• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.82-84
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• 2005

시맨틱 웹의 등장에 따라 RDF와 RDF Schema(RDF/RDFS)로 표현되는 웹 데이타의 양이 증가하고 있다. 이에 웹 데이타를 효율적으로 저장, 검색할 수 있는 인덱스 구조의 필요성이 높아지고 있다. 본 연구에서는 기존의 트리 모델을 위한 소수 레이블 기법(prime number labeling scheme)을 발전시켜, RDF/RDFS 인덱스 구조를 표현할 수 있는 그래프 모델을 위한 소수 레이블 기법을 제안한다. 제안한 기법은 기존의 소수 레이블 기법을 그래프에 적용하여 구조 질의(Structural Query)를 효율적으로 처리할 수 있고, 데이타 갱신 시에 인덱스를 재구성하지 않아도 되는 장점을 가지고 있다. 그리고 이전의 RDF/RDFS 인덱스 구조에서 효율적으로 처리하기 힘들었던 순환 방향성 그래프에 대한 질의도 쉴게 처리할 수 있다.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.151-162
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• 2006

RDF Semantics, one of W3C Recommendations, provides the RDFS entailment rules, which are used for the RDFS inference. Sesame, which is well known RDF repository, supports the RDBMS-based RDFS inference using the forward-chaining strategy. Since inferencing in the forward-chaining strategy is performed in the data loading time, the data loading time in Sesame is slow down be inferencing. In this paper, we propose the order scheme for applying the RDFS entailment rules to improve inference performance. The proposed application order makes the inference process terminate without repetition of the process for most cases and guarantees the completeness of inference result. Also the application order helps to reduce redundant results during the inference by predicting the results which were made already by previously applied rules. In this paper, we show that our approaches can improve the inference performance with comparisons to the original Sesame using several real-life RDF datasets.

• Journal of the Korea Society of Computer and Information
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• v.14 no.1
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• pp.35-45
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• 2009

According to the widespread use of ontology documents, a management system which store ontology data and process queries is needed for retrieving semantic information efficiently. In this paper I propose a storage schema that stores and retrieves semantic web documents based on RDF/RDFS ontology language developed by W3C in a relational databases. Specially, the proposed storage schema is designed to retrieve efficiently hierarchy information and to increase efficiency of query processing. Also, I describe a mechanism to transform RQL semantic queries to SQL relational queries and build up database using MS-ACCESS and implement in this paper. According to the result of implementation, we can blow that not only data query based on triple model but also query for schema and hierarchy information are transformed simply to SQL.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.1
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• pp.19-30
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• 2014

For the expansion of the Semantic Web, studies in converting the data stored in the relational database into the ontology are actively in process. Such studies mainly use an RDB to RDF mapping model, the model to map relational database components to RDF components. However, pre-proposed mapping models have got different expression modes and these damage the accessibility and reusability of the users. As a consequence, the necessity of the standardized mapping language was raised and the W3C suggested the R2RML as the standard mapping language for the RDB to RDF model. The R2RML has a characteristic that converts only the relational database schema data to RDF. For the same reasons above, the ontology about the relation data between table name and column name of the relational database cannot be added. In this paper, we propose an RDB to RDF mapping system considering semantic relations of RDB components in order to solve the above issue. The proposed system generates the mapping data by adding the RDFS attribute data into the schema data defined by the R2RML in the relational database. This mapping data converts the data stored in the relational database into RDF which includes the RDFS attribute data. In this paper, we implement the proposed system as a Java-based prototype, perform the experiment which converts the data stored in the relational database into RDF for the comparison evaluation purpose and compare the results against D2RQ, RDBToOnto and Morph. The proposed system expresses semantic relations which has richer converted ontology than any other studies and shows the best performance in data conversion time.

• 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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• 2006.06a
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• pp.244-246
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• 2006

최근 들어서 생물학, 건설, 토목, 의학, 화학, 항공 등 다양한 과학 분야에서 효율적인 공동 연구를 돕기 위해서 그리드 기반 데이터 통합을 위한 많은 연구가 진행되고 있다. 하지만 각 분야에서 사용하는 이질적인 형식의 데이터를 원활히 통합하는 것은 매우 어려운 문제이다. 이러한 측면에서, XML은 이질적인 시스템 간 데이터 공유의 수단으로서 광범위하게 사용되고 있으나, 데이터를 의미적으로 통합하는데 에는 한계가 있다. 이 문제를 해결하기 위해서, 본 논문에서는 그리드 환경에서 XML Schema 에 기반을 둔 이질적인 데이터 소스들을 의미적으로 통합하고 검색하는 방법으로서 RDF/RDFS 기반의 온톨리지 매핑을 통한 통합 검색 방안을 제안한다. 우리가 제안하는 방법은 특히 데이터를 XML Schema를 이용해서 표현하기 때문에 원래 데이터소스에 대한 수정 없이도, XML Schema 기반의 구조적 검색뿐 아니라, 온톨로지 기반의 의미적인 데이터 통합 및 검색을 가능하게 한다. 우리는 이 방법을 토목 분야의 시스템에 적용하여 검증하였다.

• Journal of the Korea Society of Computer and Information
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• v.14 no.1
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• pp.173-181
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• 2009

This paper proposes an algorithm to transform RDF(Resource Description Framework) models for ontology into CPN(Colored Petri Net) models. The algorithm transforms the semantics of the RDF model into the topology of the CPN by mapping the classes and the properties of the RDF onto the places of the CPN model then reflects the RDF statements on the CPN by representing the relationships between them as token transitions on the CPN. The basic idea of reflecting the RDF statements on the CPN is to generate a token, which is an ordered pair consisting of two tokens (one from the place mapped into the subject and the other one from the place mapped into the object) and transfer it to the place mapped into the predicate. We have actually built CPN models for given RDF models on the CNPTools and inferred and extracted answers to the RDF queries on the CPNTools.

• Journal of KIISE
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• v.41 no.10
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• pp.762-773
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• 2014

As the web of data is increasingly producing large RDFS datasets, it becomes essential in building scalable reasoning engines over large triples. There have been many researches used expensive distributed framework, such as Hadoop, to reason over large RDFS triples. However, in many cases we are required to handle millions of triples. In such cases, it is not necessary to deploy expensive distributed systems because logic program based reasoners in a single machine can produce similar reasoning performances with that of distributed reasoner using Hadoop. In this paper, we propose a scalable RDFS reasoner using logical programming methods in a single machine and compare our empirical results with that of distributed systems. We show that our logic programming based reasoner using a single machine performs as similar as expensive distributed reasoner does up to 200 million RDFS triples. In addition, we designed a meta data structure by decomposing the ontology triples into separate sectors. Instead of loading all the triples into a single model, we selected an appropriate subset of the triples for each ontology reasoning rule. Unification makes it easy to handle conjunctive queries for RDFS schema reasoning, therefore, we have designed and implemented RDFS axioms using logic programming unifications and efficient conjunctive query handling mechanisms. The throughputs of our approach reached to 166K Triples/sec over LUBM1500 with 200 million triples. It is comparable to that of WebPIE, distributed reasoner using Hadoop and Map Reduce, which performs 185K Triples/sec. We show that it is unnecessary to use the distributed system up to 200 million triples and the performance of logic programming based reasoner in a single machine becomes comparable with that of expensive distributed reasoner which employs Hadoop framework.

• Journal of Information Technology Services
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• v.4 no.2
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• pp.79-97
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• 2005

With the proliferation of EC, many customers have been participating into online auction or group-buying market over searching internet shopping-malls to purchase goods. To support the customer's convenient transaction, lots of agent systems are developed to facilitate the customer's product brokering, merchant brokering, and negotiation of transaction. However, many of these systems have focused upon supporting transaction at only one type of marketplace. Since these marketplaces have different transaction settlement mechanism, it is necessary to develop the system that utilizes the customer's transaction including the selection of the type of marketplace to buy. Then we classify the kinds of B2C electronic marketplace according to the protocol by which the market operated. The structure of negotiation message is developed using XML schema and RDFS under the characteristics and message example of each marketplace in this research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1585-1600
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• 2009

The goal of Semantic Web is to provide efficient and effective semantic search and web services based on the machine-processable semantic information of web resources. Therefore, the process of creating and adding computer-understandable metadata for a variety of web contents, namely, semantic annotation is one of the fundamental technologies for the semantic web. Recently, in order to manage annotation metadata, direct approach for embedding metadata into the document is mainly used in semantic annotation. However, many semantic annotation tools for web documents have been mainly worked with HTML documents, and most of these tools do not support semantic search functionalities using the metadata. In this paper, based on these problems and previous works, we propose the Ontology-based Semantic Annotation tool(OSA) to efficiently support semantic annotation for web documents(such as HTML, PDF). We define a semantic annotation model that represents ontological-semantic information by using RDFS(RDF Schema). Based on XMP(eXtensible Metadata Platform) standard, the model is encoded directly into the document. By using OSA with XMP, user can perform semantic annotation on web documents which are able to keep compatibility for managing annotation metadata. Eventually, the integrated semantic annotation metadata can be used effectively in semantic search for a variety of web contents.