• 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.

• Composites Research
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• v.37 no.1
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• pp.32-39
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• 2024

Solid-state hydrogen storage is gaining prominence as a crucial subject in advancing the hydrogen-based economy and innovating energy storage technology. This storage method shows superior characteristics in terms of safety, storage, and operational efficiency compared to existing methods such as compression and liquefied hydrogen storage. In this study, we aim to evaluate the solid hydrogen storage performance on the nanotube surface by various structural design factors. This is accomplished through molecular dynamics simulations (MD) with the aim of uncovering the underlying ism. The simulation incorporates diverse carbon nanotubes (CNTs) - encompassing various diameters, multi-walled structures (MWNT), single-walled structures (SWNT), and boron-nitrogen nanotubes (BNNT). Analyzing the storage and effective release of hydrogen under different conditions via the radial density function (RDF) revealed that a reduction in radius and the implementation of a double-wall configuration contribute to heightened solid hydrogen storage. While the hydrogen storage capacity of boron-nitrogen nanotubes falls short of that of carbon nanotubes, they notably surpass carbon nanotubes in terms of effective hydrogen storage capacity.

• Journal of KIISE:Databases
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• v.41 no.4
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• pp.242-248
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• 2014

With the rapidly growing amount of information represented in RDF format, efficient querying of RDF graph has become a fundamental challenge. SPARQL is one of the most widely used query languages for retrieving information from RDF dataset. SPARQL is not only simple in its syntax but also powerful in representation of graph pattern queries. However, users need to make a lot of efforts to understand the ontology schema of a dataset in order to compose a relevant SPARQL query. In this paper, we propose a graph query formulation and processing scheme based on ontology schema information which can be obtained by summarizing RDF graph. In the context of the proposed querying scheme, a user can interactively formulate the graph queries on the graphic user interface without making efforts to understand the ontology schema and even without learning SPARQL syntax. The graph query formulated by a user is transformed into a set of class paths, which are stored in a relational database and used as the constraint for search space reduction when the relational database executes the graph search operation. By executing the LUBM query 2, 8, and 9 over LUBM (10,0), it is shown that the proposed querying scheme returns the complete result set.

• Journal of KIISE:Databases
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• v.37 no.4
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• pp.197-202
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• 2010

Recent studies on change detection for RDF data are focused on not only the structural difference but also the semantic-aware difference by computing the closure of RDF models. However, since these techniques which take into account the semantics of RDF model require both RDF models to be memory resident, or they use a forward-chaining strategy which computes the entire closure in advance, it is not efficient to apply them directly to detect changes in large RDF data. In this paper, we propose a scalable change detection technique for RDF data, which uses a backward-chaining inference based on relational database. Proposed method uses a new approach for RDF reasoning that computes only the relevant part of the closure for change detection in a relational database. We show that our method clearly outperforms the previous works through experiment using the real RDF from the bioinformatics domain.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.109-116
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• 2021

Since RDF (Resource Description Framework) triples are modeled as graph, we cannot directly adopt existing solutions in relational databases and XML technology. In order to store, index, and query Linked Data more efficiently, we propose a convergence indexing method combined R*-tree and K-dimensional trees. This method uses a hybrid storage system based on HDD (Hard Disk Drive) and SSD (Solid State Drive) devices, and a separated filter and refinement index structure to filter unnecessary data and further refine the immediate result. We perform performance comparisons based on three standard join retrieval algorithms. The experimental results demonstrate that our method has achieved remarkable performance compared to other existing methods such as Quad and Darq.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.499-507
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• 2007

With the increasing of users' request about internet web service, importance of Internet datawarehouse to support decision making of users is increasing now. Early Internet datawarehouse was studied in the form of using existent database and XML. However, because of limitation of information expression ability, it is gradually changed to system that use metadata schema like RDFS. Because of distributed environment of the Internet, integration and saving of each metadata schemas into one global schema is important. However, between each different schema, semantic and structural conflicts can be happen in such situation and they must be controlled. In this paper, we analyze occasions of conflict when integrate distributed metadata schemas and propose conflict resolution technique for efficient internet datawarehouse query processing.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.45-50
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• 2006

정보의 단순한 연결뿐만 아니라 의미적인 연결 관계를 표현하는 시맨틱 웹에서 RDF와 RDFS만으로는 정보간의 다양한 의미적 관계를 나타내기가 힘들다. 따라서 정보간의 의미적 관계를 보다 명확하게 필요로 하는 분산 환경에서는 시맨틱 웹 언어의 표준으로 인식되고 있는 OWL로 표현된 시맨틱 웹 데이터를 위한 저장 구조가 필요하다. 따라서 본 논문에서는 분산 환경을 고려하여 OWL이 표현하는 다양한 의미적 관계를 이용한 질의 처리를 지원하는 저장 구조를 제안한다. 그리고 OWL에 정의된 클래스 간의 계층 관계를 이용한 질의의 효율적인 처리를 위한 인덱스 구조와 처리 전략을 제안한다.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.563-573
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• 2006

Cyber-infrastructures for scientific and engineering applications require integrating heterogeneous legacy data in different formats and from various domains. Such data integration raises challenging issues: (1) Support for multiple independently-managed schemas, (2) Ease of schema evolution, and (3) Simple schema mappings. In order to address these issues, we propose a novel approach to semantic integration of scientific data which uses XML schemas and RDF-based schema mappings. In this approach, XML schema al-lows scientists to manage data models intuitively and to use commodity XML DBMS tools. A simple RDF-based ontological representation scheme is used for only structural relations among independently-managed XML schemas from different institutes or domains We present the design and implementation of a prototype system developed for the national cyber-environments for civil engi-neering research activities in Korea (similar to the NEES project in USA) which is called KOCEDgrid (http://www.koced.net).

• Proceedings of the Korean Information Science Society Conference
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• 2007.06c
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• pp.293-298
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• 2007

연구자의 R&D 전주기 과정을 지원하기 위해 KISTI에서 2006년 개발된 OntoFrame$^{(R)}$은 과학기술 온톨로지와 DBMS 기반 추론 시스템을 적용하여 추론 서비스를 제공하였다. 2007년 개발중인 OntoFrame$^{(R)}$의 추론 시스템은 대량의 인스턴스를 대상으로 빠른 추론 성능을 제공하기 위해서 저장 구조 변경 및 추론 프로세스 변경을 통해 추론 시스템의 성능을 개선하는데 중점을 두고 있다. 본 연구에서는 추론 시스템의 개선을 위해서 RDF 트리플의 데이터 구조 및 테이블 구조 변경, EMPV(Expanded Multiple Properties View) 개발 및 도입, 추론 서비스와 추론 시스템의 프로세스 변경, 저장 구조 관리기의 개발 연구를 수행하였다. 데이터 구조 및 테이블 구조 변경을 통해서 저장 공간의 오버헤드를 개선하였고, EMPV의 도입을 통해서 트리플 저장 구조의 비효율적인 자료 접근 방식을 개선하였으며, 프로세스 개선을 통해 추론에 소용되는 시간을 단축하였다. 또한 관리기 도입을 통해서 사용자 편의성 및 추론 시스템의 관리 기능을 제공하였다.