• Tunnel and Underground Space
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• v.9 no.4
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• pp.282-283
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• 1999

핵폐기물 지하처분, 지열개발, 지하 환경의 안전과 제어 등과 관련된 문제에 있어서 암석 및 암반의 역학적 거동 외에 열·수리·화학적 상호작용에 대한 이해가 필요하다. 이미 전세계적으로 국가별로 혹은 공동연구를 통하여 열·수리·역학적 상호작용에 관하여 많은 연구가 진행되었으며 최근 화학적 상호작용에 대한 문제가 추가적으로 제기되고 있다. 특히 장기간의 지하 환경의 안정성에 미치는 중요한 요소로 크립현상과 열·수리 화학적 상호작용 연구에 대한 필요성이 제기된 바 있다. 이 중 열·역학적 상호작용에 대해서는 현장문제에 적용 가능한 만은 연구결과가 제시된 바 있으나 기타 상호작용에 대해서는 다양한시험방법과모델링으로 인하여 아직가지 통일된 의견이 제시된 바 없다. 제 2주제에는 총 92편의 논문이 접수되었으며, 이 논문들의 내용, 성격, 해석방법 등을 간략히 정리하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.315-316
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• 2010

디지털 방송시대에 새롭게 등장하는 다양한 방송수신메체를 통해 이제 방송 수신은 TV뿐만 아니라 PC, DMB 수신기, DMB 수신이 가능한 휴대폰, PDA, 네비게이션 등 다양한 방식으로 확대되었다. 이러한 방송환경의 변화는 그간 우리 방송법에 따라, 우리나라 공영방송의 주요 제작재원 및 운영자금으로 부과되어 온 방송수신료에 대한 새로운 해석을 요한다. 그럼에도 2008년 우리 헌법재판소는 일부 국민이 제기한 수신료 부과처분에 대한 헌법소원심판에서 새로운 방송수신 매체를 통해 방송을 수신할 수 있음에도 불구, TV수상기 소지자에게만 방송수신료를 부과하는 현 방식이 평등의 원칙에 반하는 것이 아니라고 주장하며, 일부 국민의 청구를 기각하였다. 이 논문은 공영방송의 기능과 방송수신료의 헌법적 의미에 비추어 볼 때, 새로운 수신 매체에 대한 수신료 부과와 관련한 위의 헌법재판소 결정례는 방송수신료의 법적 성격에만 집착한 나머지 방송수신료의 헌법적 의미에 관하여 진지한 질문과 대답이 결여되어 있고, 새로운 방송수신매체간의 차이점에 대한 세심한 분석을 결하였으며, 이론적으로는 수신료를 부가하는 것이 타당한 매체까지도 면제대상에 포함시킨 시행령을 너무 쉽게 정당한 것으로 인정하고 정책적 측면에서 면제할 필요성의 검토를 소홀히 하였다. 나아가 새로운 방송수신 매체 중 방송수신 기능이 부가적이더라도, 부가적인 한도에서 제한적으로 수신료를 지불하는 것에 대하여 검토했더라면 더욱 설득력 있는 결정이 되었을 것이라고 비판하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.19-26
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• 2002

In this paper, the nonlinear structural analysis for the composite structure of the spent nuclear fuel disposal container and the 50cm thick bentonite buffer is carried out to predict the collapse of the container while the sudden rock movement of 10cm is applied on the composite structure. This sudden rock movement is anticipated by the earthquake etc. at a deep underground. Horizontal symmetric rock movement is assumed in this structural analysis. Elastoplastic material model is adopted. Drucker-Prager yield criterion is used for the material yield prediction of the bentonite buffer and von-Mises yield criterion is used for the material yield prediction of the container(cast iron insert, copper outer shell and lid and bottom). Analysis results show that even though very large deformations occur beyond the yield point in the bentonite buffer, the container structure still endures elastic small strains and stresses below the yield strength. Hence, the 50cm thick bentonite buffer can protect the container safely against the 10cm sudden rock movement by earthquake etc.. Analysis results also show that bending deformations occur in the container structure due to the shear deformation of the bentonite buffer. The elastoplastic nonlinear structural analysis for the composite structure of the container and the bentonite buffer is performed using the finite element analysis code, NISA.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.239-244
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• 2006

Borehole radar reflection surveys were carried out in the horizontal borehole to detect EDZ while constructing the tunnel for the research facility of the nuclear waste disposal in Korea. The horizontal borehole has been bored at a length of 35 m from shelter to be parallel with the tunnel which would be planed. While the tunnel has been constructing with the explosive excavation, the borehole radar reflection surveys carried out 5 times with the interval of 2 or 4 days for monitoring EDZ. The most typical change of the reflection event resulted from the face of the wall of tunnel which had been produced newly by the excavation of the tunnel daily, EDZ has been detected with constructing images of difference between two measurement stages, and also the change of EDZ through the time has been done, which is due to the generation of crack and weakening of the rock strength of the face of the tunnel's wall near previous portion of the face of a blind end of tunnel according to explosive excavation.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.139-144
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• 2009

The microseismic monitoring system with wide range of frequency has been operating in real time and it is remotely monitored at indoor and on-site for one year. This system was constructed and established in order to secure the safe and effective operation of the KAERI Underground Research Tunnel(KURT). For one year monitoring work, total 14 events were recorded in the vicinity of the KURT, and the majority of events are regarded as ultramicroseismic earthquake and artificial impacts around the tunnel. The major event is the magnitude 3.4 earthquake which was centered around Gongju city, Chungnam Province. It means that there is no significant evidence of high frequency microseismic event, which is associated with fracture initiation and/or propagation in the rock mass and shotcrete. Three components sensor was applied in order to analyze and define the direction of vibration as well as an epicenter of microseismic origin, and also properly designed and installed in a small borehole. This monitoring system is able to predict the location and timing of fracturing of rock mass and rock fall around an undreground openings as well as analysis on safety of various kinds of engineering structures such as nuclear facilities and other structures.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.147-160
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• 2020

Unsaturated hydraulic conductivity of near-surface unconsolidated layers depends on the physical properties and water content of the unconsolidated layers. So far, many studies have been conducted on the unsaturated hydraulic conductivity of near-surface unconsolidated layers. However, researches on hydraulic conductivity of unsaturated fractured rocks have been relatively rare. In relation to the construction of a low/intermediate level radioactive waste surface-disposal facility, this study compared and analyzed van Genuchten parameters (α, n) in the laboratory and the hydraulic conductivity obtained in field tests for fractured hornfels at a radioactive-waste disposal site of Korea. The relationship between the field hydraulic conductivity and van Genuchten parameters using data from the ten depth intervals of three boreholes resulted in that the correlation coefficient (R) between the hydraulic conductivity and the van Genuchten parameter α was 0.7607, showing positive correlation whereas the R between the hydraulic conductivity and the van Genuchten shape-defining parameter n was -0.8720, showing negative correlation. Hence, this study confirmed the relationship between the field hydraulic conductivity and the van Genuchten unsaturated functions for the unsaturated fractured hornfels.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.217-228
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• 2024

During deep drilling, confined aquifers can present various challenges such as the inability to remove cuttings, rapid groundwater influx, and mud loss. Particularly in flowing well conditions, it is essential to apply the suitable mud density since the aquifer can generates an overpressurized condition. This paper proposes a method for determining the suitable mud density while drilling (SMD) through confined aquifers using mud window analysis and applies it to a case study. The minimum mud density at each depth, which represents the lower limit of the mud window, is determined by the equivalent mud density pore pressure gradient (or by adding a trip margin) at that depth. The pore pressure gradient of a confined aquifer can be calculated using the piezometric level or well head pressure of the aquifer. As the borehole reaches the confined aquifer, there is a significant increase in pore pressure gradient, which gradually decreases with increasing depth. The SMD to prevent a kick can be determined as the maximum value among the minimum mud densities in the open hole section. After entering the confined aquifer, SMD is maintained as the minimum mud density at the top of the aquifer during the drilling of the open hole section. Additionally, appropriate casing installation can reduce the SMD, minimizing the risk of mud loss or invasion into the highly permeable aquifer.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.151-166
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• 2002

Groundwater development as a means of acquiring subsidiary water resource is very important for the persistent security of water resource. Nowadays, pneumatic fracturing technology which was developed in the advanced countries is applied for increasing pumping rate and eliminating contaminants. This study gives an experimental data to clarify permeability characteristics of the single discontinuity which is newly developed or increased in aperture by the pneumatic fracturing or damage propagation of the natural barrier for the nuclear waste disposal. On the basis of understanding the relationship between permeability and hydraulic aperture the result could apply as one of the basic data for researches concerned with increasing pumping rate and eliminating contaminants. Hydraulic aperture is decreased exponentially with increasing confining pressure and proportioned to permeability in the same confining pressure. Especially, with the increasing aperture permeability of coarse- and medium- grained granite shows the more rapid increasing than that of fine- grained granite.

• 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.

• Tunnel and Underground Space
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• v.34 no.1
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• pp.54-70
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• 2024

Utilization of completed open-pit for mining waste disposal is an alternative method of tailing storage facility (TSF), which can minimize the area and cost required for the installation of TSF. However, long-term tailing disposal into open-pit has a potential risk of reducing mechanical stability of surrounding rock mass by acting as an additional load. In this research, a realistic open-pit tailing disposal scenario of 60,400 hours was established based on the case of Marymia gold mine, Australia. Mechanical stability of surface pillar between open-pit and underground stope was analyzed numerically by using Sigma/W, under different stope geometry and rock mass conditions. Simulation results showed that long-term tailing disposal into open-pit can significantly increase the failure probability of surface piller. This result suggests that mechanical stability of mine geometry should be conducted beforehand of open-pit tailing disposal.