• Proceedings of the Speleological Society Conference
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• 1996.09a
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• pp.64-64
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• 1996

석회동굴은 카르스트 지형 지역에서 지하 형성물로 나타나는 공동지역으로, 이 공동화된 공간에 2차적으로 석순, 석주, 종유석 등이 침전되어 생긴 동굴이다. 이런 카르스트 지형은 석회암 지층에서 용식작용으로 생겨나는데, 우리나라에서는 북쪽은 평안남도 동반지역과 함경남도의 남부서경지역, 황해도 서남부, 그리고 강원도 남부지역, 추가령 구조곡의 일부들이 해당한다. 그리고 남쪽은 문경 - 단양 - 제천 - 영월 - 평창 - 정선 - 삼척 - 강릉에 걸친 지역들이다. 따라서 우리나라의 석회암동굴들은 그 대부분이 조선계 대석회암통의 막동 석회암 층에 분포되고 있다.(중략)

• Tunnel and Underground Space
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• v.25 no.4
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• pp.332-340
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• 2015

Ground subsidence occurring in mine area can cause an enormous damage of loss of lives and properties, and a systematic survey should be conducted a series of field investigation and ground stability analysis in subsidence area. This study describes the results from field investigation and ground stability analysis in a limestone mine located in Cheongwon-gun, Chungcheongbuk-do, Korea. Rock mechanical measurements and electrical resistivity surveys are applied to obtain the characteristics of in-situ rock masses and the distribution patterns of subsurface weak zone, and their results are extrapolated in numerical analysis. From the field investigation and stability analysis, it is concluded that the subsidence occurrence in this limestone mine is caused mainly by subsurface limestone cavities.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.393-399
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• 2020

In this study, the subsidence behavior caused by groundwater ex-flow in a limestone cavity encountered during tunnel excavation was quantified based on numerical analysis and the effect was analyzed. Based on the groundwater level and surface subsidence surveyed at the site, a numerical analysis technique was applied to analyze the characteristics of the subsidence behavior according to the tunnel passage of the geological vulnerabilities. The results of groundwater seepage-coupled analysis were analyzed to reflect the actual ground subsidence behavior. As a result of the study, it was analyzed that the ground subsidence due to the tunnel excavation in the limestone common section(the geological vulnerable zone) was analyzed that the dramatical decrease in groundwater level was the main cause. As a result of numerical analysis, it was analyzed that the long-term cumulative settlement of the asphalt surface after the groundwater ex-flow was 76~118mm due to the reduction of the volume of the soil layer due to the decrease in the groundwater level, and the settlement amount increased as the depth of the soil layer increased.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.457-475
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• 2018

For increase of reality in numerical analysis, a blasting vibration waveform obtained from field blast operations has been directly used for input parameters of dynamic analysis in the form of vibration velocity. A numerical model was built considering the geological characteristics of underground limestone opening as well as the mining stages in this opening, and the effect of blast operations on stability of underground limestone opening was investigated by dynamic numerical analysis. The adequacy of applying the real vibration waveform to dynamic analysis has been approved from the preliminary analysis, and the dynamic numerical analysis results show that the continuous mining operation can cause the collapse of roof in openings and the active yield zone around openings. Therefore, the additional reinforcements should be applied for ensuring the stability of underground limestone openings.

• Explosives and Blasting
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• v.31 no.2
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• pp.6-13
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• 2013

Recently, complaints or environmental problems caused by the noise and dust generated from crusher of the mine and quarry are emerging. Therefore mining facilities such as crushers and mills have been installed in an underground. In order to facilitate crusher equipments in the underground, excavation of large space is required and then the stability of the large space underground structure is an important issue. In this study, the blast experiments, which use a block of the limestone, are performed. Based on the blast experiments, the numerical model was prepared and simulated using dynamic fracture process analysis code(DFPA) with considering the rising time of applied borehole pressure and microscopic tensile strength variation. Comparing the non-dimensional crack length and no-dimensional tensile strength obtained from blast experiments and numerical analyses, the input parameters of DFPA code for predicting a radial tensile crack in limestone blasting were determined.

• Explosives and Blasting
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• v.33 no.2
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• pp.15-24
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• 2015

In general, blast vibrations could make underground cavern unstable by causing relative movements between the surrounding rock blocks that are divided by discontinuities such as joints and faults around the cavern. In the study, a blast guideline was established to obtain the stability of a large-scale cavern for underground crusher room in an open pit limestone mine in Korea. The guideline was suggested in the form of a standard calculation method of the maximum charge per delay for a safe blast. The allowable level of peak particle velocity for the cavern was determined based on the result of a numerical analysis using FLAC2D. The ground vibration data required for the study was obtained from field measurements.

• Tunnel and Underground Space
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• v.33 no.2
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• pp.95-107
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• 2023

In this study, the effect of repeated traffic vibration on the long-term stability of mine openings is analyzed for re-utilization of abandoned mine galleries. The research mine in this study is an underground limestone mine which is developed by room-and-pillar mining method, and a dynamic numerical analysis is performed assuming that the research mine will be utilized as a logistics warehouse. The actual traffic vibration generated by the mining vehicles is measured directly, and its waveform is used as input data for dynamic numerical analysis, As a results of dynamic numerical analysis, after 20,000 repetitions of traffic vibration, the mine openings is analyzed to be stable, but an increase in the maximum principal stress and an additional area of plastic zone are observed in the analysis section. As shown in the changes of displacement, volumetric strain, and maximum principal stress which are measured at the mine opening walls. It is confirmed that if the repeated traffic vibration is continuously applied, the instability of the mine openings can be increased. Authors expect that the results of this study can be used as a reference for basic study on utilization of abandoned mine.

• Journal of radiological science and technology
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• v.18 no.2
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• pp.37-48
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• 1995

1) 천식 기관지 확장증에서는 기종상 음영이나 기관지가 확장된 상이 있고, 또한 미만성 범세기관지염 5예에서는 미세 반점상 음영이 전체 예에서 인정이 되었다. 2) 폐염에서는 기관지의 확장이나 점액이 고여 침윤음영이 전체 예에 나타나고 있었다. 한편, 간질성 폐염 29예에서는 반점상 음영(불균일 CT치의 상승과 내부에 작은 기관지 확장으로 작은 air상)이 보였다. 폐섬유증 19례에서는 기종상 농포상 음영이나 혈관 기관의 부정 확장, 반점상 음영이 15예로 79 %를 차지하고 있다. 만성 폐기종에서는 기종상, 다발성 농포상 음영, 고목상 혈관이 특징적인 소견이었다. 3) 속립성결핵에서는 작은 입상 음영, 폐결핵 15예에서는 공동 음영 7예, 원형의 융합음영 8예, 침윤음영, 다수의 석회화상, 혈관 기관의 부정 확장 등이 특징적이었다. Aspergillus증에서는 공동 음영 내부에 fungus ball이 보였다. 이상은 미만성 폐질환의 특징적인 CT의 이상 소견에 대해서 검토하였으나, 꼭 일치되는 것은 아니며, 기타 기초적 검사나 임상적인 경과관찰이 필요하였다. 끝으로, 대한방사선기술학회의 발전과 학회원 여러분의 건승을 기원합니다. 그리고 한국과 일본의 우호적인 학술교류가 지속되기를 희망합니다.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.399-406
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• 1999

Recently, the construction of the several highway bridges in the karst area have encountered severe problems associated with cavities and sinkholes. To solve this problems, it is important to understand the distribution characteristics of cavities in the construction site on limestone area. This paper briefly describes the different types, the distribution control factors and the infill sediment types of lime-cavities in the study area, bridge site in the karst area and propose the effective method of survey design. Cavity system may be divided into two main groups, 1)'slot and cave system'and 2)'sinkhole and cave system'. And the shape, the size and the distribution pattern of cavity are controlled by three main factors - rock type, geological structure and ground water condition. Additionally, infill sediment may be considered as one of the important design factors for foundation design and divided into four types by sediment properties. There are geophysical thechnics and geologic survey and drilling test, etc. by the survey method to interpretate characteristics of cavity system, and this methods are optimally designed at the site investigation stage.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.63-70
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• 2016

The aim of this study is the safety and an accident prevention in limestone terrain by the underground tunneling. The geology of the study area consists of a Paleozoic sedimentary sequence dominated by limestone, sandstone, shale, and carbonaceous shale. The sequence gently dips to the northeast but the joint contains steep with variable trend. A significant fracture zone is developed in the limestone and shale beds, sub-parallel to bedding, and follows in part the limestone-sandstone contact. Monitoring of groundwater levels in the area shows marked fluctuations in the water table, which repeatedly rose to a level of -4 m before sinking to -15 m. These cycles occurred in mid-May, 2007 and in early and middle June. The data indicate that these fluctuations were unrelated to rainfall that occurred during the study period. We infer that the fluctuations were associated with the development of underground karstic networks along the deep fracture zone, and overlying ground subsidence is likely related to the rapid sinking of groundwater and the associated strong downward suction force.