• Journal of KIISE:Databases
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• v.35 no.3
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• pp.243-256
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• 2008

With rapid growth of Internet, the amount of information in the Web is increasing exponentially. However, information on the current Web is understandable only for human, and thus it makes the exact information retrieval difficult. For solving this problem, the Semantic Web is suggested and we must use ontology languages that can endow data to semantics for implementing it. One of the representative ontology languages is OWL(Web Ontology Language) adopted as a recommendation by the World-Wide Web Consortium. OWL has richer expression power and formal semantics than other ontology languages such as RDF and RDF-S. In addition, OWL includes hierarchical structure information between classes or properties. Therefore, an efficient OWL storage model considering hierarchical structure for effective information retrieval on the Semantic Web is required. In this paper, we suggest the XPOS(XPath-based OWL Storage) model including hierarchy information between classes or properties as XPath form and enabling intuitive and effective information retrieval. Also, we show the comparative evaluation results on the performance of XPOS model, Sesame, and the XML storage-based storage model regarding query processing.

• Journal of KIISE:Databases
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• v.33 no.4
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• pp.363-371
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• 2006

In spite of computer's development, the present state of a lot of electronic documents overflowed it's going to be more difficult to get appropriate information. Therefore it's more important to get meaningful information than to focus on the speed of processing. Semantic web enables and intelligent processing by adding semantic meta data on your web documents. Also as the semantic web grows, the knowledge resource is more important. In this paper, we propose a RDF storage system using relational database model aimed at intelligent processing by adding semantic meta data on your web documents, also a query processor aimed at query processing through the storage system. By using relational model, we could overcome a weakness of object or memory model.

• Journal of KIISE:Databases
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• v.31 no.2
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• pp.99-107
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• 2004

Education and training are expected to change dramatically due to the combined impact of the Internet, database, and multimedia technologies However, the distance learning is often impeded by the lack of effective tools and system to manage and retrieve the lecture contents effectively. This paper introduces a prototype system called COVA that enables remote users to access specific parts of interest by contents from a large lecture database. COVA includes several novel techniques to achieve the content-based lecture retrieval in distance teaming: (1) The XML-based semistructured model to represent lecture contents; (2) The technique to build structural summaries, i.e., schemas, of XML lecture databases; (3) Index structures to speed up the search to find appropriate lecture contents.

• Journal of KIISE:Databases
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• v.35 no.2
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• pp.155-168
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• 2008

This paper proposes a relational security model-based RDF Web ontology access control model. The Semantic Web is recognized as a next generation Web and RDF is a Web ontology description language to realize the Semantic Web. Much effort has been on the RDF and most research has been focused on the editor, storage, and inference engine. However, little attention has been given to the security issue, which is one of the most important requirements for information systems. Even though several researches on the RDF ontology security have been proposed, they have overhead to load all relevant data to memory and neglect the situation that most ontology storages are being developed based on relational database. This paper proposes a novel RDF Web ontology security model based on relational database to resolve the issues. The proposed security model provides high practicality and usability, and also we can easily make it stable owing to the stability of the relational database security model.

• Journal of KIISE:Software and Applications
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• v.30 no.3_4
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• pp.326-338
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• 2003

The objective of a neural network design and model selection is to construct an optimal network with a good generalization performance. However, training data include noises, and the number of training data is not sufficient, which results in the difference between the true probability distribution and the empirical one. The difference makes the teaming parameters to over-fit only to training data and to deviate from the true distribution of data, which is called the overfitting phenomenon. The overfilled neural network shows good approximations for the training data, but gives bad predictions to untrained new data. As the complexity of the neural network increases, this overfitting phenomenon also becomes more severe. In this paper, by taking statistical viewpoint, we proposed an integrative process for neural network design and model selection method in order to improve generalization performance. At first, by using the natural gradient learning with adaptive regularization, we try to obtain optimal parameters that are not overfilled to training data with fast convergence. By adopting the natural pruning to the obtained optimal parameters, we generate several candidates of network model with different sizes. Finally, we select an optimal model among candidate models based on the Bayesian Information Criteria. Through the computer simulation on benchmark problems, we confirm the generalization and structure optimization performance of the proposed integrative process of teaming and model selection.

• 한국공간정보시스템학회:학술대회논문집
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• 1999.06a
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• pp.149-156
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• 1999

지형정보시스템(이하 GIS)에 있어서 공간 데이타베이스의 구축은 GIS 전체 구축비용의 많은 부분을 차지하며 막대한 시간과 비용이 소요되는 과정이다. 수치지도를 이용한 공간 데이타베이스 구축은 데이타 수집비용의 절감이라는 측면에서 점차 그 유용성이 증대되고 있지만 경계선 불일치, 객체의 불연속성과 같은 새로운 문제점들이 나타나게 되어 공간 데이터베이스를 생성하기 전에 수치지도에 대한 수정 및 편집작업이 수행되어야 한다. 이 논문에서는 클라이언트-서버 환경에서 여러 클라이언트가 수치지도에 대하여 동시에 수정작업을 하기 위해 영역 잠금(region lock)을 이용한 협동 트랜잭션 모델을 제시한다. 그리고 경계선 작업 시에 클라이언트간의 협동작업을 위한 메시지 전파 프로토콜을 제시한다.

• Journal of KIISE:Databases
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• v.35 no.1
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• pp.44-53
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• 2008

According to the widespread use of ontology-based applications, it is critical to efficiently store and process semantic information. Even though several related systems have been developed, they have some limitations in perspectives of the volume of target semantic data, the performance of semantic query processing, and the semantic data maintenance. In this paper we propose the OWL-aware relational model for the ontology management system and SQL-based semantic query processing mechanism. Also, to verify the query processing performance, we show that the proposed query professing mechanism is more efficient than sesame.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1994.11a
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• pp.223-232
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• 1994

객체지향 데이타베이스 시스템에서 무결성은 중요한 개념이다. 이 무결성이 객체의 내부 메소드로 정의되고 구현하면 응용에서의 무결성 의미 파악이 어렵고, 또한 객체의 기본적인 메소드와 함께 모형화되기 때문에 데이타베이스 설계 작업이 복잡해진다. 본 논문에서는 무결성을 매소드로 처리할 때의 문제점을 극복하기 위하여 동적 데이타베이스의 동적 규칙을 이용하여 무결성 제약조건을 정의하고 유지시키는 객체지향 데이타베이스에서 무결성과 임무 분리를 유지시키는 기립을 제안한다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.9 no.2
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• pp.139-149
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• 1991

In general, Digital Elevation Models(DEM) are constructed in a grid format for this form is advantageous to capture data automatically and is easy to manipulate. But, grid DEM requires vast volumes of data to represent terrain features finely and accurately as its data is sampled in a regular space. This paper aims at constructing compact DEM by selecting the significant points from grid DEM which affect well the terrain features. For the purpose, the significant points is detected by the high-pass filtering using Laplacian operator and gradient operator. The results of this study show that the Laplacian operator is more efficient than the gradient operator in selecting the significant points for compact DEM.

• Proceedings of the Korean Society for Information Management Conference
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• 1994.12a
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• pp.29-32
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• 1994

과거 실세계 정보를 처리하기 위한 방법으로는 관계형데이타베이스, 객체지향데이타베이스. 지식베이스시스템 등이 연구되었다. 이들 방법은 제한된 정보표현 및 정보의 운영 및 접근방법 등의 문제점을 갖는다. 정보의 구조화는 정보의 의미를 분석하고 정보의 특성에 적합한 융통성 있는 정보모델을 필요로 한다. 본 논문에서는 방대한 양의 정보처리 및 다양한 형태의 표현, 동적 변환 등의 정보특성을 효율적으로 처리하기 위한 정보모델로 의미구조그래프를 사용하여 기존 시스템의 문제점을 해결하기 위한 방법을 제안한다. 의미구조그래프를 사용한 정보구조화는 정보의미를 분석할 수 있으며, 정보의 표현의 융통성을 제공한다. 의미구조그래프는 노드와 링크를 갖는 확장된 하이퍼그래프를 사용하였으며, 정보구조화를 위한 대상데이타로 문화예술 분야의 관련 정보를 실험하였다.