• The Journal of Information Technology and Database
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• v.6 no.2
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• pp.45-57
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• 1999

This paper makes an attempt to find a systematic portion of the database design process, especially using the Entity-Relationship(E-R) model. Basically, we consider three aspects as a systematic portion of the database design process. They are, the strategy that a designer selects to design an E-R diagram, designer's cognitive style, and the knowledge and preference of the database designer. An experiment has been carried out in order to verify the systematic relationship between above-mentioned three aspects and the E-R modeling performance. The target system is a professional baseball system. A normative E-R diagram was constructed based upon 48 E-R diagrams produced during the experiment. The ANOVA process has been used to analyze the results. It has been found that there exist significant differences in query-answering capacity and the completeness of the E-R model among design methods. Individual differences in cognitive styles has not been found to be significantly related to the modeling performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.895-909
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• 2013

Distributed Denial-of-Service (DDoS) attacks towards name servers of the Domain Name System (DNS) have threaten to disrupt this critical service. This paper studies the vulnerability of the cache server to the flooding DNS query traffic. As the resolution service provided by cache server, the incoming DNS requests, even the massive attacking traffic, are maintained in the waiting queue. The sojourn of requests lasts until the corresponding responses are returned from the authoritative server or time out. The victim cache server is thus overloaded by the pounding traffic and thereafter goes down. The impact of such attacks is analyzed via the model of queuing process in both cache server and authoritative server. Some specific limits hold for this practical dual queuing process, such as the limited sojourn time in the queue of cache server and the independence of the two queuing processes. The analytical results are presented to evaluate the impact of DDoS attacks on cache server. Finally, numerical results are provided for further analysis.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.450-455
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• 2005

Effective information "query and retrieval" process is one of the fundamental problems in the field communication and information science and has become especially important due to dramatic increase in magnitude of information to be processed in modern era. Of particular importance at information exchange process, our study focuses on compositions of proper queries and retrieval of rural amenity resources. This particular task has been difficult because the rural amenity resources does not necessarily carry measurable traits and also contains huge amount of data. In this Letter, we propose an alternative approach to the architecture of the resource information system by use of a noble retrieval algorithm based on ontology. Test of efficiency and applicability of this new scheme was conducted, and it showed that this has possibility to be effective information retrieval process of rural amenity resources.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.3
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• pp.246-251
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• 2001

In this paper, we proposed the intelligent navigation agent model for successive electronic commerce system management. Fuzzy theory is very useful method where keywords have vague conditions and system must process that conditions. So, using fuzzy theory, we proposed the model that can process the vague keywords effectively. Through the this, we verified that we can get the more appropriate navigation result than any other crisp retrieval keywords condition.

• Journal of the Korea Society of Computer and Information
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• v.9 no.1
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• pp.31-36
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• 2004

As internet technology has rapidly developed, there have been works for the strategic techniques of the geographic information system integration and component that meet the situation of the variable customer requirement in endless change of execute environment. So there needs a design techniques of spatial data common component that can support technology and Query Processing, and so on. In this thesis, design techniques is proposed to support user-friendly interface and query currently available every place to provide these local-based software development technology. This process was evaluated through an verification test with a widely used development methodology The proposed methods is applied for computation and can reduce software development life cycle.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.5
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• pp.492-506
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• 2009

Index structures that are based on sequence matching for XPath processing such as ViST, PRIX and LCS-TRIM have recently been proposed to reduce the search time of XML documents. However, ViST can cause a lot of unnecessary computation and I/O when processing structural joint queries because its numbering scheme is not optimized. PRIX and LCS-TRIM require much processing time for matching XML data trees and queries. In this paper, we propose a novel index structure that solves the problems of ViST and improves the performance of PRIX and LCS-TRIM. Our index structure provides the minimum sequence matching scheme to efficiently process structural queries. Finally, to verify the superiority of the proposed index structure with the minimum sequence matching scheme, we compare our index structure with ViST, PRIX and LCS-TRIM in terms of query processing of a single path or of a branching path including wild-cards ('*' and '//' ).

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.109-119
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• 1999

As the importance and utilization of multimedia data increase, we need to study representing and processing multimedia data within databases. To process multimedia data within databases, we need to precisely model multimedia data, to define data types and operations, and to make up query language supporting them. Therefore, in this paper, we modeled multimedia data using OMT so that we can support multimedia data within databases. We also propose an extended SQL, called MMSQl, which includes new types for supporting multimedia data types and efficiently make a query. Especially, MMSQL provides a mechanism to express temporal and spatial relationships which exist among objects in a multimedia data (internal) or among several multimedia data (external).

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.1-10
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• 2004

According to the evolution of the Internet and wireless mobile communication technology, techniques for mobile databases and wireless web services are issued for them. Recently, these changes of geographic application environment increase the needs for development of new GIS database system for the web services and embedded system. In this paper, we proposed a Jana-based web database systems that can be used in the web-based GIS and mobile databases. This proposed system has been implemented using the Java to be displayed easily into the portable computing devices and Java-based web application servers and using OpenGIS for web data interoperability. Also, it can efficiently process web-based spatial queries by developing a spatial query processor including schema manager and a spatial object storage module.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2108-2115
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• 2000

The conventional Boolean retrieval systems based on vector spae model can provide the results of retrieval fast, they can't reflect exactly user's retrieval purpose including semantic information. Consequently, the results of retrieval process are very different from those users expected. This fact forces users to waste much time for finding expected documents among retrieved documents. In his paper, we designed a bayesian SOM(Self-Organizing feature Maps) in combination with bayesian statistical method and Kohonen network as a kind of unsupervised learning, then perform classifying documents depending on the semantic similarity to user query in real time. If it is difficult to observe statistical characteristics as there are less than 30 documents for clustering, the number of documents must be increased to at least 50. Also, to give high rank to the documents which is most similar to user query semantically among generalized classifications for generalized clusters, we find the similarity by means of Kohonen centroid of each document classification and adjust the secondary rank depending on the similarity.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.1
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• pp.89-98
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• 2004

Conversational agent is a system that provides users with proper information and maintains the context of dialogue on the natural language. Analyzing and modeling process of user's query is essential to make it more realistic, for which Bayesian network is a promising technique. When experts design the network for a domain, the network is usually very complicated and is hard to be understood. The separation of variables in the domain reduces the size of networks and makes it easy to design the conversational agent. Composing Bayesian network as two stages, we aim to design conversational agent easily and analyze user's query in detail. Also, previous information of dialogue makes it possible to maintain the context of conversation. Actually implementing it for a guide of web pages, we can confirm the usefulness of the proposed architecture for conversational agent.