• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.335-341
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• 2009

In this paper, review of developed MLS-based finite elements and a proposal for their applications are described. The shape functions and their derivatives of MLS-based finite elements are constructed using Moving-Least Square approximation. In MLS-based finite element, using the adequate influence domain of weight function used in MLS approximation, kronecker delta condition could be satisfied at the element boundary. Moreover, because of the characteristics of MLS approximation, we could easily add extra nodes at an arbitrary position in MLS-based finite elements. For these reasons, until now, several variable-node elements(2D variable element for linear case and quadratic case and 3D variable-node elements) and finite crack elements are developed using MLS-based finite elements concept. MLS-based finite elements could be extended to 2D variable-node triangle element, 2D finite crack triangle element, variable-node shell element, finite crack shell element, and 3D polyhedron element. In this paper, we showed the feasibility of 3D polyhedron element at the case of femur meshing.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.185-185
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• 2011

Mapping of artificial levee lines, one of major tasks in river zone mapping, is critical to prevention of river flood, protection of environments and eco systems in river zones. Thus, mapping of artificial levee lines is essential for management and development of river zones. Coastal mapping including river zone mapping has been historically carried out using surveying technologies. Photogrammetry, one of the surveying technologies, is recently used technology for national river zone mapping in Korea. Airborne laser scanning has been used in most advanced countries for coastal mapping due to its ability to penetrate shallow water and its high vertical accuracy. Due to these advantages, use of LiDAR data in coastal mapping is efficient for monitoring and predicting significant topographic change in river zones. This paper introduces a method for construction of a 3D artificial levee line using a set of LiDAR points that uses normal vectors. Multiple steps are involved in this method. First, a 2.5-dimensional Delaunay triangle mesh is generated based on three nearest-neighbor points in the LiDAR data. Second, a median filtering is applied to minimize noise. Third, edge selection algorithms are applied to extract break edges from a Delaunay triangle mesh using two normal vectors. In this research, two methods for edge selection algorithms using hypothesis testing are used to extract break edges. Fourth, intersection edges which are extracted using both methods at the same range are selected as the intersection edge group. Fifth, among intersection edge group, some linear feature edges which are not suitable to compose a levee line are removed as much as possible considering vertical distance, slope and connectivity of an edge. Sixth, with all line segments which are suitable to constitute a levee line, one river levee line segment is connected to another river levee line segment with the end points of both river levee line segments located nearest horizontally and vertically to each other. After linkage of all the river levee line segments, the initial river levee line is generated. Since the initial river levee line consists of the LiDAR points, the pattern of the initial river levee line is being zigzag along the river levee. Thus, for the last step, a algorithm for smoothing the initial river levee line is applied to fit the initial river levee line into the reference line, and the final 3D river levee line is constructed. After the algorithm is completed, the proposed algorithm is applied to construct the 3D river levee line in Zng-San levee nearby Ham-Ahn Bo in Nak-Dong river. Statistical results show that the constructed river levee line generated using a proposed method has high accuracy in comparison to the ground truth. This paper shows that use of LiDAR data for construction of the 3D river levee line for river zone mapping is useful and efficient; and, as a result, it can be replaced with ground surveying method for construction of the 3D river levee line.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.3
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• pp.160-174
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• 2008

In this paper, we propose new coding techniques for photometry data of three-dimensional(3-D) mesh models. We make a good use of geometry and connectivity information to improve coding efficiency of color, normal vector, and texture data. First of all, we determine the coding order of photometry data exploiting connectivity information. Then, we exploit the obtained geometry information of neighboring vortices through the previous process to predict the photometry data. For color coding, the predicted color of the current vertex is computed by a weighted sum of colors for adjacent vortices considering geometrical characteristics between the current vortex and the adjacent vortices at the geometry predictor. For normal vector coding, the normal vector of the current vertex is equal to one of the optimal plane produced by the optimal plane generator with distance equalizer owing to the property of an isosceles triangle. For texture coding, our proposed method removes discontinuity in the texture coordinates and reallocates texture image segments according to the coding order. Simulation results show that the proposed compression schemes provide improved performance over previous works for various 3-D mesh models.

• Journal of Biosystems Engineering
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• v.35 no.4
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• pp.250-256
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• 2010

This study is conducted to analyze the drying characteristics of domestically produced Lycii Fructus for improving drying conditions which was dependant on the shape and materials of drying plate. The materials of the drying plates were steel, aluminum and ABS resin, and each plate was shaped semicircle, quadrangular pyramid, and triangle pyramid. Also, mesh plate, the most general type was included. In other words, 10 kinds of plates were made and tested. The test was conducted at $45^{\circ}C$, for 24 hours and moisture content was measured every 4 hours. The quality of tested Lycii Fructus was measured by colorimeter after drying. The experimental results show that regardless of species of Lycii Fructus, the drying rate of the aluminium plate shaped quadrangular pyramid was fastest, 3.11%w.b./h. Except the mesh plate, the drying rate of most plates was about over 2.52%w.b./h. The quality of Lycii Fructus dried on the aluminium plate shaped quadrangular pyramid was the highest, and it was easiest to separate the dried Lycii Fructus from the aluminum plate shaped quadrangular pyramid.

• Korean Journal of Computational Design and Engineering
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• v.20 no.3
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• pp.238-245
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• 2015

Vulnerability assessment is a process to calculate the damage degree of a combat vehicle when the combat vehicle is attacked by an enemy. When the vehicle is hit, it is necessary to analyze the shot line to calculate which components are damaged and judge whether the armor of the vehicle is penetrated by enemy's warhead. To analyze the shot line efficiently, this paper presents the target modeling and the shot line analysis system to assess vulnerability of the ground combat vehicle. This system is easily able to do several functions: 1) the program reads STL files converted from CAD model which is designed by commercial CAD software. 2) It calculates the intersection between triangle of STL mesh and the shot line, and check if the components of the model are penetrated. 3) This program can visualize the results using OpenGL. The vulnerability assessment using the shot line analysis can be used to model the armor of the combat vehicle and arrange the inner components effectively in the early stage of development of the combat vehicle.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.3
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• pp.185-193
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• 2003

The conventional parallelogram prediction uses only three previously traversed vertices in a single adjacent triangle; thus, the predicted vertex can be located at a biased position. Moreover, vortices on curved surfaces may not be predicted effectively since each parallelogram is assumed to lie on the same plane. In order to improve the prediction performance, we use all the neighboring vertices that precede the current vertex. After we order vortices using a vertex layer traversal algorithm, we estimate the current vertex position based on observations of the previously coded vertex positions in the layer traversal order. The difference between the original and the predicted vertex coordinate values is encoded by a uniform quantizer and an entropy coder. The proposed scheme demonstrates improved coding efficiency for various VRML test data.

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.154-165
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• 1998

In this paper, the mongrel singular element with 6 node triangle and 8 node quadrilateral element with J-integral are developed and applied to the various plane crack problems for the isotropic material. The convergence nature is excellent for various crack size with even coarse mesh using the direct method. But the results of the mongrel element with J-integral are worse than the former's ones. Fracture tests were conducted on precracked CT specimens. Results show that, for 7075-T6 aluminum wing spar materials, the fracture toughness is 31.06 ksi.inch $\frac{1}{2}$ in the L-T direction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.29-37
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• 1993

The extension of the weighted integral method in the area of stochastic finite element analysis is presented. The use of weighted integral method in numerical analysis was extended to CST(constant strain triangle) element by Deodatis to calculate the response variability of 2D stochastic systems. In this paper, the extension of the weighted integral method for general plane-elements is represented. It has been shown that the same mesh used in the deterministic FE analysis can be used in the stochastic FE analysis. Furthermore, because the CST element is a special case which has constant strain-displacement matrix the mingling of CST elements with the other quadrilateral elements in the analysis may also be possible.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.10
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• pp.520-529
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• 2005

A feature-based 3D modeling algorithm is presented in this paper. Since conventional methods use depth-based techniques, they need much time for the image matching to extract depth information. Even feature-based methods have less computation load than that of depth-based ones, the calculation of modeling error about whole pixels within a triangle is needed in feature-based algorithms. It also increase the computation time. Therefore, the proposed algorithm consists of three phases, which are an initial 3D model generation, model evaluation, and model refinement phases, in order to acquire an efficient 3D model. Intensity gradients and incremental Delaunay triangulation are used in the Initial model generation. In this phase, a morphological edge operator is adopted for a fast edge filtering, and the incremental Delaunay triangulation is modified to decrease the computation time by avoiding the calculation errors of whole pixels and selecting a vertex at the near of the centroid within the previous triangle. After the model generation, sparse vertices are matched, then the faces are evaluated with the size, approximation error, and disparity fluctuation of the face in evaluation stage. Thereafter, the faces which have a large error are selectively refined into smaller faces. Experimental results showed that the proposed algorithm could acquire an adaptive model with less modeling errors for both smooth and abrupt areas and could remarkably reduce the model acquisition time.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.401-406
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• 2012

This study was conducted to investigate the effect of cone protective net and the variation of cone and seed characteristics of a unique and rare dwarf stone pine (Pinus pumila Regel) population in Mt. Seorak which is in the southern peripheral of South Korea. Iron protective net (50 mesh, 25 ${\times}$ 25 cm) was effective in reducing birds and rodents damage to conelet, thereby it was possible to safely collect seed genetic resources. Early July was observed to be the most appropriate season to cover conelet with Iron protective net. P. pumila have ovoid-triangle shaped, wingless seeds and indehiscent cones, seeds dissemination is mainly by the hoarding behavior of nutcrackers and rodents. Statistical analysis showed that there were significant differences among individuals within population, and the mean characteristics of the species were 35.3 mm, 25.6 mm, 1.38, 6.6 g and 39.3 ea in the cone length, cone width, cone index, cone weight and in number of seeds per cone, respectively. Coefficients of variations in seed weight and number of seeds per cone were relatively high (21.7%, 21.5%, respectively) compared to other traits. Based on the correlation analysis between cone characteristics and seed characteristics, the length of cone and seed showed a significant positive correlation with the seed size and the seed weight, but the width and thickness of seed showed a negative correlation with the number of seeds per cone.