• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2394-2398
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• 2013

Nicotine is the main component of environmental tobacco smoke, and its presence in indoor air is widely used as a secondhand-smoke indicator. Environmental tobacco smoke is a major source of indoor air pollution, but sufficient investigation of the uncertainty of its measurement, which mirrors the reliability of nicotine measurement, has not been performed. We calculated the uncertainty of measurement of indoor air nicotine concentration at low, medium, and high concentrations of 11.3798, 10.1977, $98.3768{\mu}g/m^3$, respectively, and we employed the Guide to the Expression of Uncertainty in Measurements (GUM), proposed by the International Organization for Standardization (ISO). The factors considered in determining the uncertainty were uncertainty of the calibration curve (calibration curve and repeated measurements), desorption efficiency, extraction volume, and sampling airflow (accuracy and acceptable limits of flowmeter). The measurement uncertainty was highest at low concentrations; the expanded measurement uncertainty is $0.9435{\mu}g/m^3$ and is represented as a relative uncertainty of 63.38%. At medium and high (concentrations, the relative uncertainty was 13.1% and 9.1%, respectively. The uncertainty of the calibration curve was largest for low indoor nicotine concentrations. To increase reliability of measurement in assessing the effect of secondhand smoke, measures such as increasing the sample injection rate ($1{\mu}L$ or more), increasing sampling volume to increase collected nicotine, and using gas chromatography-mass spectrometry (GC/MS) or GC/MS/MS, which has a lower quantitation threshold, rather than gas chromatography with nitrogen phosphorous detector, should be considered.

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.910-916
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• 1999

A current interest in chemistry concerns traceability of analytical measurements to the International System of Units (SI) and the proper estimation of their uncertainties in accordance with the internationally agreed guide provided by the International Organization for Standardization (ISO). Isotope dilution mass spectrometry (IDMS) is regarded as a primary method, which make the measurement results traceable to SI units without significant empirical correction factors. Our laboratory, as the national standards institute of Korea, participated in an intercomparison of environmental analysis, pp'-DDE in corn oil, which was organized by the CCQM under supervision of the CIPM to test feasibility of IDMS as a primary method for the trace analysis of organic compounds. In this report, we provide basic equations used for the calculation of the concentration of the analyte in a sample and a precise description of the processes for the evaluation of the uncertainties of the measurement results. Also, we report the experimental conditions adopted to improve the accuracy of the IDMS measurement. The principles contained in ？？Guide to the Expression of Uncertainty in Measurement'' provided by ISO are followed for the uncertainty evaluation.

• 한국소음진동공학회논문집
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• 제26권7호
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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.

• International Journal of Precision Engineering and Manufacturing
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• 제5권3호
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• pp.19-25
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• 2004

Pitch measurements of 150 nm one-dimensional grating standards were carried out using a contact mode atomic force microscopy with a high resolution three-axis laser interferometer. This measurement technique was named as the 'nano-metrological AFM'. In the nano-metrological AFM, three laser interferometers were aligned precisely to the end of an AFM tip. Laser sources of the three-axis laser interferometer in the nano-metrological AFM were calibrated with an I$_2$ stabilized He-Ne laser at a wavelength of 633 nm. Therefore, the Abbe error was minimized and the result of the pitch measurement using the nano-metrological AFM could be used to directly measure the length standard. The uncertainty in the pitch measurement was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM). The primary source of uncertainty in the pitch-measurements was derived from the repeatability of the pitch-measurements, and its value was about 0.186 nm. The average pitch value was 146.65 nm and the combined standard uncertainty was less than 0.262 nm. It is suggested that the metrological AFM is a useful tool for the nano-metrological standard calibration.

• 한국수자원학회논문집
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• 제50권8호
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• pp.521-535
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• 2017

음향 도플러 유속계(Acoustic Doppler Current Profiler, ADCPs)는 하천의 유량측정에 널리 사용되고 있으나, 유량 측정성과의 불확도를 평가하는 방법에 대하여 진행된 연구는 부족한 현실이며, 이는 실제 하천에서 유속 및 유량 등의 수리량을 조절하는 것이 현실적으로 불가능하여 ADCP의 불확도 요인별 실험 및 분석이 어렵기 때문이다. 유량 및 수리량의 측정 불확도를 평가하기 위하여 과학 및 공학 분야에서는 다양한 연구들이 진행되어 왔으며, 그 중 국제적으로 공인받고 있는 방법 중 하나가 GUM (Guide to the Expression of Uncertainty Measurement)이다. 본 연구에서는 GUM 표준안을 기반으로 ADCP의 유량 측정 불확도를 평가하기 위한 연구를 수행하였다. ADCP의 유량 측정 불확도 요인별 분석을 수행하기 위하여 유량 공급의 조절이 가능한 실 규모 수로를 보유하고 있는 하천실험센터에서 실험을 진행하였으며, ADCP의 측정 정확도에 영향을 미치는 수심, 측정 지점에서 하안까지의 거리, ADCP의 잠김 깊이, 유속 오차, 측정 시간, 반복 횟수, 하상 조건 등에 대한 측정 정확도 평가 실험을 수행하였다. ADCP로 유량을 측정하는 방법은 지점측정방식을 기반으로 유속-면적법을 통해 산정하는 방법과 일반적으로 사용되는 이동측정방식이 있으며, 본 연구에서는 ADCP의 지점측정방식을 통해 유량을 산정하는 Section-by-Section 방법으로 산정된 유량의 불확도를 평가하였다. 모든 측정 결과는 요인별 불확도 평가를 수행하기 위하여 유속은 ADV, 수심은 광파기로 측정된 결과와 비교하였다.

• Geomechanics and Engineering
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• 제12권6호
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• pp.871-882
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• 2017

Indirect measure of the tensile strength of laboratory samples is an important topic in rock engineering. One of the most important tests, the Brazilian strength test is performed to obtain the tensile strength of rock, concrete and other quasi brittle materials. Because the measurements are provided indirectly and the inspected rock materials may have heterogeneous properties, uncertainty quantification is required for a reliable test evaluation. In addition to the conventional measurement evaluation uncertainty methods recommended by the Guide to the Expression of Uncertainty in Measurement (GUM), such as Taylor's and Monte Carlo Methods, a fuzzy set-based approach is also proposed and resulting uncertainties are discussed. The results showed that when a tensile strength measurement is measured by a laboratory test, its uncertainty can also be expressed by one of the methods presented.

• 대한조선학회논문집
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• 제51권5호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.264-267
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• 2003

Pitch measurements of 150 nm pitch one-dimensional grating standards were carried out using an contact mode atomic force microscopy(C-AFM) with a high resolution three-axis laser interferometer. It was called as 'Nano-metrological AFM' In Nano-metrological AFM, Three laser interferometers were aligned well to the end of AFM tip. Laser sources of the three-axis laser interferometer in the nano-metrological AFM were calibrated with an I$_2$-stablilzed He-Ne laser at a wavelength of 633 nm. So, the Abbe error was minimized and the result of the pitch measurement using the nano-metrological AFM has a traceability to the length standard directly. The uncertainty in the pitch measurement was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement(GUM). The Primary source of uncertainty in the pitch-measurements was derived from repeatability of pitch-measurement, and its value was approx 0.186 nm. Expanded uncertainty(k=2) of less than 5.23 nm was obtained. It is suggested that the metrological AFM is a useful tool for the nano-metrological standard calibration.

• 한국정밀공학회지
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• 제21권11호
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• pp.75-82
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• 2004

A metrological atomic force microscope (M-AFM) was developed fur the length measurements of nanometer range, through the modification of a commercial AFM. To eliminate nonlinearity and crosstalk of the PZT tube scanner of the commercial AFM, a two-axis flexure hinge scanner employing built-in capacitive sensors is used for X-Y motion instead of PZT tube scanner. Then two-dimensional displacement of the scanner is measured using two-axis heterodyne laser interferometer to ensure the meter-traceability. Through the measurements of several specimens, we could verify the elimination of nonlinearity and crosstalk. The uncertainty of length measurements was estimated according to the Guide to the Expression of Uncertainty in Measurement. Among several sources of uncertainty, the primary one is the drift of laser interferometer output, which occurs mainly from the variation of refractive index of air and the thermal stability. The Abbe error, which is proportional to the measured length, is another primary uncertainty source coming from the parasitic motion of the scanner. The expanded uncertainty (k =2) of length measurements using the M-AFM is √(4.26)$^2$+(2.84${\times}$10$^{-4}$ ${\times}$L)$^2$(nm), where f is the measured length in nm. We also measured the pitch of one-dimensional grating and compared the results with those obtained by optical diffractometry. The relative difference between these results is less than 0.01 %.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1219-1230
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• 2004

Comparing to the gravimetric and volumetric method, the flowmeter calibration based on the master meter method is relatively economical and convenient, especially for high flowrate. The uncertainty of flow quantity and flowrate using the master meter method was evaluated according to the GUM (Guide to the Expression of Uncertainty in Measurement). In order to apply for the wider flow range, two master meters (electromagnetic flow meter) were employed as reference flowmeters. The uncertainty of the master meter was obtained by combining the statistical variation of the repeated measurements and the variation of fluid density and pipe material due to temperature and pressure changes were scrutinized. for a practical application, the uncertainty of calibrator, whose measuring capacity of 1000 ㎥/h obtained by employing two 500 ㎥/h electromagnetic How meters, was evaluated. The uncertainty budget shows the quantitative contribution of each uncertainty component to the overall uncertainty of the calibrator. As a result, it was found that the dominant uncertainties were from the master meter, which was evaluated statistically, and from the process of least squares fitting. On the contrary, the uncertainties arising from the variation of the fluid density and the pipe volume due to the temperature and pressure were negligible.