• Title/Summary/Keyword: Tree join

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A Tree-structured XPath Query Reduction Scheme for Enhancing XML Query Processing Performance (XML 질의의 수행성능 향상을 위한 트리 구조 XPath 질의의 축약 기법에 관한 연구)

  • Lee, Min-Soo;Kim, Yun-Mi;Song, Soo-Kyung
    • The KIPS Transactions:PartD
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    • v.14D no.6
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    • pp.585-596
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    • 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.

Multicast Secure Architecture based on PIM-SM (소규모 멀티캐스트를 기반으로 한 멀티캐스트 보안구조)

  • 김성선;이상순;정영목
    • Journal of the Korea Society of Computer and Information
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    • v.6 no.2
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    • pp.116-122
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    • 2001
  • A conventional multicast secure protocol. MVMRP, CBT is designed for a large scaled r protocol so the PIM-SM (protect Independent Multicst-Sparse Mode) routing protocol which small number of clients, long distance path among the hosts and shortest path routing chara weak point of require it's own Core tree and re-keying when the traffic is pass through the ro In this study, proposes a architect for a licit information secure of join/leave to all the user or on-service user. With proposed architect, subgroups for multicast secure group mana will be divided by RP (Rendezvous-Point) unit and each RP has a subgroup manager. As a result, the transmitting time is shortened because there is no need to data translation by group key on data sending and the whole architecture size is samller than the other multicast secure architecture.

Energy Efficiency Routing Algorithm for Vessel Ubiquitous Sensor Network Environments (선박 USN에서 에너지 효율성을 위한 라우팅 알고리즘)

  • Choi, Myeong-Soo;Pyo, Se-Jun;Lee, Jin-Seok;Yoon, Seok-Ho;Lee, Seong-Ro
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5B
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    • pp.557-565
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    • 2011
  • In this paper, we assume that sensor nodes organize the multi-hop networks, are fixed, and operate as full function devices(FFD). The wireless sensor network(WSN) only consists of mobile nodes without the assistance from the fixed infrastructure, which increases the flexibility of the network. However, it is difficult to perform routing in the WSN, since sensor nodes freely join in and drop out of the network, and some sensor nodes have very low power. We propose the algorithm combining routing schemes based on the bitmap and cluster methods in this paper. Through computer simulations, we show the validity of the proposed algorithm.

Parallel Pipelined Spatial Join Method for Efficient Query Processing In Distributed Spatial Database Systems (분산 공간 데이터베이스 시스템에서의 효율적인 질의 처리를 위한 병렬 연쇄 공간 죠인 기법)

  • Ko, Ju-Il;Lee, Hwan-Jae;Kim, Myoung-Keun;Lee, Soon-Jo;Bae, Hae-Young
    • Annual Conference of KIPS
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    • 2002.04a
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    • pp.11-14
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    • 2002
  • 분산 공간 데이터베이스 시스템에서 자주 수행되는 공간 죠인 질의는 공간 데이터의 특징인 대용량성과 복잡성으로 인하여 공간 연산 수행시 연간을 수행하는 서버의 CPU 및 디스크 I/O상의 과부하를 일으킨다. 본 논문은 이러한 분산 광간 데이터베이스 시스템에서 수행 비용이 많이 드는 원격 사이트간의 공간 죠인 질의를 병렬적이며 연쇄적으로 수행하는 기법을 제안한다. 본 기법은 공간 죠인 연산의 대상이 되는 릴레이션들을 공간 연산의 특성에 따라 순서화하고, 그 중 최하위의 죠인에 참여하는 릴레이션들 중 하나를 이등분 하는 방법으로 공간 죠인 연산을 분리한 추, 질의 수행에 참여하는 두 서버에게 죠인 연산을 분배한다. 각 서버는 분할된 공간 죠인 연산을 동시에 연쇄적으로 저리하고 결과를 병합하여 최종 죠인 결과를 생성한다. 본 기법은 릴레이션을 분할하여 죠인을 수행함으로써 공간 연산에 참여하는 객체의 수를 절반으로 줄이며 R-Tree 등의 공간 인덱스 탐색 횟수와 그 범위를 감소시킨다. 또한 연쇄적인 질의 처리로 죠인의 결과인 임시 릴레이션을 생성하지 않으므로 대용량의 데이터에 대한 복잡한 질의에 대해서도 제한 없이 수행한다.

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Mobile Multicast Method using the User Pattern (사용자 성향에 기반한 이동 멀티캐스트 기법)

  • Sung Sulyun;Jeon Jinyong;Seo Yuhwa;Shin Yongtae
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.1A
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    • pp.46-54
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    • 2005
  • This paper presents an effcient mobile multicast method using the user pattern. We exploit the repetitive movement pattern of mobile node to reduce the total number of experience of graft and join procedure. We defined the locality scope by a movement pattern. While the network is included in the locality scope, the network should maintain a multicast tree even when the mobile node moves to the other network. In this way, the mobile host can receive a multicast service without a delay when it moves to the network in the locality scope later. We compare our scheme with existing schemes under the total signaling cost and the service delay time by using a discrete analytical model for cost analysis. Analytical results demonstrated that the total signaling cost and service delay time was significantly reduced through our proposed scheme.

Handoff Scheme to support Multicast in IPv6 (IPv6에서 멀티캐스트 지원을 위한 핸드오프 기법)

  • Kim, Ki-Young
    • Journal of the Korea Society of Computer and Information
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    • v.10 no.4 s.36
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    • pp.285-293
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    • 2005
  • Whenever mobile node moves a new domain in multicast environments. Both handoff and join multicast group always occur. These procedures take a much of delay time and lost the packets in flight. Handoff delay is a significant factor fot the QoS of mobile node in mobile environments. In this paper. we propose a new handoff scheme which supports multicast and guarantees a low handoff delay in IPv6. The scheme makes adjacent subnets the member of multicast tree. After that, this eliminates packet loss and reduces the handoff delay time. Simulation shows that the proposed scheme takes a low delay and lower packet loss rate than the remote-subscription scheme.

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A Multicast Delivery Technique for VCR-like Interactions in Collaborative P2P Environment (협력 P2P 환경에서 VCR 기능을 위한 멀티캐스트 전송 기법)

  • Kim Jong-Gyung;Kim Jin-Hyuk;Park Seung-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.7B
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    • pp.679-689
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    • 2006
  • Delivering multicast stream is one of the cost-saving approach in the large scale VOD environment. Because implementing VCR-like interactions for user's convenience in the multicast streaming system involves complex problems, we need the proper solutions for them. In this paper, we propose a hybrid scheme which uses the general P2P and the patching scheme with the Collaborative Interaction Streaming Scheme(CISS). CISS provides jumping functionability to the appropriate multicast session after VCR-like interaction in the environment in which multiple peers transmit VCR-like interaction streams to the VCR-like functionability request node to reduce the loads generated by frequent join or departure of peers at the multicast tree during providing VCR-like functionability. Therefore, with the proposed scheme we can distribute network traffic and reduce control overhead and latency. And to evaluate the performance of proposed scheme we compare it in the aspect of the performance of streaming delivery topology, control overhead and streaming quality with P2Cast[10] and DSL[11]. The simulation result shows that proposed P2Patching reduces about 30% of process overhead and enhances about 2530 of streaming quality compared with DSL.

An Efficient Sequence Matching Method for XML Query Processing (XML 질의 처리를 위한 효율적인 시퀀스 매칭 기법)

  • Seo, Dong-Min;Song, Seok-Il;Yoo, Jae-Soo
    • Journal of KIISE:Databases
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    • v.35 no.4
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    • pp.356-367
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    • 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 '//').

Applicability of Geo-spatial Processing Open Sources to Geographic Object-based Image Analysis (GEOBIA)

  • Lee, Ki-Won;Kang, Sang-Goo
    • Korean Journal of Remote Sensing
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    • v.27 no.3
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    • pp.379-388
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    • 2011
  • At present, GEOBIA (Geographic Object-based Image Analysis), heir of OBIA (Object-based Image Analysis), is regarded as an important methodology by object-oriented paradigm for remote sensing, dealing with geo-objects related to image segmentation and classification in the different view point of pixel-based processing. This also helps to directly link to GIS applications. Thus, GEOBIA software is on the booming. The main theme of this study is to look into the applicability of geo-spatial processing open source to GEOBIA. However, there is no few fully featured open source for GEOBIA which needs complicated schemes and algorithms, till It was carried out to implement a preliminary system for GEOBIA running an integrated and user-oriented environment. This work was performed by using various open sources such as OTB or PostgreSQL/PostGIS. Some points are different from the widely-used proprietary GEOBIA software. In this system, geo-objects are not file-based ones, but tightly linked with GIS layers in spatial database management system. The mean shift algorithm with parameters associated with spatial similarities or homogeneities is used for image segmentation. For classification process in this work, tree-based model of hierarchical network composing parent and child nodes is implemented by attribute join in the semi-automatic mode, unlike traditional image-based classification. Of course, this integrated GEOBIA system is on the progressing stage, and further works are necessary. It is expected that this approach helps to develop and to extend new applications such as urban mapping or change detection linked to GIS data sets using GEOBIA.

An efficient Multicast Delivery Mechanism Based on Locality in Mobile IPv6 Networks (이동 IPv6 환경에서 지역성에 기반한 효율적인 멀티캐스트 전송 메커니즘)

  • Sung Sulyun;Kim Kiyoung;Shin Yongtae
    • The KIPS Transactions:PartC
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    • v.12C no.3 s.99
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    • pp.409-418
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    • 2005
  • This paper presents an efficient multicast method based on a locality in mobile IPv6 networks. We exploit the repetitive movement pattern of mobile node to reduce the total number of experience of graft and join procedure. We defined the locality scope by a movement pattern. While the network is included in the locality scope, the network should maintain a multicast tree even when the mobile node moves to the other network. In this way, the mobile host can receive a multicast service without a delay when it moves to the network in the locality scope later. We compare our scheme with existing schemes under the total signaling cost and the service delay time by using a discrete analytical model for cost analysis. Analytical results demonstrated that the total signaling cost and service delay time was significantly reduced through our proposed scheme.