• The Journal of Information Systems
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• v.17 no.3
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• pp.135-152
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• 2008

Basically within a special regional area, a regional cluster seems to be based on core competencies of individual intra-cluster companies and collaboration among them. Information infrastructure has been emphasized as on one of competitive factors of a regional cluster, and it can be organized using collaboration system architecture integrated with each company's internal systems for efficient supply chain operation. As one of technical methods to prepare the system infrastructure supporting the collaboration of companies in a regional cluster, the Web Services can be effectively used. In this paper, a collaborative information system infrastructure for a regional cluster is suggested within the scope of supply chain management. And the efficiency of the proposed alternative is appraised with the features of a regional cluster.

• Journal of the Korea Computer Industry Society
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• v.3 no.2
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• pp.227-234
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• 2002

An cluster web server system, one has the problem that does the low availability occured by the high chance of the server failures and it is not easy to provide high performance and availability occuring software aging. In this paper, running cluster web sewers consists of n primary servers and k backup servers, propose software rejuvenation model on performance and switchover time. Based on the various system operational parameters, we calculate to evaluate the rejuvenation policy such steady-state probabilities, availability, and downtime cost. And we validate the solutions of mathematical model by experiments based on various operation parameters and fud that the software rejuvenation method can be adopted as prventive fault tolerant technique for stability of system.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1097-1106
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• 2004

The typical web cluster architecture consists of replicated real servers and a virtual server that routes client requests among the real servers. In this paper, we proposed an efficient dynamic load distribution method with load prediction for the web cluster systems. The virtual server transmit status request message to real servers in other to get load states. However the load states dose not accurate during load distribution, thus the virtual server predict the load status of real servers and assign a request of the client to the minimum loaded real server. The proposed distribution methods works not related to partial breakdown of real servers, thus the system works with high availability. We also show that the proposed distribution method preserve scalable property and improve the throughput through a set of simulations.

• Journal of Internet Computing and Services
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• v.6 no.2
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• pp.69-84
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• 2005

As the Internet users are increasing rapidly, a cluster web server system is attracted by many researchers and Internet service providers. The cluster web server has been developed to efficiently support a larger number of users as well as to provide high scalable and available system. In order to provide the high performance in the cluster web server, efficient load distribution is important, and recently many content-aware request distribution techniques have been proposed. In this paper, we propose a new content-aware load balancing technique that can evenly distribute the workload to each node in the cluster web server. The proposed technique is based on the hash histogram transformation, in which each URL entry of the web log file is hashed, and the access frequency and file size are accumulated as a histogram. Each user request is assigned into a node by mapping of (hashed value-server node) in the histogram transformation. In the proposed technique, the histogram is updated periodically and then the even distribution of user requests can be maintained continuously. In addition to the load balancing, our technique can exploit the cache effect to improve the performance. The simulation results show that the performance of our technique is quite better than that of the traditional round-robin method and we can improve the performance more than $10\%$ compared with the existing workload-aware load balancing(WARD) method.

• Journal of Korea Multimedia Society
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• v.4 no.6
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• pp.534-542
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• 2001

Recent content-based image retrieval systems make use of a local single server contained a limited number of images. So these systems are not satisfactory for the Web user's needs that make request for various images on the Web. A content-based image retrieval system that has regard for a great number of Web images has to stand on the basis of real-time first of all. Therefore, to implement the above system we have to resolve a problem of large waste time to take for an image collection and feature extractions. In recent, PC clusters with a load distribution are implemented for the purpose of high-performance data processing. In this paper, we decreased the whole retrieval time by distributing the tasks of image collection and feature extraction to take much time among the slave computers of the PC cluster, and so we found the possibility of the real-time processing in the retrieval of Web images.

• Journal of information and communication convergence engineering
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• v.3 no.2
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• pp.93-95
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• 2005

In order to create security session, security keys are preconfigured between communication objects. For this purpose, Handshake Protocol exists. The pre-master secret key that is used in this process needs to interpreted by a server to create master secret key, whose process requires a big calculation, resulting in deteriorating system's transmission performance. Therefore, it is helpful in increasing transmission speed to reuse secret keys rather than to create them at every connection.

• Korean Journal of Remote Sensing
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• v.17 no.4
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• pp.359-368
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• 2001

The prototype of forest fire management system on Web was studied. In the architecture of this system, one of the most important concerns is to handle load upcoming to Web Server so that it provides Web service without any delay or failure. In order to solve this problem, the agent is designed on dispatcher in a Web server cluster and implemented to distribute load dynamically by considering the information related to load coming to the Web Server such as the number of connection to the Map Server. The proposed forest fire management system has user-friendly interface with the GIS mapping functionality by selecting Map Objects Internet Map Server (MO IMS) as Map Server and is implemented using Java as programming language.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.285-294
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• 2003

The request scheduling algorithms being used for the cluster web servers are mostly in two categories : load-balancing and contents-based cache affinity The goal of the load-balancing algorithms is to balance the loads between real servers. On the other hand, contents-based scheduling algorithm exploits the cache affinity in a way that the same type of requests are to be directed to a dedicated real server allowing load imbalance. So the performance comparison of the two algorithms is necessary, nevertheless the related experiment results are not much suggested. In this paper, performance evaluations have been done to compare the performance of the two scheduling algorithms. To accomplish this, we first implement a linux cluster web server, and then present the performance measurement results. The main contribution of this paper is to help the cluster web server administrators to select an algorithm fitting in with their circumstances from the two algorithms.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.892-898
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• 2007

This study aims to implement an efficient process management system for small and medium sized(local) construction companies and a performance management system for the Korean construction industry. The process management system by Lean Construction is Web 2.0 platform-based and creates clusters with numerous general contractors and sub-contractors, which will enable mutually organic process management. Plus, this system will enable them to compare project performance management by analyzing it during or after a project by collecting and accumulating lots of data occurring in pursuit of a project. These performance management cases will be of help in process planning during similar upcoming projects. This study is expected to somewhat reduce the burden of implementing a complicated process management protocol and system that Korean small and medium sized (local) construction companies experience with their web-based process management, and is supposed to realize accurate performance management with highly reliable data which are significantly accumulated within the database.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.65-68
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• 2003

In this paper, we consider issues related to the autonomous management of a server cluster Server clustering technique is widely used for high available Internet servers such as a web server, because it provides very scalable and reliable service. However, it is very burden-some to manage the cluster system. For instance, installation or configuration of a new node requires skilled administrators. Also, when a node is failed, it should be recognized and recovered by a human. The management complexity gets higher while increasing the number of machines for higher throughput. Here, we are going to alleviate the management complexity by building an autonomous cluster server with Jini $_{TM}$ technology from Sun Microsystems.