• Journal of Communications and Networks
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• v.7 no.4
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• pp.478-488
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• 2005

To conserve the usage of energy, indexing techniques have been developed in a wireless mobile environment. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, we present the broadcast-based location dependent data delivery scheme (BBS) for dynamic range queries. In the BBS, broadcasted data objects are sorted sequentially based on their locations, and the server broadcasts the location dependent data along with an index segment. Then, we present a data prefetching and caching scheme, designed to reduce the query response time. The performance of this scheme is investigated in relation to various environmental variables, such as the distributions of the data objects, the average speed of the clients, and the size of the service area.

• Journal of KIISE:Databases
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• v.31 no.6
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• pp.664-674
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• 2004

The trajectory preservation property that stores only one trajectory in a leaf node is the most important feature of an index structure, such as the TB-tree for retrieving object's moving paths in the spatio-temporal space. It performs well in trajectory-related queries such as navigational queries and combined queries. But, the MBR of non-leaf nodes in the TB-tree have large amounts of dead space because trajectory preservation is achieved at the sacrifice of the spatial locality of trajectories. As dead space increases, the overlap between nodes also increases, and, thus, the classical range query cost increases. We present a new split policy and entry relocation policies, which have no deterioration of the performance for trajectory-related queries, for improving the performance of range queries. To maximally reduce the dead space of a non-leaf node's MBR, the Maximal Area Reduction (MAR) policy is used as a split policy for non-leaf nodes. The entry relocation policy induces entries in non-leaf nodes to exchange each other for the purpose of reducing dead spaces in these nodes. We propose two algorithms for the entry relocation policy, and evaluate the performance studies of new algorithms comparing to the TB-tree under a varying set of spatio-temporal queries.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.79-81
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• 2004

범위 기반 레이블링 스킴(range-based labeling scheme)을 이용하면 임의의 두 노드에 대한 조상-자손 관계를 쉽게 판별할 수 있으므로, XPath나 XQuery 형태의 질의를 효율적으로 처리할 수 있다. 그러나 노드의 삽입이 일어나는 동적인 상황에서는 불가피하게 전체 또는 일부의 레이블을 다시 할당(re-labeling)할 가능성이 있다는 문제점이 있다. 본 논문에서는 Dietz 레이블링 스킴을 개선한 EP2(extended preorder ＆amp; postorder) 레이블링 스킴을 제안한다. 제안하는 스킴은 동일한 저장 공간상에서 범위 기반 레이블링 스킴에 비해 동적인 갱신에 유리하며, 기존의 구조 조인 알고리즘(structural join algorithm)을 이용하여 효율적으로 구조 질의(structural query)를 처리할 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.107-109
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• 2000

최근에 데이터베이스 혹은 그 응용분야에서 이미지 데이터와 같은 멀티미디어 정보 처리에 대한 관심이 고조되고 있다. 따라서 이미지 데이터를 효율적으로 저장하고, 사용자가 원하는 질의 결과를 신속히 제공하는 것이 중요한 연구분야이다. 본 연구에서는 이미지 데이터에 대한 질의를 처리하기 이한 이미지 데이터로부터의 정보 추출과 데이터 인덱싱 방법에 관하여 논하고, 구축된 인덱싱 구조에 효율적인 질의 처리가 가능하도록 VP(Vantage Point)를 이용하여 영역질의를 처리하는 방법을 제시하였다. 또한 실험을 통하여 제안된 방법의 효율성을 나타내었다.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.32-41
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• 2006

In data-centric networks, various data items, such as temperature, humidity, etc. are sensed and stored in sensor nodes. As these attributes are mostly scalar values and inter-related, multi-dimensional range queries are useful. To process multi-dimensional range queries efficiently in data-centric storage, data addressing is essential. The Previous work focused on efficient query processing without considering overall network lifetime. To prolong network lifetime and support multi-dimensional range queries, we propose a dynamic data distribution method for multi-dimensional data, where data space is divided into equal-sized regions and linearized by using Hilbert space filling curve.

• Journal of Internet Computing and Services
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• v.12 no.6
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• pp.43-51
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• 2011

The recent development of the technology for wireless mobile computing and applied technology for location-based services has made it possible to support query processing faster than that in the past. However, some technological limitations on hardware and software still exist. The most critical aspects of query processing are accuracy and speed. For improving the accuracy, it is required that detailed information on the data involved in query processing be saved. In this case, the amount of information on the data increases, which decreases the speed. On the other hand, for increasing the speed, it is necessary to reduce the broadcast cycle, which enables rapid data acquisition as desired. In this case, because of insufficient index information, the listen time for the client increases, which may cause unnecessary energy consumption. Therefore, a trade-off occurs between the accuracy and speed. This paper proposes a hierarchical bitmap-based spatial index (HBI) as a solution for the aforementioned problems. HBI describes an object with 0 and 1 on the Hilbert curve map. It reduces the broadcast cycle by decreasing the index size on the basis of bit information and tree structure. Therefore, it is able to shorten the listen time and query processing time. In addition, HBI enables the detection of the locations of all the objects so that it is possible selectively listen to a broadcast. A performance evaluation of the proposed technique demonstrates that it is excellent.

• Journal of Korea Spatial Information System Society
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• v.10 no.3
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• pp.1-18
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• 2008

Because we can usually get many information through analyzing trajectories of moving objects on spatial networks, efficient trajectory index structures are required to achieve good retrieval performance on their trajectories. However, there has been little research on trajectory index structures for spatial networks such as FNR-tree and MON-tree. Also, because FNR-tree and MON-tree store the segment unit of moving objects, they can't support the trajectory of whole moving objects. In this paper, we propose an efficient trajectory index structures based on signatures on a spatial network, named SigMO-Tree. For this, we divide moving object data into spatial and temporal attributes, and design an index structure which supports not only range query but trajectory query by preserving the whole trajectory of moving objects. In addition, we divide user queries into trajectory query based on spatio-temporal area and similar-tralectory query, and propose query processing algorithms to support them. The algorithm uses a signature file in order to retrieve candidate trajectories efficiently Finally, we show from our performance analysis that our trajectory index structure outperforms the existing index structures like FNR-Tree and MON-Tree.

• Journal of KIISE:Databases
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• v.34 no.4
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• pp.315-327
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• 2007

The performance of database applications with large sets of multidimensional data depends on the performance of its access methods and the underlying disk system. In modeling the disk system, even though modem disks are manufactured with multiple physical zones, conventional access methods have been developed based on a traditional disk model with many simplifying assumptions. Thus, there is a marked lack of investigation on how to enhance the performance of access methods given a zoned disk model. The paper proposes novel zoning techniques that can be applied to any multidimensional access methods, both static and dynamic, enhancing the effective data transfer rate of underlying disk system by fully utilizing its zone characteristics. Our zoning techniques include data placement algorithms for multidimensional index structures and accompanying localized query processing algorithms for range queries. The experimental results show that our zoning techniques significantly improve the query performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3183-3192
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• 2009

The purpose of this paper is to introduce Naming application model for sensor networks. Currently, sensor networks comprised of sensor nodes have provided an application range which could not function before. However, unlike general network, current sensor networks are designed to cooperate with major wireless-capable sensor devices with limited resources. Thus, exporting/importing between individual sensor and current sensor networks is very inefficient and unstable. Attribute, schema and DIT(Directory Information Tree) must be designed for sensor network using SN LDAP application model in order to maintain transparency and provide constant service in a situation of data defect. With the system explained as above, Naming application model is made to manage SN Fuzzy Query. It shall be more efficient and stable structure as long as Naming application using a virtual equation in a certain environment with information collected from sensor node is provided. In this paper, I would like to introduce SN Fuzzy LDAP model for sensor network by quick Naming method. Also, naming application which is possible for fuzzy query in a certain environment based on the system will be proved.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.4
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• pp.1-14
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• 2004

In this study, we propose Linktable based on extended TB-Tree(LTB-Tree) which can improve the performance of existing TB (Trajectory-Bundle)-tree proposed for indexing the trajectory of moving objects in GIS Applications. In addition, in order to evaluate proposed indexing scheme, we take into account as follows. At first, we select existing R*-tree, TB-tree, and LTB-tree as the subject of performance evaluation. Secondly, we make use of random data set and real data set as experimental data. Thirdly, we evaluate the performance with respect to the variation of size of memory buffer by considering the restriction of available memory of a given system. Fourth, we test them by using the experimental data set with a variation of data distribution. Finally, we think over insertion and retrieval performance of trajectory query and range query as experimental measures. The experimental results show that the proposed indexing scheme, LTB-tree, gains better performance than traditional other schemes with respect to the insertion and retrieval of trajectory query.