• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.29-38
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• 2018

Background: Radon contributing about 42% of annual average dose, mainly comes from soil. In this paper, standard measurement procedures for soil radon exhalation rate are suggested and their measurement uncertainties are analyzed. Materials and Methods: We used accumulation method for estimating surface exhalation rate. The closed-loop measurement system was made up with a RAD7 detector and a surface chamber. Radon activity concentrations in the system were observed as a function of time, with data collection of 5 and 15-minute and the measurement time of 4 hours. Linear and exponential fittings were used to obtain radon exhalation rates from observed data. Standard deviations of measurement uncertainties for two approaches were estimated using usual propagation rules. Results and Discussion: The exhalation rates (E) from linear approach, with 30 minutes measurement time were $44.8-48.6mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.14-2.32atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with relative measurement uncertainty of about 10%. The contributions of fitting parameter A, volume (V) and surface (S) to the estimated measurement uncertainty of E were 59.8%, 30.1% and 10.1%, in average respectively. In exponential fitting, at 3-hour measurement we had E ranged of $51.6-69.2mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.46-3.30atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with about 15% relative uncertainty. Fitting with 4-hour measurement resulted E about $51.3-68.2mBq{\cdot}m^{-2} {\cdot}s^{-1}$ or $2.45-3.25atom{\cdot}cm^{-2}{\cdot}s^{-1}$ with 10% relative uncertainty. The uncertainty contributions in exponential approach were 75.1%, 13.4%, 8.7%, and 2.9% for total decay constant k, fitting parameter B, V, and S, respectively. Conclusion: In obtaining exhalation rates, the linear approach is easy to apply, but by saturation feature of radon concentrations, the slope tends to decrease away from the expected slope for extended measurement time. For linear approach, measurement time of 1-hour or less was suggested. For exponential approach, the obtained exhalation rates showed similar values for any measurement time, but measurement time of 3-hour or more was suggested for about 10% relative uncertainty.

• 분석과학
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• 제19권6호
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• pp.490-497
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• 2006

액화 천연가스(LNG) 공정 분석 결과의 불확도 요인을 평가하였다. 평가된 불확도 요인은 측정 반복성, 사용된 GC의 비 직선성, 사용된 표준가스의 불확도, 시료 채취 방법에 따른 농도 변화 그리고 교정 후의 기기 변동이었으며, 이 중에서 중요한 불확도 요인은 사용된 GC의 비 직선성, 사용된 표준가스의 불확도 그리고 교정 후의 기기 변동이었다. 주요 성분인 메탄 및 에탄의 경우, 각각 $90.0{\pm}0.9%mol/mol$(확장불확도, 95% 신뢰 수준) 및 $6.26{\pm}0.08%mol/mol$(확장불확도, 95% 신뢰 수준)이었다. 가스 성분원소별로 각 불확도 요소의 기여 정도는 차이가 있었고, 메탄 분석의 경우 사용된 GC의 비 직선성의 상대 표준불확도가 0.28%, 사용된 표준가스의 상대 표준불확도가 0.25%, 그리고 교정 후의 기기 변동에 의한 상대 표준불확도가 0.24%이었다.

• 분석과학
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• 제16권3호
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• pp.185-190
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• 2003

회귀식 사용에 따른 불확도 계산의 정확성을 조사하기 위하여, 수정된 방법의 최소제곱법(Modified Least Square Method, MLS)과 회귀식에서 일반적으로 적용되는 불확도 처리 과정을 각각 1차 식에 적용하고 비교하였다. 회귀식에서 일반적으로 적용되는 불확도 처리 과정에서, 대부분의 경우 불확도 값이 크게 계산되고 있어 확률적으로 안전한 범위를 표기할 수 있는 것으로 평가되었다. 그러나, 표준시료 농도의 상대 표준불확도가 클 때 (교정점이 우발적으로 흩어지는 정도의 표준 편차가 5% 수준, 표준시료 농도의 상대 표준불확도가 7% 수준) 회귀식에서 일반적으로 적용되는 불확도 계산 방법으로 얻은 값이 고 농도 측정에서 매우 작게 평가되고 있어 확률적으로 매우 위험한 것으로 평가되었다. 이 경우, 통계학적으로 불확도를 정확히 계산하기 위하여, 수정된 방법의 최소제곱법이 유리하다고 판단하였다.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1130-1138
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• 2005

A national standard system for the petroleum field has been developed to calibrate and test the oil flow meters in Korea. The operating system and the uncertainty of the system were evaluated by the peer reviewers of foreign national metrology institutes in 2002. Since the characteristics of the system might be changed by time, the uncertainty of the system is reevaluated with the consideration of the long term stability of the system. It is found that the system has a relative expanded uncertainty of 0.048 $\%$ in the range of $15\~120\;m^3/h$. According to the uncertainty budget, the uncertainties of the fluid density and the final mass measurement, which are temperature dependent, contribute about $94\%$ of the total uncertainty in the oil flow standard system

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.656-659
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• 2004

As the demand for traceable calibrations of torque measuring devices has considerably increased both in the production sector and in research institutes, suitable standard machines had to be developed at the Korea Research Institute of Standards and Science. Owing to its special design, the small uncertainty of measurement required for the realization of the static torque can be reached (relative uncertainty of measurement ＆lt; 5$\times$10$^{-5}$ in the measurement range between 500 and 2000 Nm, and ＆lt; 1$\times$10$^{-4}$ in the measurement range from 10 to 500 Nm). The relative discrepancy between our torque calibration results of 2 kNm and PTB s (Physikalisch Technische Bundesanstalt, Germany) results was less than 2$\times$10$^{-5}$ , which confirming our uncertainty estimation.

• Asia Marketing Journal
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• 제19권3호
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• pp.45-74
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• 2017

The current research proposes to fill a research gap by testing how reward uncertainty, different types of motivation, as well as individual risk-taking attitude affect consumers' promotion participation. Being offered with an uncertain reward, relative to individuals with extrinsic motivation, individuals with intrinsic motivation will have greater intention to participate in marketing promotion. In contrast, being offered with a certain reward, relative to individuals with intrinsic motivation, individuals with extrinsic motivation will have greater intention to participate in marketing promotion. This effect arises only among consumers having a low level of risk-taking attitude. For consumers having a high level of risk-taking attitude, their participation intention shows no significant difference between the two motivation type groups, under both certain and uncertain reward conditions. With an understanding of how consumer's response heterogeneously to promotions involving rewards, marketers can better understand not only how to use this promotional tactic more effectively, but also how to better allocate their budget for promotions.

• 한국수자원학회논문집
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• 제56권8호
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• pp.509-520
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• 2023

가뭄은 강수량, 토양수분 그리고 유출량 등 여러 가지 요인으로부터 영향을 받으며, 가뭄의 상황 판단을 위하여 다양한 가뭄지수가 널리 활용되고 있다. 가뭄지수의 산정에 활용되는 수문기상학적 자료와 가뭄지수 산정공식에 따라서 지수값은 달라지며, 가뭄 상황에 대한 판단에도 차이가 발생 할 수 있다. 본 연구에서는 국내외에서 널리 활용되는 표준강수지수(SPI)의 산정과정에서 결정해야 하는 강수량의 자료길이, 누적기간, 확률분포 모형, 매개변수 추정기법 등을 불확실성 영향 요인으로 가정하고, 각각의 조합에 대한 불확실성을 평균제곱근오차와 선형혼합모형(LMM)을 활용하여 평가하였다. 평균제곱오차는 SPI 산정과정에 발생되는 전반적인 오차를 추정하며, LMM은 영향 요인들의 상대적인 불확설성을 평가하는데 활용되었다. 그 결과, SPI 산정에 활용된 자료의 기간과 누적기간이 길어질수록 평균제곱오차가 감소하였다. LMM을 통하여 불확실성 영향요인들의 기여도를 비교한 결과, SPI의 불확실성에는 자료기간의 영향이 가장 크게 나타났다. 또한, 자료기간이 증가하면, 자료기간에 의한 불확실성은 감소하고 누적기간과 매개변수 추정기법에 의한 불확실성이 상대적으로 증가하였다. 본 연구 결과, SPI 산정과정에서 발생되는 불확실성을 줄이기 위해서는 장기간의 자료 확보가 우선이며, 자료의 특성을 적절히 반영하는 확률분포모형과 매개변수 추정기법이 적용되어야 한다.

• KSBB Journal
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• 제32권1호
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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.

• 아태비즈니스연구
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• 제14권4호
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• pp.319-330
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• 2023

Purpose - The purpose of this paper is to examine the connectedness between categorical economic policy uncertainty (monetary, fiscal, trade and foreign exchange policy uncertainty) indexes and option-implied volatility index in Korea, Japan and the US. Design/methodology/approach - This paper employs the Diebold-Ylmaz (2012) model based on a VAR and generalized forecast error variance decomposition. This paper also conducts regression analyses to investigate whether the volatility indexes are explained by categorical policy uncertainty indexes. Findings - First, we find the total connectedness is stronger in Korea and Japan relative to the US. Second, monetary, fiscal, and foreign exchange policy uncertainty indexes are connected to each other but trade policy uncertainty index is not. Third, the volatility index in Japan and the US is mainly associated with monetary policy uncertainty while the volatility index in Korea is explained by fiscal policy uncertainty index. Research implications or Originality - To our knowledge, this is the first study to investigate the connectedness among categorical policy uncertainty indexes and the volatility index in Korea, Japan, and the US. The empirical results on the connectedness suggest that transparent policy and communication with the market in one type of policy would reduce the uncertainty in other policies.

• 한국정밀공학회지
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• 제24권10호
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• pp.91-98
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• 2007

This paper describes the development of the calibration system for a multi-axis force/moment sensor and its uncertainty evaluation. This calibration system can generate the continuous forces (${\pm}Fx,\;{\pm}Fy$ and ${\pm}Fz$) and moments (${\pm}Mx,\;{\pm}My$ and ${\pm}Mz$). Many kinds of multi-axis force/moment sensors in industries should be carried out the characteristic test or the calibration with the calibration system that can generate the forces and the moments. The calibration systems have been already developed are the disadvantages of the low capacity, the generation of step forces(10N, 20N ...) and step moments(1Nm, 2Nm ...) with weights, the high coasts in manufacture and so on. In this paper, the calibration system for a multi-axis force/moment sensor that can generate the continuous three forces and three moments was developed. Their ranges are $0{\sim}2000N$ in all force-directions and $0{\sim}400Nm$ in all moment-directions. And the system was evaluated in the expanded relative uncertainty. They were ${\pm}0.0004$ in all forces ${\pm}Fx,\;{\pm}Fy$ and ${\pm}Fz$, and ${\pm}0.0004$ in all moments ${\pm}Mx,\;{\pm}My$ and ${\pm}Mz$.