• Title, Summary, Keyword: Measurement 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 and 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.

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.

Measurement Uncertainty for Analytical Method of Hyaluronic Acid Used as a Dietary Supplement (식이보충제로 사용되는 히알루론산의 분석법에 대한 불확도 산정)

  • Park, Sang-Wook;Kim, Hyung Bum;Kim, Kwang Joon;Lee, Wonjae
    • KSBB Journal
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    • v.32 no.1
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    • pp.54-62
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    • 2017
  • This study aimed to estimate the measurement uncertainty related to determination of hyaluronic acid used as a dietary supplement by high-performance liquid chromatography. According to the guidelines of the Association of Official Analytical Chemists, the analytical processes for determination of hyaluronic acid were performed. And the measurement uncertainty obtained during the analytical processes were expressed in accordance with mathematical/ statistical guidances of GUM (Guide to the Expression of Uncertainty in Measurement) & EURACHEM (Focus for Analytical Chemistry in Europe) for the analytical operations. For the uncertainty in measurement produced based on this analytical method, the expanded uncertainty was calculated by using the relative standard uncertainty between analytical results and sources of uncertainty in measurement (sample weight, final volume, extraction volume, standard solution, matrix and instrument etc). In the results of 95% confidence interval, it was calculated that the uncertainty in measurement was $57.75{\pm}8.76{\mu}g/kg$ (k=2.0). Therefore, it showed that the measurement uncertainty obtained by this analytical method influences on 15.2% of the contents of hyaluronic acid as the analytical results.

A Study on Estimation of Uncertainty in Measurement of Light Impact Sound Insulation of Floors (공동주택 경량바닥충격음 측정불확도 추정에 관한 연구)

  • Go, Jong-Chul;Lee, Jong-In;Kim, Hyun-Bae;Lee, Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1409-1416
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    • 2006
  • In measuring, uncertainty in measurement is essential to improve measuring reliability. Currently, however, in measuring impact sound insulation of floors, there are no guidelines to estimate uncertainty in measurement. In addition, the concept of uncertainty in rating is required to recognize the relation between measuring and rating. Therefore, through this paper, the efforts have been made to establish uncertainty in measurement and rating of light impact insulation of floors. The result of estimating of uncertainty in measurement and rating in our laboratory is considered reliable, considering ${\pm}0.46{\sim}1.44dB$ of uncertainty in measurement and 1 dB of uncertainty in rating.

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A Study on the Measurement Uncertainty of Flowmeter Calibrator (유량계 교정장치의 측정불확도에 관한 연구)

  • Im, Gi-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.4
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    • pp.561-571
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    • 2001
  • The standard uncertainty of flowrate measurement is obtained by combining that of independent variables. Gravimetric and volumetric method were applied to determine the flowrate and the standard uncertainties of flowrate measurement by both methods were evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainties of determining the flowrate were estimated from the sensitivity coefficient and the standard uncertainty of independent variables. For practical application, the methods for evaluating and expressing uncertainty in flow measurement were discussed. It was found that the uncertainties of the weighing and time measurement in gravimetric method, the volume and time measurement in volumetric method have dominant influence on that of flowrate measurement. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of flowrate measurement is shown clearly.

Measurement Uncertainty Analysis of a Turbine Flowmeter for Fuel Flow Measurement in Altitude Engine Test (엔진 고공 시험에서 연료 유량 측정용 터빈 유량계의 측정 불확도 분석)

  • Yang, In-Young
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.1
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    • pp.42-47
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    • 2011
  • Measurement uncertainty analysis of fuel flow using turbine flowmeter was performed for the case of altitude engine test. SAE ARP4990 was used as the fuel flow calculation procedure, as well as the mathematical model for the measurement uncertainty assessment. The assessment was performed using Sensitivity Coefficient Method. 11 parameters involved in the calculation of the flow rate were considered. For the given equipment setup, the measurement uncertainty of fuel flow was assessed in the range of 1.19~1.86 % for high flow rate case, and 1.47~3.31 % for low flow rate case. Fluctuation in frequency signal from the flowmeter had the largest influence on the fuel flow measurement uncertainty for most cases. Fuel temperature measurement had the largest for the case of low temperature and low flow rate. Calibration of K-factor and the interpolation of the calibration data also had large influence, especially for the case of very low temperature. Reference temperature, at which the reference viscosity of the sample fuel was measured, had relatively small contribution, but it became larger when the operating fuel temperature was far from reference temperature. Measurement of reference density had small contribution on the flow rate uncertainty. Fuel pressure and atmospheric pressure measurement had virtually no contribution on the flow rate uncertainty.

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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Uncertainty assessment for a towed underwater stereo PIV system by uniform flow measurement

  • Han, Bum Woo;Seo, Jeonghwa;Lee, Seung Jae;Seol, Dong Myung;Rhee, Shin Hyung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.5
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    • pp.596-608
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    • 2018
  • The present study aims to assess test uncertainty assessment method of nominal wake field measurement by a Stereoscopic Particle Image Velocimetry (SPIV) system in a towing tank. The systematic uncertainty of the SPIV system was estimated from repeated uniform flow measurements. In the uniform flow measurement case, time interval between image frames and uniform flow speed were varied to examine the effects of particle displacement and flow around the SPIV system on the systematic standard uncertainty. The random standard uncertainty was assessed by repeating nominal wake field measurements and the estimated random standard uncertainty was compared with that of laser Doppler velocimetry. The test uncertainty assessment method was applied to nominal wake measurement tests of a very large crude oil carrier model ship. The nominal wake measurement results were compared with existing experimental database by other measurement methods, with its assessed uncertainty.

Development of a Model System of Uncertainty Evaluations for Multiple Measurements by Isotope Dilution Mass Spectrometry: Determination of Folic Acid in Infant Formula

  • Kim, Byung-Joo;Hwang, Eui-Jin;So, Hun-Young;Son, Eun-Kyung;Kim, Yong-Seong
    • Bulletin of the Korean Chemical Society
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    • v.31 no.11
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    • pp.3139-3144
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    • 2010
  • A model system has been established for the evaluation of the uncertainty of the value from measurements of multiple subsamples by isotope dilution mass spectrometry (IDMS). In this report, we apply this model system for the evaluation of measurement uncertainty in determination of folic acid in infant formula. Five subsamples were analyzed by IDMS. The mean of the measurement results of the five subsamples was assigned as the final measurement value. The standard deviation (s) of the results from five subsamples was attributable to repeatability of the measurement. The uncertainty components in the IDMS measurement methods were categorized into two groups. Group I includes uncertainty components which give common systematic effects to all subsamples and do not contribute to the variation among multiple measurements (repeatability). Group II includes uncertainty components that give random effects on the measurement results, and are related with the measurement repeatability. These random effects are attributed to s. Therefore, the uncertainty of the final value was calculated by combining the standard deviation of the mean of multiple measurements, $s/{\surd}n$ (where n = 5), and the measurement uncertainty associated with the uncertainty components that give systematic effects.