• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.626-636
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• 2009

In Mobile IP-enabled wireless LAN (WLAN), packet flows are corrupted due to the handoff of a mobile node (MN) at the link and network layers, which results in burst packet losses and can cause temporary buffer underflow in a streaming client at the MN. This transient behavior hurts time-sensitive streaming media applications severely. Among many suggestions to address this handoff problem, few studies are concerned with empirical issues regarding the practical validation of handoff options on the time-sensitive streaming media applications. In this paper, targeting seamless streaming over Mobile IP-enabled WLAN, we introduce a seamless media streaming framework that estimates accurate pre-buffering level to compensate the handoff latency. In addition, we propose a link-layer (L2) assisted seamless media streaming system as a preliminary version of this framework. The proposed system is designed to reduce the handoff latency and to overcome the playback disruption from an implementation viewpoint. A packet buffering and forwarding mechanism with L2 trigger is implemented to reduce the handoff latency and to eliminate burst packet losses generated during the handoff. A pre-buffering adjustment is also performed to compensate the handoff latency. The experimental results show that the proposed approach eliminates packet losses during the handoff and thus verify the feasibility of seamless media streaming over Mobile IP-enabled WLAN.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.240-246
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• 2008

This paper propose a method to enhance the performance of digital contents streaming services with the improve DRM system by maximizing the distribute computing performance and minimizing the overheads of security threatens caused by increasing users and sharing contents in P2P environments. By improving authentication protocols and license protocols to perform decryption and execution simultaneously by only download of the license, streaming services are more enhanced rather than existing DRM systems. For evaluate the performance, this paper compared execution time of existing DRM systems which decrypt the encrypted data file before execute with improved DRM system which execute and decrypt the encrypted data file simultaneously. In experiment, improved DRM system can maintain steady bandwidth and reduce the execution time in compare to existing DRM systems.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.87-90
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• 2015

MPEG-2 TS(Transport Stream)는 DTV(Digital Television), IPTV(Internet Protocol Television), DMB(Digital Multimedia Broadcasting) 등 디지털 방송 분야에서 압축된 오디오 및 비디오 데이터를 다중화하는 데에 전 세계적으로 널리 사용되고 있다. MPEG-2 TS 표준이 제정된 것은 1990년대 초반으로서 20여 년이 지난 오늘날의 방송과 통신 환경에 적합하지 않은 부분이 많이 포함되어 있다. 이러한 상황을 고려하여, MPEG(Moving Picture Experts Group)에서는 2014년에 MPEG-2 TS를 대체하고자 차세대 멀티미디어 전송 표준으로서 MMT(MPEG Media Transport)를 표준화하였다. 특히 네트워크 환경의 발전에 따라, MMT 표준은 IP 친화적이고 여러 가지 다른 종류의 네트워크를 병용한 멀티미디어 전달이 쉽도록 설계되었다. 본 논문에서는 실시간 방송에 의해 수신되는 MPEG-2 TS로부터 실시간으로 MMTP(MMT Protocol) 스트림을 생성하여 UDP/IP로 유무선 인터넷을 통해 멀티미디어 스트리밍 서비스를 제공하는 시스템을 구현하였다. 이를 위해 MPEG-2 TS 실시간 변환 기능을 갖춘 MMT 스트리밍 서버와 이로부터 서비스를 받을 수 있는 MMT 클라이언트를 구현하고 그 동작을 실험을 통해 검증하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.23-26
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• 2019

사물인터넷(IoT)은 지금의 우리가 살고 일하는 모든 방식을 변화시키고 있다. IoT를 통해 데이터를 생성하고 저장하고 연결된 장치와 상호작용하여 비즈니스는 물론 우리의 일상 생활을 개선하고 있는 것이다. 무수히 많은 센서들이 연결된 세상은 센서들에 의해 그 어느 때보다 거대한 양의 데이터들을 생산하고 있다. JSON, XML 같은 트리 구조의 데이터 타입은 대량 데이터 저장 전송 교환 등에 주요하게 사용되는데 이는 트리 구조가 이형 데이터 간의 유연한 정보 전송과 교환을 가능하게 하기 때문이다. 반면에, 효용성 높은 정보나 감추어져 있는 정보들을 트리 구조의 대량 데이터들로부터 추출하는 것은 일반 데이터 구조에 비해 훨씬 어려우며 더 난해한 문제들을 발생시킨다. 본 논문에서는 트리 구조의 대량 스트리밍 데이터로부터 가중치가 부여된 주요한 부정 패턴들을 추출하기 위한 방법을 공식화한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2323-2329
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• 2013

Web-services employ an XML to represent data and an XML parser is needed to use data. The DOM(Document Object Model) is widely used to parse an XML, but it is not suitable for any systems with limited resources because it requires a preprocessing to create the DOM and additional memory space. In this paper, we propose the StreXTree(Streaming XML Tree) with failure transitions and without any preprocessing tasks in order to improve the system performance. Compared to other works, our StreXTree parser achieves 2.39x and 3.02x improvement in system performance in Search and RBStreX, respectively. In addition, our StreXTree parser supports Well-Formed checking to verify the syntax and structure of XML.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4B
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• pp.227-233
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• 2007

According to the recent development of network technology, the demands of users are diversified and the needs of multimedia traffic are increasing. In general, UDP(User Datagram Protocol) traffic is used to transport multimedia data, which satisfied the real-time and isochronous characteristics. UDP traffic competes with TCP traffic and incur the network congestion. However, TCP traffic performs network congestion control but does not consider the receiver's status. Thus, it is not appropriate in case of streaming services. In this paper, we solve a fairness problems and proposed a network algorithm based on RTP/RTCP(Real-time Transport Protocol/Realtime Transport Control Protocol) in view of receiver status. The POBA(Priority Ordered Buffer Algorithm), which applies priorities in the receiver's buffer and networks, shows that it provides the appropriate environment for streaming services in view of packet loss ratio and buffer utilization of receiver's buffer compared with the previous method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1469-1483
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• 2004

We propose a packet scheduling algorithms for streaming media. We assume that the receiver periodically reports back the channel throughput. From the original video data, the importance level of a video packet is determined by its relative position within its group of pictures, taking into account the motion-texture discrimination and temporal scalability. Thus, we generate a number of nested substreams. Using feedback information from the receiver and statistical characteristics of the video, we model the streaming system as a queueing system, compute the run-time decoding failure probability of a Same in each substream based on effective bandwidth approach, and determine the optimum substream to be sent at that moment in time. Since the optimum substream is updated periodically, the resulting sending order is different from the original playback order. From experiments with real video data, we show that our proposed scheduling scheme outperforms the conventional sequential sending scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1300-1305
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• 2020

Due to the simplicity of communication structure using RS-232 and RS-422, the majority ships have still adapted on these communication interfaces and have constructed their own communication network in the ship. NMEA-0183 is the one of standards for BNWAS(Bridge Navigational Watch Alarm System) and currently being used in many countries. BNWAS utilises diverse sensor devices, GPS, AIS and so on for monitoring the status of ships and their deployments and environmental information(temperature, humidity, wind speed/direction, water temperature/current etc…). This paper proposes the use of any image sensors in NMEA-0183 environment and verifies possibility with certain video qualities through the experiment results. Furthermore the paper gathers videos and monitors the change of their qualities depending on the number of NMEA messages on RS-232 communication link. Finally we make conclusion that our proposal is sufficiently appropriate for ship monitoring system in the NMEA-0183.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.163-163
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• 2004

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1086-1096
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• 2004

In case of a multimedia application which deals with streaming data, in terms of cache management, cache loses its efficiency due to weak temporal locality of the data. This means that when data have been brought into cache, much of the data are supposed to be replaced without being accessed again during its service. However, there is a good chance that such multimedia data has a commanding locality in it. In this paper, to take advantage of the memory reference regularity which typically innates even in the multimedia data showing up its weak temporal locality, a method is suggested. The suggested method with the feature of dynamic regular-stride reference prefetching can identify for 2-dimensional array format(block pattern). The suggested method is named as block-reference-prediction-technique (BRPT) since it identifies a block pattern and place an address to be prefetched by the regulation of the block format. BRPT proved to be reassuring to reduce memory reference time significantly for applications having abundant block patterns although new rule has complicated the prefetching system even further.