• The Journal of Engineering Geology
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• v.26 no.2
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• pp.197-205
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• 2016

Rainfall-induced landslide disaster case histories are typically required to establish critical lines based on the decrease coefficient for judging the likelihood of slope collapse or failure; however, reliably setting critical lines is difficult because the number of nationwide disaster case histories is insufficient and not well distributed across the region. In this study, we propose a method for setting the critical area to judge the risk of slope collapse without disaster case history information. Past 10 years rainfall data based on decrease coefficient are plotted as points, and a reference line is established by connecting the outermost points. When realtime working rainfall cross the reference line, warning system is operating and this system can be utilized nationwide through setting of reference line for each AWS (Automatic Weather Station). Warnings were effectively predicted at 10 of the sites, and warnings could have been issued 30 min prior to the landslide movement at eight of the sites. These results indicate a reliability of about 67%. To more fully utilize this model, it is necessary to establish nationwide rainfall databases and conduct further studies to develop regional critical areas for landslide disaster prevention.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.235-253
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• 2018

Groundwater flow induced by cracks in a buried pipe causes ground loss in the vicinity of it which can lead to underground cavities and sinkhole problems. In this study, the ground collapse mechanism and the failure mode based on an aperture in the pipe located in cohesionless ground were investigated through a series of physical model studies. As the influence parameters, size of the crack, flow velocity in the pipe, groundwater level, ground cover depth and ground composition were adopted in order to examine how each of the parameters affected the behavior of the ground collapse. Influence of every experimental condition was evaluated by the final shape of ground failure (failure mode) and the amount of ground loss. According to the results, the failure mode appeared to be a 'Y' shape which featured a discontinuous change of the angle of erosion when a groundwater level was equal to the height of the ground depth. While in the case of a water table getting higher than the level of ground cover depth, the shape of the failure mode turned to be a 'V' shape that had a constant erosion angle. As the height of the ground depth increased, it was revealed that a mechanism where a vertically collapsed area which consisted of a width proportional to the ground height and a constant length occurred was repeated.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.367-378
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• 2018

Purpose: The objective of this study is to present a reasonable safety management of the anchored in-situ wall systems constructed in the ground conditions consisting of multi-layered soils underlain by bedrocks in the urban area of Korea. Method: Field measurements collected from collapse case histories with deep excavations were analyzed for the safety management of the wall systems supported by the earth anchors in terms of lateral displacement rates. Results: The average maximum lateral displacement rate in a collapsed zone of the in-situ wall significantly increased upon the completion of the excavation. Particularly, the collapse of the in-situ wall system due to the sliding occurring along the discontinuities of the rock produced a considerably large lateral displacement rate over a relatively short period. Conclusion: For predicting and preventing the collapse of the wall system during or after the excavation work, the utilization of the safety management criteria of the in-situ wall system by the lateral displacement rate was found to be much more reasonable in judging the safety of earthworks than the application of the quantitative management criteria which have been commonly used in the excavation sites.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.469-474
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• 2003

Talus topography is that rock clasts that is weathered is accumulated dropping in steep slope to action of gravity. Rock fall talus is formed by the accumulation of rock debris falling as individual particles from a cliff. If the collapse is produced in talus slope, it will be possible the loss of manpower and country. Despite correct access about talus is required, domestic research was scientific access about talus short. The aim of the present study is to review and compare fabric data derived from rock fall talus about orientation, distribution and morphology in Sukam area. These deposits tend to have approximately equal amounts of clasts oriented parallel and perpendicular to the dip direction of the slope. And, platy-shaped clasts dominate the proximal and intermediate parts of the talus, whereas blocky-shaped clasts is more common in the distal part.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.101-108
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• 2015

The purpose of this study was to evaluate the safety of the small reservoir, which is distributed in a rural area, based on systemic reliability. It has been estimated that safety of respective reservoir the calculation of failure probability for individual reservoirs can evaluate the safety of the reservoir of the study area. The change of safety for watershed could be figured out as that result. Probability of failure was increased from $3.90{\times}10^{-5}$ to $1.35{\times}10^{-4}$ in Naesu-inpyung reservoir, from $1.33{\times}10^{-5}$ to $4.77{\times}10^{-5}$ in Buyeon reservoir and from $4.24{\times}10^{-5}$ to $2.55{\times}10^{-2}$ in Dalakmal respectively. From the results, the collapse of the upper stream reservoir was analyzed qualitatively that may affect the safety of the reservoir on the downstream area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.81-88
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• 2001

This study proposed an analytical method to evaluate a local allowable wall thickness (LAWT) for locally thinned pipe subjected to internal pressure and bending moment. In this method, the stresses in the thinned region were calculated by finite element analysis and plastic collapse was applied as a failure criterion of thinned pipe. Using this method, LAWT for a simplified thinned pipe was evaluated with variation in axial extent of thinned area, and it was compared with allowable wall thickness provided by previous pipe wall thickness criteria. The results showed that the LAWT was lower, about 50%, than that calculated by construction code or ASME Code N-597, and it was higher, about 2 times, than that estimated by evaluation model based on pipe experiments. In addition, LAWT was decreased with increasing axial extent of thinned area and saturated with further increase in axial extent. And, the variation in LAWT with axial extent of thinned area depended on type of load, especially a magnitude of bending moment, considering in the evaluation.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.2
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• pp.39-46
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• 2011

The agricultural population, the farming, the agriculture of our country has been decreased more rapidly than those of other countries. Also, the changing speed of the rural village in Korea has shown a similar trend. By considering the urbanization process and migration state caused by the economic growth and the increasing level of relative poverty in comparison with the urban area, it has been necessary to go through the impoverishment and slum-orientation of the rural area. In our country, the rural village became old age. So, the collapse is predicted to a population shortage if such trend is continued in the village society. according to investigate, Many urban peoples have opinion that migrates to a farm village. but those not migrate to rural community. The mainly reason is low life environment. therefore it is need the plan that the urban people migrates to a rural village, and must have the plan to be engaged in the agriculture. lt was the rural-fishing New Town development project that started in 2009 for 30~40 years's urban people. This study is about characteristic and improvement of Rural-Fishing New Town development project.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.115-125
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• 1984

A comparative study was undertaken to investigate the collapse of maxillary dental arch and palate in unilateral cleft lip and palate individuals. The material for this study consisted of 39 subjects with repaired unilateral cleft lip and palate (30 males, 9 females). The measurements of unilateral cleft lip and palate individuals were compared with the measurements of normal individuals (30 males, 30 females). All the subjects were in the mixed dentition stage and the mean age was almost the same. The following conclusions were obtained. 1. A large number of the maxillary dental arch of the unilateral cleft lip and palate individuals showed ${\Omega}$-shape, and the arch length was shorter than that of normal individuals. The intermolar width did not show significant difference between cleft group and group, but the intercanine width was mcuh smaller than that of normal individuals. 2. The palate of the unilateral cleft lip and palate subjects showed shorter and shallower form than that of normal subjects. 3. The palatal area of the unilateral cleft lip and palate subjects was smaller than that of normal subjects, and the cleft side area was much smaller than the opposing side area. 4. There was no significant sexual difference in measurements of maxillary dental arch and palate of the unilateral cleft lip and palate subjects.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.87-91
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• 2000

Metal ion complex of poly(N-(2,4-imidazoly)ethyl)maleimide-alt-l-octadecene (IMO-O) polymer used to confirm the possibility of molecular device made by Langmuir-Blodgett(LB) method. Electrical properties of the metal ion complex LB film were investigated using Metal/Insulator/Metal(MIM) structure. In the surface pressure-area($\pi$-A) isotherm of IMI-O polymer, the surface pressure at collapse point has a difference due to the interaction between polymer and metal ions. And the complex between polymer and metal ions could be verified through the investigation by Raman spectroscopy. In the current-voltage(I-V) property, the conductivity change of IMO-O polymer complexes due to the kinds of metal of metal ions couldn't be observed. However, the limiting area of molecules was changed by the concentration of the metal ions and the conductivity was increased with the occupied molecular area.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.23-36
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• 2019

In this paper, field measurement of the Block Type Mechanically Stabilized Earth (MSE) wall curved section was performed, and the reinforced area of the curved part is studied through the result. MSE method has been applied to various fields because of easy construction and excellent economic efficiency, so that it can be easily access in our life. However due to lack of compaction and stress concentration phenomenon, cracks and collapse occur in the curve of MSE wall, which is important for safety. The cause of collapse is lack of research on curved section, lack of design criteria, lack of construction due to economical efficiency and shortening of construction period, insufficient compaction space. In this study, therefore, it was examined the existing design and construction standards, analyzed the cause through accident examples of the curved section of the Block Type MSE wall. As a result, the horizontal displacement of the curved section was 90% higher than that of the straight section and 60% higher than that of the concave section. In the case of the convex section in the curved section reinforcement region, the maximum displacement is shown in the H/2 section in the horizontal direction from the center of the MSE wall, and the range of influence from H is shown. In the case of the concave section, the maximum displacement is shown in the center, The minimum displacement was confirmed in H/4 section in the horizontal direction from the center of the MSE wall. As a basic study on the reinforcement area rehabilitation through the actual construction of block type MSE wall, the behaviors of the straight part and the curved part were compared and analyzed. And analyzed the reinforced area in order to reduce the damage of the stress concentration phenomenon and secure the safety.