• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.10-12
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• 2004

Nowadays, with the rapid emergence of XML as a standard for data exchange over the Internet had led to considerable interest In the problem of data management requirements such as the need to store and query XML documents in which the location path languages Xpath is of particular important for XML application since it is a core component of many XML processing standards such as XSLT or XQuery, This parer gives a brief overview about method and design by applying a new spatial-based indexing method namely Xp-free that used for supporting Xpath. Spatial indexing technique has been proved its capacity on searching in large databases. Based on accelerating a node using planar as combined with the numbering schema, we devise efficiently derivative algorithms, which are simple, but useful. Besides that, it also allows to trace all Its relative nodes of context node In a manner supporting queries natural to the types especially Xpath queries with predicates.

• Journal of KIISE:Databases
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• v.35 no.3
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• pp.243-256
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• 2008

With rapid growth of Internet, the amount of information in the Web is increasing exponentially. However, information on the current Web is understandable only for human, and thus it makes the exact information retrieval difficult. For solving this problem, the Semantic Web is suggested and we must use ontology languages that can endow data to semantics for implementing it. One of the representative ontology languages is OWL(Web Ontology Language) adopted as a recommendation by the World-Wide Web Consortium. OWL has richer expression power and formal semantics than other ontology languages such as RDF and RDF-S. In addition, OWL includes hierarchical structure information between classes or properties. Therefore, an efficient OWL storage model considering hierarchical structure for effective information retrieval on the Semantic Web is required. In this paper, we suggest the XPOS(XPath-based OWL Storage) model including hierarchy information between classes or properties as XPath form and enabling intuitive and effective information retrieval. Also, we show the comparative evaluation results on the performance of XPOS model, Sesame, and the XML storage-based storage model regarding query processing.

• Journal of KIISE:Databases
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• v.34 no.1
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• pp.1-17
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• 2007

As XML is becoming a de facto standard for distribution and sharing of information, the need for an efficient yet secure access of XML data has become very important. To enforce the fine-level granularity requirement, authorization models for regulating access to XML documents use XPath which is a standard for specifying parts of XML data and a suitable language for both query processing. An access control environment for XML documents and some techniques to deal with authorization priorities and conflict resolution issues are proposed. Despite this, relatively little work has been done to enforce access controls particularly for XML databases in the case of query access. Developing an efficient mechanism for XML databases to control query-based access is therefore the central theme of this paper. This work is a proposal for an efficient yet secure XML access control system. The basic idea utilized is that a user query interaction with only necessary access control rules is modified to an alternative form which is guaranteed to have no access violations using tree-aware metadata of XML schemes and set operators supported by XPath 2.0. The scheme can be applied to any XML database management system and has several advantages over other suggested schemes. These include implementation easiness, small execution time overhead, fine-grained controls, and safe and correct query modification. The experimental results clearly demonstrate the efficiency of the approach.

• The KIPS Transactions:PartD
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• v.12D no.2 s.98
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• pp.189-198
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• 2005

XML is rapidly becoming the standard for data representation and exchange, and XML documents are being adopted in various applications. Since the late 1990s, some native XML database management systems(DBMSs) have been developed. More recently, commercial relational DBMS vendors try to incorporate full functionalities of XML into their products, such as Oracle, MS SQL and IBM DB2. In this paper, we implement a well-known RDBMS-based XML data storage and indexing technique, called XPath Accelerator, and tune it in an industry-leading RDBMS. Our contributions are two-folds: 1) an in-depth implementation of the XPath Accelerator technique and 2) its tuning to exploit the advanced query processing techniques of an RDBMS.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.540-552
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• 2004

We propose XIR-Linear, a novel method for processing partial match queries on large-scale heterogeneous XML documents using information retrieval (IR) techniques. XPath queries are written in path expressions on a tree structure representing an XML document. An XPath query in its major form is a partial match query. The objective of XIR-Linear is to efficiently support this type of queries for large-scale documents of heterogeneous schemas. XIR-Linear has its basis on the schema-level methods using relational tables and drastically improves their efficiency and scalability using an inverted index technique. The method indexes the labels in label paths as key words in texts, and allows for finding the label paths that match the queries far more efficiently than string match used in conventional methods. We demonstrate the efficiency and scalability of XIR-Linear by comparing it with XRel and XParent using XML documents crawled from the Internet. The results show that XIR-Linear is more efficient than both XRel and XParent by several orders of magnitude for linear path expressions as the number of XML documents increases.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.585-596
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• 2007

XML data generally consists of a hierarchical tree-structure which is reflected in mechanisms to store and retrieve XML data. Therefore, when storing XML data in the database, the hierarchical relationships among the XML elements are taken into consideration during the restructuring and storing of the XML data. Also, in order to support the search queries from the user, a mechanism is needed to compute the hierarchical relationship between the element structures specified by the query. The structural join operation is one solution to this problem, and is an efficient computation method for hierarchical relationships in an in database based on the node numbering scheme. However, in order to process a tree structured XML query which contains a complex nested hierarchical relationship it still needs to carry out multiple structural joins and results in another problem of having a high query execution cost. Therefore, in this paper we provide a preprocessing mechanism for effectively reducing the cost of multiple nested structural joins by applying the concept of equivalence classes and suggest a query path reduction algorithm to shorten the path query which consists of a regular expression. The mechanism is especially devised to reduce path queries containing branch nodes. The experimental results show that the proposed algorithm can reduce the time requited for processing the path queries to 1/3 of the original execution time.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1133-1148
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• 2012

This paper presents a hierarchical structuring method for the multidimensional type inheritance indices (MD-TIXs) that support the processing of XML queries in XML databases. MD-TIX uses a multidimensional index structure for efficiently supporting ancestor-descendant explorations that involve both nested element and type inheritance hierarchies. However, In the case of a long Xpath, the building and maintenance of MD-TIX are very difficult because of index entry construction problem. So, we propose a type inheritance index hierarchy method for solving this difficulty. We first construct base indices that support direct relationship explorations between adjacent two types on a given Xpath, and then, based on these base indices, we construct hierarchically the derived indices that support indirect relationship explorations between any two types of Xpath until constructing one target index for supporting the full Xpath. And we also present an algorithm that efficiently constructs a partial index hierarchy for supporting given a set of sub-pathes explorations.

• Journal of KIISE:Databases
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• v.35 no.4
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• pp.307-318
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• 2008

One of the primary issues confronting XML message brokers is the difficulty associated with processing a large set of continuous XPath queries over incoming XML seams. This paper proposes a novel system designed to present an effective solution to this problem. The proposed system transforms multiple XPath queries before their run-time into a new region-based data structure, called an XP-table, by sharing their common constraints. An XP-table is matched with a stream relation (SR) transformed from a target XML stream by a SAX parser. This arrangement is intended to minimize the runtime workload of continuous query processing. Also, system performance is estimated and verified through a variety of experiments, including comparisons with previous approaches such as YFilter and LazyDFA. The proposed system is practically linear- scalable and stable for evaluating a set of XPath queries in a continuous and timely fashion.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.5
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• pp.492-506
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• 2009

Index structures that are based on sequence matching for XPath processing such as ViST, PRIX and LCS-TRIM have recently been proposed to reduce the search time of XML documents. However, ViST can cause a lot of unnecessary computation and I/O when processing structural joint queries because its numbering scheme is not optimized. PRIX and LCS-TRIM require much processing time for matching XML data trees and queries. In this paper, we propose a novel index structure that solves the problems of ViST and improves the performance of PRIX and LCS-TRIM. Our index structure provides the minimum sequence matching scheme to efficiently process structural queries. Finally, to verify the superiority of the proposed index structure with the minimum sequence matching scheme, we compare our index structure with ViST, PRIX and LCS-TRIM in terms of query processing of a single path or of a branching path including wild-cards ('*' and '//' ).

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.277-279
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• 2002

효율적인 문서 교환을 위해 의미 있는 태그를 사용하는 XML문서가 인터넷상에서 널리 사용되고 있다. XML문서에 대한 정보를 추출하기 위해 많은 질의어가 사용되고있지만 특히 정규 경로 표현에 있어 임의 이동이 쉽고 질의 표현이 쉬운 XPath[2]가 사람들에게 각광을 받고 있다. 이 연구에서는 XPath[2]를 이용하여 사용자 질의를 등록하고, 등록된 질의를 이용하여 효율적으로 XML문서를 필터링하기 위한 방법을 제안한다. 본 논문에서는 NiagaraCQ[1]와 같이 XML문서 정보를 이용하여 사용자에게 계속적으로 XML문서를 제공하는 Continuous Query 시스템에 사용된 SFilter를 설계하고 구현하였다.