• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.1-4
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• 2004

The PIV measurements are performed to get the quantitative flow visualization around a road vehicle. The model scaled with 1/48 is located in the middle test section of the closed-loop water tunnel and the measuring system consists of CCD camera, diode laser, synchronizer, and computer. The experimental data are obtained at two Reynolds numbers of 50,000 and 100,000 based on the model length. The quasi-three-dimensional isovorticity surfaces, based on two-dimensional velocity field data, are generated. There is little difference between the results in part of the recirculation region and the vorticity contour according to the Reynolds number. Also a little bit complicated three dimensional flows are predicted behind the road vehicle.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.23 no.3
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• pp.203-210
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• 2019

We present the three-dimensional volume reconstruction model using the modified Cahn-Hilliard equation with a fractional Laplacian. From two-dimensional cross section images such as computed tomography, magnetic resonance imaging slice data, we suggest an algorithm to reconstruct three-dimensional volume surface. By using Laplacian operator with the fractional one, the dynamics is changed to the macroscopic limit of Levy process. We initialize between the two cross section with linear interpolation and then smooth and reconstruct the surface by solving modified Cahn-Hilliard equation. We perform various numerical experiments to compare with the previous research.

• The Korean Journal of Applied Statistics
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• v.19 no.2
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• pp.361-368
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• 2006

There are lots of two and three dimensional graph representing two dimensional categorical data. Among them, Li, et al. (2003) proposed Diamond Graph that projects three dimensional graph into two dimension whereby the third dimension is replaced with a diamond shape whose area and middle and vertical and horizontal lengths represent the outcome. In this paper, we use the Diamond graph to test the independence of two predictor variables for two dimensional data. And this graph could be applied for finding the best fitted log-linear model to three dimensional data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.2
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• pp.45-53
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• 2019

RGB-D SLAM (Simultaneous Localization and Mapping) refers to the technology of using deep camera as a visual sensor for SLAM. In view of the disadvantages of high cost and indefinite scale in the construction of maps for laser sensors and traditional single and binocular cameras, a method for creating three-dimensional map of indoor environment with deep environment data combined with RGB-D SLAM scheme is studied. The method uses a mobile robot system equipped with a consumer-grade RGB-D sensor (Kinect) to acquire depth data, and then creates indoor three-dimensional point cloud maps in real time through key technologies such as positioning point generation, closed-loop detection, and map construction. The actual field experiment results show that the average error of the point cloud map created by the algorithm is 0.0045m, which ensures the stability of the construction using deep data and can accurately create real-time three-dimensional maps of indoor unknown environment.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.2
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• pp.1-6
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• 1974

The three-dimensional correction factor of the added mass of finite-length elliptic cylinders in vertical vibration in a free surface was calculated. This problem has already been dealt by T. Kumai[5] to contribute to analytical prediction of the three-dimensional correction factor for the added mass in vertical vibration of ships. In Kumai's work, the body boundary condition involved in the appropriate boundary value problem was approximately treated in the course of obtaining the solution. In this work, obtaining the solution derived from mathematically exact treatment of the body boundary condition, the author recalculated the three-dimensional correction factor for length-beam ratio $4{\sim}8$, beam-draught ratio $2.00{\sim}4.50$ and number of nodes from 2 to 7. And the numerical results were compared with both Kumai's results and the author's experimental data for two and three-noded vibrations of the cylinder of beam-draught ratio 2.40 The comparison of the numerical results shows that the author's are always higher than the Kumai's as expected. And the comparison of the numerical results with experimental data shows that the Kumai's numerical results have less deviation in case of two-noded vibration, and that, in case of three-noded vibration, the author's numerical results are in fairly good correspondence.

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.191-201
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• 1999

The interpretation of resistivity data has, so far, mainly been made under the assumption that the earth is of relatively simple structure and then using one or two-dimensional inversion scheme. Since real earth structure and topography are fully three-dimensional and very complicated In nature, however, such assumptions often lead to misinterpretation of the earth structures. In such situations, three-dimensional inversion is probably the only way to get correct image of the earth. In this study, we have developed a three-dimensional inversion code using the finite element solution for the forward problem. The forward modeling algorithm simulates the real field situation with irregular topography. The inverse problem is solved iteratively using the least-squares method with smoothness constraint. Our inversion scheme employs ACB (Active Constraint Balancing) to enhance the resolving power of the inversion. Including Irregular surface topography in the inversion, we can accurately define the earth structures without artifact in the numerical tests. We could get reasonable image of earth structure by Inverting the real field data sets taken over highway bridge construction site.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.2
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• pp.84-90
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• 2014

This paper presents the results of three-dimensional face point cloud smoothing based on a modified anisotropic diffusion method. The focus of this research was to obtain a 3D face point cloud with a smooth texture and number of vertices equal to the number of vertices input during the smoothing process. Different from other methods, such as using a template D face model, modified anisotropic diffusion only uses basic concepts of convolution and filtering which do not require a complex process. In this research, we used 6D point cloud face data where the first 3D point cloud contained data pertaining to noisy x-, y-, and z-coordinate information, and the other 3D point cloud contained data regarding the red, green, and blue pixel layers as an input system. We used vertex selection to modify the original anisotropic diffusion. The results show that our method has improved performance relative to the original anisotropic diffusion method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.2
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• pp.276-286
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• 1995

In this study, pressure drop and heat transfer coefficients were measured in tubes with three dimensional roughness. Dimples were made by rotating the saw-tooth shaped finning disc on the outer tube surface. Resultant dimple shape was oval. Friction and heat transfer tests were performed with a range of roughness variables-roughness height 'e', axial roughness pitch 'p', circumferential roughness pitch 'z'. Within the test range, tube with e=0.5mm, z=5mm, p=3mm performed best. The efficiency ratio(rati of the heat transfer improvement and the pressure drop increase) of the tube approached 1.0 at low Reynolds number, and it was higher than that of the two-dimensional roughess tube of the same roughness height. Test data were predicted by 'discrete element method'. Results show that discrete element method underpredicts the friction data by 2% to 32%, and overpredicts the heat transfer data by-12% to 113%.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.432-440
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• 2008

Korean shipbuilders are starting to use three dimensional solid CAD systems to enhance their competitiveness in design and production. Despite many merits, three dimensional CAD systems reveal some problems in pipe-line modeling. Pipe-line modeling is heavily dependent on point data in routing. However, since the models built by sweeping or skinning operations do not have data about points and lines on the surfaces, the point data for routing are currently manually calculated by considering the diameters of the pipes and alignment conditions with other pipes. This process is inefficient and prone to errors. In order to enhance the pipe modeling, this paper presents an Offset Routing Program for a three dimensional CAD system, which aids designers to easily define the start points and to generate the pipe routings using reference objects.

• Tribology and Lubricants
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• v.20 no.5
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• pp.284-291
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• 2004

We present a three-dimensional average flow model considering elastic deformation of pad asperities for chemical mechanical planarization. To consider the contact deformation of pad asperities in the calculation of the flow factor, three-dimensional contact analysis of a semi-infinite solid based on the use of influence functions is conducted from computer generated three dimensional roughness data. The average Reynolds equation and the boundary condition of both force and momentum balance are used to investigate the effect of pad roughness and external pressure conditions on film thickness and wafer position angle.