• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10a
• /
• pp.46-48
• /
• 2004

Distributed Hash Table(DHT)를 기반으로 하는 structured P2P에서 복잡 질의를 통친 원하는 자료를 찾는 것은 쉽지 않다. 이와 같은 것들 중 하나가 범위 값을 이용하여 원하는 값을 찾는 range query이다. 본 논문에서는 full binary tree의 특징을 이용하여 structured P2P에서 range query를 수행할 수 있는 mapping 함수와, load balance를 지원하기 위한 방법을 제안한다 또한 실험을 통해서 이 방법들이 어느 정도의 성능을 보여주는 지도 살펴본다.

• Journal of Korea Spatial Information System Society
• /
• v.10 no.1
• /
• pp.15-28
• /
• 2008

In ubiquitous sensor networks(USN) environment, it is essential to process region query for user-demand services. Using R-tree is a preferred technique to process region query for in-network query environment. In USN environment, USN middleware must select sensors that transfers region query with accuracy because the lifetime of sensors is that of whole sensor networks. When R-tree is used, however, it blindly passes the region query including non-existent sensors where MBR(Minimum Boundary Rectangle) of R-tree is Intersected by region of query. To solve in this problem, we propose a reconstruction of region query method which is a trie-structured Quad tree in the base station that includes sensors in region of query select with accuracy. We observed that the proposed method delays response time than R-tree, but is useful for reducing communication cost and energy consumption.

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

• The KIPS Transactions:PartD
• /
• v.13D no.3 s.106
• /
• pp.317-324
• /
• 2006

In this paper, we propose a new indexing technique to solve various queries which have a strong good point not only database indexing schema take advantage of converting from semi-structured data to structured data but also performance is more faster than before. We represent structure information of XML document between nodes of tree that additional numbering information which can be bit-stream without modified structure of XML tree. And, We add in indexing schema searching incidental structure information in the process. In Querying schema, we recover ancestor nodes through give information of node using indexing schema in complete path query expression as well as relative path query expression. Therefore, it takes advantage of making derivative query expression with given query. In this process, we recognize that indexing and querying schema can get searched result set faster and more accurate. Because response time is become shorter by bit operating, when query occur and it just needs information of record set earch node in database.

• Journal of Korea Multimedia Society
• /
• v.7 no.5
• /
• pp.601-616
• /
• 2004

Information retrieval systems for structured documents provide multiple levels of retrieval capability by supporting structure-based queries. In order to process structure-based queries for structured documents, information for structural nesting relationship between elements and for element sequence must be maintained. This paper presents four index structures that can process various query types about structures such as structural relationships between elements or element occurrence order. The proposed algorithms are based on the concept of Global Document Instance Tree.

• Journal of KIISE:Databases
• /
• v.34 no.5
• /
• pp.465-472
• /
• 2007

With the recent proliferation of the use of semi-structured data such as XML, it becomes more important to efficiently store and manage the semi-structured data. The XML data can be logically modelled as a rooted tree e.g., the DOM tree. In order to process a query on the XML data, we traverse the tree structure. In this paper we present an algorithm that places the XML data to disk blocks. The proposed algorithm assigns a number to each node of the tree in a bottom-up fashion. Then, the nodes are allocated to disk blocks using the assigned number. The proposed algorithm does not need access pattern information, and provides good performance for any access pattern. The characteristics of the proposed method are presented with analysis. Through experiments, we evaluate the performance of the proposed method.

• Journal of KIISE:Databases
• /
• v.35 no.4
• /
• pp.356-367
• /
• 2008

As XML is gaining unqualified success in being adopted as a universal data representation and exchange format, particularly in the World Wide Web, the problem of querying XML documents poses interesting challenges to database researcher. Several structural XML query processing methods, including XISS and XR-tree, for past years, have been proposed for fast query processing. However, structural XML query processing has the problem of requiring expensive Join cost for twig path query Recently, sequence matching based XML query processing methods, including ViST and PRIX, have been proposed to solve the problem of structural XML query processing methods. Through sequence matching based XML query processing methods match structured queries against structured data as a whole without breaking down the queries into sub queries of paths or nodes and relying on join operations to combine their results. However, determining the structural relationship of ViST is incorrect because its numbering scheme is not optimized. And PRIX requires many processing time for matching LPS and NPS about XML data trees and queries. Therefore, in this paper, we propose efficient sequence matching method u sing the bottom-up query processing for efficient XML query processing. Also, to verify the superiority of our index structure, we compare our sequence matching method with ViST and PRIX in terms of query processing with linear path or twig path including wild-card('*' and '//').

• Journal of Internet Computing and Services
• /
• v.12 no.4
• /
• pp.157-172
• /
• 2011

The latest active studies on distributed OLAP to adopt a distributed environment are mainly focused on DHT P2P OLAP and Grid OLAP. However, these approaches have its weak points, the P2P OLAP has limitations to multidimensional range queries in the cloud computing environment due to the nature of structured P2P. On the other hand, the Grid OLAP has no regard for adjacency and time series. It focused on its own sub set lookup algorithm. To overcome the above limits, this paper proposes an efficient central managed P2P approach for a cloud computing environment. When a multi-level hybrid P2P method is combined with an index load distribution scheme, the performance of a multi-dimensional range query is enhanced. The proposed scheme makes the OLAP query results of a user to be able to reused by other users' volatile cube search. For this purpose, this paper examines the combination of an aggregation cube hierarchy tree, a quad-tree, and an interval-tree as an efficient index structure. As a result, the proposed cloud P2P OLAP scheme can manage the adjacency and time series factor of an OLAP query. The performance of the proposed scheme is analyzed by a series of experiments to identify its various characteristics.

• Journal of KIISE:Databases
• /
• v.32 no.3
• /
• pp.285-296
• /
• 2005

In mobile distributed systems the data on the air can be accessed by a lot of mobile clients. And, we need an indexing scheme in order to energy-efficiently access the data on the wireless broadcast stream. In conventional indexing schemes, they use the values of primary key attributes and construct tree-structured index. Therefore, the conventional indexing schemes do not support content-based retrieval queries such as partial-match queries. In this paper we propose an indexing scheme, called B2V-Tree, which supports partial match queries on wireless broadcast data stream. For this purpose, we construct a tree-structured index which is composed of bit-vectors, where the bit-vectors are generated from data records through multi-attribute hashing.

• The KIPS Transactions:PartD
• /
• v.8D no.2
• /
• pp.145-153
• /
• 2001

The Pyramid-Technique is based on mapping n-dimensional space data into one-dimensional data and expressing it as B-tree ; and by solving the problem of search time complexity the pyramid technique also prevents the effect \"phenomenon of dimensional curse\" which is caused by treatment of hypercube range query in n-dimensional data space. The Spherical Pyramid-Technique applies the pyramid method’s space division strategy, uses spherical range query and improves the search performance to make it suitable for similarity search. However, depending on the size of data and change in dimensions, the two above technique demonstrate significantly inferior search performance for data sizes greater than one million and dimensions greater than sixteen. In this paper, we propose a new index-structured PdR-Tree to improve the search performance for high dimensional data such as multimedia data. Test results using simulation data as well as real data demonstrate that PdR-Tree surpasses both the Pyramid-Technique and Spherical Pyramid-Technique in terms of search performance.