• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1055-1063
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• 2002

In this paper, we have studied path selection problem using multiple metric. Current Internet selects a path using only one metric. The path selected by one metric is a best-effort service that can satisfy one requirements. In order to satisfy a call with various Qualify-of-Service(QoS) requirements, the path must satisfy multiple constraints. In many cases, path selection is NP-complete. The proposed algorithm is widest-least cost routing algorithm that selects a path based on cost metric which is basically a delay metric influenced by the network status. The proposed algorithm is a multiple metric path selection algorithm that has traffic distribution ability to select shortest path when network load is light and move traffic to other alternate path when the link load is high. We have compared the results with other routing algorithms.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.5
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• pp.149-157
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• 2008

In the field of computing service, there is a copernican revolution indebted to development of network & computer technology. Computer system, which is set to mainframe in the 1960's, is advancing torwards to the paradigm of server based computing, so-called thin-client. In thin-client computing, network is the platform which is responsible for transfer of application, so that client execute application installed on server. It is also possible that each system share the computing resource connected with network. In this parer, we suggest component & distributed computing technology as a measn for the implementation of thin-client architecture hence, make the best use of COM(Component Object Model and PYRO(PYthon Remote Objects). We talk about the concept and mechanism of thin-client at the beginning, and propose the design of network architecture for the implementation thin-client.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.129.1-129.1
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• 2011

최근 급격한 경제성장과 고도 산업사회로의 전환에 따라 에너지 수요가 크게 증가하고 있다. 이에 따라 석유, 가스 등 화석에너지의 소비량과 온실가스 배출량이 급격히 늘어나고 있는 실정이다. 따라서 화석에너지의 소비와 온실가스 배출을 저감시키기 위해 친환경적인 에너지를 이용하기 위한 많은 연구가 이루어지고 있다. 이와 같은 노력 중 하나가 바로 태양열에너지를 이용하는 방법이다. 태양열에너지는 자원 고갈의 우려가 없고, 에너지의 이용 과정에서 공해 물질을 배출하지 않아 대체 에너지원으로 각광을 받고 있다. 하지만 에너지 밀도가 낮고 에너지의 공급이 기상조건에 따라 큰 영향을 받으므로 태양열에너지를 이용하기 위해서는 효율적인 집열시스템이 필요하다. 따라서 본 연구에서는 우수한 열적특성을 가진 탄소나노유체를 히트파이프 작동유체에 적용하여, 태양열 집열기의 효율을 향상시키기 위해 탄소나노유체의 열전도도 및 점도특성을 비교분석하였다. 나노유체는 에탄올에 산화 다중벽 탄소나노튜브(Oxidized Multi-walled Carbon Nanotubes, OMWCNTs)를 혼합하고, 초음파 분산하여 제조하였다. 에탄올-산화탄소나노유체의 열전도도와 점도는 저온($10^{\circ}C$), 상온($25^{\circ}C$), 고온($70^{\circ}C$)에서 측정하여 비교분석하였으며, 열전도도는 전기 전도성 유체의 비정상 열선법(Transient Hot-wire Method)을 이용하여 측정하였고, 점도는 회전형 디지털 점도계를 이용하였다. 실험 결과 0.1 vol%의 에탄올-산화탄소나노유체의 열전도도는 기본 유체 대비 33.72%($10^{\circ}C$), 33.14%($25^{\circ}C$), 32.26%($70^{\circ}C$)가 향상되었으며, 점도 또한 기본유체보다 크게 증가하지 않아 히트파이프 작동유체로서 우수한 효과를 나타낼 수 있음을 확인하였다. 본 연구의 결과는 태양열 집열기 히트파이프의 효율 향상을 위한 기초자료로써 유용한 정보를 제공할 것이라 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.388-392
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• 2007

지구온단화와 이상기후에 의해 시설물 피해가 나날이 증가하고 있으며, 농촌의 인구감소 및 고령화에 의해 이러한 집중강우등에 대한 대처도 어려운 실정이다. 현재 전국에서 농업용수 공급을 위해 사용하고 있는 농업용 저수지는 17,882개소로서 이 중 축조한지가 35년 이상 경과된 저수지가 15,856개소로서 88.7%나 차지하고 있다. 이러한 현상은 저수지를 구성하고 있는 각종 부대시설의 노후화로 귀결되며 농업용수의 낭비 및 효율적인 운영을 위해서는 시설의 현대화가 필수적이라고 할 수 있다. 따라서 본 연구에서는 저수지에서 물을 직접 공급하는 시설인 사통수문을 대상으로 현대화를 이룩하고 또한 사용동력도 대체에너지를 이용하기 위한 방안을 제시하였다. 사통수문의 수문비는 수중의 압력을 효율적으로 분산시킬 수 있는 원형수문비와 수중에서도 사용동력을 가장 적게 할 수 있는 밸브형을 기준으로 개발을 하였으며, 수문비와 구동부를 연결하는 작동 롯드의 힘전달을 최소화하기 위하여 유니버셜 쪼인트를 볼밸브형으로 개발하였다. 이에 따라서 작동용 롯드의 길이가 길어져도 수문비에 걸리는 작동모멘트를 최소화하여 태양광을 이용한 동력사용이 가능해졌다. 특히 수중에서 움직이는 특성을 감안하여 원형 수문비의 경우에는 수문비와 수문틀 사이에 마찰력을 감소시키기 위하여 수문틀측을 약간 경사지게 가공을 하고 중간에 볼 베이렁을 부착시켜 수문개폐가 원활토록 지수부의 구조변화를 하였다. 또한 농업용수공급시 수류와 함께 유입되는 저수지 내 오물을 차단하기 위하여 수문의 전면에 스크린을 설치하였으며 토사퇴적으로 인하여 수문작동의 방해가 되지 않도록 하기 위하여 토목구조물을 설치하였다. 그리고 동력전달을 효율적으로 하기 위하여 Solar Unit으로부터 나오는 전기를 중전기에서 밧데리로 축전을 시키고 완전 충전 후에는 나머지 전기는 방전이 되도록 회로를 구성하였다. 사통수문 자원조사 결과에 의하면 현재 저수지에 물공급을 하는 수문은 취수탑 형식이 70% 이상을 차지하고 있으며 나머지 30%의 사통수문 중 원형수문비가 98% 이상을 차지하고 있다. 현재 대체에너지를 사용하는 저수지 사통수문은 없는 것으로 조사되었으며 전력을 사용하는 사통도 조사결과에 의하면 20% 이내로 나타났다. 이러한 결과는 향후 수리시설 개보수시 적은 예산으로 사업을 시행하는 경우 사통수문의 설치방향의 지표가 될 것으로 판단되며 수리시설의 운영관리에 대한 새로운 대안으로 제시할 수 있다.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.126-133
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• 2009

The surfactants applied in household detergents and industrial cleansers should satisfy the requirement of not just the basic function such as emulsification, solubilisation, dispersion, detergency, wetting and foaming, but also the economical efficiency and the safety to human and environment. In the viewpoint of the sustainable development, the surfactants, moreover, have to reduce raw materials and energy consumption and waste disposal when they are being manufactured and also consumed for their purposes. New high-performance surfactants have been extensively studied and developed in order to respond the change in social and economical environment. Noticeable progresses have been achieved so far, which are the significant increase in solubility and surface activity through the minor modification of existing surfactant molecular structure and the synergistic increase in a surface activity shown in the mixed surfactant system of anionic and cationic surfactants. In this review, the important and meaningful progresses achieved recently in technological advance and practical application will be summarized and discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.223-232
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• 2004

In this paper we propose the hierarchical-based dynamic bandwidth allocation algorithm for multi-class services in Ethernet-PON. The proposed algorithm consists of the high level scheduler in OLT and the low level scheduler in ONU. The hierarchical architecture is able to provide scalability and resource efficiency in Ethernet-PON which has the distributed nature of the scheduling domain, with queues and the scheduler located at a large distance from each other. We also propose three dynamic bandwidth allocation algorithms for the low level scheduler: Proportional Allocation algorithm, Maximum Request First Allocation (MRFA) algorithm and High Priority First Allocation (HPFA) algorithm. We implement the Ethernet-PON standardized in the IEEE 802,3ah using OPNET. We also evaluate and analyze the performance for the proposed algorithms in terms of channel utilization, queuing delay and the amount of remainder.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.6
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• pp.555-561
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• 2008

This paper describes an e-Engineering framework to support collaborative design of automotive suspension systems developed at KIMM(Korea Institute of Machinery and Materials). The e-Engineering framework is proposed and developed on the base of the multi-layered software agents including engineering task agent which is generated from the domain knowledge of experts. The developed framework is aim to widely spread application to the small and medium enterprises by adopting open source technologies such as JADE (Java Agent Development Framework) and by using the independent characteristics related with applicant H/W and 81W system. This framework can provide an integrated design environment to support distributed personnel, design activities and engineering resources during product development process. For the validation of the system's applicability and efficiency, the several practical design processes for automotive suspension systems of RR/FR lower arms and RR cross member are applied and discussed.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.55-63
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• 2010

On Handoff, existing AP search has chosen one of various APs according to signal strength. However IEEE 802.11 uses Medium Access method with CSMA/CA(Carrier Sensing Multiple Access /Collision Avoidance) that competes to obtain a channel by sharing common medium. For that reason, network performance is heavily affected by the number of nodes and network congestion aside from signal strength. Consequently, in this paper we propose the method that choose one AP which ensures more improved network performance and set up a link, reflecting AP network information in Handoff area, on Handoff in the process of AP selection. We also demonstrate through simulation that it gets maximum performance even in the wireless network which many users concurrently access to, and it has considerable effects on aspects of resources and network management by distribution of users.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.88-101
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• 2018

The collective narratives on global crisis such as the displaced, uneven distribution of resources, invasion of human rights is more than a recurring theme or polemics in the fields of contemporary arts. In the latest projects from Olafur Eliasson, Rirkrit Tiravanija and Ai WeiWei, art works are presented as performative 'platforms' for tackling these undiscriminating reality of human conditions. Here, 'the users' as driving forces of possible change, are postulated as prospective actors/players who lead and collaborate to defy the status-quo. Crossing over the on/off lines, the everyday-activities of exchanging, sharing and networking are strategically deployed and its meaning reconfigured within the context of post/production discourse. This historical, yet unsettling juncture between art and life, dystopian reality and utopian idealism has its formal-conceptual links to Russian Constructivism, Brechtian Learning-Play and Joseph Beuys' Social Sculpture. Based on Nicolas Bourriaud's notion of Postproduction, this paper aims to provide a diachronic analysis on collaborative dispositions of participatory arts practices.

• Journal of the Korean Society for information Management
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• v.20 no.2
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• pp.114-133
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• 2003

Recently, the organizations related to cultural contents are gradually expanding access to cultural contents for general public through the distributed network. However, since cultural contents have different characteristics than general contents, the objects, the of cultural contents seldom contain the words generally used for organization and search of information. If the cultural contents system is created without any consideration of such differences. We cannot effectively identify and search resources. Moreover, because the names, expressions and meanings are different between metadata elements of various cultural contents, it is very difficult to interconnect or share information between different systems. In order to solve these problems, proper organization ad management of metadata is vital. In this studym we have comparatively analyzed the data elements of each format based on Dublin Core, EAD, VRA, CDWA, CIMI, and Object ID, the metadata formats approached from various aspects in the cultural contents area. Through this study, we tried to provide the basic materials for integration of cultural contents by securing interoperability of different metadata formats.