주문형 비디오 분배를 위한 웹-캐슁 멀티캐스트 전송 기법

김백현,황태준,김익수,Kim, Back-Hyun,Hwang, Tae-June,Kim, Ik-Soo 한국정보처리학회 2005 정보처리학회논문지B Vol.12 No.7

본 논문은 동일 비디오를 저장하고 있는 n개의 단말노드에서 생성되는 전송채널들을 병합하여 네트워크 대역폭을 n배 줄일 수 있는 멀티캐스트 전송 기법을 제안한다 클라이언트는 패칭 기법을 사용하여 전송중인 멀티캐스트 전송 트리에 가입함으로서 지연 없는 서비스를 제공받을 수 있으며 패칭과 멀티캐스트 채널을 통하여 전송되는 데이터들을 동시에 수신하여 재생한다. 비디오에 대한 요청빈도수가 증가할수록 요청된 비디오가 단말노드 사이에 저장될 확률은 증가하기 때문에 이를 이용하여 서비스를 제공함으로서 서버의 필요 전송채널수를 감소시킬 수 있다. 서버는 비디오 재생이 HEN 사이에 저장된 데이터의 양을 초과하여 지속되는 경우에만 새로운 멀티캐스트를 생성하여 전송한다. 제안된 기술은 비디오의 인기도에 따라 멀티캐스트 그룹 간격이 동적으로 변화되기 때문에 서버의 부하 및 네트워크 대역폭을 크게 감소시킬 수 있다 시뮬레이션 결과로부터 제안된 멀티캐스트 전송 기법은 서버의 부하 및 필요 전송 채널의 수를 감소시켜 시스템 성능을 향상시킬 수 있는 방법을 제시하고 있음을 확인하였다. In this paper, we propose multicast technique in order to reduce the required network bandwidth by n times, by merging the adjacent multicasts depending on the number of HENs (Head-End-Nodes) n that request the same video. Allowing new clients to immediately join an existing multicast through patching improves the efficiency of the multicast and offers services without any initial latency. A client might have to download data through two channels simultaneously, one for multicast and the other for patching. The more the frequency of requesting the video is, the higher the probability of caching it among HENs increases. Therefore, the requests for the cached video data can be served by HENs. Multicast from server is generated when the playback time exceeds the amount of cached video data. Since the interval of multicast can be dynamically expanded according to the popularity of videos, it can be reduced the server's workload and the network bandwidth. We perform simulations to compare its performance with that of conventional multicast. From simulation results, we confirm that the Proposed multicast technique offers substantially better performance.

Head-End-Network에서 대화형 서비스를 위한 멀티캐스트 VOD 시스템

김백현,황태준,김익수,Kim, Back-Hyun,Hwang, Tae-June,Kim, Ik-Soo 한국정보처리학회 2004 정보처리학회논문지B Vol.11 No.3

본 논문은 멀티캐스트 전송 네트워크 상에서 Head-End-Network(HNET) 및 BISM(Buffering algorithm for Interactive Services in Multicast)을 사용하여 VCR 서비스를 제공하는 대화형 VOD 시스템을 제안한다. HNET은 Switching Agent(SA)와 캐쉬를 적용한 Head-End-Nodes(HENs) 및 클라이언트로 구성되며, HENs는 SA의 제어하에 요청된 비디오 스트림을 분산저장하며, 클라이언트 버퍼는 다양한 VCR 재생률을 지원하기 위하여 BISM을 사용하여 동적으로 확장된다. 본 논문에서 대화형 VCR 서비스는 서버 또는 HENs에 의해 네트워크 상에 전송되는 비디오 스트림과 클라이언트 버퍼에 저장된 데이터만을 사용하여 제공된다. 그러므로 제안된 기술은 네트워크의 부하를 감소시킬 수 있으며, 서버로부터 불필요한 채널의 할당 및 중복된 비디오 컨텐츠의 전송을 제한하게 되어 시스템 성능을 향상시킬 수 있는 방법을 제시한다. This paper proposes an interactive VOD system to serve truly interactive VCR services using multicast delivery, client buffer and web-caching technique which implements the distributed proxy in Head-End- Network(HNET). This technique adopts some caches in the HNET that consists of a Switching Agent(SA), some Head-End-Nodes(HEN) and many clients. In this model, HENs distributively store the requested video under the control of SA. Also, client buffer dynamically expands to support various VCR playback rate. Thus, interactive services are offered with transmitting video streams from network, HENs and stored streams on buffer. Therefore this technique makes the load of network occur In the limited area, minimizes the additional channel allocation from server and restricts the transmission of duplicated video contents

이동 통신 시스템을 이용한 물류 관제 시스템

김백현(Back-hyun Kim),황태준(Tae-June Hwang),문승찬(Seung-Chan Moon),김익수(Ik-soo Kim) 한국정보기술학회 2009 한국정보기술학회논문지 Vol.7 No.1

In this paper, we propose logistics shipping system that can monitor the current location and status of being delivered products. The proposed system is consisted of two parts: mobile system and server system. Mobile system has GPS for calculating current location, RFID for monitoring product status and SMS for delivering information. Server system provides customers with information of the ordered products such as order status, product status and current location using visual map. To reduce the number of data delivered by SMS, it uses 4 kinds of delivery methods determined by the number of sensor information per SMS packet and the transition rate of sensor status. From simulation results, we confirm that the proposed logistics shipping system offers substantially better performance. With the development of logistics shipping system, we verify the availability of proposed system that can monitor the delivery, loading and unloading, the route for delivering and arrival of the ordered products.

Hop-based Aggressive Caching Scheme for Hybrid Mobile Ad-hoc Networks

Back-Hyun Kim(김백현),Kyeongmo Park(박경모) 한국디지털콘텐츠학회 2018 한국디지털콘텐츠학회논문지 Vol.19 No.12

Hybrid mobile ad hoc networks are networks that combine the Internet with mobile ad hoc networks. In the wireless transmission scheme, nodes located within the transmission range of each other can receive the transmitted content irrespective of destination. The caching technique stores such received content and uses it for future requests. This paper proposes an aggressive caching scheme based on the number of transport hops. In the proposed scheme, the service request and provision is made along the tree path with the AP as the root node. The node caches the received content based on its own hop count. When the routing process is completed, the node becomes a path node responsible for transmission or an adjacent node of the path node without any extra process. Simulation results show that the proposed caching scheme can achieve better performance compared to conventional aggressive caching scheme.

哲學 : 莊子與後現代主義

김백현 ( Back Hyun Kim ) 한국중국학회 2007 國際中國學硏究 Vol.10 No.-

다중 - 경로 다단계 상호연결 네트워크의 성능 개선

김백현(Kim Back Hyun),우요섭(Woo Yo Seop),김익수(Kim Ik Soo) 한국정보처리학회 1999 정보처리학회논문지 Vol.6 No.5

This paper proposes a new multipath multistage interconnection network(MIN) structure for improving performance which uses widely in the design of multiprocessing, ATM system and VOD server, For improving performance such as passthrough ratio and packet latency, it proposes new routing method which routes one of the collided packets into the i 1-th switching stage of the adding Banyan MIN network when it occured collision at the i-th switching stage of basic MIN, and the inserted collision packets into the adding MIN are routed into the i 2-th switching stage of the basic MIN again when they collide each other. The new improved performance MIN network has been compared with stage vs. passthrough ratio. It is shown to improve a performance and to be a simple structure which reducing the number of switching stage of adding MIN in comparison with other structured MIN including TBSF.

최근의 도시철도 신호시스템 기술에 관한 연구개발(1)

김종기(Kim Jong Ki),김용규(Kim Yong Kyu),이준호(Lee Jun Ho),김백현(Kim Back Hyun),신덕호(Shin Duck Ho),이기서(Lee Gey Seo) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-

The signalling systems, which are currently used in Urban Transit, are mostly using track_circuit based train control systems. However, as the development of radio communication technology, the radio communication technology based train control systems (of railway systems) are developed. In addition, the relevant studies are promoted in many countries. In this paper, "Track circuit Based Train Control" system and "Communication Based Train Control" system will be studied.

CBTC를 위한 상용 WCDMA망의 적용 가능성 연구

김용상(Kim Yong-Sang),고동환(Ko Dong-Hwan),은창수(Eun Chang-Soo),김백현(Kim back-hyun),윤용기(Yoon Yong-Ki) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

To study the feasibility of applying wireless communication technology to the control of train for the effective control of train and for the reduction of cost and time to construct the necessary infra structure, we investigate into the application of the existing commercial WCDMA network to CBTC (communication-based train control) to grasp the obstacles and propose the solutions to circumvent them. The obstacles can be categorized into the hand-off problem, the interference problem near the stations, and the problem of radio shadow areas. We propose, as solutions, the cell overlap method and multi-terminal approach for the hand-off problem, the cell sectoring method for the interference problem, and establishment of new base stations along the railroad both to provide the wireless train control and communication service to the customers on the train which was otherwise impossible because of the shadowing effect.

IMT-2000에서 기지국용 스마트 안테나를 적용한 MC/DS-CDMA 시스템의 성능분석

박인규(In-Kyu Park),김백현(Back Hyun Kim),신승훈(Seung Hum Shin),곽경섭(Kyung Sup Kwak) 한국통신학회 2001 한국통신학회 학술대회논문집 Vol.2001 No.7

모바일 애드-혹 무선 통신망의 스트리밍 서비스를 위한 부분적 캐싱

박경모(Kyeongmo Park),김백현(Back-Hyun Kim) 한국디지털콘텐츠학회 2022 한국디지털콘텐츠학회논문지 Vol.23 No.3

Mobile ad-hoc wireless networks are the networks comprised of freely moving nodes only. Due to the free movement of nodes in mobile ad-hoc networks, the network topology changes every moment. In this paper, the content being transmitted is cached at the nodes constituting the route and the requesting node. For the delayless streaming service, the requesting node requests and caches consecutive frames necessary for future playback from the current frame of the content to the neighboring node as much as the window size. The performance evaluation was compared and analyzed with the aggressive caching scheme that unconditionally stores received data in terms of cache hit ratio and transmission channel ratio. Simulation results show that our partial caching has a high cache hit ratio and a low number of transmission channels. Our proposed scheme may be an alternative technique to increase the available energy and transmission efficiency of nodes in mobile networks.