• Title/Summary/Keyword: technology reliability

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Evaluation of Partial Safety Factors of Armor Units by Inverse-Reliability Analysis (역해석법에 의한 피복재의 부분안전계수 산정)

  • Lee, Cheol-Eung;Park, Dong-Heon
    • Journal of Industrial Technology
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    • v.28 no.B
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    • pp.149-156
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    • 2008
  • A reliability model of Level II AFDA is developed to analyze the stability of armor units on the sloped coastal structures. Additionally, the partial safety factors of random variables related to armor units can be straightforwardly evaluated by applying the inverse-reliability method in which influence coefficients and uncertainties of random variables, and target probability of failure are combined directly. In particular, a design equation for armor units is derived in terms of the same criteria as deterministic design method in order to apply the reliability-based design method of Level I without some understanding to the reliability analysis. Finally, it is confirmed that several results redesigned by the reliability-based design method of Level I have satisfactorily agreement with results of CEM as well as those of Level II AFDA.

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Embodying RBD and Reliability Analysis Technology base on Web (웹 기반 RBD 구현 및 신뢰도 평가기술)

  • 송준엽;이승우;이후상;조복기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1541-1544
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    • 2003
  • In this study, embodying reliability block diagram based on the web and reliability analysis technology are developed. RBD(reliability Block Diagram) represents the functional relation between elements in any product. Among relations between elements. there are serial, parallel, bridge, and stand by, etc. Advantages of developed system are integrated datum about reliability (NPRD, EPRD, MIL-HDBK 217F, NSWC. OREDA. Bellcore, and domestic institutes & companies datum). graphic user interface for convenience, and the various service analyzes the failure history data of parts.

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Reliability Assessment Criteria of Rigid Multi-layer PCB for RAM (RAM용 경질다층 PCB의 신뢰성 평가기준)

  • Hong, Won-Sik;Song, Byeong-Suk;Baik, Jai-Wook;Jeong, Hai-Sung
    • Journal of Applied Reliability
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    • v.9 no.3
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    • pp.259-274
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    • 2009
  • Printed circuit boards for RAM are widely used in modern electronics such as computers, artificial satellites and consumer durables. They are exposed to a very diverse environment and consists of many complicated components and therefore needs careful approach to the enhancement and assessment of reliability of the item. In this article reliability standards for PCBs for RAM are established in terms of quality certification tests and failure rate tests.

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Fuzzy reliability analysis of laminated composites

  • Chen, Jianqiao;Wei, Junhong;Xu, Yurong
    • Structural Engineering and Mechanics
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    • v.22 no.6
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    • pp.665-683
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    • 2006
  • The strength behaviors of Fiber Reinforced Plastics (FRP) Composites can be greatly influenced by the properties of constitutive materials, the laminate structures, and load conditions etc, accompanied by many uncertainty factors. So the reliability study on FRP is an important subject of research. Many achievements have been made in reliability studies based on the probability theory, but little has been done on the roles played by fuzzy variables. In this paper, a fuzzy reliability model for FRP laminates is established first, in which the loads are considered as random variables and the strengths as fuzzy variables. Then a numerical model is developed to assess the fuzzy reliability. The Monte Carlo simulation method is utilized to compute the reliability of laminas under the maximum stress criterion. In the second part of this paper, a generalized fuzzy reliability model (GFRM) is proposed. By virtue of the fact that there may exist a series of states between the failure state and the function state, a fuzzy assumption for the structure state together with the probabilistic assumption for strength parameters is adopted to construct the GFRM of composite materials. By defining a generalized limit state function, the problem is converted to the conventional reliability formula that enables the first-order reliability method (FORM) applicable in calculating the reliability index. Several examples are worked out to show the validity of the models and the efficiency of the methods proposed in this paper. The parameter sensitivity analysis shows that some of the mean values of the strength parameters have great influence on the laminated composites' reliability. The differences resulting from the application of different failure criteria and different fuzzy assumptions are also discussed. It is concluded that the GFRM is feasible to use, and can provide an effective and synthetic method to evaluate the reliability of a system with different types of uncertainty factors.

Multivariate analysis of critical parameters influencing the reliability of thermal-hydraulic passive safety system

  • Olatubosun, Samuel Abiodun;Zhang, Zhijian
    • Nuclear Engineering and Technology
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    • v.51 no.1
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    • pp.45-53
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    • 2019
  • Thermal-hydraulic passive safety systems (PSSs) are incorporated into many advanced reactor designs on the bases of simplicity, economics and inherent safety nature. Several factors among which are the critical parameters (CPs) that influence failure and reliability of thermal-hydraulic (t-h) passive systems are now being explored. For simplicity, it is assumed in most reliability analyses that the CPs are independent whereas in practice this assumption is not always valid. There is need to critically examine the dependency influence of the CPs on reliability of the t-h passive systems at design stage and in operation to guarantee safety/better performance. In this paper, two multivariate analysis methods (covariance and conditional subjective probability density function) were presented and applied to a simple PSS. The methods followed a generalized procedure for evaluating t-h reliability based on dependency consideration. A passively water-cooled steam generator was used to demonstrate the dependency of the identified key CPs using the methods. The results obtained from the methods are in agreement and justified the need to consider the dependency of CPs in t-h reliability. For dependable t-h reliability, it is advisable to adopt all possible CPs and apply suitable multivariate method in dependency consideration of CPs among other factors.

RELIABILITY IN DESIGN AND DEVELOPMENT

  • Murthy, D.N.P.
    • Proceedings of the Korean Reliability Society Conference
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    • 2004.04a
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    • pp.69-79
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    • 2004
  • Joint program with the Norwegian University of Science and Technology, Trondheim, Norway.(omitted)

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Reliability Assessment Criteria of Motorized Roller Conveyor (자체구동롤러 컨베이어의 신뢰성 평가기준)

  • Kim, Young-Joo;Go, Hee-Yang;Han, In-Sup;Kim, Yong Soo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.5
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    • pp.521-529
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    • 2015
  • Owing to a reliance on imported products from Europe and Japan, the use of logistics equipment with poor energy efficiency coupled with high maintenance costs can lead to high operating costs for some domestic logistic centers. To lower their operating costs, the logistic centers use motorized roller conveyors. In order to commercialize this process, it is necessary to establish the test criteria and assess the reliability of the process. Currently, there exists no standard verification method to test the reliability of motorized roller conveyors. In this study, we propose reliability assessment criteria for a: i) reliability test, ii) environmental test, iii) safety test, and iv) lifetime test.

Accelerated Test Design for Crankshaft Reliability Estimation

  • Jung, D.H.;Pyun, Y.S.;Gafurov, A.;Chung, W.S.
    • International Journal of Reliability and Applications
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    • v.10 no.2
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    • pp.109-118
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    • 2009
  • Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending and torsion fatigue limits of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending and torsion tests of the original crankshaft are carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the $B_{10}$ life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid.

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