• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.155-165
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• 2010

In low-lying districts of urban areas, pump stations were built to protect flooding by the heavy rain. Particularly, the automatic pump operation system was installed for efficiency in the pump stations of Seoul. However, the effective pump operation is difficult under existing operating system because the system only performs operation by reservoir depth. This study would like to improve the real time operating system suggested by Jun et al.(2007) and to apply the system Gasan 1 pump station in Seoul. For various design rainfall events, maximum water levels simulated by the suggested system were 10~70cm lower than results by the existing system. And overflow volume at upstream manholes were 50% reduced. We converted the flood control effects by establishment of the suggested system to economic indicators. To obtain the same effect, approximately 4.9 billion won needs to expand pump capacities or 3.2~6.9 hundreds million won needs to construct storm water detention on upstream area. The suggested system could improve the flood control stability by efficient operation of the existing pump station.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.303-312
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• 2020

An underground deep tunnel system is a facility in form of a reverse siphon for an under flood defense structure. In this study, the 'Shinwol rainwater storage and drainage system', which is under construction for the first time in South Korea, in order to confirm the effects of undular bore and pressurized air on the hydraulic stability of the facility in various flood scenarios a hydraulic model experiment was performed. As a result of this study, it was analyzed that the undular bore generated downstream pushed the pressurized air collected in the facility while moving upstream, and the pressure inside the pipe increased at this time. It was analyzed that the pressure during the passage of the undular bore was greater than the sum of the static pressure and dynamic pressure at the time and overflow occurred when the cross-sectional size of the pressurized air was more than 40% of the cross sectional area of the tunnel. It is determined that this is correlated with the volume of pressurized air collected in the facility, and it is determined that it is necessary to study the relationship between velocity of undular bore and the volume of pressurized air in the future.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.213-220
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• 2014

Recently, river maintenance is change due to concern for the environment increases. Thus, the river restoration and river environment is best part of river maintenance. In case of Korea, existing river is improvement straightly for flood control and transportation. When the stream channel is straightly, maintain stability is important. Thus, construction of levees along the river. The various river structures for the purpose of flood control and transportation are inhibit factors of longitudinal and lateral connectivity. Connectivity is defined as the maintenance of lateral, longitudinal, and vertical pathways for biological, hydrological, and physical processes. Long-term point of view, increased connectivity is very important for a healthy ecosystem composition. As the first step of river restoration, this study described theory and concept of river continuum and the numerical model was applied to a real topography to simulate the flow analysis with or without segregated and blocked space in the Mankyung river. The results of this study can be utilized to develop the watershed connectivity assessments methods in order to the river restoration.

• Journal of Korea Water Resources Association
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• v.52 no.4
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• pp.301-312
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• 2019

The importance of the dual drainage system model has increased as the urban flood damage has increased due to the increase of local storm due to climate change. The dual drainage model is a model for more accurately expressing the phenomena of surface flow and conduit flow. Surface runoff and pipe runoff are analyzed through the respective equations and parameters. And the results are expressed visually in various ways. Therefore, inundation analysis results of dual drainage model are used as important data for urban flood prevention plan. In this study, the applicability of the COBRA model, which can be interpreted by combining the dual drainage system with the natural watershed and the urban watershed, was investigated. And the results were compared with other dual drainage models (XP-SWMM, UFAM) to determine suitability of the results. For the same watershed, the XP-SWMM simulates the flooding characteristics of 3 types of dual drainage system model and the internal flooding characteristics due to the lack of capacity of the conduit. UFAM showed the lowest inundation analysis results compared with the other models according to characteristics of consideration of street inlet. COBRA showed the general result that the flooded area and the maximum flooding depth are proportional to the increase in rainfall. It is considered that the COBRA model is good in terms of the stability of the model considering the characteristics of the model to simulate the effective rainfall according to the soil conditions and the realistic appearance of the flooding due to the surface reservoir.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.575-586
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• 2023

River vegetation has important functions such as providing a habitat for the river ecosystem and physical stability of the river bank. It also has adverse effects such as aggravating flood damages due to the increase in roughness coefficient and drag forces. River vegetation management is very important in finding a balance between flood and ecological management. There are still many uncertainties about the effect of vegetation on rivers. In this study, in order to analyze the effect of vegetated flow, the flow patterns according to the vegetation roughness are analyzed through a two-dimensional unsteady flow model for Chopyeong island of the Imjin River. According to the results of the 2D flow analysis using the HEC-RAS 2D model, the velocity distribution in the bend of the Imjin River was greatly affected by the vegetation roughness of Chopyeong Island. The formation of the main flow outside the bend of Chopyeong Island during flooding is presumed due to the influence of tree and grass on Chopyeong Island. If tree are distributed throughout Chopyeong Island, the velocity outside the bend is expected to be higher. River vegetation causes the effect of raising the water level, and could cause a change in the velocity distribution.

• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.41-47
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• 1999

More than 100 bridges in Korea have been annually collapsed or badly damaged by the scouring around bridge piers, particularly in the flood season. To prevent from such a tragedy, the fundamental study on the bridge scouring is required, which is essential not only to estimate the scour depth with reliability but to take it into consideration in its design. However, it is not easy to find out the physical scour mechanism since many factors on the scour are coupled with. Moreover, there exists none of the measured data sufficiently for the primary research on the bridge scour depths. In this study the field measurements are carried out to provide the fundamental data for the research and the design. Scouring depth, pier width, flow depth, and the approaching velocity and degree of pier nose are measured broadly in small and medium streams. From these measurements the present situation on bridge scours can be understood and some of important factors to affect the stability of bridges are analyzed.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.213-217
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• 1999

The river bank is one of the most important structure of fluvial hydraulic structure. Because the breaking of river bank is the cause of calamity, the durability and stability of river bank an very important factors. The breaking of river bank is the cause of the overflow of flood and the leakage of river bank. In this study, we investigated the leakage of river bank using the resistivity probing and estimated the volume of leakage using the weighted residual method The study basin of this study is the upstream of Sumji river basin and the factor of river bank is length 300 m and berm 2.0 m and width 4.5 m and height 4 m. We evaluated the leakage of river basin using using the resistivity probing and estimated the leakage volume using the weighted residual method. The result of this study, the leakage of river bank generated at the point of 39~45 m 80~90 m. 218~222 m. 214~250 m and the type of leakage is the rectangle and the polygon. And the leakage volume of this points evaluated 2.7$\times$$10^{-3}$ $\textrm{m}^3$/sec.

• Journal of Korean Medical classics
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• v.21 no.4
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• pp.75-83
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• 2008

Based on the sentence "The number of my family member and relatives reached around 200, but since the first year of Geonan(建安) era, two thirds of them died and seven out of ten died of cold damage in less than ten years" in Sanghanjapbyeongron(Treatise on Cold Damage and Miscellaneous Diseases), which is allegedly known to be written by Jangnunggyeong(張仲景), we analyzed the sentence by three factors of time, location and people. These factors are used in the investigation of the disease outbreak, and through this analysis, following conclusions were made. 1. Approximate 10 year crude mortality rate since A.D 196(the first yea of Geonan era) in Jangsa(長沙) province was 67 out of 100 in the population. Approximate 10 year disease-specific mortality rate of cold damage since A.D 196(the first yea of Geonan era) in Jangsa(長沙) province was 47 out of 100 in the population. Regardless of age, gender or other demographic variables, approximate 10 year proportionate mortality ratio since A.D 196(the first yea of Geonan era) in Jangsa province was 70.2%, which lead to the assumption that 70% of death is cold-damage related. 2. Increased disease-specific mortality rate by cold damage in Jangsa(長沙) province for about 10 years since A.D 196(the first yea of Geonan era), and followed increased crude mortality rate in the population, threatened the stability of nation or local government. This is due to the repeated war in late Han Dynasty with political chaos and repeated flood caused by geographical disadvantage in Jangsa province.

• Water for future
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• v.29 no.6
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• pp.167-178
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• 1996

The simulation techniques of hydrologic data series have been developed for the purposes of the design of water resources system, the optimization of reservoir operation, and the design of flood control of reservoir, etx. While the stochastic models are usually used in most analysis of water resources fields for the generation of data sequences, the indexed sequential modeling (ISM) method based on generation of a series of overlapping short-term flow sequences directly from the historical record has been used for the data generation in western USA since the early of 1980's. It was reported that the reliable results by ISM were obtained in practical applications. In this study, we generate annual inflow series at a location of Hong Cheon Dam site by using ISM method and first order autoregressive model (AR(1)), and estimate the drought characteristics for the comparison aim between ISM and AR(1).

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.139-145
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• 2010

Recently, close-to-nature stream improvement works have been carried out in urban streams, where eco-friendly bank revetment methods have been adopted. These bank revetment methods are vulnerable to be damaged or washed away by floods compared to the traditional methods which use concrete materials. Damage analysis methods on the urban streams by the floods of severe rain storm are presented. The analysis methods are the graph-using method and the grid method, which are derived from the survey results at Gwangju stream. Damage analysis grid which is intersected velocity grid and material strength grid is the highest correlation with the damage survey grid. The biggest damage on the bank revetments have been occurred around the crossing structures. Big damages have also been occurred in the connection of low water revetment and the terrace land, and around the structures in the terrace land of the stream.