• Korean Journal of Environment and Ecology
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• v.9 no.1
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• pp.70-76
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• 1995

Digital elevation model for analysing terrain of Odaesan National Park was constructed by 1：50.000 topographical map. The fifty five percent of total area is located in higher than 900m in elevation, while ninty percent of the conservation area in Pirobong is above 1,100m. In other word, seventy percent of Odaesan National Park area has the slope of more than 20$^{\circ}$and is steep mountain. The aspect of the mountain mainly turned out to be eastward and westward.

• Wind and Structures
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• v.28 no.4
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• pp.239-253
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• 2019

Accurate numericalsimulation of wind field over complex terrain is an important prerequisite for wind resource assessment. In this study, numerical simulation of wind field over complex terrain was further carried out by taking the complex terrain around Siu Ho Wan station in Hong Kong as an example. By artificially expanding the original digital model data, Gambit and ICEM CFD software were used to create high-precision complex terrain model with high-quality meshing. The equilibrium atmospheric boundary layer simulation based on RANS turbulence model was carried out in a flat terrain domain, and the approximate inflow boundary conditions for the wind field simulation over complex terrain were established. Based on this, numerical simulations of wind field over complex terrain under different inflow wind directions were carried out. The numerical results were compared with the wind tunnel test and field measurement data for land and sea fetches. The results show that the numerical results are in good agreement with the wind tunnel data and the field measurement data which can verify the accuracy and reliability of the numerical simulation. The near ground wind field over complex terrain is complex and affected obviously by the terrain, and the wind field characteristics should be fully understood by numerical simulation when carrying out engineering application on it.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.497-506
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• 2008

The needs for digital models of real environment such as 3D terrain or cyber city model are increasing. Most of applications related with modeling and simulation require virtual environment constructed from geospatial information of real world in order to guarantee reliability and accuracy of the simulation. The most fundamental data for building virtual environment, terrain elevation and orthogonal imagery is acquired from optical sensor of satellite or airplane. Providing interoperable and reusable digital model is important to promote practical application of high-resolution satellite imagery. This paper presents the new research regarding representation of geospatial information, especially for 3D shape and appearance of virtual terrain. and describe framework for constructing real-time 3D model of large terrain based on high-resolution satellite imagery. It provides infrastructure of 3D simulation with geographical context. Web architecture, XML language and open protocols to build a standard based 3D terrain are presented. Details of standard-based approach for providing infrastructure of real-time 3D simulation using high-resolution satellite imagery are also presented. This work would facilitate interchange and interoperability across diverse systems and be usable by governments, industry scientists and general public.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.493-495
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• 2010

A three-dimensional flow simulation is performed to investigate the flow field in the ski resort on complex terrain. The present paper aims to study the wind effects of mountainous terrain on the gondola safety. Strong wind happens in the ski resort on the mountain by complex terrain and it causes the dangerous accident of gondola. A digital map around the ski resort area is used to model the actual complex terrain for a 3-D analysis domain. Wind direction and speed to be used as a boundary condition are taken from local meteorological reports. The numerical results show details of the velocity distribution around a ski resort. From the results, we can suggest the modification of the installation of gondola for the safety due to strong wind.

• Journal of Korean Society of Rural Planning
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• v.11 no.1 s.26
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• pp.9-15
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• 2005

Preservation of geometrical context of terrains in a digitized format is useful in handling and making modification to the data. Digitization of three-dimensional terrain still proves a great challenge due to heavy load of context required to retain details of topological and geometrical information. Methods of simplification, restoration and multi-level terrain generation are often employed to transform the original data into a compressed digital format. However, reduction of the stored data size comes at an expense of loss of details in the original data set. This article reports on an alternative scheme for simplification and restoration of terrain data. The algorithm utilizes the fact that the terrain formation and patterns can be predicted and modeled through the fractal algorithm. This method was used to generate multi-level terrain model based on NGIS digital maps with preserving geometrical context of terrains.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.2
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• pp.291-298
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• 1995

This paper describes the test results of terrain corrections as the short wave length effect and geoid effects in gravity field modelling using Digital Terrain Model(DTM) in Korea. For a rigorous determination of terrain correction a dense grided DTM data wave prepard spacing $500\times{500m}$ was used for the computation of terrain effects. From the results obtained by the mass prism model and the mass line model, we were found that the terrain effects are large depend on the topography in the test area. It means that we should considered the terrain effects for the precise geoid determination.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.83-90
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• 1985

According to development of the areial photogrammetry, it is uneconomical to acquire the terrain information and compute the earthwork volume of each building site by a field surveying which is used recently because it is acquired much money and time. The aim in the this thesis is to acquire the terrain information using the Digital Terrain Model (DTM) to gain in the aerial photograph and compute the rapid and economical earthwork carrying out digital test. Because of being little difference between the digital test and field (site) surveying in the earthwork volume, that result is fitter in preliminary planning than in practical planning to the extent.

• Korean Journal of Remote Sensing
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• v.35 no.5_1
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• pp.715-726
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• 2019

With the increasing prevalence of high-resolution satellite images, the need for technology to generate accurate 3D information from the satellite images is emphasized. In order to create a digital terrain model (DTM) that is widely used in applications such as change detection and object extraction, it is necessary to extract trees, buildings, etc. that exist in the digital surface model (DSM) and estimate the height of the ground. This paper presents a method for automatically generating DTM from DSM extracted from KOMPSAT-3A stereo images. The technique was developed to detect the non-ground area and estimate the height value of the ground by using the previously constructed low-resolution topographic data. The average vertical accuracy of DTMs generated in the four experimental sites with various topographical characteristics, such as mountainous terrain, densely built area, flat topography, and complex terrain was about 5.8 meters. The proposed technique would be useful to produce high-quality DTMs that represent precise features of the bare-earth's surface.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.8 no.2
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• pp.17-22
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• 1990

The Digital Terrain Model(DTM) data in the Geographic Information System(GIS) needs to be interpolated for various purposes. Three interpolation methods-Bilinear, Bicubic Spline, and Gregory-Newton interpolation-were used, compared, and analyzed in terms of the visual comparison and numerical analysis in the hilly terrain and relatively flat terrain.

• Journal of Korean Society for Geospatial Information Science
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• v.1 no.2 s.2
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• pp.83-96
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• 1993

The orthophto map is seen as the form of picture with the uniform reduced scale as the current terrain map. Thus it provides a reasonable feeling of scene and is easy to be interpreted. Furthermore, digital orthophoto is currently used as the basic terrain information data of the Geo-Spatial Information System(GSIS). Therefore, the orhtophoto map has high potential use as a future terrain map. This paper studies the method of producing orthophoto map by using the digital satellite imagery data taken from SPOT satellite of France. The production of orthophoto map requires the process of generating orthophoto imagery with digital elevation model, which process is called digital differential rectification. As the final accuracy of orthophoto map depends on that of digital elevation model, the precise and efficient production method of digital elevation model should be preceded. This study investigated the method of producing digital elevation model directly from SPOT satellite imagery and generated ortho-image by resampling the original SPOT imagery through digital differential rectification. Finally, Simple orthophoto map was made by overlaying the ortho-image and the contour map from digital elevation model.