• 한국공간정보시스템학회:학술대회논문집
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• 2000.06a
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• pp.37-48
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• 2000

지리정보시스템(GIS)의 사용이 확대되고 있는 현재 상황에서 다양한 분야에서 구축되어 서로 다른 환경에 분산되어 있는 이질적인 지리 데이타의 공유에 대한 중요성은 더욱 증가하고 있는데, 이러한 상호운용성을 지원하기 위하여 개발된 것이 OGC의 OpenGIS이다. OGC는 다양한 분야에서 차세대 표준으로 주목받고 있는 XML을 GIS에 도입하려는 움직임으로 GML 사양을 제시하고 있다. 향후 사용이 더욱 증가하게 될 XML 문서 형태의 지리 데이타에 대한 GIS 사용자들의 접근을 허용하기 위해서 OpenGIS를 지원하는 XML 데이타 제공자의 설계 및 구현이 절실히 필요하다. 본 논문에서는 OGC의 세 가지 구현 사양 중 특히 Microsoft의 OLE/COM을 기반으로 하는 OpenGIS Simple Features Specification for OLE/COM 사양과 지리 데이타의 XML 인코딩을 위한 GML 사양을 기반으로 XML 데이타 제공자를 설계 및 구현하였다. 본 논문에서 개발한 XML 데이타 제공자는 표준화된 지리 데이타 구조와 처리에 대한 인터페이스를 지원하여 상호운용성을 보장하고, XML 기술을 활용하여 XML데이타의 효율적인 분석 기능도 제공한다. 따라서 XML 데이타 제공자를 사용함으로써 표준화된 DTD를 따르는 XML 문서내의 지리 데이터를 OpenGIS를 지원하는 이질의 데이타 소스의 지리 데이타와 함께 공유할 수 있고, XML 문서의 구조를 효율적으로 검증할 수 있으며, 또한 XML 데이타에 대한 접근 및 분석이 가능하게 된다.

• Journal of KIISE:Databases
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• v.34 no.3
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• pp.270-281
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• 2007

Recently, there has been growing interest in streaming XML data. Much of the work on streaming XML data has been focused on efficient filtering of XML data. Such XML filtering systems deliver XML documents to interested users. The burden of extracting the XML fragments of interest from XML documents is placed on users. As a result, several evaluation techniques for streaming XML data, which only extract interested XML fragments by directly evaluating XML queries on streaming XML data, have been proposed. However, existing evaluation techniques for streaming XML data only support the restricted subset of XPath queries, and multiple queries cannot be evaluated by such evaluation techniques. In this paper, we propose XTREAM which evaluates multiple queries in conjunction with the read-once nature of streaming data. In contrast to the previous work, XTREAM supports a wide class of XPath queries including order based predicates and so on. Experimental results with real-life and synthetic XML data demonstrate the efficiency and scalability of XTREAM.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.109-111
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• 2003

관계형 데이타베이스에 저장되어 있는 데이타를 XML 문서로 추출하기 위해서는 데이블에 저장된 데이타를 XML 문서 형식에 맞는 계층적인 관계를 가지도록 구조화하는 과정이 필요하다. 본 논문에서는 관계형 데이타베이스를 사용하는 XML 저장 및 검색 시스템인 eXDM(embedded XML Database Management System)의 내부에서 구현한 XML 문서 추출 서브시스템에 대하여 기술한다. 이 시스템은 XML 문서에 대한 질의(XQuery)의 RETURN 절과 SORTBY 절을 분석하여, 관계형 데이타베이스에 저장되어 있는 데이타를 구조화하여 계층적인 구조를 가지는 XML 문서 형태로 추출한다.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.243-253
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• 2005

Dissemination of XML data on the internet could breach the privacy of data providers unless access to the disseminated XML data is carefully controlled. Recently, the methods using encryption have been proposed for such access control. However, in these methods, the performance of processing queries has not been addressed. A query processor cannot identify the contents of encrypted XML data unless the data are decrypted. This limitation incurs overhead of decrypting the parts of the XML data that would not contribute to the query result. In this paper, we propose the notion of query-aware decryption for efficient processing of queries against encrypted XML data. Query-aware decryption allows us to decrypt only those parts that would contribute to the query result. For this purpose, we disseminate an encrypted XML index along with the encrypted XML data. This index, when decrypted, informs us where the query results are located in the encrypted XML data, thus preventing unnecessary decryption for other parts of the data. Since the size of this index is much smaller than that of the encrypted XML data, the cost of decrypting this index is negligible compared with that for unnecessary decryption of the data itself. The experimental results show that our method improves the performance of query processing by up to 6 times compared with those of existing methods. Finally, we formally prove that dissemination of the encrypted XML index does not compromise security.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.31-33
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• 2003

문서를 표현하는 여러 가지 기법 중에서 XML(eXtensible Markup Language)은 확장성과 범용성 때문에 데이타의 교환과 표현에 대한 표준으로 자리잡고 있다. 이에 XML로 데이타를 저장하기 위한 다양한 방법들이 제시되고 있다. 본 논문에서는 관계형 데이타베이스에 XML 데이타를 저장하기 위해 XML 데이터의 타입을 관계형 데이타베이스의 타입으로 매칭해 주는 서브시스템인 타입 처리기를 구현한다. 타입 처리기에서는 eXDM이 내장형 시스템이라는 제한사항을 고려하고, XQuery 형태의 질의문을 지원하기 위해 XML-스키마를 변형한 형태의 XML 타입 정의 문서를 이용한다.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.432-443
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• 2004

As the XML data has been widely used in the Internet, it is necessary to store and retrieve the XML data by using DBMSs. However, relational DBMSs suffer from the model difference between graph structure of the XML data and table forms in relational databases. We propose an ORDBMS-based DTD-dependent XML data management system Xing. Xing stores XML data in a DTD-dependent form in an object database. Since the object database schema has a graph structure and supports multi-valued attributes, mapping from an XML data model and queries into an object data model and OQLs is a simple problem. For rapid storing of large quantities of the XML data, we use SAX parser with customized Xing-tree which requires a small memory space compared with the DOM-tree. Xing also returns the query result in an XML document form. We have implemented the Xing system on top of UniSQL object-relational DBMS for the validity checking and performance comparison. For XML genome data from GenBank, and experimental evaluation shows that Xing can provide significant performance improvement (maximum 10 times) compared with the relational approach.

• 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.33 no.2
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• pp.224-238
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• 2006

As XML became the standard of data exchange in the internet, the needs for effective query processing for XML data in streaming environment is increasing. Applying the existing database technique which processes data with the unit of tuple to the streaming XML data causes the out-of-memory problem due to limited memory volume. Likewise the cost for searching query path and accessing specific data may be remarkably increased because of special structure of XML. In a word it is unreasonable to apply the existing database system to the streaming environment that processes query for partial data, not the whole one. Thus, it should be able to search partial streaming data that rapidly satisfies join predicate through using low-capacity memory, based on a store technique suitable to streaming XML data. In this thesis, in order to study the store technique for low-capacity memory, the PCDATA and the CDATA-related parts, which can be used as predicate on join query, were fetched and saved. In addition, in an attempt to compare rapid join predicates, the range window of streaming XML data was set with the object of selectively joining windows that satisfies the query, based on Cardinality * and + among the structure information of DTD.

• Journal of KIISE:Databases
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• v.33 no.7
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• pp.668-681
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• 2006

Due to its diverse advantages, XML has secured its position as a standard for data representation and exchange in the Internet. As a consequence, there has been much research on efficient storing and query processing of in data. Storing XML data in a relational database system warrants much benefit in data management and query processing; the system provides a strong query processing and data management function and can be applicable to XML data, its function being extended. In this paper, we design and implement a query translator that translates XQuery, a representative XML query language, into SQL:2003 query. SQL:2003, the latest SQL standard used as a substitute for SQL:1999, defines SQL/XML that supports XML. The main contribution of this paper is as follows: First, we look into the supporting features of XML, defined in the SQL:2003 standard, and propose a user-defined function for shortcoming sections. Second, we propose a way to translate XQuery into SQL that observes the latest SQL standard. Third, we describe in detail the design and the implementation of the translator to show its feasibility as a translator.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.1
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• pp.1-8
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• 2002

XML has been proposed as an international standard for organizing and exchanging a great diversity of the Web data. It is important to retrieve components of stored XML documents that are needed by a wide variety of applications. In this paper, we suggest a method to store XML documents and to retrieve an XML data. In other words, we suggest the method of retrieving XML data is using XML -QL. So we need to mapping XML-QL to SQL translator on top of an RDBMS. The contributions of this paper include, besides the detailed design and implementation of the translator, demonstration of feasibility of such a translator, and a comprehensive classification of XML queries and their mappings to SQL relational queries.