• Journal of Korea Society of Industrial Information Systems
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• v.17 no.5
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• pp.19-28
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• 2012

Recently a grid and cloud computing collaboration have become a social issue. These collaborative network system, the P2P system based on this system. Distingui shed from the client/server systems, P2P systems in order to exchange information, its purpose and functions are divided according to the morphological Category. In accordance with the purposes and functions of information and data retrieval, remote program control and integration services for the offers. Most P2P systems client/server scalability, and management takes the form, but to overcome the disadvantages in terms of applying the mixed-mode system is increasing. And recently the distributed computing aspects of the service to users in order to provide suitable to accommodate the diverse needs of various types of mobile agent technology is needed. In this paper, as required by the mobile agent access to a remote resource access control and agent for the execution and management capabilities and improve the reliability of the mobile agent system designed to suggest.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1567-1574
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• 2012

Since a migration method of the mobile agent is a factor that affects the overall performance of the entire distributed system, it is necessary to find efficient migration methods of the mobile agent within the sensor network and to collect and store data related to various components(server, sink and sensor node) of the sensor network, thereby providing consistent naming services. Accordingly, this paper presents design and implementation of MetaTable that is divided into MetaData where information on the sensor data server is stored and SubMetaData where various types of information on sink nodes and data on sensor nodes connected with the sink nodes is stored. Moreover, the paper also presented the implementation of forward migration of an active rule mobile agent applying the naming method based on RMI that used the meta_table and proposed the possibility of constructing efficient sensor network application environment. In this paper, for registration, release and retrieval methods suitable for new sensor network environment, we designed and implemented the naming agent by applying J2EE model based on RMI-IIOP(Internet Inter-ORB Protocol) technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1597-1603
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• 2004

Recently many corporations are introducing web services which supports mutual smooth information exchange without depending on platform or programming language and new distributed computing environment based on U standard technology and internet standard protocol such as HTTP. However they are suffering difficulty in interoperability because of the problem of version inconsistency of standards supported by platforms that each vender offers. To solve these interoperability problem, although WS-I is progressing a consecutive standardization work by method of that offer Basic Profile and Usage Scenario, it is in the state that the domestic research connected with this is not sufficient yet. Accordingly, this treatise constructed interoperability Test framework by developing web services on the basis of different platform from books information retrieval services that can easily be come with and simulated and verified the interoperability by applying WS-I Basic Profile.

• Journal of Internet Computing and Services
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• v.3 no.1
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• pp.81-90
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• 2002

Large-scale distributed applications based on Internet and client/server applications have to deal with series of problems. Load balancing, unpredictable communication delays, and networking failures can be the example of the series of problems. Therefore. sophisticated applications such as teleconferencing, video-on-demand, and concurrent software engineering require an abstracted group communication, CORBA does not address these paradigms adequately. It mainly deals with point-to-point communication and does not support the development of reliable applications that include predictable behavior in distributed systems. In this paper, we present our design, implementation and performance analysis of the group communication using the CORBA-ORB. JAVA-RML and Socket based on distributed computing Performance analysis will be estimated latency-lime according to object increment, in case of group communication using ORB of CORBA the average is 14.5172msec, in case of group communication using RMI of Java the average is 21.4085msec, in case of group communication using socket the average is becoming 18.0714msec. Each group communication using multicast and UDP can be estimated 0.2735msec and 0.2157msec. The performance of the CORBA-ORB group communication is increased because of the increased object by the result of this research. This study can be applied to the fault-tolerant client/server system, group-ware. text retrieval system, and financial information systems.

• Journal of KIISE:Software and Applications
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• v.31 no.12
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• pp.1637-1648
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• 2004

When digital libraries are developed by the traditional client/sever system using a single agent on the distributed environment, several problems occur. First, as the search method is one dimensional, the search results have little relationship to each other. Second, the results do not reflect the user's preference. Third, whenever a client connects to the server, users have to receive the certification. Therefore, the retrieval of documents is less efficient causing dissatisfaction with the system. I propose a new platform of mobile multiagents for a personal digital library to overcome these problems. To develop this new platform I combine the existing DECAF multiagents platform with the Voyager mobile ORB and propose a new negotiation algorithm and scheduling algorithm. Although there has been some research for a personal digital library, I believe there have been few studies on their integration and systemization. For searches of related information, the proposed platform could increase the relationship of search results by subdividing the related documents, which are classified by a supervised neural network. For the user's preference, as some modular clients are applied to a neural network, the search results are optimized. By combining a mobile and multiagents platform a new mobile, multiagents platform is developed in order to decrease a network burden. Furthermore, a new negotiation algorithm and a scheduling algorithm are activated for the effectiveness of PDS. The results of the simulation demonstrate that as the number of servers and agents are increased, the search time for PDS decreases while the degree of the user's satisfaction is four times greater than with the C/S model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1022-1036
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• 2004

In mobile cellular network the ever-changing location of a mobile host necessitates the continuous tracking of its current position and efficient management of location information. A database called Home Location Register(HLR) plays a major role in location management in this distributed environment, providing table management, index management, and backup management facilities. The objectives of this paper are to identify the p개blems of the current HLR system through rigorous analysis, to suggest solutions to them, and to propose a new architecture for the HLR system. In the HLR system, a main memory database system is used to provide real-time accesses and updates of subscriber's information. Thus it is suggested that the improvement bemade to support better real-time facilities, to manage subscriber's information more reliably, and to accommodate more subscribers. In this paper, I propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the T-tree index method. Insertion md deletion overhead of the chained bucket hashing method is less than that of modified linear hashing method. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. Performance analysis has been performed to evaluate the proposed techniques based on a system with subscribers. The results show that, in comparison with the current techniques, the memory requirement is reduced by more than 62%,directory operations, and backup operation by more than 80%.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.427-433
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• 2004

Most information providers are offering integrated retrieval service based on the bibliographic metadata and schema corresponding to each type of document which are developed in a distributed and independent way. However, it is difficult to maintain the relational consistency of those single heterogeneous databases even though they obey the metadata standard like MARC or MODS. It is the main reason that those standards are restricted to present the general property of document regardless of its type and not to applied to define the relationship of document types. Therefore, It is necessary to define a comprehensive meta model to associate the related databases in a systematic way so that the semantically common part of them can be easily shared and reused without any additional effort like conversion or mapping. In this paper, we first outline the document types for designing meta model by the empirical analysis of various data schema of main information providers. We propose then data element definition, metadata model and modularized XML DTD which support the efficient and consistent management of multiple ducument types.

• Journal of KIISE:Databases
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• v.30 no.5
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• pp.464-475
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• 2003

few sample objects and compressed histogram information of image databases. The histogram information is used to estimate the selectivity of spherical range queries and a small number of sample objects is used to compensate the selectivity error due to the difference of the similarity measures between meta server and local image databases. An extensive experiment on a large number of image data demonstrates that our proposed method performs well in the distributed heterogeneous environment.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.614-620
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• 2003

As the proliferation of Internet, mobile agent related technologies are examined for possible growth and evolution. In information retrieval, network and distributed system management, and electronic commerce, mobile agent is more flexible than the traditional communication paradigm. Despite the performance benefits, mobile agent is not used widely in the market because it is very vulnerable to a variety of attacks. In many studies related the security vulnerability for a mobile agent, the high security causes the performance to degrade. In this paper, we propose and evaluate the efficient security model for mobile agent using TDGM(Trusted Domain & Guide Manager), which provides three kinds of services : the trusted domain management, the security service and the travel plan guide. The result clearly shows that this model provides high security and minimizes the performance degradation.

• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.93-100
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• 2003

With the advent of distributed computing and Web service technologies, lots of users have been requiring services that can conveniently obtain and/or support well-assembled information based on Web. For this reason, we are to construct Automatic Linking Support Systems for generating Web-based integrated information and supporting retrieval information according to user's various requirements. Our system organization is based on client/server system. A server environment consisted of automatic linking engine that can provide lexical analyzing, query processing and integrated document generating functions, and databases that are made of dictionaries, image and URL contents. Also, client environments consisted of Web editor that can generate integrated documents and Web helper that can retrieve them via automatic linking engine and databases. For client's user-friendly interfaces, web editor and helper programs can directly execute by down leading from a server without setup them before inside clients. For reducing server's overheads, Parts of server's executing modules are distributed to clients on which they can be executing. As an implementation of our system, we use the JDK 1.3, SWING for user interfaces like Web editor and helper, RMI mechanism for interaction between clients and a server, and SQL server 7.0 for database development, respectively. Finally, we showed the access procedures of automatic document linking engine and databases from Web editor or Web helper, and results appearing on their screens.