• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.60-67
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• 2014

In this study, four methods for calculation of continuous daily flow was suggested using short-term or partial recording station of streamflow including missing data. Using these methods, standard flows at the outlet of unit/small basins for the management of total maximum daily loads (TMDLs) in Namgang dam basin were estimated from full-period flow duration curve (FDC). Four methods of extension are described, and their properties are explored. The methods are regression (REG), regression plus noise (RPN), and maintenance of variance extension types 1 and 2 (MOVE.1, MOVE.2). In these methods, the continuous daily flow was calculated using extension equation based on correlation analysis, after conducting the correlation analysis between historic record of streamflow and long-term recording station (a base station). Finally the best optimal method was selected as the MOVE.2, and the standard flows in the abundant, ordinary, low and drought flow estimated from FDC was evaluated using MOVE.2 in unit/small basins.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.1
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• pp.23-32
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• 2003

The objective of this study is assessing water management efficiency using water withdrawals from rivers and water requirements for paddies. The water management efficiency was defined by the ratio of water requirements and water withdrawals. Water withdrawals were estimated using the operating times and pumping capacity of the pumping stations from 1992 to 1999 in the Han River and Nakdong River basins. Water requirements were estimated by adding the evapotranspiration of the crops and infiltrations in the irrigated area. Evapotranspiration from the paddies was calculated by the FAO modified Penman method with observed daily weather data. The monthly water management efficiency was analyzed for each pumping stations and the district offices of KARICO (Korea Agricultural and Rural Infrastructure Corporation). The efficiencies of 59 pumping stations in the Han River basin varied from 19% to 135%, and the average was 61%. The efficiencies of 146 pumping stations in the Nakdong River basin ranged from 17% to 190%, and the average was 72%. There were no good correlations between the water management efficiency and pump capacity or irrigated area, it showed that the water management efficiency was affected by the traditional water management practices rather than the scale of irrigation district.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.976-976
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• 2012

The applicability of a distributed rainfall-runoff model for large river basin flood forecasts is analyzed by applying the model to the Nakdong River basin. The spatially explicit hydrologic model was constructed and calibrated by the several storm events. The assimilation of the large scale Nakdong River basin were conducted by calibrating the sub-basin channel outflow, dam discharge in the basin rainfall-runoff model. The applicability of automatic and semi-automatic calibration methods was analyzed for real time calibrations. Further an ensemble distributed rainfall runoff model has been developed to measure the runoff hydrograph generated for any temporally-spatially varied rainfall events, also the runoff of basin can be forecast at any location as well. The results of distributed rainfall-runoff model are very useful for flood managements on the large scale basins. That offer facile, realistic management method for the avoiding the potential flooding impacts and provide a reference for the construct and developing of flood control facilities.

• Journal of Environmental Science International
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• v.24 no.8
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• pp.1085-1099
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• 2015

The purposes of this study were to suggest the methodology to select prior areas in the environmental pollution survey for livestock excreta (EPSLE) as well as to elucidate the validity of the methodology. In this study, the prior areas in the EPSLE were determined by examining the number of compost facilities categorized according to the three levels of size including the basin, the sub-basin and the watershed, respectively, based on the data from "Annual Nation-wide Pollution Sources Survey (2012)". The results suggested that the list of prior basins were Nakdong, Geum, Youngsan and Han river basins in order. Also, it was examined that the prior sub-basins in the four river basins including Nakdong, Geum, Youngsan and Han rivers were Naesung Stream, Geumgang Gongju, Juam Dam and Namhan Downstream, respectively. The prior watersheds in the sub-basins of Naesung stream, Geumgang Gongju, Juam Dam and Namhan Downstream were Seocheon Downstream, Geum Stream, Gyeombaek Suwipyo and Yanghwa Stream, respectively. The validity of the methodology used in this study was elucidated by analyzing the correlation of the number of compost facilities with the concentrations of T-N and T-P observed in the end-points of sub-basins. The results of correlation analysis showed that the concentrations of T-N and T-P increased with the number of compost facilities. Specifically, there was the stronger correlation between the number of compost facilities and the concentrations of T-N than that for T-P. Consequently, it was proved that the methodology used in this work was valid and rational for the selection of prior areas in environmental pollution survey for EPSLE.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.266-271
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• 2005

In this study, following works have been carried out : division of Nakdong River Basin into 25 sub basins, development of a technique to evaluate spatial distribution of rainfall and analysis of rainfall data of 169 stations, selection of control points, and selection of a hydrologic model(SSARR). The runoff analysis showed that the surface-subsurface separation and soil moisture index parameters are the most important two to the simulation result.

• Journal of Korea Water Resources Association
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• v.31 no.4
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• pp.483-490
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• 1998

The possibility of water transfer from Han river basin to Nakdong river basin by connecting them is studied as an alternative to solve water shortage problem in Nakdong river basin. After estimating the amount of water shortage from Nakdong river basin, the amount of water surplus from Han river basin is estimated by using simulation and optimization techniques. HEC-5 is used to study small to medium size reservoirs as a simulation technique and dynamic programming is used to study multi-purpose reserviors as an optimization technique. Also, the cost of the interbasin water transfer from Han river basin to Nakdong river basin is also compared with that of constructing new reserviors in Nakdong river basin. If new reservoirs are constructed in Nakdong river basin as planned, water supply can satisfy various water demands until 2021 without the interbasin water transfer. In economic point of view, constructing new reserviors has an advantage over the interbasin water transfer.

• Journal of Environmental Science International
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• v.20 no.3
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• pp.373-384
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• 2011

This study aims at the examination of the relative characteristics of discharge and water quality in river basins using statistical methods. For it, water quality and discharge data was collected in observed stations of Nakdong river and carried out correlation analysis, regression analysis, factor analysis and cluster analysis. And it was investigated the applicability of water quality prediction using Nearest-neighbor method. As a result, it grasped a trenditional characteristics and mutual relations between discharge an water quality data. Therefore, this results were suggested the comprehensive data and methods for a management of water quality, effective operation and policy development in Nakdong river basin.

• The Korean Journal of Ecology
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• v.6 no.2
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• pp.81-89
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• 1983

The change of environmental factors with flow rates were studied quantitatively for two rivers, the Nakdong River and the Sin stream, which have different basins in ecosystem structures, during short period after a heavy rain. In the Nakdong River, transparency, DO, alkalinity and hardness were negatively correlated with the flow rate by logarithmic function, but the concentration of SiO2 was relatively constant regardless of the flow chage. In the Sin stream, transparency, alkalinity, hardness and the concentration of NH3-N, NO2-N and SO4= showed negative correlation with the flow rate by logarithmic function. The ratios of maximum to minimum values for aquatic environmental factors during the samller than that for flow rate in the respective rivers (28 in the Nakdong R.; 50 in the Sin S.). Immediately after the heavy rain, the concentrations of NO2-N, NH3-N and PO4-P in the Sin stream were 8, 6 and 1 times as high as those in the Nakdong River, respectively, but in the stable flow state, those became 94, 25 and more than 10 times, respectively. The load for most of the dissolved environmental constituents changed similarly to the flow rate in both rivers. It is notable that, at the stable flow state, the loads for NH3-N (59g/sec) and NO2-N (3.3g/sec) in the Sin stream were 4.3 and 1.3 times as high as those in the Nakdong River.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.51-59
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• 1999

This study aims at the development of the techniques for the rainfall forecasting in river basins by applying neural network theory and compared with results of Multivariate Model (MVM). This study forecasts rainfall and compares with a observed values in the San Chung gauging stations of Nakdong river basin for the rainfall forecasting of river basin by proposed Neural Network Model(NNM). For it, a multi-layer Neural Network is constructed to forecast rainfall. The neural network learns continuous-valued input and output data. The result of rainfall forecasting by the Neural Network Model is superior to the results of Multivariate Model for rainfall forecasting in the river basin. So I think that the Neural Network Model is able to be much more reliable in the rainfall forecasting.

• Journal of Korea Water Resources Association
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• v.49 no.3
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• pp.177-186
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• 2016

Drought is a water-related natural disaster which can be simply described as spatially and temporally sequential absence of water. However, its characteristics are very difficult to define. For this reason, the preparation and mitigation from drought events have not been successful. In the current study, we illustrated a design drought estimation approach of water resources infrastructures as well as the existing theoretical one to prepare and mitigate drought disasters. Theoretical and simulation methods were tested including three time series models such as autoregressive (AR), Gamma AR, Copula AR models. The results indicated that for South Korea region, the simulation-based method to estimate drought frequency presented better performance and all the three time series models show similar performance to each other. The current drought event occurring in South Korea was investigated with dividing South Korea into four basins as Han River, Nakdong River, Geum River, and Nakdong River basins. The results showed that two middle and north basins presented significant drought events with 3 year drought duration and around 40 year return period while the other two southern regions illustrated relatively weaker drought events.