• Tunnel and Underground Space
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• v.7 no.1
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• pp.65-74
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• 1997

Underground structures show different behaviors depending upon the space and the mechanical characteristics of discontinuities, such as joints, beddings, faults and shear zone. Desingning the rock structeres without considering the significance of these discontinuities can lead to false conclusions. This paper includes study on the following topics; the numerical analysis of continuous rock and discontinuous rock around a tunnel, the influences on shotcrete moment and rock-bolt axial force of tunnel due to different joint orientation and stiffness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.363-368
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• 1995

A general method of solving inverse kinematics of three-joint manipulator composed of revolute joints or prismatic joints or combinations of those joints is presented in this study. In completing real-time control, it is very important to obtain the closed form solutions of inverse kinematics rather than iterative numerical solutions, because iterative numerical solutions are generally much slower than the corresponding closed form solutions. If it is possible to obtain the inverse kinematic solutions for general cases of considering twist anlges and offsets, the manipulator work space can be designed and enlarged more effciently for specific task. Moreover, in idustrial manipulators, the effect of main three joints is larger than that of the other three joints related to orientation in the view of work space. Therfore the solutions of manin three-joint are considered. Even The inverse kinematic equations are complicatedly coupled, the systematical solving process by using symbolic calculation is presented.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.492-496
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• 1988

Usually the first three joint variables (major link) and the next three joint variables (minor link) are used to determine the position and the orientation, respectively, of 6 degrees-of-freedom robot manipulators. In this paper, the Jacobians of 20 major links and 6 minor links are calculated to find the positional maneuverability matrices and orientational maneuverability matrices. Then the kinematic characteristics of the major and minor links are examined. Also we gave the measures of maneuverability and the controllability of the links for the figure of merits of robot manipulator design.

• Tunnel and Underground Space
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• v.5 no.1
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• pp.1-10
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• 1995

The behavior of a jointed rock mass depends mainly on the geometrical and mechanical properties of joints. The failure mode of a rock mass and kinematics of rock blocks are governed by the orientation, spacing, and persistence of joints. The mechanical properties such as dilation angle, shear strength, maximum closure, strength of asperities and friction coeffiient play important roles on the stability and deformation of the rock mass. The normal and shear behaviour of a joint are coupled due to dilation, and the joint deformation depends also on the boundary conditions such as stiffness conditons. In this paper, the joint constitutive law including the dilatant behaviour of a joint is numerically modelled using the edge-to-edge contact logic in distinct element method. Also, presented is the method to quantify the input parameters used in the joint law. The results from uniaxial compression and direct shear tests using the numeical model of the single joint were compared to the analytic results from them. The boundary effect on the behaviour of a joint is verified by comparing the results of direct shear test under constant stress boundary condition with those under constant stiffness boundary condition. The numerical model developed is applied to a complex jointed rock mass to examine its performance and to evaluate the effect of joint dilation on tunnel stability.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.97-107
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• 2007

Accurate evaluation of the slope stability by assuming failure block as the entire slope is considered to be apposite for the small scale slope, whereas it is not the case for the large scale slope. Hence, appropriate estimation of a failure block size is required since the safety factor and the joint strength parameters are the function of the failure block size. In this paper, the size of failure block was investigated by generating 3-dimensional rock joint system based on statistical data of joints obtained from research slope, such as joint orientation, spacing and 3-dimensional joint intensity. The result indicates that 33 potential failure blocks exist in research slope, as large as 1.4 meters at least and 38.7 meters at most, and average block height is 15.2 meters. In addition, the data obtained from 3 dimensional joint system were directly applicable to the probability analysis and 2 and 3 dimensional discontinuity analysis.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.87-92
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• 2001

An error analysis is very important for a precision machine to estimate its performances. This study proposes a new parallel device, cubic parallel manipulator. Errors of the proposed cubic parallel manipulator include upper and down universal joint errors, due to the directional changes in the forces in the links, and actuation errors. An error analysis is presented based on an error model formed through the relation between the universal joint errors of the cubic parallel manipulator and the end effector accuracy. The analysis shows that the method can be used in predicting the accuracy of other cubic parallel devices.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.342-350
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• 1998

In this study, fracture network in rock mass was interpreted using borehole wall images obtained by televiewer. The orientation and JRC value of major joint set were evaluated adopting image analysis techniques, of which process were written in macro-program code. As linking JRC to joint stiffness using Barton-Bandis model, fracture network map was produced for application to jointed rock modelling in numerical analysis of underground structure.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.147-152
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• 1999

Distribution of fracture system is an important factor to analyse instability of jointed rock slope. In the most case of rock slopes, joint distribution properties are related to potential, shape, size and locality of slope failure. The purpose of this paper is to present an application of fracture characterization related to rock slope failure. Fracture data used in this study are collected by scanline survey. Two aspects of fracture characterization for rock slope are handled in this study First, In order to determine the potential and shape of slope failure, trace length of joints is considered as the weighting factor about collected orientation data. Second, Relationship between trace length and spacing is analysed to estimate failure location and size. The distribution of fracture system is directly influenced on wedge failure. It is effective to analyse the orientation of fractures by using weighting factors associated with the trace length of fractures rather than to analyse only that of fractures. It gives a conclusion that the wedge failure occurred along the peak of fracture density(or intensity) cycles.

• International Area Studies Review
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• v.13 no.3
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• pp.481-500
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• 2009

This paper investigates the Moderating effect of entrepreneurship on the relationship between market orientation and international performance in Korean Ventures. Literature revealed that an appropriate alignment between firm strategic orientation and market positioning is critical because of its impact on firm performance. The alignment is especially crucial for SMEs as a result of their limited resource base. However, studies have not adequately accounted for the joint effect of entrepreneurship and market orientation on firm performance in different environments as foreign markets. Drawing upon a sample of 217 internationalized Korean Venture Business, it presents evidence related to mainly moderating effects of entrepreneurship on market orientation-international performance. The Key conclusion from the evidence is that market orientation, alone and in conjunction with certain entrepreneurship dimensions, is positively related to firm international performance. More specifically innovativeness and proactiveness have positively moderated the relationship between market orientation and international performance in Korean Ventures.

• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.431-435
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• 2008

Quantitative information of a three dimensional(3D) kinematics of joint is very useful in knee joint surgery, understanding how knee kinematics related to joint injury, impairment, surgical treatment, and rehabilitation. In this paper, an automated 2D/3D image matching technique was developed to estimate the 3D in vivo knee kinematics using dual X-ray images. First, a 3D geometric model of the knee was reconstructed from CT scan data. The 3D in vivo position and orientation of femoral and tibial components of the knee joint could be estimated by minimizing the pixel by pixel difference between the projection images from the developed 3D model and the given X-ray images. The accuracy of the developed technique was validated by an experiment with a cubic phantom. The present 2D/3D image matching technique for the estimation of in vivo joint kinematics could be useful for pre-operative planning as well as post-operative evaluation of knee surgery.