• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.55-63
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• 2015

Post-installed concrete set anchors are installed after the concrete hardened. These anchors increasing usage in development of construction equipment and flexible construction. The anchor loaded in shearing exhibits various failure modes such as steel failure, concrete failure, concrete pryout, depending on the shear strength of steel, the strength of concrete, edge distance and anchor interval, etc,. In this study, the objective is to investigate the effects of the variations like anchor embedment depth, edge distance and concrete strength on experimental and finite element analysis of shear failure behavior of post-installed concrete set anchor for light load embedded in concrete. The results of embedment depth experiments show that concrete strength has much affection on the shallow embedment depth. Concrete strength has no much affection with anchor interval and edge distance parameter and both experimental results occurred same failure mode. By comparing the experimental results that occurred steel failure mode show that as strong as concrete strength are the displacement results are small.

• Proceedings of the Korean Society for Quality Management Conference
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• 2009.10a
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• pp.227-229
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• 2009

Recent discussions in the active growth strategy based on getting a green environment, changes in the management of companies involved in environmental management is the analysis of various risk factors and the green growth at the same time the company's growth strategy is required. Thus, the corporate position on the green growth strategy based on risk management to analyze and respond to face reality, and respond to the scene of the applied methodology is required. In this study, contact the section of Environment to assess potential business risks that the EMEA Environment Mode Effects Analysis methodology through research and development company's in, contact the section of Environment to effectively analyze risk management by addressing the degree of risk assessment as a future-oriented and objective can manage is to provide technical management model.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.36-47
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• 2010

The Korean Railroad Research Institute (KRRI) has developed the rubber tired AGT system (Model: K-AGT) between 1999 and 2005. The K-AGT is a light rail transit system does not require a driver and generally operates on an elevated railroad for transporting passengers. Accidents caused by driverless vehicles can severely affect social confidence, safety and economy therefore, it is very important to minimize the occurrences of such faults, and to accurately perform detailed maintenance tasks and thoroughly investigate the cause of any repeated failures. This research develops the web-based Preventive Maintenance (PM) system for the KAGT train system. The framework of the PM system is based on performing a reliability analysis and a failure mode effects analyses (FMEA) procedure on all the sub-systems in the K-AGT system. Out of the devices that have a low reliability, the high failure ranked devices are included high in the list for performing the overall maintenance plans. Through registration of historical failure data, the reliability indexes can be updated. Such a process is repeated continuously and can achieve very accurate predictions for device operational life times and failure rates. Therefore, this research describes the development of the overall PM system consists of a reliability analysis module, a failure mode effect analysis module, and maintenance request module.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.7-13
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• 2011

Turbine journal bearings are designed to support the weight of the rotors on a hydrodynamic oil film and to provide dynamic stability to the rotor system. The life time of journal bearings is infinite theoretically because the journal bearings are separated from the shaft journal by oil film. But poor design, assembly, operation and maintenance can cause problems to the journal bearings. The FMEA(Failure Mode and Effects Analysis) results of the journal bearings show that frequent maintenance of the journal bearings can cause failures and reduction of the bearing life. Therefore, the maintenance periods and history of the journal bearings with the bearing FMEA results are reviewed in order to establish the optimized maintenance period of the journal bearing for the nuclear power plants. Consequently it is necessary to maintain a best condition of lubrication system, reject time-based maintenance and perform the condition-based maintenance of journal bearings in order to maintain optimum condition of the journal bearing.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.621-630
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• 2018

In the note a comprehensive and optimal passive-active mode for describing the limit failure of circular shallow tunnel with settlement is put forward to predict the catastrophic stability during the geotechnical construction. Since the surrounding soil mass around tunnel roof is not homogeneous, with tools of variation calculus, several different curve functions which depict several failure shapes in different soil layers are obtained using virtual work formulae. By making reference to the simple-form of Power-law failure criteria based on numerous experiments, a numerical procedure with consideration of combination of upper bound theorem and stochastic medium theory is applied to the optimal analysis of shallow-buried tunnel failure. With help of functional catastrophe theory, this work presented a more accurate and optimal failure profile compared with previous work. Lastly the note discusses different effects of parameters in new yield rule and soil mechanical coefficients on failure mechanisms. The scope of failure block becomes smaller with increase of the parameter A and the range of failure soil mass tends to decrease with decrease of unit weight of the soil and tunnel radius, which verifies the geomechanics and practical case in engineering.

• IE interfaces
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• v.25 no.4
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• pp.422-430
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• 2012

In this article, we introduced the estimation method by 'Safety Integrity Level'(SIL) for the criterion of safety assurance and performed a case study on a flame scanner. SIL requires probabilistic evaluation of each set of equipment used to reduce risk in a safety related system. FMEDA(Failure Modes, Effects and Diagnostic Analysis) method is widely used to evaluate the safety levels and provides information on the failure rates and failure mode distributions necessary to calculate a diagnostic coverage factor for a part or a component. Basically, two parameters resulting from FMEDA are used for SIL classification of the device : SFF(Safe Failure Fraction) and PFD(Probability of Failure on Demand). In this case study, it is concluded that the flame scanner is designed to fulfill the condition of SIL 3 in the aspect of SFF and PFD.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.2
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• pp.1-7
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• 2005

For the reliability evaluation of the track drive unit(TDU), firstly, we analyzed the major failure modes through FMEA(failure mode & effects analysis), FTA(failure tree analysis), and 2-stage QFD(quality function deployment), and then quantitatively determined the priority order of test items. The Minitab analysis was also performed for prediction of life distribution and parameters of TDU by use of field failure data collected from 430 excavators for two years. In addition, we converted the fluctuation load in field conditions into the equivalent load, and for evaluation of the accelerated lift by the cumulative fatigues, the equivalent load is again divided into the fluctuation load by reference of test time. And then, by use of the test method in this paper, the acceleration factor(AF) of needle bearing inside planetary gear which is the most weakly designed part of TDU is achieved as 5.3. This paper presents the quantitative selection method of test items for reliability evaluation, the determination method of the accelerated life test time, and the method of non-failure test time based on a few of samples. And, we proved the propriety of the proposed methods by experiments using a TDU for a 30 ton excavator.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.342-347
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• 2009

Failure Mode Effects and Criticality Analysis (FMECA) is one of most widely used methods in modern engineering system to investigate potential failure modes and its severity upon the system. While performing FMECA, the experts evaluates criticality and severity of each failure mode and visualize the risk level matrix putting those indices to column and row variable respectably. Which results uncertainty in the result. In order to handle the uncertainty and conclude risk level matrix, this paper proposes a new FMECA procedure using minimal cut set (MCS) and fuzzy theory. Severity is calculated by proposed structural importance while criticality is determined by typical equipment failure rate data from IEEE Std 493. Finally, the risk level is compounded of these indices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.69-76
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• 2017

In this study, design of a small hybrid rocket is carried out using Failure Mode and Effects Analysis (FMEA) and Criticality Analysis(CA), which is a method for qualitative and semi-quantitative reliability analysis. In order to carry out FMEA, the structure of the hybrid rocket is divided into 31 parts and 72 potential failure modes. As a result of the FMEA, the relationship between potential failure modes, causes and effects, and their severity are evaluated qualitatively. Criticality analysis is followed for the failure modes, in which the criticality number is estimated using the failure rate information available from the handbook. Moreover, the failure modes with higher criticality and severity are chosen for improvement, and a series of design or material changes are made for the improvement of the hybrid rocket reliability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.751-758
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• 2021

Munitions must be analyzed to identify any risks for quality assurance in development and mass production. Risk identification for parts, compositions, and systems is carried out through failure mode effects analysis (FMEA) as one of the most reliable methods. FMEA is a design tool for the failure mode of risk identification and relies on the RPN (risk priority number). FMEA has disadvantages because its severity, occurrence, and detectability are rated at the same level. Fuzzy FMEA applies fuzzy logic to compensate for the shortcomings of FMEA. The fuzzy logic of Fuzzy FMEA is to express uncertainties about the phenomenon and provides quantitative values. In this paper, Fuzzy FMEA is applied to the failure mode of a rotorcraft landing system. The Fuzzy rule and membership functions were conducted in the Fuzzy model to study the RPN in the failure mode of a landing system. This method was selected to demonstrate crisp values of severity, occurrence, and detectability. In addition, the RPN was obtained. The results of Fuzzy FMEA for the landing system were analyzed for the RPN and ranking by fuzzy logic. Finally, Fuzzy FMEA confirmed that it could use the data in quality assurance activities for rotorcraft.