• Title, Summary, Keyword: Uncertainty analysis

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Uncertainty Study of Added Resistance Experiment (부가저항 실험의 불확실성 연구)

  • Park, Dong-Min;Lee, Jaehoon;Kim, Yonghwan
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.5
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    • pp.396-408
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    • 2014
  • In this study, uncertainty analysis based on ITTC(International Towing Tank Conference) Recommended Procedures is carried out in the towing-tank experiment for motion responses and added resistance. The experiment was conducted for KVLCC2 model in head sea condition. The heave, pitch and added resistance were measured in different wave conditions, and the measurement was repeated up to maximum 15 times in each wave condition in order to observe the uncertainty of measured data. The uncertainty analysis was carried out by adopting the ISO-GUM(International Organization for Standardization, Guide to the Expression of Uncertainty in Measurements) method recommended by ITTC. This paper describes the details about the analysis method, uncertainty and the measured uncertainty for each source. The uncertainty analysis results are summarized as a tabular form. To validate the accuracy of the present measurement, the experimental results are compared with the results of numerical computation and other experiment. From the present uncertainty analysis, the main sources of uncertainty are identified, which can be very useful to improve the accuracy for added resistance experiment.

Analysis of Structural Reliability under Model and Statistical Uncertainties: a Bayesian Approach

  • Kiureghian, Armen-Der
    • Computational Structural Engineering : An International Journal
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    • v.1 no.2
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    • pp.81-87
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    • 2001
  • A framework for reliability analysis of structural components and systems under conditions of statistical and model uncertainty is presented. The Bayesian parameter estimation method is used to derive the posterior distribution of model parameters reflecting epistemic uncertainties. Point, predictive and bound estimates of reliability accounting for parameter uncertainties are derived. The bounds estimates explicitly reflect the effect of epistemic uncertainties on the reliability measure. These developments are enhance-ments of second-moment uncertainty analysis methods developed by A. H-S. Ang and others three decades ago.

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SAMPLING BASED UNCERTAINTY ANALYSIS OF 10 % HOT LEG BREAK LOCA IN LARGE SCALE TEST FACILITY

  • Sengupta, Samiran;Dubey, S.K.;Rao, R.S.;Gupta, S.K.;Raina, V.K
    • Nuclear Engineering and Technology
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    • v.42 no.6
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    • pp.690-703
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    • 2010
  • Sampling based uncertainty analysis was carried out to quantify uncertainty in predictions of best estimate code RELAP5/MOD3.2 for a thermal hydraulic test (10% hot leg break LOCA) performed in the Large Scale Test Facility (LSTF) as a part of an IAEA coordinated research project. The nodalisation of the test facility was qualified for both steady state and transient level by systematically applying the procedures led by uncertainty methodology based on accuracy extrapolation (UMAE); uncertainty analysis was carried out using the Latin hypercube sampling (LHS) method to evaluate uncertainty for ten input parameters. Sixteen output parameters were selected for uncertainty evaluation and uncertainty band between $5^{th}$ and $95^{th}$ percentile of the output parameters were evaluated. It was observed that the uncertainty band for the primary pressure during two phase blowdown is larger than that of the remaining period. Similarly, a larger uncertainty band is observed relating to accumulator injection flow during reflood phase. Importance analysis was also carried out and standard rank regression coefficients were computed to quantify the effect of each individual input parameter on output parameters. It was observed that the break discharge coefficient is the most important uncertain parameter relating to the prediction of all the primary side parameters and that the steam generator (SG) relief pressure setting is the most important parameter in predicting the SG secondary pressure.

Evaluation of Efficiency Uncertainty for Three-phase Induction Motor using Finite Element Analysis (유한요소 해석을 이용한 3상 유도전동기의 효율 불확도 평가)

  • Lee, Ho-Hyun;Park, Han-Seok;Jun, Hee-Deuk;Woo, Kyung-Il
    • 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.

Uncertainty Evaluation of Ammonia Determination in Burley Tobacco (버어리종 담배중 암모니아성 질소에 대한 불확도 측정)

  • Lee Jeong-Min;Lee Kyoung-Ku;Han Sang-Bin
    • Journal of the Korean Society of Tobacco Science
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    • v.27 no.1
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    • pp.107-114
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    • 2005
  • The uncertainty of measurement in quantitative analysis of ammonia by continuous-flow analysis method was evaluated following internationally accepted guidelines. The sources of uncertainty associated with the analysis of ammonia were the weighing of sample, the preparation of extracting solution, the addition of extracting solution into the sample, the reproducibility of analysis and the determination of water content in tobacco, etc. In calculating uncertainties, Type A of uncertainty was evaluated by the statistical analysis of a series of observation, and Type B by the information based on supplier's catalogue and/or certificated of calibration. It was shown that the main source of uncertainty was caused by the volume measurement of 1 mL and 2 mL, the purity of ammonia reference material in the preparation of standard solution, the reproducibility of analysis and the determination of water content of tobacco. The uncertainty in the addition of extraction solution, the sample weighing, the volume measurement of 50 mL and 100 mL, and the calibration curve of standard solution contributed relatively little to the overall uncertainty. The expanded uncertainty of ammonia determination in burley tobacco at $95\%$ level of confidence was $0.00997\%$.

A Correlational Study on Uncertainty, Mastery and Appraisal of Uncertainty in Hospitalized Children's Mothers (입원 아동 어머니가 지각하는 불확실성, 극복력 및 불확실성 인지의 관계)

  • Yoo, Kyung-Hee
    • Journal of Korean Academy of Nursing
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    • v.37 no.4
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    • pp.594-602
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    • 2007
  • Purpose: This study was conducted to investigate the correlation among uncertainty, mastery and appraisal of uncertainty in hospitalized children's mothers. Method: Self report questionnaires were used to measure the variables Variables were uncertainty, mastery and appraisal of uncertainty. In data analysis, the SPSSWIN 12.0 program was utilized for descriptive statistics, Pearson's correlation coefficients, and regression analysis. Result: Reliability of the instruments was cronbach's $alpha=.84{\sim}.94$. Mastery negatively correlated with uncertainty(r=-.444, p=.000) and danger appraisal of uncertainty(r=-.514, p=.000). In regression of danger appraisal of uncertainty, uncertainty and mastery were significant predictors explaining 39.9%. Conclusion: Mastery was a significant mediating factor between uncertainty and danger appraisal of uncertainty in hospitalized children's mothers. Therefore, nursing interventions which improve mastery must be developed for hospitalized children's mothers.

Uncertainty Analysis for Parameter Estimation of Probability Distribution in Rainfall Frequency Analysis Using Bootstrap (강우빈도해석에서 Bootstrap을 이용한 확률분포의 매개변수 추정에 대한 불확실성 해석)

  • Seo, Young-Min;Park, Ki-Bum
    • Journal of Environmental Science International
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    • v.20 no.3
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    • pp.321-327
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    • 2011
  • Bootstrap methods is the computer-based resampling method that estimates the standard errors and confidence intervals of summary statistics using the plug-in principle for assessing the accuracy or uncertainty of statistical estimates, and the BCa method among the Bootstrap methods is known much superior to other Bootstrap methods in respect of the standards of statistical validation. Therefore this study suggests the method of the representation and treatment of uncertainty in flood risk assessment and water resources planning from the construction and application of rainfall frequency analysis model considersing the uncertainty based on the nonparametric BCa method among the Bootstrap methods for the assessement of the estimation of probability rainfall and the effect of uncertainty considering the uncertainty of the parameter estimation of probability in the rainfall frequency analysis that is the most fundamental in flood risk assessement and water resources planning.

A Concept Analysis of Uncertainty in Epilepsy (뇌전증 환자의 불확실성 개념분석)

  • Lee, Juna;Lee, Insook
    • 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.

Uncertainty of Measurement in Nitrate Analysis from Burley Leaf Tobacco (버어리종 담배 중 질산성 질소에 대한 측정불확도)

  • Lee Jeong-Min;Lee Kyoung-Ku;Han Sang-Bin
    • Journal of the Korean Society of Tobacco Science
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    • v.27 no.2
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    • pp.226-234
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    • 2005
  • The uncertainty of measurement in nitrate from burley leaf tobacco by continuous-flow analysis method was evaluated following internationally accepted guidelines. The sources of uncertainty associated with the analysis of nitrate were weight of standard and sample, purity of standard, dilution of standard solution, calibration curve, water content, etc. The calculation of uncertainty based on the GUM(Guide to the Expression of Uncertainty in Measurement) and EURACHEM/CITAC Guide. An expanded uncertainty was obtained by multiplying the combined standard uncertainty with a coverage factor (k) calculated from the effective degree of freedom. The concentration of nitrate from burley leaf tobacco was $2.09\%$ and the expanded uncertainty by multiplying by the coverage factor(k, 2.20) was $0.13\%\;at\;a\;95\%$ confidence level.

UNCERTAINTY AND SENSITIVITY STUDIES WITH THE PROBABILISTIC ACCIDENT CONSEQUENCE ASSESSMENT CODE OSCAAR

  • HOMMA TOSHIMITSU;TOMITA KENICHI;HATO SHINJI
    • Nuclear Engineering and Technology
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    • v.37 no.3
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    • pp.245-258
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    • 2005
  • This paper addresses two types of uncertainty: stochastic uncertainty and subjective uncertainty in probabilistic accident consequence assessments. The off-site consequence assessment code OSCAAR has been applied to uncertainty and sensitivity analyses on the individual risks of early fatality and latent cancer fatality in the population outside the plant boundary due to a severe accident. A new stratified meteorological sampling scheme was successfully implemented into the trajectory model for atmospheric dispersion and the statistical variability of the probability distributions of the consequence was examined. A total of 65 uncertain input parameters was considered and 128 runs of OSCAAR with 144 meteorological sequences were performed in the parameter uncertainty analysis. The study provided the range of uncertainty for the expected values of individual risks of early and latent cancer fatality close to the site. In the sensitivity analyses, the correlation/regression measures were useful for identifying those input parameters whose uncertainty makes an important contribution to the overall uncertainty for the consequence. This could provide valuable insights into areas for further research aiming at reducing the uncertainties.