• ETRI Journal
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• 제29권1호
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• pp.27-35
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• 2007

Energy savings in orthogonal frequency division multiplexing (OFDM) systems is an active research area. In order to achieve a solution, we propose a new cooperative relaying scheme operated on a per subcarrier basis. This scheme improves the bit error rate (BER) performance of the conventional signal-to-noise ratio (SNR)-based selection relaying scheme by substituting SNR with symbol error probability (SEP) to evaluate the received signal quality at the relay more reliably. Since the cooperative relaying provides spatial diversity gain for each subcarrier, thus statistically enhancing the reliability of subcarriers at the destination, the total number of lost subcarriers due to deep fading is reduced. In other words, cooperative relaying can alleviate error symbols in a codeword so that the error correction capability of forward error correction codes can be fully exploited to improve the BER performance (or save transmission energy at a target BER). Monte-Carlo simulations validate the proposed approach.

• 한국비블리아학회지
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• 제19권1호
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• pp.89-111
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• 2008

본 연구는 우리나라의 전국적 도서관 협력체계 구축을 위한 모델을 개발하고 이를 발전시킬 수 있는 제도개선 방안을 제시하는데 있다. 이를 위해 도서관 협력체계에 관한 이론 분석과 국내 외 도서관 협력체계 현황 및 의견 조사를 통해 우리나라 협력체계의 문제점을 분석하고 이를 토대로 지역중심 협력체계를 근거한 전국적 협력체계모형을 제시하였으며 도서관법 등 관련법과 제도의 개선방안을 제시하였다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 1991년도 춘계학술발표대회 논문집
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• pp.173-174
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• 1991

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2001년도 Bulletin of The 5th Asian Design Conference International Symposium on Design Science
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• pp.11.1-11
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• 2001

• 한국군사과학기술학회지
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• 제19권4호
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• pp.517-525
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• 2016

In this research, the effect of the pressure control of cooperative control system with regenerative brake for a military series hybrid-electric vehicle was studied. A cooperative control system with regenerative brake was developed to maximize regenerative energy from electric traction motors of the vehicle. However, the pressure control method of the system was modified to solve a time delay problem and it deteriorates the performance of the system. A Simulink model including the hybrid-electric components, the cooperative control system with regenerative brake, and the vehicle dynamics was developed and used to find a solution. The regenerative energy ratio with respect to the whole brake energy was increased in this research from less than 60 % to over 80 %.

• 대한예방한의학회지
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• 제13권3호
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• pp.29-41
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• 2009

Objectives : This study was performed to compare consciousness of doctors on cooperative practices of western medicine and traditional Korean medicine, and to provide policy implication for development of cooperative practices. Methods : The structured questionnaires were mailed to 132 doctors working in non-cooperative practicing university hospital and 77 doctors working in cooperative practicing hospitals in Busan metropolitan city. The response rate was 40.2% and 40.3% respectively. This survey was performed from 10 Oct. 2008 to 31 Oct. 2008. Results : The doctors working in general hospital had comparatively negative consciousness on basic concept, value and necessity for cooperative practices and traditional Korean medicine. In regards with disease treatment's effectiveness of cooperative practices, both groups evaluated musculoskeletal and immune disease were more effective than others. There were positive relationships between perception for cost-effectiveness and consciousness on intention to participate cooperative practices(p<0.05). Also doctors who experienced traditional medicine treatment had positive consciousness on cooperative practices(p=0.05). Conclusions : To activate cooperative practices of western medicine and traditional Korean medicine, some efforts should be carried out. These include promoting cooperative education programs in medical schools and traditional Korean medical schools, doing research on cost-effectiveness of cooperative practices, and trying to minimize legal and systemic restrictions for cooperative practices.

• 한국수학교육학회지시리즈A:수학교육
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• 제44권3호
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• pp.397-408
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• 2005

This research developed self-directed teaming program for students who learn mathematics to improve their abilities for learning mathematics. A small-group cooperative teaming model was based on the self-directed loaming program which this research developed. The main target of this program was the second grade students of middle school. The program was consisted with three developing parts. The part 1 of program developing was consisted with analyzing and reconstructing mathematics curriculum, devising small-group cooperative learning program, and structuring teaching and teaming plans. The part 2 included the management of small-group cooperative Loaming and how to use the materials which this research developed. The part 3 provided various cooperative learning opportunities for students to improve their abilities for loaming mathematics.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1997년도 Proceedings International Workshop on New Video Media Technology
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• pp.83-88
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• 1997

In this study, we focus on precise and natural cooperative object manipulation in a virtual space. We introduce two virtually expanded physical laws-virtual mechanical equilibrium on a rigid object and exclusive object arrangement-to create realistic cooperative manipulation. We have built a trial system according to our proposed design. The method is expected to allow users to exchange intended manipulation by haptic and visual channels.

• 한국국방경영분석학회지
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• 제27권1호
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• pp.114-127
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• 2001

To support cooperative work in various scenes by computer systems, functions of sharing personalization, observation and control are needed. Especially, in advanced cooperative work, people have various position so that sometimes one person needs to restrict behavior of another. In this paper, we describe representation of access restriction of hypermedia system, which is framework of CSCW(Computer-Supported Cooperative Works) system we developed and propose a way to go on working cooperatively with people, restricting others.

• Journal of Communications and Networks
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• 제10권2호
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• pp.148-155
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• 2008

In wireless data communication systems, retransmission of an erroneous packet is inevitable due to the harsh communication environment. In this paper, an efficient retransmission scheme using cooperation from neighboring nodes is investigated. In the cooperative retransmission scheme, an erroneous packet is transmitted to the destination by cooperative nodes which have favorable channels. This cooperative retransmission scheme requires no a priori information of neighboring nodes and has no limitation on the number of cooperating nodes. Distributed beamforming is used to accommodate multiple cooperating nodes. Phase and frequency offsets of cooperating signals are extracted from the NACK message and used to co-phase retransmitted data packets. The outage probability of the cooperative retransmission scheme is analyzed for the case of perfect synchronization and when the offsets are estimated. To reduce the impact of the residual phase and frequency offsets in cooperating signals, a low-rate feedback scheme is also investigated. It is shown that improved outage probability and reduced packet error rate (PER) performance can be achieved even for long data packets. The proposed cooperative retransmission scheme is found to outperform simple retransmission by the source as well as decode-and-forward cooperation.