• 한국문헌정보학회지
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• 제32권2호
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• pp.233-257
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• 1998

교육개혁의 하나로 열린교육을 실시하는 학교가 점차 늘어나고 있다. 그러므로 학교도서관은 열린교육의 교수-학습 과정에 어떻게 효율적으로 참여할 수 있는지 그 방안을 모색해야만 한다. 이 연구는 열린교육에서의 교수-학습과정을 위한 도서관의 능률적인 봉사를 위하여 도서관의 공간을 구성하는 원리와 교사의 교수-학습과정에 참여하기 위한 협동교수프로그램의 절차를 사례와 함께 제시함으로서 사서교사들에게 도움이 되고자 하였다.

• Journal of Communications and Networks
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• 제17권1호
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• pp.40-46
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• 2015

In a mobile ad hoc network (MANET), communication between mobile nodes occurs without centralized control. In this environment the mobility of a node is unpredictable; this is considered as a characteristic of wireless networks. Because of faulty or malicious nodes, the network is vulnerable to routing misbehavior. The resource constrained characteristics of MANETs leads to increased query delay at the time of data access. In this paper, AntHocNet+ Security (ANTSEC) framework is proposed that includes an enhanced cooperative caching scheme embedded with artificial immune system. This framework improves security by injecting immunity into the data packets, improves the packet delivery ratio and reduces end-to-end delay using cross layer design. The issues of node failure and node malfunction are addressed in the cache management.

• 지식경영연구
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• 제14권1호
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• pp.121-132
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• 2013

In education, innovative ways of teaching and learning are always under development and keep being proposed with advanced concepts since the ancient times. Student-centered learning, problem-based learning and cooperative learning have been three major trends under development in secondary education research and practice more than a decade or so. Combined with advanced information and communication technologies, these trends will greatly transform the way we teach and learn in classroom environment and may change the classroom environment itself, into a more interactive and self-centered coaching type environment. In this study, a smart environment that utilizes advanced information technology devices and network is conceptualized, accommodating requirements contained and proposed in the recent trendy pedagogies. Pedagogical cases discussed in these trends are analyzed in detail, producing requirements for such a learning and coaching environment. These requirements are modeled using unified modeling language, leading to a proposal of a basic architecture for an information system supporting this environment.

• Journal of Communications and Networks
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• 제7권3호
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• pp.284-293
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• 2005

A critical issue in applications involving networks of wireless sensors is their ability to synchronize, and mitigate the fading propagation channel effects. Especially when distributed 'slave' sensors (nodes) reach-back to communicate with the 'master' sensor (gateway), low power cooperative schemes are well motivated. Viewing each node as an antenna element in a multi-input multi-output (MIMO) multi-antenna system, we design pilot patterns to estimate the multiple carrier frequency offsets (CFO), and the multiple channels corresponding to each node-gateway link. Our novel pilot scheme consists of non-zero pilot symbols along with zeros, which separate nodes in a time division multiple access (TDMA) fashion, and lead to low complexity schemes because CFO and channel estimators per node are decoupled. The resulting training algorithm is not only suitable for wireless sensor networks, but also for synchronization and channel estimation of single- and multi-carrier MIMO systems. We investigate the performance of our estimators analytically, and with simulations.

• Journal of Communications and Networks
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• 제10권2호
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• pp.194-203
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• 2008

This paper considers the multi-input multi-output (MIMO) relay channel where multiple antennas are employed by each terminal. Compared to single-input single-output (SISO) relay channels, MIMO relay channels introduce additional degrees of freedom, making the design and analysis of optimal cooperative strategies more complex. In this paper, a partial cooperation strategy that combines transmit-side message splitting and block-Markov encoding is presented. Lower bounds on capacity that improve on a previously proposed non-cooperative lower bound are derived for Gaussian MIMO relay channels.

• ETRI Journal
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• 제20권2호
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• pp.149-170
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• 1998

Between a wide range of distributed applications, this work is particularly focused on those applications which allow a group of persons, who are geographically distributed, to interact and cooperate exchanging different kind of information in order to realize group activities in a common work environment. In this paper we realized a study of this kind of applications to identify general and functional characteristics which will then enable us to determine their communication requirements. Also, we analyzed the existent support architectures to examine whether they support multimedia cooperative applications. Based on the results of analysis, we proposed a set of communication functions needed additionally to support these applications, using the ODP(Open Distributed Processing) modelling concepts, rules and view points as our global design methodology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권7호
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• pp.2350-2364
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• 2014

This paper addresses the problem of resource allocation in amplify-and-forward (AF) relayed OFDM based cognitive radio networks (CRNs). The purpose of resource allocation is to maximize the overall throughput, while satisfying the constraints on the individual power and the interference induced to the primary users (PUs). Additionally, different from the conventional resource allocation problem, the rate-guarantee constraints of the subcarriers are considered. We formulate the problem as a mixed integer programming task and adopt the dual decomposition technique to obtain an asymptotically optimal power allocation, subcarrier pairing and relay selection. Moreover, we further design a suboptimal algorithm that sacrifices little on performance but could significantly reduce computational complexity. Numerical simulation results confirm the optimality of the proposed algorithms and demonstrate the impact of the different constraints.

• 한국도서관정보학회지
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• 제31권3호
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• pp.185-211
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• 2000

본 고는 북부지역 7개 대학을 중심으로 디지털도서관의 효과적인 구축·활용을 위한 방안을 연구하였다. 우리 나라는 자원이나 공간 등을 공동으로 활용하는 것을 가장 중요한 목표가 되어야 한다. 이러한 방안으로 가장 이상적인 시스템이 지역적 디지털 네트워크의 구성이다. 지역적 디저털도서관 네트워크를 개발하기 위한 도서관간의 설계 목표나 협력해야 할 사항들과 그 모형의 설계를 중심으로 연구하였다.

• Advances in Computational Design
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• 제3권2호
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• pp.191-200
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• 2018

Establishment of an efficient routing technique in multiple-input-multiple-output (MIMO) based mobile ad hoc network (MANET) is a new challenge in wireless communication system to communicate in a complex terrain where permanent infrastructure network implementation is not possible. Due to limited power of mobile nodes, a minimum power consumed routing (MPCR) algorithm is developed which is an integration of cooperative transmission process. This algorithm select relay node and support short distance communication. The performance analysis of proposed routing algorithm increased signal to noise interference ratio (SNIR) resulting effect of cooperative transmission. Finally performance analysis of the proposed algorithm is verified with simulated result.

• ETRI Journal
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• 제40권6호
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• pp.714-725
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• 2018

Destination-assisted jamming (DAJ) is usually used to protect confidential information against untrusted relays and eavesdroppers in wireless networks. In this paper, a DAJ-based untrusted relay network with multiple antennas installed is presented. To increase the secrecy, a joint optimization of beamforming and power allocation at the source and destination is studied. A matched-filter precoder is introduced to maximize the cooperative jamming signal by directing cooperative jamming signals toward untrusted relays. Then, based on generalized singular-value decomposition (GSVD), a novel transmitted precoder for confidential signals is devised to align the signal into the subspace corresponding to the confidential transmission channel. To decouple the precoder design and optimal power allocation, an iterative algorithm is proposed to jointly optimize the above parameters. Numerical results validate the effectiveness of the proposed scheme. Compared with other schemes, the proposed scheme shows significant improvement in terms of security performance.