• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.5
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• pp.246-252
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• 2002

Two-dimensional steady state simulations of planar type radio frequency inductively coupled plasma (RFICP) have been performed. The characteristics of RFICP were investigated in terms of power transfer efficiency, equivalent circuit analysis, spatial distribution of plasma density and electron temperature. Plasma density and electron temperature were determined from the equations of ambipolar diffusion and energy conservation. Joule heating, ionization, excitation and elastic collision loss were included as the source terms of the electron energy equation. The electromagnetic field was calculated from the vector potential formulation of ampere's law. The peak electron temperature decreases from about 4eV to 2eV as pressure increases from 5 mTorr to 100 mTorr. The peak density increases with increasing pressure. Electron temperatures at the center of the chamber are almost independent of input power and electron densities linearly increase with power level. The results agree well with theoretical analysis and experimental results. A single turn, edge feeding antenna configuration shows better density uniformity than a four-turn antenna system at relatively low pressure conditions. The thickness of the dielectric window should be minimized to reduce power loss. The equivalent resistance of the system increases with both power and pressure, which reflects the improvement of power transfer efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1499-1507
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• 2003

Physical importance of cutting temperatures has long been recognized. Cutting temperatures have strongly influenced both the tool life and the metallurgical state of machined surfaces. Temperatures in drilling processes are particularly important, because chips remain in contact with the tool for a relatively long time in a hole. Tool temperatures tend to be higher in drilling processes than in other in machining processes. This paper concerns with modeling of thermal behaviors in drilling processes as well as estimation of the cutting temperature distribution based on remote temperature measurements. One- and two-dimensional estimation problems are proposed to analyze drilling temperatures. The proposed thermal models are compared with solutions of finite element methods. Observer algorithms are developed to solve inverse heat conduction problems. In order to apply the estimation of cutting temperatures, approximation methods are proposed by using the solution of the finite element method. In two-dimensional analysis, a moving heat source according to feedrate of the drilling process is regarded as a fixed heat source with respect to the drilling location. Simulation results confirm the application of the proposed methods.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.574-576
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• 2001

This paper deals with High Temperature Superconducting (HTS) Motor, which have two characteristics: the HTS magnet with iron plates as field coil, and the solid nitrogen $(SN_2)$ as a cryogen. The HTS magnet has iron plates to achieve the maximum current-carrying capacity and the simple shape that can easily be wound and jointed. The HTS magnet with iron plates, magnet optimized current distribution, and initial magnet are presented through 3 Dimensional Finite Element Analysis (3D FEA), manufacturing and testing these magnets. And, it is employed $SN_2$ for keep the operating temperature of HTS synchronous motor. To make the liquid nitrogen $(LN_2)$ of $SN_2$, Gas helium (GHe) passes into the heat exchanger and cools its own temperature. Two types of heat exchangers are designed and manufactured to make the $SN_2$, and each of the temperature characteristics is compared.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.377-383
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• 2012

The temperature distribution of an asymmetric trapezoidal fin with various upper lateral surface slopes is investigated by using the two-dimensional analytic method. For this asymmetric fin, convection from the inner fluid to the inner wall, conduction from the inner wall to the fin base and conduction through the fin base are considered simultaneously. The temperature profile with the variation of dimensionless fin length and height coordinates is shown. Also, the temperature variation at the bottom tip of the fin is presented as a function of the fin shape factor. Heat losses through the fin base and from each side are compared for variations in fin length. One of the results shows that temperature at the fin bottom tip decreases linearly as the fin shape factor increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.923-930
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• 2002

Cooling characteristics of a parallel channel with protruding heat sources using convection and conduction heat transfer are studied numerically. A two-dimensional model has been developed for numerical prediction of transient, compressible, viscous, laminar flow, and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve the problem. The assembly consists of two channels formed by two covers and one printed circuit board which has three uniform heat source blocks. Six different cooling methods are considered to find out the most efficient cooling method in a given geometry and heat sources. The velocity and temperature fields of cooling medium, the temperature distribution along the block surface, and the maximum temperature in each block are obtained. The results are compared to examine the cooling characteristics of the different cooling methods.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.46-55
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• 2004

Thermal characteristics of the various cooling methods in electronic equipment are studied numerically. A common chip cooling system is modeled as a parallel channel with protruding heat sources. A two-dimensional model has been developed for the numerical analysis of compressible. viscous. laminar flow. and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The assembly consists of two channels formed by two covers and one printed circuit board that is assumed to have three uniform heat source blocks. Various cooling methods are considered to find out the efficient cooling method in a given geometry and heat sources. The velocity and the temperature fields. the local temperature distribution along the surface of blocks. and the maximum temperature in each block are obtained. The results are compared to examine the thermal characteristics of the different cooling methods both quantitatively and qualitatively.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.25-29
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• 2008

In automotive disc brake system, friction heat is not uniformly distributed due to various reasons such as thermal expansion and imperfections in geometry. It is well known that thermoelastic distortion due to fictional heating affects the contact pressure distribution and can lead to thermoelastic instability, where the contact load is concentrated in one or more small regions on the brake disc surface. These regions then take very high temperatures and passage of hot spots moving under the brake pads can cause low frequency vibration called brake judder. This paper presents the FEM(finite element method) result for the temperature distribution of ventilated disc brake. A steady state two-dimensional model of disc brake system predicts the surface temperatures during a multi-stop driving schedule.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.69-77
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• 2004

The Gaussian heat source has been widely used to simulate the heat flux of the welding we, and applied to calculating the temperature distribution of a workpiece. The conventional two-dimensional Gaussian heat source for the GMAW is modified in this work by decomposing the arc heat into heats of the cathode and metal transfer. The efficiency and effective arc radius of each heat source are determined analytically for the free-flight mode such as the globular and spray modes. The temperature distribution and weld geometry are calculated using the finite element method, and distribution of the drop heat is found to have significant effects on the penetration. The predicted results show good agreements with the available experimental results, especially with the penetration.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2418-2425
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• 1993

A two-dimensional transient heat transfer model for reactive gas assisted laser cutting process with a moving Gaussian heat source is developed using a numerical finite difference technique. The kerf width, melting front shape and temperature distribution were calculated by using the boundary-fitted coordinate system to handle the ejection of workpiece material and heat input from reaction and evaporation. An analytical solution for cutting front movement was adopted and numerical simulation was performed to calculate the temperature distribution and melting front thickness. To calculate the moving velocity of cutting front, the normal distribution of the cutting gas velocity was used. The kerf width was revealed to be dependent on the cutting velocity, laser power and cutting gas velocity.

• Korea-Australia Rheology Journal
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• v.13 no.2
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• pp.97-106
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• 2001

Three-dimensional flow analysis was performed by using the control volume finite-element method for design of a profile extrusion die. Because polymer melt behavior is complicated and cross-sectional shape of the profile extrusion die is changing continuously, the fluid flow within the die must be analyzed three-dimensionally. A commercially available polypropylene is used for theoretical and experimental investigations. Material properties are assumed to be constant except for the viscosity. The 5-constant modified Cross model is used for the numerical analysis. A test problem is examined in order to verify the accuracy of the numerical method. Simulations are performed for conditions of three different screw speeds and three different die temperatures. Predicted pressure distribution is compared with the experimental measurements and the results of the previous two-dimensional study. The computational results obtained by using three dimensional CVFEM agree with the experimental measurements and are more accurate than those obtained by using the two-dimensional cross-sectional method. The velocity profiles and the temperature distributions within several cross-sections of the die are given as contour plots.