• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.228-235
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• 2001

For standard size of farmland in Korea is small, we have to consume huge labor for cultivation and efficiency of machine is low. We practice the project, which make size of farmland enlarge. For many factors have to consider in design process in case of large-scale farmland, there are difficulties for comparing alternatives if we design it manually. So we need to techniques for establishing various alternatives and choosing the optimum design by the computer. In this study, fixing the boundary of project using the RGIS (Rural Geographical Information System) which standard electronic map in Korea. In the boundary, we analysis the many characteristics of farm land, optimize the adjustment process of field unit of farmland. In this process, we develop automatic farmland division techniques. The results of adapting the developed system show the usefulness to enlarge the size of farmland about 200%.

• Journal of Industrial Technology
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• v.13
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• pp.25-31
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• 1993

This paper presents an analysis of microwave device component. An H-Plane waveguide component with arbitrary shape is analyzed using finite element method(FEM) cooperated with boundary element method(BEM). The finite element method(FEM) is applied to the junction region and the boundary element method(BEM) to the waveguide region. For the application of BEM in the waveguide structure, a ray representation of the waveguide Green's function is used. The proposed technique was applied to the analysis of the waveguide inductive junction to compare the numerical result with the result of the mode matching technique. The comparison showed good agreements between the two results. Transmitted powers were also computed in T-junction waveguides for the various shape of the junction area.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.25-34
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• 1991

An accurate estimation of water level variation when thewaves propagate to the coastal regionis very important for the port and harbor development plan. This study describes the application of a hybrid element model to harbor oscillation problem due to the construction of shore structure and implementation of shore boundary. The site selected is Pusan Harbor area with the third development and the Artificial Island plan. The observed water level changes at the site are compared with the result of the numerical experiment. The model gives a very important prediction of water level changes for navigation and harbor design.

• Journal of Korea Foundry Society
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• v.7 no.3
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• pp.184-191
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• 1987

In this study the principles of melting phenomena of compacted vermicular graphite cast iron are discussed by considering the effects of the variation of phosphorus content and heating rate on the quenched microstructure of the specimens. In compacted vermicular graphite cast iron containing little phosphorus, the melting phenomena are found initially at the outer region of austenite shell and subsequently progressed with the diffusion of carbon through the austenite shell without regard to heating rate. But as the phosphorus content was increased over than 0.12wt.%, the melting phenomena initiated at the boundary of eutectic shell and progressed along the contact area between the melt and graphite tips at higher heating rate. At lower heating rate, the melt of steadite dissolved at the lower temperature than that of eutectic was moved toward the graphite through the austenite grain-boundary and promoted melting of graphite and matrix.

• Atmosphere
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• v.23 no.4
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• pp.513-517
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• 2013

In this study, it is first intended to simulate the vertical profile of atmospheric flow in a short wind tunnel. In order to accomplish it, proper devices are designed properly to reduce freestream flow momentum and it is confirmed from the measured velocity profile using hot-wire anemometer that momentum flux of the tunnel free stream can be reduced and desired atmospheric boundary can be created. Second, experiments are performed to identify influences of a surrounding structure measuring correct wind velocity by an anemometer, which are located nearby due to area limitation in actual airport and correction factors are proposed from experimental results. One of findings is that in order to limit the velocity attenuation due to a nearby structure under 10%, wind velocity measuring equipment should be installed at least 6 times of the structure height away from the structure of concern.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.381-384
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• 2002

The free surface flow problem has been one of the most interesting and challenging topic in the area of the naval ship hydrodynamics and ocean engineering field. The problem has been treated mainly in the scope of the potential theory and its governing equation is well known Laplace equation. But in general, the exact solution to the problem is very difficult to obtain because of the nonlinearlity of the free surface boundary condition. Thus the linearized free surface problem has been treated often in the past. But as the computational power increases, there is a growing trend to solve the fully nonlinear free surface problem numerically. In the present study, a time-dependent finite element method is developed to solve the problem. The initial-boundary problem is formulated and replaced by an equivalent variational formulation. Specifically, the computations are made for a highly nonlinear flow phenomena behind a transom stern ship and a vertical strut piercing the free surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.750-750
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• 2001

Todays, according to development of traffics, there are so many tunnels around us. Tunnels are used for trains, subway trains, cars, etc. Especially for subway, all of its routes are tunnels. So the noise of the subway train cannot radiated out of the station and the noise level in the station and train cabin is so high. There are some methods to reduce this noise and one of them is using absorbing materials. But the area of the tunnel and station is very large, so it is important to determine the effective position and amount of absorbing materials before attaching them. In this study, we studied the effect of sound absorbing materials in the tunnel using boundary element method. We applied BEM for general boundary conditions. With BEM calculations, we found the effect of absorbing materials and effective positions for the subway tunnel and station.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.7
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• pp.807-818
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• 1988

This paper proposes new algorithms for the estimation of displacement vector and moving object extraction using difference picture. First, the relations between the boundary of moving objects in two consecutive image and the boundary of difference picture regions are analyzed, then displacement vector estimation algorithm is proposed. Using the estimated displacement vector, moving objects are directly extracted from difference picture. Since the proposed algorithms do not process gray-valued image, they have a short processing time and are suitable to real time processing. From the experimental results, we observed that, if difference picture is wel extracted, the proposecd algorithms work well even in the circumstances of complex background, fast or slow motion, rotation etc., including occlusion where is not moving area.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.10
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• pp.728-734
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• 2001

Delay defects on I/O pads, interconnections of a board, or interconnections among embedded cores can not be tested with the current IEEE 1149.1 boundary scan design. This paper introduces a simple design technique which slightly modifies the TAP controller to test delay defects at system speed. Experimental design shows that the technique proposed requires much less area than a commercial approach.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.494-499
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• 2011

One of the devices to prevent separated flow over a wing or a flap at high angle of attack is a vortex generator. In the present work, we numerically study the flow around a low-profile or micro vortex generator whose height is less than local boundary layer thickness which can delay separation with a minimum drag penalty owing to its very small wetted surface area. As a first step toward a parametric study to efficiently design this MVG flow control system, we simulate the flow around a single MVG on a flat plate. For the simulation, we employ OpenFOAM with Launder-Sharma ${\kappa}$-epsilon model. The analysis results are validated by comparing with experimental results of a rectangular MVG at an angle of attack of 10 degrees whose height is 20% of local boundary layer. Important results and aspects of this numerical study are discussed. We also simulate the flow around rectangular, triangular and trapezoidal MVGs and the results are compared