• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.195-201
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• 2006

The wave load and its influence on the response of offshore structure have been well investigated through the statistical approach based on the linear theory. The linear approach has a limitation to apply the extreme condition such as freak wave, which corresponds to extreme value of wave spectrum. The main topic of present study is to develop an efficient numerical method to predict wave load induced by extreme wave. As a numerical method, finite element method based on variational principle is adopted. The frequency-focusing method is applied to generate the extreme wave in the numerical wave tank. The wave load on the bottom mounted vertical cylinder is investigated. The hydroelastic response of the vertical cylinder is also investigated so as to compare the wave loads with the rigid body case in the extreme wave condition.

• Journal of Navigation and Port Research
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• v.31 no.1 s.117
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• pp.21-27
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• 2007

The wave load and its influence on the response of offshore structure have been well investigated through the statistical approach based on the linear theory. The linear approach has a limitation to apply the extreme condition such as extreme wave, which corresponds to extreme value of wave spectrum. The main topic of present study is to develop an efficient numerical method to predict wave load induced by extreme wave. As a numerical method, finite element method based on variational principle is adopted. The frequency-focusing method is applied to generate the extreme wave in the numerical wave tank. The wave load on the bottom mounted vertical cylinder is investigated. The hydroelastic response of the vertical cylinder is also investigated so as to compare the wave loads with the rigid body case in the extreme wave condition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.99-106
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• 2019

A wall-frame structure resists horizontal load by the interaction between the flexural mode of the shear wall and the shear mode of the frame, which implies that the frame deflects only by reverse bending of the columns and girders, and that the columns are axially rigid. However, as the height of frame increases the shear mode of frame changes to flexural mode, which is due to the extension and shortening of the columns. An approximate hand method for estimating horizontal deflection and member forces in high-rise shear wall-frame structures subjected to horizontal loading is presented. The method is developed from the continuous medium theory for coupled walls and expressed in non-dimensional structural parameters. It accounts for bending deformations in all individual members as well as axial deformations in the columns. The deformations calculated from the presented approximate method and matrix analysis by computer program are compared. The presented approximate method is more accurate for the taller structures.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.24-34
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• 2022

This paper investigates the capture of a 12U-sized CubeSat space object using a spider-web structure-based space net. The structural dynamics analysis program ABAQUS is used to simulate the shock-absorbing capability of the space net with a diagonal length of 2.828 m. The space object is modelled as a rigid body, and the space net is modelled using non-linear elastic beam elements. The simulations reveal that the spider-web structure-based space net outperforms the squared space net of the same structural weight in capturing the space object. The numerical simulations are conducted to examine the successful or unsuccessful captures of the space object in various cooperative and non-cooperative motions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.309-316
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• 2022

This study proposes a finite element analysis method that can analyze the vibration of a beam by considering the inertia effect of moving masses in a vertical direction. The proposed method is effective when a precise interaction analysis is not required. The inertial effects of the moving masses are included in the equation of motion, and the interaction forces between the masses and the beam are considered only as external loads. Time domain analyses were performed using Abaqus, a general-purpose finite element analysis software, and an implementation method using multi-point constraints wais presented to link the displacements of the beam element nodes and moving rigid masses. The proposed method was verified by comparing its solution with that obtained using an existing analytical method, and the analysis results for continuous beam vibrations under dynamic gait loadings were used to examine the mass effect of pedestrians.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.233-242
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• 2008

This study presents a non-prismatic beam element for modeling the elastic and inelastic behavior of steel beams, which have the post-Northridge(cover plate) connections in steel moment frames that are subjected to earthquake ground motions. The elastic stiffness matrix for non-prismatric members with increased beam section (IBS) connection is in the closed-form. The plasticity model is of a discrete type and is composed of a series of nonlinear hinges connected by rigid links. The hardening rules can model the inelastic behavior for monotonic and random cyclic loading, and the effects of local buckling. Moreover the determination of yield surfaces, stiffness parameters, and hardening (or softening) rule parameters for IBS beam element were described. Analytical results of the IBS beam element show good correlation with test data and FEM results.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.17-32
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• 2002

The purpose of this study was to find the rational method to analyze golf swing with specific property of club shaft. Three subjects were filmed by two high speed digital cameras with 500 fps. The phase analyzed was downswing of each subject. The three-dimensional coordinates of the anatomical landmarks were obtained with motion analysis system Kwon3d 3.0 version and smoothed by lowpass digital filter with cutoff frequency 6Hz. From these data, kinematic and kinetic variables were calculated using Matlab(ver 5.0) The variables for this study were angular velocity and accelerations, which were calculated and following conclusions have been made : 1) Golf swing time of stiff club is faster than that of regular club. 2) In shoulder joint motion of swing with the stiff club, x-stiff showed mort rapid negative acceleration than that of regular club. 3) In regular club, the velocity of club head would be more effective velocity, which was increasing, than those of other clubs before impact. 4) In wrist joint motion of swing with stiff club, x-stiff club showed faster than regular club in the downswing and impact more rapid negative acceleration.

• 한국해양학회지
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• v.30 no.4
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• pp.355-364
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• 1995

A heavy fluid is injected to a rotating cylindrical container of flat or inclined bottom filled with homogeneous lighter fluid. Continuous flow-in and spreading patterns over the bottom of the container are observed and at the same time upper-layer motions induced by the movement of the heavy fluid are traced by thymol blue solution. Regardless of bottom geometry, the injected denser fluid is deflected toward "western wall" and continuous its path along the boundary with radial spreading which occurs in the bottom boundary layer to make a quite asymmetric flow. When the bottom contains a slope(${\beta}$-plane), increased pressure gradient causes the fluid move faster to produce a stronger Coriolis force. This makes the width of the flow narrower than that of f-plane. But, when the denser flow reaches the southern part of the container, a local-depth of denser fluid increases (much greater than the Ekman-layer depth) such that the spreading velocity along the wall is reduced and the interfacial slope increases to make the upper-layer adjust geographically to have oppositely directed upper-layer motion along the interfacial boundary. The role of the denser fluid in terms of vorticity generation in the upper-layer is such that it produces local topographic effect over the western half of the container and also induces vortex-tube stretching which is especially dominant in the f-plane.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.