• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.43-48
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• 2014

The door system for railway vehicles is the critical device directly influences on safety and satisfaction of passengers, Recently, electrical type of passenger door system is widely used for EMU type train instead of pneumatic type of passenger door system. The estimation of MTBF and failure rates for electrical type door system is essential. The manufacturor simply provides intrinsic reliability data for the railway operator. But actual reliability data based on operation and maintenance data is not complying with intrinsic reliability. In this study, operation and failure data associated with electrical door system were analyzed in order to determine actual MTBF and failure data. Intrinsic reliability data and service reliability data were studied to finallize much more practical and reliable actual reliability. Relax 2011 was used to predict intrinsic reliability and 217Plus model was also used to estimate of actual reliability data based on field data. Furthermore, it is necessary to keep studying on reliability prediction methodology and applying it in the field and doing research on improvement of reliability through feedback as well.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.6
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• pp.267-276
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• 2021

The automotive industry and academic research have been continuously conducting research on standardization such as AUTOSAR (AUTomotive Open System ARchitecture) and ISO26262 to solve problems such as safety and efficiency caused by the complexity of electric/electronic architecture of automotive. AUTOSAR is an automotive standard software platform that has a layered structure independent of MCU (Micro Controller Unit) hardware, and improves product reliability through software modularity and reusability. And, ISO26262, an international standard for automotive functional safety and suggests a method to minimize errors in automotive ECU (Electronic Control Unit)s by defining the development process and results for the entire life cycle of automotive electrical/electronic systems. These design methods are variously applied in representative automotive safety-critical systems. However, since the functional and safety requirements are different according to the characteristics of the safety-critical system, it is essential to research the AUTOSAR functional safety design method specialized for each application domain. In this paper, a software functional safety mechanism design method using AUTOSAR is proposed, and a new failure management framework is proposed to ensure the high reliability of the product. The AUTOSAR functional safety mechanism consists of memory partitioning protection, timing monitoring protection, and end-to-end protection. The fault management framework is composed of several safety SWCs to maintain the minimum function and performance even if a fault occurs during the operation of a safety-critical system. Finally, the proposed method is applied to the Shift-by-Wire system design to prove the validity of the proposed method.

• Steel and Composite Structures
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• v.4 no.6
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• pp.419-435
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• 2004

The safety level of a structural system designed per code specifications can not be inferred directly from the reliability of members due to the load redistribution and nonlinear inelastic structural behavior. Comparison of the system and member reliability, which is scarce in the literature, is likely to indicate any possible inconsistency of design codes in providing safe and economical designs. Such a comparative study is presented in this study for moment resisting two-dimensional steel frames designed per AISC LRFD Specifications. The member reliability is evaluated using the resistance of the beam-column element and the elastic load effects that indirectly accounts for the second-order effects. The system reliability analysis is evaluated based on the collapse load factor obtained from a second-order inelastic analysis. Comparison of the system and member reliability is presented for several steel frames. Results suggest that the failure probability of the system is about one order of magnitude lower than that of the most critically loaded structural member, and that the difference between the system and member reliability depends on the structural configuration, degree of redundancy, and dead to live load ratio. Results also suggest that the system reliability is less sensitive to initial imperfections of the structure than the member reliability. Therefore, the system aspect should be incorporated in future design codes in order to achieve more reliability consistent designs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.128-138
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• 2011

Objectives: It has been pointed out that there are problems in handling and managing chemicals due to trade secrets of Material Safety Data Sheet(MSDS). To date, some company intentionally leave out of several parts and use an inaccurate expression in MSDS. In particular, with the result of the inspection of the government and labour community, it is required that the 2nd section in MSDS included the composition and information on ingredients has to be provided with comprehensive expression to secure more reliability. Methods: Therefore, this study is aimed: 1) to recognize the current status of trade secrets of MSDS in workplaces with both domestic manufacturers of chemical products and multinational corporations; 2) to make contributions to prevention of the industrial accidents by providing the accurate information of MSDS; 3) to improve the risk communication system related with chemicals; 4) to impress workers on the importance of right of known for MSDS. With the result we analyzed the status of trade secrets in MSDS in 73 companies, such as petrochemistry production, paint production, metal processing oil production, detergent production, and international company related with chemicals, we have found that 38,150 (45.5%) have the trade secrets parts in the total number of 83,832 in MSDS. Also, based on the 288 MSDS gathered by the Occupational Safety and Health Research Institute (OSHRI) from 2005 to 2009, 41.7% of the MSDS are classified into the trade secrets. Conclusions: Therefore, to procure an assurance system of MSDS, we suggest that a MSDS picking up and checking system be legislated in the Occupational Safety and Health Act to protect workers from the unidentified chemical hazards due to the secret trade of MSDS.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.125-130
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• 2008

To optimize the selected reinforcing method for application to PSC Beam bridges, the reliability analysis was performed with consideration for the increase and decrease of the member section based on the standard design section, and the minimum life-cycle cost(LCC) was calculated from this analysis with consideration for the aleatory uncertainty. Moreover, the mean, 50%, 75%, and 90% distributions of the analysis results were re-evaluated quantitatively by considering the effect of the epistemic uncertainty. The reliability results gained from the application of the reinforcing method, as well as the optimal design method based on the minimum LCC, will provide more reasonable design criteria for the PSC Beam bridges.

• Safety and Health at Work
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• v.15 no.1
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• pp.80-86
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• 2024

Background: The Work Ability Index (WAI) is an instrument that measures work ability. The wide dispersion of the WAI internationally has led to its adaptation for use in different countries. This study aimed to evaluate the psychometric properties of the Spanish version of the WAI. Methods: A methodological design was used over an opportunistic sample of 233 workers in the aeronautical industry in Spain. Reliability was evaluated through internal consistency. Factorial validity, known groups, and convergent validity were tested. Results: The Cronbach's alpha and item-total correlation indicated an adequate internal consistency. The confirmatory factor analysis, performed to evaluate the factorial validity, found adequate fit indices for a two-factor solution with a high correlation between the factors. Factor 1, "Subjectively estimated work ability and resources", was composed of 3 subscales and factor 2, "Ill-health-related", of 2 subscales. Subscales 4 and 6 had loading in both factors. Workers under 45 years of age obtained higher significant scores than older ones. Convergent validity was also evidenced since WAI was highly correlated with self-assessment of health status. Conclusions: The Spanish version of the WAI has shown evidence of reliability and validity in this study, supporting its use in individual and collective health surveillance by occupational health professionals. The factorial solution that was found has previously been reported in another international context. However, further research is needed to resolve the discrepancies detected in the role of some subscales between other national and international studies.

• Journal of Applied Reliability
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• v.15 no.3
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• pp.181-191
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• 2015

Change in labor time is affecting occupational safety and health. Recently reduction in labor time brought innovational operation method, investment in plant and equipment, and flexible labor time in some companies, thereby affecting working conditions for labourers. However, working conditions for some vulnerable social groups have deteriorated. As a result, they are becoming more exposed to risk factors such as injury and emotional stress. In this study we use 2014 KWCS data in order to find the social and demographic characteristics in Korean working conditions. To this end, we use exploratory data analysis approach to find the relationship between some of the important variables in the KWCS data. We also use Press-State-Response model to find which group of people are vulnerable to Press and State. We find that women, people over age 50 and business owners are more vulnerable to Press and State than men, people below age 50 and wage workers.

• Journal of the Ergonomics Society of Korea
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• v.17 no.3
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• pp.117-126
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• 1998

Safety aspect in the manufacturing facility or at the construction site is increasingly emphasized in Korea for last a decade. As a result, the number of industrial accident is decreased slowly by improving the reliability of equipments and human performance through organizational efforts. This paper proposes a mathematical model to estimate and predict the human reliability level corresponding to the worker's job experience. For this purpose, we used the statistics of industrial accidents issued by the Department of Labor in the years of 94-96. The methodology developed in this research will provide a basis for better cost estimation in planning labor policy in the early stage of a project. We believe that this effort would eventually lead to a basis for a new approach to the safety planning.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.180-190
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• 1997

A new method in the fault tree analysis (FTA) for the reliability calculation is suggested. Two steps are necessary in traditional method in evaluation of the occurrence probability of top event in fault tree (FT). The first step is to find the minimal outsets, and the second one is to substitute the result into the poincare equation. In order to reduce the enormous computing time of this method, lots of rapid algorithms have been developed. Almost of all achievements were, however, based on the partial structural properties of FT. In this paper, the FT is transformed to a non-linear graph G which has the same minimal outsets of original n, and then the reliability is calculated using the domination theory. In this new method, the required number of equation terms are at most $2^n$ (n is node number of graph G), while $2^m$-1 (m is the number of minimal cutsets) calculation terms are required in the poincare equation in traditional method. Since m>>n in general. our new method reduces the calculation time significantly.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.713-720
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• 2008

This article deals with a case study on determining the replacement interval for the extraction motor in KTX. The reliability is analysed with the field data from 42 months. The effect of the replacement interval on service reliability, availability, safety and lifecycle cost are evaluated through simulation which is done by the commercial tool, Availability Workbench AvSim Module. As the results of the analyses, a new replacement interval is presented to reduce the lifecycle cost while service reliability, safety and availability are satisfactory.