• Structural Engineering and Mechanics
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• v.72 no.2
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• pp.275-291
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• 2019

In a super-large underground with "large span and high side wall", it is buried in mountains with uneven lithology, complicated geostress field and developed geological structure. These surrounding rocks are more susceptible to stability issues during the construction period. This paper takes the left bank of Baihetan hydropower station (span is 34m) as a case study example, wherein the deformation mechanism of surrounding rock appears prominent. Through analysis of geological, geophysical, construction and monitoring data, the deformation characteristics and factors are concluded. The failure mechanism, spatial distribution characteristics, and evolution mechanism are also discussed, where rock mechanics theory, $FLAC^{3D}$ numerical simulation, rock creep theory, and the theory of center point are combined. In general, huge underground cavern stability issues has arisen with respect to huge-scale and adverse geological conditions since settling these issues will have milestone significance based on the evolutionary pattern of the surrounding rock and the correlation analyses, the rational structure of the factors, and the method of nonlinear regression modeling with regard to the construction and development of hydropower engineering projects among the worldwide.

• Spatial Information Research
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• v.21 no.1
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• pp.45-52
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• 2013

Recently 3D surveying is recommended to manage underground facilities systematically before refilling of site operation. As the demand of realtime localization increases, cost reduction and consistent data construction which are realizable by using one man surveying method with unmanned target, are necessary for constructing DB of all sorts of the underground facilities with more speediness and correctness. This study sets a goal to develop a new type of surveying target which allows realtime localization to be performed by one man, through making an optimum reflector(triangle, quadrangle, and semispherical shape) by using the retro-reflection principle of optical prism which is being used for surveying currently. The new surveying target makes realtime surveying possible. To check reliability of its data, the accuracy is compared with surveying coordination of total station for each type in a quantitative method. In the result, the usefulness of the reflector for Underground Facilities localization is proved. Thus the foundation for underground DB construction conducted by one man is established for acquisition of 3D location information in more efficient way through using unmanned target.

• Spatial Information Research
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• v.18 no.1
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• pp.19-26
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• 2010

It is important to manage the underground facilities efficiently because they are directly related to the convenience and safety of citizens. But the fact that the different agencies take on a role of managing the underground facilities respectively makes it impossible. So Korean government has exerted great efforts to solve this problem through several projects. Korean government expects that the ubiquitous technologies such as sensor and wireless communication in the domain of the underground facilities management will be useful. It is main duty of u-City Management Center to monitor several situations about the underground facilities using ubiquitous technologies. But there is no consensus about what concrete situations it has to monitor even though u-cities under construction. Because local governments or related companies are in charge of carrying out these roles yet, there is no legal basis on which to do these tasks by the center. And it is needed to develop new technologies for u-services efficiently. Because technologies for u-service are vast, various and converged, so it necessary to develop them according to priority or in cooperation with other developers. In this paper, we classify the monitoring items for each facility which were investigated by a recent research. It is expected to make use of defining the role of the center and developing technologies with u-service.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.77-87
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• 2021

Several studies have been conducted to analyze, predict, and prevent the risk of ground subsidence occurring in urban areas. Nevertheless, there is insufficient research effort on risk analysis that utilizes the correlation between the density of underground structures (i.e., the spatial quantity of buried objects installed in the ground around the interested area) and the occurrence of ground subsidence. In this paper, a study was conducted to analyze the line density of underground structures using GIS-based spatial information data, and to link this with the recorded ground subsidences. An optimization algorithm was developed to maximize the correlation between the line density of 29 recorded ground subsidences and 6 types of underground structures that occurred between 2010 and 2015 for the analysis area. The concept of normalized line density was also proposed for the analysis. The normalized line density of the analysis area was divided into five grades (Grade 1: lowest, Grade 5: highest). When the optimization algorithm was applied, the case where the normalized line density was Grade 4 or higher at the location of the recorded ground subsidences was about > 80%. It is thought that the density analysis result of underground facilities can be applied to the ground subsidence risk analysis by using the proposed optimization algorithm.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.10a
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• pp.58-59
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• 2004

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.288-290
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• 2010

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.105-115
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• 2012

Today, the domestic construction area has changed from the ground development area to the underground space development area. In addition, the problems of sprawling development and environmental pollution in the process of developing underground space have become significant. In the circumstances, it is expected that the use of underground space information, which helps to understand underground space, will be on the sharp rise. However, the underground information in Korea is separately established and managed by each institution, and it is difficult to use the information in an integrated way. Therefore, at the time when the information on underground space is integrated, it is required to perform the integrated DB standardization in order to establish the integrated infrastructure of underground space information. In this work, this researcher studied a plan of using the standardization of the integrated infrastructure of underground space information. As a result, this work suggested standardization of each geologic stratum, standardization of unit systems, and standardization of the connection of underground space information regarding the standardization contents of underground space information integration. To examine its availability, this researcher conducted a questionnaire survey with experts of each institution. As a result, the suggested plan was found to be have high availability.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.483-490
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• 2021

Due to the recent increase in various problems from underground development in urbanized areas, accurate underground facility information management is highly needed. Therefore, in this study, in order to utilize the Integration Map of Underground Goespatial Information in real time on-site, the function of comparing the mutual location of the GPR (Ground Penetration Radar) sensing data and the Integration Map of Underground Goespatial Information, and function of analyze underground facilities, and function of converting surveying data into a shape file through position correction & attribute editing in a 3D space, and the function of submitting the shape file to the Integration Map of Underground Goespatial Information mobile center was defined and developed as a program. In addition, for the on-site application test of the development program, scenarios used at the underground facility real-time survey site and GPR exploration site were derived, and four sites in Seoul were tested to confirm that the use scenario worked properly. Through this, the on-site utilization of the program developed in this study could be confirmed, and it would contribute to the confirmation of the quality of Shape-file and the "update automation" of "Integration Map of Underground Goespatial Information". In addition, it is expected that the development program will be further applied to the Underground Facility Map's Accuracy Improvement Diffusion Project' promoted by the MOLIT (Ministry of Land, Infrastructure, and Transport).

• Spatial Information Research
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• v.11 no.3
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• pp.203-212
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• 2003

An integrated 3D GIS-based approach for understanding underground environment is proposed and applied to a land subsidence in densely populated region. Bedrock and geological discontinues were treated as main factors in this study. Because land subsidence in this study area was caused by cavity owing to dissolved limestone in percolating ground water. Ground was classified according to bedrock types using a clustering method and geological information, N value, and RQD value of boreholes were visualized and integrated by 3D-GIS. Therefore it was possible to recognize underground space easily and analyze the ground information effectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.2
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• pp.109-118
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• 2022

GPR (Ground Penetrating Radar), developed as a technology for geotechnical investigations such as sinkhole exploration, was used limitedly as a method to resolve undetectable lines in underground facility exploration. To improve the accuracy of underground facility data, the government made it possible to explore underground facilities using a non-metallic pipeline probe from July 2022. However, GPR has a problem in that the exploration rate is lowered in the soil with high moisture content, such as soft soil, such as clay layer, and there is a lot of variation in long-term accuracy. In this study, as a way to improve the accuracy of exploration considering the characteristics of GPR and the environment of underground facilities, we propose a GPR exploration method for underground facilities using permittivity constant correction and pattern analysis of GPR image data. Through this study, the accuracy of underground facility exploration and high reproducibility were derived as a result of field verification applying GPR frequency band and heterogeneous GPR.