• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.147-154
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• 2010

This study analyzed the characteristics of sediment produce by landslide triggered by rainfall. One-dimensional unsaturated groundwater model and infinite slope stability analysis were used to estimate the behavior of soil moisture and slope stability according to rainfall, respectively. Slope stability analysis was performed considering on soil depth and characteristics of trees. The results of the analysis on characteristics of sediment produce according to rainfall events showed that the sediment produce by landslide was mainly contributed to rainfall intensity and its temporal clustering. The results of the analysis on characteristics of sediment produce by extreme events showed that remaining rainfall amount of typhoon 'Rusa' was much more than that of the other extreme events, and thus this remaining rainfall was to contribute to sediment transportation. Additionally, only a small number of extreme events were found to cause most amount of sediment produce in a basin.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.4
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• pp.187-194
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• 2015

In this paper, we present an effective visual odometry estimation system to track the real-time pose of a camera moving in 3D space. In order to meet the real-time requirement as well as to make full use of rich information from color and depth images, our system adopts a feature-based sparse odometry estimation method. After matching features extracted from across image frames, it repeats both the additional inlier set refinement and the motion refinement to get more accurate estimate of camera odometry. Moreover, even when the remaining inlier set is not sufficient, our system computes the final odometry estimate in proportion to the size of the inlier set, which improves the tracking success rate greatly. Through experiments with TUM benchmark datasets and implementation of the 3D scene reconstruction application, we confirmed the high performance of the proposed visual odometry estimation method.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.9-14
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• 2005

For the understanding the locus of the Quinling-Dabie-Sulu continental collision's boundary and the underground structure of the sedimentray basin in the Yellow Sea, three dimensional density modelling is carrid out by using gravity dataset (Free Air Anomaly), which is measured by Tamhae 2, KIGAM in a period 2000 - 2002. The measured gravity anomaly in the investigations area is mainly responsed by depth distribution of the sedimentary basin. After comparing the sea-measured gravity data to CHAMP-GRACE satellite gravity data, I suggested that the high density model bodies extend mainly from the southern part of China to the middle-western part of the Korean Peninsula., which might be emplaced along the continental collision's boundary. The total volume of very low density bodies modified by modelling might be about $20000\;km^3$.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.191-211
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• 2017

Assessment of a storm is accomplished by the duration and storm area rather than a simple analysis given by the ground rain gauge stations. One of the best method for assessing storm is Depth-Area-Duration(DAD) of rainfall analysis. but existing DAD analysis method is likely to possible errors. Therefore, DAD analysis and its applicability were examined using a grid-based DAD analysis program that can reduce the possibility of errors in this study. Three spatial distribution techniques were used to analyze the applicability. Then, DAD analysis was performed using the converted grid-based rainfall data. As a result, it was possible to estimate the MAAR values by area for each duration, and showed high applicability in the rainfall data using ordinary kriging technique.

• Journal of Digital Contents Society
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• v.4 no.1
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• pp.11-21
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• 2003

In computer vision, the goal of stereopsis is to determine the surface structure of real world form two or more perspective views of scene. It is similar to human visual system. We can avoid obstacles, recognize objects, and manipulate machine using three-dimensional information. Until recently, only gray-level images have been used as input to computation for depth determination, but the availability of color can further enhance the performance of computational stereopsis. There are many models to provide efficient color system. The simplest model, RGB model treats color as if it were composed of separate entities. Each color channel is processed individually by the same stereopsis module as used in the gray-level model. His Model decouples intensity component from color information. So it can deal with color properties without defect intensity information. Opponent color model is based on human visual system. In this model, the red-green-blue colors are combined into three opponent channels before further processing.

• Tunnel and Underground Space
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• v.9 no.2
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• pp.158-167
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• 1999

There are substantial difficulties in assessing the volume of soill/rock to be excavated and the cost thereof, which is attributable to the subjective and qualitative methods of rock mass classification prevailing at the moment. This paper intends to introduce more objective and quantitative rock mass classification method easily applicable to the excavation of granites in Muakjae, Seoul. As a result of such study it is proven that Schmidt hammer and point load strength tests are fairly reliable and easily applicable to estimate and quantify uniaxial compressive strength of granitic material in Seoul. In an efforts to confirm the granitic rock mass conditions in 12 meters underground, seismic refraction surveys were made on the top of vertical exposures from where underlying rock mass conditions could be directly inspected. Rock mass boundaries determined by seismic refraction methods were found to agree within a 1m variance with visible differences in rock mass conditions in the vertical exposure beneath the test site. Thus it can be concluded that detailed geotechnical mapping on cutting slopes is a most efficient, dependable and cost-effective technique in assessing likely excavation conditions of shallow granitic mass in Seoul.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.313-321
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• 2008

Recently in Japan, fracturing was observed on the diagonal member of a through truss bridge at the boundary region with the concrete slab. Local corrosion damage where the diagonal member was enclosed in the concrete slab is an important factor in the fracture. In this study, accelerated exposure tests were carried out on concrete-steel model specimens simulating steel members at the boundary with concrete. Fatigue tests were then performed on the corroded model specimens. Accelerated exposure tests of the S6-cycle, which is carried out on the model specimens for 150, 300, 450 and 600 da ys. Their surface geometry was then measured. From the accelerated exposure test results, change in maximum and mean corrosion depths was determined according to the testing periods. The effect of local corrosion on fatigue strength was also presented based on the fatigue test results.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.883-891
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• 2002

The chloride penetration in concrete structures is influenced by many factors such as types of cement and admixture proportion. Therefore, the effects of these factors on chloride diffusion must be correctly considered. The conventional diffusion analysis also neglected the existence of reinforcing bar in concrete structures. The purpose of the present paper is therefore to investigate the effect of reinforcing bar on the chloride diffusion in concrete structures. For this purpose, a comprehensive finite element analyses have been conducted to obtain chloride penetration profile. The results indicate that the chlorides are accumulated in front of a reinforcing bar and that the accumulation is much larger for the case of large diameter bars. The higher accumulation of chloride at bar location causes much faster corrosion of reinforcing steel. It can be concluded from the present study that the effects of reinforcing bars must be considered in chloride diffusion analysis for more realistic prediction of durable life of concrete structures.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.261-268
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• 2004

Corrosion of reinforcement is the main cause of damage and early failure of reinforced concrete structures. The corrosion is mainly progressed by the chloride ingress. In this paper, an experimental study is executed to investigate the effect of concrete properties and testing methods on the coefficients of chloride diffusion. Also, it is surveyed the relationship between total chloride and free chloride in concrete. According to this experiment results, W/C ratio and testing method affect chloride diffusion coefficient of concrete. As W/C ratio is increased, diffusion coefficient in concrete is also increased. Diffusion coefficient obtained by each testing method show the different values, respectively. The model equation of diffusion coefficient with W/C ratio is proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2C
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• pp.69-77
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• 2012

In general, geothermal energy pile and horizontal ground heat exchangers are installed in shallower depths than conventional vertical ground coupled heat pumps. Consequently their heat exchange performance is strongly governed by thermal conductivity of soil layer. Previous studies have shown that the thermal conductivity of soil above ground water table significantly affects the heat exchange rate because of partially saturated condition in soil and consequent variation of soil thermal conductivity. This paper presents a study result on the prediction of thermal conductivity of weathered granite soils. For weathered granite soils sampled from 5 locations, thermal conductivity tests were conducted with varying porosity and degree of saturation. The existing thermal conductivity models in literatures appeared inappropriate to the weathered granite soils. Hence, an empirical equation was proposed in this paper and its validity was examined by applying it to thermal conductivity test results obtained for weathered granite soils in this study and from literatures.