• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.407-411
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• 2009

This study presents the analysis of the identifications and determinations of the material parameters in the developed model in the former paper and their effects on the stress paths. It was shown that the influences of the parameters, specially involved in the strain rate and the viscous nucleus, were in generally acceptable range. From this point, the model was modified by identifying the plastic yield surface and the viscous yield surface in the same mathematical form. The modified model was successful in simulating stress path.

• Advances in materials Research
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• v.5 no.4
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• pp.205-221
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• 2016

In this article, the buckling responses of functionally graded curved (spherical, cylindrical, hyperbolic and elliptical) shell panels under elevated temperature load are investigated numerically using finite element steps. The effective material properties of the functionally graded shell panel are evaluated using Voigt's micromechanical model through the power-law distribution with and without temperature dependent properties. The mathematical model is developed using the higher-order shear deformation theory in conjunction with Green-Lagrange type nonlinear strain to consider large geometrical distortion under thermal load. The efficacy of the proposed model has been checked and the effects of various geometrical and material parameters on the buckling load are analysed in details.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.648-652
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• 2004

A comparative investigation of an experimental and a simulation of chemical kinetics for NOx removal from dielectric barrier discharges is presented. Several types of dielectric barrier discharges were implemented depending upon the configuration of electrodes. The simulation was based on an approximate mathematical model for plasma cleaning of waste gas. The influence of non uniform distributions of species due to the production of primary active particles in the streamer channel was taken into account. A comparison of observed experimental to the calculated removal efficiency of NOx showed acceptable agreement.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.289-298
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• 2003

Meshfree approximations exhibit significant Potential to solve partial differential equations. Meshfree methods have been successfully applied to various problems which the traditional finite element methods have difficulties to handle including the quasi-static and dynamic fracture, large deformation problems, contact problems, and strain localization problems. Reproducing Kernel Particle Method (RKPM) is used in this research fur to its built-in feature of multi-resolution. the sound mathematical foundation and good numerical performance. A formulation of RKPM is reviewed and numerical examples are given to verify the accuracy of the proposed meshfree method for largely deformed elasto-plastic material.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.101-106
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• 2001

In order to establish the optimum process parameters and diamond saw blade composition for machining natural stone, the chip formation process and the wear process must be understood. Diamond saw blade is one of the most effective, versatile, and extensively used methods of processing rock and other hard materials, such as granite, marble, concrete and asphalt. For many years, it has been known that chip thickness is one of the most significant in the understanding of the sawing process, and other variables such as force and power have been correlated with it. In this study, mathematical relations of a material chipped by a single grit of the saw blade will be undertaken. The material chipping geometries have been mathematically defined and derived as maximum chip thickness.

• 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 the Korean institute of surface engineering
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• v.30 no.4
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• pp.239-247
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• 1997

The electrochemical machining of carbon steel was carried in various electrolytes which contain NACl and $NaCIO_3$. Though electrolyte containg NaCl yields fast machining rate, dimensional control is rather difficult. In the case of electrolyte with $NaCIO_3$, dimensional control of anode shape can be obtained through modification of cathode design. Mathematical modeling is also performed for these systems and agreements are good compared with experimental date. The constant gap experiment butween two electrode yielded faster machining rate than constant cathode moving rate experiment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.7-34
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• 1994

;Recently the sheet forming simulation technology revealed great progress in the sense of practical application in the automotive, electric/electronics and aviation/space industries. The goal of sheet forming simulation is to embedded in the design engineering system which is consisted by the analysis and synthesis modules. This design simulation system predicts the slackness of sheet and estimate the formability, and search the optimum material/forming/structure conditions. This OVER-ALL OPTIMUM DESIGN can be classified as follow; 1. ANALYZING PROCEDURE: Numerical simulation based on nonlinear theories -geometry, material and friction nonlinearities- 2. OPTIMIZATION PROCEDURE: Optimum design based on mathematical programing and AI technologies, those are implemented in CAD/CAM/CAE System - Concurrent Engineering System-. In this paper, four subjects will be discussed; (1) State of arts of computer simulation technologies in Japan. (2)History of sheet forming simulation. (3) Benchmark problems. (4) Future technology in the sheet forming simulation.ation.

• Coupled systems mechanics
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• v.9 no.3
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• pp.201-217
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• 2020

This paper employs differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT) for studying free vibrational characteristics of porous functionally graded (FG) nanoplates coupled by visco-elastic foundation. A secant function based refined plate theory is used for mathematical modeling of the nano-size plate. Two scale factors are included in the formulation for describing size influences based on NSGT. The material properties for FG plate are porosity-dependent and defined employing a modified power-law form. Visco-elastic foundation is presented based on three factors including a viscous layer and two elastic layers.The governing equations achieved by Hamilton's principle are solved implementing DQM. The nanoplate vibration is shown to be affected by porosity, temperature rise,scale factors and viscous damping.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.661-676
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• 2016

This paper presents an elastic/plastic model that neglects strain hardening during loading, but accounts for the Bauschinger effect. These mathematical features of the model represent reasonably well the actual behavior of several materials such as high strength steels. Previous attempts to describe the behavior of this kind of materials have been restricted to a class of boundary value problems in which the state of stress in the plastic region is completely controlled by the yield stress in tension or torsion. In particular, the yield stress is supposed to be constant during loading and the forward plastic strain reduces the yield stress to be used to describe reversed yielding. The new model generalizes this approach on plane stress problems assuming that the material obeys the von Mises yield criterion during loading. Then, the model is adopted to describe reversed yielding in thin hollow discs subject to external pressure.