• Journal of Korea Spatial Information System Society
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• v.6 no.2 s.12
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• pp.39-49
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• 2004

An increasing number of distributed applications will be achieved with mobile technology. These applications face temporary loss of network connectivity when they move. They need to discover other hosts in an ad-hoc manner, and they are likely to have scarce resources including CPU speed, memory and battery power. Software engineers building mobile applications need to use a suitable middleware that resolves these problems and offers appropriate support for developing mobile applications. In this paper, we describe the meta-server building for middleware that addresses reflective context awareness and present usability with demonstration. Metadata is consist of user configuration, device configuration, user context, device context and dynamic image metadata. When middleware send a saving or retrieval request to meta-server, it returns messages to middleware after the verification of the request. This meta-server has the application for multimedia stream services with context awareness.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.3
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• pp.319-328
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• 2000

The Message-Passing Interface(MPI) is a standard interface for parallel programming environment, based on that application programs run on the processors of a parallel computer. Processor nodes execute processes consisting the program by passing messages to one another. During executing, however, if a fault occurs on a processor node or a process, this will result an inconsistent state, and consequently, the whole program will have to be stopped. To solve this problem, in this paper, we propose a fault-tolerant message passing interface(FT-MPI) by adding a fault manager module to MPI. The proposed FT-MPI does not need any hardware support, and each application program based on MPI can run on the FT-MPI without any modification. The proposed fault tolerance scheme uses the so-called hot-spare process duplication method, and verified by simulations that application programs run despite of any fault with less than 5% overhead on execution time.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.219-230
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• 2002

One of the most important functions digital libraries need to offer is to help users find necessary information in a distributed environment in the most efficient and effective manner. In order to meet the goal, it is desirable to link scattered pieces of information and present them as a logically coherent whole when the user wants it, so that he or she doesn't need to know their physical location. The virtual document is an integrated document that the total or part of the physical documents stored in a specific repository are linked dynamically. Our MIRAGE-III digital library system provides a content-based retrieval of physical documents and the virtual documents in XML. This system provides a retrieval of partial documents, attributes and hierarchical structures and linked-documents based in structured documents like XML or SGML. In this paper we describe a methodology of design and implementation of the query processor and retrieval server in the MIRAGE-III digital library system.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1441-1456
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• 1998

The concept of a hyperpresmtation, as an extension of a hypermedia, is the presentation in which time-varying multimedia presentations are dynamically linked together and a hyperlink's context can be changed over time at any time during a continuous presentation. Problems caused by integrating the hyperpresentation into an existing multimedia system which handles a sequential presentation only are, how to describe the hyperprcsentation, how to set up a hyperlink on a continuous media, and how to check the consistency of the synchronized presentations. In this paper. a new synchronization description method for the hyperpresentation and a method for setting a hyper link on a continuous media during" presentation are proposed after havin!; SHrvey of existing methods, The proposed method deals with only the DC value in a stream ut a DCT based compressed data for checking a condition of te link. Finally, the method for checking the consistency of mixed presentations before actual play of the hnlerpresentation is described. Proposed methods are implemented on MuX(Multimedia IO Server) where a sample scenario is tested.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.813-817
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• 2008

Intelligent Robots (IR) get data of the current situation from sensors and perform knowledgeable services. Self-reconfiguration of IR is an important factor to change itself without stopping while supporting environment and technology change. In this paper, we propose an agent based self-reconfiguration framework of IR using ESB (Enterprise Service Bus). This framework focuses on dynamic discovery and reconfiguration of service-oriented applications using multi-agent system in intelligent robots. When IR meets an irresolvable situation it downloads a necessary service agent from an external service repository, executes the agent, and resolves the situation. Agent technology provides an intelligent approach for collaborations of IR. The prototype has also been implemented to show the validity of our study.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.19-30
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• 2012

Based on the internet-based infrastructures such as various information devices, social network systems and cloud computing environments, distributed and sharable data are growing explosively. Recently, as a data analysis and mining technique for extracting, analyzing and classifying the inherent and useful knowledge and information, Formal Concept Analysis on binary or many-valued data has been successfully applied in many diverse fields. However, in formal concept analysis, there has been little research conducted on analyzing interval data whose attributes have some interval values. In this paper, we propose a new approach for classification of interval data based on the formal concept analysis. We present the development of a supporting tool(iFCA) that provides the proposed approach for the binarization of interval data table, concept extraction and construction of concept hierarchies. Finally, with some experiments over real-world data sets, we demonstrate that our approach provides some useful and effective ways for analyzing and mining interval data.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.31-38
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• 2004

In mobile agent environments, migration of an agent occurs continuously due to the mobility of agents. So cascaded delegation can occur among places for delegating the privilege to execute the agent. Because the existing delegation scheme considers only the delegation between two places that participate in migration of an agent, it does not support secure cascaded delegation. In this paper, we propose a cascaded delegation scheme that provides agents with secure cascaded delegation in mobile agent environments. Depending on the trust-relationship among places, the proposed scheme achieves the goal by nesting each delegation token or by nesting only initial token signed by creator of the agent within the signed part of the next immediate delegation token. And we prove that the proposed scheme is secure against the attack of replaying a message and the attack of substituting a delegation token.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.610-622
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• 2003

Metadata Registry was developed to dynamically manage metadata and to increase interoperability between various and heterogeneous metadata. The built metadata registry can be used as a standard guideline for creation of new databases and it provides a radical data integration mechanism. However, in the situation that an enormous databases must be integrated progressively, there is a limit to the existing metadata-based approach. In case that each database has no statistical information for its use rate and the restricted cost is given to us for a unit time, existing metadata-based approaches do not provide how to select some databases to be preferentially integrated and to build a metadata registry progressively, In this paper, we propose a methodology that can create progressively metadata registries in the case. The proposed methodology is based on data visibility and hierarchical metadata registry. We also describe the system that have been developed for applying the methodology to a real domain, and then described its results.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.177-182
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• 2017

As major ICT technologies such as IoT, cloud computing, and Big Data are being applied to manufacturing, smart factories are beginning to be built. The key of smart factory implementation is the ability to acquire and analyze data of the factory. Therefore, the need for a big data analysis platform is increasing. The purpose of this study is to construct a platform for big data analysis of manufacturing process and propose integrated method for analysis. The proposed platform is a RHadoop-based structure that integrates analysis tool R and Hadoop to distribute a large amount of datasets. It can store and analyze big data collected in the unit process and factory in the automation system directly in HBase, and it has overcome the limitations of RDB - based analysis. Such a platform should be developed in consideration of the unit process suitability for smart factories, and it is expected to be a guide to building IoT platforms for SMEs that intend to introduce smart factories into the manufacturing process.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.1-10
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• 2014

In this paper, we propose a real-time video playback scheme for the N-Screen service based on Windows Azure. This scheme creates several playback blocks based on the performance of each node by non-uniform splitting of the original video. To reduce transcoding-time, it allocates the playback blocks to a corresponding node by transcoding the playback blocks. Through the simulation, we show that it is more effective to use real-time video playback for the N-screen service than the previous method. The proposed scheme splits an AVI format 300MB source video with non-uniform playback blocks. It allocates the playback blocks to the heterogeneous node of Windows Azure, the commercial cloud system and measures of transcoding-time by transcoding non-uniform playback blocks to mp4 and Flv format. As a result, the proposed scheme improves the performance of the N-screen service based on Windows Azure compared to the previous uniform split strategy.