings. Drought stress factor index (DFI) was used to evaluate whether the crop was healthy or not, under drought stress. Cucumber seedlings were less resistant to drought stress than tomato seedlings, in the process of drought stress.