• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.197-203
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• 2004

In mobile network, the maintenance o( host grouping or the multicast delivery tree for multicasting algorithm becomes a major issues. In this paper, we explore the issues of mobile Multicast scheme using Mobile-IPv6, and addresses case when a mobile host is a source as well as a recipient of a given multicast operation using MLD(Multicast Listener Discovery) scheme, and the proposed MLD-based multicasting protocol asks its HA(Home Agent) to stop forwarding multicast for group using tunneling. We examine and compare our model to existing approaches by proposed cost model, and observe an improved ferformacne.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.36-44
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• 2001

The effects of various tripping structures on turbulent boundary layer subjected to adverse pressure gradient were examined. The profiles are compared to zero pressure gradient and adverse pressure gradient. The increases of tripping structures of height, k are affects almost flow parameter included velocity fluctuation, skin friction coefficient and turbulent boundary thickness.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.244-247
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• 2000

이동 통신 기술의 발전으로, 이동컴퓨팅 환경에서의 데이타 서비스에 대한 수요가 증가하고 있다. 이동 호스트 내에 캐쉬가 존재할 경우, 대역폭의 절약 및 빠른 응답시간을 제공할 수 있지만, 캐쉬 일관성을 유지해야하는 부담이 생긴다. 한 셀 내에 존재하는 수 많은 이동 호스트들의 캐쉬 일관성 유지를 위해서 서버(MSS)가 캐쉬 무효화 보고를 일정시간마다 주기적으로 방송하는 방법은 효과적일 수 있다. 기존에 제시된 무효화 보고에서는 갱신된 데이타의 식별자가 사용되지만, 좀 더 적은 양의 대역폭을 소모하는 효율적인 무효화 보고가 되기 위해서는 데이타들을 그룹핑할 수 있는 방안이 연구되어야 한다. 본 논문에서는 서버의 데이타베이스를 데이타의 식별자 값을 기준으로 여러 구역으로 나누었을 때, 데이타의 갱신이 데이타베이스 내 인근 구역에서 많이 발생할 경우, 이진 트리를 기반으로 하여 효율적인 무효화 보고를 생성하는 방법을 제안하고 그 성능을 평가한다.

• Journal of ILASS-Korea
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• v.9 no.4
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• pp.53-66
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• 2004

An experimental study was carried out in order to investigate the influence of flow conditions on a boundary layer in the near-wake of a flat plate. The flow conditions in the vicinity of the trailing edge that is influenced by upstream condition history are an essential factor that determines the physical characteristics of a near-wake. Tripping wires attached at various positions were selected to change flow conditions of a boundary layer. The flows such as laminar, transitional, and turbulent boundary layer at 0.98C from the leading edge are imposed in order to investigate the evolution of symmetric and asymmetric wake. An x-type hot-wire probe(55P61) is employed to measure at 8 stations in the near-wake. Test results show that the near-wake for the case of a turbulent boundary layer is relatively insensitive to instability after separating at the trailing edge, and Reynolds shear stress in the near-wake for the case of a turbulent boundary layer collapses due to turbulent kinetic energy.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.31-34
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• 2009

유비쿼터스 환경에서 상황인지 능력을 가진 지능적 컴퓨팅 개체들 중 사람에게 의존적이지 않고 독립적으로 행동할 수 있는 개체는 유비쿼터스 로봇으로 볼 수 있다. 이러한 로봇은 최근 상호협력 함으로서 보다 최적화된 서비스를 제공하는 연구가 진행되고 있으며, 또한 다수의 로봇이 포함된 환경일 때는 특정한 작업을 수행하기 위하여 특정 로봇의 선별에 관한 연구가 진행 중이다. 본 논문에서는 유비쿼터스 환경에서 서로 다른 기능과 구조를 가지고 있는 지능형 로봇들이 협력하여 특수한 상황이나 임무를 그룹으로 대처할 수 있는 로봇 그룹핑을 설계하고 이를 구현한 결과에 대하여 기술한다. 다수의 로봇 중에서 특정 임무수행을 위한 로봇의 선별 알고리즘은 Entropy를 이용하여 결정 트리를 생성하였다. 또한 Grouping을 위한 Group Layer를 설계하여 구현하였다.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.175-186
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• 2003

Mobile clients like a PDA need a cache and a spatial index to search and access map data efficiently. When a server transmits spatial objects to a mobile client which has a low storage capacity, some of them can be duplicated in a cache of the mobile client. Moreover, the cost for strong added data in the cache and reconfiguring spatial index is very high in the mobile client with low computing power. The scheme for processing duplicated objects and disturbing tasks of the mobile client which has low computing power is needed. In this paper, we classfy the method for strorng duplicated objects and present the scheme for the both caching objects and reconfiguring a spatial index of cached objects using the clipping technique. We propose the caching system based on an agent in order to distribute the overhead of a mobile client as well as to provide efficiently map services. We design and implement it, and evaluate the performance.

• The KIPS Transactions:PartA
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• v.16A no.4
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• pp.289-298
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• 2009

Generally, RFID systems are composed of one reader and several passive tags, and share the single wireless channel. For this reason, collisions occurwhen more than two tags simultaneously respond to the reader's inquiry. To achieve this problem, many papers, such as QT[8], HCT[10], BSCTTA[2], and QT-BCS[9], have been proposed. In this paper, we propose the tree-based anti-collision algorithm using a bit change sensing unit (TABCS) based on BSCTTA algorithm. The proposed algorithm can identify bits returned from tags through bit change sensing unit, even if multi collisions occur. So, it rapidly generates the unique prefix to indentify each tag, and reduce the total of bits. As the result, the cost of identifying all tag IDs is relatively reduced as compared with existing algorithms. It is verified through simulations that the proposed algorithm surpass other existing algorithms.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.64-76
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• 2019

Aged apartments lack parking space and are suffering from severe parking difficulties due to the increase in the supply of private cars due to the economic improvement. Efficient remodeling technology is required as a way to solve the problem of a shortage of parking spaces, but there is a lack of establishing a technology for remodeling plans that can reflect the characteristics of various parks. This study was conducted to analyze the functions of the parking lot expansion technology using the technology tree and to derive the final technology through the function deployment. As a result of functional deployment of the plan to expand the parking lot, the fifth function was deployed and a total of 22 technologies were derived. Four types of technologies are categorized, four technologies for underground expansion, 12 technologies for underground and ground expansion, two technologies for ground expansion, and four technologies for ground-based expansion. As a result of the functional deployment of the main entrance plan, the fifth function was deployed and derived with 22 technologies. The total technologies were grouped into four categories, four technologies for direct underground entry, 11 technologies for indirect underground entry, three technologies for direct access to ground, and four technologies for indirect entry to ground. Through case verification, the detailed technologies applied to the semi-industrial complex of remodeling were identified and expert surveys and interviews were conducted to verify the adequacy of the technology tree.