• Polymer(Korea)
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• v.28 no.1
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• pp.77-85
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• 2004

It has been widely used ultra high molecular weight polyethylene (UHMWPE) for the biomaterials due to its excellent mechanical properties and biocompatibility. In the case of blend of UHMPE with another polymeric biomaterials, however, UHMWPE might have low blend compatibility due to surface inertness. In this study, in order to improve the mechanical properties of poly(methyl methacrylate) (PMMA) bone cement by means of the impregnation of UHMWPE powder, we developed the novel surface modification method by the mixture of methyl methacrylate (MMA) and xylene. We investigated the variation of composition of MMA/xylene. It was confirmed by the analysis of Fourier transform infrared-attenuated total reflectance, scanning electron microscope, universal transverse mercator, and digital thermometer. The maximum mechanical strength of surface modified UHMWPE powder impregnated PMMA bone cement compound was observed the ratio of 1 : 1 (v/v％) MMA/xylene. Also its curing temperature decreased from 103 $^{\circ}C$ to 58 ∼ 73 $^{\circ}C$ The mechanism of surface modification of UHMWPE powder by the mixture of MMA/xylene has been proposed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.3
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• pp.241-247
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• 2012

The national geodetic reference frame of Korea switched to the International Terrestrial Reference Frame (ITRF) in 2003. In order to study the land area changes, we calculated the entire land area of Korea using the administrative boundaries of census data provided by Statistics Korea. The standard transformation procedure by the National Geographic Information Institute (NGII) was followed. The Transverse Mercator (TM) projected coordinates were transformed into the GRS80-based world geodetic reference frame, and the ellipsoidal and the projected areas were calculated. The provinces that range over two projection origins were divided into two polygons and projected using appropriate origins. After the transformation, all boundaries were shifted in the northwestern direction, resulting in a decreased area of $1.36km^2$ (about 0.0013%) on the projected plane. Moving the boundaries into a high latitude area cancels out the effect of the enlarged ellipsoid. In addition, the rate of change shows that a higher-latitude province is more sensitive to the shift of the boundaries. The data by Statistics Korea is significantly different from those of the Ministry of Land, Transport and Maritime Affairs (MLTM), thus it is urgently recommended that the data are integrated and unified.

• Spatial Information Research
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• v.23 no.2
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• pp.1-9
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• 2015

Graphical processing unit (GPU) contains many arithmetic logic units (ALUs). Because many ALUs can be exploited to process parallel processing, GPU provides efficient data processing. The spatial data require many geographic coordinates to represent the shape of them in a map. The coordinates are usually stored as geodetic longitude and latitude. To display a map in 2-dimensional Cartesian coordinate system, the geodetic longitude and latitude should be converted to the Universal Transverse Mercator (UTM) coordinate system. The conversion to the other coordinate system and the rendering process to represent the converted coordinates to screen use complex floating-point computations. In this paper, we propose a parallel processing technique that processes the conversion and the rendering using the GPU to improve the performance. Large spatial data is stored in the disk on files. To process the large amount of spatial data efficiently, we propose a technique that merges the spatial data files to a large file and access the file with the method of memory mapped file. We implement the proposed technique and perform the experiment with the 747,302,971 points of the TIGER/Line spatial data. The result of the experiment is that the conversion time for the coordinate systems with the GPU is 30.16 times faster than the CPU only method and the rendering time is 80.40 times faster than the CPU.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.1
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• pp.1-11
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• 1999

The Korean government is developing a systematic plan of integrated coastal management for effective conservation, utilization, and development of coastal areas. For this plan, integrated maps of land maps and nautical charts are indispensable. However, these maps are not made, nor studied yet in terms of integration, although digital maps(DM) on land and electronic nautical charts(ENC) have been recently developed by Korean Geography Institute and National Marine Investigation Institute, respectively. In this study, as preliminary studies to make eventual integrated maps, the concept of coastal areas are defined, specifically, coastal lines from DM and ENC are matched against each other. Issues on map production procedures, coordinate systems, and map projections, are carefully considered. A test coastal area located in Seo-Gu, Pusan, over 14 km of coastal lines is selected for the edge matching of coastal lines. RMS differences are 13.83 m and 4.37 m over man-made coastal lines and natural coast lines, respectively, which are quite larger considering a scale difference and other factors. However, no systematic differences are found.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1049-1057
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• 2020

This study aimed to develop a flow measurement method using drone in flood season. Measuring flow in all branches is difficult to conduct annually due to budget and labor limitation, safety and river works. Especially when heavy rain like storm comes, changes in stage-discharge relationship should be reviewed; however, it is usually impeded by the aforementioned issues. To solve the problem, it developed a simple measuring method with a minimum of labor and time. A numeric map and numeric orthophoto coordinate of South Korea are mostly based on Transverse Mercator Projection (TM) in accordance with rectangular coordinate system and use World Geodetic Reference System 1980 (GRS80) oval figure for conversion. Applying a concept of aerial photogrammetry, it located four visible Ground Control Points (GCP) near the river at Uijeongbu-si (Singok Bridge) and Yeongdong-gun (Youngdong 2nd Bridge) station and measured the coordinates using VRS DGPS. Hovering at a same level, drones took orthophoto of water surface at an interval of 3 seconds. It defined the pictures with GRS80 TM coordinate system, a rectangular coordinate system and then conducted an orthometric correction using GCP coordinates. According to X and Y coordinate analysis, it estimated the distance between the floating positions at 3 seconds-intervals and calculated the flow through the flow area according to the flow path. This study attested applicability of the flow measurement method using drone in flood season by applying the rectangular coordinate system based on the concept of aerial photogrammetry.