• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.1-12
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• 2003

Recently, many researches into distributed processing on Internet, and multimedia data processing have been performed. Rapid and convenient multimedia services supplied with high quality and high speed are to be needed. In this paper, we design and implement clip-based video retrieval system on the Web enviroment in real-time. Our system consists of the content-based indexing system supporting convenient services for video content providers, and the Web-based retrieval system in order to make it easy and various information retrieval for users in the Web. Three important methods are used in the content-based indexing system, key frame extracting method by dividing video data, clip file creation method by clustering related information, and video database construction method by using clip unit. In Web-based retrieval system, retrieval method ny using a key word, two dimension browsing method of key frame, and real-time display method of the clip are used. In this paper, we design and implement the system that supports real-time display method of the clip are used. In this paper, we design and implement the system that supports real-time retrieval for video clips on Web environment and provides the multimedia service in stability. The proposed methods show a usefulness of video content providing, and provide an easy method for serching intented video content.

• Journal of KIISE:Databases
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• v.37 no.6
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• pp.324-332
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• 2010

The majority of event detection in real-time embedded sensor network systems is based on data fusion that uses noisy sensor data collected from complicated real-world environments. Current research has produced several excellent low-level mechanisms to collect sensor data and perform aggregation. However, solutions that enable these systems to provide real-time data processing using readings from heterogeneous sensors and subsequently detect complex events of interest in real-time fashion need further research. We are developing real-time event detection approaches which allow light-weight data fusion and do not require significant computing resources. Underlying the event detection framework is a collection of real-time monitoring and fusion mechanisms that are invoked upon the arrival of sensor data. The combination of these mechanisms and the framework has the potential to significantly improve the timeliness and reduce the resource requirements of embedded sensor networks. In addition to that, we discuss about a privacy that is foundation technique for trusted embedded sensor network system and explain anonymization technique to ensure privacy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.131-140
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• 1992

For a real-time flood forecasting and reservoir control problem of a multipurpose dam, the online acquisition of hydro-meteorological data and computerized analysis of the acquired data are absolutely necessary for the prompt decision of reservoir discharges which can minimize the possible damages and simultaneously maximize the utilization of the runoff. By introducing a man-machine interface such as condensed color graphics of the analyzed results, it is much easier and faster to transform the information to the decision maker who can decide the reservoir discharge. The newly developed PC-REFCON, which represents the PC based real-time flood forecasting and reservoir control, can easily handle the above problems by adopting a innovative decision support system. The system has three principal components of, a data base subsystem which acquires and manages real-time data, a model subsystem which forecasts the flood runoff and simulates the reservoir operation, and a dialogue subsystem which helps decision maker and system engineers using various graphics and tables with renovative methodologies. The developed PC-REFCON will be utilized from the coming Summer of 1992 for the flood control of all the nine multipurpose reservoirs in Korea.

• Journal of KIISE:Databases
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• v.34 no.6
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• pp.483-492
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• 2007

Time series of conventional prediction techniques uses the model which is generated from the training step. This model is applied to new input data without any change. If this model is applied directly to stream data, the rate of prediction accuracy will be decreased. This paper proposes an stream data prediction technique using sliding window and regression. This technique considers the characteristic of time series which may be changed over time. It is composed of two steps. The first step executes a fractional process for applying input data to the regression model. The second step updates the model by using its information as new data. Additionally, the model is maintained by only recent data in a queue. This approach has the following two advantages. It maintains the minimum information of the model by using a matrix, so space complexity is reduced. Moreover, it prevents the increment of error rate by updating the model over time. Accuracy rate of the proposed method is measured by RME(Relative Mean Error) and RMSE(Root Mean Square Error). The results of stream data prediction experiment are performed by the proposed technique IMQR(Incremental Multiple Quadratic Regression) is more efficient than those of MLR(Multiple Linear Regression) and SVR(Support Vector Regression).

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.286-292
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• 1995

국내 최초의 한국표준원전 가압경수로인 울진 3,4 호기의 운전 특성을 정확하게 실시간으로 모사할 수 있는 한국표준원전 NPA가 개발되고 있다. 동 NPA는 발전소의 정상 및 비정상 운전 상태를 Desk-top 소령 컴퓨터에서 모사하여 그 결과를 그림화면(mimic)에 나타내고 운전원 조치 사항을 Interactive하게 수용할 수 있는 능력을 갖추고 있다. 한국표준원전 NPA의 개발을 위하여 울진 3,4 호기 한국표준원전의 설계 자료를 기준으로 그래픽사용자 인터레이스의 새로운 mimic 및 해석모델에서 사용하는 데이타베이스를 성공적으로 작성하였다. 향후 한국표준원전 NPA는 새로운 모형 개발을 완료한 후 발전소 운전자료와의 비교분석을 통해 성능 검증을 거치면 교육을 및 엔지니어링 작업에 유용하게 사용될 수 있을 것이다.

• The Journal of Information Technology and Database
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• v.8 no.2
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• pp.103-114
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• 2001

In this paper, we propose an efficient index mechanism for real-time main memory database systems. Existing main memory index structures based on the tree can effectively support range searches. However, it doesn't guarantee the real-time characteristic because difference between the access time of a node and an average access time can be high. The index structures based on the hash have always a regular random access time on the simple searches and that speed is very fast. However they do not support range searches. To solve such problems, we propose a new index mechanism called Hyper Tree-Hash (Hyper-TH) that combines ECBH (Extendible Chained Bucket Hashing) and T＊-tree. ECBH can be dynamically extended and has a very fast access time. T＊-tree effectively supports the range searches. We show through our experiments that the proposed mechanism outperforms existing other index structures.

• Journal of KIISE:Databases
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• v.35 no.6
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• pp.459-468
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• 2008

A data stream which is a massive unbounded sequence of data elements continuously generated at a rapid rate. Many recent research activities for emerging applications often need to deal with the data stream. Such applications can be web click monitoring, sensor data processing, network traffic analysis. telephone records and multi-media data. For this. data processing over a data stream are not performed on the stored data but performed the newly updated data with pre-registered queries, and then return a result immediately or periodically. Recently, many studies are focused on dealing with a data stream more than a stored data set. Especially. there are many researches to optimize continuous queries in order to perform them efficiently. This paper proposes a query optimization algorithm to manage continuous query which has multiple join operators(Multi-way join) over data streams. It is called by an Extended Greedy query optimization based on a greedy algorithm. It defines a join cost by a required operation to compute a join and an operation to process a result and then stores all information for computing join cost and join cost in the statistics catalog. To overcome a weak point of greedy algorithm which has poor performance, the algorithm selects the set of operators with a small lay, instead of operator with the smallest cost. The set is influenced the accuracy and execution time of the algorithm and can be controlled adaptively by two user-defined values. Experiment results illustrate the performance of the EGA algorithm in various stream environments.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.578-589
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• 2006

Owing to the proliferation of Radio Frequency Identification (RFID) technologies which is being watched as a core technology of ubiquitous computing, applications which offer convenience to people using RFID technologies are more and more increased. To easily develop these applications, a middleware system which acts as a bridge between RFID hardware and application is essential. In this paper, we propose a novel XML-based RFID middleware system called UbiCore (Ubiquitous Core). UbiCore has following features: First, UbiCore employs its own query language called XQueryStream (XQuery for Stream Data) which is originated from XQuery. Second, UbiCore has the preprocessing phase called pre-filtering prior to query evaluation and reuses the intermediate result of previous evaluation to speed up the processing of RFID tag data stream. Third, UbiCore supports query on both continuously generated stream data and archived historical data. And last, UbiCore offers a distinct markup language called Context-driven Service Markup Language (CSML) to easily specify the linking information between context and service.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.138-149
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• 2006

As the environment with sensor network and ubiquitous computing is emerged, there are many demands of handling continuous, fast data such as streaming data. As work about streaming data has begun, work about management of streaming data in Publish-Subscribe system is started. The recent emergence of XML as a standard for information exchange on Internet has led to more interest in Publish - Subscribe system. A filtering technique of streaming XML data in the existing Publish- Subscribe system is using some schemes based on automata and YFilter, which is one of filtering techniques, is very popular. YFilter exploits commonality among path queries by sharing the common prefixes of the paths so that they are processed at most one and that is using the top-down approach. However, because partial matching path queries interrupt the common prefix sharing and don't calculate from root, throughput of YFilter decreases. So we use sharing of commonality among path queries with the common postfixes of the paths and use the bottom-up approach instead of the top-down approach. This filtering technique is called as PoSFilter. And we verify this technique through comparing with YFilter about throughput.

• The Journal of Information Technology and Database
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• v.1 no.2
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• pp.37-52
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• 1994

오늘날의 정보시스템 구축 방향은 대형 컴퓨터를 중심으로 수많은 단말기를 연결한 수직형네트워크 시스템에서 다운사이징과 네트워크 기술이 결합하여 분산적으로 자료를 처리하는 클라이언트/서버 시스템 구축으로 변화하고 있다. 본 연구는 모든 단말기를 통제하는 대형 컴퓨터를 운영하는 전산망에서 클라이언트/서버 전산망으로 전환하는 하나의 사례연구를 통하여 구축환경변화, 시스템구성, 경영환경변화를 분석함으로써 클라이언트/서버 시스템의 성공적인 사례를 제시하는 것이다. 클라이언트/서버 시스템으로 변환하기전에 재개발할 시스템의 목표와 방향을 설정하기 위해서 벤치마킹을 실시하였고, 이의 결과를 바탕으로 경영업무의 프로세스를 재설계 하였다. 그리고 기업의 내부와 외부자료에 관한 표준화를 실시하였다. 정보기술 투자의 경제성과 경쟁우위 확보를 위하여 클라이언트/서버 시스템을 구현하게 되었으며 판매물류, 생산물류, 그리고 재무회계에 관한 경영지원시스템으로 구성되는 종합물류시스템 이외에 영업소에 관련된 영업정보시스템과 자동창고시스템이 컴퓨터 네트워크와 관련해서 시스템을 구성하였다. 구성 전략 촛점은 리엔지니어링, 다운사이징, 그리고 벤치마킹이었다. 시스템을 재개발한 후 업무의 계획, 진행, 분석, 감리등에 관한 체계적 업무흐름이 정착될 정도로 변화하였으며, 통신방식의 확대 및 다양화로 의사소통의 원활화와 타 관련업무와 연계처리, 그리고 부서들 상호간에 정보를 공유할 수 있었다. 또한 정보기술에 의한 업무처리를 기본으로 하는 기능적 태도로 인하여 관리자와 실무자의 업무운영에 관한 사고와 의식이 변화하였다. 따라서 매출액의 증가와 종업원수가 감소되었다.