• Journal of Wetlands Research
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• v.12 no.3
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• pp.57-65
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• 2010

This study was conducted to present primary data on the change of the physical characteristics of reservoir sediments for understanding the sedimentation. The records of the annual summation of the precipitation of >50mm per day (AP50) were compared with changes of bulk density, organic matter, mean grain-size, and sand ratio in sediment cores sampled from three reservoirs without dredging record. Reservoir sediments, characterized by mineral soil, contained organic matters originated from the debris of terrestrial plants, and changes of organic matter were related to changes of grain-size flowing into reservoirs when sediments of fine sandy loam showed 10% of organic matter contents. Rapid changes of grain-size and sand ratio in the sediment cores were associated with the increase and decrease of precipitation, and fluctuation of water level and water flow in reservoirs might have influenced on the formation of sediments in reservoirs. Records of AP50 suggested that sediments could accumulate more than about 30 within the short period of 10 years. The accumulated sediments in a short time can reflect the effect of natural and anthropogenic events on the physical characteristics of sediments.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.303-309
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• 2008

A probability of slope hazards was predicted at a natural terrain around the stone relics of Jinjeon-saji area, which is located in Yangyang, Kangwon Province. As the analyzing results of field investigation, laboratory test and geology and geomorphology data, the effect factors of landslides occurrence were evaluated. Also, the landslides prediction map was made up using the prediction model by the effect factors. The landslide susceptibility of stone relics was investigated as the grading classification of occurrence probability. In the landslides prediction map, the high probability area was $3,489m^2$ and it was 10.1% of total prediction area. The high probability area has over 70% of occurrence probability. If landslides are occurred at the predicted area, the three stories stone pagoda of Jinjeon-saji(National treasure No. 122) and the stone lantern of Jinjeon-saji(Treasure No.439) will be collapsed by debris flow.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.5
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• pp.39-47
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• 2016

The houses are formed in the lower part of the mountain slope face in most agricultural areas of Korea, and old residents accounting for a large portion of the agricultural populations cannot respond to the evacuation quickly when the landslide happens, and the possibility the life damage occurs is high. Therefore, it is urgent to arrange the measure on this. This study is intended to develop the personal disaster evacuation apparatus that can be installed in the house to minimize the life damage by the landslide and to develop the self-initiative evacuation apparatus. This study suggested the load applicable to the personal disaster evacuation apparatus by quantitatively analyzing the effect of the load of rockslides and avalanches caused by the landslide on the structure. Also, the material property of materials was calculated through the tension and bending intensity test after making the specimen of glass fiber reinforced plastic (GFRP) member. The load weight and material property drawn from this study can be used as the basic material for the stability analysis of the personal disaster evacuation apparatus.

• Journal of Forest and Environmental Science
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• v.29 no.3
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• pp.237-248
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• 2013

The legal basis for the systematic prevention and response to landslide hazards, and the rehabilitation of landslide-hit areas, was established through the amendment of the Forest Protection Act in August 2012. The most noticeable amendment to the Act is the inclusion of clauses associated with the designation and management of landslide-prone zones (including debris flow-prone zones). In this paper, we (1) introduce the clauses related to the designation and management of landslide-prone zones that were included in the amended Forest Protection Act, (2) examine their significance by reviewing the present status of related domestic laws and structural countermeasures such as sediment check dams for sediment-related disaster prevention, and (3) suggest the future directions of the procedure for the designation and cancellation of such zones, and their maintenance and institutional aspects. The establishment of an institutional device for the designation and management of landslide-prone zones has great significance in the aspect of (1) the establishment of a comprehensive management and prevention system for potential landslide-prone zones in forested areas where the hazard risk has been poorly recognized as compared with the flood risks in lowlands, and (2) the establishment of the basis for overcoming the limits of structural countermeasures according to limited budgets. To develop the designation and management system for landslide-prone zones, not only must present problems be addressed, but a cooperation system between the administration and local residents must also be established.

• Journal of Forest and Environmental Science
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• v.29 no.3
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• pp.226-236
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• 2013

Recently check dam construction number have been increased by becoming known that effectiveness in the control of the landslide and debris flow. However, check dam management standards are not setting yet. Therefore, this study was carried by provide a basic data for the check dam management and inspection in the Gangwondo. The followings are the results of safety inspection on the 274 check dams, which are located in mountain streams, Gangwondo, Republic of Korea. 1. It was determined that, of 274 check dams inspected, 267 check dams (97.4%) generally had a safe condition but 7 check dams (2.6%) had a bad condition that repair and/or complementary measures are required. 2. The check dams with a bad condition had the ages greater than approximately 20 years. This result should be reflected to future stream management strategy including a timing of the specific inspection for durability of check dams. 3. Our finding suggests that the safety inspection of check dams is able to provide basic information required to maintain their own functions, and thus it should be widely applied to stream management strategy against to sediment-related disasters in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.736-744
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• 2009

The abrupt failure of slope caused by a concentrated rainfall would be a disaster in this country. Specially, the soil slope may be collapsed by the rainfall seepage, however, there is not much information for the mechanism of slope failure during rainfall. As analyzing the stability of slope by rainfall, the conventional method is to put the ground-water level on the surface of slope. However, it may provide the over-reinforcement for the slope stability. Futhermore, although over-reinforcement for the slope was fulfilled, the possibility of potential slope failure still exists. In this study, the slope stability by the conventional design method and the causes of unstable slope during rainfall were investigated. To analyze the slope stability by rainfall, the computer program SEEP/W for the analysis of seepage was used. As changing the intensity and duration of rainfall in SEEP/W, the analysis were performed. After completion of analysis, the porewater pressure data from SEEP/W was applied to SLOPE/W. As a results of this analysis, it is not reasonable that the groundwater level is going up to the surface of slope during rainfall. Therefore, the conventional reinforcement for the slope stability is not obvious to satisfy the criterion safety factor during rainfall. The reasonable counterplan is to install drainage hole on the surface of slope in order to prevent erosion and debris flow.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.316-321
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• 2007

The casualties due to slope failures such as landslide, rock fall, debris flow etc. are about 24% in total casualties caused by natural disasters for the last 10 years. And these slope failures are focused in the season in which typhoon and torrential rain take place. Not much attention, however, have been put into landslide mitigation research. Meanwhile, USN(Ubiquitous Sensor Network) forms the self-organization network, and transfers the information among sensor nodes that have computing technology ability. Accordingly, USN is embossed a social point technology. The objective of this paper is to develop a prototype system for slope failure monitoring using USN technology. For this we develop module that collects and change slope movement data measured by two tiltermeter and a tension wire, store transferred data in database. Also we develop application program that can easily analyze the data. We apply the prototype system to a test site at KICT for testing and analyzing the system's performance.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.322-329
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• 1999

The hydrodynamic theory of dentin sensitivity states that movement of tubular contents or tubular fluid, in either direction of dentinal tubule, causes dentin sensitivity. A corollary of that theory is that anything that can decrease dentinal fluid movement or dentin permeability should decrease dentin sensitivity. A wide variety of physicochemical methods have been used to reduce the permeability and sensitivity of exposed dentin. The purpose of this study was to evaluate the ability of 4 kinds of clinical desensitizing agents(2% NaF, 30% Potassium oxalate, MS Coat$^{(R)}$, Tubulitec system$^{(R)}$) to reduce the rate of fluid flow through dentin in vitro. Sixty coronal dentin discs, 1mm in thickness, were prepared from extracted third molars, free from decay and wear. Dentin discs were treated with 3% EDTA(Tubulicid Plus$^{(R)}$(Dental Therapeutics AB, Sweden)) to remove the smear layer and debris occluding the tubular orifices. After placing the discs in a split chamber device, the rate at which physiologic saline solution could filter across dentin under 150cm $H_2O$ hydrostatic pressure was measured. The occlusal side of the discs were then treated with MS Coat$^{(R)}$, 2% NaF, Tubulitec system$^{(R)}$, and 30% Potassium oxalate, and the filter ratio of the saline solution was measured again. The following conclusions were drawn : 1. Hydraulic conductance which was measured after the application of desensitizing agents was decreased in all the groups(p<0.05). 2. % change of hydraulic conductance was compared but no significant difference was found among the four desensitizing agents(p>0.05). 2% NaF, 30% Potassium oxalate, MS Coat$^{(R)}$ and Tubulitec system$^{(R)}$ decreased the permeability of dentin. It is considered that above four agents can be used in treating the hypersensitive teeth.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.137-146
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• 2014

The geology of the study area which is located in Samkoe-dong, Dong-gu, Daejeon city comprises black slate, limestone, and pebble-bearing phyllitic rock as meta-sedimentary rocks; and biotite granite and quartz porphyry intrusions. Face mapping revealed sliding in three or four sites of contained coaly slate, where the dip of the foliation and other discontinuities is parallel to the surface slope. The cause of the slope sliding is this parallelism as well as the swelling of the coaly slate when wet. In contrast, the slop on the opposite side of the road is relatively stable because the dip of the foliation and other discontinuities are oblique or normal to the surface slope. To ensure slope stability, a cut-and-cover tunnel was designed and constructed for the new road.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.23-33
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• 2006

In this study, application potential of SINMAP, a GIS-based landslide hazard mapping tool, is evaluated through a case study. Through the application to the severe landslide events occurred during a heavy storm in 1991 on the Mt. Dalbong area about 78 kilometers south from Seoul, SINMAP successfully spotted most landslide sites. The effects and proper ranges of three calibration parameters of SINMAP, i.e. the soil internal friction angle, the combined cohesion of tree roots and soil, and T/R, were examined through comparison of predicted landslides with the landslide inventory data. From the findings of this study, it seems that SINMAP could be used as an effective screening tool for landslide hazard mapping especially for mountain areas with fairly steep slopes and relatively thin soil layers.