• 한국유체기계학회 논문집
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• 제14권1호
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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.

• 부모자녀건강학회지
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• 제17권1호
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• pp.29-36
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• 2014

Purpose: Competence in parenting helps the parent to recognize the ability to resolve problems arising to children, allowing positive interactions with children through desirable child-rasing behavior and smooth communication with children. This study aims to identify the contribution of uncertainty and educational needs to the competence in parenting. Methods: Total 159 mothers responded a questionnaire developed to measure uncertainty, educational needs, and competence in parenting. t-test, ANOVA, and stepwise multiple regression with the SPSS program were used to analyze the data. Results: We found that uncertainty, nursing educational need, and mothers' age had influence to the competence in parenting. Conclusion: Nursing interventions provided to the mothers of hospitalized children for better parental competence need to include programs for alleviating uncertainty and satisfying the need for nursing education.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.689-698
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• 2004

Uncertainties generated from the individual measured variables have an influence on the uncertainty of the experimental result through a data reduction equation. In this study, a performance test of a single stage axial type turbine is conducted, and total-to-total efficiencies are measured at the various off-design points In the low pressure and cold state. Based on an experimental apparatus, a data reduction equation for turbine efficiency is formulated and six measured variables are selected. Codes are written to calculate the efficiency, the uncertainty of the efficiency, and the sensitivity of the efficiency uncertainty by each of the measured quantities. The influence of each measured variable on the experimental result is figured out. Results show that the largest uncertainty magnification factor (UMF) value is obtained by the inlet total pressure among the six measured variables, and its value is always greater than one. The UMF values of the inlet total temperature, the torque, and the RPM are always one. The uncertainty percentage contribution (UPC) of the RPM shows th, lowest influence on the uncertainty of the turbine efficiency, but the UPC of the torque has the largest influence to the result among the measured variables. These results are applied to find the correct direction for meeting an uncertainty requirement of the experimental result in the planning or development Phase of experiment, and also to offer ideas for preparing a measurement system in the planning phase.

• 분석과학
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• 제27권6호
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• pp.269-276
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• 2014

후 컬럼 동위원소 희석법의 불확도를 HPLC-ICP/MS에서 Selenomethionine을 분석할 경우에 대하여 간단히 연구하였다. 주요하다고 생각한 오차의 원인으로 셀레늄 동위원소 용액의 농도와 흐름속도, 스파이크 용액과 시료 용액에서의 셀레늄 원자량, 그리고 스파이크된 시료용액에서 측정된 동위원소의 비를 선택하였다. 각 요인에 따른 불확도를 구하고 전체 농도의 불확도에 미치는 요인을 계산한 결과, 각각에 대하여 54.4%와 0.61%, 0.0072%와 0.018%, 그리고 45.0%를 얻었다. 가장 큰 요인은 스파이크 동위원소 용액의 농도이며 두 번째는 스파이크가 첨가된 시료용액에서의 동위원소비이었다. 스파이크 용액의 질량흐름속도와 원자량의 불활도는 크게 영향을 끼치지 못하였다. 계산된 전체불확도는 $126.30ng{\cdot}g^{-1}$ SeMet 표준용액에 대하여 $1.46ng{\cdot}g^{-1}$으로서 실험결과는 $127.09ng{\cdot}g^{-1}$을 얻었고 상대불확도는 1.20%이었다.

• 한국정밀공학회지
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• 제15권11호
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• pp.67-75
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• 1998

Geometric and thermal errors are key contributors to the errors of a computer numerically controlled turning center. A planar error synthesis model is obtained by synthesizing 11 geometric and thermal error components of a turning center with homogeneous coordinate transformation method. This paper shows the sensitivity analysis on the temperature change, the confidence evaluation on the uncertainty Of measurement systems, and the error contribution analysis from the planar error synthesis model. Planar error in the z direction was very sensitive to the temperature change. and planar errors in the x and z directions were not affected by the uncertainty of measurement systems. The error contribution analysis ,which is applicable to designing a new turning center, was helpful to find the large error components which affect planar errors of the turning center.

• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.109-128
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• 2020

A climate-impact projection usually consists of several stages, and the uncertainty of the projection is known to be quite large. It is necessary to assess how much each stage contributed to the uncertainty. We call an uncertainty quantification method in which relative contribution of each stage can be evaluated as uncertainty decomposition. We propose a new Bayesian model for uncertainty decomposition in climate change impact assessments. The proposed Bayesian model can incorporate uncertainty of natural variability and utilize data in control period. We provide a simple and efficient Gibbs sampling algorithm using the auxiliary variable technique. We compare the proposed method with other existing uncertainty decomposition methods by analyzing streamflow data for Yongdam Dam basin located at Geum River in South Korea.

• 대한기계학회논문집B
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• 제38권7호
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• pp.625-638
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• 2014

본 연구에서는 천연가스 유량 측정에 사용되는 임계유동함수(CFF)를 AGA8-dc 상태방정식으로 계산할 때 CFF 계산값의 불확도를 평가하였다. CFF 계산에 사용되는 엔탈피, 엔트로피, 음속 식은 불확도 분석이 가능하도록 무차원 헬름홀츠 자유에너지(Helmholtz free energy, HFE)와 이의 편도함수로 표현하였고, HFE의 불확도를 추정하였다. 압축인자의 불확도에 의해 유발되는 종속 변수의 불확도를 반영하기 위해 AGA8-dc 압축인자 식을 해당 불확도만큼 편차가 생기는 형태로 변형하였고, 각 불확도 요인별로 불확도 기여도 평가 모델을 만들었으며, 이를 CFF 계산 프로그램에 적용하였다. 그 결과 CFF의 불확도는 압력 10, 50, 100 bar 에서 각각 0.025, 0.055, 0.112 % 정도로 평가 되었고 압력에 비례하여 증가하는 것을 확인하였다. 또한 본 결과를 기존 CFF 국제비교시험결과(1999년)에 적용한 결과 각 기관별 CFF 값의 차이를 적절히 설명하는 것도 알 수 있었다.

• 대한기계학회논문집B
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• 제24권10호
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• pp.1388-1398
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• 2000

A pipe prover is a flowmeter calibrator used in flow measurement field. Gravimetric and volumetric methods were applied to determine the basic volume of the pipe prover. Uncertainty of its basic volume measurement was evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainty of determining the basic volume was estimated from the sensitivity coefficient and the standard uncertainty of independent variables. It was found that the uncertainties of the weighing and volume measurements have dominant influence on that of the basic volume determination. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of the basic volume is shown clearly.

• 대한기계학회논문집B
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• 제25권4호
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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.

• 한국시스템다이내믹스학회:학술대회논문집
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• 한국시스템다이내믹스학회 2004년도 춘계 학술대회 발표논문집
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• pp.109-128
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• 2004

A system dynamics model is developed in order to evaluate the contribution level of the activities regarding HANARO, which is the research reactor in Korea. The system dynamics model has room to be improved, but it is logically sound enough to evaluate the general level of contributions and to develop strategies for the HANARO to be more contributable. Considering the uncertainty involved with the input variables, the contribution level is ranged from 3 times to about 30 times of the investment made on it. The evaluation results can be summarized as follows : (Table Omitted).