• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.289-304
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• 2010

This paper proposes a novel scheme for cooperative spectrum sensing on distributed cognitive radio networks. A fuzzy logic rule - based inference system is proposed to estimate the presence possibility of the licensed user's signal based on the observed energy at each cognitive radio terminal. The estimated results are aggregated to make the final sensing decision at the fusion center. Simulation results show that significant improvement of the spectrum sensing accuracy is achieved by our schemes.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.467-476
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• 2009

웹 기술과 교육 환경의 급속한 발전으로 웹기반 협동학습 시스템이 많은 관심을 받고 있다. 최근에는 협동학습에 학습의 흥미와 능동적 참여를 높일 수 있는 게임을 접목하는 연구들이 등장하고 있다. 이러한 연구들은 게임을 사용하는 TGT 학습 모델에 기반한 것들로 대부분 시스템 설계 제안 수준에 머물렀으며, 구현 연구도 순수 TGT 모델만을 구현해 여러 문제점들을 가지고 있었다. 본 논문에서는 이러한 문제점들을 해결하기 위해 확장된 TGT 모델을 정의하고 이에 기반한 새로운 웹기반 협동학습 시스템을 제안하였다. 확장 부분은 Jigsaw II 모델의 전문가 학습, STAD 모델의 향상점수 아이디어, 피드백 학습을 위한 학습자의 게임 문제 출제 참여 등을 포함한다. 순수 TGT 모델 기반 시스템에 대한 제안 시스템의 유용성을 검증하기 위해 두 시스템을 실제 중학교 두 반에게 적용하여 실험을 하였으며 그 결과 제안 시스템이 비교 시스템보다 더 나은 결과를 보임을 보였다.

• 한국보육지원학회지
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• 제16권1호
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• pp.1-20
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• 2020

Objective: The purpose of this study was to explore the application of the multidisciplinary model, which is customized evidence-based counseling for abused preschool children done by a day care center teacher. Methods: The participants were 16 preschool children which were abused by a day care center teacher and their parents. The data were analyzed by using the Wilcoxon Signed-rank test. Results: The multidisciplinary cooperative service model based on customized evidence-based counseling for abused preschool children, their parents, and day care center teachers was developed. Based on this model, customized evidence-based Post-Traumatic Stress Disorder (PTSD) emergency intervention was provided to preschool children abused by a day care teacher in Incheon. The multidisciplinary cooperative emergency intervention service proved to be effective in reducing emotional and behavioral problems of abused preschool children and enhancing the mental health of parents. Conclusion/Implications: The results of this study indicated that the customized evidence-based counseling for abused preschool children done by a day care center teacher using the multidisciplinary cooperative linkage system would be effective, and that child abuse prevention by day care center teachers and intervention services should be provided systematically at the national level.

• 한국유통학회지:유통연구
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• 제2권1호
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• pp.143-174
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• 1997

The model applied in this paper is based on the theory of economic order quantity (EOQ). EOQ model is introduced to explain the improvement of the transaction efficiency through the cooperative purchase. We examine explicitly how horizontal cooperation affects vertical transactions. A result of the analysis is that a seller can prefer transacting with a cooperative rather than with each buyer separately, even if he reduces the selling price of the product. Without increasing the demand for the product, this result is that dealing with a cooperative, rather than separately with each buyer, decreases the transaction cost for the seller-buyers system, the cost reduction more than off-setting the effect of price decrease on the sellers profit. For a coopative consisting of any number of buyers, Pareto efficient ordering policies that maximize the joint cost saving for the seller-buyers system are identified. We then discuss the conditions under which a cooperative under consideration can be modified to increase efficiency gain. Next, we relax the assumption that all buyers participate in a single cooperative and examine the issue of how many cooperatives, each consisting of a subset of the buyers, should be formed to maximize the total cost saving for the seller-buyers system. Finally, the issue of shapley value to divide the cooperatives gain among its members is discussed.

• 한국통신학회논문지
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• 제31권8A호
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• pp.769-774
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• 2006

선택결합을 갖는 협동 다이버시티 시스템의 성능을 만족시키는 연결노드의 전력제어 범위를 검토하였다. 그리고 전력제한이 있는 연결노드가 시스템의 성능에 미치는 영향을 분석하였다. 레일레이 페이딩 하에서 각 경로의 평균 신호 대 잡음비가 동일할 경우, 연결노드가 하나이며 선택결합을 갖는 협동 다이버시티의 이득은 수신오율 $1{\times}10^{-3}$에서 13.5 dB 이다. 그리고 전력제한이 있는 연결노드는 시스템의 성능에 많은 영향이 있음을 알 수 있었다. 그러므로 ad-hoc 네트워크에서 전력제한이 있는 노드는 협동 다이버시티의 연결노드로 바람직하지 않다.

• 디지털산업정보학회논문지
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• 제11권1호
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• pp.135-144
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• 2015

This study aims to propose an evaluation model that enables cooperative learning using e-Learning system. Even if the teacher and the student are not in the same place at the same time, the team project deliverable submitted by the student to the online system can be viewed by the teacher, enabling the teacher to assess the student not only based on the project but also in many other aspects. The proposed e-learning cooperative learning model allows the development of assessment factors, using such factors in assessment of the student's activities which are performed through the e-learning system, and the feedback of the results to the student so that the student is further motivated for learning. The teacher performs a comprehensive assessment of such factors, which is considered in conjunction with the student's assessment. Implementing the cooperative learning model proposed in this study in various e-learning systems such as Moodle is expected to motivate the student for learning, produces better cooperative learning results, provides greater convenience of assessment to the teacher, and improves fairness of assessment by showing the student's activities in real time.

• Journal of Communications and Networks
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• 제13권3호
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• pp.240-249
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• 2011

Cooperative diversity protocols have attracted a great deal of attention since they are thought to be capable of providing diversity multiplexing tradeoff among single antenna wireless devices. In the high signal-to-noise ratio (SNR) region, cooperation is rarely required; hence, the spectral efficiency of the cooperative protocol can be improved by applying a proper cooperation selection technique. In this paper, we present a simple "cooperation selection" technique based on instantaneous channel measurement to improve the spectral efficiency of cooperative protocols. We show that the same instantaneous channel measurement can also be used for relay selection. In this paper two protocols are proposed-proactive and reactive; the selection of one of these protocols depends on whether the decision of cooperation selection is made before or after the transmission of the source. These protocols can successfully select cooperation along with the best relay from a set of available M relays. If the instantaneous source-to-destination channel is strong enough to support the system requirements, then the source simply transmits to the destination as a noncooperative direct transmission; otherwise, a cooperative transmission with the help of the selected best relay is chosen by the system. Analysis and simulation results show that these protocols can achieve higher order diversity with improved spectral efficiency, i.e., a higher diversity-multiplexing tradeoff in a slow-fading environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5149-5173
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• 2016

Cooperative forwarding has shown a substantial network performance improvement compared to traditional routing in multi-hop wireless network. To further enhance the system throughput, especially in the presence of highly congested multiple cross traffic flows, a promising way is to incorporate the multi-radio multi-channel (MRMC) capability into cooperative forwarding. However, it requires to jointly address multiple issues. These include radio-channel assignment, routing metric computation, candidate relay set selection, candidate relay prioritization, data broadcasting over multi-radio multi-channel, and best relay selection using a coordination scheme. In this paper, we propose a simple and efficient cluster-based cooperative data forwarding (CCDF) which jointly addresses all these issues. We study the performance impact when the same candidate relay set is being used for multiple cross traffic flows in the network. The network simulation shows that the CCDF with MRMC not only retains the advantage of receiver diversity in cooperative forwarding but also minimizes the interference, which therefore further enhances the system throughput for the network with multiple cross traffic flows.

• 대한전자공학회논문지TC
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• 제45권6호
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• pp.13-19
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• 2008

이 논문에서는MIMO(Multi-Input Multi-Out)-OFDM(Orthogonal Frequency Division Multiplexing) 시스템에 다중 안테나를 가진 relay를 적용 할 경우, cooperation 통신을 하기 위한 기법을 제안하고 성능을 분석한다. 이동국과 relay간 뿐만 아니라 relay와 기지국간에도 STC(space time coding)에 의해 MIMO채널이 형성되어 cooperative diversity와 MIMO에 의한 diversity 이득을 함께 얻을 수 있어 시스템의 성능이 크게 향상된다. 또한 이동국과 relay에서 송신전력을 위한 간략화 된 전력할당 기법을 제안하여 이에 따른 시스템의 성능이 향상됨을 분석한다.

• 컴퓨터교육학회논문지
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• 제5권2호
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• pp.101-109
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• 2002

인터넷을 기반으로 한 원격지 학급간 협동 학습 시스템은 원격지 학급을 연결하는 매칭 시스템, 다양한 보상 체계와 상호 작용으로 실질적인 협동 학습이 이루어질 수 있도록 한 커뮤니티 시스템, 개인이나 모둠 및 학습실의 학습 성취도를 평가하고 학습 결과물을 공유할 수 있는 리포트 시스템으로 구성하였다. 특히 협동 학습 과정을 사전 준비 단계, 모둠 구성 단계, 상호 작용 단계, 결과 협의 단계, 평가 정리 단계로 구분하여 시스템에 적용시켰다. 이 시스템은 다양한 상호 작용과 책임 있는 모둠 활동을 제공하므로 교사는 자연스럽게 ICT 활용 교육에 자신감을 갖게 되고, 학생은 정보화 사회에 필요한 기초적인 ICT와 공동체 의식 습득할 것이다.