• Electronics and Telecommunications Trends
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• v.35 no.6
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• pp.137-149
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• 2020

Several multi-agent reinforcement learning (MARL) algorithms have achieved overwhelming results in recent years. They have demonstrated their potential in solving complex problems in the field of real-time strategy online games, robotics, and autonomous vehicles. However these algorithms face many challenges when dealing with massive problem spaces in sparse reward environments. Based on the centralized training and decentralized execution (CTDE) architecture, the MARL algorithms discussed in the literature aim to solve the current challenges by formulating novel concepts of inter-agent modeling, credit assignment, multiagent communication, and the exploration-exploitation dilemma. The fundamental objective of this paper is to deliver a comprehensive survey of existing MARL algorithms based on the problem statements rather than on the technologies. We also discuss several experimental frameworks to provide insight into the use of these algorithms and to motivate some promising directions for future research.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.956-963
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• 2008

In a multi-hop wireless ad hoc network broadcasting is an elementary operation to support route discovery, address resolution and other application tasks. Broadcasting by flooding may cause serious redundancy, contention, and collision in the network which is referred to as the broadcast storm problem. Many broadcasting schemes have been proposed to give better performance than simple flooding in wireless ad hoc network. How to decide whether re-broadcast or not also poses a dilemma between reachability and efficiency under different host densities. In this paper, we propose enhanced broadcasting schemes, which can reduce re-broadcast packets without loss of reachability. Simulation results show that proposed schemes can offer better reachability as well as efficiency as compared to other previous schemes.

• Journal of Digital Convergence
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• v.18 no.1
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• pp.219-229
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• 2020

The purpose of this study was to develop a short biomedical ethics tool for healthcare workers, compare it with pre-existing tool, and increase reliability. Data were collected from 211 healthcare workers working in G-do. Exploratory factor analysis was carried out using Varimax rotation extraction method in IBM SPSS WIN/21.0. Convergent validity of the tool was verified by regression and correlation analysis with original tool score. Reliability was verified by calculating intraclass correlation coefficient and internal consistency coefficient. The short, reduced 21 questions tool reflected 84% of pre-existing tool's biomedical ethics. Its reliability was higher than the 29 question tool for nursing students, but there were differences in the components of subdomains and reliability coefficient. Additional development of questions through qualitative research and interviews are needed to increase reliability of the subdomains. Measurement of biomedical ethics dilemma with the tool that has validity and reliability is needed, followed by replication studies.