• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.969-973
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• 2005

This paper presents a survey of software reliability modeling and it's application to pre-built software system combined with hardware such as numerical controller based on personal computer systems. Many a systems in these days are much more becoming software intensive and many software intensive systems are safety critical. For this reason, the technique well developed to measure of software reliability is very important for whom to assess such a system. This paper provides a brief idea of method to evaluate such a system's reliability based on hardware performance.

• International Journal of Contents
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• v.14 no.3
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• pp.17-26
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• 2018

To ensure safety of bridges, it is critical to inspect and assess physical and functional conditions regularly. Presently, most highway bridges in the U.S. are inspected visually. However, this method of inspection is often influenced by the bridge inspector's knowledge and experience. So, reliability and accuracy of inspection results may be problematic. To solve such problems, an extensive number of robotics systems and image processing techniques for bridge inspection methods have been proposed. These robotics systems and image processing techniques are used to measure various bridge conditions, such as apparent damage, displacement and dynamic characteristics. This paper provides a comprehensive review of robotics systems and image processing technologies used in bridge inspection.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.492-498
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• 2022

Process control systems used in most domestic petrochemical corporates today are based on the Windows platforms. As technology leans toward opened environment, the exposure risk of control systems is increasing. However, not many companies are preparing for various cyberattacks due to lack of awareness and misunderstanding of cyber intrusion. This study investigated the extent of how much exposed the petrochemical process control system is to security threats and suggested practical measures to reduce OT cybersecurity vulnerabilities. To identify the cyber threat status of process control systems, vulnerabilities of the Windows platform, a principal cyber threat factor, have been analyzed. For research, three major DCS providers in Korea and the discontinuation of Windows platform of 635 control systems were investigated. It was confirmed that 78% of the survey subjects were still operating in the discontinued windows platforms, and those process control systems were operated in a state vulnerable to cyber intrusions. In order to actively cope with these cyber threats, legal regulations such as designation of critical infrastructure for major petrochemical facilities which is implemented in advanced countries such as the United States are needed. Additionally, it is necessary to take the initiative in eradicating security threats to the process control systems by aggressively introducing security solutions provided from existing DCS suppliers. This paper was submitted to Professor Ko JaeWook's retirement anniversary issue.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.65-71
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• 2008

Recently, many critical control systems are developed using formal methods. When software applied to such systems is developed, the employment of formal methods in the software requirements specification and verification will provide increased. assurance for such applications. Earlier error of overlooked requirement specification can be detected using formal specification method. Also the testing and full verification to examine all reachable states using model checking to undertake formal verification are able to be completed. In this paper, we propose an eclectic approach to incorporate Z(Zed) formal language and 'Statemate MAGNUM' which is formal method tools using Statechart for applying to the railway signaling systems.

• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.151-164
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• 2017

This study is an empirical study on the relationships among success factors of six sigma(support of top management, education and training, performance-based reward, customer and quality focused thought) on change management activity and business performance. In particular, mediating effect of change management activity on the relationship between success factors of six sigma and business performance is empirically analysed to find causes and impacts among these variables. The study results are as follows: First, there were positive relationships between critical success factors of six sigma(except support of top management) and change management activity. Second, there was also a positive relationship between change management activity and business performance. Third, there were also positive relationships between critical success factors of six sigma and business performance. Finally, change management activity was partial mediating effects on the relationship between critical success factors of six sigma(education and training, performance-based reward, customer and quality focused thought) and business performance. On the other hand, support of top management had no mediating effect on business performance.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.7-13
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• 2011

A study on reliability estimation of sequential-ordered multiple failure modes, which are sequentially ordered between failure modes in a considering system, was performed. Especially, an approach to estimate the probabilities of failure modes has been proposed under an assumption that failure modes are mutually exclusive and sequentially ordered by only a critical variable. A feasibility of the proposed approach were studied by a practical example, which is a reliability estimation of passive safety systems for a probabilistic safety assessment(PSA) of a very high temperature reactor(VHTR) that is under development as a future nuclear system with enhanced safety features. It is difficult to define a robust failure state of this nuclear system because of its enhanced radiation release characteristics, so the new approach is a useful concept to estimate not only its safety but also a PSA. A feasibility study applied two failure modes(e.g., small and large release of radioactive materials) with considering the integrated behavior of this nuclear system. It is expected that the multiple release states for a practical estimation can be easily extended to the aforementioned example. It was found out that the proposed approach was a useful technique to cover the unfavorable features of this nuclear system as to performing a VHTR PSA.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.195-204
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• 2017

Predicting the failure life of automated manufacturing systems can reduce overall downtime, maintenance costs, and total plant operation costs. Therefore, there is a growing interest in fatigue failure mechanisms as the safety or service life assessment of manufacturing systems becomes an important issue. In particular, fretting fatigue is caused by repeated tangential stresses that are generated by friction during small amplitude oscillatory movements or sliding between two surfaces pressed together in intimate contact. Previous studies in fretting fatigue have observed size effects related to contact width such that a critical contact width exists where there is drastic change in the fretting fatigue life. However, most of them are the two-dimensional finite element analyses based on the plane strain assumption. The purpose of this study is to investigate the contact size effects on the three-dimensional finite element model of a finite width of a flat specimen and a cylindrical pad exposed to fretting fatigue. The contact size effects were analyzed by means of the stress and strain averages at the element integration points of three-dimensional finite element model. This study shows that the fretting fatigue life of manufacturing systems can be predicted by three-dimensional finite element analysis based on SWT critical plane model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1169-1176
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• 2013

PES have been recently required to implement railway industry for its application flexibility. The PES should be commensurated with railway safety requirements. It achieved its safety through redundant PES. The redundant systems run with voting functions. The successful major voting result becomes the output of the redundant system. The redundant system have to be synchronized to vote each output results. This paper proposed an algorithm for synchronizing and a voter. The proposed algorithm and the voter are verified using simulation.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.233-243
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• 2023

In modern society, since the expansion of the e-commerce market and the spread of the pandemic, face-to-face business are gradually changing to non-face-to-face. In the logistics industry, the demand for unmanned courier storage is increasing due to lack of loading space from urbanization and courier theft accidents. As the demand for unmanned parcel lockers increases, improved functions such as food storage and efficient space loading are required. This study develops an integrated model-based evaluation procedure of product based on performance factors according to the IEC 61508 standard for newly unmanned parcel storage devices with active loading technology, and derive Critical Technology Element based on the product's core functions and performance goals. As proposing these research, We expect improve the safety and reliability of development targets by identifying and evaluating elements.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.85-85
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• 2003