• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.2
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• pp.147-162
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• 2009

In this paper, we propose a Cooperative Transmission Strategy using Entropy-based Relay Selection in Mobile Ad-hoc Wireless Sensor Networks(MAWSN) with Rayleigh Fading Environments. The main features and contributions of the proposed cooperative transmission strategy are as follows. First, entropy-based relay selection is used to improve data transmission reliability from a source node to a destination node. Second, we present a theoretical analysis model for the proposed cooperative transmission strategy with the outage probability of the end-to-end performance. The performance of our protocol is evaluated using analysis and simulation.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.257-266
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• 2006

The powerful benefits of multi-antenna systems can be obtained by cooperative communications among users in multiple access environments without the need for physical arrays. This paper studies a novel cooperative signaling strategy that achieves high performance and low implementation complexity for synchronous code division multiple access (CDMA) wireless mobile networks. The validity of the proposed strategy under slow flat Rayleigh fading channel plus additive white Gaussian noise (AWGN) is verified through closed-form error probability expressions and MonteCarlo simulations. A variety of analytical results reveal that the new cooperative strategy significantly outperforms direct transmission subject to the same spectral efficiency and transmit power constraint.

• Journal of Technology Innovation
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• v.3 no.1
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• pp.1-34
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• 1995

Since 1982, the government of Korea has actively promoted vertical cooperative R&D programs between government-sponsored research institutes (GRIs) and private firms. A number of firms participated in the programs because cooperative R&D could lower the risk and could contribute to rapid commercialization of many technologies. This paper examines the effectiveness of vertical cooperative R&D projects by the modes of cooperation between GRIs and industrial firms, and analyzes the performance of participating firms' technology sourcing strategies for commercial utilization of cooperative R&D results at the project performed from 1982 to 1989 under the Government-Industry Cooperative R&D Program sponsored by the Ministry of Science and Technology(MOST) in Korea. The cooperative R&D projects are classified into 4 groups by two criteria, i.e., the level of participation of firms, and the breadth of cooperation. The findings suggest that firms should actively participate in cooperative R&D projects. In addition, in order to enhance commercial success, cooperation between GRIs and industrial firms should not be limited to R&D stage only. The breadth of cooperation should be extended to commercialization stage. Small- and medium-sized firms participating in vertical cooperative R&D projects in Korea usually lack internal technological capabilities that are needed to commercialize the results of cooperative R&D. Three different technology sourcing strategies - exclusive cooperative R&D strategy, in-house development augmented cooperative R&D strategy, and licensing-in supplemented cooperative R&D strategy - are empirically derived through cluster analysis of the relative usage rates cooperative R&D and of other supplementary technology acquisition methods. The findings suggest that the firms participating in vertical cooperative R&D projects should try to utilize other supplementary technology acquisition methods in order to achieve commercial utilization of the vertical cooperative R&D results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.106-112
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• 2007

A new space-time cooperative communication relaying strategy with assistant or management terminals is proposed in multi-hop wireless communication systems. More than one relaying terminals are included in one cooperative group to share the state information such as frame error rate and channel information. Among the cooperative group, the best ones are selected to send bit information using space-time codes. An implementation for the proposed scheme is also presented using a TDMA cooperative protocol. Receive signal to transmit signal ratio($E_r/E_s$) and computer simulation show the strategy outperform the conventional cooperative system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.109-114
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• 2007

A new space-time cooperative communication relaying strategy with assistant or management terminals is proposed in multi-hop wireless communication systems. More than one relaying terminals are included in one cooperative group to share the state information such as frame error rate and channel information. Among the cooperative group, the best ones are selected to send bit information using space-time codes. An implementation for the proposed scheme is also presented using a TDMA cooperative protocol. Receive signal to transmit signal ratio($E_r/E_s$) and computer simulation show the strategy outperform the conventional cooperative system.

• Journal of The Korean Association For Science Education
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• v.19 no.4
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• pp.635-644
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• 1999

The effect of cooperative learning in a heuristic approach (four stage-problem solving strategy) that also emphasized molecular level representation was studied. Three high school classes (N=130) were randomly assigned to St group (using strategy individually), St-Co group (using strategy in cooperative group), and control group. After instruction, students' multiple-choice problem solving ability, strategy performing ability, and the perception of involvement were compared. Students' preferred instruction type was also examined. Although multiple-choice problem solving ability were not different significantly, a significant interaction between the treatment and the previous achievement level was found in strategy performing ability. Analysis of simple effects indicated that the medium-level students in the St group performed better than those in the St-Co group. In the perception questionnaire of involvement. however, the scores of the St group were significantly lower than those of the control group. The instruction type that students most preferred was also St-Co.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.65-71
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• 2009

In this paper a new space-time diversity relaying strategy using cooperative communication technique is proposed. More than one relaying terminals are included in one cooperative group to share their state information, such as frame error rate and channel state information. The best terminals are selected to send bit information using space-time diversity relay system. An implementation for the proposed scheme is also presented using the TDMA cooperative protocol. The resulting receive signal to transmit signal ratio and computer simulation demonstrate that the proposed strategy outperforms the conventional cooperative system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.28-35
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• 2011

Cooperative ARQ scheme is effective for better QoS guarantee for the next generation mobile communication systems where multimedia data transmission highly increases. In this paper, we propose a cooperative ARQ strategy in ad hoc cognitive relays for mobile multimedia communication for supporting instantaneous cooperation in MANET environment. In the proposed strategy, to support real time, delay-sensitive services, whenever a frame is transmitted from the source, each relay actively senses the SINR of the signal transmitted from the source, and determine whether to propose retransmission or not before the destination transmits feedback signal. To minimize the false retransmission decision or needless retransmission, we propose an adaptive sensing threshold optimization algorithm to maintain suboptimal sensing thresholds for each relay. By computer simulation, it is shown that the proposed cooperative ARQ retransmission scheme outperforms the conventional schemes with respect to frame transmission delay and frame loss probability in real time multimedia data transmission system.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.7
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• pp.591-597
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• 2001

In this paper, we propose a method of cooperative control (T-cell modeling) and selection of group behavior strategy (B-cell modeling) based on immune system in distributed autonomous robotic system (DARS). Immune system is living body's self-protection and self-maintenance system. These features can be applied to decision making of optimal swarm behavior in dynamically changing environment. For applying immune system to DARS, a robot is regarded as a B-cell, each environmental condition as an antigen, a behavior strategy as an antibody and control parameter as a T-cell respectively. The executing process of proposed method is as follows. When the environmental condition changes, a robot selects an appropriate behavior strategy. And its behavior strategy is stimulated and suppressed by other robot using communication. Finally much stimulated strategy is adopted as a swarm behavior strategy. This control school is based on clonal selection and idiotopic network hypothesis. And it is used for decision making of optimal swarm strategy. By T-cell modeling, adaptation ability of robot is enhanced in dynamic environments.

• East Asian Journal of Business Economics (EAJBE)
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• v.7 no.2
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• pp.1-9
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• 2019

Purpose - This study aims to examine whether key differences in characteristics of unions have significant implications for absenteeism. To uncover what characteristics of union made workers make decisions to be absent, this study used such key dimensions of unionism as democracy, cooperative strategy of a union, and d density rate. Research design and methodology - The research model of this study is that absenteeism has positive relations with union's democracy and density. But it has negative relations with union cooperative strategy. This study was conducted by survey method on 333local unionized business entities of metal industry in South Korea. Results - The result shows that significant and positive relationship between unions with high density rates, democracy and absenteeism which is in line with the argument of the previous studies. Different from the expectation, the hypotheses 2, it has been shown that there is positive relation between cooperative strategy of union and the decision of workers to be absent. Conclusions - Employers with unions with high density rates could not fully exercise disciplinary power against those workers absent at workplace since a strong union shields them effectively from punishments by employers.