• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1306-1313
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• 2009

Dynamic and static behaviors of a three-dimensional catenary system for a high-speed railway are analyzed by using the finite element method. Considering tensions in the contact wire and the messenger wire, we drive the equations of motion for the catenary system. These equations are for the longitudinal, transverse, vertical and torsional motions. After establishing the weak form, the weak forms are spatially discretized with newly defined two-node beam elements. With the discretized equations, a finite element computer program is developed for the static and dynamic analyses. The static deflections of the catenary system, which are important for good contact between the pantograph and the contact line, are computed when the gravity is applied. On the other hand, we analyze the natural frequencies and the corresponding natural modes of the catenary system. The dynamic responses of the system are also investigated when applying a load to the contact line. For verification of the developed finite element program, vibrations of the catenary system are measured and they are compared to computed time responses.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.146-154
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• 1996

In this work, rapid prototyping and three-dimensional finite element analysis are simultaneously applied to the die design of metal forming processes. Rapid prototyping is a new prototyping technology which produces three-dimensional part models directly from CAD data and has been extensively applied to various manufacturing processes. There are many types of rapid prototyping systems due to their building principles and materials. In this work, Stereolithography Apparatus(SLA), which is the most widely used rapidprototyping system, is introduced to manufacture the die set. For general preparation of STL file, which is the standard input file of rapid prototyping system, mesh data which are used in describing the die surface in finite element analysis are translated so that rapid prototyping and finite element analysis are dffectively connected. A die set for spider forging and a clover punch for deep drawing section are manufactured effciently using SLA prototypes, and metal forming experiments are carried out using them. Comparing the result of experiments with that of analyses, the processes can be predicted and designed successfully.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.11 no.1
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• pp.95-105
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• 2007

A mathematical modeling for the drying process of hygroscopic porous media, such as wood, has been developed in the past decades. The governing equations for wood drying consist of three conservation equations with respect to the three state variables, moisture content, temperature and air density. They are involving simultaneous, highly coupled heat and mass transfer phenomena. In recent, the equations were extended to account for material heterogeneity through the density of the wood and via the density variation of the material process, capillary pressure, absolute permeability, bound water diffusivity and effective thermal conductivity. In this paper, we investigate the drying behavior for the three primary variables of the drying process in terms of control volume finite element method to the heterogeneous transport model on one-dimensional grid.

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.301-313
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• 2009

This paper presents a Finite Element Method (FEM) application to thermal study of natural three layers of human dermal parts of varying properties. This paper carries out investigation of temperature distributions in these layers namely epidermis, dermis and under lying tissue layer. It is assumed that the outer skin is exposed to atmosphere and the loss of heat due to convection, radiation and evaporation of water have also been taken into account. The computations are carried out for one dimensional unsteady state case and the shape functions in dermal parts have been considered to be quadratic. A Finite Element scheme that uses the Crank-Nicolson method is used to solve the problem and the results computed have been exhibited graphically.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.48-55
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• 2010

When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.129-133
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• 2001

A finite element-based, integrated process model is presented for a three dimensional, coupled analysis of the thermo-mechanical behavior of the strip and work roll in the continuous hot strip rolling. The validity of the proposed model is examined through comparison with measurements. The effect of Edge-Heater on the finishing delivery temperatures is examined by using the present model. The models capability of revealing the effect of diverse process parameters is demonstrated through a series of process simulation.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1596-1603
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• 2018

This paper presents the new design and validation process of the linear transverse flux machine of the stelzer machine for hybrid vehicle application. A linear transverse flux machine is a novel electric machine that has higher force density and power than conventional electric machine. The process concentrates on 2-dimensional and 3-dimensional analysis using equivalent magnetic circuit method considering leakage elements and it is verified by finite element analysis. Besides the force characteristics of all axis of each direction are analyzed. The study is considered by dividing the transverse flux electric excited type and the transverse flux permanent magnet excited type. Additionally three-dimensional analysis in this machine is accomplished due to asymmetric structure with another three axes. Finally, it suggests the new design and validation process of linear transverse flux machine for stelzer machine.

• Ocean Systems Engineering
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• v.1 no.4
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• pp.317-336
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• 2011

A time domain finite element based method is employed to analyze wave radiation by multiple cylinders. The nonlinear free surface and body surface boundary conditions are satisfied based on the perturbation method up to the second order. The first- and second-order velocity potential problems at each time step are solved through a finite element method (FEM). The matrix equation of the FEM is solved through an iteration and the initial solution is obtained from the result at the previous time step. The three-dimensional (3D) mesh required is generated based on a two-dimensional (2D) hybrid mesh on a horizontal plane and its extension in the vertical direction. The hybrid mesh is generated by combining an unstructured grid away from cylinders and two structured grids near the cylinder and the artificial boundary, respectively. The fluid velocity on the free surface and the cylinder surface are calculated by using a differential method. Results for various configurations including two-cylinder and four-cylinder cases are provided to show the mutual influence due to cylinders on the first and second waves and forces.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1213-1222
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• 1999

A finite element method is developed for calculating the temperature and enthalpy distribution and accordingly the solid, liquid and mushy zone in a three-dimensional body subjected to any heat boundary conditions. The method concurrently consider both temperature and enthalpy for consideration of the latent heat effect, differently from other methods of using a special energy balance equation for solving a mushy zone. The developed brick element has eight nodes with one degree of freedom at each node. The numerical method and procedure are verified using the results of one and two dimensional analytic solutions and by other researchers. It is shown that the present method presents a consistent and stable results in either abrupt or ranged phase change problems. Moreover, the numerical results by the present method are hardly effected by the calculation time steps which otherwise are difficult to determine in most phase change problems. Finally, as a three-dimensional application, a T-shaped body of a phase change is presented and the temperature and enthalpy variation along the time are solved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.877-881
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• 2002

Much research efforts have been made on the equal channel angular pressing(ECAP) which produces ultra-fine grains. In this paper the ECAP processes with Zr-702 alloy at elevated temperature and at room temperature are considered. Both two-dimensional and three-dimensional finite element analyses have been employed to investigate the deformation behaviors of specimen during ECAP process.