• Journal of KIISE:Databases
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• v.35 no.5
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• pp.447-458
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• 2008

In this paper, we address an efficient processing scheme for k-nearest neighbor queries to retrieve k static objects in road network databases. Existing methods cannot expect a query processing speed-up by index structures in road network databases, since it is impossible to build an index by the network distance, which cannot meet the triangular inequality requirement, essential for index creation, but only possible in a totally ordered set. Thus, these previous methods suffer from a serious performance degradation in query processing. Another method using pre-computed network distances also suffers from a serious storage overhead to maintain a huge amount of pre-computed network distances. To solve these performance and storage problems at the same time, this paper proposes a novel approach that creates an index for moving objects by approximating their network distances and efficiently processes k-nearest neighbor queries by means of the approximate index. For this approach, we proposed a systematic way of mapping each moving object on a road network into the corresponding absolute position in the m-dimensional space. To meet the triangular inequality this paper proposes a new notion of average network distance, and uses FastMap to map moving objects to their corresponding points in the m-dimensional space. After then, we present an approximate indexing algorithm to build an R*-tree, a multidimensional index, on the m-dimensional points of moving objects. The proposed scheme presents a query processing algorithm capable of efficiently evaluating k-nearest neighbor queries by finding k-nearest points (i.e., k-nearest moving objects) from the m-dimensional index. Finally, a variety of extensive experiments verifies the performance enhancement of the proposed approach by performing especially for the real-life road network databases.

• Journal of KIISE:Databases
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• v.33 no.4
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• pp.396-408
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• 2006

Moving object databases manage a large amount of past location data which are accumulated as the time goes. To retrieve fast the past location of moving objects, we need index structures which consider features of moving objects. The KDB-tree has a good performance in processing range queries. Although we use the KDB-tree as an index structure for moving object databases, there has an over-split problem in the spatial domain since the feature of moving object databases is to increase the time domain. Because the over-split problem reduces spatial regions in the MBR of nodes inverse proportion to the number of splits, there has a problem that the cost for processing spatial-temporal range queries is increased. In this paper, we propose the dynamic split strategy of the KDB-tree to process efficiently the spatial-temporal range queries. The dynamic split strategy uses the space priority splitting method for choosing the split domain, the recent time splitting policy for splitting a point page to maximize the space utilization, and the last division policy for splitting a region page. We compare the performance of proposed dynamic split strategy with the 3DR-tree, the MV3R-tree, and the KDB-tree. In our performance study for range queries, the number of node access in the MKDB-tree is average 30% less than compared index structures.

• Proceedings of the Korean Society for Information Management Conference
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• 1999.08a
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• pp.157-162
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• 1999

본 연구는 분산환경에서 이용자가 다수의 데이터베이스를 개별적으로 검색할 매와 통합적으로 검색할 때에 유용성과 이용자선호도, 이용자 만족도를 비교 분석하였다. 본 연구에는 럿거스대학 School of Communication, Information, and Library Studies에 재학중인 28명의 대학원생들이 참가하였다. 두 시스템에 대한 이용자선호도와 만족도에는 통계적으로 유의한 차이가 있는 것으로 나타났다. 즉, 많은 참가자들이 통합인터페이스보다 분리인터페이스를 선호하였고, 분리인터페이스의 검색결과에 더 만족하였다. 통합인터페이스의 편리함과 능률성에도 불구하고 참가자들이 분리인터페이스를 선호한 주된 이유중의 하나는 데이터베이스를 이용자 스스로 선택하고 통제할 수 있기 때문인 것으로 나타났다.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.457-463
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• 2000

Recently, statistical analysis tools have been changed to the applications on the World Wide Web that access data stored in databases. On-line analytical processing(OLAP) is a class of technologies that give users statistical information with multidimensional views of data in databases. In this paper, we introduce the concept and requisites of OLAP system, and we propose some research issues.

• Journal of the Korea Computer Industry Society
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• v.5 no.5
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• pp.699-710
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• 2004

It is one of important techniques to protect illegal uses and forgeries for text databases when the internet has become widsepread. Lots of studies and system developments has been progressed in order to protect text databases, important documents of the companies, and blueprints of the research institutes. Given this project securing the KISTI (Korea Institute of Science and Teschnology Information) digital contents, we are to design a watermaking and fingerprinting system protecting document images, and a agent notifying the traitors' location.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.333-337
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• 2003

Electronic journals and commercial web databases are major parts of scholarly contents. In this study we investigated the current situation for both of them and the ways of integrated operation. Also we studied the integration scheme with paper resources and usage when we establish future information contents and resources development action plan.

• Journal of Korean Library and Information Science Society
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• v.30 no.3
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• pp.405-426
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• 1999

Academic societies in the field of science and technology are major producers of domestic research information. These information are very important sources to researchers, students and so on. KORDIC built an integrated information system which facilitates the progress of building databases and promotes users easy access to databases. In order to build efficient society research information system, we investigated former cases and analyzed requirement of each society. We identified principal information sources and built an integrated information service system using internet homepage and information retrieval system(KRISTAL-II). In the future we will expand participating societies and focus on text-based information.

• Proceedings of the Korean Society for Information Management Conference
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• 1996.08a
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• pp.11-14
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• 1996

The purpose of this study is to verify the hypothesis that the end-user's standards of the selection over retrieved documents affect the selecting of relevant documents after online bibliographic databases searching. To achieve the above-mentioned purpose, online-questionnaires were distributed, via e-mail, to end-users of using online bibliographic databases.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1148-1152
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• 1987

This paper analyzes the statistical and scientific entity-aspect model for statistical and scientific databases(SSDB's). The statistical and scientific entity-aspect model(SEAM) is defined an example of the application of the statistical and scientific entity-aspect model is represented. Finally, the statistical and scientific entity-aspect model as a design tool for SSDB is evaluated and the further research areas are suggested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.2
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• pp.215-224
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• 1997

This paper addresses the vertical class fragmentation in distributed object-oriented databases. In the proposed vertical fragmentation, after producing the attribute fragment by partitioning attributes, then the method fragment is produced by gathering methods referring the attribute in each fragment. For partitioning attributes, we define query access matrix(QAM) and method access matrix(MAM) to express attributes that method refers, and extend QAM, MAM and attribute usage matrix(AUM) to universal class environment for representing relationship among other classes through class hierarchy and class composite hierarchy.