• KIPS Transactions on Software and Data Engineering
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• v.4 no.1
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• pp.1-8
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• 2015

Safety critical systems require exhaustive verification of safety properties, because even a single corner-case fault can cause a critical safety failure. However, existing verification approaches are too costly in terms of time and computational resource required, making it hard to be applied in practice. In this paper, we implemented a tool for minimizing the size of the verification target w.r.t. verification properties to check, based on program slicing technique[1]. The efficacy of program slicing using our tool is demonstrated in a case study with a verification target Trampoline[3], which is an open source automotive operating system compliant with OSEK/VDX[2]. Experiments have shown enhanced performance in verification, with a 71% reduction in the size of the code.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.751-757
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• 2007

This paper is concerned with the development of the requirements for railway safety support information systems. The five safety elements at the system level have been modeled based on the enterprise architecture approach. Specifically, the modeling has been carried out as follows. First, the requirements are derived according to EIA-632 process. Also, the possible scenarios on the accident-investigation-support are developed from the help of relevant personnel in the area. The developed scenarios are reflected in modeling the operational and system architectures of DoDAF approach using a CASE tool. From this architecture model, we can easily get the specifications required for the operations. These results can give the improved understanding of the railway safety system to the members of diverse teams and areas working for the system development.

• Proceedings of the KSR Conference
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• 2003.10a
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• pp.125-130
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• 2003

Korean High Speed Train (KHST) designed to operate at 350km/h has been tested on high speed line in JungBu site since it was developed in 2002. The dynamic performances of railway vehicle are generally stability, safety and ride comfort. The stability performance of KHST was proved that it is stable at 400Km/h through Roller Rig test. The safety and ride comfort need to be predicted the capability of it at 350km/h by the on-line test because KHST is testing at 300km/h up to now. Therefor, in this paper, the safety and ride comfort at 350km/h are predicted the performance using the acceleration results at 300kw/h and these results show that the KHST's dynamic performances are very good. Also, it illustrate the two cases occurred the abnormal vibration of KHST during some on-line tests. The first case is that the variation of vertical acceleration of wheel is analyzed when an abrasion occur on wheel. The second case is that the lateral acceleration of wheel, bogie and body are analyzed when the KHST is unstable at high speed. The occurrences of these special phenomena were due to the some faults of the suspension and braking systems and the faults were improved. In present, it is testing with safety.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.306-312
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• 2017

The purpose of this research is to introduce the technical standard of accident sequence precursor (ASP) analysis, and to propose a case study using the dynamic-probabilistic safety assessment (D-PSA) approach. The D-PSA approach can aid in the determination of high-risk/low-frequency accident scenarios from all potential scenarios. It can also be used to investigate the dynamic interaction between the physical state and the actions of the operator in an accident situation for risk quantification. This approach lends significant potential for safety analysis. Furthermore, the D-PSA approach provides a more realistic risk assessment by minimizing assumptions used in the conventional PSA model so-called the static-PSA model, which are relatively static in comparison. We performed risk quantification of a steam generator tube rupture (SGTR) accident using the dynamic event tree (DET) methodology, which is the most widely used methodology in D-PSA. The risk quantification results of D-PSA and S-PSA are compared and evaluated. Suggestions and recommendations for using D-PSA are described in order to provide a technical perspective.

• Geotechnical Engineering
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• v.4 no.2
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• pp.5-14
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• 1988

A probabilistic model for the progressive failure in a homogeneous soil slope consisting of strain-softening material is presented. The local safety margin of any slice above failure surface is assumed to follow a normal distribution. Uncertainties of the shear strength along potential failure surface are expressed by one-dimensional random field models. In this paper, only the case where failure initiates at toe and propagates up to the crest is considerd. The joint distribution of the safety margin of any two adjacent slices above the failure surface is assumed to be bivariate normal. The overall probability of the sliding failure is expressed as a product of probabilities of a series of conditional el.eats. Finally, the developed procedure has been applied in a case study to yield the reliability of a cut slope.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2044-2045
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• 2008

This paper was studied fault possibility of glass insulator through the proper vibration and field vibration comparison. The proper vibration of 1 cell glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. From the FFT analysis of viaduct and open route, in the case of positive direction, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in the case of negative direction, the vibration did not cause big effect. In comparison with the proper vibration of glass insulator, the resonance was not observed.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.111-117
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• 2016

Natural disasters can cause major accidents in chemical facilities where they can lead to the release of hazardous materials which in turn can result in fires, explosions or toxic dispersion. Technological disasters triggered by natural disasters are referred to as NaTech(Natural Disaster Triggered Technological Disaster). These trends increase the probability of catastrophic future disasters and the potential for mass human exposure to hazardous materials released during disasters. In the present study, we proposed some methods for effective disaster management by conducting case study of major NaTech. First, establishing information sharing system of chemical accident for stakeholders and improving disaster manuals and standards of central and local government and co-operation support system. Second, activating information service of emergency planning and community right to know. Third, improving the integrated chemical accident database including NaTech accidents.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.189-196
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• 2012

Fire is one of the greatest threats to historical buildings not only to the building's occupants but also to the building's structure and contents. The purpose of this research is to evaluate fire risk in historical buildings in Korea through a series of survey and review. In this research, a multicriteria decision-making approach involving Analytical Hierarchy Process has been designed to determine a weighted index to identify factors and quantify fire risk. Fire risk ranking systems of historical building has been developed in some applications, for example, BOCA, WISCONSIN, FSES and HFRI. According to the such derived fire risk indexing, the Human Activity index showed the highest risk, followed by Historic Buildings, Fire Safety Systems, and then Natural Environmental Causes. Comparison of these factors indicates that the derived risk values differ from case to case. It is proposed that a performance-based design approach should consider the building & occupant characteristics, locations and historical significance, resulting in a more accurate and effective evaluation of fire risk.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.327-348
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• 2008

A risk-informed regulatory approach implies that risk insights be used as supplement of deterministic information for safety decision-making purposes. In this view, the use of risk assessment techniques is expected to lead to improved safety and a more rational allocation of the limited resources available. On the other hand, it is recognized that uncertainties affect both the deterministic safety analyses and the risk assessments. In order for the risk-informed decision making process to be effective, the adequate representation and treatment of such uncertainties is mandatory. In this paper, the risk-informed regulatory framework is considered under the focus of the uncertainty issue. Traditionally, probability theory has provided the language and mathematics for the representation and treatment of uncertainty. More recently, other mathematical structures have been introduced. In particular, the Dempster-Shafer theory of evidence is here illustrated as a generalized framework encompassing probability theory and possibility theory. The special case of probability theory is only addressed as term of comparison, given that it is a well known subject. On the other hand, the special case of possibility theory is amply illustrated. An example of the combination of probability and possibility for treating the uncertainty in the parameters of an event tree is illustrated.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.43-48
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• 2011

Estimation of accident costs would set a sound criterion on which invest judgement for work improvement would be decided. Unfortunately, however, the professional agency and most companies in Korea still adopt the conventional cost estimation method based on Heinrich's theory would not be applicable any more since it was developed about a century ago. This research was carried out to confirm the validity of conventional accident cost estimation method. With 110 accident cases occurred in an autoglass manufacturing plant for last 7 years, post-accident treatment procedure was simplified as a model with several phases, and practical costs were analyzed case by case. The results showed that, as expected, the company should the largest portion of loss due to accidents, and that mean indirect cost were 10.10(${\pm}20.70$) times as much as direct cost estimated by conventional method. Therefore, finally, accident types and items influenced much on accidents costs were analyzed and discussed.