• Journal of Korea Water Resources Association
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• v.37 no.12
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• pp.1065-1074
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• 2004

This study aims at the introduction of new catchment shape descriptor, developed by Moussa(2003), based on equivalent ellipse and the assessment of its hydrologic applicability. Two descriptors a+b and a+b+${\varepsilon}OM$were correlated to the lag time and those were applied to the estimation of representative values of Nash model parameters. They are applied in order to examine the practicality to 3 catchments in Korea, catchments in Korea, respectively, i.e. Pyeongchanggang catchment in Han river, Bocheongcheon catchment in Geum river and Wicheon catchment in Nakdong river. As a result both of two descriptors show higher correlations to the lag lime than classical geomorphologic factors and hereby Moussa's suggestion(2003) is confirmed. For the sake of simplicity the former is recommended. Also representative IUHs derived from this study show consistent basin response characteristics. It is desirable to conduct further more case studies on many other basins.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.943-947
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• 2010

Runoff ratio of paddy fields for the application of Event Mean Concentration (EMC) method was studied. To measure actual runoff ratio of paddy fields, a field monitoring was conducted for 2008 ~ 2009 period. Long-term rainfall data of four cities in major river basins were analyzed and weighting factors were developed to consider temporal and spatial variation of rainfall distribution of Korean peninsula. The observed runoff ratio ranged 0.00 ~ 1.20 and arithmetic mean were 0.25, respectively. However, the representative runoff ratio for paddy fields was determined as 0.41 according to the method suggested by National Institute of Environmental Research (NIER).

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1081-1091
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• 2012

SWAT model is applied to simulate rainfall-runoff and pollutant loadings in the Nakdong River basin as the condition for extreme droughts and floods. The year 1994 and 2002 are chosen as the drought and flood year, respectively, through the analysis of past rainfall data for 30 years. The simulation results show decreases in both runoff and pollutant loadings for the drought year but increases for the flood year. However, the pollutant loadings on some upper sub-basins increase for drought year due to highly-regulated dam discharge and soil moisture change. Collectively, extreme droughts and floods have negative impacts on water quality, showing elevated SS loadings during wet season and concentrated T-P concentrations during low flow season. The extent of these impacts is highly influenced by antecedent dry days and precipitation patterns.

• Journal of Environmental Impact Assessment
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• v.26 no.1
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• pp.57-67
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• 2017

Recently, Looking at the watershed management policy in Korea, It is preparing to manage sub-watershed and tributary from the government-led mainstream management, such as the selection of algae focused management tributary, application of tributary-TMDLs. At this point, this study is attempted to propose the residents participatory watershed management methods that is possible daily, voluntary and customized management in the sub-watershed. As a results, through this study, we found out the importance of sub-watershed unit based watershed management because of the pollutants in blind spot. It is the prerequisite for watershed management to arrange practicable bottom-up approach that these investigated contents can be reflected in the various planning.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.1-15
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• 2017

Eutrophication of surface waters is of concern worldwide, because it can result in many undesirable water-quality and ecological problems, such as hypoxic 'dead' zones and harmful algal blooms, both associated with considerable economic costs. In this study, we used LSM (Land Surface Model) to simulate nitrogen in five major rivers in the Southern Korean Peninsula. The main objective of this research was to enhance nitrogen data for input of LM3V model in South Korea. Input data for nitrogen fluxes were categorized into three sections including agriculture fertilizer, livestock manure, atmosphere deposition, biological fixation, and sewage pollutants were used as the nitrogen input. For using LM3V model, the nitrogen input data were regenerated by considering states of agriculture and industry in South Korea at a $1/8^{\circ}$ resolution. Then, we simulated stream/river flows and N loads throughout the entire drainage networks in South Korea at a $1/8^{\circ}$ resolution. By using the same parameters for the entire country ($100,210km^2$), composed of 5 river basins with varying climate and land use, the model simulates spatial (11 sites) and temporal (1999~2010) patterns of flows and nitrate-N loads are resonable by comparing observed flow and nitrate-N loads. The r (Pearson's linear correlation) for water temperature, flow and nitrate-N at river were 080~0.93, 0.62~0.92 and 0.5~0.9 respectively. Based on enhanced N input data and model results, we find that LM3V model as land surface model can be applied in South Korea with interaction of atmosphere and land conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.4
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• pp.42-52
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• 1985

This study was attempted to derivate empirical formulas for the runoff: ratio during ilood. season at three watersheds of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle, and lower portion of Nam Han river basin, respectively. Obtained formulas for flood runoff ratio can be applied as an element for the estimation, peak discharge for the design of various hydraulics structures which can be concidented with meteorological and topographical condition. The obtained through this study were analyzed as follows. 1.It was found that the magnitude of runoff ratio depends on the amount of rainfall for all studying basins. 2.Empirical formulas 'for the runoff' ratio were derivated as 1- 2,707 Rt0.345, 1-1.691 Rt0.242 and 1-1.807 Rt0.227 at Dan Yang, Chung Ju and Yeo Ju watershed, respectively. 3.The magnitude of runoff ratio was appeared in the order of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle and lower portion of Nam Han rivet basin, respectively. 4.It was assumed that in general the more it rains, the lesser becomes the ratio of loss rainfall. Especially, the ratio of loss rainfall for Dan Yang, upper portion of river basin was shown as the lowest among three watersheds. Besides, the magnitude of that was appeared in the order of Chung Ju and Yeo Ju watershed located at middle, and lower part of river basin, respectively. 5.Relative and standard errors of runoff ratio calculated by empirical formulas were shown to be within ten percent to the observed runoff ratio in all watersheds. 6.It is urgently essential that the effect of antecedent rainfall have an influence on the next coming flood should be studied in near future.

• Journal of Korean Society of Rural Planning
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• v.21 no.2
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• pp.127-135
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• 2015

In recent years, meteorological disasters have frequently occurred in rural areas. As a result, there have been growing concerns over the protective measures needed. In order to avoid natural risks and damage, and to strengthen countermeasure to meteorological disasters, local governments needs to be prepared. Therefore, this paper seeks to prevent meteorological disasters through mapping of inundation vulnerability in agricultural land, Chungcheongnam-do. In doing so, this study were considered 5 variables (i.e. precipitation, region of altitude below 50m, region of slope gradient is below 10 degree, distance from river within less 50m) for creating vulnerability map. The precipitation was excluded in five variables. Since, the precipitation which include Daily maximum precipitation, 2-Daily maximum precipitation, summer precipitation was not any correlation among them. The results of analysing four variables, exclusive of precipitation, were showed that the agricultural lands where located in Dangjin, Buyeo, Hongseong and Asan were low correlation of inundation vulnerability by overlapping analysis. Moreover, The correlation analysis was showed low correlation between each factors and the annual average area of agricultural lands' inundation, whereas, the correlation analysis which was overlapping each factor showed high correlation. In conclusion, in order to create reliable vulnerability map in agricultural lands, Chungcheongnam-do, it must be considered to overlap analysis of the four main factors such region of altitude below 50m, region of slope gradient is below 10 degree, distance from river within less 50m. We suppose that this study's analysis can help to set the preparedness site of agricultural lands inundation.

• Journal of Korea Water Resources Association
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• v.39 no.7 s.168
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• pp.617-626
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• 2006

In this study 3-month SPI data from 59 stations over the Korean peninsula are analyzed by deriving and spatially characterizing the EOFs. Also, the coefficient time series of EOF are applied to the multi-variate time series model to generate the time series of 10,000 years, to average them to estimate the areal average, and to decide the maximum drought severity for given return periods. Finally, the drought prevention ability is evaluated by considering the effective storage of dam within the basin and the size of agricultural area. Especially for the return period of 30 years, only the Han river basin has the potential to overcome the drought. Other river basins like the Youngsan river basin, which has a large portion of agricultural area but less water storage, are found to be very vulnerable to the rainfall-sensitive agricultural drought.

• Journal of Environmental Policy
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• v.11 no.4
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• pp.107-130
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• 2012

Economic analysis of climate change in the Korean peninsula has been conducted in the four major river basins. Although climate change impacts can vary in many terms, typically flood damages from the increase of precipitation and drought from rainless, this research only focused on effects of altering precipitation due to the lack of information and depth-damage functional form in Korea. This research also considered a gamma function of 5 % failure to deal with uncertainty issues in water resources. For the detailed analysis, time different discount rates have been used for short, mid, and long period, viz., 2.76%, 1.45%, and 0.62%, respectively. Over all effects of climate change on four major riverbasins can be summarized as no short period damage except the Han river basin. In the Han river basin, rapid increases of residential water use lead short term water shortage.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.351-358
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• 1992

The gravity measurement has been conducted at 327 station with an interval of 25 m along the survey lines of 1.6 km and 1.7 km traversing Hyungsan river and of 2.35 km and 2.42 km running N-S direction near Heunghae-eup in Pohang basin. Bouguer gravity anomalies were obtained, and geologic structure along four survey lines were interpreted by applying Fourier series and Talwani methods for two demensional body. A fault is in existence along the Hyungsan river, and northern block of it is displaced down by 150 m to 200 m relative to southern one. The thicknesses of Yeonil Group vary from 250 m to 550 m and from 150 m to 300 m in the northern and southern blocks of the fault, respectively. Another fault is in existence running E-W direction near Heunghae-eup, and its southern block is displaced down by about 250 m relative to its northern block. The thicknesses of Yeonil Group vary from 200 m to 400 m and from 500 m to 700 m in the southern and northern blocks of the fault, respectively. Above two faults are normal faults and make a graben structure, which results the age of rocks in the central region between the faults is younger than those of outside regions. This result coincides with that of paleontological study.