• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2696-2707
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• 2009

Although, a number of DBMS vendors are scrambling to extend their products to handle XML, there is a need for a lightweight, DBMS and platform-independent XML repository as well. In this paper, we describe such an XML integrated repository system, that solves the following functions : generating relational schema from XML DTDs for storage of XML documents, importing data from XML documents into relational tables, creating XML documents according to a XMLQL(XML Query Language) from data extracted from a database and synchronizing the replicated XML documents. In the XML repository systems, the efficient change detection techniques for XML documents is required to maintain the consistency of replicated XML data because the same data in the repository can be replicated between so many different XML documents. In this paper, we propose a message digest based change detection technique to maintain the consistency of replicated data between client XML documents and a XML data in XML repository systems.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.39-42
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• 2000

Extensible Markup Language(XML) is fast emerging as the dominant standard for representing data in the World Wide Web. Sophisticated query engines that allow users to effectively tap the data stored in XML documents will be crucial to exploiting the full power of XML. While there has been a great deal of activity recently proposing new semi-structured data models and query languages for this purpose, this paper explores the more conservative approach of using traditional relational database engines for processing XML documents conforming to Document Type Descriptors(DTDs). In this paper, we describe how to generate relational schemas from XML DTDs. The main issues that must be addressed inc]ode (a) dealing with the complexity of DTD element specifications (b) resolving the conflict between the two-level nature of relational schemas (table and attribute) vs. the arbitrary nesting of XML DTD schemas and (c) dealing with set-valued attributes and recursion. We now propose a set of transformations that can be used to "simplify" any arbitrary DTD without undermining the effectiveness of queries over documents conforming to that DTD.

• Journal of KIISE:Databases
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• v.33 no.5
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• pp.513-525
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• 2006

Search results of XML keyword search are defined generally as the most specific elements containing all query keywords in the literature. The labels of XML elements and semantic information such as ontology, conceptual model, thesaurus, and so on, are used to improve the preciseness of the search results. This paper presents a hierarchical index for an efficient XML keyword query processing on the condition that returnable search concepts are defined and users' query concepts can be interpreted with the help of the semantic information. The hierarchical index separately stores the XML elements containing a keyword on the basis of the hierarchical relations of the concepts that the XML elements belong to, and makes it possible to obtain least common ancestors, which are candidates for the search results, with selectively reading the elements belonging to the concepts relevant to query concepts and without considering all the combinations of the elements having been read. This paper deals with how to organize the hierarchical index and how to process XML keyword queries with the index. In our experiment with the DBLP XML document and the XML documents in the INEX2003 test set, the hierarchical index worked well.

• Proceedings of the Korea Database Society Conference
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• 2000.11a
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• pp.95-100
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• 2000

사실 표준 XQL(XML Query Language) 기반의 문서 질의를 이용하여 XML 문서에 대한 구조 검색과 내용 검색을 위한 문서검색 시스템을 구성하였다. 즉 XML 문서를 파징하여 내용 및 구조 정보를 트리구조로 구성하고, 표준 XQL을 이용하여 트리 구조 정보에 질의함으로서 구조 및 내용 검색을 하도록 구현하였다. 이를 이용한 응용분야로는 향후 방대한 크기의 XML문서 검색과 문서 관리, 전자 상거래 등 다양한 분야에 활용될 수 있는 요소기술로서 기대된다.

• The KIPS Transactions:PartD
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• v.9D no.5
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• pp.789-800
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• 2002

XML is a standard format of web data and is currently used as a prevailing language for exchanging data. Most of the commercial data are stored in a relational database. It is quite important to convert these conventionally stored data into those for exchange and use them in data exchange, or to get the query results effectively by utilizing XQL on XML data which are store in a relational database. Thus, it is absolutely required to have a proper query processing mechanism for XML data and to maintain many XML data properly. Up to now, many cases of researches on the storage and retrieval of XML data have been carried out and under study. But, effective retrieval and storage system for path queries like XQL has yet to be contrived. Thus, in this paper, a schema to store XML data is designed, in which DFS-Numbegering method is used to store data effectively. And an effective path query processing method is also designed and implemented, in which a traditional relational database engine is used. That is, XQL is converted into SQL with a XQL processor if a user makes query XQL in a system. A database system executes SQL, and a XML generator uses a generated record and makes a XML document.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.124-126
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• 2005

XML 문서로부터 정보를 검색하거나 추출하기 위해 쓰이는 질의 표준으로 XQuery 제안되었다. 하지만 사용자들이 XQuery를 사용하기 위해서는 XML문서의 구조를 알아야만 한다는 단점을 가지고 있다. 이에 문서 구조에 의존하지 않는 질의인 CXQuery가 제안되었지만 CXQuery가 XML을 파싱하여 DBMS에 저장한 뒤 DBMS에서 질의를 처리하기 때문에 XML문서를 직접 처리하지 못하고 한 단계 변환의 과정을 필요로 한다는 단점을 가지고 있다. 이 논문에서는, 사용자가 질의한 CXQuery를 그에 해당하는 XQuery로 변환하는 변환기를 개발함으로써 CXQuery의 문서 구조 독립적인 질의가 용이 하도록 하고 XML문서에 대해 직접적으로 질의 처리가 가능하도록 하였다.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.178-190
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• 2009

XML is recommended by W3C(World Wide Web) and widely accepted as a standard markup language for expression and sharing data. Recently, increasing the use and the amount of XML documents, there is required that easy methods for accessing XML documents at anytime and anywhere, therefore, the distributed XML repository systems is developed. For this, distributed XML repository systems is necessary to research catalog management schemes. In this paper, we design distributed XML database model considering CPU costs, I/O costs, concurrency control, two-phase commits a protocol, queuing delay and so on. And we implement a simulator in order to execute performance evaluation centralized catalog method, fully replicated catalog method, and partitioned catalog method using reasonably setting up environments.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.905-913
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• 2008

Many heterogeneous XML documents are being widely used with the increasing employment of XML, and the importance of data structure research for more efficient document management has been growing steadily. We propose a query processing technique which uses parent node information in a partitioned inverted index tree. The searching efficiency of these heterogeneous documents is greatly influenced by the number of query processing and the amount of target data sets in many ways. Therefore, considering these two factors is very important for designing a data structure. First, our technique stores parent node's information in an inverted index table. Then using this information, we can reduce the number of query processing by half. Also, the amount of target data sets can be lessoned by using partitioned inverted index table. Some XML documents collected from the Internet will be used to demonstrate the new method, and its high efficiency will be compared with some of the existing searching methods.

• 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.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.578-589
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• 2006

Owing to the proliferation of Radio Frequency Identification (RFID) technologies which is being watched as a core technology of ubiquitous computing, applications which offer convenience to people using RFID technologies are more and more increased. To easily develop these applications, a middleware system which acts as a bridge between RFID hardware and application is essential. In this paper, we propose a novel XML-based RFID middleware system called UbiCore (Ubiquitous Core). UbiCore has following features: First, UbiCore employs its own query language called XQueryStream (XQuery for Stream Data) which is originated from XQuery. Second, UbiCore has the preprocessing phase called pre-filtering prior to query evaluation and reuses the intermediate result of previous evaluation to speed up the processing of RFID tag data stream. Third, UbiCore supports query on both continuously generated stream data and archived historical data. And last, UbiCore offers a distinct markup language called Context-driven Service Markup Language (CSML) to easily specify the linking information between context and service.