• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.763-770
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• 2000

In this paper, a new stereo image compression algorithm is suggested in which the residual image extracted from the stereo image by the disparity-compensated prediction method is compressed using the wavelet transform considering the inter & intra correlation between subbands. The compression performance of the proposed method is significantly improved by comparing with the conventional algorithm such as EPIC, EPWIC & JPEG through the computer simulation and the PSNR is also increased about 3.5dB compared with the EPIC. Finally, the stereo image having a good 3D effect can be reconstructed from the compressed image data by the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.48-55
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• 1999

In this paper, a zero-dimensional two zone model is developed to investigate the effects of variable valve timing on combustion process in SI engine. The simulation results show that the predicted data has good agreement with experimental ones. The useful information of combustion process such like residual gas fraction cylinder pressure, cylinder temperature and NO concentration can be obtained and the effects of engine variables on combustion processes and performances can be evaluated.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.309-318
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• 1999

In order to fast predict the wind-driven current in a small bay, a convolution method in which the wind-driven current can be generated only wih the local wind is developed and applied in the Sachon Bay. The root mean square(rms) ratio defined as the ratio of the rms error to the rms speed is 0.37. The rms ratio is generally less than 0.2, except for all the mouths of Junju Bay and Namhae-do and in the region between Saryang Island and Sachon. The spatial average of the recover rate of kinetic energy(rrke) is 87%. Thus, the predicted wind-driven current by the convolution model is in a good agreement with the computed one by the numerical model. The raio of the difference between observed residual current (Vr) and predicted wind-driven current (Vc) to a residual current, that is, (Vr-Vc)/Vr shows 56%, 62% at 2 moorings in the Sachon Bay.

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.477-483
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• 2003

An independent kinematic hardening material model in which the reverse yielding point is defined by the Bauschinger effect factor (BEF) , has been defined for stainless steel SUS 304. The material model and the BEF are obtained experimentally and represented mathematically as continuous functions of effective plastic strain. The material model has been incorporated in a non-linear stress analysis for the prediction of reverse yielding in thick-walled cylinders during the autofrettage process of these vessels. Residual stress distributions of the independent kinematic hardening material model at the onset of reverse yielding are compared with residual stresses of an isotropic hardening model showing the significant effect of the BEF on reverse yielding predictions. Critical pressures of direct and reverse yielding are obtained for the most commonly used cylinders and a range of permissible internal pressures for an efficient autofrettaged process is recommended.

• Tribology and Lubricants
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• v.5 no.2
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• pp.60-67
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• 1989

For the life prediction and fatigue failure prevention of the constant velocity joint, the maximum equivalent stress and its location in depth from the contact area are essential. These values give the fundamental information to determine the depth of the surface hardening treatment at the contact area. Contact stresses are evaluated at the surface and subsurface of the ball groove of the Weiss type constant velocity joint. The maximum contact pressure and the maximum equivalent stress are obtained. The effects of various parameters such as the radius of ball groove, friction coefficient, and residual stress are studied. The maximum equivalent stress and the maximum contact pressure increase as the radius of the ball grove increases. The location of the maximum equivalent stress moves toward surface as the friction coefficient increases. It was also found that the maximum equivalent stress becomes minimum when the compressire residual stress is about 0.16 times of the maximum contact pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.146-153
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• 2004

The goals of this study are to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential for characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve are verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.45-48
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• 2005

In manufacturing process of composite cylinders with metal liner, the autofrettage process which induces compressive residual stress on liner to improve cycling life can be applied. In this study, finite element analysis technique is presented, which can predict accurately the compressive residual stress on liner induced by autofrettage and stress behavior after. Material and geometry non-linearity is considered in finite element analysis, and the Von-Mises stress of a liner is introduced as a key parameter that determines pressure cycling life of composite cylinders. Presented methodology is verified through fatigue test of liner material and pressure cycling test of composite cylinders.

• Transactions of Materials Processing
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• v.25 no.2
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• pp.136-140
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• 2016

Although the finite element method is a good tool to analyze skin-pass rolling, it is hard to be applied in the field because of its long calculation time. In the current study, simple numerical models were developed for the prediction of roll force and residual stress profiles along the strip width. These models are based on finite element analysis and a coupled solution of Sims’ equation and Hitchcock’s formula. The results indicate that plastic strains can be represented as in simple equations of the deformed roll profile and the initial thickness of the strip.

• Journal of Welding and Joining
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• v.21 no.5
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• pp.518-524
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• 2003

The block assembly of ship consists of a series of heat processes such as cutting, bending, welding, residual stress relaxation and fairing. With the fast development of computers, the thermal elasto-plastic analysis method has become a versatile tool for practical applications in the ship production. If numerical analysis is proved to be an advantageous tool to predict the residual deformation due to various heat processes, the optimum methods which can remove the welding distortion can be presented at each assembly stage, which will result in great progress in improving the accuracy of block assembly. In order to minimize the weld-induced angular distortion in thick weldments, this paper proposes the optimum groove design for various plate thickness as the distortion control method. The validity of this method has been substantiated by a number of numerical simulations and experiments.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.49-53
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• 2004

Polymeric materials are widely used in the electronic industry as a common dielectric material or adhesive. The polymeric layer coated on Si substrate can be subjected to thermal stresses due to difference in thermal expansion coefficients. The mismatch in thermal properties between the polymeric layer and the substrate results in significant residual stresses. In this study, the thermal deformation is measured by a curvature measurement method using laser scanning, and the elastic modulus is calculated by an analytic model.