• Proceedings of the Korean Information Science Society Conference
• /
• 2005.07b
• /
• pp.220-222
• /
• 2005

XQuery는 계층적 구조를 가지는 XML 문서를 검색하기 위한 질의 언어이다. 이에 관한 연구들로는 XML SPY, Stylus studio와 같은 여러 XML 기반 XQuery 지원 툴들이 상용화 되어 있다. 하지만 보다 쉽고 직관적으로 XQuery를 작성하고 적용 시킬 수 있는 툴들은 미흡한 것이 사실이다. 이 논문에서는 XML을 문서를 직관적인 구조로 표현해주며 최종 사용자의 관점에 맞추어 XQuery를 생성을 지원하는 시스템을 설계 구현하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10c
• /
• pp.22-24
• /
• 2002

XML이 웹상에서 데이타 교환의 표준으로 채택되면서 XML 데이타를 관계형 데이타베이스를 이용하여 저장하고 처리하는 것이 많이 연구되고 있다. 본 연구에서는 관계형 데이타베이스에 저장되어 있는 XML 데이타의 효과적인 질의 처리에 사용할 수 있는 인덱스 구조로서 디렉토리 인덱스를 제안한다. 디렉토리 인덱스는 정규 경로식 처리에 있어서 비트맵을 이용하여 조인 연산을 크게 줄여 처리 시간이 빠르며 인덱스의 갱신에도 효과적으로 대처할 수 있다.

• The KIPS Transactions:PartD
• /
• v.12D no.3 s.99
• /
• pp.439-446
• /
• 2005

XML is the standard that can manage systematically WWW documents and increase retrieval efficiency. Because XML documents have the information of contents and that of structure in single document, users can get more suitable retrieval result by retrieving the information of content as well as that of logical structure. In this paper, we will propose a method to calculate the weights of XML tags so that the information of XML tag is used to index decision. A proposed method creates term vector and weight vector for XML tags, and calculates weight of tag by reflecting user's retrieval behavior (user's query). And it decides the weights of index terms of XML document by reflecting the weights of tags. And we will perform an evaluation of proposed method by comparison with existing researches using weights of paragraphs.

• Journal of KIISE:Databases
• /
• v.36 no.3
• /
• pp.180-188
• /
• 2009

Recently, the needs for an efficient and secure access control method of dynamic XML data in a ubiquitous data streams environment have become an active research area. In this paper, we proposed an improved role-based prime number labeling scheme for an efficient and secure access control labeling method in dynamic XML data streams. And we point out the limitations of existing access control and labeling schemes for XML data assuming that documents are frequently updated. The improved labeling method where labels are encoded ancestor-descendant and sibling relationships between nodes but need not to be regenerated when the document is updated. Our improved role-based prime number labeling scheme supports an infinite number of updates and guarantees the arbitrary nodes insertion at arbitrary position of the XML tree without label collisions. Also we implemented an efficient access control using a role-based prime number labeling. Finally, we have shown that our approach is an efficient and secure through experiments.

• Journal of KIISE:Software and Applications
• /
• v.32 no.6
• /
• pp.554-569
• /
• 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
• /
• v.30 no.1
• /
• pp.27-40
• /
• 2003

The inverted index widely used in the existing information retrieval field should be extended for XML documents to support containment queries by XML information retrieval systems. In this paper, we consider that there are two methods in storing the inverted index and processing containment queries for XML documents as the previous work suggested: using a RDBMS or using an inverted lift engine. It has two drawbacks to extend the inverted index in the previous work. One is that using a RDBMS is moth worse in the performance than using an inverted list engine. The other is that when containment queries are processed in a RDBMS, there is an increase in the number of a join operation as the path length of a query increases and a join operation always happens between large fables. In this paper. we extend the inverted index in a different way to solve these problems and show the effectiveness of using a RDBMS.

• Journal of Information Technology and Architecture
• /
• v.10 no.1
• /
• pp.123-135
• /
• 2013

This paper presents a two-dimensional grouping index(2DG-index) for efficient processing of XML filtering queries. Recently, many index techniques have been suggested for the efficient processing of structural relationships among the elements in the XML database such as an ancestor- descendant and a parent-child relationship. However, these index techniques focus on simple path queries, and don't consider the path queries that include a condition value for filtering. The 2DG-index is an index structure that deals with the problem of clustering index entries in the twodimensional domain space that consists of a XML path identifier domain and a filtering data value domain. For performance evaluation, we have compared our proposed 2DG-index with the conventional one dimensional index structure such as the data grouping index (DG-index) and the path grouping index (PG-index). As the result of the performance evaluations, we have verified that our proposed 2DG-index can efficiently support the query processing in XML databases according to the query types.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.35-38
• /
• 2005

1998년 XML 문서 표준이 제안된 이래, 다양한 응용 분야에서 XML은 데이터를 표현하는 표준으로 자리잡아 가고 있다. 특히, 인터넷상의 많은 데이터들이 XML 형태로 작성되고 변환됨에 따라 다량의 XML 데이터가 생성되고 있다. 따라서 현재 XML 문서의 저장 및 질의 처리 기법의 연구가 활발하게 진행되고 있다. 하지만 기존의 연구는 대용량 XML 문서를 다루기에는 미흡한 점이 있다. 본 논문에서는 인터넷상의 널리 퍼져있는 방대하고, 다양한 구조의 XML문서들을 대상으로 패스 기반 질의를 빠르게 처리할 수 있는 검색 기법을 제안한다. 제안된 기법은 인터넷상에 산재해 있는 여러 XML 문서를 관계형 데이터베이스에 효율적으로 저장하고 질의를 통해 인터넷상 XML 문서의 엘리먼트를 빠르게 검색하는데 주안점을 둔다. 먼저, XML 문서를 관계형 데이터베이스에 효율적으로 저장하는 계층형 XML 저장 기법을 제안하고, 정보 검색 시스템에서 많이 사용하는 역 인덱스를 사용하여 저장된 XML 문서에 대한 검색 성능을 향상시킨다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2000.10a
• /
• pp.93-96
• /
• 2000

XML은 차세대 인터넷 전자 문서 표준으로서 주목을 받고 있다. 최근에 기존의 문서를 XML로 변환하거나 신규 문서를 XML로 작성하게 되면서 대량의 XML 문서가 생성되고 있고, 따라서 대량의 XML 문서를 효율적으로 검색하기 위한 XML 문서 검색기가 필수적 시스템으로 부각되고 있다. 본 논문에서는 XML 문서에 대한 내용기반, 구조기반, 속성기반 검색을 지원하는 XML과 객체지향데이터베이스 표준언어인 OQL 을 결합한 형태의 XML 질의 언어를 설계하고, 한국전자통신연구원에서 개발한 바다-IV 내에 저장된 XML 문서에 대해 검색을 수행하는 바다-IV/XML 검색기의 설계 및 구현에 대하여 기술하였다.

• Journal of KIISE:Databases
• /
• v.32 no.4
• /
• pp.441-451
• /
• 2005

HTML is mostly stored in native file systems instead of specialized repositories such as a database. Like HTML, XML, the standard for the exchange and the representation of data in the Internet, is mostly resident on native file systems. However. since XML data is irregular and verbose, the disk space and the network bandwidth are wasted compared to those of regularly structured data. To overcome this inefficiency of XML data, the research on the compression of XML data has been conducted. Among recently proposed XML compression techniques, some techniques do not support querying compressed data, while other techniques which support querying compressed data blindly encode data values using predefined encoding methods without considering the types of data values which necessitates partial decompression for processing range queries. As a result, the query performance on compressed XML data is degraded. Thus, this research proposes an XML compression technique which supports direct and efficient evaluations of queries on compressed XML data. This XML compression technique adopts an encoding method, called dictionary encoding, to encode each tag of XML data and applies proper encoding methods for encoding data values according to the inferred types of data values. Also, through the implementation and the performance evaluation of the XML compression technique proposed in this research, it is shown that the implemented XML compressor efficiently compresses real-life XML data lets and achieves significant improvements on query performance for compressed XML data.