• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.143-150
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• 2013

The purpose of this study is to suggest the methodology to develop variable-scale network model, which is able to induce large-scale road network in detailed level corresponding to small-scale linear objects with various abstraction in higher level. For this purpose, the definition of terms, the benefits and the specific procedures related with a variable-scale model were examined. Second, representation level and the components of layer to design the variable-scale map were presented. In addition, rule-based data generating method and indexing structure for higher LoD were defined. Finally, the implementation and verification of the model were performed to road network in study area (Jeju -do) so that the proposed algorithm can be practical. That is, generated variable scale road network were saved and managed in spatial database (Oracle Spatial) and performance analysis were carried out for the effectiveness and feasibility of the model.

• Journal of Korea Spatial Information System Society
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• v.8 no.2 s.17
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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.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.2 s.308
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• pp.1-11
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• 2006

In this paper, we propose the novel video retrieval algorithm using non-parametric based motion classification in the shot-based video indexing structure. The proposed system firstly gets the key frame and motion information from each shot segmented by scene change detection method, and then extracts visual features and non-parametric based motion information from them. Finally, we construct real-time retrieval system supporting similarity comparison of these spatio-temporal features. After the normalized motion vector fields is created from MPEG compressed stream, the extraction of non-parametric based motion feature is effectively achieved by discretizing each normalized motion vectors into various angle bins, and considering a mean, a variance, and a direction of these bins. We use the edge-based spatial descriptor to extract the visual feature in key frames. Experimental evidence shows that our algorithm outperforms other video retrieval methods for image indexing and retrieval. To index the feature vectors, we use R*-tree structures.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.835-844
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• 2004

Recently, the location-based service for moving customers is becoming one of the most important service in mobile communication area. For moving object applications, there are lots of update operations and such update loads are concentrated on some particular area unevenly. Range queries, whose range can be window or circular, are the most essential query types in LBS. We need to distinguish completely contained cells from partially contained cells in those range queries. Also, it is necessary to consider temporal dimension to filter out qualifying objects correctly. In this paper, we adopt two-level index structures with fixed grid file structures in the second level, which are designed to minimize update operations. We propose a spatial ceil filtering method using VP filtering and a combined spatio-temporal filtering method using time gone concepts. Some experimental results are shown for various window queries and circular queries with different filtering combinations to show the performance tradeoffs of the proposed methods.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.23-32
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• 2011

In this paper, we develop a method for generating thumbnail images at hybrid domain combined the spatial domain and transform domain. The proposed method generates a pixel of a thumbnail image by adding a DC value of residual transform coefficients and an average value of an estimate block. For effectively calculating average values of estimate blocks, we propose a method for reconstructing the boundary pixels of a block. In comparison to the conventional method of decoding the bit stream then scaling down the decoded images, the developed method reduces the complexity by more than 60% while producing identical thumbnail images.

• International Journal of Contents
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• v.11 no.1
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• pp.69-72
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• 2015

Generally, existing parallel main-memory spatial index structures to avoid the trade-off between query freshness and CPU cost uses light-weight locking techniques. However, still, the lock based methods have some limits such as thrashing which is a well-known problem in lock based methods. In this paper, we propose a distributed index structure for moving objects exploiting the parallelism in multiple machines. The proposed index is a lock free multi-version concurrency technique based on the D-Stream model of Spark Stream. The proposed method exploits the multiversion nature of D-Stream of Spark Streaming.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.31-33
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• 2001

고비용의 공간 연산을 수행해야 하는 공간 질의 처리는 여과-정제의 2단계 처리가 일반적이다. 그러나, 2단계 색인 방법은 여과율이 좋지 못한 단점이 있으므로, 최근 다단계 여과 과정이 많이 연구되고 있다. 다단계 여과 과정은 1차 여과된 객체에 대하여 더욱 정밀한 필터를 적용함으로써 후부 객체 수를 줄이는 방법으로 접근하고 있으나, 여러 번의 여과 단계를 거치므로 수행 시간이 길어지고 추가 정보유지로 인한 저장 공간 낭비 등의 단점이 있다. 본 논문에서는 전체 공간 영역을 격자로 분할하고, 객체를 격자 위에 구성하는 2단계의 공간 색인 방법을 제안한다. 제안된 색인 방법은 Dead Space의 크기를 줄이고, 한 번의 여과 과정으로 높은 여과율을 갖는다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.341-346
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• 2004

본 연구에서는 사례기반추론(case-based reasoning)을 기본으로 하여 실무자의 분류 기법 또는 분류 구조 결정을 돕는 의사 결정 지원 시스템의 모델을 제시한다. 주요한 네 가지 고려 항목은 자료종류(dataset), 위치(location), 기후(climate), 그리고 분류항목(class)이며 사용자는 이들 네 항목에 대해 적합한 값을 선택하게 된다. 본 시스템은 색인화(indexing) 규칙에 따라 관계형 데이터베이스에 저장된 사례들을 추출하여 제시하며 사용자는 그 중 가장 높은 일치도를 보인 사례들을 참고할 수 있다. 본 연구에서는 위계구조를 통해 다양한 분류 조건을 스크린 상에서 선택할 수 있게 함으로써 사용자가 이에 내재된 논리를 분류 구조의 설계에 반영할 수 있게 한다. 또한 Statistics 기능을 통해 여러 사례의 항목당 분포를 사용자가 검토할 수 있게 함으로써 가장 적합한 사례를 의사결정 지원 시스템과의 피드백을 통해 찾아낼 수 있게 해준다. 이밖에 분류 조건을 변화 시켜가면서 상황의 변화를 참고할 수 있도록 Navigation 기능을 고안하였다.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.426-439
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• 2012

The goal of this study is to propose a new method to capture the qualitative person spatial behavior. Beyond tracking or indexing the change of the location of a person, the changes in the relationships between a person and its environment are considered as the main source for the formal model of this study. Specifically, this paper focuses on the movement behavior of a person near the boundary of a region. To capture the behavior of person near the boundary of regions, a new formal approach for integrating an object's scope of influence is described. Such an object, a spatio-temporally extended point (STEP), is considered here by addressing its scope of influence as potential events or interactions area in conjunction with its location. The formalism presented is based on a topological data model and introduces a 12-intersection model to represent the topological relations between a region and the STEP in 2-dimensional space. From the perspective of STEP concept, a prototype analysis results are provided by using GPS tracking data in real world.

• Journal of KIISE:Software and Applications
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• v.26 no.9
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• pp.1039-1051
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• 1999

시공간 데이타베이스는 현실세계의 객체에 대하여 효율적인 공간 관리와 이력 관리를 지원한다. 이러한 시공간 데이타베이스는 시간차원과 공간차원이라는 이질적 데이타 공간을 관리하여야 하는 대단히 복잡한 시스템이다. 따라서 데이타에 대한 효율적 접근 방법에 대한 연구가 필수적이며, 이는 효율적 색인 기법의 개발을 통하여 이룰 수 있다. 그러나 시공간 데이타에 대한 접근방법 연구는 거의 이루어지지 않고 있으며 극소수의 사례들마저도 공간 객체의 이력 개념을 지원하는 것이 아니라 멀티미디어 객체의 상대적 시간만을 지원하고 있다. 따라서 이 논문에서는 공간 데이타의 이력을 표현하는 시공간 데이타에 대하여 효율적으로 색인하기 위한 방안으로서 시간과 공간을 단일화된 색인 영역으로 통합하는 단일화된 시공간 색인 모델을 제시하고, 이를 기존의 R-트리를 기반으로 확장한 색인을 설계 및 구현하였으며, 아울러 다양한 유형의 시공간 연산에 대한 색인의 성능을 평가하였다.Abstract Spatiotemporal databases are able to support an efficient spatial management as well as historical management for an object in the real world. It is very complex to manage these two dimensions why there exists on difference of inborn property of temporal and spatial dimensions. Therefore an efficient access method should be studied, and it can be done by means of development of efficient indexing technology.However, there is a few related work in the research of access methods of spatiotemporal data. Also the previous works do not support the concept of history for spatial object, and only support the relative time among multimedia objects. Therefore, in this paper, we propose a unified Spatiotemporal index model as an efficient index for Spatiotemporal data. And we not only design Spatiotemporal index that has been extended to historical management facility on the basis of conventional R-tree, but also implement it. Finally we have evaluated performance of index for the various kinds of Spatiotemporal operations.