• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.21-31
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• 2012

Recently, according to the development of ubiquitous computing technology, the efficient management of locations of moving objects is increasing rapidly in various fields. However, MODBMS and DSMS can not support the efficient real-time management of spatio-temporal stream data of moving objects. Therefore, this paper designed and implemented a spatio-temporal DSMS which can support the efficient real-time management of spatio-temporal stream data of moving objects. Especially, to develop the spatio-temporal DSMS, we extended STREAM of Stanford University and used GEOS that supports spatial data types and spatial operators of OGC. Finally, this paper proved the efficiency of the spatio-temporal DSMS by applying it to the real-time monitoring field which requires the real-time management of spatio-temporal stream data of moving objects.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.217-223
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• 2022

Subspace clustering for online data streams requires a large amount of memory resources as all subsets of data dimensions must be examined. In order to track the continuous change of clusters for a data stream in a finite memory space, in this paper, we propose a grid-based subspace clustering algorithm that effectively uses memory resources. Given an n-dimensional data stream, the distribution information of data items in data space is monitored by a grid-cell list. When the frequency of data items in the grid-cell list of the first level is high and it becomes a unit grid-cell, the grid-cell list of the next level is created as a child node in order to find clusters of all possible subspaces from the grid-cell. In this way, a maximum n-level grid-cell subspace tree is constructed, and a k-dimensional subspace cluster can be found at the k^th level of the subspace grid-cell tree. Through experiments, it was confirmed that the proposed method uses computing resources more efficiently by expanding only the dense space while maintaining the same accuracy as the existing method.

• Journal of Digital Contents Society
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• v.13 no.1
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• pp.21-29
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• 2012

In ubiquitous computing environment, rising large scale data exchange through sensor network with sharply growing the internet, the processing of the continuous stream data is required. Therefore there are some mining researches related to the extracting of frequent structures and the efficient query processing of XML stream data. In this paper, we propose a mining method to extract frequent structures of XML stream data in recent window based on the active window sliding using trigger rule. The proposed method is a basic research to control the stream data flow for data mining and continuous query by trigger rules.

• Journal of Korea Spatial Information System Society
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• v.9 no.1
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• pp.91-104
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• 2007

In ubiquitous computing environment, people expect services to change actively in response to the change of themselves and surrounding environment. In order to meet such expectations, the streaming service needs technologies for migrating through various devices, following the user's movement, and the technology of individualized streaming push service. In this paper, we designed and implemented U-Stream, a ubiquitous streaming service system, based on user-defined context and stream view. The system classifies contexts according to streaming service migration and allows users to define some contexts and, by doing so, provides user-oriented individualized services rather than uniform services based solely on the developers' anticipations.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.619-627
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• 1999

To support multimedia services between network domains with different environments, it is required to map the functionalities in many aspects. In this paper, we implemented interworking gateway which provides protocol conversion and QoS(Quality of Service) adaptation to interwork DAVIC services based on ATM(Asynchronous TRansfer Model )network and Internet AV services. The interworking gateway converts RTSP(Real-Time Streaming Protocol ) message into DSM-CC(Digital Storage Media Command & Control) messages to control the stream that is served in ATM network, and transmits data stream by using RTP(Real-Time Transport Protocol) The interworking gateway provides QoS adaptation functionalities by QoS monitoring and MPEG filtering to meet the variation of network bandwidth.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.117-128
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• 2006

In this paper, we propose a streaming method for XML data that supports energy-efficient processing of queries over the stream in mobile clients. We propose new stream organizations for XML data which have different kinds of addresses to related data in a stream. We describe event-driven stream generation algorithms for the proposed stream structures and provide search algorithms for simple XML path queries which leverage the access mechanisms incorporated in the stream. Experimental results show that our approaches can effectively improve the tuning time performance of user queries in a wireless broadcasting environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.97-100
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• 2005

최근 유비쿼터스 컴퓨팅 및 인터넷 서비스에 대한 관심이 증대되면서, 대용량의 데이터에 내재되어 있는 정보를 빠른 시간 내에 처리하여 새로운 지식을 창출하려는 요구가 증가하고 있다. 데이터 마이닝 기법을 이용하여 데이터 스트림에서 빈발항목을 탐색하는 기존의 연구는 시간을 고려하지 않고 단순히 집계를 통하여 빈발항목을 탐색하기 때문에 정확성을 보장하지 못한다. 따라서 본 논문에서는 데이터 스트림에서 시간적 측면을 고려하여 상대적인 빈발항목을 탐색하기 위한 새로운 알고리즘을 제안하고자 한다. 논문에서 제안하는 알고리즘의 성능은 다양한 실험을 통해서 검증된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.789-792
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• 2011

RFID(Radio Frequency Identification) 시스템은 비접촉식 무선 인식 기술로 유통 및 물류, 환경, 교통, 보안 분야 등 산업 전반에 걸쳐 다양하게 활용되고 있다. 그러나 태그의 정보가 전송과정에서 무선특성에 따른 과도한 정보 노출과 사용자의 위치정보 추적 등 심각한 프라이버시 침해를 유발시킨다. 본 논문에서는 해쉬된 ID 와 스트림 암호 알고리즘을 이용한 OTP 를 활용하여 리더와 태그간 상호인증을 제공하는 프로토콜을 제안한다. 제안된 프로토콜의 OTP 생성에 사용된 NLM-128 알고리즘은 $2^{128}$ 비도 수준(Security level)을 갖는 스트림 암호로써, 안전성 및 구현 용이성 등의 특징을 가지며 RFID/USN 등의 저전력, 제한된 메모리 및 컴퓨팅 사양에서 적용하기 용이한 알고리즘이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.211-212
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• 2011

스트림 프로세싱 시스템은 실시간 데이터 수집 장치와 대규모 분산 컴퓨팅 환경이 결합되어 데이터 생성과 가공을 통하여 다수의 결과를 병렬적으로 도출하는 분산 프로그래밍 모델이다. 본 논문에서는 프로세스간에 필수적으로 요구되는 유입데이터 버퍼 관리에 초점을 두고 있다. 데이터의 유입률에 따라 동적으로 분석 프로세스를 확장시킴으로서 프로세스간 버퍼의 크기를 제어하는 기법을 제안하며 시뮬레이션을 통하여 성능 분석을 하였다.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.43-54
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• 2009

As R&D(Research and Development) is going on actively to develop technologies for the ubiquitous computing environment, which Is the human-oriented future computing environment, GIS dealing with spatio-temporal data is emerging as a promising technology. This also increases the necessity of the middleware for providing services to give interoperability in various heterogeneous environments. The core technologies of the middleware are real-time processing technology of data streams coming unceasingly from positioning systems and data stream processing technology developed for non-spatio-temporal data. However, it has problems in processing queries on spatio-temporal data efficiently. Accordingly, this paper designed and implemented the spatio-temporal middleware that provides interoperability between a mobile spatio-temporal DBMS(DataBase Management System) and a server spatio-temporal MMDBMS(Main Memory DataBase Management System). The spatio-temporal middleware maintains interoperability among heterogeneous devices and guarantees data integrity in query processing through real-time processing of unceasing spatio-temporal data streams and two way synchronization of spatio-temporal DBMSs. In addition, it manages session for the connection of each spatio-temporal DBMS and manages resources for its stable operation. Finally, this paper proved the usability of the spatio-temporal middleware by applying it to a real-time position tracking system.