• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.173-181
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• 2001

We calibrated a capacitance diaphragm gauge(CDG) of 1,333 Pa range by using ultrasonic interferometer manometer (UIM) that was a national low vacuum standards system. And its uncertainties were evaluated 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 uncertainties were $1.38 \times10^{-2}\; Pa\sim3.03 \times10^{-1} $Pa and the relative uncertainties(combined standard uncertainty/standard pressure) were $2.3 \times 10^{-4}\;Pa\sim7.9 X\times10^{-3} $Pa for this 1,333 Pa CDG.

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.212-213
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• 2009

• 한국가스학회:학술대회논문집
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• 2007.04a
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• pp.42-49
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• 2007

가스크로마토그래피 불꽃이온화검출기(FID)에서, 천연가스 표준물질만을 사용하여 분석할 때 발생할 수 있는 분석 불확도에 대하여 연구하였다. 일반적으로 $10^5$ 범위 농도까지 직선성이 확보된 것으로 알려진 FID 검출기에 대하여 실제 분석에서 동일한 직선성이 확보되는지를 확인하였다. 본 연구에서 7성분으로 조성된 천연가스용 표준가스를 샘프링 loop의 크기를 1.0mL, 0.50mL, 0.25mL로 변환시키면서 GC/FID를 사용하여 분석한 상대표준불확도 결과는 다음과 같다. 메탄은, 0.458 %, 에탄은 0.20247%, 프로판은 0.1497%, i-부탄은 0.1854 %, n-부탄은 0.2977%, i-펜탄은 0.263%, n-펜탄은 0.383%이었다. 각 경우에서 직선성 상대표준불확도값이 $0.15%{\sim}0.45 %$까지 이른다. 일반적으로 농도가 높은 메탄의 경우에 직선성 불확도값이 큰 값을 보여 주었고 농도범위가 1-5%인 $C2{\sim}C5$의 경우는 작은 직선성 표준불확도를 나타내었다.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.13-17
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• 2002

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.463-470
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• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• Analytical Science and Technology
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• v.19 no.6
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• pp.490-497
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• 2006

The sources of uncertainty in the analysis of liquified natural gas (LNG) process are evaluated. The uncertainty sources evaluated are the repeatability of measurement, non-linearity of GC, the uncertainty of standard gas used for calibration, difference of gas sampling and deviation after GC calibration and major revealed sources are the non-linearity of GC, the uncertainty of standard gas and the deviation after GC calibration. The determined values and uncertainties of methane and ethane as the major components are $90.0%mol/mol{\pm}1.9%$ (relative and 95% level of confidence) and $6.26%mol/mol{\pm}0.08$ (relative and 95% level of confidence), respectively. The contribution of uncertainty varies depending on the source of uncertainty and gas component. In the case of methane, non-linearity of GC, the uncertainty of standard gas and deviation after GC calibration contribute 0.28%, 0.25% and 0.24% of relative expanded uncertainty, respectively.

• Analytical Science and Technology
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• v.16 no.3
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• pp.185-190
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• 2003

We applied modified least square method (MLS) and ordinary least square method (OLS) to 1st order equation for the comparison of the uncertainties calculated by these methods. The uncertainty calculated by OLS covered statistically safe interval because it was over-estimated in many cases of measurement and concentration level. But, if the uncertainty of the concentration as a reference value was comparably large (about 5% of the relative standard deviation of random scattering from the regression line and about 7% of relative standard uncertainty of reference values), then uncertainty calculated by OLS was seriously under-estimated at high concentration level. It was revealed that the calculated uncertainty didn't cover statistically safe interval at the stated confidence level. It was found that the method, MLS, described in the previously article would be valid for this calculation of uncertainty.

• Progress in Superconductivity
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• v.14 no.1
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• pp.45-51
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• 2012

Microwave metrology for the thickness of metallic or superconductive films provides a new way to measure the film thickness in a non-invasive way by using microwave resonators, with the measurement accuracy affected by standard uncertainties in the resonator quality factor, temperature-dependent resonant frequency and the dimensions of the resonators. Here we study effects of the standard uncertainty in the thickness, $t_{cal}$, of a calibration $YBa_2Cu_3O_{7-{\delta}}$ (YBCO) film on the measured thicknesses, $t_{RF}$, by using a ~ 40 GHz microwave resonator. For the study, we used five YBCO films having the thicknesses of 70 - 360 nm, for which relative standard uncertainties in $t_{RF}$ due to that in $t_{cal}$ are obtained. The standard uncertainty in $t_{cal}$ was determined with the surface roughness of the film taken into account. It appeared that relative standard uncertainty in $t_{cal}$ significantly affects the $t_{RF}$ values, with the values of 1% (5%) in the former resulting in those of 1-2% (5-9%) for the latter at 10 K. Our results show that, for realizing relative standard uncertainties less than 5% in $t_{RF}$ for all the YBCO films, the surface roughness of the calibration films should be small enough to realize a relative standard uncertainty of less than 2.7% in $t_{cal}$.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.110-117
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• 2009

This work introduces the uncertainty evaluation formulation on color measurement of light sources and display devices, such as CIE 1931 (x, y) chromaticity, CIE 1960 (u, v) chromaticity, correlated color temperature, and distribution temperature. All the mentioned quantities are reduced from spectral data in the visible range, for which uncertainties are strongly correlated between different wavelengths. Using matrix algebra we have formulated the uncertainty propagation from the SI- traceable spectral irradiance standard to the individual color related measurement quantities taking the correlation between wavelengths into account. As a result, we have demonstrated uncertainty evaluation examples of 3 types of light sources: CIE illuminant A, LED white light, and LCD white light. This method can be applied to any other quantities based on spectral measurement such as solar irradiance, material color measurement, etc.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.160-161
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• 2010