• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.6
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• pp.1-17
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• 2001

Nowadays, spatiotemporal data models deal with objects which can be potentially useful for wide range applications in order to describe complex objects with spatial and/or temporal facilities. However, the information needed by each application usually varies, specially in the geographic information which depends on the kind of time oriented views, as defined in the modeling phase of the spatiotemporal geographic data design. To be able to deal with such diverse needs, geographic information systems must offer features that manipulate geometric, space-dependent(i.e, thematic), and spatial relationship positions with multiple time oriented views. This paper addresses problems of the formal definition of relationships among spatiotemporal objects and their properties on geographic information systems. The geographical data are divided in two main classes : geo-objects and geo-fields, which describe discrete and continuous representations of the spatial reality. I study semantics and syntax about the temporal changes of attributes and the relationship roles on geo-objects and non-geo-objects, This result will contribute on the design of object oriented spatiotemporal data model which is distinguishied from the recent geographic information system of the homogeneously anchored spatial objects

• Journal of KIISE:Databases
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• v.30 no.2
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• pp.176-183
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• 2003

Various techniques including histograms, sampling and parametric techniques have been proposed to estimate query result sizes for the query optimization. Histogram-based techniques are the most widely used form for the selectivity estimation in relational database systems. However, in the spatio-temporal databases for the moving objects, the continual changes of the data distribution suffer the direct utilization of the state of the art histogram techniques. Specifically for the future queries, we need another methodology that considers the updated information and keeps the accuracy of the result. In this paper we propose a novel approach based upon the duality and the marginal distribution to construct a histogram with very little time since the spatio-temporal histogram requires the data distribution defined by query predicates. We use data synopsis method in the dual space to construct spatio-temporal histograms. Our method is robust to changing data distributions during a certain period of time while the objects keep the linear movements. An additional feature of our approach supports the dynamic update incrementally and maintains the accuracy of the estimated result.

• Journal of Korea Spatial Information System Society
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• v.12 no.1
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• pp.28-36
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• 2010

Some context is characterized by a single event in computing environment, but many other contexts are determined by a lot of things which occur with a space and a time. The Realtime Sensor Network context-awareness service that interacts with the physical space can have property such as time. A methodology that is specified the relationship between the contexts and the service needs to be developed to Realtime context-awareness deal with spatio-temporal. In this paper, we propose an approach which should include spatio-temporal property in the context model, and verify its effectiveness using enhanced Petri-Net. The context-awareness service modeling of Realtime Sensor Network is discussed the properties of model such as basic Petri-Net, patterned Petri-Net, or Spatio-temporal Petri-Net. The proposed methodology demonstrated using an example that is SAEMANGUEM warming watching system. The use of Spatio-temporal Petri-Net will contribute not only to develop the application but also to model the spatio-temporal context awareness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1869-1876
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• 2006

Recently, STC techniques have been considered to be candidate to support multimedia services in the next generation mobile radio communications and have been developed the many communications systems in order to achieve the high data rates. In this paper, we Nose the Trellis-Coded Differential Space Time Modulation system with multiple symbol detection. The Trellis-code performs the set partition with unitary group codes. The Viterbi decoder containing new branch metrics is introduced in order to improve the bit error rate (BER) in the differential detection of the unitary differential space time modulation. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency.

• Journal of Korea Spatial Information System Society
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• v.9 no.1
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• pp.59-77
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• 2007

Advances in mobile techknowledges and supporting techniques require an effective representation and analysis of moving objects. Similarity search of moving object trajectories is an active research area in data mining. In this paper, we propose a trajectory search algorithm for spatio-temporal similarity of moving objects on road network. For this, we define spatio-temporal distance between two trajectories of moving objects on road networks, and propose a new method to measure spatio-temporal similarity based on the real road network distance. In addition, we propose a similar trajectory search algorithm that retrieves spatio-temporal similar trajectories in the road network. The algorithm uses a signature file in order to retrieve candidate trajectories efficiently. Finally, we provide performance analysis to show the efficiency of the proposed algorithm.

• Spatial Information Research
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• v.10 no.2
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• pp.185-199
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• 2002

The objective of this study is to investigate the suitable spatio-temporal analysis method considering the zoning effect of spatial analysis termed the modifiable areal unit problem(MAUP). In former studies of spatio-temporal analysis, there were disagreement between attribute data with spatial data, because of variation of administrative district aggregating attribute data. It is need to consider how the analysis zone effects spatial characteristics and spatio-temporal variation of urban region through land price variation analysis. This study considers MAUP through basic mesh system, which is composed of micro grid. Mesh system can solve disagreement of resolution between spatial data and attribute data.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.43-50
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• 2005

The Processing domains of spatio-temporal databases are divided into time-series databases for moving objects and sequence databases for discrete historical objects. Recently the selectivity estimation techniques for query optimization in spatio-temporal databases have been studied, but focused on query optimization in time-series databases. There wat no previous work on the selectivity estimation techniques for sequence databates as well. Therefore, we construct T-Minskew histogram for query optimization In sequence databases and propose a selectivity estimation method using the T-Minskew histogram. Furthermore we propose an effective histogram maintenance technique for food performance of the histogram.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.27-34
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• 2007

A mobile satellite broadcasting service including an ancillary terrestrial component (ATC) takes advantage of the satellite's inherent capability to provide broadcast service over global coverage. We consider the downlink transmission concept using ATC with space=time code (STC) for the mobile satellite communication. We do not regard ATC as simply a repeater but consider it as an antenna for STC. First transmission scenarios for an application of STC are represented. Next, we apply STC in the mobile satellite system including ATC and compare the system performance in the proposed architecture of ATC to that in the conventional structure. The simulation results are compared to the conventional downlink transmission concept for the mobile satellite broadcasting service.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.43-46
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• 2005

다차원 분석을 위한 OLAP 연산에서는 사용자의 요청에 빠르게 응답하기 위해 집계 값을 미리 계산하여 저장해 두는 사전 집계 방식을 이용한다. 시공간 데이터에 대한 사전 집계 기법으로는 R-트리의 각 노드에 대한 과거 집계 값을 요약 테이블로 관리하는 기법과 R-트리의 노드에서 현재 집계 값을 관리하는 기법이 있다. 그러나 이 기법들은 현재와 과거 모두의 집계 정보를 필요로 하는 시스템에서는 성능이 저하되며, 특히 과거 집계 정보의 경우 시간에 따른 계층화가 되어있지 않아 시간에 대한 계층 분석에 어려움이 있다. 본 논문에서는 시공간 데이터의 현재와 과거 집계 정보를 효율적으로 관리하는 기법을 제안한다. 제안 기법은 aR-tree를 이용하여 해당 영역에 대한 현재 집계 정보를 저장하고, 각 노드에 과거 집계 정보에 대한 연결을 위하여 링크를 추가하였다. 과거 집계 정보는 각 노드의 과거에서 현재까지의 집계 정보를 계층 구조로 유지하는 시간 요약 집계 테이블을 만들어 저장한다. 따라서 제안한 기법은 현재와 과거 집계 정보를 모두 유지할 수 있으므로 현재와 과거 집계 정보에 대한 처리 성능을 향상시킨다. 또한 제안 기법에서는 공간 정보를 공간 인덱스인 R-트리로 유지하고, 과거로부터의 시간 정보를 시간 요약 집계 테이블을 이용하여 계층화시켜 유지하므로 시간과 공간에 대한 계층 분석이 용이하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.773-776
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• 2020

웹 뉴스 기사는 태풍과 같은 재해 발생상황에 대한 신속하고 정확한 정보를 포함하고 있다. 예를 들어, 태풍의 발생시점, 이동·예측경로, 피해·사고 현황 등 유용한 정보를 텍스트, 이미지, 동영상의 형태로 관련 상황정보를 전달한다. 그러나 대부분의 재해재난 관련 뉴스 기사는 특정 시점의 정보만을 웹페이지 형태로 제공하므로, 시계열 측면의 연결성을 지니는 기사들에 대한 정보를 전달하기 어렵다. 또한 시간적 변화에 따라 기사 내용에 포함된 장소, 지역, 건물 등의 지명에 대한 공간적 정보를 지도와 연계하여 정보를 전달하는데 한계가 있어, 시공간적 변화에 따른 특정 재해재난 상황정보에 대한 전체적인 현황파악이 어렵다. 따라서, 본 논문에서는 데이터 시각화 측면에서 이러한 한계를 극복하기 위해, 1) 웹크롤링을 통해 구축된 뉴스 빅데이터를 자연어 처리를 통해 태풍과 관련된 뉴스 기사들을 추출하였고, 2) 시공간적 관련 정보를 지식그래프로 구축하였고, 이를 통해 최근 발생한 태풍 사건들과 관련된 뉴스 정보를 시계열 특성을 고려하여 3) 인터렉티브 지도 기반의 태풍 상황정보를 시각화하는 방안을 연구하였다.