• Review of KIISC
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• v.25 no.2
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• pp.35-42
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• 2015

현재 우리 사회는 산업혁명(오프라인), 정보화혁명(온라인)을 거쳐 모든 것이 인터넷과 연결되는 사물인터넷(IoT) 기반의 초연결혁명으로 진화하고 있다. 이에 사물인터넷 디바이스 사업자가 제품을 보다 쉽게 인터넷과 연결할 수 있는 사물인터넷 서비스 표준플랫폼에 대한 수요가 높아지고 있다. 본 문서는 스마트마이크로그리드 및 웰니스 응용서비스와의 연동자동화, 지능화를 위한 IoT 브로커(Broker) 시스템의 기능 요구 사항 및 시스템 요구사항을 분석하고 정의한다.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.515-521
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• 2015

This study assessed the degradation of image quality caused by grid artifacts and $moir{\acute{e}}$ pattern artifacts in a stationary grid, and the degradation of image quality caused by cut off artifacts in a moving grid. X-ray images were acquired in a stationary grid and a moving grid with X-ray exposure conditions of 100 cm, 80 kVp, and 30 mA using a CDRAD phantom and a 24 cm thickness acrylic phantom. Observer's perception of X-ray imaging using CDRAD Analyzer was mean 49.36, standard deviation 3.76, maximum 55.56, and minimum 38.67 in the stationary grid, and 47.04, 12.69, 55.56, and 20.89, respectively, in the moving grid. The stationary grid was superior to the moving grid in terms of the mean and standard deviation of observer's perception.

• International Area Studies Review
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• v.22 no.1
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• pp.261-284
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• 2018

Global changeover to renewable energy is an inaugurate initiatives as one of the UN sustainable development goals. But the State alone can not achieve its goal, in particular, countries classified as bad governance. However, when the combination of innovative public-private partnerships including technology and operational innovation can be made, it can provide with rural remote villages of developing countries with more sustainable environment. In other words, we tried to show examples of success in energy supply by reducing costs and increasing marketability through various partnerships(technological innovation benefits). Base on the question, this paper examines the cases of Steama.Co, Ewang'an in Kenya, and Grameen Shakti in Bangladesh, and analyzes the developmental effects of differences in partnership types.

• Journal of KIISE
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• v.43 no.9
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• pp.1026-1033
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• 2016

Path-finding on a grid map is a problem generally addressed in the fields of robotics, intelligent agents, and computer games. As technology advances, virtual game worlds tend to be represented more accurately and more realistically, resulting in an excessive increase in the number of grid tiles and in path-search time. In this study, we propose a path-finding algorithm that allows a prompt response to real-time queries by constructing a reduced state space and by precomputing all possible paths in an offline preprocessing stage. In the preprocessing stage, we vertically decompose free space on the grid map, construct a connectivity graph where nodes are the decomposed regions, and store paths between all pairs of nodes in matrix form. In the real-time query stage, we first find the nodes containing the query points and then retrieve the corresponding stored path. The proposed method is simulated for a set of maps that has been used as a benchmark for grid-based path finding. The simulation results show that the state space and the search time decrease significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.9-18
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• 2006

Advances in wireless network are enabling the development of ubiquitous multimedia services. These multimedia services need efficient platforms to comply with the requirements of mobile computing. We introduce an adaptive service platform based on mobile agent and grid systems while specifying the challenges of ubiquitous multimedia services and focusing on frequent disconnections and scarce resources. We applied our platform to framework RtoA (Ready-to-Attend) which supports mobile users to access compute-intensive multimedia service, specifically, mobile education and video conferencing. RtoA includes hand-off, speaker and listener service which enable people to attend a conference or a class with satisfying quality of multimedia service. ns-2 based simulation verifies that our scheme is an efficient way to reduce energy consumption of mobile devices and to improve the response time of mobile applications.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.388-397
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• 2012

Recently, one of the received attraction fields in web based service is 'Human Relationship Service' that is called SNS. This relationship map service is able to deliver information to user more easily and visually because it is intuitive data that is linked with offline real world. While past map service put physical real information in the map, present map service is evolving into new communicative platform that expresses social relationship beyond simple search platform that shows real world. In this paper, we propose smart social grid system using sketch map that is based on online map service structure. This system has features such as standardized interface provision for various SNS, use to governance hub tool in case of establishing a personal network through expanded social grid, a role of bridge to mashup software linked with other SNS, user environment construction that reproduces social grid data, and the faster service setup by improved search technology.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.85-92
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• 2015

As computer game maps get more elaborate, path-finding by using $A^*$ algorithm in grid-based game maps becomes bottlenecks of the overall game performance. It is because the search space becomes large as the number of nodes increases with detailed representation in cells. In this paper we propose an efficient pathfinding method in which the computer game maps in a regular grid is converted into the polygon-based representation of the list of vertices and then the visibility information about vertices of polygons can be utilized. The conversion to the polygon-based map does not give any effect to the real-time query process because it is preprocessed offline. The number of visited nodes during search can be reduced dramatically by designing heuristics using visibility information of vertices that make the accuracy of the estimation enhanced. Through simulations, we show that the proposed methods reduce the search space and the search time effectively while maintaining the advantages of the grid-based method.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.253-254
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• 2012

모바일 클라우드 컴퓨팅 기술이 대두 됨에 따라, 모바일 단말기의 이동성과 클라우드의 컴퓨팅 파워 및 스토리지 자원의 장점을 모두 취합하는 어플리케이션 개발이 가능해졌다. 모바일 어플리케이션 사용자에게 클라우드의 존재가 마치 보이지 않는 것처럼 끊김 없이 작은 오버헤드로 전송을 하는 아키텍처를 제안하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.27-35
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• 2019

There is a growing interest in various microgrid solutions that supply electricity 24 hours a day to off-grid areas where are not connected with the main grid, and Korea has many positive effects by constructing overseas microgrids as a country operating the emission trading scheme. Since it is not clear how to obtain load curves that is one of the inputs of the HOMER used to design a microgrid optimization plan, or it is necessary to examine whether electricity is supplied to the peak load level of the areas where have not received the electricity benefits from the viewpoint of the demand management, a methodology should be developed to know the load composition ratio and the shape of the daily load curve. In this paper, the relative coefficient and average load information for each load group obtained from the survey are used besides peak load and total average load. A mathematical model is proposed to derive the load composition ratio in the form of a Quadratic Programming and the load forecasting is performed using simple linear regression with future indicators. The effectiveness of the proposed method is confirmed for the Philippine island region supported by Korea Energy Agency and the Asian Development Bank.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.383-386
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• 2007

This paper describes the design and integration of the wind- fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), storage system and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. The hydrogen is compressed and stored in high pressure tank by hydrogen gas booster system.