• Journal of KIISE:Databases
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• v.30 no.5
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• pp.532-539
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• 2003

The paper proposes a pre-processing method for efficient processing of XML queries in information retrieval systems with a large amount of XML documents. For the pre-processing, we use a signature-based approach. In the conventional (flat document-based) information retrieval systems, user queries consist of keywords and boolean operators, and thus signatures are structured in a flat manner. However, in XML-based information retrieval systems, the user queries have the form of path query. Therefore, the flat signature cannot be effective for XML documents. In the paper, we propose a structured signature for XML documents. Through experiments, we evaluate the performance of the proposed method.

• 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.36 no.3
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• pp.180-188
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• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.63-66
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• 2002

XML 저장소 내에 XML 문서들과 그들로부터 도출된 XML 실체뷰가 있다고 가정할 때, XML 문서 검색의 성능 향상을 위해서 이들 실체뷰를 이용하여 질의를 처리할 수 있다. 즉, 하부 XML 문서에 대한 원래의 질의를 관련된 실체뷰에 대한 질의로 변환하여 수행함으로써 질의 응답시간을 줄일 수 있다. 실체뷰를 이용한 질의 처리의 유형으로는 (1) 실체뷰로부터 원하는 결과를 모두 얻을 수 있는 유형과 (2) 질의 결과의 일부는 실체뷰에 존재하지만 일부는 하부 XML 문서로부터 검색해야 하는 유형이 있다. 본 논문에서는 두번째 유형에 대하여 연구하였다. 주어진 질의를 (1) 실체뷰에 대한 질의와 하부 데이타에 대한 질의로 분할하여 처리한 후 두 결과를 통합하는 방법과 (2) 원래의 질의를 실체뷰를 이용하지 않고 처리하는 방법 간의 성능을 비교, 분석하였다.

• Journal of KIISE:Databases
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• v.30 no.1
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• pp.27-40
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• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.178-180
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• 2005

지금까지 제안된 XML 문서상의 분기 질의(twig query) 처리 기법들의 중요한 흐름 중 하나는 지역 인코딩 기법을 이용하는 것이다. 하지만 이 기법에 기반한 분기 질의 처리는 분기 질의상의 단말 노드와 분기 노드의 엘리먼트를 반드시 읽어야 하는 단점이 있다. 그러나 지역 인코딩 기법과는 달리 경로 정보를 축약하는 방식의 레이블링 기법(예: 듀이 인코딩)은 지역 인코딩에 의한 레이블에 비해 더 많은 정보를 담고 있어서, 이 기법과 구조 인덱스를 이용하여 XML 문서를 인덱싱하면 질의상의 단말 태그의 엘리먼트만을 읽어도 분기 질의를 처리할 수 있다. 이를 이용하여, 본 논문에서는 경로 정보 축약 레이블링 기법과 구조 인덱스를 이용한 분기 질의 처리 기법을 제안한다. 제안된 알고리즘은 디스크 입출력을 줄일 수 있으며 불필요한 중간 결과도 생성하지 않는다.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.473-486
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• 2005

The Hippocratic database model recently proposed by Agrawal et at. incorporates privacy protection capabilities into relational databases. The authors have subsequenty proposed the Hippocratic XML daかabase model[4], an extension of the Hippocratic database model for XML databases. In this paper, we propose a new concept that we cail the dynamic predicate(DP) for effective access control in the Hippocratic XML database model. A DP is a novel concept that represents a dynamically constructed rendition that tan be adapted for determining the accessibility of elements during query execution. DPs allow us to effectively integrate authorization checking into the query plan so that unauthorized elements are excluded in the process of query execution. Using synthetic and real data, we have performed extensive experiments comparing query processing time with those of existing access control mechanisms. The results show that the proposed access control mechanism improves the wall clock time by up to 219 times over the top-down access control strategy and by up to 499 times over the bottom-up access control strategy. The major contribution of our, paper is enabling effective integration of access control mechanisms with the query plan using the DP under the Hippocratic XML database model.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.711-720
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• 2000

BADA-IV/XML is a system designed specifically for managing XML. Documents and is essential to various electronic document applications as a fundamental system. BADA-IV/XML supports all of aspects of data model, querying and manipulation operations for managing XML documents. This paper provides an overview of these aspects of the BADA-IV/XML, as well as defines schema classes for stroing, querying and maintaining hierarchical semantics of multimedia documents and structural semantics of complex documents linked with each other, Also a multimedia document query language is designed and implemented to support essential operations for efficient searching and managing multimedia documents. Finally, some simulation results show the performance of the paged VF(Virtual Fragmentation) model and the search model using element's identifier as compared with a general model.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.7-8
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• 2007

• Journal of KIISE:Databases
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• v.36 no.1
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• pp.50-62
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• 2009

In wireless and mobile environments, data broadcasting is recognized as an effective way for data dissemination due to its benefits to bandwidth efficiency, energy-efficiency, and scalability. In this paper, we address the problem of delayed query processing raised by tree-based index structures in wireless broadcast environments, which increases the access time of the mobile clients. We propose a novel distributed index structure and a clustering strategy for streaming XML data which enable energy and latency-efficient broadcast of XML data. We first define the DIX node structure to implement a fully distributed index structure which contains tag name, attributes, and text content of an element as well as its corresponding indices. By exploiting the index information in the DIX node stream, a mobile client can access the wireless stream in a shorter latency. We also suggest a method of clustering DIX nodes in the stream, which can further enhance the performance of query processing over the stream in the mobile clients. Through extensive performance experiments, we demonstrate that our approach is effective for wireless broadcasting of XML data and outperforms the previous methods.