• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.39-53
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• 2012

This paper presents an alternative way to derive the exact element stiffness matrix for a beam on Winkler foundation and the fixed-end force vector due to a linearly distributed load. The element flexibility matrix is derived first and forms the core of the exact element stiffness matrix. The governing differential compatibility of the problem is derived using the virtual force principle and solved to obtain the exact moment interpolation functions. The matrix virtual force equation is employed to obtain the exact element flexibility matrix using the exact moment interpolation functions. The so-called "natural" element stiffness matrix is obtained by inverting the exact element flexibility matrix. Two numerical examples are used to verify the accuracy and the efficiency of the natural beam element on Winkler foundation.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.3
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• pp.322-328
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• 2008

Recently, the rapid progress of Internet and Network affects engineering design environment as well as Business fields to utilize Web technologies to enhance it's competitively in the world. In product development, experts and organizations actually taking part in the design process are often geographically dispersed. Furthermore, different divisions and businesses often have heterogeneous CAD/CAE systems and methods for expressing product data, and addressing this heterogeneity creates additional costs and causes longer development periods. To ensure successful collaboration in the design process, it is therefore imperative that distributed CAD, CAE, and other related systems be managed in an organic and integrated manner from the initial stages of product development. Therefore, this study suggests Web-based MDO(Multidisciplinary Design Optimization) framework to support interfacing and the collective use of design and analysis tools.

• ETRI Journal
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• v.26 no.1
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• pp.27-37
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• 2004

The architecture in a differentiated services (DiffServ) network is based on a simple model that applies a per-class service in the core node of the network. However, because the network behavior is simple, the network structure and provisioning is complicated. If a service provider wants dynamic provisioning or a better bandwidth guarantee, the differentiated services network must use a signaling protocol with QoS parameters or an admission control method. Unfortunately, these methods increase the complexity. To overcome the problems with complexity, we investigated scalable dynamic provisioning for admission control in DiffServ networks. We propose a new scalable $qDPM^2$ mechanism based on a centralized bandwidth broker and distributed measurement-based admission control and movable boundary bandwidth management to support heterogeneous QoS requirements in DiffServ networks.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.263-264
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• 2007

In this paper, an efficient SAD(Sum of Absolute Differences) processor structure for motion estimation of 0.264 is proposed. SAD processors are commonly used both in full search methods for motion estimation or in fast search methods for motion estimation. Proposed structure consists of SAD calculator block, combinator block, and minimum value calculator block. Especially, proposed structure is simplified by using Distributed Arithmetic for addition operation. The Verilog-HDL(Hard Description Language) coding and FPGA implementation results for the proposed structure show 39% and 32% gate count reduction comparison with those of the conventional structure, respectively. Due to its efficient processing scheme, the proposed SAD processor structure can be widely used in size dominant H.264 chip.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.43-51
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• 2007

In mobile multi-hop wireless networks, the authentication between a base station and a mobile multi-hop node, between multi-hop nodes, and between user a station and a multi-hop node is needed for the reliable and secure network operation. In this paper, we survey various authentication schemes which can be considered to be adopted in mobile multi-hop wireless networks and propose a concept of novel mutual authentication scheme applicable to mobile multi-hop network architecture. The scheme should resolve the initial trust gain problem of a multi-hop node at its entry to the network, the problem of rogue mobile multi-hop node and the problem of hop-by-hop authentication between multi-hop nodes. Effectively, the scheme is a hybrid scheme of the distributed authentication method and the centralized authentication method which are considered to be deployed in the wireless ad-hoc network and the wireless network connected to wired authentication servers, respectively.

• KIEAE Journal
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• v.2 no.3
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• pp.11-16
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• 2002

Indoor air environment is one of the most important factors that affect resident's health and comfort level. In this paper, the influence of ventilation efficiency with different types of furniture arrangement at breathing zone in a room was analyzed by numerical simulation based on computational fluid dynamics(CFD). The furniture layout of students' bedroom have been classified by three different patterns so that SVE3(scale for ventilation efficiency3) in the rooms was analyzed for air flow distribution. According to the results of the study, SVE3 has the maximum value in spaces between furnitures and each comer of the room. The furniture arrangement influences the ventilation efficiency. It was con finned that ventilation effective in a room is not uniformly distributed as compared the breathing zone with all the area in a room. It means that a study of ventilation efficiency was considered relatively with target zone(a residential or breathing zone) and all the area in a space.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.222-227
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• 2013

This paper presents an analytical framework for dynamic spectrum allocation in cognitive radio networks. We propose a distributed queuing based Markovian model each for single channel and multiple channels access for a contending user. Knowledge about spectrum mobility is one of the most challenging problems in both these setups. To solve this, we consider probabilistic channel availability in case of licensed channel detection for single channel allocation, while variable data rates are considered using channel aggregation technique in the multiple channel access model. These models are designed for a centralized architecture to enable dynamic spectrum allocation and are compared on the basis of access latency and service duration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.843-845
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• 2011

Due to the short lifetime of the battery-based sensor network, study on the environmental energy-harvesting sensor network is being performed widely. In this paper, we analyze the system-level requirements on the sensor node which is needed for the efficient solar-powered wireless sensor network for the target application. In addition, we explain how the HW/SW components of our real solar-powered sensor node can satisfy the requirements mentioned above.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.3
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• pp.305-312
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• 1999

웹의 크기가 지수적으로 증가함에 따라서 각종 정보를 검색하기 위해서는 많은 시간을 필요로 하고 관심있는 특정한 정보를 수시로 검색하는 것은 지루한 일이다. 본 논문에서는 로봇 에이전트를 이용하여 하루의 뉴스 정보를 수집하고 사용자에게 통합된 멀티미디어 뉴스 정보를 제공하는 푸쉬 시스템을 제안한다. 분산 환경 하에 존재하는 푸쉬 서버들을 언어 독립적으로 통합하기 위하여 CORBA(Common Object Request Broker Architecture)를 이용하였다. 이로 인하여 제안된 시스템은 쉽게 확장가능하고 사용자에게 여러 푸쉬 서버에서 수집한 다양한 뉴스 정보를 제공한다. 사용자는 자신의 정보와 원하는 내용을 등록하여 자신이 가장 관심있는 분야의 통합된 뉴스 정보를 멀티미디어 메일을 통해서 제공받을 수 있다.

• Journal of the Korean Institute of Educational Facilities
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• v.21 no.6
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• pp.25-32
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• 2014

Korean academic libraries are facing serious space shortage problems due to an inability to accommodate for the rapidly increasing number of printed materials. Despite the current situation, Korean academic libraries have largely focused on impractical applications of the new library paradigm, using technology or management programs to improve the quality of research and learning environments of the university. However, such improvements would be fruitless without first resolving the space shortage crisis. In order to make realistic improvements to the quality of academic libraries, this study used questionnaires to employ the opinions of librarians currently practicing at such Korean libraries. Survey questionnaires about types and causes of space shortage problems, library facility expansion plans, expected effects of expansion, frequency of and reasons for furniture relocation, and tight spaces needing improvement were distributed to selected 4-year college librarians through Google Drive. Analysis of survey responses indicated that library space shortage was largely responsible for the hindrance of research and learning environments. Furthermore, it reflected the urgency to secure book storage space.