• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1142-1147
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• 2015

As a method to increase the scalability and efficiency of wireless sensor networks, a scheme to construct networks hierarchically has received considerable attention among researchers. Researches on the methods to construct wireless networks hierarchically have been conducted focusing on how to select nodes such that they constitute a backbone network of wireless network. Nodes comprising the backbone network should be connected themselves and can cover other remaining nodes. A problem to find the minimum number of nodes which satisfy these conditions is known as the minimum connected dominating set (MCDS) problem. The MCDS problem is NP-hard, therefore there is no efficient algorithm which guarantee the optimal solutions for this problem at present. In this paper, we propose a novel multi-start local search algorithm to solve the MCDS problem efficiently. For the performance evaluation of the proposed method, we conduct extensive experiments and report the results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.117-124
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• 2004

With MPEG-4 3D mesh coding(3DMC), the problem of the need of a wide bandwidth can be solved to store and transmit 3D information because of its high compression rate. And to realize the 3D information service with broadcasting or internet, one needs to transmit not only the 3D contents but also the 3D player. Therefore, in this paper we implement a 3D player based on MPEG-4 using a java language. A well-known java language employed in this paper provides the player with a wider range of applications, for example, when the O/S or the platform are different, due to its properties of scalability and universality. The implemented player which has functions (translation, rotation, etc) that can manipulate contents decodes the 3D contents and displays them. In addition, the player has a network function that receives a 3D content from the server. This paper explains the architecture and characteristics of the player and shows its simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1947-1954
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• 2009

Service discovery mechanism is a core technique for getting a desired service in MANET(Mobile Ad-Hoc NETwork) environment. However, As feature of MANET, existing mechanisms have some problem that service requester search for trustable service. also it can not support scalability. in this paper, how to reliably support applications such as service discovery on top of MANET. we are firstly finding a trustable service provider and configure DHT(Distributed Hash Table). P2P's DHT can be adopted to service discovery mechanism because P2P and MANET share certain similarities, primarily the fact that both are instances of self-organizing decentralized systems. Especially, Proposed DHT systems used for P2P overlay network can be effective in reducing the communication overhead in service discovery. So proposed mechanism can support for reliably searching required service and scalability. Simulation results show that our mechanism is scalable and outperforms existing service discovery mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1183-1190
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• 2017

With the development of network and IT technology, people are searching and purchasing items they want, not bounded by places. Therefore, there are various studies on how to solve the scalability problem due to the rapidly increasing data in the recommendation system. In this paper, we propose an item-based collaborative filtering method using Tag weight and a recommendation technique using MapReduce method, which is a distributed parallel processing method. In order to improve speed and efficiency, the proposed method classifies items into categories in the preprocessing and groups according to the number of nodes. In each distributed node, data is processed by going through Map-Reduce step 4 times. In order to recommend better items to users, item tag weight is used in the similarity calculation. The experiment result indicated that the proposed method has been more enhanced the appropriacy compared to item-based method, and run efficiently on the large amounts of data.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.11
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• pp.1305-1317
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• 1999

NUMA 구조는 원격 메모리에 대한 접근이 불가피한 구조적 특성 때문에 상호 연결망이 성능을 좌우하는 큰 변수가 된다. 기존에 대중적으로 사용되던 버스는 물리적 확장성 및 대역폭에서 대규모 시스템을 구성하는 데 한계를 보인다. 이를 대체하는 고속의 지점간 링크를 사용한 링 구조는 버스가 가지는 확장성 및 대역폭의 한계라는 단점을 개선하였으나, 많은 클러스터가 연결되는 경우에는 전송 지연시간이 증가하는 문제점을 가지고 있다. 본 논문에서는 스누핑 프로토콜이 적용된 링 구조에서 클러스터 개수 증가에 따른 지연시간 증가의 문제점을 보완하기 위해 계층적 링 구조로의 확장을 제안하고, 이 구조에 효과적인 캐쉬 일관성 프로토콜을 설계하였다. 전역 링과 지역 링을 연결하는 브리지는 캐쉬 프로토콜을 관리하며 이 프로토콜에 의해 지역 링의 부하를 줄일 수 있도록 트랜잭션을 필터링하는 역할도 담당함으로써 시스템의 성능을 향상시킨다. probability-driven 시뮬레이터를 통해 계층적 링 구조가 시스템의 성능 및 링 이용률에 미치는 영향을 알아본다. Abstract Since NUMA architecture has to access remote memory, interconnection network performance determines performance of NUMA architecture. Bus, which has been used as popular interconnection network of NUMA, has a limit to build a large-scale system because of limited physical scalability and bandwidth. Ring interconnection network, composed of high-speed point-to-point link, made up for bus's defects of scalability and bandwidth. But, it also has problem of increasing delay as the number of clusters is increased. In this paper, we propose a hierarchical expansion of snoop-based ring architecture in order to overcome ring's defects of increasing delay. And we also design an efficient cache coherence protocol adopted to this architecture. Bridge, which connects local ring and global ring, maintains cache coherence protocol and does snoop-filtering which reduces local ring and cluster bus utilization. Therefore bridge can improve performance of this system. We analyze effects of hierarchical architecture on the performance of system and utilization of point-to-point links using probability-driven simulator.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.1
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• pp.19-24
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• 2007

Abstract. In the ubiquitous environment of the next generation, RFID is predicted to occupy an important technical location and also expected to apply to various fields. However, the properties of tags in itself which is the core of RFID have a dysfunction like an invasion of privacy for user. An existing cryptanalytic protection scheme of the information leakage have a difficult problem to apply to RFID tags for privacy protection. We applied Ohkubo et al.'s scheme to the protection of the tag's information efficiently in the RFID system environment using low-cost tags. But, this method has all informations of tagsto identify tag's ID and then performs the process of identification in sequence in the Back-end server. These processes have lots of computations so that it have problems about a scalability. In this paper, we are based on Ohkubo et al.'s scheme to solve problems, and then analyze the parallelism with the Hellman's tradeoff method, divide it into nodesin parallel. In this paper, we are based on Okubo et al.'s scheme to solve problems, and then analyze the parallelism with Hellman's tradeoff method, divide it into the ${\omega}$ node in parallel. as a result, we can reduce the computing complexity of key search to $O(\frac{m^{2/3}n^{2/3}}{\omega})$ seconds from O(mm) seconds. finally we show the results to be enhanced the scalability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1428-1434
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• 2006

In this paper, we propose the scheme solving privacy infringement in RFID systems with improving the scalability of back-end server. With RFID/USN becoming important subject, many approaches have been proposed and applied. However, limits of RFID, low computation power and storage, make the protection of privacy difficult. The Hash Chain scheme has been known as one guaranteeing forward security, confidentiality and indistinguishability. In spite of that, it is a problem that requires much of computation to identify tags in Back-End server. In this paper, we introduce an efficient key search method, the Hellman Method, to reduce computing complexity in Back-End server. Hellman Method algorism progresses pre-computation and (re)search. In this paper, after applying Hellman Method to Hash chain theory, We compared Preservation and key reference to analyze and apply to parallel With guaranteeing requistes of security for existing privacy protecting Comparing key reference reduced computation time of server to reduce computation complex from O(m) to $O(\frac{m{^2/3}}{w})$ than the existing form.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.16-18
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• 2004

Single system image(SSI) have been the mainstay high-performance computing for many years. SSI requires the integration and aggregation of all types of resources in a cluster to present a single interface to users. In this paper, we describe a cluster computing architecture with the concept of single process space(SPS) where all processes share a uniform process identification scheme. With SPS, a process on any node can create child process on the same or different node or communicate with any other process on a remote node, as if they are on a single node. For this purpose, SPS is built with the support of unique cluster-wide pid, signal forwarding, and remote fork. We propose a novel design of SPS cluster which addresses the scalability and flexibility problem of traditional clusterwidely unique pid implementation by using blocked pid assignment. We have implemented this new design of SPS cluster, and we demonstrate its performance by comparing it to Beowulf distributed process space. Benchmark performance results show that our design of SPS cluster realized both scalability and flexibility that are essential to building SPS cluster.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.709-722
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• 2020

Point Cloud which is a cluster of numerous points can express 3D object beyond the 2D plane. Each point contains 3D coordinate and color data basically, reflectance or etc. additionally. Point Cloud demand research and development much higher effective compression technology. Video-based Point Cloud Compression (V-PCC) technology in development and standardization based on the established video codec. Despite its high effective compression technology, point cloud service will be limited by terminal spec and network conditions. 2D video had the same problems. To remedy this kind of problem, 2D video is using Scalable High efficiency Video Coding (SHVC), Dynamic Adaptive Streaming over HTTP (DASH) or diverse technology. This paper proposed a density scalability method using SHVC codec in V-PCC.