• Tunnel and Underground Space
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• v.30 no.5
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• pp.484-495
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• 2020

To numerically simulate the advance of EPB TBM, various type of numerical analysis methods have been adopted including discrete element method (DEM), finite element method (FEM), and finite difference method (FDM). In this paper, an EPB TBM driving model was proposed by using coupled DEM-FDM. In the numerical model, DEM was applied in the TBM excavation area, and contact properties of particles were calibrated by a series of triaxial tests. Since the ground around the excavation area was coupled with FDM, the horizontal stress considering the coefficient of earth pressure at rest could be applied. Also, the number of required particles was reduced and the efficiency of the analysis was increased. The proposed model can control the advance rate and rotational speed of the cutter head and screw conveyor, and derive the torque, thrust force, chamber pressure, and discharging during TBM tunnelling.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.1
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• pp.97-108
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• 2018

The purpose of this study is to propose the construction of a visibility analysis model, which is the basis of the analysis for landscape management on the heritage sites such as historic villages and scenic sites. Results of the visibility analysis using DEM and the visibility analysis of DSM based on 3D mapping data are compared as follows: Precision level of the extracted data was confirmed to be less than 6.5cm, based on RTK survey results produced by constructing orthoimage data and DSM from the digital data of 2cm-class GSD(Ground Sample Distance) obtained by using a small UAV(Unmanned Aerial Vehicle). As a result of comparing the visibility analysis data of Digital Surface Model (DSM) using a small UAV with Digital Elevation Model(DEM) applying the height of the building to the Digital Topographic Map, it was confirmed that more realistic visibility analysis can be accomplished by applying DSM, as the structures such as fences, trees, and houses are reflected in the topographic data. The visibility analysis model using the 3D mapping technique can efficiently obtain the constantly changing topographic information when needed, by immediately constructing the data by utilizing a small UAV. It seems to be possible to propose a reasonable analysis result for preservation management such as landscape evaluation of cultural property.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.2
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• pp.99-105
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• 2007

This research is about applying aerial photos to three-dimensional simulation of road design. Instead of existing road design approach using digital map, which inexactly represent some part of topography and landmarks, digital aerial photos are applied to three-dimensional road design to address such inexactness of the map. First of all, ortho-photos are made using aerial photos, and a digital elevation model is created by extracting DEM. Then, by applying the coordinates practically using in planar design to three-dimensional approach, this model will be much helpful in the analyses of road route and viewscape. In addition, through the use of Virtual GIS, many evaluation factors such as urban design, flora, soil, water channel or road shape, flood plan are used for examination, and the effectiveness of applying three-dimensional simulation based on such route design standard is to be reviewed. In this paper, a basic research about three-dimensional design of structures is performed, and through the three-dimensional design, some effective determination to decision-making was carried out. Hereafter, it appears some research regarding environment-friendly construction and design should be followed.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.5-12
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• 2017

Since 2000, the national geotechnical information DB has been constructed by Transport and Maritime Affairs (present Ministry of Land) and recently, it provides more than 210 thousands borehole informations through the geotechnical information DB portal systems. The initial project of underground space information computerization was begun in 2007, focusing on collecting the informations after then additional studies had been conducted to verify the precision and accuracy of collected informations in 2013~2014. In accordance with the recent initiation of the 3D integrated underground space mapping project, it is necessary to construct 3D image of the geotechnical information and evaluate the accuracy and precision of the information. Therefore, in this research, the basic information regarding the precision of the geotechnical DB is provided by kriging method and analysis of RMSE for the systematic 3D construction of geotechnical information. In addition, the elevation data errors of boring information are verified by analysis of elevation data such as boring information data and DEM data.

• Journal of the Korean Geotechnical Society
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• v.33 no.4
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• pp.5-15
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• 2017

Three-hinge failure occurs in a jointed rock slope with a joint set parallel with slope and a conjugate joint set. Limit Equilibrium Method (LEM) and Finite Element Method (FEM) which are commonly used for slope design, are not suitable for evaluating stability against three-hinge failure, and this study performed parametric study to analyze the failure mechanism and to find influence factors causing three-hinge failure using UDEC which is a commercial two-dimensional DEM based numerical program. Numerical analyses were performed for various joint structural conditions and joint properties as well as ground water conditions. It was found that pore water pressure is the main factor triggering the three-hinge failure and the mode of failure depends on friction angle of basal joint and bedding joint set. The results obtained from this study can be used for adequate and economic footwall slope reinforcement design and construction.

• Resources Recycling
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• v.27 no.3
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• pp.86-92
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• 2018

The amount of construction waste generated is steadily increasing every year, and the Law for Promotion of Recycling is enacted. However, it is difficult to use it as a recycled aggregate for concrete, which is presented in the quality standard of recycled aggregate with high water uptake and low density due to low separation of aggregate between concrete and cement paste. Therefore, in this study, a multi-stage impact crusher was used to remove mortar, which is essential for improving the quality of recycled aggregate. In analyzing the characteristics of the equipment, the spectrum of energy generated in each part between the particle and the equipment was calculated by using DEM. In order to generate an effective separation phenomenon, it was confirmed that the operation condition of 900 RPM was appropriate based on the ratio of the number of collisions (L/H) of the low energy group (L) to the number of collisions of the high energy group (H).

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.63-69
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• 2005

Interferometric Synthetic Aperture Radar(InSAR) is a rapidly evolving technique. Spectacular results obtained in various fields such as the monitoring of earthquakes, volcanoes, land subsidence and glacier dynamics, as well as in the construction of Digital Elevation Models(DEMs) of the Earth's surface and the classification of different land types have demonstrated its strength. As InSAR is a remote sensing technique, it has various sources of errors due to the satellite positions and attitude, atmosphere, and others. Therefore, it is important to validate its accuracy, especially for the DEM derived from Satellite SAR images. In this study, Real Time Kinematic(RTK) GPS and Kinematic GPS positioning were chosen as tools for the validation of InSAR derived DEM. The results showed that Kinematic GPS positioning had greater coverage of test area in terms of the number of measurements than RTK GPS. But tracking the satellites near and/or under trees md transmitting data between reference and rover receivers are still pending tasks in GPS techniques.

• Journal of Korea Water Resources Association
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• v.31 no.2
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• pp.199-208
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• 1998

This study is on the application of TOPMDEL(Topographic based hydrologic model) Which is a distributed rainfall-runoff model to the flood runoff analysis. The test area was Wichun experimental catchment site which is mountainous mid-area (Dongok, 33.63$\textrm{km}^2$ and Goro, 109,725 $\textrm{km}^2$) and being operated by the Ministry of Construction and ransporation. A three-dimensional digital elevation model(DEM) map was constructed using a physiographic map(1/25,000) and GIS software, Arc/Info, was used to the analysis of geofraphic factors. The topographic index of Dongok and Goro subcatchment was similar. As a results of the analysis, the model was validated that the simulated peak flow of a flood runoff was fit to the observed data. For the analysis of the effects of grid size, Dongok subcatchment was divided into 100,120-,240 m grid and Goro subcatchment was divided into grid and 120,200,350 m grid. It was shown that the peak flow increased in proportion to the increases of the grid size, but peak times were constant regardless of the grid size in both of the watershed.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.29-37
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• 2017

In this study, we analyzed the impacts of land surface characteristics on spatially and temporally distributed soil moisture values at the Yongdam and Soyang-river dam watersheds in 2014 and 2015. The soil moisture, NDVI (Normalized Difference Vegetation Index) and temperature values at the spatio-temporal scales were estimated using satellite-based MODIS (MODerate Resolution Imaging Spectroradiometer) products. Then the Pearson correlations between soil moisture and land surface characteristics (NDVI, temperature and DEM-digital elevation model) were estimated and analyzed, respectively. Overall, the monthly soil moisture values at the time step were highly influenced by the precipitation amounts. Also, the results showed that the soil moisture has the strong correlation with DEM while the temperature was inversely correlated with the soil moisture. However the monthly correlations between NDVI and soil moisture were highly varied along the time step. These findings indicated that water loss near the land surface are highly occurred by soil and plant activities as evapotranspiration and infiltration during the no/less precipitation period. But the high precipitation amounts reduce the impacts of land surface characteristics because of saturated condition of land surface. Thus these results demonstrated that soil moisture values are highly correlated with land surface characteristics. Our findings can be useful for water resources/environmental management, agricultural drought, etc.

• Journal of Korea Spatial Information System Society
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• v.3 no.1 s.5
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• pp.117-126
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• 2001

We have developed the Mobile Multi Sensor System(MMSS) for the data construction of 4S application and for basic technology acquisition of mobile mapping system in Korea. Using this MMSS, we will collect the information of road and road facilities for DB creation and also construct the Digital Elevation Model(DEM) as ancillary data in urban area. The MMSS consist of the integrated navigation sensor, DGPS & IMU, and digital CCD camera set. In the S/W aspect, we developed the post-processing components for extracting the 3D coordinate information (Spatial Information) and the client program for the MMSS user group. In this paper, we will overview the MMSS constitution and post-processing program, and introduce the utilization plan of MMSS.