• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.51-54
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• 2005

This paper proposes an index structure which is used to process X-Path on S-XML data. There are many previous index structures based on tree structure for X-Path processing. Because of general tree index's top-down query fashion, the unnecessary node traversal makes heavy access and decreases the query processing performance. And both of the two query types for X-Path called single-path query and branching query need to be supported in proposed index structure. This method uses a combination of path summary and the node indexing. First, it manages hashing on hierarchy elements which are presented in tag in S-XML. Second, array blocks named path summary array is created in each node of hashing to store the path information. The X-Path processing finds the tag element using hashing and checks array blocks in each node to determine the path of query's result. Based on this structure, it supports both single-path query and branching path query and improves the X-Path processing performance.

• Journal of KIISE:Databases
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• v.31 no.1
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• pp.61-71
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• 2004

XML can describe a wide range of data, from regular to irregular and from flat to deeply nested. Thus, XML is rapidly emerging as the do facto standard for the Web document format since XML supports an efficient data exchange and integration. Also, to retrieve the data represented by XML, several XML query languages are proposed. XML query languages such as XPath and XQuery use path expressions to traverse irregularly structured data which comprise B% elements. To evaluate path expressions, various path indexes are proposed. However, traditional path indexes are constructed by utilizing only the XML data structure. Therefore, in this paper, we propose an adaptive path index which utilizes the XML data structure as well as query workloads. To improve the query performance, the adaptive path index proposed by this paper manages the frequently used paths and the structural summary of the XML data using a hash tree and a graph structure. Experimental results show that the adaptive path index improves the query performance typically 2 to 69 times compared with the existing indexes.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.785-786
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• 2017

본 연구는 regular path query를 효율적으로 처리하는 디스크 기반 시스템을 만들기 위해서는 그래프 데이터를 효율적으로 저장하여야하며, regular path query 수행 시 발생하는 cost가 작도로 하는 evaluation algorithm이 필요하다. 이에 본 연구에서는 그래프데이터 저장 방법을 제안하고, regular path query 수행시 발생하는 cost 및 오버헤드를 분석한다.

• Journal of KIISE:Databases
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• v.32 no.2
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• pp.204-218
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• 2005

XML has rapidly emerged as the standard for the interchange of data in numerous application areas. To support for efficient queries against XML data, many query languages have been designed. The query languages require the users to know the structure of the XML documents and specify search conditions on the structure. This path-based query against XML documents is a natural consequence of the hierarchical structure of XML. However, it is also desirable to allow the users to formulate no path queries against XML documents, to complement the current path-based queries. In this paper, we design a query expression capable of querying without knowledge about the structure of XML documents, and develop a query processor to evaluate no path queries.

• Journal of KIISE:Databases
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• v.29 no.4
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• pp.274-284
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• 2002

Queries on XML are based on paths in the data graph, which is represented as an edge labeled graph model. All proposed query languages for XML express queries using regular expressions to traverse arbitrary paths in the data graph. A meaningful query usually has several regular path expressions in it, but much of recent research is more concerned with optimizing a single path expression. In this paper, we present an efficient technique to process multiple path expressions in a query. We developed a data structure named as the path identifier(PID) to identify whether two given nodes lie on the fame path in the data graph or not, and utilized the PID for efficient processing of multiple path expressions. We implement our technique and present preliminary performance results.

• Journal of the Korea Society of Computer and Information
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• v.17 no.10
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• pp.107-116
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• 2012

The applying of semantic technologies that aim to let computers understand and automatically process the meaning of the interlinked data on the Web is spreading. In Semantic Web, understanding and accessing the associations between data that is, the meaning between data as well as accessing to the data itself is important. W3C recommended RDF (Resource Description Framework) as a standard format to represent both Semantic Web data and their associations and also proposed several RDF query languages in order to support query processing for RDF data. However further researches on the query language definition considering the semantic associations and query processing techniques are still required. In this paper, using the suffix array-based indexing scheme previously introduced for RDF query processing, we propose a query processing approach to handle ${\rho}$-path query which is the representative type of semantic associations. To evaluate the query processing performance of the proposed approach, we implemented two different types of query processing approaches and measured the average query processing times. The experiments show that the proposed approach achieved 1.8 to 2.5 and 3.8 to 11 times better performance respectively than others two.

• 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.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.558-566
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• 2005

The XML is the new standard fir data representation and exchange on the Internet. In this paper, we describe a new approach for evaluating a path-oriented query against XML document. In our approach, we propose the Parallel Match Indexing Fabric to speed up evaluation of path-oriented query using path signature and design the parallel match algorithm to perform a match process between a path signature of input query and path signatures of elements stored in the database. To construct a structure of the parallel match indexing, we first make the binary tie for all path signatures on an XML document and then which trie is transformed to the Parallel Match Indexing Fabric. Also we use the Parallel Match Indexing Fabric and a parallel match algorithm for executing a search operation of a path-oriented query. In our proposed approach, Time complexity of the algorithm is proportional to the logarithm of the number of path signatures in the XML document.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1311-1317
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• 2007

Recently, due to the popularity and explosive growth of the Internet, the information exchange is increasing so rapidly over the Internet. Also the XML is becoming a standard as well as a major tool of data exchange on the Internet and thus we propose the new indexing technique for evaluating a path-oriented query and design and implementation of Path-oriented Query Processing System to give useful for users. In proposed indexing technique, which combined a binary trio structure with a path signature file to improve performance of XML document retrieval.

• Journal of KIISE:Databases
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• v.30 no.2
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• pp.109-124
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• 2003

Although most commercial relational DBMSs Provide a graphical query language for the user friendly interfaces of the databases, few research has been done for graphical query languages in object databases. Expressing complex query conditions in a concise and intuitive way has been an important issue in the design of graphical query languages. Since the object data model and object query languages are more complex than those of the relational ones, the graphical object query language should have a concise and intuitive representation method. We propose a graphical object query language called GOQL (Graphical Object Query Language) for object databases. By employing simple graphical notations, advanced features of the object queries such as path expressions including set attributes, quantifiers, and/or methods can be represented in a simple graphical notation. GOQL has an excellent expressive power compared with previous graphical object query languages. We show that path expressions in XSQL(1,2) can be represented by the simple graphical notations in GOQL. We also propose an algorithm that translates a graphical query in GOQL into the textual object query with the same semantics. We finally describe implementation results of GOQL in the Internet environments.