• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.329-335
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• 2016

In the present paper, Computational fluid dynamics (CFD) uncertainty analysis proposed by ITTC was investigated and applied to ship resistance performance using open source libraries, called OpenFOAM. Uncertainties for grid size, time step and iteration number were studied. Wave patterns and hull wave profile were compared for various uncertainty parameters. From results, grid size uncertainty was mainly contributed to simulation numerical uncertainty.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.40-45
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• 2010

Evaluation of uncertainty is an ongoing process that can consume time and resources. It can also require the service of someone who is familiar with data analysis techniques. Therefore, it is important for laboratory personnel who are approaching uncertainty analysis for the first time to be aware of the resources required. International inclination of measurement filed to guarantee the traceability and confidence of measurement results discards the error concept and instead analyzes the measurement uncertainty. In this paper, we analyzed the elements of measurement uncertainty on surface roughness test which are the important things in mechanical parts test. Repeat the test by 3 men, the measurement uncertainty could be calculated.

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.577-591
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• 2022

This paper develops a comparatively time-efficient methodology for performing seismic fragility analysis of the reinforced concrete (RC) buildings in the presence of uncertainty sources. It aims to appraise the effectiveness of any variation in the material's mechanical properties as epistemic uncertainty, and the record-to-record variation as aleatory uncertainty in structural response. In this respect, the fuzzy set theory, a well-known 𝛼-cut approach, and the Genetic Algorithm (GA) assess the median of collapse fragility curves as a fuzzy response. GA is requisite for searching the maxima and minima of the objective function (median fragility herein) in each membership degree, 𝛼. As this is a complicated and time-consuming process, the authors propose utilizing the Gene Expression Programming-based (GEP-based) equation for reducing the computational analysis time of the case study building significantly. The results indicate that the proposed structural analysis algorithm on the derived GEP model is able to compute the fuzzy median fragility about 33.3% faster, with errors less than 1%.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.484-497
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• 2021

This paper proposes an extended time uncertainty analysis approach in Level 2 human reliability analysis (HRA) considering severe accident management (SAM) strategies. The method is a time-based model that classifies two time distribution functions-time required and time available-to calculate human failure probabilities from delayed action when implementing SAM strategies. The time required function can be obtained by the combination of four time factors: 1) time for diagnosis and decision by the technical support center (TSC) for a given strategy, 2) time for strategy implementation mainly by the local emergency response organization (ERO), 3) time to verify the effectiveness of the strategy and 4) time for portable equipment transport and installation. This function can vary depending on the given scenario and includes a summation of lognormal distributions and a choice regarding shifting the distribution. The time available function can be obtained via thermal-hydraulic code simulation (MAAP 5.03). The proposed approach was applied to assess SAM strategies that use portable equipment and safety depressurization system valves in a total loss of component cooling water event that could cause reactor vessel failure. The results from the proposed method are more realistic (i.e., not conservative) than other existing methods in evaluating SAM strategies involving the use of portable equipment.

• Journal of Korean Academy of Nursing
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• v.47 no.4
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• pp.499-513
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• 2017

Purpose: This concept analysis was done to clarify 'uncertainty in epilepsy'. Methods: Walker and Avant's methodology guided the analysis. In addition, the concept was compared with uncertainty in other health problems. Results: 'Uncertainty in epilepsy' was defined as being in the condition as seen from the epilepsy experience where cues were difficult to understand because they changed, were in discord with past ones, or they had two or more contradictory values at the same time. Uncertainty in epilepsy is evolved from appraisal of the epilepsy experience. As a result, uncertainty leads epilepsy patients, their family or health care providers to impaired functioning and proactive/passive coping behavior. Conclusion: Epilepsy patients with uncertainty need to be supported by nursing strategies for proactive, rational coping behavior. This achievement has implications for interventions aimed at changing perception of epilepsy patients, their families or health care providers who must deal with uncertainty.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.378-386
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• 2002

Multi-path ultrasonic Sow measurement system uncertainty is determined by assigning an expected error of each component of flow measurement and then defining the total flow measurement uncertainty as square root of the sum of squared values of the individual error. Sources of uncertainty for flow measurement are geometry, transit time and velocity profile integration uncertainty. A theoretical uncertainty model for multi-path ultrasonic transit time flowmeter configured with parallel 5 chords, is derived from and calculated by dry calibration method.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.163-168
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• 2017

This paper presented an evaluation method for the efficiency uncertainty of a three-phase induction motor using finite element analysis. The motor efficiency in the finite element analysis is calculated by the loss separation method as in the actual test. In the process of evaluating the efficiency uncertainty, the difference between the finite element analysis and the actual test is the method of calculating the type-A / B standard uncertainty of the input quantity to estimate the efficiency and each losses. For the input quantities which can confirm the instantaneous values with respect to time, the type-A standard uncertainty in the finite element analysis is calculated from the RMS values or average values having separate periods in the steady state. And, the type-B standard uncertainty in the finite element analysis is assumed to be zero. Also, this paper compared and analyzed the efficiency uncertainty evaluated by the proposed method and the efficiency uncertainty through the actual test.

• Journal of the Korean Society for information Management
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• v.36 no.2
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• pp.175-199
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• 2019

Uncertainty means incomplete stages of knowledge of propositions due to the lack of consensus of information and existing knowledge. As the amount of academic literature increases exponentially over time, new knowledge is discovered as research develops. Although the flow of time may be an important factor to identify patterns of uncertainty in scientific knowledge, existing studies have only identified the nature of uncertainty based on the frequency in a particular discipline, and they did not take into consideration of the flow of time. Therefore, in this study, we identify and analyze the uncertainty words that indicate uncertainty in the scientific literature and investigate the stream of knowledge. We examine the pattern of biomedical knowledge such as representative entity pairs, predicate types, and entities over time. We also perform the significance testing using linear regression analysis. Seven pairs out of 17 entity pairs show the significant decrease pattern statistically and all 10 representative predicates decrease significantly over time. We analyze the relative importance of representative entities by year and identify entities that display a significant rising and falling pattern.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.462-465
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• 2006

This paper is aimed at proposing the sampling method to reduce variance of statistical parameters in uncertainty analysis of concrete structures. The proposed method is a modification of Latin Hypercube sampling method. This uses specially modified tables of random permutations of rank number. Also, the Spearman coefficient is used to make modified tables. Numerical analysis is carried out to predict the uncertainty of axial shortening in prestressed concrete bridge. The numerical results show that the method is efficient for uncertainty analysis of complex structural system such as prestressed concrete bridges.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2670-2677
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• 2023

In the nuclear safety studies, a new trend refers to the evaluation of uncertainties as a mandatory component of best-estimate safety analysis which is a modern and technically consistent approach being known as BEPU (Best Estimate Plus Uncertainty). The major objectives of this study consist in performing a study of uncertainties/sensitivities of the major analysis results for a generic CANDU 6 Nuclear Power Plant during Station Blackout (SBO) progression to understand and characterize the sources of uncertainties and their effects on the key figure-of-merits (FOMs) predictions in severe accidents (SA). The FOMs of interest are hydrogen mass generation and event timings such as the first fuel channel failure time, beginning of the core disassembly time, core collapse time and calandria vessel failure time. The outcomes of the study, will allow an improvement of capabilities and expertise to perform uncertainty and sensitivity analysis with severe accident codes for CANDU 6 Nuclear Power Plant.