• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.12
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• pp.659-666
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• 2000

A stereo matching has been an important tool for reconstructing three dimensional terrain. By using stereo matching technique, DEM(Digital Elevaton Map) can be generated by the disparity from a reference image to a target image. Generally disparity map can be evaluated by matching the reference image to the target image and if the role of the reference and the target are interchanged, a different DEM can be obtained. In this paper, we propose a new fusion technique to estimate the optimal DEM by eliminating the false DEM due to occlusion. To detect the false DEM, we utilize two measure of accuracy: self-consistency and cross-correlation score. We test the effectiveness of the proposed methods with a quantitative analysis using simulated images. Experimental result indicate that the proposed methods show 24.4% and 33.1% improvement over either DEM.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.287-300
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• 2008

Airflow distributions along tunnel and over the cross section are critical in selecting installation location of the velocity monitor to obtain the representative data for ventilation as well as fire safety systems. This paper aims at performing CFD and on-site studies to analyze the longitudinal and cross-sectional distributions of the air velocity in tunnels employing longitudinal and semi-transversal ventilation systems. This study can ultimately contribute to selecting the monitor type as well as the optimal installation locations in vehicle tunnel.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.73-85
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• 1999

Yield and fracture are separated in the tensile failure of paper. Failure in the machine direction of photocopy paper is contrasted with failure in the cross-machine direction . The ratios of distortion (shape change) to dilatation (volume change) for individual elements at yield and fracture are described. The ratios of distortion to dilatation are measured and compared to predicted values of the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density factor, samples are prepared from machine direction to cross-machine direction in 15 degree intervals. the strain energy density of individual elements are obtained by the integration of stress from finite element analysis with elastic plus plastic strain energy density theory. Poison's ratio and the angle from the principal material direction have a great effect ion the ratio fo distortion to dilatation in paper. During the yield condition, distortion prevails over dilatation . At fracture, dilatation is at a maximum.

• Agricultural and Biosystems Engineering
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• v.1 no.1
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• pp.1-6
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• 2000

Using the modified DEM (Distinct Element Model), which we proposed, the effect of cross section of tire lug on the tire performance was simulated. Though the DEM has an advantage over the FEM when it is applied to simulate the behavior of discrete assembly of particles such as soil, there was still a problem in the case of conventional DEM, that the simulated movement of particles was too free. We constructed a new mechanical model (modified DEM) which can take account of the effect of adhesion between particles. It is shown that the soil deformation is simulated by the modified DEM better than the conventional DEM. Comparing the simulated soil reaction to the tire lug with the experimental results, the adequate DEM parameters were found. It is also indicated possible to find the effect of lug cross section shape on the tractive performance of tire by the DEM simulation.

• Nuclear Engineering and Technology
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• v.38 no.1
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• pp.69-80
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• 2006

Fluid-elastic instability in an air-water two-phase cross-flow has been experimentally investigated using two different arrays of straight tube bundles: normal square (NS) array and rotated square (RS) array tube bundles with the same pitch-to-diameter ratio of 1.633. Experiments have been performed over wide ranges of mass flux and void fraction. The quantitative tube vibration displacement was measured using a pair of strain gages and the detailed orbit of the tube motion was analyzed from high-speed video recordings. The present study provides the flow pattern, detailed tube vibration response, damping ratio, hydrodynamic mass, and the fluid-elastic instability for each tube bundle. Tube vibration characteristics of the RS array tube bundle in the two-phase flow condition were quite different from those of the NS array tube bundle with respect to the vortex shedding induced vibration and the shape of the oval orbit of the tube motion at the fluid-elastic instability as well as the fluid-elastic instability constant.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.104-108
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• 2000

The paper sets the goal as understanding relationship between usability and subjective preference with the cross- cultural comparison between korea and Japan. Total 42 Korean and japanese housewives participated in the experiment where subjects evaluated their subjective preferences on 16 different variations of computer-simulated microwave ovens. In additions, subjects also performed usability testing over 9 different microwave ovens with 6 different tasks given to users. Subjective preferences and usability were analyzed by Conjoint analysis to identify relative importance of features. The results showed that, in case of Korean subjects, subjective preference has positive relationship with usability (i.e. aesthetically good product also showed better performance in usability testing).However, Japanese subjects showed the tendency that subjectively preferred products are not necessarily evaluated good in usability testing (i.e. god aesthetic is one thing and high usability is another). this difference leads the speculation that culture plays a role in balancing the relationship between aesthetic and functionality.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.155-159
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• 2007

This paper calculates and gives the analysis of electron swarm transport coefficients as described electric conductive characteristics of pure Ar, pure $SiH_4$, $Ar-SiH_4$ mixture gases ($SiH_4$--0.5%, 2.5%, 5%) over the range of E/N =$0.01{\sim}300$[Td], P=0.1, 1, 5.0[Torr] by Monte Carlo the Backward prolongation method of the Boltzmann equation using computer simulation without using expensive equipment. The results have been obtained by using the electron collision cross sections by TOF, PT SST sampling, compared with the experimental data determined by the other author. It also proved the reliability of the electron collision cross sections and shows the practical values of computer simulation.

• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.587-613
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• 2013

A 3-node 3D co-rotational beam element using vectorial rotational variables is employed to consider the geometric nonlinearity in 3D space. To account for shape versatility and reinforced concrete cross-sections, fibre model has been derived and conducted. Numerical integration over the cross-section is performed, considering both normal and shear stresses. In addition, the derivations associated with material nonlinearity are given in terms of elasto-plastic incremental stress-strain relationship for both steel and concrete. Steel reinforcement is treated as elasto-plastic material with Von Mises yield criterion. Compressive concrete behaviour is described by Modified Kent and Park model, while tensile stiffening effect is taken into account as well. Through several numerical examples, it is shown that the proposed 3D co-rotational beam element with fibre model can be used to simulate steel and reinforced concrete framed structures with satisfactory accuracy and efficiency.

• Structural Engineering and Mechanics
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• v.2 no.1
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• pp.63-80
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• 1994

A cable is considered as a system of helical wires and a core with distributed dry friction forces at their interfaces. Deformations of the cable subjected to a uniform bending are analyzed. It is shown that there is a critical bending curvature when a slip at the wire-core interface occurs. It originates at the neutral axis of the cross section of the cable and then spreads symmetrically over the cross section with the increase of bending. The effect of slippage on the cable stiffness is investigated. This model is also used to analyze a cable under the quasi-static cyclic bending. Explicit expression for the hysteretic losses per cycle of bending is derived. Numerical examples are given to show the influence of dry friction and helix angle on the bending stiffness and hysteretic losses in the cable.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.193-196
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• 2007

Energy distribution function for electrons in $SF_6-Ar$ mixtures gas used by Simulation has been analysed over the E/N range 30${\sim}$300[Td] by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6-Ar$ mixtures were measured by time-of-flight (TOF) method. The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.