• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.315-316
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• 2003

차량의 통행이 빈번한 기존 아스팔트 도로는 연속적인 차량의 하중에 의한 스트레스로 하중을 받을 때마다 아스팔트도로 층의 강도와 안정성이 떨어지면서 균열이 발생하고 이 균열이 아스팔트 도로 상층부까지 전달되는 반사균열이 발생한고, 열팽창과 수축의 반복에 기인하는 상부의 아스팔트 층의 피로에 의한 균열이 발생한다. 따라서 아스팔트 도로의 반사균열을 억제하고, 아스팔트의 소성변형에 의한 rutting현상을 억제하여 아스팔트의 도로보수 주기를 연장하여 도로상에서의 잦은 보수에 의한 자동차의 정체현상을 줄이고 도로유지에 소요되는 비용을 절감하기 위해서 아스팔트 도로를 설치할 때 아스팔트를 보강시켜주는 geogrid의 사용이 보편화 되고 있다. (중략)

• Tunnel and Underground Space
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• v.22 no.1
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• pp.22-31
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• 2012

In this study, scaled model tests were performed to investigate the stability of an asymmetrical twin tunnels constructed in rock mass comprising alternating layers of sandstone and shale. Each of tunnels had a differently shaped section, where the one was already constructed tunnel including lining structure but the other was planned to be under construction. Four types of test models which had respectively different pillar widths and loading conditions were experimented, where both crack initiating pressures and deformation behaviors around tunnels were investigated. The cracks of pillar mainly began to appear at the interfaces of alternating layers, following additional shear displacement between layers was confirmed as one of the most important factors of pillar failure in case of the model of pillar width 0.5D. The models with shallower pillar widths proved to be unstable because of lower crack initiating pressures and more tunnel convergences than the models with thicker pillar widths. The failure and deformation behaviors of tunnels were also dependent on the loading conditions, where the model of coefficient of lateral pressure 1.0 was more stable than the other model. Futhermore, the results of FLAC analysis were qualitatively coincident with the experimental results.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.207-213
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• 1998

A study was conducted to determine the characteristics of acoustic emission(AE) events generated by the expansive cement induced rock fracturing. The dominant frequency and the maximum amplitude of the AE events are changed in relation to the rate of expansive pressure development in the hole. The dominant frequencies are in the range of 150∼230kHz for the small hole tests and 400∼500kHz for the large hole test. The maximum amplitudes are in the range of 0.015∼0.050cm/sec and 0.025∼0.064cm/sec, respectively. The fact that AE events of higher amplitude with higher frequency on the large hole test and lower amplitude with lower frequency on the small hole tests were detected, may strongly imply that the amount of energy consumed for a macro-crack in both tests may be similar. The expansive cement induced crack propagates stably without any distinguished event having higher amplitude and this implies that a macro-crack is a result of stable growth of micro cracks.

• Korean Journal of Labor Studies
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• v.14 no.2
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• pp.169-200
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• 2008

노동계급은 다양한 형태의 내적 이질성을 지니고 있으며, 신자유주의 경제정책과 구조조정 과정에서 고용형태에 따른 이질성은 계급균열로 발달하며 노동계급 내적 이질성 논의의 핵심을 구성하게 되었다. 국내의 선행 연구들도 정규직과 비정규직 사이의 물질적 존재조건의 양극화 추세와 사회적 관계의 위계적 배제적 성격을 확인해 주고 있다. 하지만 정규직과 비정규직 사이의 계급균열이 극복되고 노동계급의 내적 통합과 계급형성 과정을 이룰 수 있는지에 대한 논의로 발전하지는 못했다. 본 연구는 계급균열의 극복과 노동계급 통합의 가능성을 검토하기 위해 계급균열의 핵심인 비정규직 노동자 문제를 둘러싼 정규직 비정규직의 의식 수준의 비교연구를 실시한다. 본 연구는 민주노총 공공운수연맹 노동조합원들에 대한 설문조사와 심층면접 연구를 통해 계급균열의 존재를 확인하고 그 원인과 의미를 분석하였다. 첫째, 정규직과 비정규직 노동자들은 비정규직 문제에 대한 인식을 공유하고 있지만 구체적 해결책에 대해서는 입장 차이를 보임으로써 고용형태에 따른 계급균열은 존재하며, 경제위기 이후에도 해소되지 않고 고착화되고 있음을 확인시켜 주었다. 둘째, 고용형태에 따른 계급내적 균열이 비정규직 문제 인식과 추상적 원칙 수준에서는 유의미한 의식 차이를 보이지 않지만 비정규직 문제 해결을 위한 구체적 해결책에 대해 유의미한 입장 차이를 보이는 것은 정규직과 비정규직 사이의 물질적 이해관계의 차이 때문이다. 정규직 노동자들은 비정규직 노동자들의 고용안정성과 노동조건의 개선을 허용하더라도 자신들의 이해관계가 위협받지 않는 수준에서 이루어져야 한다고 보는 것이다. 셋째, 정규직 노동자들이 추상적 원칙 수준에서는 비정규직 노동자들과 동질성을 보이지만 구체적 대안에서 차별성을 보이는 것은 정규직 노동자들의 의식의 양면성을 표현하는 것이며, 물질적 이해관계에 기초한 개인적 수준의 합리성과 계급적 원칙에 기초한 계급적 수준의 합리성이 갈등하고 있는 것이다. 넷째, 정규직 노동자들의 주관성 속에서 개인적 합리성과 계급적 합리성이 갈등하는 정도는 노동조합 가입 여부 및 소속 노동조합의 정체성, 즉 이익집단 정체성 혹은 계급조직 정체성에 의해 결정된다. 여기에 계급조직 정체성을 지닌 민주노조들이 노동계급 계급균열을 극복하고 계급형성을 이루는데 기여할 수 있다는 실천적 함의가 있다.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.111-119
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• 1999

The purpose of this study is the simulation of discontinuous rockmass and identification of characteristics of discontinuity network as a branch of the study on characteristics of groundwater system in discontinuous rockmass for evaluation of safety on disposal site of radioactive waste. In this study the site for LPG underground storage was selected for the similarities of the conditions which were required for disposal site of radioactive waste. Through the identification of hydraulic properties. characteristics of discontinuities and selection of discontinuity model around LPG underground storage facility. the applications of discrete fracture network model were evaluated for the analysis of pathway. The orientation and spatial density of discontinuities are primarily important elements for the simulation of groundwater and solute transportation in discrete fracture network model. In this study three fracture sets identified and the spatial intensity (P$_{32}$) of discontinuities is revealed as 0.85 $m^2$/㎥. The conductive fracture intensity (P$_{32c}$) estimated for the simulation area around propane cavern (200${\times}$200${\times}$200) is 0.536 $m^2$/㎥. Truncated conductive fracture intensity (T-P$_{32c}$) is calculated as 0.26 $m^2$/㎥ by eliminating the fracture with the iowest transmissivity and based on this value the pathway from the water curtain to PC 2. PC 3 analyzed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.150-159
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• 2011

The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.651-659
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• 2011

With the increase in the thermal power output of recently developed nuclear power plants, the applied forces and moments are increased in some piping systems, so that the leak-before-break (LBB) application criteria would not be satisfied in those pipes. In this paper, we present a method for obtaining the additive LBB margin in the pipes by considering the nonlinearity of the crack and material properties. Finite element analysis and the moment-rotation equation of beam theory were used to calculate the nonlinearity of the crack and material properties. Moreover crack stability analysis was performed using the method proposed in this study. The LBB margin was increased effectively through consideration of the nonlinearity of the crack and material properties in the pipe.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.211-221
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• 2003

At Aspo hard rock laboratory in Sweden, an in-situ heater experiment called "$\"{A}"{s}"{p}"{o}$ Pillar Stability Experiment (APSE)" is prepared to assess capability to predict spatting and stability in a rock mass between deposition holes for radioactive waste. To Predict reasonably fracturing process at rock pillar under a planned configuration before testing, a boundary element code FRACOD has been applied for modelling. The code has been improved to simulate explicitly fracture evolution both at rock boundaries and in intact rocks. A new inverse stress reconstruction technique using boundary element has been also developed to transfer stress field by excavation and thermal loading into the FRACOD model. This article presents the results from predictive modelling far the planned in-situ test condition. Excavation induced stresses might cause slight fracturing in the pillar walls. Typical shear fractures have been initiated and propagated near central pillar walls during 120 days of heating, but overall rock mass remained stable under the considered configuration. The effects of pre-existing joints and properties of fractures are also discussed. It is found from the results that FRACOD can properly model essential rock spatting and propagation at deep tunnels and boreholes.at deep tunnels and boreholes.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.75-86
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• 1996

A fatigue life prediction program for multiple planar surface cracks in finite plates and T-fillet joints, based on linear elastic fracture mechanics was developed. This prediction technique include the crack coalescence, mutual interation and the stress intensity concentration effect in welded joints. Total of 44 cases were compared with lida's and Vosikovsky's experimental results and it was found that the present method was a reasonable tool for the predictioin of fatigue life.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.185-196
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• 1998

이 논문은 직사각형 단면을 갖는 철근콘크리트 보에서 휨전단균열(Flexural-Shear Crack)이 원인을 규명하기 위해 모두 16개의 보를 실험한 결과를 기술한 것이다. 실험에 이용된 콘크리트보는 전단균열에 영향을 준다고 생각되는 몇 가지 요소를 인위적으로 소거 도는 고립되도록 특수하게 제작된 것이다. 이러한 특수보의 실험결과를 같은 재원을 갖는 보통의 정상보의 결과와 직접 비교하여서 그 차이를 분석함으로써 휨전단 균열의 발생원인을 규명하였다. 그 결과, 일반적인 콘크리트보에서의 휨전단균열 발생은 철근과 콘크리트의 경계면의 부착현상과 매우 밀접한 관련이 있는 것으로 나타났다. 또한 발생된 휨전단균열의 안정성은 주철근을 따라 발생되는 수평균열의 크기에 직접적인 영향을 받고 있는 것으로 나타났다. 본 연구에서 나타난 몇 가지 사실은 현재 사용중인 전단설계규준의 근본을 이루는 전단 위험단면개념과는 상반되는 것도 있었다. 실험에서 알아낸 사실을 근거로 전단파괴기구에 대한 새로운 가설을 제안하였다. 이 새 가설은 지금까지 잘 설명되지 않은 휨전단균열의 발생과 진행에 대한 원인 및 과정을 상당히 잘 설명해주고 있다고 생각된다.