• Journal of Environmental Impact Assessment
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• v.15 no.1
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• pp.13-22
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• 2006

The Korean government adopted the integrated stream water management policy recently with growing perception that natural disasters and pollution in Korea have been due not only to such human factors as urbanization and industrialization, but also to the policy of functionally separated management of irrigation, flood control and ecological management. Contrary to its good intention, research result shows that it is not realistic to expect that this new integrated policy in Korea will work well. In order to be an effective policy and program evaluation, this paper suggests that evaluation indicator on related programs and projects should be made through bottom-up process. For example, environmental benefit should be taken into account rather than just economic benefit, and cultural and social characteristics in the project region should be also considered seriously.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.100-110
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• 2020

Recently, the frequency of typhoon and torrential rain due to climate change is increasing. In addition, the upsurge in the complexity of urban sewer network and impervious surfaces area aggravates the inland flooding damage. In response to these worsening situations, the central and local governments are conducting R&D tasks related to predict and mitigate the flood risk. Researches on the analysis of inundation in urban areas have been implemented through various ways, and the common features were to evaluate the accuracy and justification of the model by comparing the model results with the actual inundation data. However, the evaluation procesure using available urban flooding data are not consistent, and if there are no quantitative urban inundation data, verification has to be performed by using press releases, public complaints, or photos of inundation occurring through 'CCTV'. Because theses materials are not quantitative, there is a problem of low reliability. Therefore, this study intends to develop a comparative analysis procedure on the quantitative degree and applicability of the verifiable inundation data, and a systematic framework for the performance assessment of urban flood analysis model was proposed. This would contribute to the standardization of the evaluation and verification procedure for urban flooding modelling.

• Journal of Korean Society of Rural Planning
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• v.17 no.2
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• pp.23-32
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• 2011

The purpose of this study is to produce basic planning criteria required in ecological restoration and improvement works of streams in rural area through the application of stream assessment methods (water quality, soil environment, and ecological function assessment) at 6 study sites of Han River basin. The investigation results were as followings; 1) There were the evaluation items like a manure use, salt degree, river peripheral tree, which did not fitted to apply to domestic streams, in the SVAP (Stream Visual Assessment Protocol) and NRCS Riparian Assessment that were evaluation models developed in USDA. The area inhabitants with a little knowledge and education personally seems to utilize the evaluation methods through improvement partly with an aspect that evaluation is slightly easy. 2) From the stream assessment results, the construction of diverse pools, large woody debris and isolated backwater pool are needed to improve a few of problems observed at the mostly study sites. The result of NRCS Riparian Assessment showed that the improvement of stream bank vegetative communities is needed by planting tree with deep-binding root masses, and managing of noxious weeds and exotic undesirable plants. 3) Summing up, the assessment results showed that the assessment scores were higher at upstream than downstream, the stream with totally maintenance than that with partly maintenance, the stream with slope bank than that with vertical bank, and the stream with a flood plain than that without a flood plain. So, the direction of stream maintenance projects must be set by consideration of those results.

• Structural Engineering and Mechanics
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• v.28 no.1
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• pp.1-18
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• 2008

The conventional design of bridge piers against scour uses scour equations which involve number of uncertain flow, sediments and structural parameters. The inherent high uncertainties in these parameters suggest that the reliability of piers must be assessed to ensure desirable safety of bridges against scour. In the present study, a procedure for the reliability assessment of bridge piers, installed in main and flood channels, against scour has been presented. To study the influence of various random variables on piers' reliability sensitivity analysis has been carried out. To incorporate the reliability in the evaluation of safety factor, a simplified relationship between safety factor and reliability index has been proposed. Effects of clear water (flood channel) and live bed scour (main channel) are highlighted on pier reliability. In addition to these, an attempt has also been made to explain the failure of Black mount bridge of New Zealand based on its pier's reliability analysis. Some parametric studies have also been included to obtain the results of practical interest.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.1-21
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• 2003

I introduce the Flexible Dam Operation (FDO) and some of sediment control techniques In dams which are implemented as trials to avoid or reduce environmental impact of dams on the downstream reaches. The FDO is a dam management method to improve river environment in the downstream reaches by means of the flushing flow, the maintenance flow and so on utilizing a vacant portion of capacity for flood control without interrupting prime flood control function during the rainy/typhoon season. It Is suggested by the guideline of the FDO that EDO should be implemented regularly after the trial for about three years. The basic conception of the FDO is described here. The example of excavation of deposited sediments in check dams and placement of sand ana gravel immediately downstream of the dams and the example of coordinated sediment flushing are described as some of sediment control techniques in dams. Now they are at the stage of experiment and trial. Therefore, it is important to increase examples and establish the technical methodology and the environmental evaluation method for them.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.691-698
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• 1997

The risk assessment model for dam and levee is applied to a river where two adjacent dams are located in the upstream of the watershed. "A" dam is proven to be safe with 200-year precipitation and unsafe with PMP condition, whereas "B" dam to be safe with 200-year precipitation and PMP condition. The computed risk considering the uncertainties of the runoff coefficient. initial water depth and relevant data of the dam and spillway turn out to be equivalent results in Monte-Carlo and AFOSM method. In levee risk model, this study addresses the uncertainty of water surface elevation by Manning's equation. Monte-Carlo simulation with the variations of Manning's roughness coefficient is calculated by assuming that it follows atriangular distribution. The model can be used for preparing flood risk maps, flood warning systems, and establishing nation's flood disaster protection plan.

• The Journal of the Korea Contents Association
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• v.9 no.10
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• pp.417-426
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• 2009

The eco-friendly river restoration issue has been increased and the importance of the vegetation along the river banks has been understood with its scenery and significant role. However vegetation reduces the stream flow cross section and brings negative effects such as increase of water flow resistance and decreases of river flow velocity. In this study, the method to choose roughness coefficient is studied in the sudden changed hydraulic characteristics by river restoration. Using the HEC-RAS model and the two-dimensional vertical analysis method, Yangjae stream was calculated that the roughness coefficient of the main channel is 0.011~0.159 after river restoration, 0.031 without vegetation on the flood plain, and 0.034~0.506 with vegetation on the flood plain. The level of water in the river is predicted to rise 0.13~0.34m at 30% of vegetation density increase.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.383-392
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• 2014

The purpose of this study is to simulate inundation and evaluate the applicability of LISFLOOD model to the streams in South Korea by comparing with the inundation map using FLUMEN. The suggested levee breaching scenarios were applied to the LISFLOOD model, and the results obtained from scenarios were evaluated. The modeling results using LISFLOOD by appling the levee breaching scenarios showed 0.2% ~ 42% relative error with FLUMEN model in inundation area. But the relative error of maximum inundation area by overlapping all the flood analysis results from levee breaching scenarios such as the way making flood risk map was approximately 1.2% between two models. Meanwhile, LISFLOOD model was easy to construct input data, DEM as topographic data and discharge hydrograph as upper boundary conditions. And computing time of LISFLOOD was shorter than FLUMEN. Therefore LISFLOOD model can be applied usefully in the region that needs immediate inundation modeling.

• Journal of the Society of Disaster Information
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• v.11 no.3
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• pp.346-355
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• 2015

The study is to understand the needs of flood victims of Korea through the analysis of relief goods, and to assess extent of support-service efficiencies. According to the analysis, both emergency relief kit and cooking relief kit are possibly labelled 'the primary' and 'the secondary necessaries' respectively. Here the former includes those items directly related with basic living condition for the victims while the latter does some of items for more convenience lifestyle. The results of the study would be substantial in the sense that they could provide some useful clues upon which improvement policies or programs associated with relief goods for flood victims are derived.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.433-446
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• 2021

In this study, the future flood inundation changes under a climate change were simulated in the Tonle Sap basin in Cambodia, one of the countries with high vulnerability to climate change. For the flood inundation simulation using the rainfall-runoff-inundation (RRI) model, globally available geological data (digital elevation model [DEM]; hydrological data and maps based on Shuttle elevation derivatives [HydroSHED]; land cover: Global land cover facility-moderate resolution imaging spectroradiometer [GLCF-MODIS]), rainfall data (Asian precipitation-highly-resolved observational data integration towards evaluation [APHRODITE]), climate change scenario (HadGEM3-RA), and observational water level (Kratie, Koh Khel, Neak Luong st.) were constructed. The future runoff from the Kratie station, the upper boundary condition of the RRI model, was constructed to be predicted using the long short-term memory (LSTM) model. Based on the results predicted by the LSTM model, a total of 4 cases were selected (representative concentration pathway [RCP] 4.5: 2035, 2075; RCP 8.5: 2051, 2072) with the largest annual average runoff by period and scenario. The results of the analysis of the future flood inundation in the Tonle Sap basin were compared with the results of previous studies. Unlike in the past, when the change in the depth of inundation changed to a range of about 1 to 10 meters during the 1997 - 2005 period, it occurred in a range of about 5 to 9 meters during the future period. The results show that in the future RCP 4.5 and 8.5 scenarios, the variability of discharge is reduced compared to the past and that climate change could change the runoff patterns of the Tonle Sap basin.