• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.10-17
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• 2010

Safety-critical systems related to the railway communications are currently undergoing changes. Mechanical and electro-mechanical devices are being replaced by programmable electronics that are often controlled remotely via communication networks. Therefore designers and operators now not only have to contend with component failures and user errors, but also with the possibility that malicious entities are seeking to disrupt the services provided by theirs systems. Recognizing the safety-critical nature of the types of communications required in train control operations, the communications infrastructure will be required to meet a number of safety requirements such as system faults, user errors and the robustness in the presence of malicious attackers who are willing to take determined action to interfere in the correct operation of a system. In this paper, we proposed the safety strategies employed in the railway communications and a security mechanism for Korean railway communication system. Also, we presented the developed means for validation and determination of communication safety based on the proposed security mechanism in the railway system.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.1-6
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• 2016

Severity and frequency of industrial accidents are typically used to assess the "absolute" risk associated with the industrial machines and devices ("items") which are subject to safety certification or self-declaration of conformity. However, the "relative" risk associated with a particular item can further be assessed based on unit severity and unit frequency where the total number of item in use is taken into account. This study first attempts to estimate the total number of each item in use which was recently selected for safety certification or self-declaration of conformity. The appropriateness of such selection is recapitulated based on the relative risk involved. Analysis results indicate that depending on items, the relative risk is differentiated from the absolute risk. Recent selection of items for safety certification or self-declaration of conformity is then revisited for its validity. The relative risk based on unit severity and unit frequency of industrial accidents, together with the absolute risk, may be used to further categorize items for safety certification or self-declaration of conformity in the future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.641-645
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• 2017

In this study, an epoxy insulation barrier for high voltage GIS was developed using epoxy and a filler with a Young's modulus of 11 GPa. The material was investigated using a simulation of the principal stress, displacement, and safety factors while optimizing the profile shape. The simulation showed that thelarger Young's modulus of the $Al_2O_3$ filler compared to the $SiO_2$ in the epoxy insulation can contribute to an increase in resistance to mechanical fracturing for theoptimized profile barrier in high voltage GIS. In addition, the safety factor was improved by 10%. It can be concluded that the mechanical fracturing properties of the insulation barrier can be enhanced by increasing the content of the elastic filler, $Al_2O_3$, for high voltage GIS applications.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1742-1752
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• 2005

This paper presents a Multiple Target Tracking (MTT) Adaptive Cruise Control (ACC) system which consists of three parts; a multi-model-based multi-target state estimator, a primary vehicular target determination algorithm, and a single-target adaptive cruise control algorithm. Three motion models, which are validated using simulated and experimental data, are adopted to distinguish large lateral motions from longitudinally excited motions. The improvement in the state estimation performance when using three models is verified in target tracking simulations. However, the performance and safety benefits of a multi-model-based MTT-ACC system is investigated via simulations using real driving radar sensor data. The MTT-ACC system is tested under lane changing situations to examine how much the system performance is improved when multiple models are incorporated. Simulation results show system response that is more realistic and reflective of actual human driving behavior.

• International Journal of Safety
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• v.6 no.2
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• pp.13-16
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• 2007

This study focuses on the trends and issues of improving safety management of elevators in Korea. Frequency and severity of accidents in relation to conditional pass in periodic inspection, maintenance, market surveillance are analyzed based on the statistical data and social cost due to a variety of related fields in managing elevator safety was estimated first. The results of statistical analysis performed in this study will provide logical basis and future direction for improving the safety management system. The role of certification and supervision is particularly addressed to reduce the related accidents and the social cost. The effectiveness of such procedures can be found from the results of simple statistical analysis.

• International Journal of Safety
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• v.4 no.1
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• pp.8-13
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• 2005

Design of manufacturing process, in general, facilitates the creation of new process that may potentially harm the workers. Design of safety-guaranteed manufacturing process is, therefore, very important since it determines the ultimate outcomes of manufacturing activities involving safety of workers. This study discusses application of information-theoretic measure (entropy) to safety assessment of manufacturing processes. The idea is based on the general principles of design and their applications. Some examples are given.

• International Journal of Safety
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• v.5 no.2
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• pp.12-17
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• 2006

Operations of human-centered robot, in general, facilitates the creation of new process that may potentially harm the human operators. Design of safety-guaranteed operation of human-centered robots is, therefore, important since it determines the ultimate outcomes of operations involving safety of human operators. This study discusses the application of information-theoretic measures to safety assessment of human-centered robotic operations. Some examples are given.

• Tribology and Lubricants
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• v.40 no.3
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• pp.97-102
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• 2024

The next-generation Molten Salt Reactor is known for its high safety because it uses nuclear fuel dissolved in high-temperature molten salt, unlike traditional solid atomic fuel methods. However, the high-temperature molten salt causes severe corrosion in internal structural materials, threatening the reactor's safety. Therefore, it is crucial to investigate the high-temperature corrosion resistance and wear performance of materials used in reactors to ensure safety. In this study, the high-temperature corrosion resistances and wear performances of corrosion samples in a NaCl-MgCl2-KCl (20-40-40 [wt%]) molten salt are investigated to evaluate the applicability of economically viable stainless steels, 316SS and 304SS. Hastelloy C276 and a new alloy containing a small amount of Nb are used as reference samples for comparative analysis. The mass loss, mass loss rate per unit volume, and surface roughness of each sample are measured to understand the corrosion mechanisms. Scanning electron microscopy and energy-dispersive spectroscopy analyses are employed to analyze the corrosion mechanisms. Wear tests on the corroded samples are also conducted to assess the extent of corrosion. Based on the experimental results, we predict the lifespans of the materials and evaluate their suitability as candidate materials for molten salt reactors. The data obtained from the experiments provide a valuable database for structural materials that can enhance the stability of molten salt reactors and recommend high-temperature corrosion-resistant materials suitable for next-generation reactors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.1019-1027
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• 2014

Vehicle-into-pedestrian traffic accidents show a very high mortality rate compared to their frequency of occurrence. Throughout the world, governments and insurance companies tend to establish and implement new safety standards for pedestrian protection. In order to improve the performance of pedestrian protection, the Korean government has evaluated the pedestrian safety of vehicles under the Korea New Car Assessment Program (K-NCAP) since 2007. The pedestrian protection performance has improved gradually, but it remains insufficient. A pedestrian protection system consisting of a hood lift system and a pedestrian airbag can be a solution to pedestrian safety. A pedestrian airbag design procedure based on a newly defined design scenario is introduced to reduce the head injury criterion of pedestrians. The proposed design scenario is discussed from a practical viewpoint and applied to manufacture pedestrian protection systems.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.42-47
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• 2004

In this paper, we analyzed on the characteristics of the stranded wire disconnected by repeated stress. The stranded wires that were used in the experiment are PVC insulated flexible cords(VCTFK: Vinyl Insulated Vinyl Cabtyre Cord Flat-type) of $0.75mm^2,\;1.25mm^2,\;and\;2.0mm^2$. They are used to connect the load in low voltage. The stranded wires disconnected by repeated stress were magnified with optical microscope. Using X-ray, the disconnected wire were photo-graphed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl cap tire ellipse type cords under bending stress, VCTFK of $1.25mm^2$ was the strongest of them. When it was bent $826.3\pm7$ times, it appeared the disconnected tendency that element wires of VCTFK of $1.25mm^2$ are more about 1.67 times than element wires of VCTFK of $0.75mm^2$. In mechanical strength, VCTFK of $1.25mm^2$ is higher about 1.7 times than VCTFK of $0.75mm^2$. Therefore, we found out that mechanical strength was higher, when the wire had a lot of element wires. In comparison with bending stress, VCTFK of $1.25mm^2$ is the strongest among samples, and it is the most useful in wires of movable type.