• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.775-782
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• 2005

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.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.615-622
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• 2006

Caching in a Wireless Internet Proxy Server Cluster Environment has an effect that minimizes the time on the request and response of Internet traffic and Web user As a way to increase the hit ratio of cache, we can use a hash function to make the same request URLs to be assigned to the same cache server. The disadvantage of the hashing scheme is that client requests cannot be well-distributed to all cache servers so that the performance of the whole system can depend on only a few busy servers. In this paper, we propose an improved load balancing scheme using hashing and Round Robin scheme that distributes client requests evenly to cache servers. In the existing hashing scheme, if a hashing value for a request URL is calculated, the server number is statically fixed at compile time while in the proposed scheme it is dynamically fixed at run time using round robin method. We implemented the proposed scheme in a Wireless Internet Proxy Server Cluster Environment and performed experiments using 16 PCs. Experimental results show the even distribution of client requests and the 52% to 112% performance improvement compared to the existing hashing method.

• Journal of the Korea Computer Industry Society
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• v.2 no.11
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• pp.1453-1464
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• 2001

Explosive growth of Internet populations results performance degradations of web service. Popular web sites cannot provide proper level of services to many requests, and such poor services cannot give user a satisfaction. Web caching, the remedy of this problem, reduces the amount of network traffic and gives fast response to user. In this paper, we analyze the characteristics of web cache traffics using traces of NLANR(National Laboratory for Applied Network Research) root caches and Education network cache in Seoul National University. Based on this analysis, we suggest a method of prefetching and we discuss the gains of our prefetching. As a result, we find proposed prefetching enhances hit rate up to 3%, response time up to 5%.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.631-636
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• 2006

최근 많은 사용자들이 인터넷 상에서 비디오나 오디오 같은 규모가 큰 미디어 콘텐츠(Media contents)의 정보 전달을 효율적으로 제공 받기를 원하고 있다. 미디어 콘텐츠를 스트리밍 하는 것은 인터넷 트래픽의 아주 큰 부분을 차지하기 때문에, 우리는 클러스터형 협업 프록시를 기반으로 한 다중 디스크립션 비디오 스트리밍 구조를 제안하여 네트워크와 서버의 부하를 클러스터된 일반 프록시들에게 균등하게 분산 시킨다. MDC(Multiple Description Coding)[1]를 적용하여 캐싱 공간(Caching space)을 효율적으로 사용하며 다중 세션을 통해 디스크립션을 서비스함으로써 스트리밍 서비스 중인 프록시 또는 전체 데이터를 저장하고 하는 서버에 문제가 생기더라도 끊어지지 않는 계속적인 서비스가 가능하다. 또한 일반 프록시들의 정보를 관리하는 디스패처가 사용자의 환경에 따라 적응적인 서비스를 가능하게 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.313-315
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• 2005

사회적으로 큰 관심의 대상이 되고 있는 무선 인터넷은 유선 인터넷과 달리 기술 환경과 그 특성상 여러 가지 제약점들을 가지고 있다. 대역폭이 낮고, 접속이 빈번하게 끊기며, 단말기내의 컴퓨팅 파워가 낮고 화면이 작다. 또한 사용자의 이동성 문제와 네트워크 프로토콜, 보안 등에서 아직 기술적으로 부족한 부분을 보이고 있다. 그리고 급속도로 증가하는 수요에 따라 무선 인터넷 서버는 대용량 트래픽을 처리할 수 있는 확장성이 요구되어지고 있다. 이에 본 논문에서는 무선 인터넷 프록시 서버 클러스터를 사용하여 앞에서 언급된 무선 인터넷의 문제와 요구들을 캐싱(Caching), 압축(Distillation) 및 플러스터(Clustering)를 통하여 해결하려고 한다. TranSend는 클러스터링 기반의 무선 인터넷 프록시 서버로 제안된 것이나 시스템적인(Systematic) 방법으로 확장성을 보장하지 못하고 불필요한 모듈간의 통신구조로 인해 복잡하다는 단점을 가진다. 기존 연구에서 시스템적인 방법으로 확장성을 보장하는 CD-A라는 구조를 제안하였으나 이 역시 모듈간의 불필요한 통신 구조를 가진다는 단점을 있다. 이에 본 논문에서는 시스템적인 확장성과 단순한 구조를 가지는 새로운 클러스터링 기반의 무선 인터넷 프록시 서버를 제안한다. 16대의 컴퓨터를 사용하여 실험을 수행하였고 실험 결과 TranSend 시스템과 CD-A 시스템에 비해 각각 $216\%,\;40\%$의 성능 향상을 보였다.

• The KIPS Transactions:PartB
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• v.11B no.3
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• pp.361-368
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• 2004

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

• Journal of Digital Convergence
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• v.14 no.6
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• pp.405-413
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• 2016

To solve various problems of the Internet as well as to enhance network performance, various future Internet architectures utilize cached data in network nodes or in proxy servers. Named-data networking (NDN), one of future Internet architectures, implements in-network data caching functionality, and then responds itself to request messages. However, it can cause users' privacy invasion that the publisher of data can not engage in the sharing/using process of the data anymore after the data was cached in-network. So NDN implements both encryption-based access control and group access control. But, since such access control schemes need to exchange additional messages in order to search for a proper access control list and keys, it causes inefficiency. This paper surveys the access control schemes of NDN, and then proposes an improved scheme.