• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.87-90
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• 2007

In cooperative communication systems, the source terminal transmits signal to the destination terminal with the aid of partner terminals. Therefore, the source terminal obtains extra spatial diversity gain. As a result, its performance is enhanced in term of higher achievable transmission rate, the larger coverage range, and the lower bit-error-rate (BER). Space-time codes (STCs) have been applied to cooperative communication systems in distributed fashion, in which the signal is spatially time exploited to obtain gains analogous to those provided by STCs. In this work, we consider the application of orthogonal Space-time Block Codes (OSTBCs) to the cooperative communication systems to further achieve higher diversity gain. The advances of the proposed approach are verified via computer simulations.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.2
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• pp.478-493
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• 2013

This study shows how the organizational culture of fisheries cooperative impacts with empowerment and organizational effectiveness. Result of this study would be utilized in organization management for fisheries cooperative. sample design is based on fisheries cooperative which are registered in korea from October 24 through November 17 in 2012. and total of 195 questionnaires are collected through a personal visit. The result of empirical analysis, organizational culture factor which have an effect on empowerment and organizational effectiveness is the biggest influence to them. At the same time. Sympathy of empowerment factor which have an effect on organizational effectiveness is the biggest influence to it.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.1
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• pp.47-54
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• 2003

The majority of small/medium sized shipbuilders in Korea is poor in capital and then, should be restructured as an efficient production system with low investment. Due to considering this situation, the cooperative work system is proposed, in this study, as more effective production system for small/medium sized shipbuilder The cooperative work system Is the production system that many small/medium sized shipbuilders in a group jointly share the common facilities except minimum equipments and have managerial cooperation such as joint purchase of raw materials. The efficiency of cooperative work system is proved from economic and technical point of view with the case study of FRP shipbuilders of Sapjin industrial complex located at Mokpo area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1319-1335
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• 2017

This paper proposes an opportunistic reporting-based sensing-reporting-throughput optimization scheme that maximizes the spectral efficiency of secondary users (SUs) in cooperative cognitive radio networks with a soft combining rule. The performance of cooperative spectrum sensing depends on the sensing time, the reporting time of transmitting sensing results, and the fusion scheme. While longer sensing time and reporting time improve the sensing performance, this shortens the allowable data transmission time, which in turn degrades the spectral efficiency of SUs. The proposed scheme adopts an opportunistic reporting scheme to restrain the reporting overhead and it jointly controls the sensing-reporting overhead in order to increase the spectral efficiency of SUs. We show that there is a trade-off between the spectral efficiency of SUs and the overheads of cooperative spectrum sensing. The numerical results demonstrate that the proposed scheme significantly outperforms the conventional sensing-throughput optimization schemes when there are many SUs. Moreover, the numerical results show that the sensing-reporting time should be jointly optimized in order to maximize the spectral efficiency of SUs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.361-370
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• 2008

Cooperative relaying permits one or more relay to transmit a signal from the source to the destination, thereby increasing network coverage and spectral efficiency. The performance of cooperative relaying is often measured as outage probability. However, appropriate measure for the channel quality is outage capacity. Although the outage probability for cooperative relaying protocol has been analyzed before, very little research has been addressed for the outage capacity. This paper is the first of its kind to derive a closed-form analytical solution of outage capacity using fixed decode and forward relaying and amplify and forward relaying in dissimilar Rayleigh fading channels, considering channel coefficients known to the receiver side. The analytical results show a tradeoff between the SNR and the number of relays for specific outage capacity. A comparison between decode and forward relaying and amplify and forward relaying shows that decode and forward relaying outperforms amplify and forward relaying for a large number of relays.

• Journal of Communications and Networks
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• v.10 no.2
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• pp.156-162
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• 2008

Cooperative relays can provide spatial diversity and improve performance of wireless communications. In this paper, we study subcarrier power allocation at the relays for orthogonal frequency division multiplexing (OFDM)-based wireless systems. For cooperative relay with amplify-and-forward (AF) and decode-and-forward (DF) algorithms, we investigate the impact of power allocation to the mutual information between the source and destination. From our simulation results on word~error-rate (WER) performance, we find that the DF algorithm with power allocation provides better performance than that of AF algorithm in a single path relay network because the former is able to eliminate channel noise at each relay. For the multiple path relay network, however, the network structure is already resistant to noise and channel distortion, and AF approach is a more attractive choice due to its lower complexity.

• Journal of the Korean Data and Information Science Society
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• v.21 no.3
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• pp.605-619
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• 2010

Caching of frequently accessed data in multi-hop ad hoc environment is a technique that can improve data access performance and availability. Cooperative caching, which allows sharing and coordination of cached data among several clients, can further en-hance the potential of caching techniques. In this paper, we propose a fuzzy cooperative caching scheme in mobile ad hoc networks. The cache management of the proposed caching scheme not only uses adaptively CacheData or CachePath based on data sim-ilarity and data utility, but also uses the replacement manager based on data pro t. Also, the proposed caching scheme uses a prefetch manager. When the TTL of the cached data expires, the prefetch manager evaluates the popularity index of the data. If the popularity index is larger than a threshold, the data is prefetched. Otherwise, its space is released. The performance of the proposed scheme is evaluated analytically and is compared to that of other cooperative caching schemes.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.3
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• pp.117-134
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• 2012

We analyze a systematic relationship between transaction mechanisms and wholesale pricing schemes within a supply-chain with two competing suppliers and a monopolistic retailor. When one of the suppliers changes its transaction mechanism from an independent scheme to a cooperative one, then the wholesale prices of the suppliers become cheaper than before. When one supplier changes its transaction scheme to a cooperative one while the other supplier sticks to the existing independent transaction scheme, we show that the supplier with a cooperative transaction scheme can realize the increased profit via a profit sharing contract with the retailer but the supplier with independent transaction scheme can face the decreased profit. We also show that both suppliers can achieve the higher profits by adopting the cooperative schemes with the retailer.

• International Journal of Contents
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• v.5 no.4
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• pp.69-74
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• 2009

This paper has done a study of Chinese-Korean cooperative multimedia design education. Sino-Korean school of multimedia was set up by Shanghai University of Engineering Science (SUES) and Korea Dongseo University in October 2002. We have created "3.5+0.5 Teaching Model". In this model, Chinese and Korea professors take courses together. Firstly, paper points our the Chinese government policy background of Chinese-Foreign Cooperation in running schools and the development of Chinese-Korean cooperative multimedia design education in SUES. Secondly, by analyzing the multimedia design industry to understand the Chinese multi-media design education. Thirdly, paper made in-depth studies for "3.5+0.5 Teaching Model" so as to draw the experience of successes and problems. Through analysis of "Questionnaires for students' learning and living conditions in Dongseo University in 2009" by spss 16.0, paper made a research of mode of "A semester studying in Korea". Finally, paper points out the development direction of Chinese-Korean cooperative multimedia design.

• Proceedings of the Korean Society of Rheology Conference
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• 2001.09a
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• pp.159.1-159
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• 2001