• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2095-2110
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• 2015

This paper presents a design for a throughput-efficient online relay selection scheme for dual-hop multi-relay cooperative networks. Problems arise with these networks due to unpredictability of the relaying link quality and high time-consumption to probe the dual-hop link. In this paper, we firstly propose a novel probing and relaying protocol, which greatly reduces the overhead of the dual-hop link estimation by leveraging the wireless broadcasting nature of the network. We then formulate an opportunistic relay selection process for the online decision-making, which uses a tradeoff between obtaining more link information to establish better cooperative relaying and minimizing the time cost for dual-hop link estimation to achieve higher throughput. Dynamic programming is used to construct the throughput-optimal control policy for a typically heterogeneous Rayleigh fading environment, and determines which relay to probe and when to transmit the data. Additionally, we extend the main results to mixed Rayleigh/Rician link scenarios, i.e., where one side of the relaying link experiences Rayleigh fading while the other has Rician distribution. Numerical results validate the effectiveness and superiority of our proposed relaying scheme, e.g., it achieves at least 107% throughput gain compared with the state of the art solution.

• Journal of the Korean Society of Earth Science Education
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• v.2 no.1
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• pp.41-47
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• 2009

This study examined the difference for the ability of self-directed learning and information literacy(the ability to use information) between small group-cooperative instruction of ICT practical environment and explanatory instruction using ICT of general classroom in middle school science education. The 138 students(7th grade) participated in this study were classified in two group, experimental group(68) and controlled group(70). Experimental small group consisted of 5-6 students who had different levels and the ability of each the group was equal. The teaching of experimental group was made in the science lab which was equipped with computers to connect super high-speed Internet. The teaching of control group was made in general classroom. Under these two environment, this study was executed during 10 weeks. As the result, Small group-cooperative learning using ICT was more effective in diminishing the gap of information literacy in middle school students. And in the ability of self-directed learning, the small group learning using ICT was also more effective than general classroom instruction.

• Journal of Dairy Science and Biotechnology
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• v.36 no.1
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• pp.39-48
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• 2018

This study examined the immunomodulatory effects of milk fermented with based on the synbiotic interaction between Cudrania tricuspidata leaf extract (CT) and Lactobacillus gasseri 505. Raw 264.7 macrophages were treated with milk (Control), milk supplemented with 0.2% CT (CT-milk), or CT-milk fermented with L. gasseri 505 (FCT). FCT-treated cells showed higher NO production than the other groups. ELISA revealed that FCT produced the highest enhancement of the production of pro-inflammatory cytokines such as $TNF-{\alpha}$, $IFN-{\gamma}$, $IL-1{\beta}$, IL-6, IL-2, IL-12, and IL-10. Furthermore, FCT also increased the gene expression of pro-inflammatory mediators such as iNOS and COX-2 in a concentration-dependent manner. Collectively, these results indicate that the synbiotic interaction between CT and L. gasseri 505 might enhance their immunomodulatory effects of fermented milk.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.3
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• pp.180-187
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• 2014

This paper introduces reliable multicast MAC protocol for cooperative unmanned vehicles. cooperative unmanned vehicles communicate with infrastructure and other unmanned vehicles in order to increase driving safety. They exchange information related to driving and thus it requires real-time and reliable multicast. However, the international vehicular communication standard, IEEE 802.11p WAVE, does not provide a reliable multicast scheme on the MAC layer. To address the problems of reliability, we propose a reliable multicast protocol called WiVCL, which avoids contention and collision. Our evaluation shows that the WiVCL achieves a high degree of reliability and real-time features.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1288-1293
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• 2009

Performing 'Mega Project' in which various stakeholders are involved is difficult to control due to the respective conflicting objectives. Urban regeneration which is being challenged issue in various ways can be defined as the mega project. Since the mega project like urban regeneration a long-continued project and includes a lot of participants whose benefits conflict, cooperation among stakeholders is essential. Moreover, as the project goes, diverse decision making situations which require collaboration happen, and if proper decision making cannot be given at that time, the whole project would have critical effects. Also, since each activity concerns numerous stakeholders, prompt decision making is difficult in the mega project. Therefore, the objective of this study is to support stakeholder's cooperative decision making in order for conducting successful project. For the purpose of the paper, the concept of cooperation in mega project is redefined and a cooperative decision making framework is suggested. Also, the term of governance, which means cooperative mechanism based on the mutual trust, information sharing and partnership, is applied to the newly defined cooperation. The suggested cooperative decision making framework contains the structure of stakeholders in urban regeneration project which enables participants to understand the relationship among bodies and checklists for supporting decision making appropriately. The application of the framework proposed in this research is expected to contribute subjects' suitable decision making by providing proper information in a timely manner.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2636-2656
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• 2013

To improve the cooperative efficiency of node cooperation and multiple access performance for multihop wireless networks, a priority-differentiated cooperative medium access control protocol with contention resolution (CRP-CMAC) is proposed. In the protocol, the helper selection process is divided into the priority differentiation phase and the contention resolution phase for the helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase of the same priority helpers consists of k round contention resolution procedures. The helpers that had sent the first busy tone and are now sending the longest busy tone can continue to the next round, and then the other helpers that sense the busy tone withdraw from the contention. Therefore, it can select the unique best helper from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted to make the high data rate helper with packet to send transmit its data packets to its recipient without reservation. It can significantly decrease the reservation overhead and effectively improve the cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of CRP-CMAC is 74%, 36.1% and 15% higher than those of the 802.11 DCF, CoopMACA and 2rcMAC protocols in a wireless local area network (WLAN) environment, and 82.6%, 37.6% and 46.3% higher in an ad hoc network environment, respectively.

• Korean Journal of Cognitive Science
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• v.11 no.1
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• pp.67-80
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• 2000

Distributed cooperative information system is the one that has various knowledge sources as well as problem solving capabilities to get information in a distributed and heterogeneous data environment. In a distributed cooperative information system. a control mechanism to facilitate the available information is very important. and usually the role of the control mechanism determines the behavior of the total system In this research. we proposed a model of the distributed cooperative information system which is based on the multi-agent paradigm. We also implemented a test system to show l its feasibility. The proposed system makes the knowledge sources into agents and a special agent called 'facilitator' controls the cooperation between the knowledge agents The facilitator uses the knowledge granularity level to determine the sequence of the activation of the agents. In other words. the knowledge source with simple but fast processing mechanism activates first while more sophisticated but slow knowledge sources are activated late. In an environment in which we have several knowledge sources for the same topic. the proposed system will simulate the focusing mechanism of human cognitive process.

• Journal of the Korean earth science society
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• v.24 no.3
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• pp.141-149
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• 2003

This study investigated the effect of gender grouping on cooperative learning on the basis of student achievement and science-teaming attitude. Homogeneous and heterogeneous gender groupings were used in the treatment groups for the learning strategies of earth science. Traditional instruction was performed for the control group. Three classes at a middle school were assigned to the groups. Before the treatment instruction, a questionnaire about science-learning attitude was administered to 144 students, and their scores were utilized as covariate. Then, the same questionnaire was given with a test of science achievement designed in this study. The changes in both achievement and attitude among the three groups were analyzed statistically. Significant differences were not shown in science achievement or in the difference of gender with respect to perceptions about science. There were significant changes between the homogeneous and heterogeneous gender grouping in their attitudes toward science instruction. Here the cooperative learning group, regardless of the gender grouping, tends to exhibit more positive perceptions towards their learning environment than the control group, particularly in female students.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.3
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• pp.137-141
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• 2016

The purpose of this study is to evaluate the effect of PBL program for cooperative practice between western and korean medicine. Third and fourth grade medical and Korean medical school students (experimental group: 16 students, respectively) in the Pusan National University were included in the study. Teaching methods was Problem-Based Learning (PBL) which was consist of 4 western and 4 korean medical students and 2 tutors. Modules have been developed by 8 subject experts or educational experts, who have also participated in the PBL as tutor. The program has been proceeded for 4 weeks, where two face-to-face discussions and self-directed learning were done in each module. In experimental group, students' perceptions about the other medicine were surveyed before and after the program and students' and tutors' satisfaction on the program was investigated. The perception survey was also done in the control group at the beginning of the study. The students who participated in this program had more positive perceptions about the other medicine, compared with control group. There were only significant increases on the items of 'understanding of the other medicine' between before and after the program, where no statistical differences were not observed in 'perception of the other medicine or cooperative practice'. Satisfaction in the program was positive.The PBL program enabled students to understand the other medicine, but it didn't lead changes of their perception. To improve students' perception, the program need to be kept steadily.

• Journal of the Korean earth science society
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• v.25 no.2
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• pp.63-73
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• 2004

This study investigated the effect of cooperative learning on the middle school students’ conceptual change of atmospheric and water cycle and also examined the verbal interaction patterns in a cooperative group. The study also analyzed the relationship between the verbal interaction and students’ conceptual change in the cooperative learning situation. Two classes from a middle school were selected as an experimental group (cooperative learning group, n = 37) and a control group (traditional learning group, n = 37), respectively. The experimental group was taught by STAD cooperative learning model and received collaborative skill training. The results of the study can be summarized as follows: first, there were no significant differences in conceptual change between the two groups. As for the middle-achieving students on the pretest, however, the score of the cooperative learning group was significantly higher than that of the traditional learning group. Secondly, verbal interaction in the cooperative learning situation mainly happened among high- and middle achieving students. In addition, the students who were successful in undergoing conceptual change had more frequent verbal interactions than the students who were not. The study suggests that it is more important to interact between a teacher and students than to interact between the students and students in order to correct students’ misconception.