• Journal of Korean Society of Coastal and Ocean Engineers
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• 제19권5호
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• pp.399-407
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• 2007

Two reliability models, AFDA(Approximate Full Distribution Approach) and Monte-Carlo simulation method, are directly developed to study on both hydraulic failure mode of berm recession and structural failure mode of armour breakage of berm breakwaters. By comparing the present results with the results of other researcher, it may be confirmed that two reliability models can be straightforwardly applicable to berm breakwaters. Relative influence of each random variable on hydraulic and structural failure probabilities could be properly analyzed. The upper bound and the lower bound of failure probability can be evaluated by using bi-modal bounds of the multiple failure mode analysis, from which it may be possible to investigate some kinds of dependence into between two failure modes. Finally, it may also be found that the structural failure mode of armour breakage could become a main failure mode of berm breakwaters in the condition of more than any allowable berm recession.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제28권11호
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• pp.1813-1821
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• 2004

Until now, the 40% of wall thickness criterion, which is generally used for the plugging of steam generator tubes, has been applied only to a single cracked geometry. In the previous study by the authors, a total number of 9 local failure prediction models were introduced to estimate the coalescence load of two collinear through-wall cracks and, then, the reaction force model and plastic zone contact model were selected as the optimum ones. The objective of this study is to estimate the coalescence load of two collinear through-wall cracks in steam generator tube by using the optimum local failure prediction models. In order to investigate the applicability of the optimum local failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two collinear through-wall cracks in steam generator tube were carried out. Thereby, the applicability of the optimum local failure prediction models was verified and, finally, a coalescence evaluation diagram which can be used to determine whether the adjacent cracks detected by NDE coalesce or not has been developed.

• Journal of Internet Computing and Services
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• 제3권5호
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• pp.31-39
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• 2002

A rapid growth of internet and sudden increase of multimedia data demands for high-speed transfer media and if optimizec usage from the interface system. To achieve this level of network bandwidth, multiple NICs for support of high-speed network bandwidth have been developed and studied. Furthermore, the use of multiple NICs can provide high-speed LAN environment without large network environment modification, supports backward compatibility of current system and reduce overhead. However. if system failure is caused by SPOF(Single Point of Failure) fault of large-capacity multiple NICs, incredible loss will be met because it services large capacity of multimedia data, Therefore, to prevent loss coming from faults, we describe 'Fault tolerance of multiple NICs', which use the fault prevention mechanism. Considering inefficiency of availability and serviceability that is occurred with existing TMR, Primary-Standby approach and Watchdog time mechanism, we propose and design the efficient fault tolerance mechanism, which minimize down time as changing of detection period dynamically. Consequently, the fault tolerance mechanism proposed for reducing overhead time when the fault is occurred, should minimize system downtime overall.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제33권6호
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• pp.401-409
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• 2020

Seismic fragility assessments include a procedure to combine the random variables of response and capacity to produce the relationship between failure probability and seismic intensity. The evaluation of the failure probability of simultaneous multiple failures of two or more components assumes that the failure probability of each component is independent of those of the others. However, a correlation is expected to exist because several random factors have the same cause. The multiple-failure probability can differ depending on this correlation and may be unconservative without considering the seismic correlation. Therefore, a practical methodology for fragility assessment should be evaluated using the seismic correlation and correlation coefficient for each random variable. In this study, several random variables were selected for numerical evaluation of the correlation coefficient. The correlation coefficient was then compared with each variable and the combined variables. The correlation coefficient using simplified and complex models were also compared to determine and analyze the differences between each of the approaches.

• Journal of the Korean Society for Precision Engineering
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• 제15권11호
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• pp.218-226
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• 1998

In this study a neural network based expert system designed to diagnose operating status of a rotating spindle system supported by ball bearings was introduced. In order to facilitate practical failure situations, five exemplary abnormal status was fabricated. Out of several possible data source locations, seven most effective spots were chosen and proven to be the most successful in predicting single and multiple abnormalities. Increased signal strength was measured around where abnormality was embedded. Signal mea-surement locations producing high prediction rate were also classified. Even though multiple abnormalities were hard to be decoupled into their individual causes, proposed diagnostic system was somewhat effective in predicting such cases under certain combination of sensor locations. Among several abnormal operating conditions, highest prediction rate can be expected when signal is spoiled by the failure or damage in outer race. Proposed diagnostic system was again proven to be the most effective system in analyzing and ranking the importance of data sources.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제36권3호
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• pp.245-252
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• 2012

This paper proposes a simple numerical method, based on the stress-modified fracture strain-damage model with the stress-reduction technique, for predicting the failure behaviors of ductile plates with multiple through-wall cracks. This technique is implemented using the user-defined subroutines provided in ABAQUS. For validation, the results simulated using the proposed method are compared with published experimental data of Japanese researchers.

• Journal of the Korea Institute of Building Construction
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• 제4권2호
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• pp.137-142
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• 2004

There was the time of IMF(1998) that management condition of construction business had been the worst. After that time, structural regulation was completed and financial structure was returned to normalcy(2001). At that time, the aim of this paper is that fifteen construction business are researched for process of management condition and capital structure after they is selected as samples for three years, also failure of two-groups is predicted as statistics analysis and multiple discriminant analysis for them. In this paper, It is researched financial statement of business by the forecast experiment of failure and analyzed statistically possibility of failure and success for financial ratio. For them, the fifteen companies of failure and the fifteen companies what were not the failure, for listed company, and the fourteen variables are selected and they are analyzed statistically according to Logit Analysis.

• Journal of Advanced Navigation Technology
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• 제16권4호
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• pp.593-601
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• 2012

This paper develops and analyzes a new multiple-hypothesis Receiver Autonomous Integrity Monitoring (RAIM) algorithm as a candidate for future standard architecture. The proposed algorithm can handle simultaneous multiple failures as well as a single failure. It uses measurement residuals and satellite observation matrices of several consecutive epochs for Failure Detection and Exclusion (FDE). The proposed algorithm redueces the Minimum Detectable Bias (MDB) via the Relative RAIM (RRAIM) scheme. Simulation results show that the proposed algorithm can detect and filter out multiple failures in tens of meters.

• Journal of Chest Surgery
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• 제22권6호
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• pp.970-979
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• 1989

From April 1982 to December, 1988, multiple valve replacement was performed in 49 patients. Mitral and aortic valve replacement were done in 42 patients, 4 underwent mitral and tricuspid valve replacement and 3 patients underwent triple valve replacement. Of the valve implanted, 50 were Duromedics, 21 St. Jude, 13 Bjork-Shiley, 9 Carpentier-Edwards, 6 Ionescu-Shiley, and 2 Medtronic. The hospital mortality rate was 28.5 % [14 patients] and the late mortality rate was 6.1 % [3 patients], the mortality rate was high in early operative period but decreased with time. [20% at 1986, 18.2 % at 1987, 9.5% at 1988] The causes of death were low cardiac output in 8, congestive heart failure in 2, multiple organ failure in 1, LV rupture in 1, intracerebral hemorrhage in 1 and sudden death in l. The actuarial survival rate excluding operative death was 77% at 7 years.

• Journal of the Korea Concrete Institute
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• 제16권3호
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• pp.345-356
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• 2004

A plasticity model was developed to predict the behavioral characteristics of concrete in multiaxial compression. To extend the applicability of the proposed model to concrete in various stress states, a new approach for failure criteria was attempted. A stress was decomposed into one volumetric and two deviatoric components orthogonal to each other. Three failure criteria wire provided independently for each stress component. To satisfy the three failure criteria, the plasticity model using multiple failure criteria was Implemented. Each failure surface was defined by equivalent volumetric or deviatoric plastic strain. To present dilatancy due to compressive damage a non-associative flow nile was proposed. The proposed model was implemented to finite element analysis, and it was verified by comparisons with various existing test results. The comparisons show that the proposed model predicted well most of the experiments by using three independent failure criteria.