• Wind and Structures
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• v.7 no.6
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• pp.359-372
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• 2004

Wind tunnel model studies were carried out to determine the wind load distribution on tributary areas near the gable-end of large, low-rise buildings with high pitch planar and curved roof shapes. Background pressure fluctuations on each tributary area are described by a series of uncorrelated modes given by the eigenvectors of the force covariance matrix. Analysis of eigenvalues shows that the dominant first mode contributes around 40% to the fluctuating pressures, and the eigenvector mode-shape generally follows the mean pressure distribution. The first mode contributes significantly to the fluctuating load effect, when its influence line is similar to the mode-shape. For such cases, the effective static pressure distribution closely follows the mean pressure distribution on the tributary area, and the quasi-static method would provide a good estimate of peak load effects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.385-394
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• 2012

A computer program that can estimate static, dynamic stability and control derivatives using a subsonic-supersonic panel method is developed. The panel method uses subsonic-supersonic source and elementary horse shoe vortex distributions, and their strengths are determined by solving the boundary condition approximated with a thin body assumption. In addition, quasi-steady analysis on the body fixed coordinate system allows the estimation of damping coefficients of aircraft 3 axes. The code is validated by comparing the neutral point, roll and pitch damping of delta wings with published analysis results. Finally, the static, dynamic stability and control derivatives of F-18 are compared with experimental data as well as other numerical results to show the accuracy and the usefulness of the code.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1503-1509
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• 1994

An analysis method is suggested and experimentally studied in order to solve a vibration problem of a flexible structure while it is moving. In this method, substructure synthesis method, modal analysis method and Newmark's integral method were used. Total deformation of a structure was composed of quasistatic component and dynamic component. Rigid body modes were considered in calculation of dynamic component. Combining those two component, deformation behavior and a real structural model of a transfer feeder showed good agreements with computational results.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.13-25
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• 2012

The purpose of this study was to investigate the seismic behavior of hollow circular reinforced concrete bridge columns with confinement steel, and to develop improved seismic design criteria. Three hollow circular columns were tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. The numerical method used gives a realistic prediction of the seismic performance throughout the loading cycles for the several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve current practice in the design and construction of hollow circular reinforced concrete bridge columns.

• The Journal of the Acoustical Society of Korea
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• v.22 no.6
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• pp.512-518
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• 2003

In this paper, resonance durability analysis is performed for the fatigue life assessment considering vibration effect of a vehicle system. In the resonance durability analysis, the frequency response and the dynamic load on frequency domain are used. Multi-body dynamic analysis, finite element analysis, and fatigue life prediction method are applied for the virtual durability assessment. To obtain the frequency response and the dynamic load history, the computer simulations running over typical pothole and Belgian road are carried out by utilizing vehicle dynamic model. The durability estimations on the rear suspension system of the passenger car are performed by using the resonance durability analysis technique and compared with the quasi-static durability analysis. The study shows that the fatigue life considering resonant frequency of vehicle system can be effectively estimated in early design stage.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.156-162
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• 2008

The static aeroelastic analysis of composite hingeless rotor blades in hover was performed using free-wake method. Large deflection beam theory was applied to analyze blade motions as a one-dimension beam. Anisotropic beam theory was applied to perform a cross-sectional analysis for composite rotor blades. Aerodynamic loads were calculated through a three-dimensional aerodynamic model which is based on the unsteady vortex lattice method. The wake geometry in hover was described using a time-marching free-wake method. Numerical results of the steady-state deflections for the composite hingeless rotor blades were presented and compared with those results based on two-dimensional quasi-steady strip theory and prescribed wake method. It was shown that wakes affect the steady-state deflections.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.206-215
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• 1993

The finite element method is applied to analyze the mechanism of metal cutting, especially micro metal cutting. This paper introduces some effects, such as constitutive deformation laws of workpiece material, friction of tool-chip contact interfaces, tool rake angle and also simulate the cutting process, chip formation and geometry, tool-chip contact, reaction force of tool. Under the usual plane strain assumption, quasi-static analysis were performed with variation of tool-chip interface friction coefficients and tool rake angles. In this analysis, cutting speed, cutting depth set to 8m/sec, 0.02mm, respectively. Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction forces on tool. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.

• Journal of the Korea Convergence Society
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• v.8 no.12
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• pp.283-289
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• 2017

In this study, a general program has been developed to calculate the static design factor of a vehicle suspension system. The partial derivatives of Jacobians for constraint equations are calculated using the symbolic technique. In the commercial program, finite difference method is used to calculate the Jacobian matrix of Jacobian. But in this study, it is calculated by using the symbol calculation method to precisely consider it. The calculated Jacobian matrix for the system has proved its accuracy through the solution of the numerical example. A simulation was performed for a double wishbone suspension of a 1/4 vehicle. The result can be used to calculate the static design factor of the suspension, and also add a convergence module that can perform virtual tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.597-602
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• 2006

In this paper, a proper support tuning method is established by identifying the dynamic characteristics of the machine, the floor. and the inertia force. Also, the limitation of a passive isolation is presented. To simplify the dynamic analysis and to establish a proper design method for supporting system, each of the machine and the floor is modeled as a single degree of freedom spring-mass-damper system under careful investigation of the dynamic characteristics of each system and appropriate assumptions. Then, the dynamic behavior of a 2DOF system and the effect of the mass and the damping are investigated. Also, the characteristics of motion profiles are investigated. In addition, a quasi-static analysis on the transmitted force through support is performed and related tests are performed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.553-560
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• 2001

To substantiate the application of LRB(Laminated Rubber Bearing) to the seismic isolation system, it is necessary to develop a seismic analysis method considering the non-linear behavior of LRBs, which may significantly affect the seismic responses. In this paper, seismic analyses and shaking table tests are carried out for a seismically isolated structure using four LRBs. The parameter equations of seismic isolation frequency are obtained from the shaking table tests and the quasi-static tests of LRB itself to investigate the effects of the LRB characteristics in the prediction of maximum peak acceleration responses by analysis. From the comparison of the maximum peak acceleration responses obtained from numerical analyses and experiments, it is verified that the horizontal stiffness variations of LRB should be carefully considered in seismic analysis to obtain more accurate results.