• Journal of Korean Society of Disaster and Security
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• v.15 no.2
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• pp.37-44
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• 2022

As the frequency of torrential rains and typhoons increases due to climate change, the frequency of occurrence of debris flow is also increasing. In particular, in the case of Kangwon-do, the occurrence of damage caused by mountain disasters is increasing as it has a topographical characteristic where the mountains and the coast are in contact. In order to analyze the flow characteristics in the sedimentary part of the debris flow, input data were constructed through numerical maps and field data, and a two-dimensional model, FLO-2D, was simulated. The damaged area was divided into the inflow part of the debris flow, the village center, and the vicinity of the port, and the flow center and flow velocity of the debris flow were simulated and compared with field survey data. As a result, the maximum flow depth was found to be 2.4 m at the debris flow inlet, 2.7 m at the center of the village, and 1.4 m at the port adjacent to the port so the results were similar when compared to the field survey. And in the case of the maximum flow velocity, it was calculated as 3.6 m/s at the debris flow inlet, 4.9 m/s in the center of the village and 1.2 m/s in the vicinity of the port, so It was confirmed that the maximum flow center occurred in the section where the maximum flow rate appeared.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.915-926
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• 2016

The purpose of this study is to classify debris flow hazard zones in urbanized areas using multivariate statistical analyses and to suggest customized management strategies to each areal type. Using field survey data set in Seoul, 49 sample debris hazard zones are selected. Clustering and discriminant analyses show that debris flow hazard zones are classified into two types. Surrounding land use and land slope are major factors influencing to the categorization. The results suggest that, by considering the characteristics of each areal type, more customized management strategies for debris flow hazard are necessary. Particularly, in addition to traditional structural measures, non-structural measures including land use and development control for downstream built-up areas should be emphasized in urbanized areas to mitigate human and property damages from debris flow hazard more fundamentally.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.57-65
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• 2019

In this study, to investigate the effect of cylindrical countermeasure on the flow characteristics of debris flow, a series of small-scale tests were conducted using a flume with cylindrical baffles. Various heights and row numbers of installed baffles were considered as a test condition. High speed cameras and laser level sensors were also installed at the top and side of the channel, respectively, to capture the debris flow dynamics before and after baffles. Based on test results, the energy dissipation of debris flow due to baffles was analyzed. Test results showed that baffles can significantly reduce the velocity and flow depth of debris flows. The energy dissipation effect of baffles also increase as the increase of height and row number of baffles.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1252-1254
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• 2003

Debris flows associated with landslides occur as one of the most devastating natural disasters that threat Taiwan. Typically, three essential factors are needed simultaneously to trigger debris flow, namely sufficient soils and rocks, favorable slope, and abundant water. Among the three essentials, the slope is natural and static without external forcing, while the landslide is generally induced by earthquake or rainfall events, and the water is produced by heavy rainfall events. In this study, we analyzed the landslides triggered by the typhoons Herb (1996) and typhoon Troaji (2001). It is concluded that the statistical data are useful to quantify the threshold of the potential landslide area. Then, the possibility to prevent the debris flow occurrence may be increased.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.5
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• pp.809-815
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• 2020

A number of investigations and studies have been conducted in various fields regarding the sediment disasters of Mt. Woomyeon that occurred in July 2011. We collected and compared the topographic information of the general points where debris flows did not occur and the collapse points where the debris flow occurred in order to find out the characteristics of the collapse points in Woomyeon mountain. The collected topographic information is altitude, curvature, slope, aspect and TPI(topographic position index). As a result of comparison, there were relatively many collapse points at an altitude of 210m to 250m, and at a slope of 30° to 40°. In addition, the risk of collapse was low in a cell where the curvature was close to 0, and the risk was higher in concave terrain than in convex terrain. In the case of TPI, there was no statistical difference between the general points and the collapse points when the analysis radius was larger than 200m, and there was a correlation with the curvature when the analysis radius was smaller than 50m. In the case of debris flows that are affected by artificial structures or facilities, there is a possibility of disturbing the topographic analysis results. Therefore, if a research on debris flow is conducted on a mountain area that is heavily exposed to human activities, such as Woomyeon mountain, diversified factors must be considered to account for this impact.

• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.213-220
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• 2015

This study was carried out to determine the distribution of factors as effected by debris flow in Ulsan and Pusan metropolitan areas because mainly debris flow caused by typhoons and local heavy rainfall events is mainly attributed to damage of human being ad property. The high risk degree of debris flow was to affected by east (20%), northeast (20%) and northwest (20%) slopes with stand age class with elevation (69%) of 100-200 (33%). Also, the risk was high in high erosion collapse degree with slope degree of $20-25^{\circ}$ with over 300 mm (100%) of maximum daily rainfall events and 50-100 mm (50%) or >100 mm (50%) of maximum hourly rainfall events with <5 km of stream path and <50 ha of catchment area. Landslide debris and wood residue flow was also related to igneous rocks (73%) and bank collapse types of debrs flow (57%).

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4003-4013
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• 2021

During the long-term cooling (LTC) phase of a loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR), water is supplied from the containment sump to the reactor coolant system (RCS) by the flooded sump water to the Reactor Vessel (RV) through the broken pipes. As part of the technical efforts for resolving GSI-191 [( Reid and Crytzer, May. 2007) 1, consideration is needed for the consequences of debris penetrating the sump screen and propagating downstream into the RV. Injection of debris (fiberglass) into the RV during the LTC recirculation phase needs special attention to assure that reactor core cooling is maintained. The point of concern is the potential for debris to adversely affect the reactor core flow paths or heat transfer [2]. However, all the experiments for proving the coolability of RV have been done with the assumption of the most of debris would be transferred to the RV and the bottom nozzle of the FAs. The purpose of the tests is to quantify the amount of the debris that would be accumulated at the lower plenum and the debris that passes through the FAs since non-conservatism of other researches assumptions that have been used in the past experimental or analytical programs.

• Journal of Korean Society of Disaster and Security
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• v.12 no.3
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• pp.1-11
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• 2019

This study selected the national park area of Mt. Seorak in Inje-gun, Gangwon-do, where a lot of debris flow occurred due to the heavy rainfall and conducted a field survey. In addition, topographic spatial data were constructed using the GIS technique to analyze watershed characteristics. For the construction of terrain data after the disaster, the debris flow occurrence section was scanned and the 3D topographic data was constructed using the terrestrial LiDAR. LiDAR terrain data are compared to digital maps(before disaster) to assess precision and topographic data before and after the disaster were compared and analyzed. Debris flow diffusion area was calculated using FLO-2D model and compared debris flow occurred section.

• Journal of the Korean GEO-environmental Society
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• v.20 no.10
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• pp.15-27
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• 2019

In this study, in order to analyze the effect of cylindrical baffles on the debris flow energy, small-scale tests were conducted using a flume with cylindrical baffles. Various row numbers of installed baffles were considered as a test condition. To investigate the scale effect of debris flow and cylindrical baffles on flow characteristics, large-scale tests were also performed according to varying row numbers of baffle for same baffle configuration with small-scale tests. Both small- and large-scale test results showed that the increase of row number of baffle increase the energy dissipation effect due to reduction of the velocity and flow depth of debris flow.

• 기술발표회
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• s.2006
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• pp.146-155
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• 2006

A study for damage degree and reduction programs of disaster was performed after collecting and analyzing the damage data by the type of flood damage resulting from the localized rainfall Gangwon area has been damaged by heavy localized rainfall between July 15 and 17 in 2006 Specially, a number of people was killed and much properties were lost in Inje, Yangyang and Pyeongchang area Recently, the damages by debris flow has been increased more than any other disaster causes, because heavy rainfall closed to about 100mm/hr by global warming in short time has been developed frequently. In other words, an area forming a highland has a potential debris flow Therefore, in this study, the damages data by debris flow in the area of Inje and Yangyang were collected and analyzed to consider the type of flood damage In future, it must be tried to find a complementary solution and establishing management system for debris flow when the civil construction begins