• Coupled systems mechanics
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• v.8 no.5
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• pp.415-437
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• 2019

The present research deals with two-dimensional axisymmetric deformation in transversely isotropic magneto thermoelastic solid with and without energy dissipation, with two temperature and time-harmonic source. The proposed model is helpful for finding the type of relations between mechanical and thermal fields as most of the structural elements of heavy industries are frequently related to mechanical and thermal stresses at a higher temperature. The Hankel transform has been used to find a solution to the problem. The displacement components, stress components, and temperature distribution with the horizontal distance in the physical domain are calculated numerically. The effect of time-harmonic source and two temperature is depicted graphically on the resulting quantities.

• 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.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.360-365
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• 2007

This work is concerned with the topology optimization of three-dimensional cooling fins or heat sinks. Motivated by earlier success of the Internal Element Connectivity Method (I-ECP) method in two-dimensional problems, the extension of I-ECP to three-dimensional problems is carried out. The main efforts were made to maintain the numerical trouble-free characteristics of I-ECP for full three-dimensional problems; a serious numerical problem appearing in thermal topology optimization is erroneous temperature undershooting. The effectiveness of the present implementation was checked through the design optimization of three-dimensional fins.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.543-546
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• 2001

So far, the design methods of quartz crystal resonator have been developed. Recently, as the electronic package and semiconductor modules become smaller, the need to minimize the sizes of crystal components grows larger. but Minimizing crystal plate sizes has limitations because its temperature-frequency characteristics is worse and unwanted resonances occur. so appropriate design of electrode size and crystal plates is necessary. In this palter, Two-dimensional governing equations for electroded piezoelectric crystal plates with general symmetry have been solved from deduced equations from three-dimensional equations of linear piezoelectricity in most cases. In practice, electroded piezoelectric crystal plates have three-dimensional geometry, so simplified 2-dimensional equations and 2-D modeling are insufficient for explaining its resonance modes and characteristics. So, three-dimensional FEM(finite element method) analysis is done and its effectiveness is verified from analyzing practical crystal resonator model.

• The Journal of the Korean dental association
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• v.12 no.1
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• pp.37-42
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• 1974

To ascertain if the ultrasonic cleaning technique caused any dimensional changes in heat and cold curing and fluid resin denture bases and in addition to evaluate the dimensional changes of the resin denture bases stored in water and air, the author measured the distance between the outsides of two pins embedded in methyl methacrylate test denture bases by mean of 12 inch vernier caliper, accurate to 0.02mm. The results were as follows; (1) Ultrasonic cleaning didn't cause any permanent dimensional changes, but only affected temporary dimensional expansion in 16 test denture bases. (2) Temporary expansion rate caused by 10 minutes' ultrasonic cleaning was 0.29% and at the maximal temperature of the cleaning solution it was 0.64%. (3) The half of the denture bases stored in water showed the dimensional expansion rate of 0.47% while the others stored in air showed the dimensional shrinkage rate of 0.15% after 4 months.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1287-1287
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• 2001

The structure of water molecules in the pure liquid state has been subjected to extensive research for several decades. Questions still remain unanswered, however, and no single model has been found capable of explaining all the anomalies of water. In the present study near-infrared spectra of water in the temperature region 6-$80^{\circ}C$ have been analysed by use of principal component analysis (PCA) and two-dimensional correlation spectroscopy in order to study the dynamic behaviour of the water band centred at 1440 nm, which is due to the combination of symmetric and antisymmetric O-H stretching modes. It has been found that the wavelengths 1412 and 1491 nm account for more than 99% of the spectral variation, representing two major water species with weaker and stronger hydrogen bonds, respectively. A third species located at 1438 nm, whose concentration was relatively constant as a function of temperature, is also indicated. A somewhat distorted two-state structural model for water is suggested.

• Structural Engineering and Mechanics
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• v.81 no.4
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• pp.503-511
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• 2022

In this article, we have examined the effect of fractional order parameter in a two-dimensional orthotropic magneto-thermoelastic solid in generalized thermoelasticity without energy dissipation with fractional order heat transfer in the context of hall current, rotation and two-temperature due to normal force. Laplace and Fourier transform techniques are used to obtain the solution of the problem. The expressions for displacement components, stress components, current density components and conductive temperature are obtained in transformed domain and then in physical domain by using numerical inversion method. The effect of fractional parameter on all the components has been depicted through graphs. Some special cases are also discussed in the present investigation.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.2 no.2
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• pp.97-109
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• 1998

A comparison of the two dimensional heat loss, computed using the analytical method and the finite difference method in two models(i.e. one is a parabolic fin whose parabolic curves meet at the fin center line and the other is a transformed parabolic fin whose tip cuts vertically), is made assuming the analytical method is correct. For these methods, the root temperature and surrounding convection coefficients of these fins are assumed as constants. The results show that the relative errors of the heat loss between the two methods for the parabolic fin whose tip cuts vertically are smaller than those for the one whose tip does not cut. In case of Bi=0.01, the values of the heat loss obtained using a finite difference method are close to those values obtained using the analytical method for both models. The values of the heat loss from both models calculated by using the analytical method are almost the same for given range of non-dimensional fin length in case of Bi = 0.01 and 0.1.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.68-77
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• 1995

The two-dimensional pressure distribution, which is the most important parameter in the casting cleaning installations(CCI), was analyzed using the K-FIX computer program for two-phase flow. Modelling was done using R-Z coordinates for the initial and boundary conditions which don't have periodic influx and efflux, and also there was the electric discharge due to high pressure and temperature. The marked particles were introduced to prodict the structure and the size of main and local moving surfaces. The initial and boundary conditions were modified due to the internal structure of CCI.From the results of numerical analysis, it was shown that the maximum pressure on casting was increased with the increase of a water level. The pressure on casting in the radial direction was higher than that in axial direction. Also, it was proved that by introducing the marked particles it was possible to predict the surface structure in case of two-phase flow.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1783-1788
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• 1994

A comparison of the temperature distributions along the wall and center of the fin and the heat loss from the fin, computed assuming the fin tip is insulated and assuming it is not insulated in a triangular fin, is performed by the two-dimensional forced analytic method. When the fin tip is not insulated, a comparison between forced analytic method and analytic method is made in the heat loss and temperature along the fin wall. The value of Biot number varies from 0.01 to 1.0. The root temperature and surrounding convection coefficients of the fin are assumed as a constant. The results are (1) the analysis on the triangular fin assuming the fin tip is insulated does not produce a good value as compared to that of not-insulated case as the non-dimensional fin length decreases and as the value of Biot number increases and (2) the errors between forced analytic method and analytic method are very small, but the former method is better for computer running time and accuracy.