• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.63-70
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• 2000

The quantitative analyses and the mechanical interpretation of discontinuity planes are the most important factor for the study of strength and deformation properties of rock masses containing discontinuity planes. However, the relationship between the factors investigated in the field and the actual mechanical properties of discontinuity planes is not fully understood. The main purpose of this study is to investigate the effects of density, length, and spacing of joints on elastic modulus of rock masses as these values vary. A new parameter which has a direct relation with the elastic modulus of discontinuity planes is also preposed in this study. The combination of finite element methods and homogenization methods has been used for the numerical analyses of a uintcell with discontinuity planes, which is generated using random-number generation methods. The elastic modulus of the discontinuity plane is found from the numerical analyses. The final results propose not only the relation between the investigation parameters of discontinuity planes and the elastic modulus of rock masses but also a new parameter, an effect area ratio having a linear relation with the elastic modulus of rock masses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.102-108
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• 2017

The phenomenon of technological discontinuity which occurs during technological diffusion and substitution between incumbents and new technology is important to understand the behavior of technology diffusion and substitution of single and multiple technologies. Our research defined the concept of technological discontinuity and developed a model capable of measuring the region of technological discontinuity. Based on a literature review and a model development, we proposed a definition and a model regarding technological discontinuity.The accuracy of the model is verified by applying it on a semiconductor industry case. The technological discontinuity is defined as the region in which both the incumbent and new technology co-exist and the performance of the incumbent technology is better than that of the new technology. In addition, we can model the technological discontinuity using discontinuous time and discontinuous performance. This research will be very useful to understand not only technological discontinuity but also technology diffusion or substitution.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.106-113
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• 2019

When elemental images are remapped to solve the depth conversion in integral imaging, the integrated image is inevitably accompanied by discontinuity. This paper analyzes the discontinuity factor caused by elemental-image remapping, to validate the reduction of the discontinuity through converging pick-up and reconstruction of the three-dimensional image in real and virtual modes simultaneously. The validity of the proposed method is quantitatively verified when compared with the conventional parallel pick-up.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.123-131
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• 2009

Large scale model tests and numerical analyses were performed in order to investigate the stress distribution on the base of pillar during two-arch tunnel excavation in the regularly jointed rocks. It was observed that the stress was irregularly distributed on pillar and the angle of discontinuities seriously influenced on the stress distribution on the pillar base in the discontinuous rock mass. In the numerical analyses results, It was shown that the stress level of pillar was greatly changed depending on the excavation sequences of two-arch tunnel. It was also observed that stress distributed eccentrically at the pillar as well as at the base of pillar. It is necessary to consider this point for the design of two-arch tunnel.

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.65-73
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• 2009

Large scale model tests and numerical analyses are performed to investigate the stress distribution of pillar due to surface loading nearby two-arch tunnel which is constructed in the regularly jointed rocks. It is observed that the influence of discontinuities on the stress distribution in the discontinuous rock mass and the underground stresses induced by surface loading are greater than those of linear elastic theory. Especially, lines of equal stresses are developed to the direction of inclination according to the inclined grade. In cases of discontinuities imbedded in parallel with or vertical to the ground, the pressure bulbs are formed symmetrically, however, the inclined ones result in stress distribution in parallel with and vertical to the planes of discontinuities. Results indicated that stress distribution is seriously affected by the angle of discontinuity. When stresses propagating to the pillar need to be estimated, relative location of surface loading, grade of discontinuous plane, and location of two-arch tunnel should be carefully considered.

• Proceedings of the KSEG Conference
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• 2000.04a
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• pp.165-173
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• 2000

• Journal of IKEEE
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• v.6 no.1 s.10
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• pp.94-101
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• 2002

In this paper, we propose a motion estimation algorithm for the discontinuity blocks. The algorithm uses sub-SAD value (i.e. the sum of absolute difference for a quarter of a block) to identify the discontinuity region, and produces additional motion vectors for these sub-blocks if necessary. We show with experimental results that, in comparison with some conventional motion estimation algorithms, the proposed algorithm achieves quality enhancement for the sequences with discontinuity blocks, and also shows the same computational quantity as to normal algorithms for sequences with less discontinuity.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.1-10
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• 2006

Rock masses in nature include various rock discontinuities such as faults, joints, bedding planes, fractures, cracks, schistosities, and cleavages. The behavior of rock structures, therefore, is mainly controlled by various rock discontinuities. In many tunnels, enormous cost and time are consumed to cope with the failing or sliding of rock blocks, which cannot be predicted because of the complexity of rock discontinuities. It is difficult to estimate the properties of rock masses before the rock excavation. The observational design and construction method of tunnels in rock masses is becoming important recently. In this paper, a new observational design and construction method for rock block evaluation of tunnels in discontinuous rock masses is proposed, and then applied to the tunnel based on actual rock discontinuity information observed in the field. It is possible to detect key blocks all along the tunnel exactly by using the numerical analysis program developed far the new observational design and construction method. This computer simulation method with user-friendly interfaces can calculate not only the stability of rock blocks but also the design of supplementary supports. The effectiveness of the proposed observational design and construction method has been verified by the confirmation of key block during the enlargement excavation.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.257-268
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• 2005

In situ rock mass is generally heterogeneous and discontinuous, with varying degrees of strength along the planes of weakness. The planes of weakness such as joints, faults, cracks and bedding planes, control the strength and deformation characteristics of the rock mass. Subsequently, the stability of underground opening depends upon the spatial distribution of discontinuities and their mechanical properties in relation with geometrical shape of openins as well as the mechanical properties of intact rock materials. Understanding the behaviour of a discontinuous rock mass remains a key issue for improving excavation design in hiかy stressed environments. Although recent advances in rock mechanics have provided guidelines for the design of underground opening in isotropic rock mass, prediction and control of deformation in discontinuous rock masses are still unclear. In this study, parametric study was performed to investigate the plastic zone size, stress distribution and deformation behavior around underground opening in a discontinuous rock mass using a continuum joint model. The solutions were obtained by an elasto-plastic finite difference analysis, employing the Mohr-Coulomb failure criteria. Non-associated flow rule and perfectly plastic material behavior are also assumed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.459-462
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• 1996