• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.516-525
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• 2012

In this paper, an efficient technique for enhancing the QoS of multimedia service for an WiMedia network applying distributed cooperative medium access (D-MAC) protocol is proposed. D-MAC protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia supports all devices to be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However the WiMedia D-MAC can't prevent reduce the throughput degradation occurred by mobile nodes with low data rate. Therefore, a distributed cooperative MAC protocol for multi-hop UWB network is proposed in this paper. The proposed technique can intelligently select the transmission path with higher data rate to provide real-time multimedia services with minimum delay, thus enhances QoS of multimedia service.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.423-432
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• 2011

In a warehouse, because there exist frequent changes of stock status and the quality of some contents are influenced by the environment such as temperature, fast and accurate management of the warehouse's environment is very important for Warehouse Management Systems (WMS). However, due to the absence of a unified standard for the communication protocol between RFID nodes, the connection between RFID nodes can be broken in case of movement of a RFID reader to a region with a different protocol. Moreover, centralized MAC schemes for RFID communications in previous studies have severe problems. For an example, if a cluster header disappears from the cluster due to the cluster header's movement or bad channel conditions, the RFID member nodes of the cluster waste lots of time and energy to re-elect a new cluster header. Therefore, in this paper, we propose a WiMedia Distributed MAC (D-MAC) scheme for RFID communications and its cooperative relay transmission scheme for WMS applications Simulation results show performance improvement at the RFID node by using the proposed cooperative relay transmission scheme.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.50-57
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• 2006

In Electronic Commerce, the latest most of the personalized recommender systems have applied to the collaborative filtering technique. This method calculates the weight of similarity among users who have a similar preference degree in order to predict and recommend the item which hits to propensity of users. In this case, we commonly use Pearson Correlation Coefficient. However, this method is feasible to calculate a correlation if only there are the items that two users evaluated a preference degree in common. Accordingly, the accuracy of prediction falls. The weight of similarity can affect not only the case which predicts the item which hits to propensity of users, but also the performance of the personalized recommender system. In this study, we verify the improvement of the prediction accuracy through an experiment after observing the rule of the weight of similarity applying Vector similarity, Entropy, Inverse user frequency, and Default voting of Information Retrieval field. The result shows that the method combining the weight of similarity using the Entropy with Default voting got the most efficient performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.235-243
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• 2009

In this paper, we investigate the cognitive and cooperative communication scheme to improve the spectral efficiency in multiuser OFDMA systems using wireless relays. First, we propose the frame structure in which the efficient frequency reuse scheme with the cognitive technique is performed to increase the system throughput. And in the case where the THP (Tomlinson-Harashima preceding) is used for the elimination of interference from the relay, we derive the effective signal to noise ratio of the link largely affected by the channel quantization error. From the system level simulation results, it is shown that the proposed cognitive and cooperative communication scheme increases the overall system performance including the feedback overhead.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.44-50
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• 2010

Wireless sensor network is consist of multiple sensor nodes and performs a shared tasks through the coordination of sensor nodes. Traffic in WSN is categorized as periodical monitoring traffic, event-driven traffic and query-based traffic. Periodic traffic takes significant proportion of the whole traffic processing because multiple sensor nodes generate traffic in a steady interval although the generation frequency of periodic traffic is low. In this paper, we propose a traffic control algorithm of network protocol for periodic traffic in terms of energy efficiency and conduct performance analysis of the algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4A
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• pp.316-323
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• 2009

Power allocation of soft frequency reuse(SFR) to increase cell edge user throughput by reducing inter-cell interference is proposed for coordinated cellular systems. SFR is the effective technique to increase cell edge user throughput, however, it costs the degradation of total system throughput. The cost increases when SFR operated in distributed resource controlled systems fails to be fast adaptive in the change of user distribution. The proposed scheme enables coordinated cells to control transmit power adaptively depending on user distribution so that it minimizes the loss of system throughput introduced from SFR while it guarantees enhancement of cell edge user throughput. Through system level simulation considering neighboring two cells, evaluation result for adaptive power allocation is shown compared with static power allocation.

• Journal of the Korean Society for information Management
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• v.31 no.3
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• pp.133-151
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• 2014

This study was to investigate the concept of ISNI and to find its availability in authority control, realizing importance of ISNI as the bridge identifier including all the information media content industries. ISNI is needed for global and comprehensive name authority control as the bridge identifier for the identification of public identities of parties involved throughout the information media content industries in the creation, production, management and content distribution chains. First of all, it was to inquire ISNI concept, goal, terms and definitions, structure and syntax, allocation of ISNI, administration of the ISNI system, and metadata. Next, it was to suggest the applicability of ISNI in authority control. First, it should be needed to consider in applying ISNI for cooperative authority control. It is possible to interactively use the authority data created in library and other information industries area by constructing KISNI system. Second, it is possible to construct linked data by linking various identifier through ISNI identifier as bridge identifier. Third, it is needed to develop KORMARC for describing ISNI identifier in KORMARC bibliographic and authority record.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.433-440
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• 2005

The sharing of objects for authoring frequently occurs among participating users in a cooperative authoring system where many users can collaborate. Floor control is therefore needed not only for minimizing the race condition during object accesses but also for ensuring the exclusive use of objects. h floor is a temporary access right that is given to a participating user who wants to use a shared object. Although the floor control methods for a single session environment can be found in various literature, those methods for a multi-session environment can hardly be found. In a multi-session environment, an object can be shared by multiple sessions. As a solution to the problems due to object sharing in such an environment, this paper presents a floor control method based on the chair-of-chair guidance. This method is an extension of those based on traditional chair guidance; the chair-of-chair elected among session chairs exists in this method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.553-562
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• 2003

Supporting QoS (Quality of Service) for the multimedia applications becomes an important issue as the demand of multimedia applications increases. Thus, it is necessary for the application layer to have an efficient congestion control algorithm, which can support the multimedia applications' QoS requirements. In this paper, we propose a new application layer congestion control algorithm, called RRC-OTT (Receiver-based Rate Control with One-way Trip Time). RRC-OTT algorithm differs from the previously proposed algorithms in that the receiver takes the responsibility of the network congestion control. Thus, RRC-OTT algorithm can not only precisely estimate the network congestion using OTT (one-way Trip Time), but reduce the work load from the sender (e.g., the web server). Our simulation study shows that RRC-OTT algorithm can maintain the comparable link utilization to the previously proposed algorithms and keep the packet jitter low, which thus can help enhance the quality of multimedia applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.307-309
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• 2016

This paper present about the system for sensing and controlling a wireless power transfer system using bluetooth protocol in robot, healthcare, smart-grid, and autonomous car. Recently a variety of applications using the Internet of Things (Internet of Things) and machine to machine (Machine to Machine) have been raised in many industries. To do this, it requires the fusion technology which is constituted with control, computing and networking. Embedded system is centered existing control system and Cyber Physical System(CPS) is the systems which was converged of a computing technologies using a wired or wireless network. CPS was adopted in the future government-led technology in the United States and Europe and is being pursued in cooperation with institutes, industries, and academia. In this paper, we implement and describe a technique for controlling the system for transmitting power wirelessly by sensing method using the matching of CPS technology concepts.