• Journal of KIISE:Computing Practices and Letters
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• v.11 no.1
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• pp.50-61
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• 2005

To provide adaptively video streaming services on network environment, video transcoding is introduced. The one of transcoding methods is the frame-rate conversion. it needs a re-estimation about a motion vector of the frame to refer a skipping frame. This re-estimation makes higher the computational complexity in video transcoding. To reduce the computational complexity of a motion vector refinement, this paper proposes a region & activity based motion vector composition scheme that refine the moving vector of a skipping frame. This scheme composes each motion vector from the weight based on the activity information of a macroblock and the site of the overlapped area. The experiment result shows that RABVC has a higher PSNR than the value of existing weight-based motion vector selection schemes though the computational complexity of our scheme is similar to that of other schemes.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.493-498
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• 2009

Bluetooth is a popular wireless data transmission method with low power consumption, but it has low data transmission rate. Thus, although many video stream players of a local or network file exist, there have been few players of video stream transmitted via Bluetooth. MPEG-4 AVC/H.264 codec is one of video codecs available with best compression rates for a certain quality, so a H.264 encoder seems to be adequate for video stream to be transmitted via Bluetooth. In this paper, we present a DirectShow filter based player of video stream encoded by H.264 codec, which is transmitted via Bluetooth. Details on the design and implementation of this program are described. Experimental results are shown to demonstrate the validity of the implemented program using various video samples.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.440-448
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• 1999

본 논문은 객체지향형 분산처리 환경 하에서 오디오나 비디오 등과 같은 실시간(real-time) 스트림(stream) 데이타를 처리하는 데 필요한 소프트웨어 기반구조를 설계하고 구현한 내용을 기술한다. 본 논문에서 제시한 DAViS(Distributed Object Framework supporting Audio/Video Streaming)는, 오디오/비디오 데이타의 처리와 관련된 여러 소프트웨어 구성요소들을 분산객체로 추상화하고, 그 객체들간의 제어정보 교환경로와 오디오/비디오 데이타 전송경로를 서로 분리하여 처리한다. 분산응용프로그램 작성자는 DAViS에서 제공하는 서비스들을 이용하여, 기존의 분산프로그래밍 환경이 제공하는 것과 동일한 수준에서 오디오/비디오 데이타에 대한 처리를 표현할 수 있다. DAViS는, 새로운 형식의 오디오/비디오 데이타를 처리하는 부분을 손쉽게 통합하고, 하부 네트워크의 전송기술이나 컴퓨터시스템 관련 기술의 진보를 신속하고 자연스럽게 수용할 수 있도록 하는 유연한 구조를 가지고 있다. Abstract This paper describes the design and implementation of software framework which supports the processing of real-time stream data like audio and video in distributed object-oriented computing environment. DAViS(Distributed Object Framework supporting Audio/Video Streaming), proposed in this paper, abstracts software components concerning the processing of audio/video data as distributed objects and separates the transmission path of data between them from that of control information. Based on DAViS, distributed applications can be written in the same abstract level as is provided by the existing distributed environment in handling audio/video data. DAViS has a flexible internal structure enough to easily incorporate new types of audio/video data and to rapidly accommodate the progress of underlying network and computer system technology with very little modifications.

• Journal of Internet Computing and Services
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• v.8 no.6
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• pp.21-28
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• 2007

Hierarchical Mobile IPv6 improves performance of Mobile IPv6 by managing Binding Update in terms of location, With improved handover delay, realization of delay-sensitive services (e,g, VoIP or video streaming) has become more persuadable, Comparing with Mobile IPv6, however, Hierarchical Mobile IPv6 brings security threats related to Local Binding Update to mobile network, In the RFC 4140, specific methods to authenticate Local Binding Update message are not explicitly presented. It is essential that design secure architecture to address problems related to authenticating Local Binding Update, Many secure suggestions for Local Binding Update, however, concentrate on infrastructure-based solutions such as AAA PKI. These approaches may cause scalability problem when the suggested solutions are applied to real network. Therefore we suggest authentication method that doesn't require infrastructure, In addition to authentication of Local Binding Update, our method also provides mobile node with power saving ability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1369-1376
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WiMedia Distributed-MAC(D-MAC) protocol is adopted for development of a seamless N-Screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU(One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a Dynamic Threshold-based Multicast(DTM) technology is proposed and analyzed. For this technology, a new Hard/Soft Vertical Region(HVR-SVR) based time slot allocation and a multicast resource reservation scheme are combined. From simulation results, proposed DTM scheme expands the number of time slots available for unicast and multicast realtime N-Screen reservations with various service time interval requests. Furthermore, it enhances performances in vewpoints of realtime N-Screen data reservation conflict and throughput.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.75-82
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• 2008

Mobile IP was proposed to overcome identity problem of original IP address system caused by mobility of wireless mobile host. To complete its network handoff procedure, it must receive a mobile advertisement broadcasted by mobile agent. Generally, in a mobile IP system, mean time delay, 500ms, in a network handoff procedure is a critical problem of wireless service such as Voip, multimedia streaming. A caching agent caches a latest mobile advertisement, and replays it by receiving solicitation message from a mobile node finishing link layer detection. But, during the procedure of mobile registration, many packets from service provider to the mobile host would be lost and handoff time delay would be increased. In this thesis, we propose an unproved caching agent technique which can forward data packets while handoff procedure, and CoA pool for fast mobile IP registration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.950-956
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• 2015

In this paper, a WiMedia Distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a ATMT (Asynchronous Traffic Multi-hop Transmission) technology is proposed and analyzed. In this system, a WiMedia ATMT D-MAC bridge transmits control and managing information to various sensors and instruments, from a central integrated ship area network station. For this technology, a time slot allocation scheme for WiMedia asynchronous traffic and a multi-hop resource reservation scheme are combined to evaluate the performance of each scheme. From simulation results, the proposed ATMT scheme enhances performances in viewpoints of N-screen asynchronous data latency and throughput, compared to the conventional WiMedia D-MAC system.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.5
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• pp.44-56
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• 2009

Multimedia streaming service is susceptible to loss and delay of data as it requires high bandwidth and real time processing. Therefore QoS cannot be guaranteed due to data loss caused by heavy network traffic and error of wireless channel. To solve these problems, studies about algorithms which improve the quality of multimedia by serving differently according to the priority of packets in multimedia stream. Two algorithms are proposed in this paper. The first algorithm proposed is WMS-1(Wireless Multimedia Scheduling-1) algorithm which acts like IWFQ when any wireless loss is occurred but assigns channels first in case of urgent situation like when the running time of multimedia runs out. The second algorithm proposed is WMS-2(Wireless Multimedia Scheduling-2) algerithm that assigns priority to multimedia flow and schedules flow that has higher priority according to type of frame first. The comparison with other existing scheduling algorithms shows that multimedia service quality of the proposed algorithm is improved and the larger the queue size of base station is, the better total quality of service and fairness were gained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1055-1061
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• 2008

H.264 is the prominent video coding standard in various applications such as real-time streaming and digital multimedia broadcasting, since it provides enhanced compression performance, error resilience tools, and network adaptation. Compression efficiency of H.264 has been improved, however, it requires more computing and memory access than traditional methods. In this paper we proposed adaptive intra fast algorithm for real-time video surveillance system reducing the encoding complexity of H264/A VC. For this aim, temporal interrelationship between macroblock in the previous and the current frame is used to decide the encoding mode of macroblock fast. As a result, though video quality was deteriorated a little, less than 0.04dB, and bit rate was somewhat increased in suggested method, however, proposed method improved encoding time significantly and, in particular, encoding time of an image with little changes of neighboring background such as surveillance video was more shortened than traditional methods.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.4
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• pp.371-380
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• 2020

Video is principal information that facilitates commander's immediate command decision. Due to fading characteristics of radio link, however, it is difficult to stably transmit video in a multi-hop wireless environment. In this paper, we propose a MANET structure composed of a link adaptive routing protocol and a TDMA MAC protocol to stably transmit video traffic in a ultra-narrowband video streaming network. The routing protocol can adapt to link state change and select a stable route. The TDMA protocol enables collision-free video transmission to a destination using multi-hop dynamic resource allocation. As a result of simulation, the proposed MANET structure shows better video transmission performance than proposed MANET structure without link quality adaption, AODV with CSMA/CA, and OLSR with CSMA/CA structures.