• Economic and Environmental Geology
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• v.34 no.1
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• pp.105-117
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• 2001

The characteristics of hydrogeochemistry and fluorine distribution in drinking groundwater from limestone and granite were studied in the Keumsan-Wanju area, where major important fluorite-deposits are distributed. The hydrochemical properties of groundwater from studied area arc commonly characterized as $Ca-HC0_3$ water type. However, some of the groundwater samples collected from Jurassic and Cretaceuus granites belong to $Ca-Na-HC0_3 and Na-HC0_3$ type, respectively. The contamination of drinking groundwater by minewater from the nearby fluorite deposits is not found yet. However, groundwater having high F contents up to 1].4 mgll, which is higher than the drinking water limit, is found from the wells located in Cretaceous granite. The tluorine contents in groundwater generally increase with increasing well depth. The concentrations of F in the groundwater show a positive relationship with the values of Na, $HC0_3, Cl. Si0_2$, pH, whereas a negative relationship with Ca. The positive correlation of F-concentrations to major elements ($Si0_2$, Na, CI) and trace elements (Li, B, Rb) may suggest that the groundwater come from the decomposition of tluoride-bearing silicate minerals within highly differentiated granitic rocks, Therefore, wells for drinking water should not be developed or should be drilled within shallow level in the Cretaceous granite region to reduce the F contents in the groundwater.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.350-357
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• 2000

This paper evaluated the influence of point source and flow events on inorganic nitrogen fractions at 17 sites of Taechung Reservoir during 1993${\sim}$1994. Total nitrogen (TN) averaged 1.53 mg/L during the study and ranged between 0.70 and 2.56 mg/L. Dissolved inorganic nitrogen(DIN) accounted for >90% of TN regardless of season and location, indicating a nitrogen-rich system showing eutrophic${\sim}$hypereutrophic conditions. Some 67${\sim}$94% of DIN was NO$_{3}$-N, whereas mean level of NH$_{4}$-N was less than 5% of DIN. During monsoon 1993, dilution of NO$_{3}$-N was evident in the headwaters as a result of mixing of lake water with rain water, while NH$_{4}$-N increased>100% compared to the premonsoon. Values of NH$_{4}$-N had a positive correlation with rainfall (r=0.85; p<0.001) and negative correlations with theoretical water residence time(r=-0.90; p<0.001) and conductivity(r=-0.78, p<0.001), respectively. These outcomes suggest that NH$_{4}$-N came from external input from the watershed during the monsoon. In both years, mean TN was greater in the mid-lake sites than any other sites. A great amount of TN in the mid-lake was most pronounced in monsoon 1994 because of an accumulated influence of the point sources during low inflow. Overall data suggest that concentrations of TN in this system did not show large differences along the longitudinal gradients and its distributions is likely determined by point-sources rather than inflow regime.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.469-485
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• 2004

The purpose of this study is to investigate the hydrochemical characteristics of groundwater in the Umsung area, and to elucidate the effect of host rock type, well depth and mineralization zone on the groundwater chemistry. The geology of the study area consists of Jurassic granite and Cretaceous sedimentary rocks, which are bounded by a fault. Most of shallow groundwaters exploited in the Jurassic granite area are used for agricultural purpose, whereas the deep groundwaters in the Cretaceous sedimentary rocks are used for a drinking water. The shallow groundwater shows weak acidic pH, the electrical conductivity ranging from $142\;to\;903\;{\mu}S/cm$, and the chemical type of $Ca-HCO_3\;to\;Ca-Cl(SO_4,\;NO_3)$. A few of shallow groundwaters are contaminated by nitrate, and show high concentration of Fe, Mn and Zn, that reflects the effect of a mineralization zone. The deep groundwater shows neutral to weak alkaline pH, higher electrical conductivity than that of shallow groundwater, and the chemical type of $Ca-HCO_3$. The seepage water from the abandoned mines does not have the characteristics such as acidic pH, high concentration of heavy metals and high sulfate content. The hydrogen and oxygen isotopes of groundwater indicates an altitude effect of the recharge area between deep groundwater and shallow groundwater. In conclusion, the chemical composition of groundwater complicately reflects the effects of their host rocks, well depth, agricultural activity and mineralization zone in the study area.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.12-25
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• 2017

In local underground mines heavily depending on the natural ventilation, ducted fan auxiliary ventilation system is strongly recommended instead of the total mine ventilation system requiring large capital and operating costs. Optimizing the installation of ducted fans in series in long large-opening mines is required to assure the economy and efficiency of the ventilation system. The two most critical design parameters for optimization are the wall separation distance and gap length between adjoining ducts. This study aims at deriving the optimal values for those two parameters concerning the economic and environmental aspects through the extensive CFD analysis, which minimizes pressure loss, leakage and entrainment of the contaminated air in the gap space. The ranges of the wall separation distance and gap length for study are selected by taking into consideration the existing recommendations and guidelines. The ultimate goal is to optimize the auxiliary ventilation system using ducted fans in series to provide a reliable and efficient solution to maintain clean and safe workplace environment in local long underground mines.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.11-17
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• 1996

Trichloroethylene(TCE) is the organic compound which is used variously at the industrial areas. It contaminates soils and groundwater by leaked storage tank, careless treatment in field and the effluent from waste landfills. This study was carried out to identify adsorptive behavior of TCE by soil. Batch experiments were conducted at different soil-organic matter content and lime treatment to determine Freundlich isothermal adsorption equation constant, k and n, for TCE. Sewage sludge cake was applied to make different soil-organic matter content with the level of Oton/ha(S1), 50ton/ha(S2), 100ton/ha(S3). Lime(calcium hydroxide) was treated with the level of 2ton/ha, 4ton/ha, 6ton/ha, 10ton/ha. Freundlich isothermal adsorption equations obtained from experiment with sewage sludge cake were as follows (on condition that the level of TCE applied to soil ranged from 0.5ng/g soil to 2.5 ng/g soil.) : S1 :x/m = 0.393 $C^2$, S2 : x/m = 0.436 $C^2$, S3 : x/m = 0.636 $C^2$Value of k was increased in higher order of 51, 52, 53 with increased level of sewage sludge cake application. From this results, soil which was applied higher level of sewage sludge cake had a good ability on TCE adsorption. With increased the level of lime application, pH of the soil was increased and the ability of the soil in TCE adsorption was decreased.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.132-132
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• 2000

환경오염과 이상기후의 영향으로 인한 수자원의 고갈과 함께 국내의 경우 수자원 개발 계획 및 수요량을 감안할 때 향후 7 년 내에 물부족 현상을 겪을 것이라는 보고가 있 었으며, 환경부담을 줄이기 위해 폐수의 배출기준은 강화되고 있다. 이러한 상황에서 제조 특성상 타 업종에 비해 폐수 발생량이 높은 편인 국내의 제지산업은 여러 해전부터 이에 대 한 방안을 모색하여 왔다. 일반적으로 폐수 수질 관리와 청수 사용량의 절감을 위해 고가의 폐수 처리 장치를 설치하거나 폐수 재활용을 통해 공정을 극도로 폐쇄화하는 방안으로 연구 가 진행되어 왔다. 이 중 용수의 재활용이 가장 경제적인 방법이지만, 재활용이 지속될수록 각종 무기염과 콜로이드성 유기물질이 축적되어 각종 약품의 효능 저하, 탈수속도의 저하 및 생산 제품의 품질 악화 등의 문제를 유발한다고 알려져 있다. 이를 해결하고자 하는 노 력으로 펄프 원료에 따른 공정수 내 용해성 물질의 분석과 재활용 횟수에 따른 각종 SS와 D DS의 축적 정도에 대한 기초 연구가 수행되었으며, 고폐쇄화된 공정에서 성능을 발휘할 수 있는 첨가제의 개발과 적용 방법에 대한 연구도 수행된 바 있다.여러 지종 가운데 골판지 원지는 용수의 재활용률이 상당히 높은 지종이기 때문에 공정수의 재활용이 진행될수록 열악한 저급 원료로부터 각종의 다양한 물질이 용출 혹은 배 출되며, 이러한‘물질은 골판지 원지의 강도 발현에 더욱 악영향을 미칠 것으로 판단되었다. 미세분으로 구성된 SS의 경우 이미 많은 연구를 통해 특성이 파악되었기 때문에 본 연구에 서는 ss를 제외한 공정수를 두 가지로 크게 나누어 고려하였다. 즉, ss로 측정되지 않지만 닥도를 유발할 수 있는 미세 무기물질과, 용해성의 무기염, 첨가제 및 추출물 둥으로 이루어 진 용해성 성분으로 나누어 분석하였으며, 또한 각각이 초지 특성에 미치는 영향을 살펴보 고자 하였다.을 해석코자 하였으며, 그 방법으 로 수치해석기법을 도입하였다. 또 실제 캘린더링 전후의 두께 변화를 측정하여 유리전이온도 의 도달 깊이와 비교하였다. 지필의 압축 정도는 롤의 직경과 닙 폭을 이용하여 MD 방향으 로 함수화하였으며, 열전달 계수로는 겉보기 값을 사용하였다. 이때 지펼은 균질한 것으로 가 정하였다. 함수율은 유리전이온도를 좌우하는 가장 큰 인자이나 본 연구에서는 항온항습처리 를 통해 유입지의 함수율을 고정시켰으며 캘린더링 시 함수율의 변이는 없다고 가정하였다. 그 결과 열침투깊이가 증가할수록 지필은 보다 변형되기 쉬운 상태가 되어 주어진 압력 조건에 대해 소성변형 정도가 증가하는 것으로 나타났다. 이는 캘린더링 전후에 두께 변화를 측정하여 정량적으로 평가할 수 있었다. 수치해석기법을 통해 같은 압력 조건에서 온도가 증 가함에 따라 혹은 같은 온도 조건에서 압력이 증가함에 따라 지필 내의 유리전이온도의 침투 깊이가 증가함을 알 수 있었으며 이는 캘린더링 전후의 두께 변화의 측정 결과와 일치하였 다. 또 NRT가 증가함에 따라서도 유리전이온도 침투 깊이가 증가하였다.합편에 비해 일부 우수한 양상을 보였지만 본 실험의 범위내에서는 통계적 정량적 차이를 제시할 수는 없었다. 향후 보다 광범위한 동물 실험이 필요할 것으로 사료된다.된다.하고도 완전교정술 도달 확률이 높은 치료전략이라는 사실을 입증하였으며 주대동맥폐동맥혈관부행지의 크기나 숫자가 단일화하기 쉬운 형태학적 특징을 지닌 경우에는 조기에 일단계완전교정술을 시행하여 양호한 결과를 얻을 수 있다는 사실을 발견하였다. 반면 본 환아군 중 단일화술을 먼저 시도한 군에서는 비록 단계적인 단일화를 시도한 군에서 단일화술과 관계된 수술사망율이 약간 낮기는 하였으나 완전교정술까지 완료될 가능성에는 차이가 없었다. 그러나 이 경우 보다 정련된 적응 환자의 선택을 통한 단일화 우선전략의 시도와 장기 추

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1432-1438
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• 1998

The gamma-radiation sensitivity of eight kinds of pathogenic bacteria related to beef was investigated in frozen cells $(-18^{\circ}C)$ with 0.1 M phosphate buffer and inoculated cells in beef. In frozen cells, D10 values of pathogenic bacteria related to beef were $0.07{\sim}0.69$ kGy, and inactivation factors were $2.90{\sim}42.86$ at the radiation doses of $2{\sim}3$ kGy. Beef was inoculated with Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Enterobacter aerogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Listeria monocytogenes, and Aeromonas hydrophila. Inoculated beef samples were packaged in air and irradiated at 0.005 to 3.0 kGy. Ninety percent of the viable pathogenic bacteria in beef was eliminated by doses of $0.1{\sim}0.61$ kGy at room temperature, and the inactivation factors were $3.28{\sim}30.0$ kGy at the radiation doses of $2{\sim}3$ kGy. Therefore, irradiation is considered to be an effective method to control pathogenic bacteria in beef.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.514-525
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• 2002

The analysis of heavy metals associated with both PM2.5 and PM10 fraction of aerosols was made from a northeast region of Seoul during the spring period of 2001. The mean concentrations of fine (PM2.5), coarse (PM10-PM2.5), and PM10 fraction were observed as 49.3${\pm}$29.2, 50.5${\pm}$35.0, and 95.5${\pm}$46.1 ${\mu}g$/m$^3$, respectively during this study period. According to the results of enrichment factor (EF) analysis between different particle fractions, major elements (including Fe, Ca, Na, and K) were found to exhibit EF values of less than 10. However, heavy metal components (like Zn and Pb) showed very high EF values. Comparison of fine/coarse (F/C) concentration ratio showed that Zn, Cr, Pb, and Ni have higher ratio values than others. The metallic composition of particles was also compared on both absolute and relative terms. The results of our analysis showed an evidence that the increase in the total metallic contents is prominent during the spring period due mostly to the Asian Dust event.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.381-386
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• 2012

This study was carried out to clarify the turbidity change on three stands (Castanea crenata, Pinus densiflora and Plantation Land) by rainfall characteristics in small watershed. The change of turbidity showed in order of plantation land, Castanea stand and Pinus stand. The linear equations models between turbidity and rainfall intensity were able to account for 91% in Castanea stand, 80% in Pinus stand and 71% in plantation land. The linear equations models between turbidity and duration of rainfall were able to account for about 0-1% in three stands. The linear equations models between turbidity and preceding dry days were able to account for about 30% in three stands. The linear equations models between turbidity and accumulative rainfall were able to account for about 6-22% in three stands. The results indicates that soil runoff by land use and development of forest area could be applied to the mitigation measures such as afforestation and erosion check dam for erosion control and water quality management in small watershed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.167-175
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• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.