• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1426-1434
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• 2009

RFID/USN is considered as a key convergence technology in future ubiquitous network. In RFID/USN, the power saving issue receives a great attention due to limited battery lifetime of sensor node. In this paper, we propose a new power saving algorithm, which takes advantage of long-term sleep period. To provide a full network connectivity and balance the battery consumption among sensor nodes, the proposed algorithm intelligently selects the long-term sleep sensor nodes. With mathematical analysis and simulations, we prove that the proposed algorithm can significantly reduce the power consumption of sensor nodes as compared to existing algorithms.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.95-106
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• 2013

The Electronic Times, starting in 1982 as a weekly newspaper, has become an influential daily newspaper specializing in Information Technology(IT) since the mid 1990s in Korea. Particularly, it has shown significant and impressive financial achievements in the past thirty years since it was established. Also, it has contributed to the development in the field of IT journalism as well as the popularization of Information Technology. The primary purpose of this study is to provide useful lessons and implications to those who are interested in the evolution of The Electronic Times by investigating the financial performance of The Electronic Times and its contributions to the popularization of IT in our society.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.731-738
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• 2017

In this paper, we proposed a modified ML detector for generalized spatial modulation which is a method among Multiple-input Multiple-output. This proposed method detects signal applying modified channel statement information based on priority. Complexity in conventional methods increases as increasing the number of active antennas. To solve this problem, we proposed a new ML method using static channel information decided by the number of transmit antennas and the number of receive antennas. This method detects active antennas one by one through priority. The proposed method has proved benefit on complexity compared with conventional method through simulations. When the number of transmit antennas is equal to 10, there is approximately 45% complexity reduction.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.325-332
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• 2012

VANET(Vehicular Ad-hoc Network), which is a technology to create a network among vehicles, decides the route to the destination using information of neighbors within the transmission range as transmission nodes. The existing routing protocol which uses geographical information can cause delay and disconnection of the network when the density of nodes is not high enough to communicate because it only considers the distance of the relay nodes or destination nodes from the source nodes. To solve the problem, this dissertation suggests a routing algorithm based on zones for stable communications among vehicles in the environment of VANET. I minimize the packet loss rate by dividing the city environment into zones and taking into account not only the distance of the destination but also the density of vehicles to choose the best communications environment. This results in a better performance than the established research when the performance evaluation is implemented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1817-1836
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• 2020

Network convergence is considered as one of the key solutions to the problem of achieving future high-capacity and reliable communications. This approach overcomes the limitations of separate wireless technologies. Efficient interface selection is one of the most important issues in convergence networks. This paper solves the problem faced by users of selecting the most appropriate interface in the heterogeneous radio-access network (RAN) environment. Our proposed scheme combines a hierarchical evaluation of networks and game theory to solve the network-selection problem. Instead, of considering a fixed weight system while ranking the networks, the proposed scheme considers the service requirements, as well as static and dynamic network attributes. The best network is selected for a particular service request. To establish a hierarchy among the network-evaluation criteria for service requests, an analytical hierarchy process (AHP) is used. To determine the optimum network selection, the network hierarchy is combined with game theory. AHP attains the network hierarchy. The weights of different access networks for a service are calculated. It is performed by combining AHP scores considering user's experienced static network attributes and dynamic radio parameters. This paper provides a strategic game. In this game, the network scores of service requests for various RANs and the user's willingness to pay for these services are used to model a network-versus-user game. The Nash equilibria signify those access networks that are chosen by individual user and result maximum payoff. The examples for the interface selection illustrate the effectiveness of the proposed scheme.

• Journal of Convergence for Information Technology
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• v.9 no.2
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• pp.165-171
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• 2019

The purpose of this study was to analyse a causal relationship between collective emotion and behavior to sport issues in SNS. For the purpose, 5 sports issues with obvious collective behavior and 5 concerned articles in typical portal sites were selected. From those, each 100 comments with highest recommendation and 5 obvious actions made by the crowd were sampled as the analysis subjects. The results of statistical analyses on collective emotion and behavior materials were as follows. First, collective emotions showed differences by the sports issues. Second, there was a significant causal relationship between collective emotion and behavior in SNS. This study could receive a favorable evaluation due to the statistical analysis on a causal relationship between collective emotion and behavior.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.403-412
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• 2017

With the introduction of BIM and ICT technology, 'Cloud-based collaborative design support system' has been actively researched and new user interface is needed to support it. When developing the user interface, scenario - based design method is selected which based on the actual usage scenarios to anticipate the usage situation and reflect the user's requirements. However, since the existing scenario-based design technique is an inductive method, it is difficult to cover the usage situation of all users when creating the usage scenario. For this reason, there is a need for a new scenario creation method that can systematically create and modify scenarios instead of inductive methods. This study proposes a 'Multi-scenario-based design method' that complemented the existing method and verify its usability by applying it to the user interface development process of 'Cloud-based collaborative design support system'.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.398-407
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• 2010

Due to increase of user requirement for various traffics and the advance of network technology, each distinct network has converge into FMC(Fixed Mobile Convergence) networks. However, we need to research the performance analysis of VoIP(Voice over Internet Protocol) in the FMC network to provide QoE for the voice user of FMC network. Therefore, this paper introduces the scenario which is the situation of voice quality degradation when a user uses VoIP to communicate with other users in the FMC network. Especially, this paper presents scenario in terms of the component of the network and finds the improvement point of voice quality. In the simulation results, three improvement points of voice quality are found as following: voice quality degradation by packet loss in the physical layer of the HSDPA network, by utilizing GGSN without QoS parameter mapping mechanism which is gateway between 3GPP and IP backbone, and by using non-QoS AP in the WLAN network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1914-1924
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• 2016

In this paper, considering virtualized Evolved Packet Core(vEPC) network for 5G mobile network, we propose architecture for supporting Service Function Chaining(SFC) in 5G mobile network. Using SFC in 5G network, dynamic path configuration and providing network services based on subscriber and traffic information. SFC technology provides logical ordered set of network functions and delivers packet through providing logical path over the physical network. Based on the perspective of 5G core network in distributed manner, we design hierarchical SFC architecture to manage SFC for global path including vEPC and SGi-LAN network, and internal path between virtualized network functions in each cloud. In this paper, we define architecture and call flow for establishing data path using SFC. Finally, we design testbed architecture for real implementation based on open source software.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.268-274
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• 2011

Recently, we could witness research works on the development of mobile harbor. In line with the implementation of the physical entity for the mobile harbor system, there exists a need for the development of the service management system for the mobile harbor. In this work we propose a framework for the mobile harbor service management system. To that purpose, we first define the principle for the operation of the mobile harbor service management system. Also we develop the mobile harbor service management system by simulation. Finally, we illustrate the implication of the research by experiments.