• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.848-860
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• 1994

Generally, to get the minimum distance between two arbitrary shapes that are composed of circular arcs and lines, we must calculate distances for all the possible pairs of the components from two given shapes. In this paper, we propose an efficient method for the minimum distance problem between two shapes by using their structural features after extracting the reduced component lists which are essential to calculate the minimum distance considering the relationship of shape location. Even though the reduced component lists may contain all the components of the shapes in the worst case, in the average we can reduce the required computation much by using the reduced component lists. This method may be efectively applied to calculating the minimum distance between two shapes which are generated by the CAD tool, like in the nesting system.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.676-683
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• 2016

This study was conducted using the Wild -Tracker (WT-300, GPS-Mobile Phone Based Telemetry KoEco) to understand the habitats of the spot-billed duck wintering in urban and rural areas and provide the results as the basic data for the protection and management of the habitats of the waterbirds in Korea. Study areas consisted of the Anseong stream in Gyeonggi-do and the Sansu reservoir in Haenam. Five spot-billed ducks were captured by region, and we attached Wild-Tracker to each of the spot-billed ducks. We analyzed the tracking location data using ArcGIS 9.x and calculated Kernel Density Estimation (KDE) and Minimum Convex Polygon (MCP). The average home-range measured by MCP was $250.8km^2$(SD=195.3, n=5) in Anseong and was $89.1km^2$ (SD=69.6, n=5) in Haenam. 50% home-range measured by KDE was $21.8km^2$ (SD=26.9, n=5) in Anseong and $3.5km^2$ (SD=2.2, n=5) in Haenam, indicating a narrow home range in Haenam. During the winter season, both wetland and paddy field were mostly used as habitats in Anseong and Haenam. While the paddy field utilization rate was high in the daytime in Haenam, it was high in the nighttime in Anseong. By late winter, Haenam's day time paddy field utilization rate and Anseong's night time paddy field utilization rate increased.

• Korean Journal of Environment and Ecology
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• v.33 no.1
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• pp.1-8
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• 2019

Pintail (Anas acuta) is the major wintering bird in South Korea and known as a major mediator of the highly pathogenic avian influenza (HPAI). Pintail migrates long distances between Russian Siberia and Korea. This species prefers a rice paddy area as their winter habitat. The purpose of this study is to provide the data necessary for the conservation and management of bird habitats in Korea by understanding the wintering home-range and habitat of pintail in Korea. We captured six pintails using a cannon-net in the winter of 2015 and attached the GPS-mobile phone based telemetry (WT-300) on them to study the wintering home-range and wintering habitat. We analyzed the tracking location data using ArcGIS 9.0 Animal Movement Extension and calculated Kernel Density Estimation (KDE) and Minimum Convex Polygon (MCP). The average home-range in the wintering ground analyzed by MCP was $677.3km^2$ (SD=130.2, n=6) while the maximum and minimum were $847.7km^2$ and $467.5km^2$, respectively. Extents of home-range analyzed by KDE were $194.7km^2$ (KDE 90%), $77.4km^2$ (KDE 70%), and $35.3km^2$ (KDE 50%). The pintails mostly used both sea and paddy field as habitat in the winter season and utilized paddy fields more during the nighttime and than the daytime. We concluded that the home-range and habitat of pintails in the winter could be used as the reference data for the preservation of species, management of habitats, and coping with a breakout of HPAI.

• Journal of the Korea Computer Graphics Society
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• v.16 no.4
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• pp.25-33
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• 2010

With the popularization of digital photography, people are now capturing and storing far more photos than ever before. However, the enormous number of photos often discourages the users to identify desired photos. In this paper, we present a novel method for fast and intuitive browsing through large collections of geo-referenced photographs. Given a set of photos, we construct a hierarchical structure of clusters such that each cluster includes a set of spatially adjacent photos and its sub-clusters divide the photo set disjointly. For each cluster, we pre-compute its convex hull and the corresponding polygon area. At run-time, this pre-computed data allows us to efficiently visualize only a fraction of the clusters that are inside the current view and have easily recognizable sizes with respect to the current zoom level. Each cluster is displayed as a single polygon representing its convex hull instead of every photo location included in the cluster. The users can quickly transfer from clusters to clusters by simply selecting any interesting clusters. Our system automatically pans and zooms the view until the currently selected cluster fits precisely into the view with a moderate size. Our user study demonstrates that these new visualization and interaction techniques can significantly improve the capability of navigating over large collections of geo-referenced photos.

• Journal of agriculture & life science
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• v.45 no.5
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• pp.41-47
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• 2011

This study was carried out to provide basic information for assessment conditions as habitat to conserve and restore asiatic black bear released in Jirisan National Park. The field investigation at Piagol, Bitjeom, Jangdanggol, Baemsagol, Chilseon valley, and Hanshin valley which checked for habitat of released asiatic black bear were conducted from 2008 to 2010. There were no obvious differences in home range size of asiatic black bear by study year. The seasonal home ranges were analyzed $25.64km^2$ for males and $17.57km^2$ for female in spring, $73.02km^2$ for males and $27.45km^2$ for females in summer, $41.58km^2$ for males and $13.26km^2$ for females in fall, and $6.11km^2$ for males and $2.89km^2$ for females in winter based on 95% Minimum Convex Polygon (MCP) method, respectively. In average elevation by gender of asiatic black bear, the male was higher than the female. respectively. Average elevation by season were $894{\pm}33m$ in spring, $852{\pm}20m$ in summer, $985{\pm}67m$ in fall, and $996{\pm}26m$ in winter, respectively.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.665-670
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• 2003

In the applications like automatic masks generation for semiconductor production, a drawing consists of lots of polygons that are partitioned into trapezoids. The addition/deletion of a polygon to/from the drawing is performed through geometric operations such as insertion, deletion, and search of trapezoids. Depending on partitioning algorithm being used, a polygon can be partitioned differently in terms of shape, size, and so on. So, It's necessary to invent some comparison algorithm of sets of trapezoids in which each set represents interested parts of a drawing. This comparison algorithm, for example, may be used to verify a software program handling geometric objects consisted of trapezoids. In this paper, given k sets of trapezoids in which each set forms the regions of interest of each drawing, we present how to compare the k sets to see if all k sets represent the same geometric scene. When each input set has the same number n of trapezoids, the algorithm proposed has O(2$^{k-2}$ $n^2$(log n＋k)) time complexity. It is also shown that the algorithm suggested has the same time complexity O( $n^2$ log n) as the sweeping-based algorithm when the number k(<< n) of input sets is small. Furthermore, the proposed algorithm can be kn times faster than the sweeping-based algorithm when all the trapezoids in the k input sets are almost the same.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.1890-1900
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• 2017

Tangram game consists of seven pieces of polygons such as triangle, square, and parallelogram. Typical methods of image processing for object recognition may suffer from the existence of side thickness and shadow of the puzzle pieces that are dependent on the pose of 3D-shaped puzzle pieces and the direction of light sources. In this paper, we propose an image processing method that recognizes simple convex polygon-shaped objects irrespective of thickness and pose of puzzle objects. Our key algorithm to remove the thick side of piece of puzzle objects is based on morphological operations followed by logical operations with edge image and background image. By using the proposed object recognition method, we are able to implement a stable tangram game applications designed for tablet computers with front camera. As the experimental results, recognition rate is about 86 percent and recognition time is about 1ms on average. It shows the proposed algorithm is fast and accurate to recognize tangram blocks.

• KIEAE Journal
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• v.14 no.4
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• pp.35-45
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• 2014

The main objective of this study is to provide an effective algorithm of the transmitted solar radiation calculation through window glazing on a clear day. This algorithm would be used in developing a computer program for fenestration system analysis and shading device design. Various simulation methods have been evaluated to figure out the most accurate and effective procedure in estimation of transmitted solar radiation on a tilted surface on a clear day. Characteristics of simulated results of each step have been scrutinized by comparing them with measured results of the site as well as results from other simulation programs. Generally, the Duffie & Beckman's solar calculation method introducing the HDKR anisotropic model provided the most reliable simulation results. The DOE-2 program usually provided over-estimated simulation results. The estimation of extraterrestrial solar radiation and beam normal radiation were conducted pretty accurately. However, the solar radiation either on horizontal surface or on tilted surface involves complicated factors in estimation. Even though the estimation results were close to the real measured data during summer when solar intensity is getting higher, the estimation provided more error when solar intensities were getting weaker. The convex polygon clipping algorithm with homogeneous coordinates was fastest model in calculation of sunlight to shaded area ratio. It could not be applied because of its shape limitation.

• School Mathematics
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• v.15 no.3
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• pp.569-583
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• 2013

In Korea, the school mathematics curricula have been revised in every average 6 years by the government. From the year 2013, the new revised curricula called 2009 version are implied. The subject of elementary mathematics in this new curricula contains four issues to be improved. First, it should be allowed to call the basic figures such as box, cylinder, ball, quadrilateral, triangle and circle in verbal languages. Second, the name of the activities to define mathematical concepts should be changed from 'Yaksok', which means 'promise' in English, to a better and more honest one. Third, the concave polygons should be treated together with the convex ones. Fourth, the calculations of fractions should be weakened as much as possible for the elementary school children.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.285-292
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• 2021

We investigated habitat use and home range of a rescued and released white-naped crane using GPS tracking technology in Cheorwon, South Korea, from October 2016 to March 2017. Four types of roosting sites were identified: frozen reservoirs, paddy fields, rivers, and wetlands. Upon arrival, the white-naped crane preferred wetlands in the Demilitarized Zone (DMZ). In late wintering season, it showed a tendency to change main roosting sites in the following order: rice paddies, rivers, and frozen reservoirs. Among 14 sleeping places, Civilian Control Zone (CCZ) with various type of available habitats was more preferred than the DMZ. Places outside of CCZ were rarely used due to anthropogenic disturbances during the night. The tracked white-naped crane widely chose daytime feeding sites while moving around all over rice paddies in the CCZ. Mean diurnal movement distance was 10.5 km with a maximum of 24.8 km. Its home range measured with Minimum Convex Polygon (MCP) and Kernel Density Estimation (KDE) was 172.30 km² with MCP, 159.60 km² with KDE 95%, 132.48 km² with KDE 90%, and 42.45 km² with KDE 50%. All estimated values of home ranges were higher in the early and later winter than those in the middle period.