• Journal of the Korean School Mathematics Society
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• v.17 no.4
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• pp.697-716
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• 2014

The purpose of this paper is to investigate high school students' learning characteristics which revealed in their learning process of limit using GeoGebra. And we are going to analyze effects of teaching of limit using GeoGebra to high school students' interesting and attitudes for mathematics learning. To do this, we selected three high school students as participants and ask them performing limit learning using GeoGebra. We recorded their problem solving process. Through analyzing their problem solving process relate to their solution, we found the followings: First, students did not logically approach based on mathematical properties or given materials, rather showing tendency decide with self-conscious and intuition. Second, it is possible that former reasoning strategies disturb following reasoning in the process of high school students' mathematics learning. Third, learning process of limit using GeoGebra help high school students to identify and correct their errors relate to limit learning. Forth, learning process of limit using GeoGebra positively effects to high school students' interesting and attitudes for mathematics learning.

• Advanced Composite Materials
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• v.17 no.3
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• pp.247-258
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• 2008

This paper is concerned with the long-term performance of geo-textile (GT) composites in terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were made to investigate the advanced properties of long-term performance related to waste landfill applications. The same experiments were also performed for typical polypropylene and polyester GT and compared to PVA GT/HDPE GM composites. We also develop high performance GT composites with GM by using PVA GT, which is capable of improving the frictional properties and thus enhances long-term performance of GT composites. Experimental study reveals that the friction coefficient of GT composites is relatively large compared with those of polyester and polypropylene non-woven GT as long as the friction media has similar size to the particles of domestic standard earth. In addition, the geo-composites bonded with geo-grid by a chemical process were investigated experimentally in terms of strain evaluation and creep response values. Geo-grid plays an important role as a reinforcing material. Three kinds of geo-grid were prepared as strong yarn polyester and they were woven type, non-woven type, and wrap knitted type. The sample geo-grids were then coated with PVC. The rib tensile strength tests were conducted to evaluate geo-grid products in terms of tensile strength with regard to single rib. The test was performed according to GRI-GGI. It was concluded again from the experiments that the tensile and creep strains of the geo-grid showed such stable values that the geo-grid prepared in this study could protect geo-textile partially in practical structures.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.382-389
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• 2006

Developing context awareness service In these day, It demands high security in context awareness service. So GEO-RBAC that provide user assignment of spatial role, assignment of permission, role schema, role instance and spatial role hierarchy to context awareness service is access control model to perfect in context awareness service. But GEO-RBAC is not considering temporal constraints that have to need context awareness environment. Consequently this paper improves the flexibleness of GEO-RBAC to consider time and period constraints notion and the time of GTRBAC that presents effective access control model. also we propose GEO-RBAC to consider temporal constraints for effective access control despite a various case.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.91-105
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• 2019

Discrete-time Queueing models are frequently utilized to analyze the performance of computing and communication systems. The length of busy period is one of important performance measures for such systems. In this paper, we consider the busy period of the Geo/Geo/1/K queue with a single vacation. We derive the moments of the length of the busy (idle) period, the number of customers who arrive and enter the system during the busy (idle) period and the number of customers who arrive but are lost due to no vacancies in the system for both early arrival system (EAS) and late arrival system (LAS). In order to do this, recursive equations for the joint probability generating function of the busy period of the Geo/Geo/1/K queue starting with n, 1 ≤ n ≤ K, customers, the number of customers who arrive and enter the system, and arrive but are lost during that busy period are constructed. Using the result of the busy period analysis, we also numerically study differences of various performance measures between EAS and LAS. This numerical study shows that the performance gap between EAS and LAS increases as the system capacity K decrease, and the arrival rate (probability) approaches the service rate (probability). This performance gap also decreases as the vacation rate (probability) decrease, but it does not shrink to zero.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.483-486
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• 2022

Real time data exchange and information transmission are becoming more and more important these days. The concept of age of information (AoI) was proposed to quantify the freshness of information about the status of a remote source system. The AoI is defined as the amount of time that a packet experiences since it was generated at the source up to now. This paper analyses the age of information for a discrete time Geo/Geo/1/1 status updating system. The stationary probability distribution for peak AoI is obtained. Freshness ratio of information is also derived. Some numerical results obtained by the analysis are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1225-1234
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• 2009

As the Wenchuan Earthquake was of high magnitude and shallow seismic focus, it caused great damage and serious geo-hazards. By the field investigation and remote-sensing interpretation after the earthquake and by using means of GIS, the distribution of geo-hazards triggered by the earthquake was analyzed and the conclusions are as follows: (1) the earthquake geo-hazards showed the feature of zonal distribution along the earthquake fault zone and linear distribution along the rivers; (2) the distribution of earthquake geo-hazards had a marked hanging wall effect, for the development density of geo-hazards in the hanging wall of earthquake fault was obviously higher than that in the foot wall and the width of strong development zone in the hanging wall was about 10 km; (3) the topographical slope was a main factor which controlled the development of earthquake geo-hazards and a vast majority of geo-hazards were distributed on the slopes of 20 to 50 degrees; (4) the earthquake geo-hazards had a corresponding relationship with the elevation and micro-landform, for most hazards happened in the river valleys and canyon sections below the elevation of 1500 to 2000 m, particularly in the upper segment of canyon sections (namely, the turning point from the dale to the canyon). Thin ridge, isolated or full-face space mountains were most sensitive to the seismic wave, and had a striking amplifying effect. In these areas, collapses and landslides were most likely to develop; (5) the study also showed that different lithologies determined the types of geo-hazards, and usually, landslides occurred in soft rocks, while collapses occurred in hard rocks.

• Journal of Environmental Policy
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• v.14 no.4
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• pp.103-123
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• 2015

To provide effective management policy of geo-heritages, concept of Korean geo-heritage has been organized based on geo-diversity, geo-conservation, geo-tourism, and earth-heritage. In addition, current status of geo-heritage in Korea has been grasped, and categorized. In case GPS (Global Positioning System) coordinates exist, spatial information was constructed as GIS (Geographic Information System). Geo-heritages were classified into a total of six categories of natural monument, scenic site, coastal sand-dune, natural cave, world nature heritage, and other types of geo-heritage. By mapping 991 geo-heritages scattered nationwide using geographical information, all statuses can now be readily identified and enable the analysis of the distribution tendencies and correlation with topography. This study was aimed at searching the political connection based on quantitatively organized and analyzed geo-heritages, which have not been mapped thus far. In addition, this study organized data that have existed only in literature, and presented example verification. Moreover, these can be used as guidelines for the future search, discovery, registration and management of geo-heritage. If additional geo-heritages are discovered in field studies or with satellite images, then more correlations may be identified and help facilitate the research on geo-heritages management plans.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.6
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• pp.579-589
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• 2016

This research focuses on accomplishing analysis problems and issues by examining the policies and systems related to geo-spatial big data which have recently arisen, and suggests political and systemic improvement plan for service activation. To do this, problems and probable issues concerning geo-spatial big data service activation should be analyzed through the examination of precedent studies, policies and planning, pilot projects, the current legislative situation regarding geo-spatial big data, both domestic and abroad. Therefore, eight political and systematical improvement plan proposals are suggested for geo-spatial big data service activation: legislative-related issues regarding geo-spatial big data, establishing an exclusive organization in charge of geospatial big data, setting up systems for cooperative governance, establishing subsequent systems, preparing non-identifying standards for personal information, providing measures for activating civil information, data standardization on geo-spatial big data analysis, developing analysis techniques for geo-spatial big data, etc. Consistent governmental problem-solving approaches should be required to make these suggestions effectively proceed.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.285-287
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• 2010

It is recently enlarged to necessity of 3D spatial information model in urban areas. and in order to that, It is increased to use the terrestrial LiDAR. The Point clouds which are received by terrestrial LiDAR take a relateive coordinate. For transform into absolute coordinate, it carry out GPS surveying. However, it is difficult to geo-referencing of point clouds using the GPS due to high buildings and facilities in urban area. This study suggests a methodology, that is geo-referencing of point clouds which is received from terresstrial LiDAR in urban area and then verified accuracy of geo-referencing of point clouds. In order to geo-Referencing of point clouds which are received in Engineering building of Yonsei Univ., it was be setout through GPS surveying, and then obtained absolute coordinate of real building. Using this coordinate, It was operated geo-referencing of point clouds, verified accuracy between check point and geo-referenced point clouds. As a result, RMSE of check point shows that GPS surveying is 6.9~8.0cm.

• Spatial Information Research
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• v.23 no.6
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• pp.19-29
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• 2015

This study was conducted with the purpose of suggesting the improvement plan of political for activating the Geo-Spatial Big Data Services. To this end, we were review the previous research for Geo-Spatial Big Data and analysis domestic and foreign Geo-Spatial Big Data propulsion system and policy enforcement situation. As a result, we have deduced the problem of insufficient policy of reaction for future Geo-Spatial Big Data, personal information protection and political basis service activation, relevant technology and policy, system for Geo-Spatial Big Data application and establishment, low leveled open government data and sharing system. In succession, we set up a policy direction for solving derived problems and deducted 5 policy issues : setting up a Geo-Spatial Big Data system, improving relevant legal system, developing technic related to Geo-Spatial Big Data, promoting business supporting Geo-Spatial Big Data, creating a convergence sharing system about public DB.