• Journal of Welding and Joining
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• v.14 no.2
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• pp.71-78
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• 1996

In order to rpovide proper SMT design criteria in a systematic way, a mathematical formulation has been developed to predict the configuration of the solder fillet formed between the gullwing type lead and rectangular pad. Effects of SMT design parameters such as the solder volume and pad dimension on the solder profile are investigated using the FEM that calculates the 3D configuration by minimizing the energy due to surface tension and gravity in the equilibrium state. Design criteria of QFP and SOP are illustrated by plotting the acceptable range of the solder volume with respect to the length and width ratios of the pad and lead. The results show that the acceptable design range increases with increase in the pad length and width. The pad length has more significant effects on design criteria compared with the pad width, and Bond number can be utilized to predict the joint quality.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.625-634
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• 1997

Reinforced concrete (RC) interior beam-column joints with high-strength materials: concrete compressive strength of 100 MPa and the yield strength of longitudinal bars of 685 MPa, were analyzed using three-dimensional (3-D) nonlinear finite element method (FEM). Specimen OKJ3 of joint shear failure type was a plane interior joint, and Specimen 12 of beam flexural failure type was a 3-D interior joint with transverse beams. Though the analytical initial stiffness was higher than experimental one, the analytical results gave a good agreement with the test results on the maximum story shear forces, the failure mode.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.197-203
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• 2003

Accurate stress intensity factor analyses and crack growth rate of surface -cracked components in inhomogeneous materials are needed fur reliable prediction of their fatigue life and fracture strengths. This paper describes an automated stress intensity factor analysis of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor fur subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks. Also, this system is applied to analyze cladding effect of surface cracks in inhomogeneous materials.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.25.2-38
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• 1995

the Effect of steel pipe reinforced multi-step grouting(SPRG) technique to inrove the ground far ahead of the excavation face was investigated by means of numerical analysis. It was found taht the nonlinear 3-D FEM program performed well to evaluate the usefulness of the SPRG technique in soft ground tunnelling, and about 20% of settlement control in this particular case possible. Therefore in urban subway tunnel construction, the New Austirial Tunnelling Method can be satisfactorily applied even in poor ground conditon with aid of the SPRG technique.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1007-1009
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• 1993

In this paper, The hybrid method in order to reduce the unknown varible for 3D eddy current calculation is proposed. we adopt the current vector potential(T) and the magnetic scalar potential($\Omega$) as field variable, and adopt image charge method for symetric boundary condition in BEM. We apply the hybrid method to electromagnet for levitation system and analyze the charateristics of eddy current airgap flux distribution, attractive and magnetic drag force according to velocity.

• Journal of the Korean Magnetics Society
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• v.21 no.3
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• pp.99-103
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• 2011

In this study, we have performed systematical FEM analysis for design of open-ended 3-layer magnetic shield. For the simulation to calculated shielding factors, the relative permeability was varied in the range of $2{\times}10^3\sim1{\times}10^5$, and the length of the magnetic cylinders and length difference between layers were changed. We found that the shielding factor of -60 dB were obtained with the relative permeability of over 20000 and the lengths of magnetic layers of 40 cm, 45 cm and 50 cm, and the uniform magnetic field could be obtained in the range of $10cm{\times}10cm-\phi$.

• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.53-56
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• 2016

In this study, experiments and finite element method analysis were used to determine the autofrettage pressure that is optimal and then maximizes the cycling life of Type3 composite cylinders used in self-contained breathing apparatus. For both approaches, the cylinders were pressurized at 100, 110, ${\ldots}$, 290 % of the test pressure, respectively. The stresses were computed by the FEM analysis; while the strains of cylinders were recorded and the failure modes were monitored during the cycling test. As a result, from the good agreements between the simulations and experiments, it was concluded that at least 70 % of the test pressure should be applied as the autofrettage pressure in order to takes visible effect on the cycling life, and 160 % of the test pressure induces the maximum cycling life and the desired failure mode.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.52-58
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• 2007

This study shows a numerical method to predict automobile type air conditioner tube connector in the forming process. The simulation approach with 3-D FEM program(ABAQUS) for forming process, forming process simulation is in good agrement with it in tendency. Finally, we compared the forming result with simulation. The result of research showed thai forming process technology is promising to produce automobile type air conditioner tube connector.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.104-109
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• 2006

In this study, the equivalent plate model is developed using a finite element method(FEM) based on the first order shear deformation theory(FSDT). The substructure synthesis method is used to consider the control surface. For the verification of the equivalent model, the results of free vibration analysis are compared with the ones of 3D wing structure modeled by using the MSC/NASTRAN.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.152-157
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• 2003

A typical die-set for enclosed-die forging of half axle gears in double action hydraulic press is presented, the important factors those influence on precision forming of half axle gears are analyzed, warm forming process of half axle gears is simulated by FEM software $DEFORM\_3D$. The results show, that proper die structure and dimension, suitable web thickness and position can improve material filling, ensure full filling of tooth cavity.