• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.5
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• pp.444-460
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• 2009

In this paper, we propose an expanded patching technique in order to reduce the server network bandwidth requirements to support true VoD services in VoD Systems. Double Patching, which is a typical multicast technique, ensures that a long patching stream delivers not only essential video data for the current client but also extra video data for future clients. Since the extra data may include useless data, it results in server network bandwidth wastage. In order to prevent a server from transmitting useless data, the proposed patching technique uses a new kind of stream called a linking stream. A linking stream is transmitted to clients that have received short patching streams, and it plays a linking role between a patching stream and a regular stream. The linking stream enables a server to avoid transmitting unnecessary data delivered by a long patching stream in Double Patching, so the server never wastes its network bandwidth. Mathematical analysis shows that the proposed technique requires less server network bandwidth to support true VoD services than Double Patching. Moreover, simulation results show that it has better average service latency and client defection rate compared with Double Patching.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.10-18
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• 2013

With advancing of mobile communication services and commercializing of VoLTE (Voice of LTE), it is getting to pay attention on QoS of VoLTE. This paper proposes an integrated E-model in which some factors influenced to service quality of VoIP and VoLTE based voice communication system are considered in calculating the voice quality of Wideband Codec. The model aims to calculate R value which reflects the situations of access network, network characteristics, terminals' usage and mobility. We mainly deal with the integrated E-model's structure, related algorithms and optimal parameters for VoLTE. Some experiments show that the voice quality difference between VoIP and VoiceChecker, and VoLTE and POLQA, is below 10%. With the proposed model, we can calculate the voice quality by making use of the factors directly affected to service quality and the environment of VoLTE terminal and network. As a result, we can estimate the service quality in advance, without measuring it in real wireless environment.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.577-593
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• 2000

A distributed video-on-demand (VoD) system is one where collection of video data is located at dispersed sites across a computer network. In a single site environment, a local video server retrieves video data from its local storage device. However, in the setting of a distributed VoD system, when a customer requests a movie from the local server, the server may need to interact with other servers located across the network. In this paper, we present three types of presentation plans that a local server must construct in order to satisfy the customer request. Informally speaking, a presentation plan is a temporally synchronized detailed sequence of steps that the local server must perform for presenting the requested movie to the customer. This involves obtaining commitments from other video servers, obtaining commitments from the network service provider, as well as making commitments of local resources, within the limitations of available bandwidth, available buffer, and customer data consumption rates. Furthermore, for evaluating the goodness of a presentation plan, we introduce two measures of optimality for presentation plans: minimizing wait time for a customer, and minimizing access bandwidth is used. We develop algorithms to compute optimal presentation plans for all three types, and carry out extensive experiments to compare their performance. We have also mathematically proved certain results for the presentation plans that had previously been verified experimentally in the literature.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.65-65
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• 2000

For Video on Demand(VoD) servers, a design of an efficient scheduler is important to the support a large number of clients having various playback speeds and receiving rates. In this paper, we propose the scheduling algorithm to handle establishing deadlines and selection using the earliest deadline first. To establish deadlines and selections, the period of the receiving rates for each client is located between the over-max receiving rate and the over-playback rate. To avoid video starvation and the buffer overflow of each client, the proposed algorithm guarantees providing the admission control. Because of establishing deadlines and selection, period of each client receiving is between one over max receiving rate and one over play back rate. Using Virtual Buffer in server, scheduling load is reduced. The efficiency of the proposed algorithm is verified using a Petri Net_Based simulation tool, Exspect.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.207-212
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• 2004

This paper provides the higher user QoS(Quality of Service) by analyzing media service model between server and client in single VoD(Video on Demand) environment and applying it to parallel VoD environment. Media service model is divided into the Client Pull, Server Push, and IPP(Interleaving Pull & Push) model. A server sends data based on client's request in the Client Pull Model. A server one-sidedly sends data without client's request in the Server Pull model. And the WP model unites above two models. For a parallel VoD environment, We built the PMSS system which provides the parallel media streaming services that one client is simultaneously served by several servers. In the single and parallel VoD environment, We compare and analyze the performance of service models with respect to network delay and data size in buffer. In this experiment, we found that IPP service model keeps the least network delay and stable client buffer in the parallel VoD environment. This result shows that PMSS can provide the more quality of service.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.602-607
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• 2007

최근 4G 이동통신 시스템의 진화를 위한 단계로 기존의 이동통신 시스템을 유지하면서 효율 극대화를 통한 비용 절약 측면과 고 주파수 대역을 이용한 셀 간격의 협소화로 인해 나타나는 문제점에 대한 대안으로 커버리지 확대와 데이터 처리율 향상을 위한 IEEE 802.16j 표준화 작업이 진행 중에 있다. 향후 VoIP 서비스를 위한 업링크 스케줄링 기법으로 몇 가지가 IEEE 802.16j에 제시되어 있으나, 본 논문에서는 보이스 트래픽 특성 및 수학적 모델링을 통하여 기존 방법들보다 더 효율적인 대역 이용을 통해 같은 대역폭 대비 성능과 용량 면에서 개선된 스케줄링 기법인 eertPS를 제시하여 IEEE 802.16j Multi-Hop 환경하에서도 대역 효율적인 VoIP 서비스를 이용할 수 있도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.765-768
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• 2007

P2P Video-on-Demand (VoD) is becoming a popular service in the Internet. The first deployments are already in place, and millions of customers worldwide are already using this new medium. But its success is still quite limited and technically, these researches have been deployed in a rush, mostly based on practicality and instability. This paper studies the advantages and potential problems of VoD in peer-to-peer (P2P) network, we propose a system which uses a distributed VoD streaming scheme over P2P network to support media streaming.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.4
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• pp.135-142
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• 2011

Convergence between telecom and broadcasting is today a worldwide phenomenon. Diverse services like VoD, mobile broadcasting, IPTV and interactive services have already made their market debut or are currently being commercialized. Regulatory systems are also being revised to appropriately regulate this new breed of services. We propose the new model of educational broadcasting system using the internet network, it is not different conventional coaxial cable methods. Especially, we design the multicast method of the network using the limited channel and resource, propose the method of intercommunication in the school between the broadcasting system and database system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7B
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• pp.668-678
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• 2006

In designing a video-on-demand (VoD) system, one of the major challenges is how to reduce the viewer's waiting time maintaining a given bandwidth allocation and how to reduce the client's buffer requirements. To solve these problems, many VoD schemes were proposed. However, most VoD schemes require managing many segments of a video, frequency channel hopping, and using many channels at the same time. Therefore, to the complexity is a barrier to implementation. In this paper, we propose a fast staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The numerical results demonstrate that the viewer's waiting time of the fast staggered broadcasting scheme is close to the fast broadcasting scheme and the buffer requirements of this can be adapt for demanding rate by adjusting the short front part of a video sizes.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.352-359
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• 2006

VoD 전송 방식을 설계할 때 가장 중요한 요소들에는 정해진 대역폭에서 사용자 대기시간 (Viewer's Waiting Time)과 클라이언트에서 요구하는 최대 버퍼 요구량(Max Client Buffer Requirement)을 줄이는 문제를 꼽을 수 있다. 점점 더 복잡해지는 VoD 전송 기술의 개발로 인해 사용자 대기시간과 최대 버퍼 요구량의 관점에서 성능 향상과 반비례하는 시스템 복잡도를 줄이는 문제 또한 VoD 전송 방식을 설계 시 고려 해야 할 중요 사항 중의 하나이다. 이 논문에서는 시스템 복잡도를 낮추면서 사용자 대기시간과 최대 버퍼 요구량의 성능을 동시에 향상시키기 위한 방법으로 기존의 VoD 전송 방식들 가운데 가장 간단한 모델과 최대 버퍼 요구량의 성능을 가장 향상시킨 모델의 결합으로 구현 가능한 Hybrid 방식을 제안하고 있다. 이 논문은 결과적으로 사용자 대기시간은 기존 Staircase Broadcasting방식과 Fast Broadcasting 방식과 비교했을 때 동일한 성능을 나타내고 있고 최대 버퍼 요구량은 유사성능을 나타냄을 알 수 있다. 이 논문에서 제안한 방식은 사용자 대기시간이 짧아야 하고 저장공간이 많이 요구되지 않으며 사용자의 요청이 갑자기 증가될 수 있는 hot 비디오에 적용이 가능하다. 또한 다양한 환경에 따라 Staggered Broadcasting 방식과 Staircase Broadcasting 방식의 채널 수를 적절히 조정함으로써 데이터 송수신 효율을 극대화 시킬 수 있다. 이 논문의 구성은 제시한 방법에 적용된 방식들과 비교대상이 되는 방식들에 대해 살펴보고 제시한 방식의 성능 모델을 이용한 실험을 통해 각종 VoD 전송 방식들과 비교 분석하는 과정으로 기술하였다.