• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.637-659
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• 2021

Since the creation of the first Bitcoin blockchain in 2009, the number of cryptocurrency users has steadily increased. However, the number of hacking attacks targeting assets stored in these users' cryptocurrency wallets is also increasing. Therefore, we evaluate the security of the wallets currently on the market to ensure that they are safe. We first conduct threat modeling to identify threats to cryptocurrency wallets and identify the security requirements. Second, based on the derived security requirements, we utilize attack trees and Bayesian network analysis to quantitatively measure the risks inherent in each wallet and compare them. According to the results, the average total risk in software wallets is 1.22 times greater than that in hardware wallets. In the comparison of different hardware wallets, we found that the total risk inherent to the Trezor One wallet, which has a general-purpose MCU, is 1.11 times greater than that of the Ledger Nano S wallet, which has a secure element. However, use of a secure element in a cryptocurrency wallet has been shown to be less effective at reducing risks.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.203-211
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• 2016

A Satellite Based Augmentation System (SBAS) is a system that provides positioning information with high and accurate reliability to users who require ensuring high safety such as airplane taking off and landing. A continuous performance evaluation on navigation safety facilities shall be performed to determine whether developed systems meet the required performance before and after the operation. In this paper, SBAS position domain analysis is discussed in relation to analysis items for performance evaluation. The performance evaluation on the SBAS in the position domain shall conduct analysis on accuracy, integrity, continuity, and availability, which are items in the required navigation performance (RNP). In the paper, position domain analysis was conducted with regard to the Wide Area Augmentation System (WAAS) in the USA and the European Geostationary Navigation Overlay Service (EGNOS), which were developed already and now under operation. The analysis result showed that each of the systems satisfied the APV-I performance requirements recommended by the International Civil Aviation Organization (ICAO) with regard to daily data. It is necessary to verify using long-term data, whether the performance requirements in the RNP items are satisfied for system certification.

• Asia pacific journal of information systems
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• v.5 no.2
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• pp.101-129
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• 1995

This paper proposes a form-based distributed database design methodology ($FD^3$). The methodology consists of five design phases such as (i) form requirement analysis (ii) schema integration (iii) distribution analysis (iv) distribution design, and (v) local logical/physical design. In the $FD^3$, all the important design information for each phase is obtained by using an organizations forms, Users requirements are analyzed by using forms that contain logical and quantitative information for distribution design. $FD^3$ resolves naming conflicts by employing SQLs based on the form field data in the schema integration phase. Furthermore, $FD^3$ enhances the quality of distributed database design by incorporating communication costs into the design model. A real-life case is illustrated to demonstrate the usefulness of the $FD^3$.

• Proceedings of the Korean Institute of Interior Design Conference
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• 1999.04a
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• pp.83-86
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• 1999

The purpose of this study is to make interior environment which can support the education effectively through acceptance of the requirements of users about the environmental factors of learning spaces for the visually impaired students. For them, researcher investigated the literature cited and did the field survey. And also, this researcher analyzed user's satisfaction extent for structure, design, and technical environment factors by the evaluation elements. On the basis of the result of analysis, Two rooms which had big problems for physical environment were selected. And then the design recommendations focusing on environmental factors - circulation, furniture arrangement, colour, lighting etc. - were proposed by this researcher on the basis of space user's requriement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.3
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• pp.446-458
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• 2013

Recently, energy-efficient cellular transmission has received considerable research attention to improve the energy efficiency of wireless communication. In this paper, we consider a cellular network consisting of one base station (BS) and multiple user terminals and explore the network coding for enhancing the energy efficiency of cellular downlink transmission from BS to users. We propose the network coded cellular transmission scheme and conduct its energy consumption analysis with target outage probability and data rate requirements in Rayleigh fading environments. Then, the energy efficiency in Bits-per-Joule is further defined and analyzed to evaluate the number of bits delivered per Joule of energy cost. Numerical results show that the network coded cellular transmission significantly outperforms the traditional cellular transmission in terms of energy efficiency, implying that given a Joule of energy cost, the network coded cellular transmission scheme can deliver more bits than the traditional cellular transmission.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1693-1701
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• 2010

In this paper, requirements of efficient group key creation in multiple hierarchy structure environment with clear distinction of hierarchical roles within organizations are explained and the method of creating a group key that satisfies such requirements is proposed. The proposed method creates the group key through logical sum operation of hierarchy identifier created using uni-directional hash chain and group identifier randomly created according to the access right. The problem of excessive possession of key information by upper group users in the existing static group key creation technique was resolved. At the same time, lower group users were prevented from deducing key information of upper group users. In addition, as a result of comparative analysis performed with an experiment on existing super group key creation technique and multiple hierarchy group key method, the proposed method was found to be equivalent or superior to existing method in terms of various items including the total number of keys created, the number of keys possessed by users, the number of keys used for encoding and decoding of information, and expandability of keys.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.959-968
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• 2017

Electrical safety monitoring System (ESMS) is a critical component in modern power systems, which is characterized by large-scale access points, massive users and versatile requirements. For convenience of the information integration and analysis, the software development, maintenance, and application in the system, the cloud platform based ESMS is established and assessed in this paper. Firstly the framework of the system is proposed, and then the assessment scheme with a set of evaluation indices are presented, by which the appropriate cloud product can be chosen to meet the requirements of a specific application. Moreover, to calculate the weights of the evaluation indices under uncertainty, an improved interval AHP method is adopted to take into consideration of the fuzziness of expert scoring, the qualitative consistency test, and the two normalizations in the process of eigenvectors. Case studies have been made to verify the feasibility of the assessment approach for ESMS.

• Journal of Information Technology Services
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• v.12 no.1
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• pp.323-340
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• 2013

As the importance of collaboration becomes critical in today's open and complex business environment network, the issues and solutions on compatibility and reusability between different kinds of applications are being increasingly important as well in systems analysis and design. And therefore, service-centered SOA is receiving attention in such business environment as a strategic approach that makes possible for prompt action according to the needs of users and business process. Various implementation methodologies have been proposed for SOA, however, in practical aspects most of them have some problems since they fail to propose specific policies in definition and identification of services for the exact user requirements and business situations. To solve or alleviate those problems, this paper suggests a new service identification model based on hierarchical ontology, where three different ontologies such as business ontology, context ontology and service ontology are proposed to define the relationship and design the link between user requirements, business process, applications and services. Through a suggested methodology in this paper, it would be possible to provide proactive services that meets a variety of business environments and demands of user. Also, since the information can be modified adaptively and dynamically by hierarchical ontology, this study is expected to play a positive role in increasing the flexibility of systems and business environments.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.23 no.1
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• pp.91-111
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• 2012

With the rapid expansion of web information, conventional information retrieval techniques are becoming inadequate for users and often result in disappointment, because a couple of simple keywords can easily produce information too much. This study aims at the development of Web information retrieval techniques based on semantics to improve the quality of understanding for information. To achieve the goal, this study analyzes technologies and current status of researches on semantic information retrieval. With the results which are requirements, system architecture and indexing method, this study proposes the system architecture of semantic-based information retrieval system.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.97-103
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• 2014

The access control means the process to record and manage access restrictions and permits for protecting information in records. This paper emphasizes the control of access and authorization based on the roles and the data using activities of users as task performers. Also, it requires to gain the necessary approval in advance for important tasks such as mass inquiry and change on important information to influence the very existence of the whole organization. And then, it suggests that it is necessary to control some session of information with non-activity for certain time. Generally, this paper is to explain security elements of access control through various cases.