• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.157-170
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• 2013

In this study, flood runoff characteristics is analyzed according to subbasin divisions by physically based rainfall-runoff model and appropriate number of subbasin divisions is suggested for midsize test basins. The Clark method, a lumped model in HEC-HMS, and the ModClark method, a semi-distributed model are used to simulate rainfall-runoff processes on Andong-reservoir basin, Imha-reservoir basin, and Pyeongchang river basin. The test basins were divided into nine subdivision cases by equal-area subdivision method such as single basin, 3, 5, 6, 7, 9, 10, 12, and 15 subbasins, and compared the simulated and observed values in terms of the peak flow and the peak time. The simulation results indicated that the peak flows tended to increase and the peak time shifted earlier as the number of subdivisions increased and this tendency weakened after the certain number of subdivisions. In this research, the specific number of subdivision was defined as the minimum number of subdivision considering both peak flow and peak time. Consequently, the minimum number of subdivisions is determined as 5 for Andong and Imha reservoir basins and 7 for Pyeongchang river basin.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.891-906
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• 2014

This study suggests the hedging rule of MIP (Mixed Integer Programing) in counting the risk evaluation criteria of the objective function and constraints in order to provide the optimum operating rule in reservoir system as constraining water shortage as much as possible which may happen in the downstream control point of water supply in the aspect of water system management. The proposed model is applied to the Han-river reservoir system for two testing periods (Case I: Jan. 1993~Dec. 1997, Case II: Jan. 1999~Dec. 2003). The model based on the hedging rule with trigger volume, estimated in this study shows that in Case I, the monthly minimum discharge was $310.6{\times}10^6m^3$ in the single operation, $56.3{\times}10^6m^3$ in the joint operation, and $317.5{\times}10^6m^3$ in the hedging rule and also, in Case II, the monthly minimum discharge was found to be $204.2{\times}10^6m^3$ in the single operation, $111.2{\times}10^6m^3$ in the joint operation, and $243.7{\times}10^6m^3$ in the hedging rule. In conclusion, the hedging rule, proposed in this study can decrease vulnerability while guarantees reliability and resiliency.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.969-982
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• 2008

As hydrological models have been progressively developed, they are recognized as appropriate tools to manage water resources. Especially, the need to evaluate the effects of landuse and climate change on hydrological phenomena has been increased, which requires powerful validation methods for the hydrological models to be employed. As measured streamflow data at many locations may not be available, or include significant errors in application of hydrological models, streamflow data simulated by models only might be used to conduct hydrological analysis. In many cases, reducing errors in model simulations requires a powerful model validation method. In this research, we demonstrated a validation methodology of SWAT model using observed flow in two basins with different physical characteristics. First, we selected two basins, Gap-cheon basin and Yongdam basin located in the Guem River Basin, showing different hydrological characteristics. Next, the methodology developed to estimate parameter values for the Gap-cheon basin was applied for estimating those for the Yongdam basin without calibration a priori, and sought for validation of the SWAT. Application result with SWAT for Yongdam basin showed $R_{eff}$ ranging from 0.49 to 0.85, and $R^{2}$ from 0.49 to 0.84. As well, comparison of predicted flow and measured flow in each subbasin showed reasonable agreement. Furthermore, the model reproduced the whole trends of measured total flow and low flow, though peak flows were rather underestimated. The results of this study suggest that SWAT can be applied for predicting effects of future climate and landuse changes on flow variability in river basins. However, additional studies are recommended to further verify the validity of the mixed method in other river basins.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.737-751
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• 2002

Water quality in Daechung Lake was predicted for various discharge conditions of Yongdam dam. The same scenarios were applied as in the previous paper by the authors for Keum River water quality modeling. Effects in water quality due to changes in discharge conditions from Yongdam Dam were less distinct to the Daechung Lake than to the inflowing Keum River due to sink processes in the lake. For the minimum flow year, it is appropriate to maintain Yongdam dam discharge rate to 8.9 $m^3$/sec considering the current field conditions and future predictions of TN and TP concentrations of Yongdam dam. Effect of Yongdam dam discharge conditions to the Daechung Lake water quality were stronger for drier years. However it should be noted that the effects were dependent upon the water quality of Yongdam discharge at the same time. Therefore, water quality management effort should be emphasized before the discussion over the discharge volume of Yongdam dam. The input data sets for simulations in this study were formulated using the available data and assumptions based on authors experiences for the fields. Therefore, continued data collection effort will ensure the validity of this study.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.375-375
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• 2015

최근 도시화에 따른 도로구역의 증가는 도심지의 불투수면적의 확대 및 도로의 수로화를 야기하여 집중호우 발생 시 노면 및 저지대의 침수를 가중시키고 있으며, 이로 인한 인명피해 및 재산 피해는 점차 증가하는 추세이다. 이에 기후변화에 따른 강우량의 변화 및 국지성 집중호우 등을 고려하고 도심지 침수 방지 및 방재성능 강화를 위하여 과거에 간선 10년, 지선 5년에서 간선 30년, 지선 10년으로 관거의 설계빈도가 상향조정 되었다. 도심지의 도로 및 유역 유출량의 배수에 상당한 영향을 미치는 빗물받이 및 빗물받이 유입구는 도심지의 방재성능강화 목적에 맞는 설계가 이루어져야 하나 현재 국내의 빗물받이 설치기준은 하수도시설기준(2009, 환경부)에서 '빗물받이 크기별, 도로 차선별 적정 빗물받이 설치간격' 으로 설계빈도 5년을 반영하여 제시된 설치기준이므로 이에 대한 수정 및 개정이 필요한 실정이다. 이에 본 연구에서는 관거시설의 설계빈도 상향을 고려한 도로 빗물받이의 유입량 산정을 위해 빗물받이 유입구 크기별 유입량을 도로의 차선, 종경사, 측구 횡경사 및 설계빈도의 변화를 고려하여 도로에서의 유출량을 산정하였으며, Froude 상사법칙을 이용하여 수리실험모형을 제작하여 실험을 실시하였다. 빗물받이 제원은 현재 대부분의 국도에 설치되는 크기인 $40{\times}50cm$, $40{\times}100cm$ 및 $40{\times}150cm$를 축소 제작하였다. 측구의 유량은 도로의 차선(2~4차선), 경사(도로 종경사 2~10%, 측구 횡경사 2~10%) 및 설계빈도(최대 30년)을 고려하였다. 실험 결과 측구의 횡경사가 커질수록 빗물받이로 유입되는 유량은 증가하였으며, 빗물받이 유입부의 길이가 증가함에 따라 유입부 측면부를 통한 횡유입량을 증가시켜 빗물받이 유입부의 차집율을 증가시켰다. 또한, 도로의 조건 변화 및 유입량의 변화에 따라서 흐름폭이 감소할수록 차집율이 증가하였다. 수리실험결과를 토대로 도로의 조건변화(차선, 도로 종경사, 측구 횡경사) 및 설계빈도 변화를 고려한 빗물받이의 차집율을 제시하였고 이를 회귀분석 하여 빗물받이 유입구 크기별 유입량 산정식을 도출하였다. 이는 설계빈도 상향에 따른 국내 빗물받이 유입부의 설계 기준 제시에 기초자료로 활용이 가능할 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.409-418
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• 2019

Debris flows occur in mountainous areas due to heavy rains resulting from climate change and result in disasters in the downstream area. The purpose of this study is to estimate the impact force of a debris flow when a check dam according is installed in various locations in the channel of a highly mountainous area. A Finite Differential Element Method (FDM) model was used to simulate the erosion and deposition based on the equation for the mass conservation and momentum conservation while considering the continuity of the fluid. The peak impact force from the debris flow occurred at 0 to 5 sec and 15 to 20 sec. When the supplied water discharge was increased, greater peak impact force was generated at 16 to 19 sec. This means that when increasing the water supply, the velocity of the debris flow became faster, which results in increased energy of the consolidation between the particles of the water and the sediment made. If a number of check dams were to be set up, it would be necessary to investigate the impact force at each location of the check dam. The results of this study could provide useful information in predicting the impact force of the debris flow and in installing the check dams in appropriate locations.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.541-552
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• 2018

The implementation of drought measures in the upstream areas of river basins is seldom considered with respect to water supply. However, the demand for such measures is increasing rapidly owing to the occurrence of severe droughts, and interventions on streams and the water supply are needed. Physical interventions are an option to prevent streams from becoming dry and to maintain stream water flow, but dam construction is challenging because of environmental and ecological considerations. Here, a feasibility study was conducted to assess the potential effects of sand dams, which are widely used in arid regions in Africa. The SWAT-K model, which is a hydrologic model used for Korean watersheds, is used to estimate the flow rate of water in an ungauged watershed. The changes in water storage of the sand-dammed reservoir and in downstream flow rates are estimated for two types of sand dam (natural and dredged). The results show that sand dams are capable of increasing the downstream flow rate during normal conditions and of mitigating water supply problems caused by the withdrawal of water during drought periods.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.75-84
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• 2023

Many developing countries face challenges in estimating long-term discharge due to the lack of hydrological data for water supply planning, making it difficult to establish a rational water supply plan for decision-making on water distribution. The study area, the Bandung region in Indonesia, is experiencing rapid urbanization and population concentration, leading to a severe shortage of freshwater. The absence of water reservoir prediction methods has resulted in a water supply rate of approximately 20%. In this study, we aimed to propose an approach for predicting water reservoirs in developing countries by analyzing water safety and potential water supply using the MODSIM (Modified SIMYLD) network model. To assess the suitability of the MODSIM model, we applied the unit hydrograph method to calculate long-term discharge based on 19 years of discharge data (2002-2020) from the Pataruman observation station. The analysis confirmed alignment with the existing monthly optimal operation curve. The analysis of power plant capacity revealed a difference of approximately 0.30% to 0.50%, and the water intake safety at the Pataruman point showed 1.64% for Q95% flow and 0.47% for Q355 flow higher. Operational efficiency, compared to the existing reservoir optimal operation curve, was measured at around 1%, confirming the potential of using the MODSIM network model for water supply evaluation and the need for water supply facilities.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.63-68
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• 1993

Heat penetration characteristics of retort pouched curry were studied to determine optimal sterilization conditions. Heating curve of retort pouched curry showed a simple logarithmic curve. The $f_h$ value (min.) of solid part in retort pouched curry was 1 min. higher than that of liquid part. $f_h$ value (min.) and $j_h$ value (heating lag factor) ranged from 8.3 min. to 12 min. and 1.0 to 1.17 respectively with increasing the ratio of solid to liquid and viscosity. $f_h$ value (min.) and $j_h$ value were significantly increased from 7.4 min. to 12.6 min. and 1.0 to 1.14 respectively with increasing thickness of the pouch from 11 to 15 mm. The low and medium volatile aroma components of retort pouched curry decreased during sterilization, which increased the high volatile aroma components. The retort pouched curry processed at $120^{\circ}C$, for 24 min. with $F_o$, value of $8{\sim}9$ could keep up a desirable quality without any remarkable deterioration.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.250-254
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• 2009

상수관망의 기능은 정수처리 된 양질의 물을 수용가에게 안전하게 공급하는 것이며, 이를 위해 상수관내에는 수용가에 충분한 양의 물을 공급할 수 있는 적정 유량과 압력이 유지되어야하고 최소기준치 이상의 잔류염소농도 유지 등의 적절한 수질을 만족시켜야한다. 하지만 상수관망은 상수관 파괴에 따른 오염물질 유입이나 테러와 같은 인위적인 오염물 주입 등의 갑작스런 사고에 의한 수질오염에 언제나 노출되어 있다. 이러한 수질오염사고 발생 시 신속한 대처를 위해서는 상수관망의 모든 절점에 수질측정 센서를 설치하는 것이 바람직하겠지만, 이는 경제적 측면과 센서의 유지 관리측면에서는 이상적이지 않다. 또한 발생 가능한 모든 상황에 대한 시뮬레이션 기반의 수질모델링을 통하여 적절한 수질오염 측정지점을 선정할 수도 있겠지만, 이는 상당한 시간과 계산능력을 요한다. 따라서 본 연구에서는 네트워크 분석기법 (Network Analysis)인 Betweenness Centrality와 수리해석 모형인 EPANET을 이용하여 상수관망의 수질오염측정지점 선정기법을 제안하였다. Betweenness Centrality는 네트워크를 구성하는 한 절점과 다른 한 절점을 연결시키는 특정 절점의 매개정도로 중심성을 측정하는 기법이다. Betweenness Centrality는 상수관망의 특정절점에 수질오염 사고가 발생하였을 때 오염원의 이동 가능한 경로의 수에 따라 그 값이 달라지며, 결과값에 의하여 수질오염측정지점이 선정된다. 본 연구에 의한 결과는 상수관망이 복잡하여 시뮬레이션을 통한 분석이 어렵고 많은 시간과 계산능력이 요구 될 경우 대안기법으로 활용될 수 있을 것으로 판단된다.