• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.332-332
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• 2021

도시화가 상당히 이뤄지고 기습적인 폭우의 발생이 불확실하게 나타나는 시점에서 재산 및 인명피해를 야기할 수 있는 내수침수에 대한 위험도가 증가하고 있다. 내수침수에 대한 예측을 위하여 실측강우 또는 확률강우량 시나리오를 참조하고 연구대상 지역에 대한 1차원 그리고 2차원 수리학적 해석을 실시하는 연구가 오랫동안 진행되어 왔으나, 수치해석 모형의 경우 다양한 수문-지형학적 자료 및 계측 자료를 요구하고 집약적인 계산과정을 통한 단기간 예측에 어려움이 있음이 언급되어 왔다. 본 연구에서는 위와 같은 문제점을 해결하기 위하여 단일 도시 배수분구를 대상으로 관측 강우 자료, 1, 2차원 수치해석 모형, 기계학습 및 딥러닝 기법을 적용한 실시간 홍수위험지도 예측 모형을 개발하였다. 강우자료에 대하여 실시간으로 홍수량을 예측할 수 있도록 LSTM(Long-Short Term Memory) 기법을 적용하였으며, 전국단위 강우에 대한 다양한 1차원 도시유출해석 결과를 학습시킴으로써 예측을 수행하였다. 침수심의 공간적 분포의 경우 로지스틱 회귀를 이용하여, 기준 침수심에 대한 예측을 각각 수행하였다. 홍수위험 등급의 경우 침수심, 유속 그리고 잔해인자를 고려한 홍수위험등급 공식을 적용하여 산정하였으며, 이 결과를 랜덤포레스트(Random Forest)에 학습함으로써 실시간 예측을 수행할 수 있도록 개발하였다. 침수범위 및 홍수위험등급에 대한 예측은 격자 단위로 이뤄졌으며, 검증 자료의 부족으로 침수 흔적도를 통하여 검증된 2차원 침수해석 결과와 비교함으로써 예측력을 평가하였다. 본 기법은 특정 관측강우 또는 예측강우 자료가 입력되었을 때에, 도시 유역 단위로 접근이 불가하여 통제해야 할 구간을 실시간으로 예측하여 관리할 수 있을 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.744-748
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• 2008

우리의 삶의 터전이 도시화됨에 따라 수문현상에도 많은 변화가 생겼다. 이로 인해 기존의 수문해석을 위한 방법을 대신해 도시화된 유역의 새로운 수문해석 방법의 개발이 불가피하게 되었다. 이에 따라 본 연구에서는 도시유출 모형인 SWMM의 대표적 프로그램인 XP-SWMM을 이용하여 도시유역의 유출모의를 하였다. 대상유역으로 선정한 곳은가양천배수분구로 전형적인 도시 하천 유역모습을 하고 있다. 이 유역의 특성치와 확률강우량 산정 후 XP-SWMM 모형에 적용시켜 재현기간별 첨두홍수량을 구하고, 동일 유역을 HEC-HMS로 모의하여 그 차이를 분석하였다. 도시화가 진행되면서 대규모 시설 등이 들어서면서 도로와 인도가 포장되므로 침투는 감소하고, 따라서 유역내 조도계수가 감소되며, 수로망 정비 등에 의해 유입시간이 빨라져 첨두홍수량이 증가하게 되었다. 이와 같은 변화로 인해 기존 홍수량을 구하기 위한 방법의 변화는 필수 불가결하게 되었다. 따라서 본 연구의 중점과제인 저류지에 의한 홍수조절능력에 대한 분석은 대상 유역내에 일정한 크기의 저류지를 상 중 하류위치에 따라 지점선정 후 그에 따른 홍수량과 침수량의 변화를 비교..분석하여 저류지 위치별 홍수조절능력에 대한 평가를 실시하였다.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.730-738
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• 2013

In recent years, low impact development (LID) has emerged as an effective approach to control stormwater in an urban area, and watershed and stormwater managers need modeling tools to evaluate alternative plans for controlling stormwater. This study illustrates how to design and evaluate the effect of non-point pollutant management using SUSTAIN which is developed by USEPA. SUSTAIN can provide evaluating, selecting, and placing LID facilities in an urban catchment based on user-defined cost-effectiveness criteria. Also, this paper suggests a minimal methodology for estimating model parameters for modeling an ungauged urban catchment to reflect the situation of typical Korean urban interested catchments which are usually ungauged. In addition, the optimal length of various LID facilities and the optimal number of units in our test catchment are estimated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.395-406
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• 2018

The XP-SWMM model, widely used for inundation analysis of urban watersheds, underestimated the inundation area (range) because the manhole was regarded as a node and the influence of the local loss occurring in the surcharged manhole can not be considered. Therefore, it is necessary to analyze the applicability of the head loss coefficients considering the local loss in the surcharged manholes in inundation analysis using XP-SWMM. The Dorim 1 drainage section of the Dorim-river watershed, where frequent domestic flood damage occurred, was selected as the study watershed. The head loss coefficients of the surcharged manholes estimated from the previous experimental studies were applied to the inundation analysis, and the changes of the inundation area with and without the application of the head loss coefficients with manhole types were compared and analyzed. As a result of inundation simulation with the application of head loss coefficients, the matching rates were increased by 17% in comparison with the without application of them. In addition, the simulated inundation area applied only the head loss coefficients of straight path manholes and applied up to the head loss coefficients of combining manholes ($90^{\circ}$ bend, 3-way, and 4-way) were similar. Therefore, in order to accurately simulate the storm drain system in urban areas, it could be to carry out two-dimensional inundation analysis considering the head loss coefficients at the surcharged manholes. It was expected that the study results will be utilized as basic data for establishing the identification of the inundation risk area.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.397-405
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• 2017

In case of inundation in a city where populations and properties are highly concentrated, unlike rural areas it is necessary to apply the method of calculating the damage amount considering the sewage overflow and the corresponding building damage. In this study, Dorim 1 drainage sector has been analyzed with Multi-Dimensional Flood Damage Assessment (MD-FDA) for flood forecast. It is analyzed with past flood history through the SWMM model and calculated the amount of damage with district base data and the result of flow analysis. The result of the SWMM model to predict a range of flood, it was shown that the wide area after 4 hours (at 16:30) by sewer overflow. The building damage was estimated using MD-FDA. As a result, the maximum flood area has shown as $205,955m^2$ (0~0.5 m: $205,190m^2$, over 0.5 m: $865m^2$) and estimated building damage of Dorim 1 drainage sector is approximately 15.5 billion KRW (Korean won) and other contents is 7 billion KRW (Korean won). Also from 0 to 0.5 m depth estimated damage is approximately 22.4 billion KRW (Korean won) and over 0.5 m is 100 million KRW (Korean won). Based on the results of this study, it would be necessary to estimate the amount of sub-divided flood damage in urban areas according to various damage patterns such as flood depth and flood time.

• Journal of Korea Water Resources Association
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• v.48 no.9
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• pp.729-741
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• 2015

This study examined the applicability of MBLRP (Modified Bartlett-Lewis Rectangular Pulse) rainfall generation model for an urban flood simulation which is a type of Poisson cluster rainfall generation model. This study constructed XP-SWMM model for Namgajwa area of Hongjecheon basin, which is a two-dimensional pipe network-surface flood simulation program and computed a flood discharge and a flooded area with input data of synthetic rainfall time series of 200 years that were generated by the MBLRP model. This study compared the data of flood with synthetic rainfall and flood with corresponding values which were based on design rainfall. The results showed that the flooded area computed with MBLRP model was somewhat smaller than the corresponding values on the basis of the design. A degree of underestimation was from 8% (5 year) to 34% (200 year) and the degree of underestimation increased as a return period increased. This study is meaningful in that it proposes methodology that enables quantifiability of uncertain variables which are related to a flooding through Monte Carlo analysis of urban flooding simulation and applicability and limitations thereof.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.957-964
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• 2013

This research is on the methodology of flood risk assessment using flooding characteristic values. Necessity of design magnitude for flood control considering floods was judged by plotting peak flow with respect to frequency and duration, and flooding magnitude was defined with 6 flooding characteristic values which were proposed to be significant factors when assessing flooding magnitude. Precipitation data used in the assessment modeling were applied by combining all the possible precipitation events. After overlapping the simulated results with precipitation matrix by flooding characteristic values, contour map was drawn, and Flooding characteristic contour graph for possible rainfall events were suggested in respect of all possible precipitation. Flooding characteristic contour graph for possible rainfall events was confirmed that reducing of damage magnitude of each flood characteristic value was figured out easily. The flood risk assessment methods suggested in this study would be a good reference for urban drainage system design, which only focuses on pipe conduit.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.201-201
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• 2017

서울시 효자배수분구(광화문 지역)는 2010년, 2011년 호우로 인해 침수 피해가 많이 발생했던 지역으로 당시 주요 침수피해 원인은 광화문 사거리 및 경복궁역 인근에 위치하고 있는 굴곡 관로의 손실수두 증가(유입, 만곡, 마찰손실 등), 지하매설물로 인한 통수단면 감소 등으로 조사되었다. 따라서 대상지역의 침수 원인을 정확히 분석하기 위해서는 관거의 만곡, 급 확대 및 급 축소에 따른 손실계수의 적용이 요구된다. 손실계수는 유입부, 만곡부에 대한 계산식을 이용하여 산정하고 모형에 적용하였으며 적정 손실계수 값을 얻기 위해 손실계수에 대한 민감도 분석을 수행하였다. 모의 검토 대상기간은 우수관거내 수심 측정자료가 존재하는 4개의 이벤트를 선정하였으며 같은기간에 해당하는 AWS 매분단위 강우자료를 취득하여 모의에 적용하였다. 또한, 적정 손실계수를 선정하기 위해 관측치와 모의치의 적합도를 평가하였으며, 평가지표는 자료 개수에 관계없이 절대적으로 평가할 수 있는 NSE(Nash-Sutcliffe Efficiency)를 사용하였다. 손실계수 적용 여부에 따른 분석결과 손실계수를 적용한 모의치가 관측치의 오차가 미적용한 모의치보다 적합도의 평가지표가 우수하게 분석되었다. 손실계수 민감도 분석 결과는 경험식에 의해 산정된 손실계수를 적용한 Case3의 NSE가 가장 우수하게 분석되었다. 이와같이 도시 지역의 침수분석에 있어 우수관거에 대한 손실계수 적용으로 분석모형의 정밀도를 높일 수 있는 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.49 no.6
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• pp.519-528
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• 2016

Frequently torrential rain is occurred by climate change and urbanization. Urban is formed with road, residential and underground area. Without detailed topographic flooded analysis consideration can take a result which are wrong flooded depth and flooded area. Especially, flood analysis error of population and assets in dense downtown is causing a big problem for establishments and disaster response of flood measures. It can lead to casualties and property damage. Urban flood analysis is divided into sewer flow analysis and surface inundation analysis. Accuracy is very important point of these analysis. In this study, to confirm the effects of the elevation data precision in the process of flooded analysis were studied using 10m DEM, LiDAR data and 1:1,000 digital map. Study area is Dorim-stream basin in the Darim drainage basin, Sinrim 3 drainage basin, Sinrim 4 drainage basin. Flooding simulation through 2010's heavy rain by using XP-SWMM. Result, from 10m DEM, shows wrong flood depth which is more than 1m. In particular, some of the overflow manhole is not seen occurrence. Accordingly, detailed surface data is very important factor and it should be very careful when using the 10m DEM.

• Journal of Korea Water Resources Association
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• v.44 no.10
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• pp.777-786
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• 2011

In the previous researches for storm sewer design, the flow path, pipe diameter and pipe slope were determined to minimize the construction cost. But in the sewer networks, the flows can be changed according to flow path. The current optimal sewer layout models have been focussed on satisfying the design inflow for sewer designs, whereas the models did not consider the occurrences of urban inundation from excessive rainfall events. However, in this research, the sewer networks are determined considering the superposition effect to reduce the inundation risk by controlling and distributing the inflows in sewer pipes. Then, urban inundation can be reduced for excessive rainfall events. An Optimal Sewer Layout Model (OSLM) was developed to control and distribute the inflows in sewer networks and reduce urban inundation. The OSLM uses GA (Genetic Algorithm) to solve the optimal problem for sewer network design and SWMM (Storm Water Management Model) to hydraulic analysis. This model was applied to Hagye basin with 44 ha. As the applied results, in the optimal sewer network, the peak outflow at outlet was reduced to 7.1% for the design rainfall event with 30 minutes rainfall duration versus that of current sewer network, and the inundation occurrence was reduced to 24.2% for the rainfall event with 20 years frequency and 1 hour duration.