• Korean Journal of Optics and Photonics
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• v.21 no.2
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• pp.46-52
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• 2010

A theory of bidirectional reflectance-distribution function (BRDF), a newly developed BRDF measurement system, and a method for evaluating the uncertainty of BRDF measurements are presented. The BRDF measurement system which measures BRDF in a wavelength range of (380~1500) nm with an angle range of $(-75{\sim}75)^{\circ}$ was installed. The measurement uncertainties, consisting of correlated terms and uncorrelated terms, were evaluated for the BRDF measurement system, resulting in the relative expanded uncertainty less than 3% (k=2).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1265-1267
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• 2006

현재 ISO 에서는 공구제조업체에서 해당 공구의 수전달 진동을 측정하여 제시하도록 하는 규격을 제정 중에 있으며, 이를 위해서는 공구에서 발생하는 진동과 영향을 평가하는 기술이 확보되어야 하며, 이 과정에서 측정 불확도 수준을 결정하는 것이 매우 중요하다고 하겠다. 본 연구에서는 동력 공구 작업시 작업자의 손으로 전달되는 진동을 측정하고 그 영향을 평가함에 있어서 발생할 수 있는 불확도를 분석하였다. 먼저, ISO 5349 규격을 적용함에 있어서 존재하는 불확도 인자들을 분류하고, 각 인자들이 어느 정도 수준의 불확도를 발생시키는지 시험을 통해서 확인하고 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.7
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• pp.647-656
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• 2014

To supplement the ISO-GUM method for the evaluation of measurement uncertainty, a simulation program using the Monte Carlo method (MCM) was developed, and the MCM and GUM methods were compared. The results are as follows: (1) Even under a non-normal probability distribution of the measurand, MCM provides an accurate coverage interval; (2) Even if a probability distribution that emerged from combining a few non-normal distributions looks as normal, there are cases in which the actual distribution is not normal and the non-normality can be determined by the probability distribution of the combined variance; and (3) If type-A standard uncertainties are involved in the evaluation of measurement uncertainty, GUM generally offers an under-valued coverage interval. However, this problem can be solved by the Bayesian evaluation of type-A standard uncertainty. In this case, the effective degree of freedom for the combined variance is not required in the evaluation of expanded uncertainty, and the appropriate coverage factor for 95% level of confidence was determined to be 1.96.

• 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.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.562-571
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• 2003

A series of factors such as sampling, pretreatment measurement, volume estimation which induces uncertainty of the calculated radioactivity in liquid effluent released from a nuclear power plant were analyzed. It is innately impossible to estimate exact error of the calculated radioactivity, since most of the input parameters are determined by a single measurement and true value of the released radioactivity cannot be known. In this paper, a systematic model to calculate uncertainty of the released liquid radioactivity was developed based upon the guidance report published by the ISO in 1993, and the model was applied to a set of hypothetical batch release conditions. As a result, the Priority of each input parameter was turned out to be (1) wastewater volume, (2) sample volume, and (3) measured radioactivity of the sample. In addition, probability distribution of the released radioactivity was simulated by Monte Carlo method combining the probability distribution of each input parameter It was shown that the radioactivity released to the environment, which has been reported as a single value, has a certain form of probability distribution.

• Journal of the Korean Chemical Society
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• v.67 no.5
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• pp.319-332
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• 2023

Ever since the development of the Guide to the Expression of Uncertainty in Measurement (GUM) in 1993, the concept of measurement uncertainty has been considered a core concept in metrology and the importance of proper uncertainty evaluation has continuously been increasing. Unfortunately, few papers in Korean are available that introduce the concept of measurement uncertainty and the GUM correctly and in sufficient detail. This review describes in detail the mathematical, historical, and philosophical background behind the concept of measurement uncertainty and the GUM, and also discusses some special aspects of uncertainty evaluation in chemical analysis.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.165-175
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• 2003

The concept of measurement uncertainty has been recognised for many years since "Guide to the Expression of Uncertainty in Measurement" was published 1993 by ISO. This study firstly propose the mathematical model to evaluate uncertainty considering the dispersion of samples because the mathematical model of a measurement is an important to evaluate uncertainty, and it must contains every quantify which contribute significantly to uncertainty in the measurement result. Secondly the standard uncertainty of the result of a measurement, namely combined standard uncertainty is evaluated using the law of propagation of uncertainty, what is termed in GUM method. In GUM method, a measurand is usually approximated by a linear function of its variables by the transforming its input quantities. Furthermore central limit theorem is applied to the input quantity. However the mathematical model of a measurement is generally not always a linearity function, and a distribution function of input or output quantity is not necessarily normal distribution. Then, in some cases GUM method is not favorable to evaluate a measurement uncertainty. Therefore this study propose a new method and its algorithm which use the Monte-carlo simulation to evaluate a measurement uncertainty in both case of linearity or non-linearity function. function.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.104-104
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• 2016

소규모 하천에서의 평수기 유량 측정은 일반적으로 지점식 초음파 유속계, 프로펠러 유속계 등을 활용해 도섭법으로 측정된 유속 측정성과를 기반하여 유속-면적법으로 산정된다. 유속-면적법으로 측정된 유량 측정 성과는 횡방향 측선의 수, 수심방향 측점의 수, 측정 시간, 수심 등 제반 측정 인자에 의해 영향을 받고 유량 불확도는 각 인자 별 오차에 영향을 받는다. ISO 748 (2007)과 ISO 1088 (2007)은 유속-면적법 적용방법, 현장 측정 가이드라인, 불확도 인자 별 적용 요건에 따른 오차, 최종 유량 불확도 산정 기법을 제시하였다. 따라서, 국내외 유량조사 기관에서는 유속면적법을 적용할 경우, ISO에서 제시된 인자 별 오차 및 유량 불확도 산정 기법을 기반으로 유량 불확도를 산정해왔다. ISO 748과 1088은 다양한 규모의 실제 하천에서 관측된 자료를 기반으로 횡방향 측선 수, 수심방향 측점 수 (2점법, 3점법 등), 측정 시간 등과 관련된 인자 별 오차를 표로 상세하게 제시하였고 실무에서는 별도 추가 검증없이 사용해 왔다. 그러나, ISO에서 유속-면적법 유량 측정 불확도를 평가하기 위해 사용된 측정자료는 유량을 제어하기 힘들고 유속 측정 상황이 유출 조건 별로 상이한 현장 자료를 기반으로 하였고, 상대적으로 정확도가 낮은 프로펠러유속계를 기반으로 1960년대에 관측된 자료들을 주로 활용하여 도출되었다. 따라서, 본 연구에서는 기존 ISO에서 제시한 유속-면적법에 필요한 인자들의 오차를 정밀 실규모 실험을 통해 재산정하여 기존 ISO 748과 1088에서 제시한 인자별 오차의 적정성을 검증하고자 하였다. 이를 위해 흐름을 안정적으로 통제할 수 있는 건설기술연구원 안동 하천실험센터의 완경사수로(A2)에서 정상상태의 폭 7m, 수심 1m, 유속 약 1m/s의 흐름을 유지한 후, 유속 측정 정확도가 우수한 micro-ADV를 활용하여 공간적으로 매우 정밀하게 유속을 측정하고, 수심은 Total Station을 기반으로 흐름 발생 전에 정밀 측정하였다. 오차 분석 결과, ISO 규정에서 제시한 오차와 본 실험의 결과로 도출된 인자들의 오차는 상당한 차이를 보였다. 따라서, 본 연구 결과로 도출된 유속-면적법의 인자 별 오차는 실험이 수행된 소하천 규모의 하천에서 도섭법으로 산정된 유량의 불확도를 평가할 경우에 활용될 것으로 기대된다.

• Journal of Korea Water Resources Association
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• v.50 no.8
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• pp.521-535
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• 2017

Acoustic Doppler Current Profilers (ADCPs) have been widely utilized for assessing streamflow discharge, yet few comprehensive studies were conducted to evaluate discharge uncertainty in consideration of individual uncertainty components. It could be mostly because it was not easy to determine which uncertainty framework can be appropriate to rigorously analyze streamflow discharge driven by ADCPs. In this regard, considerable efforts have been made by scientific and engineering societies to develop a standardized theoretical framework for uncertainty analysis in hydrometry. One of the well-established UA methodology based on sound statistical and engineering concepts is Guide to the Expression of Uncertainty Measurement (GUM) adopted widely by various scientific and research communities. This research fundamentally adapted the GUM framework to assess individual uncertainty components of ADCP discharge measurements, and subsequently provided results of a customized experiment in a controllable real-scale artificial river channel. We focused particularly upon sensitivities of uncertainty components in the GUM framework driven by ADCPs direct measurements such as depths, edge distance, submerged depth, velocity gap, sampling time, repeatability, bed roughness and so on. Section-by-Section method for ADCP discharge measurement was applied for uncertainty analysis for this study. All of measurements were carefully compared with data using other instrumentations such as ADV to evaluate individual uncertainty components.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.114-115
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• 2011