• The Journal of Engineering Geology
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• v.28 no.3
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• pp.489-499
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• 2018

A flume experiments was used to study the characteristics of the surface displacements and volumetric water contents (VWC) during torrential rain. The surface displacement and VWC of the granite weathered soil were measured for rainfall intensity (100, 200 mm/hr) and initial ground condition (VWC 7, 14, 26%). The test processes were also recorded by video cameras. According to the test results, The shallow failure is classified into three types: retrogressive failure, progressive failure and defined failure. In the case of retrogressive failure and progressive failure, relatively large damage could occur due to the feature that soil is deposited to the bottom of the slope. the shallow failure occurred when the VWC reached a certain value regardless of the initial soil condition. It was found that the shallow failure can be predicted through the increase patton of the VWC under the condition of the ground dry condition (VWC 7%) and the natural condition (VWC 14%). For high rainfall intensity, progressive failure predominated, and rainfall intensity above a certain level did not affect wetting front transition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.737-746
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• 2019

Most landslides in the country are shallow failures triggered by intense rainfall. Many researchers have revealed the possibility of predicting shallow failure through the volumetric water content (VWC). This study examined how to determine shallow failure using the gradient characteristics of the volumetric water content. For this, flume experiments were conducted using weathered granite soil. To confirm the saturation state of the surface layer under a rainfall intensity of 30 and 50mm/hr, VWC sensors were installed at depths of 10 and 20 cm on the upper, middle and lower slope. The test results showed that a shallow failure determination using VWC could be applied limitedly according to the slope degree. In addition, the effective cumulative rainfall due to the rainfall infiltration velocity is considered the main factor for the failure time. The failure prediction using the gradient of the VWC depends on the installation location and depth of the sensor. According to the experimental data, the measured value at 20 cm below the slope was most effective. Therefore, an analysis method of VWC and the method of selecting the installation location confirmed through this study can provide important data for presenting the measurement criteria using VWC in the future.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.223-231
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• 2012

Many cut slopes are located near national highways, resulting in large annual damage to infrastructure from the collapse of cut slopes. Therefore, to effectively maintain cut slopes, high-risk slopes should be identified and monitored. In this paper, we evaluate the effectiveness of the management of cut slopes using the risk score calculated from cut-slope inventory data. The inventory survey, as a simple assessment of the characteristics of various slopes, was performed to collect basic data that could be obtained visually in the field for the management of cut slopes. This method is not a precise survey, and it was composed of the general status and characteristics of cut slopes, the inspector's assessment, and inventory data in order to estimate a risk score for each slope. In this paper, we calculated the risk score by investigating the present status of cut slopes adjacent to 10,461 national roads. In order to evaluate the effectiveness of using risk score data, we compared the score for stable slopes with those of failed cut slopes. Failed cut slopes occurred in sections with the highest risk score. The results show that risk score derived from the inventory survey of cut slopes are useful in the management of cut slopes with risk of failure and in monitoring large numbers of cut slopes.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.104-115
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• 2014

A levee is defined as an man-made structure protecting the areas from temporary flooding. This paper suggests a methodology for establishing the levee GIS database using the airborne topographic LiDAR(Light Detection and Ranging) data taken in the Nakdong river basins and the WAMIS(WAter Management Information System) information. First, the National Levee Database(NLD) established by the USACE(United States Army Corps Engineers) and the levee information tables established by the WAMIS are compared and analyzed. For extracting the levee information from the LiDAR data, the DSM(Digital Surface Model) is generated from the LiDAR point clouds by using the interpolation method. Then, the slope map is generated by calculating the maximum rates of elevation difference between each pixel of the DSM and its neighboring pixels. The slope classification method is employed to extract the levee component polygons such as the levee crown polygons and the levee slope polygons from the slope map. Then, the levee information database is established by integrating the attributes extracted from the identified levee crown and slope polygons with the information provided by the WAMIS. Finally, this paper discusses the advantages and limitations of the levee GIS database established by only using the LiDAR data and suggests a future work for improving the quality of the database.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.11-22
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• 2018

The safety of tunnels is quantified by quantitative risk assessment when planning the disaster prevention facilities of railway tunnels, and it is decided whether they are appropriate. The purpose of this study is to estimate the probability of the train stopping in the tunnels at train fire, which has a significant effect on the results of quantitative risk assessment for tunnel fires. For this purpose, a model was developed to calculate the coasting distance of the train considering the coefficient of train running resistance. The probability of stopping in case of train fire in the tunnel is predicted by the Monte Carlo simulation method with the coasting distance and the emergency braking distance as parameters of the tunnel lengths and slopes, train initial driving speeds. The kinetic equations for predicting the coasting distance were analyzed by reflecting the coefficient train running resistance of KTX II. In the case of KTX II trains, the coasting distance is reduced as the slope increases in a tunnel with an upward slope, but it is possible to continue driving without stopping in a slope downward. The probability of the train stopping in the case of train fire in tunnel decreases as the train speed increases and the slope of the tunnel decreases. If human error is not taken into account, the probability that a high-speed train traveling at a speed of 250 km/h or above will stop in a tunnel due to a fire is 0% when the slope of the tunnel is 0.5% or less, and the probability of stopping increases rapidly as the tunnel slope increases and the tunnel length increases.

• Journal of Korean Society of Forest Science
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• v.105 no.2
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• pp.223-230
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• 2016

This study was carried out to investigate the quarrying and restoration characteristics on quarry in Korea. We researched quarrying and restoration status, analyzed the relationship between restoration area and permitted period, permitted area, quarrying volume, pit slope width, height, and berm width from 55 quarry sites. Most of the quarries were located in the following conditions : mixed forest, average altitude of less than 300 m, average mountain slope of $61^{\circ}$<, hillside, granite and landslide hazard class. Major quarrying characteristics were permitted period of 6~10 years, permitted area of less than 10 ha, quarrying volume of less than $1,000,000m^3$, a stone type of aggregate, a quarrying type of terrace, pit slope of $61^{\circ}$< Most quarries were restored by themselves, and the main restoration type was slope greening. Also, area ratio of flatland, pit slope, and berm was 54.9:39.6:5.5. Ccorrelation analysis showed that quarrying area was positively correlate with quarrying volume (${\alpha}=0.01$), permitted area, pit width, and pit height (a=0.05).

• The Journal of Engineering Geology
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• v.27 no.2
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• pp.125-132
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• 2017

Approximately 64 percent of Korean territory is covered with mountains, and there is occurred a continuous mountain disaster such as landslide, debris flow and slope failure around mountain slopes due to heavy rainfall and typhoon in the summer season. Even in such a reality, the development of mountain areas is being carried out through the development and expansion of social infrastructures centered on mountain areas, but systematic management is insufficient. Constructions of a forest road facility for mountain slopes can be a cause of mountain disasters intensively in the summer season due to artificially changing the mountain area. In this unstable mountain environment, efforts to build a disaster-resistant environment are urgently needed. This research is to analyze the stability of mountain slopes according to soil depth (1~5 m) and mountain slope ($20{\sim}60^{\circ}$) considering the characteristics of rainfall infiltration under extreme rainfall conditions. As a result, the stability of the mountain slope was found to be different according to the depth of soils and the saturation area of the soil layer. As well as the stability of the mountain area was found to be lower than that of the natural mountain area. Specially, rainfall infiltration occurs at the upper slope of the forest road. For this reason, the runoff phenomenon of rainfall infiltration water occurs clearly when the depth of soil layer is low.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.285-291
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• 2006

The lysimeter ($1.2m\;with{\times}1.6m\;length$) experiment using $^{15}N$ tracer method was conducted to investigate the influence of slopes (degree 5, 15 and 30%) and fertilizer application methods (solid application and fertigation) on the behavior of applied urea in saprolite piled highland with Chinese cabbage cultivation. NDFFs(nitrogen derived from fertilizer) in soil were increased with decreasing of degree of slope and of depth of soil. The recovery as percentage of fertilizer nitrogen by Chinese cabbage were 69.5% for solid application and 76.5% for fertigation in 5% slope, 65.0% for solid application and 70.2% for fertigation in 15% slope, and 56.1% for solid application and 62.3% for fertigation in 30% slope. There, fertigation will make great contributions to the reduction of environmental contamination by run off and to the increase of fertilizer efficiency in Chinese cabbage cultivated highland.

• Journal of Environmental Science International
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• v.29 no.8
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• pp.847-855
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• 2020

This study presented problems and improvements in the quality control of an air monitoring network, using Gyeongnam as an example. 1) The effective utilization rate of the air monitoring was 95%, which showed good management, but the maximum of 2% was indicated by zero or detection limit among measurement data. 2) In the equivalence evaluation of PM_2.5, the slope and intercept satisfy the evaluation criteria; however, 1% of the PM_2.5/PM₁₀ ratios were outliers. 3) All air monitoring stations meet the quality control standards; however, the management status is added to the quality inspection, management system is unified and the related budget is expanded, and systematic commission management is required.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.147-155
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• 2008

Because of increased nonpoint source runoff potential at highland agricultural fields of Kangwon province, effective agricultural management practices are required to reduce the inflow of sediment and other nonpoint source pollutants into the water bodies. The watershed-scale model, Soil and Water Assessment Tool (SWAT), model has been used worldwide for developing effective watershed management. However, the SWAT model simulated sediment values are significantly affected by the number of subwatershed delineated. This result indicates that the SWAT estimated watershed characteristics from the watershed delineation process affects the soil erosion and sediment behaviors. However, most SWAT users do not spend time and efforts to analyze variations in sediment estimation due to watershed delineation with various threshold value although topography falsification affecting soil erosion process can be caused with watershed delineation processes. The SWAT model estimates the field slope length of Hydrologic Response Unit (HRU) based on average slope of subwatershed within the watershed. Thus the SWAT ArcView GIS Patch, developed by using the regression relationship between average watershed slope and field slope length, was utilized in this study to compare the simulated sediment from various watershed delineation scenarios. Four watershed delineation scenarios were made with various threshold values (700 ha, 300 ha, 100 ha, and 75 ha) and the SWAT estimated flow and sediment values were compared with and without applying the SWAT ArcView GIS Patch. With the SWAT ArcView GIS Patch applied, the simulated flow values are almost same irrespective of the number of subwatershed delineated while the simulated flow values changes to some extent without the SWAT ArcView GIS Patch applied. However when the SWAT ArcView GIS Patch applied, the simulated sediment values vary 9.7% to 29.8% with four watershed delineation scenarios, while the simulated sediment values vary 0.5% to 126.6% without SWAT ArcView GIS applied. As shown, the SWAT estimated flow and sediment values are not affected by the number of watershed delineation significant compared with the estimated flow and sediment value without applying the SWAT ArcView GIS Patch.