• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.425-428
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• 2002

This study has been carried out to analized of long term changes of water quality with regard to main pollutant sources in agricultural reservoirs on the basis of data during 1996-2001. The major source was domestic wastewater(DWW) and water pollution by non-point sources(NPS) is increasing as time goes. It was determined that Seasonly average values of DWW were pH $7.6{\sim}8.7$, COD $7.0{\sim}9.4$, T-N $0.74{\sim}2.07$, T-P $0.05{\sim}0.62$, Live-stock wastewater(LWW) were pH $7.5{\sim}8.9$, COD $5.5{\sim}9.8$, T-N $0.57{\sim}1.91$, T-P $0.04{\sim}0.13$, NPS were pH $7.1{\sim}8.3$, COD $3.1{\sim}5.2$, T-N $0.29{\sim}1.44$, T-P $0.02{\sim}0.07$. Fluctuation of DWW and LWW were very wide and variable long term patterns of them were similar. Trophic states by Carlson Index of DWW and LWW was classified as eutrophic to hypretrophic from chl-a, T-P concentration.

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.370-374
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• 2000

At this study, the monitoring network of water quality was established in the agricultural watershed an area 14,960 ha of the central southwest of Korea. Loads of nitrogen and phosphorus by agricultural land use were quantified bases on total amounts of stream flow. The land were used as a lowland paddy, an upland and a forest about 12.14 % (1,815 ha), 5.17 % (773 ha) and 80.31 % (12,015 ha) of the area, respectively. For six months, from May 1 to October 31, 1999, the total precipitation was 970 mm and the total amount of stream flow was $80,281,000\;m^3$. In the load of agricultural non-point sources relevant to land use, total-N was 138,413 kg, then ammonia-N 13,362 kg, nitrate-N 124,629 kg, and total-P 157 kg. The loss of nutrient which from application of chemical fertilizer were 38.0% in nitrogen and 0.1% in phosphorus to input chemical fertilizer in the watershed.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.3
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• pp.63-68
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• 2007

The LRA(Logistic Regression Analysis) conducts a quantitative analysis by collecting a lot of samples and the AHP(Analytic Hierarchy Program) makes use of expert decision influenced by subjective judgment to a certain degree. This study is to suggest a combination method in mapping landslide hazard by giving equal weight for the result of LRA and AHP. Topographic factors(slope, aspect, elevation), soil dram, soil depth and land use were adopted to classify landslide hazard areas. The three methods(LRA, AHP, the combined approach) was applied to a $520km^2$ region located in the middle of South Korea which have occurred 39 landslides during 1999 and 2003. The suggested method showed 58.9% matching rate for the real landslide sites comparing with the classified areas of high-risk landslide While LRA and AHP Showed 46.1% and 48.7% matching rates respectively. Further studies are recommended to find the optimal combining weight of LRA and AHP with more landslide data.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.121-128
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• 2011

Long-term water treatment performance analysis was conducted for the constructed wetland treating agricultural tailwater. Studied wetland was established in 2001 and operated from June, 2002 to November, 2010. Wetland vegetation cover was shown over 90 % coverage after 2005. According to vegetation development, accumulation of sediment nutrient was observed; Organic Carbon, T-P and T-N. In addition, DO concentration and temperature was decreased in the constructed wetland output. An infiltration rate also significantly decreased due to compaction of wetland soil. A runoff coefficient was increased due to the low infiltration rate after 2005. A T-N, TSS and Chl.a removal rate was maintained constantly. However, the T-P removal rate was slightly decreased along to wetland operation because low DO concentration could increase elution of phosphorus from sediment. After constructing open water, the T-P removal rate was increased. This is because open water could accelerate the reaearation process. Consequently, over three years of vegetation development could be helpful for wetland performance. In addition, DO concentration is important factor to maintain the T-P treatment.

• KCID journal
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• v.18 no.2
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• pp.3-14
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• 2011

Increased impervious surfaces alter stream hydrology resulting in lower flows during droughts and higher peak flows during floods. Not only urban area but also rural area has been expanded impervious surfaces because of increasing of greenhouses. The main objective of this study was to evaluate the performance of the AnnAGNPS (Annualized Non-Point Source Pollution Model) on the surface runoff characteristics of the Daejeon-Stream watershed, and to predict the hydrological effects due to increasing of impervious surfaces. The model parameters were obtained from the geographical information system (GIS) databases, and additional parameters calibrated with the observed data. The model was calibrated by using 2004 of the runoff data and validated by using 2002 data obtained from WAMIS (Water Management Information System) to compare the simulated results for the study watershed. R2 values and efficiency index (EI) between observed and simulated runoff were 0.78 and 0.80, respectively at the calibration period. In this study, expanding of impervious surfaces such as greenhouses caused increasing of surface runoff, but caused decreasing of total nitrogen and total phosphorus loads.

• Proceedings of the KSRS Conference
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• v.2
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• pp.647-650
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• 2006

Compact Airborne Spectrographic Imager (CASI) hyperspectral imagery was acquired over the Little Miami River Watershed (1756 square miles) in Ohio, U.S.A., which is one of the largest hyperspectral image acquisition. For the development of a 4m-resolution land cover dataset, a hierarchical approach was employed using two different classification algorithms: 'Image Object Segmentation' for level-1 and 'Spectral Angle Mapper' for level-2. This classification scheme was developed to overcome the spectral inseparability of urban and rural features and to deal with radiometric distortions due to cross-track illumination. The land cover class members were lentic, lotic, forest, corn, soybean, wheat, dry herbaceous, grass, urban barren, rural barren, urban/built, and unclassified. The final phase of processing was completed after an extensive Quality Assurance and Quality Control (QA/QC) phase. With respect to the eleven land cover class members, the overall accuracy with a total of 902 reference points was 83.9% at 4m resolution. The dataset is available for public research, and applications of this product will represent an improvement over more commonly utilized data of coarser spatial resolution such as National Land Cover Data (NLCD).

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.237-242
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• 2017

Along with effluence of non-point pollution source, continuous precipitation due to rainy season or localized heavy rain can also be a good reason for increase of flow rate. And if the water level is going up due to the increase, floating debris around rivers and streams will move because of increased flow velocity. However, currently, there are no studies which perform quantitative calculation on movement of floating debris by analyzing amount of rainfall and flow rate in both domestic and abroad. Thus, the present study calculated amount of movement of floating debris based on moving route monitoring results according to changes of effective rainfall and flow rate that are obtained by using SCS-CN method.

• Advances in concrete construction
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• v.5 no.2
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• pp.145-154
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• 2017

In the present day scenario, concrete construction is rapidly becoming uneconomical and non sustainable practice, due to the scarcity of raw materials and environmental pollution caused by the manufacturing of cement. In this study an attempt has been made to propose recycled aggregates from demolition wastes as coarse aggregate in geopolymer concrete (GPC). Experimental investigations have been conducted to find optimum percentage of recycled aggregates (RA) in GPC by replacing 20%, 30%, 40%, 50% and 60% of coarse aggregates by RA to produce recycled aggregate geopolymer concrete (RGPC). From the study it has been found that the optimum replacement percentage of recycled aggregates was 40% based on mechanical properties and workability. In order to study and compare the flexural behaviour of RGPC and GPC four beams of size $175mm{\times}150mm{\times}1200mm$ were prepared and tested under two point loading. Test results were evaluated with respect to first crack load, ultimate load, load-deflection characteristics, ductility and energy absorption characteristics. Form the experimental study it can be concluded that the addition of recycled aggregate in GPC causes slight reduction in its strength and ductility. Since the percentage reduction in strength and behaviour of RGPC is meager compared to GPC it can be recommended as a sustainable and environment friendly construction material.

• Journal of Environmental Health Sciences
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• v.31 no.6
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• pp.467-474
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• 2005

The runoff characteristics of combined sewer overflow(CSO) in the urban area of Jeonju were investigated and analyzed by using the SWMM (Storm Water Management Model) and GIS. From August to November 2004, investigations on two rainfall events were performed and flowrate, pH, BOD, COD, SS, T-N and T-P were measured. these data were used for model calibration. Using GIS technique, watershed characteristics of study area were calculated. that is, divide into sub_basin, total width, slope, make soil map etc. On the basis of the measured data and the simulation results by SWMM, it could be known that the $80-90\%$ of pollution load are discharged in early-stage storm runoff. SMC(site mean Concentration) for combined sewer system area were BOD 28.1, COD 31.5, SS 186 ppm etc. this is shown that during the rain fall, high concentration of waste was loaded to receiving water. Unit loads of combined sewer system area were BOD 306, COD 410, SS 789, T-N 79, T-P 6.8 kg/ha/yr.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.475-475
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• 2011

우리나라 토지계 비점오염부하에서 농촌계 발생오염부하 비중은 질소와 인이 가각 74%와 55%로 보고되고 있다. 이러한 농촌계 오염부하에서 저수지 관개논에서의 오염부하 비중은 질소와 인이 각각 29%와 44%이며, 전체 논 대비 저수지 관개논 비중은 45%에 달하고 있다. 따라서 하천 및 호소의 수질향상을 위해서는 저수지 관개논의 비점오염배출에 대한 효과적/체계적인 관리가 필요하다. 본 연구의 목적은 저수지 관개논에서의 비점오염부하를 정량화하기 위하여, 저수지 관개논 비점오염부하 모니터링 기법 정립 및 계측시스템을 구축하고, 비점오염부하의 종합적인 모니터링을 통하여 비점오염원 주요 관리인자의 상호관련성을 정량적으로 분석/평가하는 데 있다. 대상지구는 이동저수지 하류에 위치한 관개논을 선정하고, 수문수질 계측망을 구성하였다. 강수량, 증발산량, 담수심, 침투수량, 관개수량, 배수량 등의 수문/수질인자와 토양 인자 및 작물생육특성 등에 대한 모니터링을 통하여 관개논에서의 비점오염부하를 정량적으로 산정하였다. 이를 바탕으로 각각의 비점오염부하에 영향을 미치는 주요 인자 상호 관련성을 정량적으로 평가하였다. 본 연구는 현재 초기 연구에 해당되며 향후 지속적인 모니터링 및 정량적 평가가 이루어져야 하며, 농업비점오염에 의한 수체에 미치는 영향을 분석함으로서 지속가능한 농업, 수계의 수질보전대책 수립, 그리고 물환경 정책 도출 및 수립에 활용이 가능할 것으로 기대된다.