• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.2
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• pp.67-78
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• 2010

An elastic field composed of symmetric cross-ply laminated material is analyzed in roller guided panel. The plane stress elasticity problem is formulated in terms of two displacement parameters with mixed boundary conditions. The numerical solution for two displacement parameters is obtained using a finite element method considering a panel of glass/epoxy laminated composite. Some components of stress and displacement at different sections of panel are displayed. The results makes sure that the formulation developed in this study can be applied to analyze the characteristics of elastic field made of laminated composite under any boundary conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.1026-1035
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• 1987

The injection molding process is used in the fabrication of a large variety of plastic articles. A numerical simulation of the filling stage along the thickness direction is proposed by combining the free surface boundary condition with the relevant governing equations. The mathematical model is based on the equations of continuity, momentum and energy along with inelastic power-law model and relevant boundary conditions. Due to the significant implications for microstructure development in the pro duct, the fountain effect at the advancing free surface is explicitly taken into consideration in the simulation. The model yields data on free surface shape as well as velocity, pressure, temperature and shear stress distributions within the mold cavity. The rearrangement of the velocity and temperature profiles in the vicinity of the melt front is considered in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.253-253
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• 2008

The main purpose of this study is to identify the vibrational characteristics for the LP blades of Korean standard fossil power plants. Modal tests for the 6 stage blade with boundary condition in which the root of blades are constrained with the disk were conducted, and FE analysis was also did with the same boundary condition. The steady-stress and modal analyses for the coupled bladed-disk system of LP turbine stages were completed. The dynamic analysis and fatigue analysis were followed to diagnose the integrity of LP turbine blades.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1459-1462
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• 2007

In this study, vibration characteristics of concrete slab were investigated through FEM analysis. Four different floor plans with the floor area of $100{\sim}130m^2$ were chosen to be analyzed. Boundary conditions of two dimensional finite element models were determined based on the modal test results. Results showed that mode shapes were formed somewhat different according to the floor plan and the contribution of 1st mode on the floor vibration is generally the highest. Through the transient analysis, it was also found that floor plan, expecially connection of the living room with the kitchen, affected the vibration acceleration levels.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.20-27
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• 2001

Recently numerical approaches for wave loads acting on the vertical caisson of breakwater, and resulting wave reflection and transmission coefficients have been performed. Although the numerical studies by Sulisz's(1997) and Kim et al.(2000) are suggested representatively, theoretical formulation for nonlinear wave pressure is not developed yet. And experimental results of Sulisz(1997) revealed that nonlinear uplift pressure on the caisson may be produced largely on the case of caisson founded on the high rubble mound. From the results of this study, the nonlinear theory for the uplift wave pressure acting on the caisson by applying boundary integral method of Green theorem is formulated, and also the characteristics of nonlinear uplift pressure and run-up height on the caisson are evaluated numerically, according to the variations of hydraulic properties of the rubble mound.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.182-187
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• 2018

A low profile asymmetrical fractal boundary patch antenna based on reactive impedance surface (RIS) and a mushroom unit cell (MUC) is proposed and studied for dual band operation. The sides of the square patch antenna are replaced with asymmetrical half circled fractal curves for circular polarization operation at patch mode band. The fractal patch antenna is loaded with MUC for dual band operation. The antenna radiation characteristics are investigated and illustrated with both simulated and experimental results in detail. The 10-dB return loss bandwidth are 8.48% (3.21-3.49 GHz) and 2.59% (2.30-2.36 GHz) at upper and lower resonance frequencies, respectively. The 3-dB axial ratio bandwidth is 4.26% (3.21-3.35 GHz). A close agreement between simulation data with experimental results is observed.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.481-482
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• 2011

New discrete time domain models for the peak current controlled (PCC) power LED drivers in continuous conduction mode include for the first time the effects of time delay in the pulse-width-modulator. Realistic amounts of time delay are found to have significant effects on the average output LED current and on the critical inductor value at the boundary between two conduction modes. Especially, the time delay can provide an accurate LED current for the PCC buck converter with a wide input voltage. The models can also predict the critical inductor values at the mode boundary as functions of the input voltage and the time delay.

• Journal of computational fluids engineering
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• v.10 no.1
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• pp.80-86
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• 2005

In order to control the transonic flow field with a shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock-boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.567-569
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• 1992

Design sensitivity analysis is proposed for the optimal shape design of three dimensional magnetostatic problems. The direct differentiation method is introduced for design sensitivity analysis and the boundary element method with reduced magnetic scalar potential as the state variable is used to analyze the magnetic characteristics. In the direct differentiation method, the design sensitivity, defined as the total derivative of the objective function with respect to the design variables, is calculated based on the variation of the state variable with respect to the design variable. And the variation of He state variable is calculated by differentiating the both sides of the system matrix equation obtained by applying boundary element method. Through the numerical example with simple electromagnet, the usefullness is proved.

• Korean Institute of Interior Design Journal
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• v.13 no.4
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• pp.83-91
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• 2004

This study focuses on defining the new meaning of immateriality in the present times expressed on space. The purposes of this study were to examine the characteristics of immateriality showed in commercial interior design in Korea, based on the definition of immateriality concept and the analysis of the way it is expressed. The result of this study is as follows; it categorized characteristic of material expression, space concept and media. Characteristic elements can be classified into 6: transparency, implication, off-gravitation, ambiguity of boundary, temporality, interactivity. Expression of immateriality in commercial interior space was obtained in many different ways, which are identified: new expression of material by reduction of materiality, leveling of transparency, expression of floating status, changeable image, illusion effect, blurring boundary. Immateriality is deeply associated with the elements such as surface, material, media, light, and movement. So it is being recognized as an important design concept in today's pluralist society and will play an important role within the design paradigms for the future.