• Journal of Computing Science and Engineering
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• v.1 no.1
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• pp.95-123
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• 2007

Existing systems that support semistructured views do not maintain semantics during the process of designing the views. Thus, these systems do not guarantee the validity and reversibility of the views. In this paper, we propose an approach to address the issue of valid and reversible semistructured views, We design a set of view operators for designing semistructured views. These operators are select, drop, join and swap. For each operator, we develop a complete set of rules to maintain the semantics of the views. In particular, we maintain the evolution and integrity of relationships once an operator is applied. We also examine the reversible view problem under our operators and develop rules to guarantee that the designed views are reversible. Finally, we examine the changes in the participation constraints of relationship types during the view design process, and develop rules to ensure the correctness of the participation constraints.

• Journal of KIISE:Software and Applications
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• v.32 no.6
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• pp.554-569
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• 2005

In the semistructured distributed documents, it is very difficult to formalize and implement the query processing system due to the lack of structure and rule of the data. In order to precisely retrieve and process the heterogeneous semistructured documents, it is required to handle multiple mappings such as 1:1, 1:W and W:1 on an element simultaneously and to generate the schema from the distributed documents. In this paper, we have proposed an query processing algorithm for querying and answering on the heterogeneous semistructured data or documents over distributed systems and implemented with a metadata interface. The algorithm for generating local queries from the global query consists of mapping between g1oba1 and local nodes, data transformation according to the mapping types, path substitution, and resolving the heterogeneity among nodes on a global input query with metadata information. The mapping, transformation, and path substitution algorithms between the global schema and the local schemas have been implemented the metadata interface called DBXMI (for Distributed Documents XML Metadata Interface). The nodes with the same node name and different mapping or meanings is resolved by automatically extracting node identification information from the local schema automatically. The system uses Quilt as its XML query language. An experiment testing is reported over 3 different OEM model semistructured restaurant documents. The prototype system is developed under Windows system with Java and JavaCC compiler.

• 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.

• The KIPS Transactions:PartD
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• v.11D no.2
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• pp.305-316
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• 2004

XML is becoming the de facto standard for data exchange over the Internet as a semistructured data which properties are irregular and incomplete. Therefore, to handle these data efficiently. what we use storage devices and storage techniques are Primary factors. In this paper, we developed storage techniques, which take the virtues of an object-relational database and support various query types needed for XML query languages without regard to the DTD. The techniques are capable with connecting naturally with conventional data and reducing overheads caused by the characteristics of an XML data model.

• Journal of KIISE:Databases
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• v.28 no.4
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• pp.723-731
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• 2001

As XML has become and emerging standard for information exchange on the World Wide Web it has gained attention in database communities of extract information from XML seen as a database model. Data in XML can be mapped to semistructured dta model based on edge-labeled graph and queries can be processed against it Here we propose new query optimization techniques using DTDs(Document Type Definitions) which have the schema information about XML data. Our techniques reduce traditional index techniques Also, as they preserve source database structure, they can process many kinds of complex queries. we implemented our techniques and provided preliminary performance results.

• Journal of KIISE:Databases
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• v.29 no.3
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• pp.217-229
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• 2002

Regular path expressions are primary elements for formulating queries over the semistructured data that does not assume the conventional schemas. In addition, the query pruning is an important optimization technique to avoid useless traversals in evaluating regular path expressions. However, the existing query pruning often fails to fully optimize multiple regular path expressions, and the previous methods that post-process the result of the existing query pruning must check exponential combinations of sub-results. In this paper, we present a new query pruning technique that consists of the preprocessing phase and the pruning phase. Our two-phase query pruning is affective in optimizing multiple regular path expressions, and is more scalable than the previous methods in that it never check the exponential combinations of sub-results.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.495-506
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• 2001

XML makes it possible for data to be exchanged regradless of the data model in which it is represented or the platform on which it is stored, serving as a standard for data exchange format on the internet. Especially, it is natural to send XML data without DTD on the internet when XML is data-centric. Therefore it is needed to extract relational schema to store XML data efficiently, to optimize queries, and to publish data which have been stored in the relational database in the XML format. In this paper, we proposed a method to generate relational database in the XML documents without DTD and store XML data using upper/lower bound schema extraction technique for semistructured data. In extracting a lower bound schema, we especially show an efficient technique for creating relational schema by using simulation with is more advanced than the datalog method.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.193-195
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• 2004

데이터베이스에 저장된 수많은 자료들을 사용자의 질의에 맞추어 웹상에서 표현해주는 것이 바로 리포팅 툴의 역할이다. 그에 관한 연구들로 BBQ(Blended Browsing and Querying), EASY BASE, QURSED(Querying and Reporting Semistructured Data)와 같은 여러 리포팅 툴들이 상용화되어 있다. 하지만 사용자가 보다 쉽고 직관적으로 XML 문서를 작성하고 관리할 수 있는 툴들은 미흡한 것이 사실이다. 이 논문에서는 XML과 XSL문서를 각각 그룹핑하고 직관적인 구조로 표현 해주며 사용자의 관점에 맞추어 XQuery를 지원하는 시스템을 설계 구현하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.1915-1918
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• 2002

Managing semistructured data needs fine granularity such as markup elements. XML has major effect in managing web content, it enables content reusability, enriches information with metadata, ensures valid document links, etc. We introduce our content model as an integrated work which handles content objects as controllable units. The paper concerns on modeling news site and how the content is classified due to the site structure, aggregated content and reusability. The model stores instance XML document into relation database using fragmentation strategy.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.302-304
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• 2000

인터넷의 발달로 웹에는 엄청난 데이터가 존재하나, 불규칙적인 구조를 이루고 있는 반구조적 데이터가 대부분이다. 이러한 반구조적 데이터는 데이터들간의 어떤 정확하게 정해진 구조를 갖고 있진 않지만 불완전하고 불규칙한 구조 정보를 포함하고 있는 것으로, 데이터들 간의 관계를 규명할 수 있는 공통 구조 정보를 추출하여 효과적으로 구조화시킴으로써 정보로서의 가치를 높일 필요성이 대두되게 되었다. 또, 데이터 처리 과정에서 기존의 잘 정의된 구조를 가진 데이터베이스의 장점을 수용하기 위해서는 반구조적 데이터 집합의 불완전한 구조 정보로부터 공통 구조를 추출하는 것이 요구된다. 본 연구에서는 후보 항목 집합의 생성이 없는 빈발 패턴 탐사 기법을 사용하여 반구조적 데이터 집합으로부터 공통구조를 추출하고자 한다.