• Journal of Korea Spatial Information System Society
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• 제8권2호
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• pp.13-38
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• 2006

Range query is one of the most important operations for spatial objects, it retrieves all spatial objects that overlap a given query region in multi-dimensional space. The DOT(DOuble Transformation) is known as an efficient indexing methods, it transforms the MBR of a spatial object into a single numeric value using a space filling curve, and stores the value in a $B^+$-tree. The DOT index is possible to be employed as a primary index for spatial objects. However, the range query processing based on the DOT index requires much overhead for spatial transformations to get the query region in the final space. Also, the detailed range query processing method for 2-dimensional spatial objects has not been studied yet in this paper, we propose an efficient multi-dimensional range query processing technique based on the DOT index. The proposed technique exploits the regularities in the moving patterns of space filling curves to divide a query region into a set of maximal sub-legions within which space filling curves traverse without interruption. Such division reduces the number of spatial transformations required to perform the range query and thus improves the performance of range query processing. A visual simulator is developed to show the evaluation method and the performance of our technique.

• The Transactions of the Korea Information Processing Society
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• 제6권9호
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• pp.2294-2304
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• 1999

Our research purpose in this paper is to improve the performance of query processing in GIS(Geographic Information System) by enhancing the I/O performance exploiting parallel I/O and efficient disk access. By packing adjacent spatial data, which are very likely to be referenced concurrently, into one block or continuous disk blocks, the number of disk accesses and the disk access overhead for query processing can be decreased, and this eventually leads to the I/O time decrease. So, in this paper, we proposes EPR(Enhanced Parallel R-tree) indexing method which integrates the parallel I/O method of the previous Parallel R-tree method and a packing-based clustering method. The major characteristics of EPR method are as follows. First, EPR method arranges spatial data in the increasing order of proximity by using Hilbert space filling curve, and builds a packed R-tree by bottom-up manner. Second, with packing-based clustering in which arranged spatial data are clustered into continuous disk blocks, EPR method generates spatial data clusters. Third, EPR method distributes EPR index nodes and spatial data clusters on multiple disks through round-robin striping. Experimental results show that EPR method achieves up to 30% or more gains over PR method in query processing speed. In particular, the larger the size of disk blocks is and the smaller the size of spatial data objects is, the better the performance of query processing by EPR method is.

• Journal of the Korea Society of Computer and Information
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• 제20권5호
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• pp.1-12
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• 2015

NAND flash memory has being used for storage systems widely, because it has good features which are low-price, low-power and fast access speed. However, NAND flash memory has an in-place update problem, and therefore it needs FTL(flash translation layer) to run for applications based on hard disk storage. The FTL includes complex functions, such as address mapping, garbage collection, wear leveling and so on. Futhermore, implementation of the FTL on low-power embedded systems is difficult due to its memory requirements and operation overhead. Accordingly, many index data structures for NAND flash memory have being studied for the embedded systems. Overall performances of the index data structures are enhanced by a decreasing of page write counts, whereas it has increased page read counts, as a side effect. Therefore, we propose an index management method using a page mapping log table in $B^+$-Tree based on NAND flash memory to decrease page write counts and not to increase page read counts. The page mapping log table registers page address information of changed index node and then it is exploited when retrieving records. In our experiment, the proposed method reduces the page read counts about 61% at maximum and the page write counts about 31% at maximum, compared to the related studies of index data structures.

• Journal of the Korea Society of Computer and Information
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• 제25권10호
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• pp.1-14
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• 2020

In this paper, we propose to solve the problem of increasing system memory usage due to an increase in the number of mapping information management when using a NAND flash memory-based storage device in an existing sector-based file system. The proposed technique is to store only mapping information in page units based on index blocks and manage them in block units. To this end, the proposed technique uses a sequential offset for storing and managing a plurality of mapping information in one page in a small block, and a reverse offset for a spare page corresponding to a change in mapping information in the block. Through this, the proposed technique has the advantage that the number of block-unit deletions is less than that of the existing technique, and the system memory usage required for mapping information management is low. Reduced by about 32%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.923-926
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• 2010

A sensor network system processes user queries using the recent field data collected by each sensor node. To process user queries, the system propagates the queries to the specific sensor nodes which have the relevant data and aggregates the results of the queries. However, if continuous queries are processed by the existing scheme, the system has the problem where the queries are propagated repeatedly. In this paper, we propose the query processing scheme to process the continuous queries over the sensor streaming data. To do this, each sensor node builds its own query index on its node. And, we present the scheme to deal with the unexpected data rising on the sensor node.

• Proceedings of the Korean Information Science Society Conference
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• 한국정보과학회 2001년도 봄 학술발표논문집 Vol.28 No.1 (B)
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• pp.64-66
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• 2001

비디오 데이터는 미디어의 특성상 시간의 흐름에 따라 객체의 위치가 변하는 움직임 객체(Moving Object)를 가지며, 움직임 객체를 기반으로 비디오 데이트를 색인 및 검색하기 위해서는 적합한 시공간 표현 기법이 요구된다. 따라서 본 논문에서는 비디오 데이터가 지니는 움직임 객체의 움직임 경로(Trajectory)를 효율적으로 모델링하고 사용자에게 빠른 검색 결과를 제공할수 있는 근사 탐색(Approximation Search)이 가능한 새로운 시공간 표현 기법을 제안한다. 이는 사용자가 직접 스케치한 움직임 경로를 토대로 검색을 수행하는 내용 기반 검색과 움직임 객체의 일련의 움직임 경로들과 움직임 경로가 일어나는 위치 정보를 통해 얻어진 개념(의미)을 이용한 개념 기반 검색을 지원한다.

• Proceedings of the Korea Contents Association Conference
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• 한국콘텐츠학회 2019년도 춘계종합학술대회
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• pp.451-452
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• 2019

논문 검색 서비스 응용에서는 공저자, 출판 정보 등을 표현하기 위해서 다양한 정점 레이블 (논문,저자) 및 간선 정보(주저자, 공저자)를 이용하여 그래프로 표현한다. 이와 함께 다양한 간선 특징 정보를 질의로 입력하는 연속 서브 그래프 매칭에 대한 요구가 존재한다. 본 논문에서는 간선의 다양한 특성을 지원하고 색인의 부하를 감소시킨 연속 서브 그래프 매칭 기법을 제안한다. 제안하는 기법은 거리 값과 질의 연관 정보만을 관리하여 간선의 다양한 특성을 지원하는 효율적인 서브 그래프 매칭을 수행한다.

• Journal of the Korean Society for information Management
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• 제30권3호
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• pp.23-48
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• 2013

This study compared and analyzed 15 CBMR (Content-based Music Retrieval) systems accessible on the web in terms of DB size and type, query type, access point, input and output type, and search functions, with reviewing features of music information and techniques used for transforming or transcribing of music sources, extracting and segmenting melodies, extracting and indexing features of music, and matching algorithms for CBMR systems. Application of text information retrieval techniques such as inverted indexing, N-gram indexing, Boolean search, truncation, keyword and phrase search, normalization, filtering, browsing, exact matching, similarity measure using edit distance, sorting, etc. to enhancing the CBMR; effort for increasing DB size and usability; and problems in extracting melodies, deleting stop notes in queries, and using solfege as pitch information were found as the results of analysis.

• The KIPS Transactions:PartD
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• 제13D권7호
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• pp.879-888
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• 2006

Recently many researchers have focused on management of Historical trajectories of moving objects in Euclidean spaces due to numerous sizes of accumulated data over time. However, the movement of moving objects in real applications generally has some constraints, for example vehicles on roads can only travel along connected road networks. In this paper, we propose an indexing method for trajectories of moving objects on road networks in order to process the network-based spatiotemporal range query. Our method contains the connect information of road networks to use the network distance for query processing, deals with trajectories which are represented by road segments in road networks, and manages them using multiple R-trees assigned per each road segment. Furthermore, it has a structure to be able to share R-tree among several road segments in large road networks. Consequently, we show that our method takes about 30% less in node accesses for the network-based spatiotemporal range query processing than other methods based on the Euclidean distance by experiments.

• Journal of the Korea Society of Computer and Information
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• 제10권4호
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• pp.65-75
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• 2005

Moving-objects databases should efficiently support database queries that refer to the trajectories and positions of continuously moving objects. To improve the performance of these queries. an efficient indexing scheme for continuously moving objects is required. To my knowledge, range queries on current positions cannot be handled by the 3D R-tree and the TB-tree. In order to handle range queries on current and past positions. I modified the original 3D R-tree to keep the now tags. Most of spatio-temporal index structures suffer from the fact that they cannot efficiently process range queries past positions of moving objects. To address this issue. we propose an access method, called the Tagged Adaptive 3DR-tree (or just TA3DR-tree), which is based on the original 3D R-tree method. The results of our extensive experiments show that the Tagged Adaptive 3DR-tree outperforms the original 3D R-tree and the TB-tree typically by a big margin.