• Tunnel and Underground Space
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• v.30 no.2
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• pp.136-148
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• 2020

Nuclear power plants have been operated in Korea since 1978, thus the high-level radioactive waste (HLW) produced from the plants has been accumulated accordingly. Hence, it is urgent to secure a final repository for HLW disposal, however, siting process should be preceded, which usually takes long time, as it requires broad and precise investigation. The investigation is generally carried out in stages, which consists of multidisciplinary approaches. In this study, the case studies mainly pertaining to rock mechanics were conducted. Rock mechanical aspects required in each stage and their applications were investigated and corresponding R&D researches were presented as well. At the same time, current research status in Korea was presented, followed by a brief future research plan with regard to the site investigation. The future research aims to produce fundamental information for siting process, and the compiled cases in this study will be utilized as references in the research.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.195-212
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• 2005

Surface subsidence which occurs with several reasons, such as collapse of gangway, discharge of groundwater, compaction of weak rock mass, and tunnel excavation in shallow depth, gives rise to a serious problem in national infra-structures. In this study, therefore, the mechanism of subsidence has been examined numerically to overcome the passive approach on subsidence occurrence area. With many kinds of numerical studies, the major geotechnical parameters have been selected and the weighted values have been defined for each parameters. Also the authors developed the numerical program which can estimate the possibility of subsidence occurrence, and proposed the decision method for objective and quantitative guideline. It is anticipated that this research will be helpful to establish the hazard map on subsidence region.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.90-101
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• 2007

With increasing development of underground space, underground pumped storage power plants, which generate power by felling water in upper reservoir to lower reservoir, have been continuously constructed. For efficient and safe design, construction and maintenance or such power plants, it is very important to understand in-situ stress and the mechanical properties of the surrounding rock mass at the design stage. The power plant presented in this paper is under construction at a depth of $320{\sim}375m$. For stability evaluation of the structure, in-situ stress was measured by over-coring method. Also pressurementer test and a series or laboratory tests were performed to obtain the mechanical properties. Numerical analyses were conducted to check the efficiency of designed support patterns. The results showed that unstable areas occurred partly in the numerical model, and therefore supports were additionally applied. Finally complete stability was obtained and the following excavation has been operated successfully until now.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.143-153
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• 2016

This study analyzed the features and various applications of Bluetooth beacon technology for utilization in the mining and construction industries. Through a literature survey, the concept and version-specific features of Bluetooth were reviewed, and representative types of the Bluetooth beacon-based service and its real-world applications in other fields were analyzed. Although a few previous studies that used the Bluetooth Classic (the old version of Bluetooth technology) in the mining industry have been reported, no mine site could be found where the Bluetooth beacon technology was utilized. In the construction industry, this study could find a site where the Bluetooth beacon technology was used to improve the haulage works of construction raw materials. Since the Bluetooth beacon technology has low power consumption and is easy to integrate with smartphones, it will be effectively utilized to improve the productivity and safety in the mining and construction industries.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.175-185
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• 2007

When filling material such as clay is included along the discontinuity, it may cause instability on a slope even if the direction of discontinuity works in a positive way. In the study area, slope sliding occurred at the boundary between a clay filling material and weathered soil because the physical properties differ across the boundary; and this is very similar to the situation where foliation in a rock works as a weak zone during a structural behavior, causing an inter-layer slip. In most analysis, if there exists a clay filling material, a single discontinuity is assumed to perform analysis. In those cases, the discontinuity is modeled as a slip surface within clay. Therefore, the characteristics of the boundary are not considered in the analysis, so that ultimately the physical property of clay usually prevails. The result of evaluating the slope stability affected by clay filling material shows the significant difference in the safety level due to the strength parameter depending on the failure type of the discontinuity by a filling material.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.289-299
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• 2008

Based on the case study on the causes for the failure of cutting slope composed of weathered rock and soil, the factors influencing the design of a cutting slope have been examined, This type of rock and soil is widely distributed on the region whose parent rock is granite. To analyze the stability of the cutting slope, the following series of progress has been conducted: (1) ground characterization by geological survey and ground investigation, (2) the safety factor examination by limit equilibrium analysis and numerical analysis and (3) the comparison and analysis of rainfall and failure history. As a result, the main factors to cause the failure is determined to be the decrease of shear strength in the upper parts whose ground condition is weakened during localized heavy rain. Moreover, the analysis indicates the failure is also closely related to the groundwater inflow path. On the base of this investigation, a reinforcement method is proposed to ensure the stability of the cutting slope.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.4
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• pp.48-58
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• 2009

In recent years, construction worker safety in construction site is important. Especially, the frequent collapse accidents have happened in tunnels, utility tunnel and underground structure, so that the importance of worker safety is greatly emphasized. It is difficult to communicate with other workers in underground space, using the current cable or wireless communicator. When the accident is occurred, it can't rescue workers. This is the reason that it has a deficiency to find a location of survivor and communicate rescure crew and field workers. In this paper we extract the optimal technical factors of USFSS(Underground Structure Field Support System) based on integrated technique of wireless communication and location awareness. And USFSS developed in this study is suited for bad environment of underground structure construction and able to track 3D position of laborer and communicate mutually.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.202-206
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• 2013

A submerged floating railway is an innovative tunnel infrastructure passing through the deep sea independent of wave and wind so that high speed trains can run on it. It doesn't depend on water depth and is cost effective due to modular construction on land. The construction period can be reduced drastically. This paper introduces the concept design of a submerged floating railway, and for securing safety, proposes a method to analyze the structural behavior of the body in case of collision with a submarine. The theory of a beam with an elastic foundation was used to calculate the equivalent mass of the body so that the perfect elastic collision could be applied to calculate the collision velocity. The maximum deformation and bending moment was analyzed based on energy conservation. To verify the results, a collision analysis using a finite element analysis code was made. Comparing the results confirmed that this simplified collision analysis method gives enough accurate deformation and bending moment to be used for actual estimation in the initial design stage.

• Explosives and Blasting
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• v.39 no.3
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• pp.24-34
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• 2021

Electronic detonators are widely used in various construction sites due to accurate delay time. Including the cases with exceeded noise and vibration from site using electric/non-electric detonator, electronic detonators are used to improve blast fragmentation or to reduce the cost of secondary partial blasting. Furthermore, the number of cases using electronic detonators are increased for reduction of the cost and construction period by maximizing operations efficiency. This case study is about applying electronic detonators on large section station, tunnel construction site which is the part of urban area GTX A project. Although it was initially planned to utilize non-electric detonators, damage was inflicted on safety-thing. We have considered blasting method using electronic detonators as solution of this problem. By applying electronic detonators, we not only satisfied environmental regulations but also prevented nearby safety-thing from getting damaged. In addition, we were able to shorten the construction period than the initial plan by conducting single simultaneous blasting on large section station, in order to ensure safe and efficient construction.

• Tunnel and Underground Space
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• v.29 no.1
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• pp.12-29
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• 2019

Permeability and its change due to a fluid injection in jointed rock mass is an important factor to be well identified for a safe and successful implementation of Carbon Capture and Sequestration (CCS), Enhanced Geothermal System (EGS) and Enhanced Oil Recovery (EOR) projects which may accompany injection-induced hydromechanical deformation of the rock mass. In this technical report, we first reviewed important issues in evaluating initial permeability using borehole hydraulic tests and numierical approaches for understanding coupled hydromechanical properties of rock mass. Recent SIMFIP testing device to measure these hydromechanical properties directly through in-situ borehole experiments was also reviewed. The technical significance and usefulness of the device for further applications was discussed as well.