• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.545-554
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• 2018

As the map paradigm shifts from analog to digital, the LOD (Level Of Detail) of spatial information needs to be redefined. In this study, we propose 4- dimensional indoor LOD model which can be used in digital map environment. For this purpose, the limitation of the previous research is derived through study of related works, and based on this, four different LODs are defined such PLOD (Position accuracy LOD) based on position accuracy, GLOD (Geometric LOD) based on shape representation, CLOD (Complete LOD) based on generalization, and SLOD (Semantic LOD) based on theme accuracy. In addition, we describe the relationships among the four different LODs, and explain how to express the indoor LOD using the four different LODs and show examples. In the future, the case studies of indoor LOD adoption for various indoor services and the study of method for applying CLOD and SLOD to each feature should be performed to verify the feasibility and validity of proposed indoor LOD.

• Spatial Information Research
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• v.14 no.3 s.38
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• pp.321-334
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• 2006

3D spatial data are of increasing interest in landscape analysis, urban planning and map services based on Web, because of its reality. But the amount of 3D spatial data are very large in comparison with 2D spatial data. Therefore it is necessary to have a efficient methods to transfer and visualize 3D spatial data. The concept of Level of Detail in Computer Graphics is effective. This paper briefly presents two LOD data models of data transmission based on the spatial data model of international standards. First, it is separated LOD model that gives a LOD level to object. Second is Selective LOD model that gives a LOD level to object's element. We compared the efficiency of 3D data transmission based on two LOD model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.2
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• pp.143-151
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• 2014

As the interest in indoor space increases, the demands for various services based on indoor space is increasing. With the demands, to construct spatial information for indoor space is also required, but there is not defined the LOD(Level of Detail) for indoor spatial data. Therefore, in this paper we classified data for indoor space data construction, and then we defined the accuracy and detail about the level of detail to provide suitable application services according to the type and representation method of each data. Most previous researches are focus on the geometrical representation, but in this paper we define a indoor LOD model based on type and representation method of data. In addition, we present applicable services with proposed LOD model and suggest a guideline for construction and application of indoor space.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.31-33
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• 2006

위치기반서비스나 텔레매틱스 등의 공간 정보에 기반을 둔 시설물 분야나 재해 분야에서 3차원 공간정보에 대한 사용이 광범위해지고, 3차원 공간 정보 생성, 구축 및 활용에 대한 연구는 더욱 더 활발히 진행되고 있다. 특히 세밀도(Level of detail-LOD)는 대용량의 3차원 공간 정보를 표현, 저장하기 위한 주요한 방법론으로 그에 관한 연구가 많이 진행되고 있는 실정이다. 본 논문에서는 서버/클라이언트 환경에서 대용량의 3차원 공간 데이터를 효율적으로 전송하기 위한 두 가지의 세일도 모델을 제안한다. 그리고 두 세밀도 모델들의 데이터전송에 대한 효율성을 비교해 보았다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.415-423
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• 2015

In this study, we present a grid refinement model in the lattice Boltzmann method (LBM) for two-dimensional incompressible fluid flow. That is, the model combines the desirable features of the lattice Boltzmann method and stream function-vorticity formulations. In order to obtain an accurate result, very fine grid (or lattice) is required near the solid boundary. Therefore, the grid refinement model is used in the lattice Boltzmann method for stream function-vorticity formulation. This approach is more efficient in that it can obtain the same accurate solution as that in single-block approach even if few lattices are used for computation. In order to validate the grid refinement approach for the stream function-vorticity formulation, the numerical simulations of lid-driven cavity flows were performed and good results were obtained.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.285-292
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• 2014

BIM (Building Information Modeling) is a new paradigm that includes construction life-cycle, and BIM has become mandatory regulation according to the Public Procurement Service since 2016, which accelerates its application. BIM is now expand from architectural field to infrastructure industry. Through pilot projects, BIM has been challenged with verification process. This trend has affected to maintenance and operation (M&O) phase of construction life-cycle. Advanced country has already published their research and result with feasibility study and guidelines. In this paper, we conduct the feasibility study to adopt BIM-based infrastructure management system. Bridges and tunnels were selected as application target, and benefit/cost ratio were used. The result shows that BIM-based infrastructure management system is feasible when the level of detail is more than "Medium" in bridge, and "High" in tunnel.

• Spatial Information Research
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• v.21 no.5
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• pp.73-82
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• 2013

In recent years, according to the increase of interests in indoor space, various researches are being carried out for the construction and services of indoor spatial information. BIM data is very useful to build indoor spatial information. Accordingly, many studies for the use of BIM data on GIS part are in progress. In order to take advantage of BIM data on GIS part, the conversion technology for building indoor data and visualization techniques are required. However, most of the previous researches are focused on the conversion technology to construct indoor spatial information by importing BIM data into GIS applications while there is few research on visualization. In this study, an indoor LOD(Level of Detail) model is proposed to apply to on indoor facility management system when indoor data was constructed based on BIM data for the linkage between BIM and GIS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.197-205
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• 2020

Compared to aerial photogrammetry, UAV photogrammetry has advantages in acquiring and utilizing high-resolution images more quickly. The production of 3D models using UAV photogrammetry has become an important issue at a time when the applications of 3D spatial information are proliferating. Therefore, this study assessed the feasibility of utilizing 3D models produced by UAV photogrammetry through quantitative and qualitative analyses. The qualitative analysis was performed in accordance with the LODs (Level of Details) specified in the 3D Land Spatial Information Construction Regulation. The results showed that the features on planes have a high LoD while features with elevation differences have a low LoD due to the occlusion area and parallax. Quantitative analysis was performed using the 3D coordinates obtained from the CPs (Checkpoints) and edges of nearby structures. The mean errors for residuals at CPs were 0.042 m to 0.059 m in the horizontal and 0.050 m to 0.161 m in the vertical coordinates while the mean errors in the structure's edges were 0.068 m and 0.071 m in horizontal and vertical coordinates, respectively. Therefore, this study confirmed the potential of 3D models from UAV photogrammetry for analyzing the digital twin and slope as well as BIM (Building Information Modeling).

• Journal of KIBIM
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• v.7 no.4
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• pp.8-20
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• 2017

When it comes to set up the BIM through the reverse engineering, the level of detail(LoD) required for finalized outcomes is different from each purpose. Therefore, it is necessary to establish some concrete criteria which describe the definition of LoDs on 3D modeling for the purpose of each reverse engineering. This research shows the criteria of the 1) positional accuracy, 2) generalization level, 3) scale level, 4) scope of description, and 5) the area available for application by classifying LoD from 1 to 6 on 3D modeling for each purpose of reverse engineering. Moreover, through applying those criteria for the 3D point cloud dataset of building made by terrestrial LiDAR, this research finds out the working hour of 3D modeling of reverse engineering by each LoDs according to defined LoD criteria for each level. It is expected that those findings, how those criteria of LoD on reverse engineering are utilized for modeling-workers to decide whether the outcomes can be suitable for their budget, applicable fields or not, would contribute to help them as a basic information.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.198-201
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• 2013

This study was carried out to develope new zoysiagrass cultivar Semil' (Registration no. 1749). Artificial crossing between the collected lines of typical Z. matrella, NM1 (collected in South Korea) and the different ecotype of Z. matrella, ASm (collected in South Korea) was made to develop a F1 hybrid plant (NM1 ${\times}$ ASm). Among the 30 progenies, (NM1 ${\times}$ ASm)-1 (Semil) showed superior performance in density rating. 'Semil' showed genetically light green color, with narrow leaf width ($2.7{\pm}0.12mm$), and low plant height ($10.3{\pm}3.7cm$), Length to lowest leaf blade of this cultivar was $1.8{\pm}0.15cm$, which may allow low mowing height upto 12 mm.