• The Journal of Society for e-Business Studies
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• v.15 no.2
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• pp.19-35
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• 2010

In response to an increased need, various methods for ontology modularization have been proposed. However, few studies have focused on evaluative methods for ontology modules. In this study, we devise novel metrics to measure ontology modularity. To evaluate the ontology modules, we introduce cohesion and coupling based on the theory of software metrics. A cohesion metric and two coupling metrics were used to measure cohesion and coupling for ontology modules. These metrics were also used to check consistency between the ontology modules and the original ontology. The new metrics support a more detailed relationship between classes in ontology modules. We validate the proposed metrics using the well known verification framework and perform the empirical experiments to complement previous investigations. This study offers ontology engineers valuable criteria with which to select and use ontology modules and modularization techniques.

• Journal of Intelligence and Information Systems
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• v.14 no.4
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• pp.19-30
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• 2008

Semantic heterogeneity should be overcome to support automated information sharing process between information systems in ontology-based distributed environments. To do so, traditional approaches have been based on explicit mapping between ontologies from human experts of the domain. However, the manual tasks are very expensive, so that it is difficult to obtain ontology mappings between all possible pairs of information systems. Thereby, in this paper, we propose a system to make the existing mapping information sharable and exchangeable. It means that the proposed system can collect the existing mapping information and aggregate them. Consequently, we can estimate the ontology mappings in an indirect manner. In particular, this paper focuses on query propagation on the distributed networks. Once we have the indirect mapping between systems, the queries can be efficiently transformed to automatically exchange knowledge between heterogeneous information systems.

• The Journal of Society for e-Business Studies
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• v.13 no.3
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• pp.85-101
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• 2008

The semantic web is taken as next generation standards of information exchange on the internet to overcome the limitations of the current web. To utilize the information on the semantic web, tools are required the functionality of query search and reasoning for the ontology. However, most of semantic web management tools cannot efficiently support the search for the complex query because they apply Triple-based storage structure about RDF metadata. We design the storage structure of the ontology in corresponding with the structure of ontology data and develop the search system(SMART-DLTriple) to support complex query search efficiently in this research. The performance of the system using new storage structure is evaluated to compare with the popular semantic web management systems. The proposed method and system make a contribution to enhancement of a practical ontology reasoning systems due to improved performance of the ontology search.

• Journal of KIISE:Databases
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• v.35 no.1
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• pp.29-43
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• 2008

Although RDF ontologies might be expressed in XML tree model, existing methods for protection of XML documents are not suitable for securing RDF ontologies. The graph style and inference feature of RDF demands a new security model development. Driven by this goal, this paper proposes a new query-oriented model for the RDF ontology access control. The proposed model rewrites a user query using a three-layered ontology view. The proposal resolves the problem that the existing approaches should generate inference models depending on inference rules. Accessible ontology concepts and instances which a user can visit are defined as ontology views, and the inference view defined for controling an inference query enables a controlled inference capability for the user. This paper defines the three-layered view and describes algorithms for query rewriting according to the views. An implemented prototype with its system architecture is shown. Finally, the experiment and comparative evaluation result of the proposal and the previous approach is described.

• Journal of the Korea Society of Computer and Information
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• v.20 no.3
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• pp.9-17
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• 2015

The ISO 26262 standard requires a preliminary hazard analysis and risk assesment early in the development for automotive system. This is a first step for the development of an automotive system to determine the necessary safety measures to be implemented for a certain function. In this paper, we propose an ontology-based hazard analysis and risk assessment method for automotive functional safety. We use ontology to model the hazard and SWRL(Semantic Web Language) to describe risk analysis. The applicability of the proposed method is evaluated by the case study of an ESCL(electronic steering column lock) system. The result show that ontology deduction is useful for improving consistency and accuracy of hazard analysis and risk assessment.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.11a
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• pp.457-462
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• 2007

시멘틱 웹에서의 온톨로지는 특정 영역의 설명을 위해 공유할 개념화된 명세란 정의로 널리 알려져 있으며, 시멘틱웹의 중요한 요소기술이다. 온톨로지는 특정 도메인에 대한 정보를 기술하는데, 이러한 온톨로지를 매핑할 경우 많은 양의 정보를 통합관리하거나, 상호호환성을 이룰 수 있다. 여러 온톨로지 매핑 방법론의 성능을 평가하는 수단 중 f-measure란 것이 있는다. f-measure의 값은 정확도(precision)과 응답률(recall)에 의해서 결정된다. 정확도와 응답률이 변화함에 따라 f-measure 값도 자연히 변하기 때문에, 높은 f-measure 값을 구하기 위해서는 정확도와 응답률의 밸런스를 조정할 필요가 있다. 본 논문에서는 높은 f-measure값을 얻을 수 있는 정확도와 재현률을 구하는 방법을 휴리스틱적 방법을 통하여 알아보고자 한다.

• Journal of the Korean Society for information Management
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• v.24 no.3
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• pp.119-147
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• 2007

Actually a diffusion of a semantic web application and utilization are situations insufficient extremely. Technology most important in semantic web application is construction of the ontology which contents itself with characteristics of semantic web. Proposed a suitable a method of building web ontology for characteristics or semantic web and web ontology as we compared the existing ontology construction ana ontology construction techniques proposed for web ontology construction, and we analyzed. And modeling old ontology to bases to description logic and the any axiom rule that used an expression way of SWRL, and established inference-based web ontology according to proposed ways. Verified performance of ontology established through ontology inference experiment. Also established an web ontology-based intelligence image retrieval system, to experiment systems for performance evaluation of established web ontology, and present an example of implementation of a semantic web application and utilization. Demonstrated excellence of a semantic web application to be based on ontology through inference experiment of an experiment system.

• Journal of Intelligence and Information Systems
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• v.13 no.4
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• pp.91-104
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• 2007

Ontology matching technique is one of the most important techniques in the Semantic Web as well as in other areas. Ontology matching algorithm takes two ontologies as input, and finds out the matching relations between the two ontologies by using some parameters in the matching process. Ontology matching is very useful in various areas such as the integration of large-scale ontologies, the implementation of intelligent unified search, and the share of domain knowledge for various applications. In general cases, the performance of ontology matching is estimated by measuring the matching results such as precision and recall regardless of the requirements that came from the matching environment. Therefore, most research focuses on controlling parameters for the optimization of precision and recall separately. In this paper, we focused on the harmony of precision and recall rather than independent performance of each. The purpose of this paper is to propose a methodology that determines parameters for the desired ratio of precision and recall that is appropriate for the requirements of the matching environment.

• Journal of KIISE:Databases
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• v.35 no.6
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• pp.505-517
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• 2008

This paper proposes a rewriting algorithm of OWL-DL ontology query in SPARQL. Currently, to obtain inference results of given SPARQL queries, Web ontology repositories construct inference ontology models and match the SPARQL queries with the models. However, an inference model requires much larger space than its original base model, and reusability of the model is not available for other inferrable SPARQL queries. Therefore, the aforementioned approach is not suitable for large scale SPARQL query processing. To resolve tills issue, this paper proposes a novel SPARQL query rewriting algorithm that can obtain results by rewriting SPARQL queries and accomplishing query operations against the base ontology model. To achieve this goal, we first define OWL-DL inference rules and apply them on rewriting graph pattern in queries. The paper categorizes the inference rules and discusses on how these rules affect the query rewriting. To show the advantages of our proposal, a prototype system based on lena is implemented. For comparative evaluation, we conduct an experiment with a set of test queries and compare of our proposal with the previous approach. The evaluation result showed the proposed algorithm supports an improved performance in efficiency of the inferrable SPARQL query processing without loss of completeness and soundness.

• 한국IT서비스학회:학술대회논문집
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• 2009.05a
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• pp.393-396
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• 2009

기존의 웹을 확장한 시맨틱 웹의 등장으로 웹 온톨로지의 구축이 중요시 되고 있다. 이로 인하여 현재 웹 온톨로지의 관리 및 활용을 위한 편집기, 웹 온톨로지 기술언어, 저장소 및 추론 엔진 등 다양한 기술 및 시스템들이 개발되어 웹 온톨로지의 구축이 용이해졌다. 이제는 구축된 웹 온톨로지를 응용 시스템에 활용하기 위한 웹 온톨로지 클래스에 대한 인스턴스를 풍부하게 할 수 있는 웹 온톨로지의 확장에 대한 연구가 요구된다. 웹 온톨로지의 확장을 위해서는 먼저 웹 온톨로지를 보다 정확하게 정의해야 하며 웹 온톨로지를 보다 풍부하게 확장할 수 있는 방법이 개발되어야 한다. 웹 온톨로지의 보다 정확한 정의를 위해서는 표준화 된 공통 개념을 이용하여 웹 온톨로지 스키마를 생성해야하며 이를 기반으로 한 웹 온톨로지 간 상호운용성 향상되어야 한다. 따라서 이 논문에서는 표준화 된 공통 개념을 관리하는 메타데이터 레지스트리(Metadata Registry)를 기반으로 구조화 된 데이터를 이용한 웹 온톨로지의 학습 및 확장 모델을 제안한다. 또한, 제안 모델을 위한 프로토타입을 구현하고 제안 모델의 평가에 대하여 기술한다.