• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.387-398
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• 2003

Materialized views have received much attention for query performance improvement. They need to be refreshed whenever their underlying data sources are updated. They could be recomputed from scratch or they could be incrementally refreshed by reflecting only those portions of updates that affect them. With emergence of XML as the standard for data exchange on the Web, active research is under way on effectively storing and retrieving XML documents. In this paper, we describe a performance study on the incremental refresh of XML materialized views for the case where XML documents are stored in a relational DBMS, and XML materialized views are maintained with incremental refresh. We describe implementation of a prototype XML storage system that supports XML materialized views and their incremental refresh, and report the performance results obtained with the implemented system through a detailed set of experiments on the incremental refresh of XML materialized views. The results show that the XML view maintenance with incremental refresh outperforms the ordinary view recomputation.

• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.786-791
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• 2015

The environment of Internet of Things (IoT) wherein various devices are connected through the Internet with value-added network functions, is currently a subject of active study. Accordingly, the existing computing environment based on desktop or mobile systems is being expanded into a computing environment of more diverse devices. Because the response of program launching is important in terms of User Experience (UX) in IoT environments, the technology for guaranteeing rapid response of program launching in IoT devices is getting the focus of much current research. In this paper we analyze the Zygote technique, which is being used for faster program execution in Android systems, and, based on our results, we propose an address space maintaining scheme for the rapid launching of programs for use in Linux-based systems. Our scheme utilizes the Copy on Write (CoW) technique in Linux systems as well as the Zygote technique of Android systems. In order to evaluate the proposed scheme, we implemented our scheme on Linux systems and performed several experiments. The experimental results show that the proposed scheme shortens the launching time up to 99%, compared to the existing technique.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.159-166
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• 2013

Recently, because the interest and needs in privacy protection are growing, smartcard-based remote user authentication schemes have been actively studied to provide the user anonymity. In 2008, Kim et al. first proposed an authentication scheme in order to ensure the user anonymity against both external attackers and the remote server and track malicious users with the help of a trusted trace sever. However, in 2010, Lee et al. showed that Kim et al.'s scheme cannot provide the user anonymity against remote server, which is because the server can trace users without any help of the trace server, and then proposed a improved scheme. On the other hand, in 2010, Horng et al. proposed an authentication scheme with non-tamper resistant smart cards, in which the non-tamper resistant smart card means that an attacker may find out secret information stored in the smart card through special data analysis techniques such as monitoring power consumption, to be secure against a variety of attacks and to provide the user anonymity against external attackers. In this paper, we will propose a remote user authentication scheme with non-tamper resistant smart cards not only to ensure the user anonymity against both external attackers and the remote server but also to track malicious users with only the help of a trusted trace sever.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.975-983
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• 2011

In this paper, we investigate how the IEEE 802.16 based wireless system can adopt the network coding. To avoid the problem of overhearing, we focus on the bidirectional traffic, where each end node exchanges network coded data over a relay node. The bidirectional traffic is usually observed in Internet, where TCP makes congestion control and error recovery based on the acknowledgement from the opposite direction. Thus, enhancing the spectral efficiency of wireless Internet through the network coding is expected. Our simulation with realistic radio characteristics and TCP-like traffic shows that the network coding improves the throughput by an average of 36 percent compared to the simple relay case.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.10
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• pp.865-873
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• 2013

In the cellular networks adopting femtocells, the macrocell users can suffer from severe interference by the femtocells. In this paper, we propose a distributed transmission power control scheme for femtocells to protect macrocell users. With the proposed scheme, when a macrocell user experiences outage due to severe interference, it informs the interfering femtocell base station (BS) of the outage occurrence, via the macrocell BS. Then, the femtocell BS reduces the transmission power to protect the macrocell user. The proposed scheme does not require too much control information among the macrocell BS, the macrocell users, and the femtocell BS. Moreover, the computational complexity in femtocell BS is very low. By using simulation, we show that the performance of the proposed scheme is good enough to use in practice, in spite of its simplicity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.37-42
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• 1999

This paper was studied on change for Marine Administration of telecommunications. Analysis method was studied of Policy Delphi. The three kinds of telecommunications network influence on Marine administration is National Information Infrastructure Network, Integrated Services Digital Network and Local Area Network. The five kinds of telecommunications service influence on Marine administration is Telecommuting Service, Electronic Approval Service, Teleconference Service, Electronic Data Interchange Service, and Internet Service. The results of this as follow: First, all Marine agency must be innovation. Second, Marine Administration must be use Telecommunications. Marine Administration must be for customer.

• Convergence Security Journal
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• v.22 no.1
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• pp.71-79
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• 2022

The smart grid system has emerged to maximize energy efficiency through real-time information exchange between power providers and consumers by combining information technology and power supply systems. The authentication schemes using blockchain in a smart grid system have been proposed, which utilize an edge server's architecture to collect and store electric power-related information and process data between a central cloud server and smart grid-IoT devices. Although authentication schemes are being proposed to enhance security in the smart grid environment, many vulnerabilities are still reported. This paper presents a new mutual authentication scheme to guarantee users' privacy and anonymity in a smart grid based on edge computing using blockchain. In the proposed scheme, we use the smart contract for the key management's efficiency, such as updating and discarding key materials. Finally, we prove that the proposed scheme not only securely establishes a session key between the smart grid-IoT device of the user and the edge server but also guarantees anonymity.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.345-352
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• 2014

In this paper, the CAD data for the optimal shape design obtained by isogeometric shape optimization is directly used to fabricate the specimen by using 3D printer for the experimental validation. In a conventional finite element method, the geometric approximation inherent in the mesh leads to the accuracy issue in response analysis and design sensitivity analysis. Furthermore, in the finite element based shape optimization, subsequent communication with CAD description is required in the design optimization process, which results in the loss of optimal design information during the communication. Isogeometric analysis method employs the same NURBS basis functions and control points used in CAD systems, which enables to use exact geometrical properties like normal vector and curvature information in the response analysis and design sensitivity analysis procedure. Also, it vastly simplify the design modification of complex geometries without communicating with the CAD description of geometry during design optimization process. Therefore, the information of optimal design and material volume is exactly reflected to fabricate the specimen for experimental validation. Through the design optimization examples of elasticity problem, it is experimentally shown that the optimal design has higher stiffness than the initial design. Also, the experimental results match very well with the numerical results. Using a non-contact optical 3D deformation measuring system for strain distribution, it is shown that the stress concentration is significantly alleviated in the optimal design compared with the initial design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.347-356
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• 2000

This paper was studied on influence analysis of Telecommunications Network in Electronic Government. Analysis method was studied of Policy Delphi. The five kinds of telecommunications network influence in Electronic Government is National Information Infrastructure Networt, Local Area Network, Integrated Services Digital Network Public Switched Telephone Network, and Cable TV Network. The five kinds of telecommunications network service influence in Electronic Government is Telecommuting Service, Internet Service, PC Telecommunications Networt Video Conference Service and Electronic Data Interchange Service. The five kinds of telecommunications influence in Electronic Government is as follow: First Telecommuting Service must be Constructed. Second, Public Administration Service must be improved. Third. citizen must be participated in decision making. Fourth, Public Administration duty service must be digitalizing. Fifth, Video Conference Service must be improved.

• Journal of the Korean Society for information Management
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• v.23 no.2
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• pp.167-183
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• 2006

This paper describes a metadata extraction technique based on natural language processing (NLP) which extracts personalized information from email communications between financial analysts and their clients. Personalized means connecting users with content in a personally meaningful way to create, grow, and retain online relationships. Personalization often results in the creation of user profiles that store individuals' preferences regarding goods or services offered by various e-commerce merchants. We developed an automatic metadata extraction system designed to process textual data such as emails, discussion group postings, or chat group transcriptions. The focus of this paper is the recognition of emotional contents such as mood and urgency, which are embedded in the business communications, as metadata.