• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.24-29
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• 2004

The inter-comparison of standards is required to be recognized the calibration results. The sonic nozzle package is developed to do inter-comparison of the bell preyer used to calibrate many gas flow meters for industries. Four national metrology institutes (KRISS, CMS, CENAM, NEL) were participated in this inter-comparison. The deviation of calibration data from the average value was small at the low flow rate and large at the high flow rate, respectively At the high flow rate, the deviation was larger than the expected value from uncertainties asserted by NMIs. This means there are some problems in the uncertainty evaluation and experiment procedures in some of the participated NMIs.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.765-777
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• 2011

According to the total pollution load management system, exact prediction and analysis of water quality and discharge has been required in order to allocate the amount of pollution load to each local government. In this study, QUAL2E model was used for comparison with other water quality models and improve the inadequate to forecast future water quality. And Various calibration and verification methods were applied to deal with existing uncertainties of parameter during modeling water quality. For user convenience, A GUI(Graphical User Interface) system named "QL2-XP" model is developed by object-oriented language for the user convenience and practical usage. Suggested GUI system consist of hydraulic analysis, water quality analysis, optimized model calibration processes, and postprocessing the simulation results. Therefore this model will be effectively utilized to manage practical and efficient water quality.

• Journal of the Korean Society of Tobacco Science
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• v.23 no.1
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• pp.45-52
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• 2001

This study was carried out to evaluate the uncertainty in the analysis of total alkaloids and reducing sugar content in flue-cured tobacco. The sources of uncertainty associated with the analysis of total alkaloids and reducing sugar were the weighing of sample, the preparation of extracting solution, the addition of extracting solution into the sample, the preparation of standard solution, the precision of calibration curve for standard solution, the reproducibility of analysis, and the determination of water content in tobacco, etc. For the calculating uncertainties, Type A of uncertainty was evaluated by the statistical analysis of a series of observation, and Type B by the information based on supplier’s catalogue and/or certificated of calibration. It was shown that the main source of uncertainty was caused by the calibration curve of standard solution, the reproducibility of analysis, the volume measurement of 1$m\ell$, and the purity of nicotine reference material in the preparation of standard solution. The uncertainty in the addition of extracting solution, the sample weighing, the volume measurement of 100$m\ell$, and the determination of water content of tobacco contributed relatively little to the overall uncertainty. The expanded uncertainty of total alkaloids and reducing sugar in flue-cured tobacco at 95% level of confidence was $\pm$0.12% and $\pm$0.54%, respectively.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.35.1-35.1
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• 2021

RR Lyrae stars are sensitive probe for the precision stellar astrophysics and also for the cosmic distance scale thanks to their well-defined near-infrared Period-Luminosity relations (PLRs). These horizontal branch variables can be used for primary calibration of the first-rung of population II distance ladder providing an evaluation of the ongoing tension between Cepheid-Supernovae based Hubble constant and the Planck results. Therefore, absolute calibration of RR Lyrae PLRs is now crucial to complement or test the tip of the red giant branch based distances, and in turn, population II star based Hubble constant measurements. While the pulsation models of RR Lyrae can reproduce most observables, they predict a significant metallicity effect on their JHKs-band PLRs that is inconsistent with so-far limited observational studies. We remedy this inconsistency of metallicity dependence in RR Lyrae PLRs by combining their near-infrared observations in the globular clusters of different mean-metallicities with the new parallaxes from the Gaia early data release 3 (EDR3). Our empirical results on Period-Luminosity-Metallicity (PLZ)relations are consistent with theoretical predictions but the precision of absolute calibrations is still affected by the parallax uncertainties and the systematic zero-point offset present in the Gaia EDR3.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.246-254
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• 2006

A computation program has been developed for automatic data processing in the calibration process of gamma survey meter. The automatic processing program has been developed based on Visual Basic. The program has been coded according to steps of calibration procedure. The OLE(object linking an embedding) Excel automation method fur automatic data processing is used in this program, which is a kind of programming technique for the Excel control. The performance test on the basis of reference data has been carried out by using the developed program. In the results of performance test, the values of calibration factors and uncertainties by the developed program were equal to those obtained from the reference data. In addition, It was revealed that the efficiency and precision of working are significantly increased by using the developed program.

• Proceedings of the KSRS Conference
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• v.1
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• pp.86-89
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• 2006

Ocean color remote sensing community currently uses the different solar irradiance spectra covering the visible and near-infrared in the calibration/validation and deriving products of ocean color instruments. These spectra derived from single and / or multiple measurements sets or models have significant discrepancies, primarily due to variation of the solar activity and uncertainties in the measurements from various instruments and their different calibration standards. Thus, it is prudent to examine model-to-model differences and select a standard reference spectrum that can be adopted in the future calibration and validation processes, particularly of the first Geostationary Ocean Color Imager (GOCI) onboard its Communication Ocean and Meterological Satellite (COMS) planned to be launched in 2008. From an exhaustive survey that reveals a variety of solar spectra in the literature, only eight spectra are considered here seeing as reference in many remote sensing applications. Several criteria are designed to define the reference spectrum: i.e., minimum spectral range of 350-1200nm, based completely or mostly on direct measurements, possible update of data and less errors. A careful analysis of these spectra reveals that the Thuillier 2004 spectrum seems to be very identical compared to other spectra, primarily because it represents very high spectral resolution and the current state of the art in solar irradiance spectra of exceptionally low uncertainty ${\sim}0.1%.$ This study also suggests use of the Gueymard 2004 spectrum as an alternative for applications of multispectral/multipurpose satellite sensors covering the terrestrial regions of interest, where it provides spectral converge beyond 2400nm of the Thuillier 2004 spectrum. Since the solar-activity induced spectral variation is about less than 0.1% and a large portion of this variability occurs particularly in the ultraviolet portion of the electromagnetic spectrum that is the region of less interest for the ocean color community, we disregard considering this variability in the analysis of solar irradiance spectra, although determine the solar constant 1366.1 $Wm^{-2}$ to be proposed for an improved approximation of the extraterrestrial solar spectrum in the visible and NIR region.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.405-412
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• 2020

The thermistor mount is used for precise RF power measurement because the calibration factor is constant according to the change of power. The calibration factor of the standard mount can be measured with an uncertainty less than 0.5 % from the 10 MHz to 1 GHz by direct comparison with the transfer standard using the DC substitution method. Recently, as the supply of precision power meter based on DC substitution method allows simple and fast measurement, a simple direct comparison measurement system with the same level uncertainty was designed and the minimum required specifications of components through analysis of mismatch error was proposed. The uncertainty was evaluated for system validation, and the results show that uncertainties have been well maintained within 0.5 % in the measurement frequencies.

• Steel and Composite Structures
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• v.7 no.6
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• pp.487-502
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• 2007

In recent decades there has been a trend towards improved mechanical characteristics of materials used in footbridge construction. It has enabled engineers to design lighter, slender and more aesthetic structures. As a result of these construction trends, many footbridges have become more susceptible to vibrations when subjected to dynamic loads. In addition to this, some inherit modelling uncertainties related to a lack of information on the as-built structure, such as boundary conditions, material properties, and the effects of non-structural elements make difficult to evaluate modal properties of footbridges, analytically. For these purposes, modal testing of footbridges is used to rectify these problems after construction. This paper describes an arch type steel footbridge, its analytical modelling, modal testing and finite element model calibration. A modern steel footbridge which has arch type structural system and located on the Karadeniz coast road in Trabzon, Turkey is selected as an application. An analytical modal analysis is performed on the developed 3D finite element model of footbridge to provide the analytical frequencies and mode shapes. The field ambient vibration tests on the footbridge deck under natural excitation such as human walking and traffic loads are conducted. The output-only modal parameter identification is carried out by using the peak picking of the average normalized power spectral densities in the frequency domain and stochastic subspace identification in the time domain, and dynamic characteristics such as natural frequencies mode shapes and damping ratios are determined. The finite element model of footbridge is calibrated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain modelling parameters such as material properties. At the end of the study, maximum differences in the natural frequencies are reduced from 22% to only %5 and good agreement is found between analytical and experimental dynamic characteristics such as natural frequencies, mode shapes by model calibration.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.681-690
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• 2013

Watershed models have been increasingly used to support an integrated management of land and water, non-point source pollutants, and implement total daily maximum load policy. However, these models demand a great amount of input data, process parameters, a proper calibration, and sometimes result in significant uncertainty in the simulation results. For this reason, uncertainty analysis is necessary to minimize the risk in the use of the models for an important decision making. The objectives of this study were to evaluate three different uncertainty analysis algorithms (SUFI-2: Sequential Uncertainty Fitting-Ver.2, GLUE: Generalized Likelihood Uncertainty Estimation, ParaSol: Parameter Solution) that used to analyze the sensitivity of the SWAT(Soil and Water Assessment Tool) parameters and auto-calibration in a watershed, evaluate the uncertainties on the simulations of runoff and sediment load, and suggest alternatives to reduce the uncertainty. The results confirmed that the parameters which are most sensitive to runoff and sediment simulations were consistent in three algorithms although the order of importance is slightly different. In addition, there was no significant difference in the performance of auto-calibration results for runoff simulations. On the other hand, sediment calibration results showed less modeling efficiency compared to runoff simulations, which is probably due to the lack of measurement data. It is obvious that the parameter uncertainty in the sediment simulation is much grater than that in the runoff simulation. To decrease the uncertainty of SWAT simulations, it is recommended to estimate feasible ranges of model parameters, and obtain sufficient and reliable measurement data for the study site.

• Analytical Science and Technology
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• v.19 no.6
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• pp.553-558
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• 2006

In this study, an attempt was made to measure uncertainties involved in the VOC analysis for the VOC working standards prepared by a dilution technique using Tedlar bags. For this purpose, VOC standard gases of benzene, toluene, xylene, and styrene were prepared at four different concentrations (4, 8, 20, and 40 ppb). These standard samples were then loaded on to the GC system equipped with air server/thermal desorption (AS/TD) system. Each of these four standard concentrations was analyzed individually to derive their respective calibration results. These calibration data sets were then compared across four different compounds. According to this comparison, differences in calibration patterns were moderately insignificant within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard was fairly high compared to other VOCs investigated simultaneously. The results of our study suggest that the analytical uncertainty associated with the preparation of VOC starndard gas using a dilution technique can be assessed in a fairly reasonable manner for samples with a narrow concentration range.