• Journal of the Korean Wood Science and Technology
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• v.23 no.3
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• pp.40-47
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• 1995

This study was carried out to develop a finite element analysis model that considers the semi-rigid characteristics of a wood-dowel joint, which is different from conventional joints that are used in the field of engineering. Wood-dowel joints are classified as semi-rigid joints that possess the following characteristics: (1) they are less stiffer than rigid joints and (2) their stiffness is determined by the dowel's diameter, depth of dowel embedment in the face member and quantity of pin dowels. In this study a finite element model that considers the changes in stiffness according to the above mentioned factors was developed and its suitability was verified by experiments using a wood-dowel joint test specimen made up of particleboards. After comparing the experimental results and the analysis results of the wood-dowel joint which was applied with the proposed finite element model, less than 10% of error was found which is considered to be negligibly small. Hence this shows that this proposed finite element model can be used to predict deformation of wood-dowel joints.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.84-90
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• 1999

The shape of weld nuggest in arc spot welding of 304 stainless steel was found by searching thermal history of a weld joint through a three-dimensional finite element model. The problem consists of one in which the finite element mesh is growing continuously in time in order to accomodate metal transfer in arc spot welding using element rebirth technique. The analysis was performed on the basis of experimental results. The finite element program MARC, along with a few user subroutines, was employed to obtain the numerical results. Temperature-dependent thermal properties, stir effect in weld pool, effect of phase transformation, and the convective and radiative boundary conditions are included in the model. Numerically predicted shape of weld nuggest is compared with the experimentally observed shape.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.1
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• pp.84-91
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• 2017

This paper is proposed to select the optimal finite element type in finite element analysis. Based on the NUREG reports, static analyses were performed using a commercial analysis program, $ABAQUS^{TM}$. In this study, we used a nonlinear kinematic hardening model proposed by Chaboche. The analysis result of solid elements by inputting the same material constants was different from the results of the NUREG report. This is resulted from the difference between shell element and solid element. Therefore, the material constants that have similar result to the experimental result were determined and compared according to element type. In case of using solid element for efficient finite element analysis, we confirmed that the use of C3D8I element type(incompatible mode 8-node linear brick element) leads the accurate result while reducing the analysis time.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.480-488
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• 2012

The aircrafts with high aspect ratio wings made by a composite material have been developed, which enable high energy efficiency and long-term flight by reducing air resistance and structural weight. However, they have difficulties in securing the aeroelastic stability such as the flutter because of their long and flexible wings. The flutter is unstable self-excited-vibration caused by interaction between the structural dynamics and the aerodynamics. It should be verified analytically prior to first flight test that the flutter does not happen in the range of flight mission. Normally, the finite element model is used for the flutter analysis. So it is important to construct the finite element model representing dynamic characteristics similar to those of a real aircraft. Accordingly, in this research, to acquire dynamic characteristics experimentally the modal test of the aircraft with high aspect ratio composite wings was conducted. And then the modal parameters from the finite element analysis(FEA) were compared with those from the modal test. To make analysis results closer to test results, the finite element model was updated by means of the sensitivity analysis on variables and the optimization. Finally, it was proved that the updated finite element model is reliable as compared with the results of the modal test.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.3
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• pp.118-123
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• 1999

This paper describes the finite element procedure including the magnetic hysteresis phenomena. The magnetization-dependent Preisach model is employed to simulate the magnetic hysteresis and applied to each elements. Magnetization is calculated by the Fibonacci search method for the applied field in the implementation of the magnetization-dependent model. This can calculate the magnetization very accurately with small iteration numbers. The magnetic field intensity and the magnetization corresponding to the magnetic flux density obtained by the finite element analysis(FEA) are computed at the same time under the condition that these balues must satisfy the constitutive equation. In order to reduce the total calculation cost, pseudo-permeability is used for the input for the FEA. It is found that the presented method is very useful in combining the hysteresis model with the finite element method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.495-499
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• 2014

In this study, the finite element modeling for the signal cable and pneumatic hose of the industrial robot is developed. The modulus of elasticity of signal cable and pneumatic hose is predicted by deflection test. Finite element model for the signal cable and pneumatic hose is developed by using the modulus of elasticity obtained from the tests. The developed finite element model is estimated through the vibration analysis. This study shows that the developed finite element model can be effectively utilized in the dynamic analysis.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.28-34
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• 2003

In the present study, three-dimensional finite element analysis was performed to investigate the effects of internal wall thinning defect on the failure pressure of elbow in the piping system and to develop the failure pressure evaluation model. From the results of finite element analysis, the failure pressure was derived by employing local stress criteria, and the effects of thinning location, bend radius, and defect geometry on the failure pressure of internally wall thinned elbow were investigated. Also, based on these investigations and previous model developed to estimate the failure pressure of elbow with an external pitting defect, the failure pressure evaluation model to be applicable to the elbow containing an internal thinning defect was proposed and compared with the results of finite element analysis. The failure pressure calculated by the model agreed well with the results of finite element analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1032-1039
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• 2001

In this paper, modal analysis of wind-power generator rotor system was performed by using finite element method. Experimental modal analysis of generator rotor system was performed and the result were compared with analytical ones. Sensitivity method and localized modification method were used to update finite element model. As a result of updating finite element model, errors of natural freguency were reduced within 0.5％ and MAC value was improved near by l. Stability characteristics of wind-power generator rotor-bearing system through harmonic analysis about several external force will be analyzed using finite element model.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• Journal of KSNVE
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• v.9 no.1
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• pp.163-173
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• 1999

Precise and reasonable modelling is necessary and indispensable to the analysis of dynamic characteristics of mechanical structures. Also. the effective prediction of the change of modal properties due to the variation of design parameters is required especially for the application of finite element method to the structural dynamics problems. To meet those necessity and requirement, three model updating algorithms are proposed for finite element methods. Those algorithms are based on sensitivity analysis of the modal data obtained from experimental modal analysis(EMA) and analytical modal analysis(AMA). The adapted sensitivity analysis methods of the algorithms are 1)eigensensitivity(EGNS) method. 2)frequency response function sensitivity(FRFS) method. 3)sensitivity based element-by-element method (SBEEM), Singular value decomposition(SVD) is used for performing eigenanalysis and parameter estimation in the updating process. Those algorithms are applied to finite element of a plate and the updating capability of each algorithm is compared in terms of accuracy. reliability and stability of the updating process. It is shown that the model updating method using frequency response function is superior to the other methods in view of various updating capabilities.