• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.28 no.4
• /
• pp.360-370
• /
• 1992

In order to analyse the mesh selectivity for the trawl net, the fishing experiment was carried out by the training ship Saebada belonging to the National Fisheries University, in the Southern Korea Sea and the East China Sea from June 1991 to August 1992. The trawl net used in the experiment has the trouser type of cod-end with cover net and the mesh selectivity in the cod-end part. In this report, the species of fishes caught and the catch rate for them in accordance with different mesh sizes were analysed, and the result obtained are summarized as follows: 1) 145 species of aquatic animals were caught in totally 138 times of trawl operations. 2) The number of species mostly not to escape are 28, 22, 19, 16 and 11 respectively, in each opening mesh size, 51.2mm, 70.2mm, 77.6mm, 88.0mm and 111.3mm of cod-end. 3) In view that the use of the opening mesh size above 54mm in cod-end of trawl net in Korea, it is necessary to device a counterplan against the overfishing, for the 22 species of aquatic animals mostly not to escape in the cod-end of the large mesh sizes more than 70.2mm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.2A
• /
• pp.134-141
• /
• 2010

In this paper, we propose a scheduling algorithm to improve the performance of IEEE 802.16 based wireless mesh networks using directional antenna. The performance is presented in terms of throughput of system and delay between each node by varying number of users. The result show that proposed scheduling algorithm improving the performance by reducing the delay of mesh network system. Our work may be useful as a guideline to control the fairness between SSs for multi-hop systems such as multi-hop relay and mesh networks.

• Wind and Structures
• /
• v.1 no.1
• /
• pp.111-125
• /
• 1998

This paper deals with the development of variable-node element and its application to the adaptive h-version mesh refinement-recovery for the incompressible viscous flow analysis. The element which has variable mid-side nodes can be used in generating the transition zone between the refined and unrefined element and efficiently used for the construction of a refined mesh without generating distorted elements. A modified Guassian quadrature is needed to evaluate the element matrices due to the discontinuity of derivatives of the shape functions used for the element. The penalty function method which can reduce the number of the independent variables is adopted for the purpose of computational efficiency and the selective reduced integration is carried out for the convection and pressure terms to preserve the stability of solution. For the economical analysis of transient problems in which the locations to be refined are changed in accordance with the dynamic distribution of velocity gradient, not only the mesh refinement but also the mesh recovery is needed. The numerical examples show that the optimal mesh for the finite element analysis of a wind around the structures can be obtained automatically by the proposed scheme.

• Journal of the Korea Computer Graphics Society
• /
• v.15 no.3
• /
• pp.19-26
• /
• 2009

In this paper, a new adaptive vertex clustering using a KD-tree is presented for 3D mesh partitioning. A vertex clustering is used to divide a huge 3D mesh into several partitions for various mesh processing. An octree-based clustering and K-means clustering are currently leading techniques. However, the octree-based methods practice uniform space divisions and so each partitioned mesh has non-uniformly distributed number of vertices and the difference in its size. The K-means clustering produces uniformly partitioned meshes but takes much time due to many repetitions and optimizations. Therefore, we propose to use a KD-tree to efficiently partition meshes with uniform number of vertices. The bounding box region of the given mesh is adaptively subdivided according to the number of vertices included and dynamically determined axis. As a result, the partitioned meshes have a property of compactness with uniformly distributed vertices.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.42 no.1
• /
• pp.67-78
• /
• 2005

We proposed a blind watermarking for 3D mesh model using the patch CEGIs. The CEGI is the 3D orientation histogram with complex weight whose magnitude is the mesh area and phase is the normal distance of the mesh from the designated origin. In the proposed algorithm we divide the 3D mesh model into the number of patch that determined adaptively to the shape of model and calculate the patch CEGIs. Some cells for embedding the watermark are selected according to the rank of their magnitudes in each of patches after calculating the respective magnitude distributions of CEGI for each patches of a mesh model. Each of the watermark bit is embedded into cells with the same rank in these patch CEGI. Based on the patch center point and the rank table as watermark key, watermark extraction and realignment process are performed without the original mesh. In the rotated model, we perform the realignment process using Euler angle before the watermark extracting. The results of experiment verify that the proposed algorithm is imperceptible and robust against geometrical attacks of cropping, affine transformation and vertex randomization as well as topological attacks of remeshing and mesh simplification.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1258-1263
• /
• 2004

The present study proposes a new structure for a heat spreader which could embody a thin thickness, any shapes and high heat flux per unit area. It is on the structure for the formation of vapor passages and the support of the case of the heat spreader. A screen mesh is used as the one. To verify the validity of the one, the heat spreader of 1.4mm and 1.6mm thickness was made with 14 mesh and 100 mesh number. In this paper, The performance test of heat spreader conducted in order to compare with the heat transfer performance of conventional heat pipe. As the results, The heat spreader has excellent cooling and heat transfer performance.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.1
• /
• pp.128-132
• /
• 2011

In this paper, two automatic mesh generation algorithms are presented. The methods seek to optimize mesh density with regard to geometries exhibiting both fine and coarse physical structures. When generating meshes, the algorithms attempt to satisfy the conditions on the maximum mesh spacing and the maximum grading ratio simultaneously. Both algorithms successfully produce non-uniform meshes that satisfy the requirements for finite-difference time-domain simulations of microwave components. Additionally, an algorithm successfully generates a minimum number of grid points while maintaining the simulation accuracy.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.216-219
• /
• 2000

본 연구는 WDM Mesh 망에서 SDH 수요가 주어졌을 때, 여러 개의 SDH 수요를 효과적으로 routing하는 방법을 통해 grooming 효과를 극대화시켜 전체 Mesh망에서 사용되어지는 총 Lightpath의 수를 줄이는 것을 목적으로 한다. 그리고 이렇게 해서 구해진 Lightpath의 수를 각 링크의 용량제약으로 하여 SDH 수요의 routing 비용을 최소화하는 것을 부차적인 목적으로 한다. 이것을 수리모형으로 바꾸면, Network Synthesis 문제와 Integer Multicommodity 문제로 모형화 할 수 있다. 해법으로는 Path-Formulation을 통한 분지평가법을 사용하였다. 전산실험결과를 보면 상용 패키지인 CPLEX를 이용하여 푼 것에 비해 수행속도 면에서 훨씬 빠르게 나타났고, 문제의 사이즈가 커짐에 따라 CPLEX를 사용하여 해결할 수 없는 문제에 대해서도 해를 구할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.41 no.2
• /
• pp.146-149
• /
• 2017

Si clusters generated during the plasma chemical vapor deposition (CVD) process have a great influence on the quality of the fabricated films. In particular, in hydrogenated amorphous silicon thin films (a-Si:H) used for thin film solar cells, Si clusters are mainly responsible for light-induced degradation. In this study, we investigated the amount of clusters incorporated into thin films using a quartz crystal microbalance (QCM) and specially designed cluster eliminating filters, and investigated the effect of the DC grid mesh in preventing cluster incorporation. Experimental results showed that as the applied voltage of the grid mesh, which is placed between the electrode and the QCM, decreased, the number of clusters incorporated into the film decreased. This is due to the electrostatic force from the grid mesh bias, and this method is expected to contribute to the fabrication of high-quality thin films by preventing Si cluster incorporation.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.705-711
• /
• 2000

This paper presents a fast 3D mesh generation method using a surface based method with a stitching algorithm. This method uses the surface based method since the volume based method that uses 3D Delaunay triangulation can hardly deal with a large scale of scanned points. To reduce the processing time, this method also uses a stitching algorithm: after dividing the whole point data into several sections and performing mesh generation on individual sections, the meshes from several sections are stitched into one mesh. Stitching method prevents the surface based method from increasing the processing time exponentially as the number of the points increases. This method works well with different types of scanned points: a scattered type points from a conventional 3D scanner and a cross-sectional type from CT or MRI.