• Journal of KIISE:Databases
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• v.29 no.5
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• pp.347-357
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• 2002

Graphs have provided a powerful methodology to solve a lot of real-world problems, and therefore there have been many proposals on the graph representations and algorithms. But, because most of them considered only memory-based graphs, there are still difficulties to apply them to large-scale problems. To cope with the difficulties, this paper proposes a graph representation and graph algorithms based on the well-developed relational database theory. Graphs are represented in the form of relations which can be visualized as relational tables. Each vertex and edge of a graph is represented as a tuple in the tables. Graph algorithms are also defined in terms of relational algebraic operations such as projection, selection, and join. They can be implemented with the database language such as SQL. We also developed a library of basic graph operations for the management of graphs and the development of graph applications. This database approach provides an efficient methodology to deal with very large- scale graphs, and the graph library supports the development of graph applications. Furthermore, it has many advantages such as the concurrent graph sharing among users by virtue of the capability of database.

• Journal of KIISE:Software and Applications
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• v.26 no.8
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• pp.939-954
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• 1999

데이타마이닝 분야에서는 대용량의 트랜잭션 데이타베이스와 같은 하나의 데이타베이스로부터 연관 규칙을 찾는 연구가 많이 수행되어왔다. 그러나, 창고형 할인매장이나 백화점 같이 고객 카드를 이용하는 판매점의 등장으로, 단지 트랜잭션에 대한 분석 뿐만이 아니라, 트랜잭션과 고객과의 관계에 대한 분석 또한 요구되고 있다. 즉, 두 개의 데이타베이스로부터 연관 규칙을 찾는 연구가 필요하다. 이 논문에서는 두 데이타베이스 사이에 링크를 생성하여 연관 항목집합을 찾는 알고리즘을 제안한다. 실험 결과, 링크를 이용한 알고리즘은 고객 데이타베이스가 메모리에 거주가능한 크기라면 시간에 따른 분석에 유용함을 보여주었다.Abstract There have been a lot of researches of mining association rules from one database such as transaction database until now. But as the large discount store using customer card emerges, the analysis is not only required about transactions, but also about the relation between transactions and customer data. That is, it is required to search association rules from two databases. This paper proposes an efficient algorithm constructing links from one database to the other. Our experiments show the algorithm using link is useful for temporal analysis of memory-resident customer database.

• Journal of KIISE:Databases
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• v.30 no.5
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• pp.540-551
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• 2003

Recently, several works have been proposed for updating XML documents［l-3] stored in databases. These researches defined update operations and resolved some semantic problems. Because the update operations are usually validated after execution, several conflicts nay occur. For solving these conflicts, XML database systems must be able to validate an update operation immediately according to DTD before the update operation is executed. Furthermore, in many studies for updating, they just validate whole XML documents and can't validate parts of them. If updates are very frequent, validating whole XML documents will cause performance degradation. In this paper, we propose solutions for these two problems. We extract and store DTD information. Then, when an XML document stored in the database is updated, we verifies whether the update is valid or not by using the information. Consequently, XML database systems can always maintain valid XML documents. The validity of update operations is checked immediately before the actual update operation is applied to the database and the validation is performed on only updated parts of an XML document in the database.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.150-160
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• 2000

The currently and most widely used client/server architecture is composed of database servers and clients that include both application and presentation logic. To date, due to the rapid growth in WWW, these client/server applications are implemented using Java language, especially in GUI design at client sides and client/server applications development using JDBC. To develop the applications using JDBC, developers should design database schema, code source code for JDBC connection, design report forms to display selected columns from server-side database. In this paper, we propose a development environment based on JavaBeans component for client/server applications development using JDBC. The proposed environment minimizes manual coding and enables developers to develop client/server applications easily with the designed JavaBeans components and their custom property editor.

• Proceedings of the KSPS conference
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• 1996.02a
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• pp.115-124
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• 1996

우리말의 음성언어학적, 공학적, 의학적 연구를 위해서는 체계적으로 수집, 정리 된 다양한 음성자료가 필수적이다. 본고에서는 음성언어의 연구대상자료인 음성데이타베이스에 관하여 관련분야에서의 구축필요성, 체계적인 구축을 위한 기술적인 고려사항 등에 대하여 논한다. 또한 공학적인 응용을 위해 각 기관별로 구축된 음성DB의 현황을 정리하고, 특히 공동이용을 목적으로 하여 국어공학센터에서 추진중인 음성데이타베이스의 구축현황을 상세히 소개한다.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.261-273
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• 2004

Advances in information and communication technologies have been creating new classes of applications in the area of databases. For example, in moving object databases, which track positions of a lot of objects, or stream databases, which process data streams from a lot of sensors, data Processed in such database systems are usually changed very rapidly and continuously. However, traditional database systems have a problem in processing these rapidly and continuously changing data because they suppose that a data item stored in the database remains constant until It is explicitly modified. The problem becomes more serious in the R-tree, which is a typical index structure for multidimensional data, because modifying data in the R-tree can generate cascading node splits or merges. To process frequent updates more efficiently, we propose a novel update technique for the R-tree, which we call the leaf-update technique. If a new value of a data item lies within the leaf MBR that the data item belongs, the leaf-update technique changes the leaf node only, not whole of the tree. Using this leaf-update manner and the leaf-access hash table for direct access to leaf nodes, the proposed technique can reduce update cost greatly. In addition, the leaf-update technique can be adopted in diverse variants of the R-tree and various applications that use the R-tree since it is based on the R-tree and it guarantees the correctness of the R-tree. In this paper, we prove the effectiveness of the leaf-update techniques theoretically and present experimental results that show that our technique outperforms traditional one.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.2
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• pp.213-225
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• 2003

In multimedia database system, it is very important issue how to query multimedia data and present the result of query. Also, in order to reuse the query result in other applications, multimedia database system must be considered to provide the query result which is more generalized form. In this paper, I propose a presentation model for presenting query result in multimedia database system and MMSQL based on the developed model for processing multimedia database query. This paper includes the design and implementation of MMSQL query processor. MMSQL query processor provides the presentation of query result which is SMIL (Synchronized Multimedia Integration Language) document. Therefore, MMSQL query result in this paper can be use to variant multimedia applications.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.351-360
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• 2002

HyTime(Hypermedia/Time-based Structuring Language), an international standard language to describe hypermedia electronic documents, is used to support the synchronization between various multimedia data for hypermedia applications. To manage the HyTime documents efficiently for shared environment, the logical structure information of them should be managed by database in a systematic way. In this Paper, we design a meta-database schema of HyTime DTDs(Document Type Definition) which define the logical structure of hypermedia documents and show how to manage the meta-database schema for storing the HyTime DTDs in the object-oriented database.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.201-205
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• 2008

The flash memory is widely used as a main storage of embedded devices. It is adopted as a storage of database as growing the capacity of the flash memory. We run TPC-C benchmark on various FTL algorithms. But, the database shows poor performance on flash memory because the characteristic of I/O requests is full random. In this paper, we show the performance of all existing FTL algorithms is very poor. Especially, the FTL algorithm known as good at small mobile equipment shows worst performance. In addition, the chip-inter leaving which is a technique to improve the performance of the flash memory doesn't work well. In this paper, we inform you the reason that we need a new FTL algorithm and the direction for the database in the future.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.255-264
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• 1993

요즈음 구축되는 지식기반시스템은 다목적, 다사용자에 의한 활용 필요성 때문에 지식베이스가 점점 커지고, 축적된 전문지식을 공유할 필요성이 점점 커진다. 따라서, 이렇게 형성된 여러개의 다양한 지식베이스를 지속적으로 관리할 수 있는 메카니즘이 필요하다. 이런 메카니즘의 구축에 객체 지향 데이타베이스 관리시스템의 기술과 지식 기반시스템의 기술이 통합 활용되어야 하기 때문에, 지식베이스의 확장과 응용 영역확대에 따른 데이타, 규칙, 그리고 지식의 공유 및 지속성을 유지하는 한편, 이에 필요한 추론방법의 변화를 분석하여 지식베이스가 분산되어 있더라도 이를 효율적으로 활용할 수 있는 추론엔진을 설계하고, 여러 사용자가 필요한 지식기반시스템을 사용할 수 있도록 지식베이스의 공유를 위한 지속적 관리시스템의 설계를 그 목적으로 한다.