• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.297-305
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• 2001

Recently advances in high-speed networks and multimedia computer technologies allow new types of multimedia applications to manipulate large volumes of multimedia data. However, in the real time and/or the heterogeneous data transmissions, there are many difficulties such as network transmission delay, the implementation difficulties, and so on. To solve these problems, in this paper, we extend the method of the multimedia service design which is proposed by OMG. To do this, we suggest an efficient real time audio/video stream framework, called Smart Explorer, based un CORBA and JMF Java Media API. And we separate the transmission path of control data from that of media data and use RTP/RTCP protocol for efficient real time audio/video transmission. Also we show the appropriate implementation of the audio/video stream system based on our suggested framework Smart Explorer. In the future, we expect our audio/video stream system to be applied to the real time communication software such as broadcasting, distance learning, and video conferencing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4C
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• pp.326-332
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• 2002

To transfer the large size of data more quickly among cluster nodes, the lightweight messaging scheme has been developed. VIA(Virtual Interface Architecture) allows that user can directly communicate with network devices without any interference of kernel and has become a communication protocol for clusters. But one must spend a lot of time to be skillful with it because of difficulties of programming. Therefore, we propose an easier library called EVIL(Easy-to-use Virtual Interface Library) that developers can easily deal with. We evaluated the performance of EVIL, Native VIA, TCP/IP respectively.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.3
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• pp.67-75
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• 2010

Network reprogramming is a technology that allows several sensor nodes deployed in sensor field to be repaired remotely. Unlike general communication in sensor network where small amount of data is transferred, network reprogramming requires reliable transfer of large amount of data. The existing network reprogramming techniques suffers high cost and large energy consumption to recover data loss in node communication. In this paper, a cluster based network reporgramming scheme is proposed for sensor network. It divides sensor field into several clusters and chooses a cluster header in charge of data relay to minimize duplicated transmission and unnecessary competition. It increases reliability by effective error recovery through status table.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.656-663
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• 2005

This paper presents a multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN (Wireless Personal Area Network). The current MAC protocol of the IEEE 802.15.3 High-rate WPAN is designed for sharing a single channel among DEVs of a piconet; that is, within a single piconet, PNC prevents interference through MAC layer assignment of time slots to other DEVs using time-division multiple access. When the number of DEVs that communicate with each other frequently, is increased in a single WPAN, the size of the superframe becomes inevitably large, and this may result in a significant throughput drop or a failure to provide QoS guarantee. A multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN is proposed to significantly increase the aguegate throughput and more reliably provide the QoS guarantees in a piconet

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.180-182
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• 2002

전력 시장의 자율 경쟁체제가 본격화되면서 기존 공급자 중심의 시장은 급격하게 사용자 중심의 시장으로 재편되어 가고 있다. 기존의 최소한의 '데이터'라는 개념은 최대한의 '정보'라는 개념으로 변화되었다. 정보의 신속하고 효율적인 관리는 변전소 자동화 시스템의 핵심 전략이자 이를 기반으로 한 전력 시스템의 IT화를 가속화시키는 원동력이 되었다. 외국의 경우 1990년대 초에 등장한 UCA2(Utility Communication Architecture)를 기반으로 한 IEC 61850(Communication Networks and systems in substation)이라는 새로운 통신 아키텍처의 도입을 서두르고 있다. IEC 61850은 IEC에서 추진중인 표준화작업의 일환으로 기존의 포인트와 태그(address) 중심의 전력 SCADA 시스템과는 달리 디바이스 및 관련 정보를 데이터 클래스 모델링을 통해 객체화하고 이 표준 객체를 통해 공통의 언어로 통신을 하는 방식으로 wire 중심이 아닌 bus 중심의 통신 방식(Ethernet)을 채용하여 대용량 정보의 실시간 전송 및 이기종간 통신이 가능한 장점을 가지고 있다. 본 논문에서는 IEC 61850을 중심으로 변전소 자동화 시스템 및 전력 시스템의 IT화와 관련된 표준 통신 프로토콜들을 소개하고 전력시스템과 변전소 환경이라는 특수 상황을 고려하여 새롭게 등장한 아키텍처의 특징을 살펴본다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.103-113
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• 2008

Reducing handoff latency is essential in providing seamless multimedia service in Wireless LAN based on the IEEE 802.11 standard. Reducing authentication delay is critical in reducing handoff latency. To this end, several authentication protocols for fBst handoff have been proposed. Mishra et al. used proactive key distribution to improve the authentication delay incurred in the current standard and Park et al. proposed a new authentication protocol based on Blom's key pre-distribution scheme. In this paper, we propose an enhanced authentication protocol based on Bresson et al.'s group key protocol. If a mobile node has previously access the network, our proposed protocol only requires simple hash operations in providing mutual authentication between a mobile node and access points. Our protocol is more efficient than Park et al.'s and Mishra et al.'s technique can be used in our protocol to further enhance our protocol.

• Journal of Game and Entertainment
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• v.2 no.1
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• pp.8-16
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• 2006

The development of multicast communication services in the Internet is expected to lead a stable packet transfer even though On-Line Games generate heavy traffic. The Core Based Tree scheme among many multicast protocols is the most popular and suggested recently. However, CBT exhibits two major deficiencies traffic concentration or poor core placement problem. Thus, measuring the bottleneck link bandwidth along a path is important to understand the performance of multicast. We propose a method in which the core router's state is classified into SS(Steady State), NS(Normal State) and BS(Bottleneck State) according to the estimated link speed rate, and also the changeover of multicast routing scheme for traffic overload. In addition, we introduce Anycast routing tree, an efficient architecture for constructing shard multicast trees.

• Journal of IKEEE
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• v.19 no.3
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• pp.447-454
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• 2015

In this paper, the complexity analysis for implementation of the PM-store is performed in terms of the number of instruction cycles which is executed by CPU in a personal health device(PHD) in order to transfer the large amount of the periodically generated measurement data using the PM-store concept defined in ISO/IEEE 11073 PHD standards. We propose an analytic model that is focused on the number of instruction cycles executed by CPU depending on the PM-store hierarchy.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.351-359
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• 2009

Recently with increase of data in the Internet, platform technologies that can process huge data effectively such as Google platform and Hadoop are regarded as worthy of notice. In this kind of platform, there exist network I/O overheads to send task outputs due to the MapReduce operation which is a programming model to support parallel computation in the large cluster system. In this paper, we suggest applying of TIPC (Transparent Inter-Process Communication) protocol for reducing network I/O overheads and increasing network performance in the distributed computing environments. TIPC has a lightweight protocol stack and it spends relatively less CPU time than TCP because of its simple connection establishment and logical addressing. In this paper, we analyze main features of the Hadoop-based distributed computing system, and we build an experimental model which can be used for experiments to compare the performance of various protocols. In the experimental result, TIPC has a higher bandwidth and lower CPU overheads than other protocols.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.948-955
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• 2019

As interests in 360-degree VR (Virtual Reality) video services enormously grow, compression and streaming technologies for VR video data have been rapidly developed. Quality Emphasized Region (QER) based streaming scheme has been developed as a kind of viewport-adaptive 360-degree video streaming technology for maintaining immersive experience and reducing bandwidth waste. For selecting a QER corresponding to the user's gaze coordinate, QER-based streaming scheme requires the calculation of Quality Emphasis Center (QEC) distance and signaling message delivery for requesting QER switching. QEC distance calculations require high computational complexity because of repeated calculations as many times as the number of QERs. Furthermore, the signaling message interval results in a trade-off relationship between efficient bandwidth usage and flexible QER switching. In this paper, we propose an improved QER selection algorithm based on MMT protocol to solve this problem. The proposed algorithm could achieve computational complexity reduction by using preprocessed QER_ID_MAP. Also, flexible QER switching could be achieved, as well as efficient bandwidth utilization by an adaptive adjustment of the signaling interval.