• Transactions of Materials Processing
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• v.10 no.3
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• pp.246-246
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• 2001

The conventional and new forming processes of a steel shell body are analyzed by the rigid-plastic finite element method. The conventional process contains five forming stages such as bending, drawing, ironing, heading and sizing, which was designed by a forming equipment expert. The results of simulation of the conventional forming process are summarized in terms of deformation patterns and load-stroke relationships for each forming operation. Based on the simulation results of the current five-stage, the shell body forming Process including backward extrusion is designed for improving the conventional process sequence. Forming loads of the proposed process are within the limit value, which is proposed by experts and the proposed process is found to be proper for manufacturing steel shell body.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.245-252
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• 2001

The conventional and new forming processes of a steel shell body are analyzed by the rigid-plastic finite element method. The conventional process contains five forming stages such as bending, drawing, ironing, heading and sizing, which was designed by a forming equipment expert. The results of simulation of the conventional forming process are summarized in terms of deformation patterns and load-stroke relationships for each forming operation. Based on the simulation results of the current five-stage, the shell body forming Process including backward extrusion is designed for improving the conventional process sequence. Forming loads of the proposed process are within the limit value, which is proposed by experts and the proposed process is found to be proper for manufacturing steel shell body.

• Steel and Composite Structures
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• v.7 no.3
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• pp.253-262
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• 2007

A methodology to design symmetrically laminated fibre-reinforced structures under transverse loads for minimum weight, with manufacturing uncertainty in the ply angle, is described. The ply angle and the ply thickness are the design variables, and the Tsai-Wu failure criteria is the design constraint implemented. It is assumed that the probability of any tolerance value occurring within the tolerance band, compared with any other, is equal, and thus the approach is a worst-case scenario approach. The finite element method, based on Mindlin plate and shell theory, is implemented, and thus effects like bending-twisting coupling are accounted for. The Golden Section method is used as the search algorithm, but the methodology is flexible enough to allow any appropriate finite element formulation, search algorithm and failure criterion to be substituted. In order to demonstrate the procedure, laminated plates with varying aspect ratios and boundary conditions are optimally designed and compared.

• Fire Science and Engineering
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• v.16 no.3
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• pp.56-60
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• 2002

Recently, with the growth of software for electro-thermal analysis, it has been studied the precise analysis and investigation of cause for the electrical fire using computer simulation on the basis of theory for electro-thermal analysis. But it is very lacking for the precise analysis and investigation of cause for the electrical fire. In this paper, we have simulated the thermal analysis for electrical wire according to the value of current in a overload and a short with the electrical wire of the L's company product(600 V VVF) using the electro-thermal finite element method(Flux2D).

• Fire Science and Engineering
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• v.16 no.4
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• pp.72-76
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• 2002

Nowaday, with the growth of software for electro-thermal analysis, it has been studied the precise analysis and investigation of cause for the electrical fire using computer simulation on the basis of theory for electro-thermal analysis. But it is very lacking for the precise analysis and investigation of cause for the electrical fire. In this paper, we have simulated the thermal analysis for electrical wire according to the value of current and deteriorating time in a overload and a short with the electrical wire of the L's company product(600 V VVF : Three core) using the elec-tro-thermal finite element method(Flux2D).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.73-80
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• 2006

In order to examine the validity of an asymptotic solution for nonlinear interaction in asymmetric vibration modes of a perfect circular plate, we obtain the numerical solution. The motion of the plate is governed by nonlinear partial differential equation. The initial and boundary value problem is solved by using the finite difference method. The numerical solution is compared with the asymptotic solution. It is found that traveling waves relating clockwise and counterclockwise as well as standing wave are depicted by the numerical solution.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.285-291
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• 2015

In this paper, a composite material analysis program based on the finite element method(FEM) is used. The purpose of this study was to verify whether the composite material analysis program which developed as part of a project of development of softwares and educational contents for structural vibration and composite material analysis that can calculate how similar the macroscopic mechanical behavior of the composite materials actually. Because composite materials are generally anisotropic, analysis of composite laminate is used for the constitutive equations of orthotropic material. For convenience, the unit is ommited in all calculations. To verify the accuracy of the finite element method based program, the deflection and stress distribution of the simply supported composite material laminated plate subjected to a uniform load distribution is compared with exact solution. Size and properties of the composite material laminate used for analysis are fixed variables, and by changing the number of elements and the total thickness of the laminate is compared with the exact solution to the resulting value, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.31-38
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• 1992

In this paper, numerical analysis package using Time-Domain Finite Difference (TDFD) method is developed to solve the initial value problem of Maxwell's equation and applied to several microstrip structures. TDFD allows us to show graphically the evolution of the crosswalk between microstrip lines. Moreover, we can obtain transmission line parameters and scattering parameters through Fourier transform of TDFD results in easy and efficient ways. TDFD is successfully applied to :1) wide band electromagnetic wave propagation along the single microstrip line, 2) crosswalk analysis between two microstrip lines, and 3) three metal line side-coupled filter. Our results show much better agreement with other theoretical experimental results reported in the literature. Thus we expect that TDFD is very useful to designing MMIC(Monolithic Microwave Integrated Circuit).

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.23-29
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• 2002

The electronic properties of Carbon Nanotube(CNT) are currently the focus of considerable interest. In this paper, the electronic properties of finite length effect in CNT for the carbon nano-scale device is presented. To Calculate the electronic properties of CNT, Empirical potential method (the extended Brenner potential for C-Si-H) for carbon and Tight Binding molecular dynamic (TBMD) simulation are used. As a result of study, we have known that the value of the band gap decreases with increasing the length of the tube. The energy band gap of (6,6) armchair CNT have the ranges between 0.3 eV and 2.5 eV. Also, our results are in agreements with the result of the other computational techniques.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.21 no.4
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• pp.225-244
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• 2017

The natural convective nanofluid flow and heat transfer inside a square enclosure with a center heater in the presence of magnetic field has been studied numerically. The vertical walls of the enclosure are cold and the top wall is adiabatic while the bottom wall is considered with constant heat source. The governing differential equations are solved by using a finite volume method based on SIMPLE algorithm. The parametric study is performed to analyze the effect of different lengths of center heater, Hartmann numbers and Rayleigh numbers. The heater effectiveness and temperature distribution are examined. The effect of all pertinent parameters on streamlines, isotherms, velocity profiles and average Nusselt numbers are presented. It is found that heat transfer increases with the increase of heater length, whereas it decreases with the increase of magnetic field effect. Furthermore, it is found that the value of Nusselt number depends strongly upon the Hartmann number for the increasing values of Rayleigh number.