• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.245-256
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• 2006

Fish community in the Hoengseong Reservoir was investigated from April to October 2005. The total number of fish caught from the period was 8,626 fish representing 22 species and 8 families, using tyke net and trammel net. Besides biomass was 122.9 kg. In the fyke net, 8,168 individuals caught during the period represented 21 species belonged to 8 families, its biomass was 90.6 kg. On the other hand, 458 individuals caught in the trammel net during the period represented 16species belonged to 6 families, its biomass was 26.3 kg. The results showed that the trammel net had lower number of species, individuals, and less biomass compared to those of the tyke net. Number of species confirmed was increased according as mesh size of the net was smaller. Besides, the fyke net with small mesh size was able to collect not only small-sized fish but also large-sized fish so that it was suitable to study qualitative and quantitative analysis of fish fauna in detail. Whereas, the trammel net with proper mesh size was effective to determine composition of fish species in the studied area.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.77-82
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• 2003

Geographic information system extends several teamed circles so for and took in application step. Specially, GIS is applying much in civil engineering works field, and is trying to express terrain numerically and look for true value. It is very important that express terrain, can become important parameter to do three-dimensional analysis in later. We are using irregularity triangulation network mainly to express these terrain. In this study, calculated volume of topography by irregularity triangulation by developed formula.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.148-157
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• 2007

A new method which uses distance fields scheme and marching cube algorithm is proposed in order to get an accurate offset model of arbitrary shapes composed of triangular net. In the method, the space bounding the triangular net is divided into smaller cells. For the efficient calculation of distance fields, valid cells which will generate a portion of offset model are selected previously by the suggested detection algorithm. These valid cells are divided again into much smaller voxels which assure required accuracy. At each voxel distance fields are created by calculating the minimum distances between corner points of voxels and triangular net. After generating the whole distance fields, the offset surface were constructed by using the conventional marching cube algorithm together with mesh smoothing scheme. The effectiveness and validity of this new offset method was demonstrated by performing numerical experiments for the various types of triangular net.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.133-140
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• 2009

Presented in this paper is a method to generate round-endmill toolpaths for sculptured surfaces represented as a triangular mesh model. The proposed method is applicable in toolpath generation for ball-endmills and flat-endmills because the round-endmill is a generalized tool in three-axis NC (numerical control) milling. The method uses a wireframe model as the offset model that represents a cutter location surface. Since wireframe models are relatively simple and fast to calculate, the proposed method can process large models and keep high precision. Intersection points with the wireframe offset model and a tool guide plane are calculated, and intersection curves are constructed by tracing the intersection points. The final step of the method is extracting regular curves from the intersection curves including degenerate and self-intersected segments. The proposed method is implemented and tested, and a practical example is presented.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.134-143
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• 2007

A new approach based on mean value coordinate combined with Laplacian coordinate is proposed for shape deformation of a large polygon model composed of triangular net. In the method, the spherical mean value coordinates for closed control meshes is introduced to describe a vertex in the triangle meshes to be deformed. Furthermore, the well known quardratic least square method for the Laplacian coordinates is employed in order to deform the control meshes. Because the mean value coordinates are continuous and smooth on the interior of control meshes, deforming operation of control meshes change the shape of polygon model while preserving the intrinsic surface detail. The effectiveness and validity of this novel approach was demonstrated by using it to deform large and complex polygon models with arbitrary topologies.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.160-170
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• 2008

Shape morphing is the process of transforming a source shape, through intermediate shapes, into a target shape. Two main problems to be considered in three dimensional shape morphing are vertex correspondence and path interpolation. In this paper, an approach which uses the linear interpolation of the Laplacian coordinates of the source and target meshes is introduced for the determination of more plausible path when two topologically identical shapes are morphed. When two shapes to be morphed are different in shape and topology, a new method which combines shape deformation theory based on Laplacian coordinate and mean value coordinate with distance field theory is proposed for the efficient treatment of vertex correspondence and path interpolation problems. The validity and effectiveness of the suggested method was demonstrated by using it to morph large and complex polygon models including male and female whole body models.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.273-282
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• 2005

A rapidly developed satellite technology is used in comprehensive fields such as spatial data aquisition and applications. Especially a GPS positioning is expected to reinvigorate at the national reference system changes to ITRF (International Terrain Reference Frame). Currently the National Geographic Information Institute (NGII) issues a triangulation point coordinate by separating old and new coordinates and in the year of 2007 it will be scheduled to be changed ITRF. The triangulation point coordinate in Cheju area causes some problems due to the difference original observation and re-observation. Thus in this study a GPS observation is conducted after re-organizing geodetic network based on 1st and 2nd order triangulation in order to check the current triangulation points in Cheju area. After the GPS observation data analysis, stable points were extracted, proposed a geodetic network and its application.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.2 s.12
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• pp.133-141
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• 1998

Terrain modelling is composed of a method using the rectangular grid and another using the triangulated irregular network. The method using the triangulated irregular network is most widely used because it can express the characteristics of the terrain well with only a small amount of information on the terrain and also reduces the rendering time. The process of extracting the surface-specific point and a triangular process is needed to construct such triangulated irregular network. This paper concentrates on the process of extracting the surface-specific point. The 8-direction neighborhood method and other transformed methods of the former method are frequently used to extract the surface-specific point. Another method which eliminates the unnecessary points using the Polygon reduction method is also suggested However, the 8-direction neighborhood method has a big fault of also drawing out some unnecessary points. To resolve such problem, we suggest a method of extracting the surface-specific point using the cross section of the terrain. This method reduces the time to extract the surface-specific point and enables a more precise extraction with less terrain information.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.1 s.35
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• pp.65-74
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• 2006

A rapidly developed satellite technology is used in comprehensive fields such as spatial data aquisition and applications. Especially a GPS positioning is expected to reinvigorate at the national reference system changes to ITRF(International Terrain Reference Frame). Currently the National Geographic Information Institute(NGII) issues a triangulation point coordinate by separating old and new coordinates and in the year of 2007 it will be scheduled to be changed ITRF. The triangulation point coordinate in Cheju area causes some problems due to the difference original observation and re-observation. Thus in this study a GPS observation is conducted after re-organizing geodetic network based on 1st and 2nd order triangulation in order to check the current triangulation points in Cheju area. After the GPS observation data analysis, stable points were extracted, proposed a geodetic network and its application.

• Journal of Marine Life Science
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• v.3 no.1
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• pp.22-30
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• 2018

In this study, pilot study on the introduction of stationary fishery was performed to solve the problem of fisheries resource reduction. The Fyke net, which is a test fishing net was selected considering the environment, operation and management costs of Ulleungdo, conditions that can be operated by small fishing vessels and personnel. As a result of 11 times survey using Fyke net from April to May 2017, 2,735 individuals and 983.4 kg caught and the dominant species were red seabream, yellowtail, olive flounder, mitra squid, horse mackerel, filefish, etc. In conclusion, if the production of squid, which is one of the major fisheries resources of Ulleungdo, is continuously decreased, it is considered that introduction of small-scale stationary fishery such as Fyke net would be useful as a means replace income of fishermen.