• Korean Journal of Computational Design and Engineering
• /
• v.3 no.1
• /
• pp.31-39
• /
• 1998

This paper deals with a development of the system that implements a collaborative design environment with some intelligent agents on the m. Intelligent agents can design collaboratively trough an interchange of messages in their special domains. Such a collaborative design of agents is achieved on the WWW. In this paper, we propose special agents named intercessor and DCM (Dynamic Connection Manager) and suggest new connection architecture using these agents in the WWW in order to improve the pre-existed agent connection architecture. The proposed agents are developed using Java language and JATLite API. We apply the these agents to the new architecture and show some possibilities that the agent connection architecture can be extended in the WWW Agents interchange messages with others using KOML (Knowledge Query and Manipulation Language), agent communication protocol and language, and deal with message autonomously according to their rule base. Agents register and connect dynamically trough the intercessor agent, and infer from their.

• Journal of Information Technology Applications and Management
• /
• v.12 no.2
• /
• pp.29-43
• /
• 2005

The paper presents the EBORD (Extended Benchmark for Object-Relational Databases) benchmark, which is an extension of the BORD benchmark for object-relational databases. The EBORD benchmark is developed to evaluate the database common functions that should be supported in modern database systems. Besides the 36 test queries already defined in the BORD benchmark, totally 22 test queries in five categories are newly defined in order to measure the index-relevant performance issues and database import capabilities. The EBORD benchmark also features scalability, use of a synthesized database, and a query-oriented evaluation. In order to show the feasibility of the proposed benchmark, we implement it with two commercial database systems. The experimental results and analyses are also reported.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.2
• /
• pp.315-325
• /
• 1999

Indexing techniques for distributed resources have much effect on an information service system based on distributed environment like digital library. There is a centralized indexing technique, a distributed technique, and a mixed technique for distributed indexing techniques. In this paper, we propose new distributed indexing technique using EIF(extended Inverted File) structure that mix the centralized technique and t도 distributed technique. And we propose management techniques using EIF structure and retrieval technique using EIF structure. This distributed indexing technique proposed is able to fast process retrieval request and reduce network overload and select servers relevant to query terms. This paper investigated performance of a proposed distributed indexing technique.

• The Journal of Korean Association of Computer Education
• /
• v.12 no.4
• /
• pp.57-64
• /
• 2009

Protein structure comparison is a task that requires a lot of computing resources because many atoms in proteins need to be processed. To address the issue, Grid computing environment has been employed for processing time-consuming jobs in a distributed manner. However, controling the Grid computing environment may not be easy for non-experts. In this paper, we present a JXTA-based system for protein structure comparison that can be easily controled by non-experts. To search proteins similar to a query protein, the geometric hashing algorithm that consists of preprocessing and recognition was employed. Experimental results indicate that the system can find the correct protein structure for a given query protein structure and the proposed system can be easily extended to solve the protein docking problem. It is expected that the proposed system can be useful for non-experts, especially users who do not have sophisticated knowledge of distributed systems in general such as college students who major in biology or chemistry.

• Journal of Internet Computing and Services
• /
• v.6 no.3
• /
• pp.55-70
• /
• 2005

In order to provide mobile hosts with multicast service in mobile communication environment, we proposed a multicast mechanism named HXcast++ which is an extended version of the existing Xcast++ with hierarchical architecture, We assured that mobile hosts could get multicast service through an optimal path regardless of their location by making DR(Designated Router) join a group on behalf of the mobile hosts, In this present research we introduced hierarchical architecture in order to reduce the maintenance cost resulting from frequent handoff. We also proposed a GMA (Group Management Agent) based group management mechanism which enables the mobile hosts to join the group without waiting for a new IGMP Membership Query. A fast handoff method with L2 Mobile Trigger was, in this work, employed in order to reduce the amount of the packet loss which occurs as a result of the handoff, We also managed to curtail the packet loss caused by the latency of the group join by using a buffering and forward mechanism.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.1
• /
• pp.14-24
• /
• 2004

Views are essential in providing logical data independence for database systems. Object views in object-oriented/object-relational databases have requirements quite different from those of relational databases due to support for object-oriented concepts. Although many commercial object-oriented/object-relational database systems support object views, implementation techniques have not been discussed sufficiently in the literature. In this paper, we devise a technique for implementing views in object-oriented/object-relational databases and apply it to the ODYSSEUS object-relational database system. We first analyze the requirements of object views. Next, to implement object views, we extend the existing query modification algorithm that has been proposed for implementing views in relational databases. Next, we compare the features of the proposed object view with those of object views in commercial object-relational database systems. It is shown that the proposed object view supports all object-oriented concepts such as object identifiers, inheritance, methods, and composite objects, while existing object views support part of them. Last, we propose detailed techniques for implementing the extended query modification algorithm in the ODYSSEUS object-relational database system.

• Journal of KIISE:Databases
• /
• v.30 no.1
• /
• pp.27-40
• /
• 2003

The inverted index widely used in the existing information retrieval field should be extended for XML documents to support containment queries by XML information retrieval systems. In this paper, we consider that there are two methods in storing the inverted index and processing containment queries for XML documents as the previous work suggested: using a RDBMS or using an inverted lift engine. It has two drawbacks to extend the inverted index in the previous work. One is that using a RDBMS is moth worse in the performance than using an inverted list engine. The other is that when containment queries are processed in a RDBMS, there is an increase in the number of a join operation as the path length of a query increases and a join operation always happens between large fables. In this paper. we extend the inverted index in a different way to solve these problems and show the effectiveness of using a RDBMS.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.1 s.39
• /
• pp.87-96
• /
• 2006

Selectivity estimation is one of the query optimization techniques. It is difficult for the previous selectivity estimation techniques for moving objects to apply the position change of moving objects to synopsis. Therefore, they result in much error when estimating selectivity for queries, because they are based on the extended spatial synopsis which does not consider the property of the moving objects. In order to reduce the estimation error, the existing techniques should often rebuild the synopsis. Consequently problem occurs, that is, the whole database should be read frequently. In this paper, we proposed a moving object histogram method based on quad tree to develop a selectivity estimation technique for moving object queries. We then analyzed the performance of the proposed method through the implementation and evaluation of the proposed method. Our method can be used in various location management systems such as vehicle location tracking systems, location based services, telematics services, emergency rescue service, etc in which the location information of moving objects changes over time.

• Journal of Korea Multimedia Society
• /
• v.9 no.12
• /
• pp.1529-1541
• /
• 2006

Moving objects have been widely employed in traffic and logistic applications. Spatio-temporal aggregations mainly describe the moving object's behavior in the spatial data warehouse. The previous works usually express the object moving in some certain region, but ignore the object often moving along as the trajectory. Other researches focus on aggregation and comparison of trajectories. They divide the spatial region into units which records how many times the trajectories passed in the unit time. It not only makes the storage space quite ineffective, but also can not maintain spatial data property. In this paper, a spatio-temporal aggregation index structure for moving object trajectory in constrained network is proposed. An extended B-tree node contains the information of timestamp and the aggregation values of trajectories with two directions. The network is divided into segments and then the spatial index structure is constructed. There are the leaf node and the non leaf node. The leaf node contains the aggregation values of moving object's trajectory and the pointer to the extended B-tree. And the non leaf node contains the MBR(Minimum Bounding Rectangle), MSAV(Max Segment Aggregation Value) and its segment ID. The proposed technique overcomes previous problems efficiently and makes it practicable finding moving object trajectory in the time interval. It improves the shortcoming of R-tree, and makes some improvement to the spatio-temporal data in query processing and storage.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.3 no.4
• /
• pp.313-318
• /
• 2002

The Integration of agent technology and security technology is needed to many application areas like electronic commerce. This paper suggests a model of extended multi-agent engine which supports privacy, integrity, authentication and non-repudiation on agent communication. Each agent which is developed with the agent engine is composed of agent engine layer and agent application layer. We describe and use the concepts self-to-self messages, secure communication channel, and distinction of KQML messages in agent application layer and messages in agent engine layer. The suggested agent engine provides an agent communication language which is extended to enable secure communication between agents without any modifications or restrictions to content layer and message layer of KQML. Also, in the model of our multi-agent engine, secure communication is expressed and processed transparently on the agent communication language.