• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.565-578
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• 2016

A probabilistic based systems approach is addressed in this study for the reliability prediction of solid rocket motors (SRM). To achieve this goal, quantitative Failure Modes, Effects and Criticality Analysis (FMECA) approach is employed to determine the reliability of components, which are integrated into the Fault Tree Analysis (FTA) to obtain the system reliability. The quantitative FMECA is implemented by burden and capability approach when they are available. Otherwise, the semi-quantitative FMECA is taken using the failure rate handbook. Among the many failure modes in the SRM, four most important problems are chosen to illustrate the burden and capability approach, which are the rupture, fracture of the case, and leak due to the jointed bolt and O-ring seal failure. Four algorithms are employed to determine the failure probability of these problems, and compared with those by the Monte Carlo Simulation as well as the commercial code NESSUS for verification. Overall, the study offers a comprehensive treatment of the reliability practice for the SRM development, and may be useful across the wide range of propulsion systems in the aerospace community.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.248-254
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• 2008

Electric railway system consists of traction power system, rolling stock, track, and overhead line system. A railway substation transforms the electric power transmitted from a electric power company and supply it to the railway power system for the operation of traction system.. It is very important to prevent a possible accident and keep the security of electric power system. This paper proposes a reliability analysis of AC railway substation by using Fault Tree Analysis(FTA). Failure rates of each equipment of railway substation are used to evaluate the reliability of railway substation. The analyzed results can be used to improve the system reliability. FTA is performed by the commercialized program of Relex(Ver. 7.7).

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.964-967
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• 2013

현재에 시스템의 결함을 분석하는 안전성 분석 기법들이 여러 가지가 있다. 본 논문에서는 많은 결함 분석 기법 중에서 FTA(Fault Tree Analysis)와 FMECA(Failure Modes, Effect and Criticality Analysis)을 통하여 안전성 분석을 하고자 한다. 또한 이 두 가지 기법을 따로 사용하지 않고 전방에서 FTA 분석을 하고 후방에서 FMECA 분석을 수행하는 통합 기법을 제안한다. 이를 통해 각 기법의 단점을 최소화하고 장점을 최대화 하여 안전성 분석의 효율성을 제고하고자 한다.

• 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 Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.325-329
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• 1992

The development of automatic production system have required intelligent diagnostic and monitoring function to repair system failure and reduce production loss by the failure. In order to perform accurate functions of intelligent system, inference about total system failure and fault analysis due to each mechanical component failures are required. Also the solution about repair and maintenance can be suggested from these analysis results. Generally, bearing is a essential mechanical component in the machinery. The bearing failure is caused by lubricant system failure, metallurgical defficiency, mechanical condition(vibration overloading misalignment), environmental effect. This study described roller bearing fault train due to stress variation and metallurgical defficiency from lubricant failure by using FTA.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.43-55
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• 2012

Bicycle is an environment-friendly transport mode contributing to a more sustainable transportation systems. To innovatively increase the use of bicycle as a significant transport mode, bicycle-friendly roadway environment should be provided. This study proposes a method to evaluate cycling environment based on the analysis of data collected from an specially equipped probe bicycle. The inertial measurement unit(IMU) consisting of a gyro sensor, accelerometer, and a global positioning systems(GPS) receiver was installed on the probe bicycle. Cycling stability index(CSI) and bicycle speed data were used as inputs of the proposed evaluation framework adopting the Fault Tree Analysis, which is a well-known technique for the risk analysis. The outcomes of this study will serve as an intelligent assesment tool for cycling environment.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.192-198
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• 2015

Fault Tree Analysis to predict the lifetime in the design process of LNG compressor is considered. Fault Trees for P & ID of the compressor are created. Individual components that comprise the compressor are configured with the basic event. The failure rates in the PDS and OREDA are applied. As results, the system failure rate and the reliability over time are obtained. Further, the power transmission and the shaft seal system is confirmed to confidentially importantly contribute to the overall lifetime of the system. These techniques will help to improve the reliability of design of large scale machinery such as a plant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.9-17
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• 2017

Ensuring the safety of automobiles and trains during system operation is regarded as indispensable due to the progress in unmanned operation. The automotive functional safety standard, ISO 26262, has been proposed to ensure the safe design of vehicles. This standard describes in detail the required risk analysis and evaluation procedure and safety measures, while appropriately reflecting the system design information. Therefore, much research has been done on the risk analysis procedure, wherein the design information is mostly extracted from physical components of similar systems already in operation, the information traced back to obtain constituent functions, and then methods of identifying risk sources are studied. This method allows the sources of risk to be identified quickly and easily, however if the design requirements are changed or systems are newly developed, others may be introduced which are not accounted for, thereby yielding mismatched design information. To resolve this problem, we propose a top-down analysis in order to utilize the system design information appropriately. Specifically, a conceptual system is designed to obtain the functions, which are then analyzed. Then, a function-based fault tree analysis is conducted, followed by a risk source analysis. In this paper, a case study of automotive safety is presented, revealing that the proposed method can analyze the risk sources with reduced possibility of omission by systematically reflecting the system design information.

• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.127-132
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• 1997

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.21-25
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• 2013

The system and components for aircraft are required the design data on which the safety requirements are properly reflected for their certification. This paper presents the procedure and results of a safety assessments analysis for the rotorcraft fuel pumps in oder to confirm and verify them. The fuel pumps design assessment must be performed, including a detailed failure analysis to identify all failures that will prevent continued safe flight or safe landing. In order to assess the fuel pumps design safety, not only system safety hazard analysis and but FTA(Fault Tree Analysis) for proofing the safety objective of the fuel pumps are performed. The results of the safety assessment for fuel pumps validate that no single failure or malfunction could result in catastrophic failure or critical accidents of the rotorcraft.