• Journal of the Korean Society for Railway
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• v.9 no.5 s.36
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• pp.601-605
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• 2006

Reliability of the Railway signaling system which is safety critical is determined by reliability of hardware and software. Reliability of hardware is easily predicted and demonstrated through lots of different studies and environmental tests, while that of software is estimated by the iterative test outcomes so estimates of reliability will depend on the inputs. Combinations of inputs to and outputs from the software may be mostly combinatoric and therefore all the combinations could not be tested. As a result, it has been more important to calculate reliability by means of a simpler method. This paper identifies the reliability prediction equation applicable to reliability prediction for railway signaling system software, and performs the simulation of onboard equipment of automatic train control for high speed train to review reliability prediction and validity.

• Journal of the Korea Safety Management & Science
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• v.26 no.1
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• pp.63-74
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• 2024

The objectives of this study is to classify evacuation types, derive the characteristics of 4 types, develop and discover evacuation routes within the performance hall space, and present the statistical classification results of the evacuation classification model by classification type. To achieve this purpose, the characteristics of each evacuation type's four types are applied through a network reliability analysis method and utilized for institutional improvement and policy. This study applies for the building law, evacuation and relief safety standards when establishing a performance hall safety management plan, and reflects it in safety-related laws, safety standards, and policy systems. Statistical data by evacuation type were analyzed, and measurement characteristics were compared and analyzed by evacuation types. Evaluate the morphological similarity and reliability of evacuation types according to door width and passage length and propose the install position of evacuation guidance sign boards. The results of this study are expected to be used as basic data to provide operation strategies for safety facility evacuation information sign boards according to evacuation route classification types when taking a safety management plan. The operation strategy for the evacuation sign boards installation that integrates employee guidance and safety training is applied to the performance hall safety management plan. It will contribute to establishing an operational strategy for performance space safety when constructing performance facilities in the future.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.240-247
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• 1993

The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult especially when the bridges are highly redundant and significantly deteriorated or damaged. This paper is intended to propose a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. It may be emphasized that this approach is very useful for the evaluation of the deterministic system redundancy and reserve strength which are measured in terms of either probabilistic system redundancy factor and reserve factor or deterministic system redundancy factor and reserve factor. The system reliability of bridges is formulated as a parallel-series model obtained from the FAM(Failure Mode Approach) based on the major failure mechanisms. AFOSM and IST methods are used for the reliability analysis of the proposed models. The proposed approach and method for the system redundancy and reserve safety/strength are applied to the safety assessment of actual RC and steel box-girder bridges. The results of the evaluation of reserved system safety or bridge system-strength in terms of the system redundancy and the system safety/strength are significantly different from those of element reliability-based or conventional methods.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.53-61
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• 2019

This study performs reliability analysis of three-dimensional temporary shoring structures with three different models. The first model represents a field model which does not have diagonal bracing members. The installation of bracing members is often neglected in the field for convenience. The second model corresponds to a design model which has the bracing members with the hinge connection of horizontal and bracing members at joints. The third model is similar to the second model but the hinge connection is replaced with partial rotational stiffness. The reliability analysis results revealed that the vertical members of the three models are safe enough in terms of axial force, but the vertical and horizontal members exhibit a big difference among the three models in terms of combination stress of axial force and bi-axial bending moments. The field model showed significant increase in failure probability for the horizontal member, and thus the results demonstrate that the bracing member should be installed necessarily for the safety of the temporary shoring structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.884-891
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• 2020

The collapse of bridges can cause massive casualties and economic losses. Therefore, it is thus essential to evaluate the structural safety of bridges. For this task, structural reliability analysis, considering various bridge-related uncertainty factors, is often used. This paper proposes a new computational platform to perform structural reliability analysis for bridges and evaluate their structural safety under various loading conditions. For this purpose, a software package of reliability analysis, Finite Element Reliability Using MATLAB (FERUM), was integrated with MIDAS/CIVIL, which is a widely-used commercial software package specialized for bridges. Furthermore, a graphical user interface (GUI) control module has been added to FERUM to overcome the limitations of software operation. In this study, the proposed platform was applied to a simple frame structure, and the analysis results of the FORM (First-Order Reliability Method) and MCS (Monte Carlo simulation), which are representative reliability analysis methods, were compared. The proposed platform was verified by confirming that the calculated failure probability difference was less than 5%. In addition, the structural safety of a pre-stressed concrete (PSC) bridge was evaluated considering the KL-510 vehicle model. The proposed new structural reliability analysis platform is expected to enable an effective reliability-based safety evaluation of bridges.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.387-401
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• 2002

The Digital Engineered Safety Feature Actuation System (DESFAS) of nuclear power plants actuates safety systems to mitigate severe accidents occurred in nuclear power plants. The reliability of the system should be evaluated in order to meet the reliability criteria of nuclear power plants. In this work, we have calculated and evaluated the lifetime of DESFAS by using Reliability Block Diagram (RBD) and failure rates of digital control components. Surveillance test is assumed in the evaluation. The result shows that the digital control component can be used in DESFAS system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.300-305
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• 2013

LOOP(Loss of Offsite Power) and SBO(Station Blackout) events have been occurring in nuclear power plants should be reviewed and be controlled on important electrical equipments by professional engineer to prevent and to safety improvement from safety assessment and reliability analysis report. LOOP and SBO occasionally happened by internal or external causes. This paper contained that LOOP frequency in the United States NPPs and in the domestic NPPs have compared and analyzed data by the past lessons and probabilistic statistics. Additionally will be installed MG(Mobile Generator) according to the lessons of Fukushima nuclear accident in Japan, which CDF(Core Damage Frequency) and LOOP frequency have reconsidered. And this paper proposed to reduce reliability criteria using PSA(Probabilistic Safety Analysis).

• 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.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.262-267
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• 2004

In designing and evaluating a new product, the company needs to give thought to the entire spectrum of produceability, usability, and ultimate reliability, as well as safety of users. For each design review(DR) stage, a formal, systematic, documented review and evaluation of a product design is conducted to assure that the product is safe and reliable, that costs and materials have been optimized, and that the design complies with its specifications and requirements. This paper presents how to improve development process for product's safety and reliability. The process requires gathering the appropriate information, determining the limits of the product, estimating risk associated with the task-hazard combinations, and reducing risk according to a prioritized procedure.

• Journal of the Korea Safety Management & Science
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• v.9 no.3
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• pp.15-19
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• 2007

This paper proposes a maintenance method to integrate worker's safety concerns into the process activities of the manufacturing system and it is to be considered as a part of the scope of maintenance engineering. The proposed method incorporates worker's health and safety considerations into maintenance engineering in each of the manufacturing process using reliability analysis. It can help to make a better planning and implementation of maintenance activities for the manufacturing system.