• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.414-419
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• 2009

Good control of thermal energy helps to increase characteristics and eliminate defects of large cast-forged part, such as large sized forged shell. Thermal energy control is a important factor. We have studied about forging process and after heat treatment process by FEM simulation. There are three ways of process. Changes of temperature and microstructure for forged shell were predicted according to temperature declination in large cast-forged product. So we will be able to choose the proper time from heat treatment conditions by FEM simulation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.57-63
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• 2011

The aim of this study is to analyze turning process using commercial FEM simulation code. Various simulation models of orthogonal cutting process for 3 layers of metallic material have been simulated and analyzed. The workpiece material used for the orthogonal plane-strain metal cutting simulation consists of three layers, which are Allow Tool Steel, Aluminum and Stainless Steel. The finite element model is composed of a deformable workpiece and a rigid tool. The tool penetrates through the workpiece at a constant speed and constant feed rate. As an analytical result, detailed cutting temperature, strain, pressure, residual stress for both a tool and each layer of workpiece were obtained during the turning process. It has been closely observed that the chip flow curve deforms continuously.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.345-348
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• 1999

An arc model based on the N-S equations modified by adding an energy source term to take account of the arc is developed and solved using Taylor-Garlerkin FEM in the present paper. The numerical method is applied to the simulation of the opening procedure of a puffer type GCB. Moving boundary conditions of the arc chamber during operation is taken into account. Numerical predictions of the temperature profiles at different strokes are presented.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.945-947
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• 2003

Various kinds of practical machines using single phase induction motor(SPIM) are necessary to control speed and torque. In particular, capacitor-run type SPIM has constitutional characteristics, the motor torque is changed by auxiliary capacitance variation. In this study, we manifest equivalent model having more simplicity, and study the relation between torque and capacitance value of SPIM. And analyze Magnetic vibration for FEM(Finite Element Method) simulation. Also, We design the experimental controller which is able to speed control accurately by phase angle control of AC input voltage. Through the simulation and experimental results, we confirmed validity of this study.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.155-162
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• 2004

The volume of the metal is not changed for the plastic deformation. For metal forming simulation, rigid-plastic FEM codes are widely used. Updating geometry using Euler method in the simulation, the volume loss is occurred. In this paper, hybrid method is introduced to perform a more accurate simulation reducing computation time. In the proposed hybrid method, RK2 method is used for geometry updating at first time step and after the boundary condition of the node is changed. At the others, Adams-Bashforth or theta method is applied to update geometry. The results show that the simulations of upsetting and side-pressing can be performed within 0.02％.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2002.11a
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• pp.37-40
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• 2002

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.696-702
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• 2010

In many industrial applications, it is very important to control the temperature of the controlled object to the target temperature as closely as possible. Although it is apparent that the great obstacles in controller design are time-delay of the thermal responses of the controlled object and the effect of thermal interference between neighboring heating zones, one more fundamental obstacle is a very large amount of time which is required during repeated experiments in controller design process. Therefore, a convenient simulation environment, which can represent thermal behavior accurately within appropriate time, is needed. In this paper, a prototype of 2D FEM (finite element method) heat transfer simulation environment using MATLAB is constructed to be usefully adopted into industrial applications with temperature controller design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.800-811
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses in details these three aspects of wind noise simulation and recommends appropriate methods to deliver required results at the right time based on i) simulation and experimental data availability, ii) design stage at which a decision must be made and iii) time available to deliver these results. Several simulation methods are used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. Furthermore, a 1D and 2D wavenumber transformation is used to extract key parameters such as the convective and the acoustic component of the turbulent flow from CFD and/or experimental data whenever available. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.967-971
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• 2004

Today, as the demands for home appliances are increasing, the understanding of noise and vibration characteristics have become more important. It is hard to control its vibration and noise characteristics, because its mechanical structure is very complex. In this study a model of reciprocating compressor is developed. Spring, frame, and LDT are modeled as flexible body, and the other parts are modeled as rigid. FEM model of frame is simplified in order to save the simulation time. We validated the simple model by comparing their natural frequencies and mode shapes. Motor torque is applied to a rotor, and the piston is subjected to a gas pressure. The vibrational characteristics of compressor is analyzed with LS-DYNA. Its results are compared with the simulation results of rigid body frame. The effect of LDT is also studied by comparing the vibration of frame with the results of simulation with no LDT.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.59-69
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• 2019

This paper focuses on the numerical simulation of ice abrasion induced by unbreakable ice floe. Under the assumption that unbreakable floes behave as rigid body, the Discrete Element Method (DEM) was applied to simulate the interaction between a fixed structure and ice floes. DEM is a numerical technique which is eligible for computing the motion and effect of a large number of particles. In DEM simulation, individual ice floe was treated as single rigid element which interacts with each other following the given interaction rules. Interactions between the ice floes and structure were defined by soft contact and viscous Coulomb friction laws. To derive the details of the interactions in terms of interaction parameters, the Finite Element Method (FEM) was employed. An abrasion process between a structure and an ice floe was simulated by FEM, and the parameters in DEM such as contact stiffness, contact damping coefficient, etc. were calibrated based on the FEM result. Resultantly, contact length and contact path length, which are the most important factors in ice abrasion prediction, were calculated from both DEM and FEM and compared with each other. The results showed good correspondence between the two results, providing superior numerical efficiency of DEM.