• Structural Engineering and Mechanics
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• 제83권5호
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• pp.577-591
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• 2022

This paper develops a comparatively time-efficient methodology for performing seismic fragility analysis of the reinforced concrete (RC) buildings in the presence of uncertainty sources. It aims to appraise the effectiveness of any variation in the material's mechanical properties as epistemic uncertainty, and the record-to-record variation as aleatory uncertainty in structural response. In this respect, the fuzzy set theory, a well-known 𝛼-cut approach, and the Genetic Algorithm (GA) assess the median of collapse fragility curves as a fuzzy response. GA is requisite for searching the maxima and minima of the objective function (median fragility herein) in each membership degree, 𝛼. As this is a complicated and time-consuming process, the authors propose utilizing the Gene Expression Programming-based (GEP-based) equation for reducing the computational analysis time of the case study building significantly. The results indicate that the proposed structural analysis algorithm on the derived GEP model is able to compute the fuzzy median fragility about 33.3% faster, with errors less than 1%.

• 분석과학
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• 제16권6호
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• pp.475-482
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• 2003

혈액 시료 중의 다이옥신 농도를 분석하는 과정에서 있을 수 있는 중요한 오차요인들을 고려하여 최종적인 측정 결과에 대한 불확도를 구하였다. 불확도의 평가 원리는 측정 불확도 표현 지침서를 따랐으며, 불확도를 구하는 방법도 이 지침서를 참고하여 수행되었다. 각 측정 과정의 불확도 요인을 고려하여 다이옥신 및 퓨란의 주요 17가지 이성질체 중 이 실험에서 농도가 검출된 11가지 이성질체에 한하여 각각에 대한 불확도를 구한 후, 이 값들을 합성하여 총 다이옥신 농도에 대한 불확도를 구하였다. 이렇게 하여 얻은 불확도를 함께 나타낸 최종 다이옥신 농도는 $0.0746{\pm}0.0074pg$ I-TEQ/g weight 또는 $20.68{\pm}2.04pg$ I-TEQ/g lipid 이었다. 전자는 시료의 무게당 환산농도로 나타낸 것이며, 후자는 지방의 무게당 환산농도로 나타낸 것이다. 이와 같이, 측정 결과에 대한 불확도를 구하여 측정량의 존재 범위를 나타냄으로써 분석 결과의 품질을 정량적으로 보증할 수 있다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.194-194
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• 2002

• Current Optics and Photonics
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• 제4권6호
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• pp.509-515
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• 2020

A practical single photon source for fiber-based quantum information processing is still lacking. As a possible 1.55-㎛ quantum-dot single photon source, an InGaAsP/InP-air-aperture micropillar cavity is investigated in terms of fabrication tolerance. By properly modeling the processing uncertainty in layer thickness, layer diameter, surface roughness and the cavity shape distortion, the fabrication imperfection effects on the cavity quality are simulated using a finite-difference time-domain method. It turns out that, the cavity quality is not significantly changing with the processing precision, indicating the robustness against the imperfection of the fabrication processing. Under thickness error of ±2 nm, diameter uncertainty of ±2%, surface roughness of ±2.5 nm, and sidewall inclination of 0.5°, which are all readily available in current material and device fabrication techniques, the cavity quality remains good enough to form highly efficient and coherent 1.55-㎛ single photon sources. It is thus implied that a quantum dot contained InGaAsP/InP-air-aperture micropillar cavity is prospectively a practical candidate for single photon sources applied in a fiber-based quantum information network.

• 산업경영시스템학회지
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• 제45권4호
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• pp.31-41
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• 2022

As the environmental impacts of fossil fuel energy sources increase, the South Korean government has tried to change non-environmental-friendly enery sources to environmental-friendly energy sources in order to mitigate environmental effects, which lead to global warming and air pollution. With both a limited budget and limited time, it is essential to accurately evaluate the economic and environmental effects of renewable energy projects for the efficient and effective operation of renewable energy plants. Although the traditional economic evaluation methods are not ideal for evaluating the economic impacts of renewable energy projects, they can still be used for this purpose. Renewable energy projects involve many risks due to various uncertainties. For this reason, this study utilizes a real option method, the Geske compound model, to evaluate the renewable energy projects on Jeju Island in terms of economic and environmental values. This study has developed an economic evaluation model based on the Geske compound model to investigate the influences of flexibility and uncertainty factors on the evaluation process. This study further conducts a sensitivity analysis to examine how two uncertainty factors (namely, investment cost and wind energy production) influence the economic and environmental value of renewable energy projects.

• 대한기계학회논문집A
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• 제34권1호
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• pp.73-78
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• 2010

재료의 인장 물성 측정 불확도 평가가 수행되었다. 인장 물성 측정에 영향을 주는 불확도의 요인이 구분되어 분석되었고 인장 시험으로부터 측정되는 측정량, 즉 탄성계수, 항복 강도 그리고 인장 강도의 불확도 평가 모델이 본 연구에서 제시되었고 각 측정량에 대한 대응하는 수학적 모델과 측정치로부터 각 측정치의 감도계수를 계산함으로서 유도 되었다. 각 모델에 근거하여 ISO 6892에 따라 결정되는 SUS316LN의 실험적 데이터로부터 인장 물성의 불확도가 평가되었다.

• International Journal of Aeronautical and Space Sciences
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• 제8권2호
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• pp.126-131
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• 2007

In this paper, Monte Carlo Simulation (MCS) method was used as an uncertainty assessment tool for air flow, net thrust measurement. Uuncertainty sources of the net thrust measurement were analyzed, and the probability distribution characteristics of each source were discussed. Detailed MCS methodology was described including the effect of the number of simulation. Compared to the conventional sensitivity coefficient method, the MCS method has advantage in the uncertainty assessment. The MCS is comparatively simple, convenient and accurate, especially for complex or nonlinear measurement modeling equations. The uncertainty assessment result by MCS was compared with that of the conventional sensitivity coefficient method, and each method gave different result. The uncertainties in the net thrust measurement by the MCS and the conventional sensitivity coefficient method were 0.906% and 1.209%, respectively. It was concluded that the first order Taylor expansion in the conventional sensitivity coefficient method and the nonlinearity of model equation caused the difference. It was noted that the uncertainty assessment method should be selected carefully according to the mathematical characteristics of the model equation of the measurement.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.331-343
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• 2019

Dynamic thermal rating of the overhead transmission lines is affected by many uncertain factors. The ambient temperature, wind speed and wind direction are the main sources of uncertainty. Measurement uncertainty is an important parameter to evaluate the reliability of measurement results. This paper presents the uncertainty analysis based on Monte Carlo. On the basis of establishing the mathematical model and setting the probability density function of the input parameter value, the probability density function of the output value is determined by probability distribution random sampling. Through the calculation and analysis of the transient thermal balance equation and the steady- state thermal balance equation, the steady-state current carrying capacity, the transient current carrying capacity, the standard uncertainty and the probability distribution of the minimum and maximum values of the conductor under 95% confidence interval are obtained. The simulation results indicate that Monte Carlo method can decrease the computational complexity, speed up the calculation, and increase the validity and reliability of the uncertainty evaluation.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.436-439
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• 2000

To interact with surroundings robots and other automated machines employ sensors. However, the sensors measurements are uncertain in some amount and this may limit the potential applications of machines. Varying surrounding conditions and noises of sensor signals are major sources of the uncertainty. In this paper the uncertainty is tried to be reduced by using redundant sensor systems, where the redundancy is accomplished by varying the parameters of logically defined sensors. The target value redundantly measured is estimated adaptively. An experiment was done for measuring the stereoscopic 3D position measurement in an inconsistent light condition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.576-576
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• 2013

Recently, diagnostics of plasma becomes more important due to requirement of precise control of plasma processing based on measurement of plasma characteristics. The Langmuir probe has been used for the diagnostics but it has an inevitable uncertainty and error sources such as incorrect tip length and RF noise. Instead of the Langmuir probe, various diagnostic methods have been developed and researched. The cutoff probe is promising one for plasma density using microwaves and resonance phenomenon at the plasma frequency. The cutoff probe has various advantages as follows; (i) it is simple and robust, (ii) it uses few assumptions, and (iii) it is free from deposition by reactive gas. However, the cutoff probe also has uncertainty and error sources such as gap between tips, tip length, direction of tip plane, and RF noise. In this study, the uncertainty and error sources in manufacturing both probes and in diagnostics process were analyzed via comparative experiment at various discharge conditions. Furthermore, to reveal the user dependence of both probes, three well trained Ph. D students made the Langmuir probe and the cutoff probe, respectively, and it were analyzed. Thought this study, it is established that reliability and validity of the Langmuir probe and the cutoff probe related with not only the intrinsic characteristics of probes but also probe user.