• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.347-352
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• 2012

This paper presents a robotic foot mechanism based on truss structure for walking robots and analyzes its effectiveness for compliant walking. The specified foot mechanism has been modeled by observing the structure and behavior of human foot. The frame of bone used in the human foot is considered as a truss, and the ligaments of the human foot are represented as a simple stiffness element. So such a robotic foot has an advantage to moderate the impact of foot when a walking robot takes a step. As a result, it is practically expected that the proposed robotic foot mechanism can contribute to reduce the physical fatigue of walking robots.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.33-47
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• 1992

A study for the material and geometric nonlinear analysis of segmentally erected cable-supported prestressed concrete plane frames including the time-dependent effects due to load history, creep, shrinkage, aging of concrete, and relaxation of prestressing steel and cable is presented. Updated Lagrangian formulation is used to account for the nonlinear behavior of the structure. For the time-dependent analysis. the time domain is divided into a discrete number of intervals, and a step-forward integration is performed as the solution progresses in the time domain. At each time step. a nonlinear finite element analysis is performed in the space domain. Segmental erection methods are implemented by providing the capability to change the configuration of the structure at any time step of the solution. The computer program CFRAME is developed and a series of numerical examples are presented to study the validity of the program.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.17-26
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• 1990

A solution strategy for geometric non-linear analysis for the plane frame structures subjected to conservative and non-conservative forces is presented. By making efficient combination of the load incremental method and the displacement incremental method, this strategy can find postbuckling configuration such as snap-through and turning-back phenomena which cannot be easily found by the conventional load and displacement incrementation scheme. In the case of the analysis of the framed structure subjected to circulatory non-conservative forces, the total tangent stiffness matrix becomes unsymmetric and when calculating the incremental load and unbalanced load vector components, the direction change of the non-conservative forces is considered. Several example problems to demonstrate the feasibility of the present strategy, over ranges of deformation that are well beyond those likly to occur in practical framed structures, are given and discussed.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.413-421
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• 2012

The purpose of this study is to evaluate the structural dynamic behavior under hybrid control system. The hybrid test is to consider the interaction between the numerical and physical models. In this paper, single degree of freedom hybrid test was performed with one-bay, two-story steel frame structure. One column at the first floor was selected as a physical substructure and one actuator was used for applying the displacement load in horizontal direction. El Centro as earthquake waves was inputted and OpenSees was employed as the numerical analysis program for the hybrid real-time simulation. As a result, the total time of the hybrid test was about 9.6% of actual measured seismic period. The experimental results agreed well with the numerical one in terms of the maximum displacement. In nonlinear analysis, however, material nonlinearity made a difference of residual strain. Therefore, this hybrid dynamic test can be used to predict the structural dynamic performance more effectively than shaking table test, because of the spatial and economic limitations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.61-68
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• 1993

A computer program for free vibration analysis of plane framed structures has been developed by object oriented programming technique using C" language. The object oriented programming concepts such as object, class, method and inheritance are represented. The static and free vibration analyses for framed structures were satisfactorily performed by this program which consists of TOP, VECTOR, MATRIX, STRU, GUI and other classes. Numerical test shows the validity and capability of the present study which can be expandable to develop a general purpose object oriented finite element analysis program of structures ,res ,

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.201-207
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• 1998

In this study, a geometric nonlinear analysis formulation for spatial frames is developed using the 3D stability functions. For the formulation, the relationships of local and global coordinate systems in force, deformation, and the initial and current configurations of a frame are derived. The force-deformation relationship in global coordinate system is derived as well. The developed formulation is verified in each derivation by reducing the derived equations into 2D equations. The gradual plastification of connections and critical sections can be implemented effectively to this formulation for the complete second order inelastic advanced analysis of spatial frames.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.1-12
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• 1993

Tangent stiffness matrices are derived for the torsional and lateral stability analysis of the space beams and framed structures with the symmetric thin-walled section by using the principle of virtual displacement. In the cases of restrained torsion and unrestrained torsion, the elastic and geometric stiffness matrices are evaluated by using the Hermitian polynomials which represent the displacement field of the beam element in simple flexure. Numerical examples illustrate the accuracy and convergence characteristics of the derived formulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.2
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• pp.111-120
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• 1986

Steel frame structures are widely used in construction because of their efficient strength and rigidity and considered proper cases for design and analysis using concept of plastic behavior. The purpose of plastic analysis is to determine the collapse load of a structure when the plastic moments of its members are given, and optimal plastic design is to compute the plastic moments of the members that minimize total structural weight. In this paper, the plastic analysis and optimal design are performed by using the static approach and solved by the simplex method. From the result of the analysis the solutions by this study show more efficiency in calculations. Also, the structural weight solved by the simplex method in case of two story frame is proved more economical than the one using the elastic design around 24%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.93-103
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• 1994

Two beam/column elements are developed in order to analyze the geometric nonlinear plane irames including the effects of internal hinge and transverse shear deformation. In the case of the first element (finite segment method), tangent stiffness matrix is derived by directly integrating the equilibrium equations whereas in the case of the second element (finite element method) elastic and goemetric stiffness matrices are calculated by using the hermitian polynomials including the effects of internal hinge and shear deformation as the shape function. Numerical results are presented for the selected test problems which demonstrate that both elements represent reliable and highly accurate tools.

• The Korean Journal of Quaternary Research
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• v.16 no.2
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• pp.23-31
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• 2002

The mammalian fossil remains of the Quaternary have been the crucial subjects for the archaeologist since long time. Because these materials have been used as a guide to environment and they help us to reconstruct a picture of past human subsistence concerning the hunting, dismembering and bone tools. The mammalians have distinctive characteristics and biotopes in order to adapt to environment change and modify even forms and number of bones. In this paper, we examine bone structures and numbers of several mammalians discovered in Paleolithic site during the Quaternary. We hope that this work could be attribute to more information about the relationship between Paleolithic men and the mammalians.