• Title/Summary/Keyword: 네트워크 미디어

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An Improved Way of Remote Storage Service based on iSCSI for Mobile Device using Intermediate Server (모바일 디바이스를 위한 iSCSI 기반의 원격 스토리지 서비스에서 중간 서버를 이용한 성능 개선 방안)

  • Kim Daegeun;Park Myong-Soon
    • The KIPS Transactions:PartC
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    • v.11C no.6 s.95
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    • pp.843-850
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    • 2004
  • As mobile devices prevail, requests for various services using mobile devices have increased. Requests for application services that require large data space such as multimedia, game and database [1] specifically have greatly increased. However, mobile appliances have difficulty in applying various services like a wire environment, because the storage capacity of one is not enough. Therefore, research (5) which provides remote storage service for mobile appliances using iSCSI is being conducted to overcome storage space limitations in mobile appliances. But, when iSCSI is applied to mobile appliances, iSCSI I/O performance drops rapidly if a iSCSI client moves from the server to a far away position. In the case of write operation, $28\%$ reduction of I/O performance occurred when the latency of network is 64ms. This is because the iSCSI has a structural quality that is very .sensitive to delay time. In this paper, we will introduce an intermediate target server and localize iSCSI target to improve the shortcomings of iSCSI performance dropping sharply as latency increases when mobile appliances recede from a storage server.

Investigations on Techniques and Applications of Text Analytics (텍스트 분석 기술 및 활용 동향)

  • Kim, Namgyu;Lee, Donghoon;Choi, Hochang;Wong, William Xiu Shun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.2
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    • pp.471-492
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    • 2017
  • The demand and interest in big data analytics are increasing rapidly. The concepts around big data include not only existing structured data, but also various kinds of unstructured data such as text, images, videos, and logs. Among the various types of unstructured data, text data have gained particular attention because it is the most representative method to describe and deliver information. Text analysis is generally performed in the following order: document collection, parsing and filtering, structuring, frequency analysis, and similarity analysis. The results of the analysis can be displayed through word cloud, word network, topic modeling, document classification, and semantic analysis. Notably, there is an increasing demand to identify trending topics from the rapidly increasing text data generated through various social media. Thus, research on and applications of topic modeling have been actively carried out in various fields since topic modeling is able to extract the core topics from a huge amount of unstructured text documents and provide the document groups for each different topic. In this paper, we review the major techniques and research trends of text analysis. Further, we also introduce some cases of applications that solve the problems in various fields by using topic modeling.

Transform domain Wyner-Ziv video coding with successively improving side information based on decoding reliability (복호 신뢰도에 기반하여 점진적으로 보조정보를 향상시키는 변환영역 Wyner-Ziv 부호화 방법)

  • Ko, Bong-Hyuck;Shim, Hiuk-Jae;Jeon, Byeung-Woo
    • Journal of Broadcast Engineering
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    • v.13 no.6
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    • pp.892-904
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    • 2008
  • As a video encoding in resource constrained environments such as sensor networks has become an important issue, DVC(Distributed Video Coding) has been intensively investigated as a solution for light weighted video encoding problem. Known as one of the representative schemes of DVC, the Wyner-Ziv coding generates side information of current frame only at decoder, using correlation among frames, and reconstructs video through noise elimination on the side information using channel code. Accordingly, the better quality of side information brings less channel noise, thus attains better coding performance of the Wyner-Ziv coder. However, since it is hard for decoder to generate an accurate side information without any information of original frame, a method to successively improve side information using successively decoded original frame, based on decoding reliability, was previously developed. However, to improve side information from decoding results, not only an error rate of the decoding result as a reliability, but also the amount of reliable information from the decoding result is important. Therefore, we propose TDWZ(Transform-domain Wyner-Ziv coding) with successively improving side information based on decoding reliability considering not only an error rate but also the amount of reliable information of the decoding results. Our experiment shows the proposed method gains average PSNR up to 1.7 dB over the previous TDWZ, that is without successive side information improvement.

Implementation of a QoS routing path control based on KREONET OpenFlow Network Test-bed (KREONET OpenFlow 네트워크 테스트베드 기반의 QoS 라우팅 경로 제어 구현)

  • Kim, Seung-Ju;Min, Seok-Hong;Kim, Byung-Chul;Lee, Jae-Yong;Hong, Won-Taek
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.48 no.9
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    • pp.35-46
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    • 2011
  • Future Internet should support more efficient mobility management, flexible traffic engineering and various emerging new services. So, lots of traffic engineering techniques have been suggested and developed, but it's impossible to apply them on the current running commercial Internet. To overcome this problem, OpenFlow protocol was proposed as a technique to control network equipments using network controller with various networking applications. It is a software defined network, so researchers can verify their own traffic engineering techniques by applying them on the controller. In addition, for high-speed packet processing in the OpenFlow network, programmable NetFPGA card with four 1G-interfaces and commercial Procurve OpenFlow switches can be used. In this paper, we implement an OpenFlow test-bed using hardware-accelerated NetFPGA cards and Procurve switches on the KREONET, and implement CSPF (Constraint-based Shortest Path First) algorithm, which is one of popular QoS routing algorithms, and apply it on the large-scale testbed to verify performance and efficiency of multimedia traffic engineering scheme in Future Internet.

An Efficient Video Management Technique using Forward Timeline on Multimedia Local Server (전방향 시간 경계선을 활용한 멀티미디어 지역 서버에서의 효율적인 동영상 관리 기법)

  • Lee, Jun-Pyo;Woo, Soon
    • Journal of the Korea Society of Computer and Information
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    • v.16 no.10
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    • pp.147-153
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    • 2011
  • In this paper, we present a new video management technique using forward timeline to efficiently store and delete the videos on a local server. The proposed method is based on capturing the changing preference of the videos according to recentness, frequency, and playback length of the requested videos. For this purpose, we utilize the forward timeline which represents the time area within a number of predefined intervals. The local server periodically measures time popularity and request segment of all videos. Based on the measured data, time popularity and request segment, the local server calculates the mean time popularity and mean request segment of a video using forward timeline. Using mean time popularity and mean request segment of video, we estimate the ranking and allocated storage space of a video. The ranking represents the priority of deletion when the storage area of local server is running out of space and the allocated storage space means the maximum size of storage space to be allocated to a video. In addition, we propose an efficient storage space partitioning technique in order to stably store videos and present a time based free-up storage space technique using the expected variation of video data in order for avoiding the overflow on a local server in advance. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, our video management technique for local server provides the lowest user start-up latency and the highest bandwidth saving significantly.

Threshold Level Setting of a Receiver in Optical Subscriber Network with Manchester Coded Downstream and NRZ Upstream Re-modulation for the Improvement of Upstream Data Ratios (맨체스터 부호로 코딩된 하향신호의 재변조를 이용한 광가입자 망에서 상향속도개선을 위한 임계치의 설정)

  • Park, Sang-Jo
    • Journal of the Korea Society of Computer and Information
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    • v.16 no.12
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    • pp.175-185
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    • 2011
  • The threshold level of a receiver is analyzed for the simplification of system and the improvement of upstream data ratios in optical subscriber network of which the upstream date rate and the optical transmitted power are changed to meet the requested BER (Bit Error Rate) defined per interactive multimedia services. In asynchronous optical subscriber network of which the upstream to downstream data ratios are 1:1/2, 1:1/4, 1:1/8 and 1:1/16 with manchester coded downstream and NRZ (Non Return to Zero) downstream re-modulation, the BER performance is theoretically analyzed and it is performed by simulation with MATLAB according to the four types of downstream data for four models. The results have shown that in the cases which the upstream to downstream data ratios are 1:1/4, 1:1/8 and 1:1/16 the conventional receiver with threshold level of 1/2 can be applied regardless of average received optical powers and the BER is not much deteriorated compared with using the optimal threshold level. In the case that the upstream to downstream data ratio is 1:1/2 the threshold level in an optical receiver could be fixed at 1/3 and the BER is not much deteriorated compared with using the optimal threshold level as the average received optical power increases.

Measurement and Analysis of Performance to Transfer Data in a Wireless-Cum-Wired Intra-Network (유무선 통합 인트라넷 환경에서 데이터 전송 성능 측정 및 분석)

  • Hur Hye-Sun;Hong Youn-Sik;Woo Yo-Seop
    • Journal of Internet Computing and Services
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    • v.5 no.3
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    • pp.99-108
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    • 2004
  • We have designed and implemented a Voice Messenger System(VMS) for sending and receiving voice data in order to measure and analyze the performance of a multimedia data transfer system using PDAs(Personal Digital Assistants) in a fast wireless LAN environment. The VMS has been configured as an infrastructure network by integrating a wireless intra-network based on IEEE 802,11 b standard with a wired network based on Ethernet. A sending time, a receiving time and a round-trip time(RTT) have been measured by varying its pecket size from 256 to 6656 bytes, Besides, we have performed the experiments to see which NIC is more stable between CF and PCMCIA type in such a wireless LAN environment, The results of such experiments show that the NIC with PCMClA type is better than that with CF type from the points of both efficiency and stability. The performance of a notebook computer with the attachment of a wireless NIC that is used as a VMS client is almost constant by varying its packet size when transferring voice data. However, with PDA client, in the case of receiving packets from the VMS server, the performance is the best when the pecket size is 6656 bytes, In addition, in the case of sending packets from PDA client to the VMS server, the performance is the best when the packet size is 4096 bytes. Even with the same pecket size, the time of receiving packets from the VMS server to PDA is longer than the time of sending packets from PDA to the VMS Server, Thus, we conclude that when PDA is used as a client by applying different pecket size when sending and receiving packets should be achieved a better performance over a wireless LAN environment.

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An Efficient P2P Based Proxy Patching Scheme for Large Scale VOD Systems (대규모 VOD 시스템을 위한 효율적인 P2P 기반의 프록시 패칭 기법)

  • Kwon, Chun-Ja;Choi, Hwang-Kyu
    • The KIPS Transactions:PartA
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    • v.12A no.5 s.95
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    • pp.341-354
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    • 2005
  • The main bottleneck for large scale VOD systems is bandwidth of storage or network I/O due to the large number of client requests simultaneously, and then efficient techniques are required to solve the bottleneck problem of the VOD system. Patching is one of the most efficient techniques to overcome the bottleneck of the VOD system through the use of multicast scheme. In this paper, we propose a new patching scheme, called P2P proxy patching, for improving the typical patching technique by jointly using the prefix caching and P2P proxy. In our proposed scheme, each client plays a role in a proxy to multicast a regular stream to other clients that request the same video stream. Due to the use of the P2P proxy and the prefix caching, the client requests that ive out of the patching window range can receive the regular stream from other clients in the previous patching group without allocating the new regular channels from the VOD server to the clients. In the performance study, we show that our patching scheme can reduce the server bandwidth requirement about $33\%$ less than that of the existing patching technique with respect to prefix size and request interval.

A Multicast Middleware for the Remote Educational Systems (원격 교육 시스템을 위한 멀티캐스트 미들웨어)

  • Byun, Sang-Seon;Jin, Hyun-Wook;Yoo, Hyuck
    • Journal of KIISE:Computing Practices and Letters
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    • v.9 no.1
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    • pp.100-108
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    • 2003
  • By choosing Multicast for transmission of educational contents in the Remote Educational System, we can reduce the server load and increase network bandwidth utilization. We design and implement Multicast Middleware for the Remote Educational System in this paper. There are three characteristics in this Multicast Middleware: 1) Through Centralized Multicast Group Management for passive members, it allows a host to make multicast group, which is composed of receivers, called Group Member and who are chosen by the host, called group Maker. Because, all groups are created by the Group Maker in Centralized Group Management, Group Member's join action will be passive 2) Maintenance and recovery of multicast group information in order to restore from exception and crash; the maintenance and recovery mechanism of Group Maker is distinct from that of Group Member. 3) The mechanism which enables to transmit large size multimedia data through multicasting and remove additional copy operation through shared buffer. Fragmentation/de-fragmentation for large data delivery results in additional copy operation in user level. But by using user level shared buffer, it can be done without user Bevel copy operation. By applying to Remote Educational environment which consists of 30 PCs and Fast Ethernet, we can examine the efficiency of this middleware, which can transmit 18frames/sec movie which resolution 320 $\times$ 120 pixels, 128Kbps encoded sound data and some text data.

Video Retrieval System supporting Adaptive Streaming Service (적응형 스트리밍 서비스를 지원하는 비디오 검색 시스템)

  • 이윤채;전형수;장옥배
    • Journal of KIISE:Computing Practices and Letters
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    • v.9 no.1
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    • pp.1-12
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    • 2003
  • Recently, many researches into distributed processing on Internet, and multimedia data processing have been performed. Rapid and convenient multimedia services supplied with high quality and high speed are to be needed. In this paper, we design and implement clip-based video retrieval system on the Web enviroment in real-time. Our system consists of the content-based indexing system supporting convenient services for video content providers, and the Web-based retrieval system in order to make it easy and various information retrieval for users in the Web. Three important methods are used in the content-based indexing system, key frame extracting method by dividing video data, clip file creation method by clustering related information, and video database construction method by using clip unit. In Web-based retrieval system, retrieval method ny using a key word, two dimension browsing method of key frame, and real-time display method of the clip are used. In this paper, we design and implement the system that supports real-time display method of the clip are used. In this paper, we design and implement the system that supports real-time retrieval for video clips on Web environment and provides the multimedia service in stability. The proposed methods show a usefulness of video content providing, and provide an easy method for serching intented video content.