• Title, Summary, Keyword: Uncertainty

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Model Classification and Evaluation of Measurement Uncertainty (측정 불확도 모형 분류 및 평가)

  • Choi, Sung-Woon
    • Journal of the Korea Safety Management & Science
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    • v.9 no.1
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    • pp.145-156
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    • 2007
  • This paper is to propose model classification and evaluation of measurement uncertainty. In order to obtain type A and B uncertainty, variety of measurement mathematical models are illustrated by example. The four steps to evaluate expanded uncertainty are indicated as following; First, to get type A standard uncertainty, measurement mathematical models of single, double, multiple, design of experiment and serial autocorrelation are shown. Second, to solve type B standard uncertainty measurement mathematical models of empirical probability distributions and multivariate are presented. Third, type A and B combined uncertainty, considering sensitivity coefficient, linearity and correlation are discussed. Lastly, expanded uncertainty, considering degree of freedom for type A, B uncertainty and coverage factor are presented with uncertainty budget. SPC control chart to control expanded uncertainty is shown.

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.

Measurement Uncertainty of Vibration Testing Result with Including Uncertainty of Testing Facilities (시험장비의 특성을 고려한 진동시험결과에 대한 측정불확도 추정)

  • Moon, Seok-Jun;Chung, Jung-Hoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.7
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    • pp.781-786
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    • 2016
  • All measurements are subject to uncertainty and a measurement result is complete only when it is accompanied by a statement of the associated uncertainty. By international agreement, this uncertainty has a probabilistic basis and reflects incomplete knowledge of the quantity value. The "Guide to the Expression of Uncertainty in Measurement", commonly known as the GUM, is the definitive document on this subject. The requirements for estimation of measurement uncertainty apply to all results provided by calibration laboratories and results produced by testing laboratories under the optional circumstances. In this paper, a procedure for estimation of measurement uncertainty from vibration testing is proposed on KS F 2868:2003 as an example. Both Type A and Type B evaluation of uncertainty are considered to calculate the combined standard uncertainty and expanded uncertainty.

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.

Influence of Uncertainty and Uncertainty Appraisal on Self-management in Hemodialysis Patients (혈액투석 환자의 불확실성과 불확실성 평가가 자기관리에 미치는 영향)

  • Jang, Hyung Suk;Lee, Chang Suk;Yang, Young Hee
    • Journal of Korean Academy of Nursing
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    • v.45 no.2
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    • pp.271-279
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    • 2015
  • Purpose: This study was done to examine the relation of uncertainty, uncertainty appraisal, and self-management in patients undergoing hemodialysis, and to identify factors influencing self-management. Methods: A convenience sample of 92 patients receiving hemodialysis was selected. Data were collected using a structured questionnaire and medical records. The collected data were analyzed using descriptive statistics, t-test, ANOVA, Pearson correlations and multiple regression analysis with the SPSS/WIN 20.0 program. Results: The participants showed a moderate level of uncertainty with the highest score being for ambiguity among the four uncertainty subdomains. Scores for uncertainty danger or opportunity appraisals were under the mid points. The participants were found to perform a high level of self-management such as diet control, management of arteriovenous fistula, exercise, medication, physical management, measurements of body weight and blood pressure, and social activity. The self-management of participants undergoing hemodialysis showed a significant relationship with uncertainty and uncertainty appraisal. The significant factors influencing self-management were uncertainty, uncertainty opportunity appraisal, hemodialysis duration, and having a spouse. These variables explained 32.8% of the variance in self-management. Conclusion: The results suggest that intervention programs to reduce the level of uncertainty and to increase the level of uncertainty opportunity appraisal among patients would improve the self-management of hemodialysis patients.

Quantitative uncertainty analysis for the climate change impact assessment using the uncertainty delta method (기후변화 영향평가에서의 Uncertainty Delta Method를 활용한 정량적 불확실성 분석)

  • Lee, Jae-Kyoung
    • Journal of Korea Water Resources Association
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    • v.51 no.spc
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    • pp.1079-1089
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    • 2018
  • The majority of existing studies for quantifying uncertainties in climate change impact assessments suggest only the uncertainties of each stage, and not the total uncertainty and its propagation in the whole procedure. Therefore, this study has proposed a new method, the Uncertainty Delta Method (UDM), which can quantify uncertainties using the variances of projections (as the UDM is derived from the first-order Taylor series expansion), to allow for a comprehensive quantification of uncertainty at each stage and also to provide the levels of uncertainty propagation, as follows: total uncertainty, the level of uncertainty increase at each stage, and the percentage of uncertainty at each stage. For quantifying uncertainties at each stage as well as the total uncertainty, all the stages - two emission scenarios (ES), three Global Climate Models (GCMs), two downscaling techniques, and two hydrological models - of the climate change assessment for water resources are conducted. The total uncertainty took 5.45, and the ESs had the largest uncertainty (4.45). Additionally, uncertainties are propagated stage by stage because of their gradual increase: 5.45 in total uncertainty consisted of 4.45 in emission scenarios, 0.45 in climate models, 0.27 in downscaling techniques, and 0.28 in hydrological models. These results indicate the projection of future water resources can be very different depending on which emission scenarios are selected. Moreover, using Fractional Uncertainty Method (FUM) by Hawkins and Sutton (2009), the major uncertainty contributor (emission scenario: FUM uncertainty 0.52) matched with the results of UDM. Therefore, the UDM proposed by this study can support comprehension and appropriate analysis of the uncertainty surrounding the climate change impact assessment, and make possible a better understanding of the water resources projection for future climate change.

A Study on Estimation uncertainty of measurement in mechanical characteristic exam for Plastic materials (플라스틱재료의 기계적 특성시험 불확도추정에 대한 고찰)

  • Kim Won-kyung;Kwon Sung-Tae;Kim Jung-Nam
    • Proceedings of the KSR Conference
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    • pp.301-306
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    • 2003
  • Recently, uncertainty of measurement became a major concern for the people working on the laboratory evaluation and accreditation. 'uncertainty of measurement is a parameter associated with the result of a measurement that characteristics the dispersion of the value that could reasonably be attributed to the measured.' This study analysed how to estimate uncertainty of measurement in mechanical characteristic exam for Plastic material. its uncertainty was estimated according to International Organization for Standardization(ISO), they were named to A type uncertainty, B type uncertainty, combined standard uncertainty, and expanded uncertainty. We obtained that the combined standard uncertainty was 0.96697 MPa and the expanded uncertainty was 2.291MPa.

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Impact of Uncertainty on the Anxiety of Hospitalized Pregnant Women Diagnosed with Preterm Labor: Focusing on Mediating Effect of Uncertainty Appraisal and Coping Style (입원한 조기진통 임부의 불확실성이 불안에 미치는 영향: 불확실성 평가와 대처양상의 매개효과를 중심으로)

  • Kim, Eun Mi;Hong, Sehoon
    • Journal of Korean Academy of Nursing
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    • v.48 no.4
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    • pp.485-496
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    • 2018
  • Purpose: This study aimed to test the mediating effect of uncertainty appraisal and coping style in the relation between uncertainty and anxiety in hospitalized pregnant women diagnosed with preterm labor. Methods: The participants were 105 pregnant women diagnosed with preterm labor in hospitals in Korea. Data were collected from July to October 2017. The measurements included the Uncertainty in Illness Scale, Uncertainty Appraisal Scale, Coping Style Scale, and State Anxiety Inventory. Data were analyzed using descriptive statistics, an independent t-test, correlation, and multiple regression following the Baron and Kenny method and Sobel test for mediation. Results: The mean score for anxiety was 2.29 out of 4.00 points and for uncertainty it was 2.46 out of 5.00 points. There were significant correlations among uncertainty, uncertainty danger appraisal, uncertainty opportunity appraisal, problem-focused coping, emotion-focused coping, and anxiety. Uncertainty danger appraisal (${\beta}=.64$, p<.001) had a complete mediating effect in the relation between uncertainty and anxiety (Z=4.54, p<.001). Uncertainty opportunity appraisal (${\beta}=-.45$, p<.001) had a complete mediating effect in the relation between uncertainty and anxiety (Z=3.28, p<.001). Emotion-focused coping (${\beta}=-.23$, p=.021) had a partial mediating effect in the relation between uncertainty and anxiety (Z=2.02, p=.044). Conclusion: Nursing intervention programs focusing on managing uncertainty appraisal and improving emotion-focused coping are highly recommended to decrease anxiety in hospitalized pregnant women diagnosed with preterm labor.

Foreign Exchange Rate Uncertainty in Korea

  • Lee, Seojin
    • East Asian Economic Review
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    • v.24 no.2
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    • pp.165-184
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    • 2020
  • Applying Ismailov and Rossi (2018), I newly construct the Korea FX uncertainty based on the density distribution of historical forecast errors. This uncertainty index properly captures the rare but significant events in the Korean currency market and provides information distinct from other uncertainty measures in recent studies. I show that 1) FX uncertainty arising from unexpected depreciation has a stronger impact on Korea-U.S. exchange rates and that 2) macro variables, such as capital flows or interest rate differentials, have predictive ability regarding Korea FX uncertainty for short horizons. These findings enable us to predict the events of sudden currency crashes and understand the Korea-U.S. exchange rate dynamics.

Assessing the Effects of Supply Uncertainty on Inventory-Related Costs (공급업자의 공급불확실성이 재고관리 비용에 미치는 효과에 관한 연구)

  • 박상욱
    • Journal of the Korean Operations Research and Management Science Society
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    • v.26 no.3
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    • pp.105-117
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    • 2001
  • This paper models supply uncertainty in the dynamic Newsboy problem context. The system consists of one supplier and one retailer who places an order to the supplier every period to meet stochastic demand. Supply uncertainty is modeled as the uncertainty in quantities delivered by the supplier. That is, the supplier delivers exactly the amount ordered by the retailer with probability of $\beta$ and the amount minus K with probability of (1-$\beta$). We formulate the problem as a dynamic programming problem and prove that retailer’s optimal replenishment policy is a stationary base-stock policy. Through a numerical study, we found that the cost increase due to supply uncertainty is significant and that the costs increase more rapidly as supply uncertainty increases. We also identified the effects of various system parameters. One of the interesting results is that as retailer’s demand uncertainty, the other uncertainty in our model, increases, the cost increase due to supply uncertainty becomes less significant.

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