• 터널과지하공간
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• 제2권1호
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• pp.50-67
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• 1992

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2002년도 춘계학술발표회 논문집
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• pp.1-8
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• 2002

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.1-13
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• 2000

• 터널과지하공간
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• 제1권
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• pp.91-101
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• 1991

• 터널과지하공간
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• 제2권1호
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• pp.28-49
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• 1992

• Geomechanics and Engineering
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• 제23권1호
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• pp.61-69
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• 2020

The uniaxial compressive strength (UCS) of rock is a basic parameter in underground engineering design. The disadvantages of this commonly employed laboratory testing method are untimely testing, difficulty in performing core testing of broken rock mass and long and complicated onsite testing processes. Therefore, the development of a fast and simple in situ rock UCS testing method for field use is urgent. In this study, a multi-function digital rock drilling and testing system and a digital core bit dedicated to the system are independently developed and employed in digital drilling tests on rock specimens with different strengths. The energy analysis is performed during rock cutting to estimate the energy consumed by the drill bit to remove a unit volume of rock. Two quantitative relationship models of energy analysis-based core drilling parameters (ECD) and rock UCS (ECD-UCS models) are established in this manuscript by the methods of regression analysis and support vector machine (SVM). The predictive abilities of the two models are comparatively analysed. The results show that the mean value of relative difference between the predicted rock UCS values and the UCS values measured by the laboratory uniaxial compression test in the prediction set are 3.76 MPa and 4.30 MPa, respectively, and the standard deviations are 2.08 MPa and 4.14 MPa, respectively. The regression analysis-based ECD-UCS model has a more stable predictive ability. The energy analysis-based rock drilling method for the prediction of UCS is proposed. This method realized the quick and convenient in situ test of rock UCS.

• The Korean Journal of Ecology
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• 제14권4호
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• pp.371-377
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• 1991

Some morphological characteristics were investigated on the leaves of quercus aliena, hypostomatous species, and lespedeza cyrtobotrya, amphistomatous species, that appeared dominantly on the rock faces in mt.pukhan, mt surak and mt. pulam near seoul. These characteristics were compared with those of normal sites rock faces. All two species growing on the rock faces had thickened leaves with well developed upper epidermis and palisade tissue. Quercus aliena growing on the rock faces showed the leaves with double layer of palisade cells and more regularly arranged spongy parenchyma cells to the lower epidermis. In the case of lespedeza cyrtobotrya, narrower and more lengthened palisade cells and smaller air gaps between the sponge parenchyma cells were observed on the rock faces than those growing in the normal sites. The stomater frequency of the lower epidermis of the tree leaves growing on the rock faces is higher thanthose of normal sites. However, the mean total stomata number of the tree leaves growing on the rock faces are fewer. Most of the morphological characteristics investigated indicate that the plants on the rock faces havesmaller coefficient of variation than those of the normal sites.

• Geomechanics and Engineering
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• 제1권2호
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• pp.143-154
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• 2009

Many factors influence occurrences of rock burst in coal mines, such as mining methods, control methods of the coal roof, lithological characteristics of the roof and floor, tectonic stress, groundwater and so on. Among those factors, lithological characteristics in the roof are the intrinsic controlling factors that affect rock burst during coal mining. Tangshan colliery is one of the coal mines that have suffered seriously from rock bursts in China. In this paper, based on the investigating the lithological characteristics of coal roofs and occurrence of rock bursts in Tangshan colliery, a numerical method is used to study the influence of roof lithological characteristics on rock burst potential. The results show that the lithological characteristics in the roof have an important impact on the distributions of stresses and elastic strain energy in coal seams and their surrounding rocks. Occurrences of rock bursts in this colliery have a close correlation with the thick-bedded, medium- to fine-grained sandstones in the roof. Such strata can easily cause severe stress concentration and accumulate enough energy to trigger rock bursts in the working face during mining operations.

• 지질공학
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• 제32권1호
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• pp.85-99
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• 2022

Rock discontinuities, as weak interfaces in rock, control mechanical properties of rock mass. Presence of discontinuities complicates the engineering properties of rock, which is the root of anisotropy and heterogeneity that have nonnegligible influences on the rock engineering. Morphological characteristics of discontinuities in natural rock are an important factor influencing the mechanical properties, particularly roughness, of discontinuities. Therefore, the accurate measurement and characterization of morphologies of discontinuities are preconditions for studying mechanical properties of discontinuities. Taking discontinuities in red sandstone as research objects, the research obtained three-dimensional (3D) morphologies of discontinuities in natural rock by carrying out 3D morphological scanning tests. The waviness and roughness were separated from 3D morphologies of rock discontinuities through wavelet transform. In addition, the calculation method for the overall slope root mean square (RMS) as well as slope RMSs of waviness and roughness of 3D morphologies of discontinuities considering the shear direction was proposed. The research finally determined an evaluation method for 3D morphologies of discontinuities by quantitatively characterizing 3D morphologies with the mean value of the three slope RMSs.

• 터널과지하공간
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• 제1권
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• pp.1-5
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• 1991