• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.232-239
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• 2009

Emerging social networking services provide a new paradigm for human-to-human communication. However, these services are centralized and managed by single service provider. In this paper, we propose MicroPost, a decentralized event notification service architecture for social applications based on publish/subscribe model. In our design space, event brokers are structured as an overlay network which provides the substrate of distributed peer-to-peer lookup service for storing and retrieving subscriptions with hashed keys. Event clients interact with event brokers to publish or subscribe social messages over the wide-area network. Using XML standards, we present an efficient algorithm to forward events for rendezvous-based matching in this paper. In our design space, the cost of routing is O(${\omega}log_kN$), where N is the number of event brokers, ${\omega}$ is the number of meta-data obtained from event messages, and k is a constant, which is selected by our design, to divide the identifier space and to conquer the lookup of given key. Consequently, what we achieved is an asynchronous social messaging service architecture which is decentralized, efficient, scalable, and flexible.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2267-2285
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• 2016

Information Centric Networking that uses content name instead of IP address as routing identifier can handle challenges such as traffic explosion and user mobility, but it also suffers from scalability and incompatibility problems. In this paper by combining the concept of software defined networking and Internet end to end arguments, we propose a wide area deployable software defined information centric networking service model named SD-ICN. SD-ICN employs a dual space structure that separates edge service network and core transmission network. The enhanced SDN techniques are used in edge service network in order to implement intelligent data routing and caching, while traditional IP technique is reserved in core transmission network so as to provide wide area high speed data transmission. Besides, a distributed name resolution system based on the cooperation of different controllers is also presented. The prototype experiments in our campus network show that SD-ICN can be deployed in a scalable and incremental way with no modification of the core network, and can support typical communication modes such as multicast, mobility, multihoming, load balancing, and multipath data transmission effectively.

• Journal of Communications and Networks
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• v.12 no.2
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• pp.181-190
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• 2010

A multitude of overlay network designs for resilient routing, multicasting, quality of service, content distribution, storage, and object location have been proposed. Overlay networks offer several attractive features, including ease of deployment, flexibility, adaptivity, and an infrastructure for collaboration among hosts. In this paper, we explore cooperation among co-existing, possibly heterogeneous, overlay networks. We discuss a spectrum of cooperative forwarding and information sharing services, and investigate the associated scalability, heterogeneity, and security problems. Motivated by these services, we design Synergy, a utility-based overlay internetworking architecture that fosters overlay cooperation. Our architecture promotes fair peering relationships to achieve synergism. Results from Internet experiments with cooperative forwarding overlays indicate that our Synergy prototype improves delay, throughput, and loss performance, while maintaining the autonomy and heterogeneity of individual overlay networks.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.4
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• pp.93-102
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• 1995

This paper introduces a general purpose Associative Processor(AP) which is very efficient for search-oriented applications. The proposed architecture consists of three main functional blocks: Content-Addressable Memory(CAM) arry, row logic, and control section. The proposed AP is a Single-Instruction, Multiple-Data(SIMD) device based on a CAM core and an array of high speed processors. As an application for the proposed hardware, we present a parallel algorithm to solve a global routing problem in the layout process utilizing the processing capabilities of a rudimentary logic and the selective matching and writing capability of CAMs, along with basic algorithms such a minimum(maximum) search, less(greater) than search and parallel arithmetic. We have focused on the simultaneous minimization of the desity of the channels and the wire length by sedking a less crowded channel with shorter wire distance. We present an efficient mapping technique of the problem into the CAM structure. Experimental results on difficult examples, on randomly generated data, and on benchmark problems from MCNC are included.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2398-2415
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• 2017

Content-Centric Networking (CCN) is a new Internet architecture with routing and caching centered on contents. Through its receiver-driven and connectionless communication model, CCN natively supports the seamless mobility of nodes and scalable content acquisition. In-network caching is one of the core technologies in CCN, and the research of efficient caching scheme becomes increasingly attractive. To address the problem of unbalanced cache load distribution in some existing caching strategies, this paper presents a neighbor cooperation based in-network caching scheme. In this scheme, the node with the highest betweenness centrality in the content delivery path is selected as the central caching node and the area of its ego network is selected as the caching area. When the caching node has no sufficient resource, part of its cached contents will be picked out and transferred to the appropriate neighbor by comprehensively considering the factors, such as available node cache, cache replacement rate and link stability between nodes. Simulation results show that our scheme can effectively enhance the utilization of cache resources and improve cache hit rate and average access cost.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.421-429
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• 2006

Recently, DHT-based Structured P2P System have a attention to scalability and providing efficient lookup by routing. Retrieving content of DHT-based P2P require knowledge of the exact identifier of sharing file. But user may wish to search for sharing file using descriptive keyword or content. To resolve the problem, this paper propose Extended-CAN mechanism to support keyword search. We defined content-based keyword and identifier of sharing file, and PLS extended to KID and CKD for keyword, common keyword processing. As a result, Extended-CAN mechanism provide efficient keyword search for DHT-based Structured P2P System.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.583-585
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• 2004

컨텐츠 기반의 네트워크 상에서 효율적인 이벤트 전달 방법은 계속적으로 연구가 진행 중인 분야이다. 기존에는 컨텐츠 기반의 라우팅을 위한 방안으로 크게 필터 기반의 라우팅 방식과 멀티캐스트 기반의 라우팅 방식으로 나누어 접근해 왔다. 그러나 이 두 가지 방식은 라우팅 정보의 저장 및 관리 비용과 정확한 이벤트의 전달 간에 트레이드 오프가 발생한다. 본 논문에서는 해시 그룹 기반의 라우팅 기법을 제안하며, 이 방식을 통해 모든 노드에게 원하는 정보의 정확한 전달이 가능할 뿐 아니라, n개의 서로 다른 컨텐츠에 대해 각 노드에서 유지해야 하는 라우팅 엔트리의 수가 O(√n)이 됨을 보였다.

• Journal of Information Processing Systems
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• v.12 no.4
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• pp.577-590
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• 2016

We studied the current state-of-the-art of Smart TV, the challenges and the drawbacks. Mainly we discussed the lack of end-to-end solution. We then illustrated the differences between Smart TV and IPTV from network service provider point of view. Unlike IPTV, viewer of Smart TV's over-the-top (OTT) services could be global, such as foreign nationals in a country or viewers having special viewing preferences. Those viewers are sparsely distributed. The existing TV service deployment models over Internet are not suitable for such viewers as they are based on content popularity, hence we propose a community based service deployment methodology with proactive content caching on rendezvous points (RPs). In our proposal, RPs are intermediate nodes responsible for caching routing and decision making. The viewer's community formation is based on geographical locations and similarity of their interests. The idea of using context information to do proactive caching is itself not new, but we combined this with "in network caching" mechanism of content centric network (CCN) architecture. We gauge the performance improvement achieved by a community model. The result shows that when the total numbers of requests are same; our model can have significantly better performance, especially for sparsely distributed communities.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.24-34
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• 2001

IP address lookup is a major bottleneck of IP packet processing in high speed router. Existing IP lookup methods are focused only on lookup throughput without considering lookup table update. So their slow update can lead to lookup blocking or wrong routing decision based on obsolete routes. Especially existing IP lookup methods based on CAM(content addressable memory) have slow update of O(n) cycles in spite of their high throughput and low area complexity In this paper we proposes a new IP address lookup method based on pipelined CAM architecture(PICAM) with fast update of O(1) cycle of lookup table and high throughput and low area complexity.

• Journal of Information Processing Systems
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• v.6 no.3
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• pp.269-294
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• 2010

The interconnection of mobile devices in urban environments can open up a lot of vistas for collaboration and content-based services. This will require setting up of a network in an urban environment which not only provides the necessary services to the user but also ensures that the network is secure and energy efficient. In this paper, we propose a secure, energy efficient dynamic routing protocol for heterogeneous wireless sensor networks in urban environments. A decision is made by every node based on various parameters like longevity, distance, battery power which measure the node and link quality to decide the next hop in the route. This ensures that the total load is distributed evenly while conserving the energy of battery-constrained nodes. The protocol also maintains a trusted population for each node through Dynamic Trust Factor (DTF) which ensures secure communication in the environment by gradually isolating the malicious nodes. The results obtained show that the proposed protocol when compared with another energy efficient protocol (MMBCR) and a widely accepted protocol (DSR) gives far better results in terms of energy efficiency. Similarly, it also outdoes a secure protocol (QDV) when it comes to detecting malicious nodes in the network.