• 방사선산업학회지
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• 제17권4호
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• pp.471-479
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• 2023

In In-situ radioactivity measurement techniques, efficiency calibration models use predefined models to simulate a sample's geometry and radioactivity distribution. However, simplified efficiency calibration models lead to uncertainties in the efficiency curves, which in turn affect the radioactivity concentration results. This study aims to develop an efficiency calibration optimization methodology to improve the accuracy of in-situ gamma radiation measurements for byproducts from industrial facilities. To accomplish the objective, a drive mechanism for rotational measurement of an byproduct simulator and a sample was constructed. Using ISOCS, an efficiency calibration model of the designed object was generated. Then, the sensitivity analysis of the efficiency calibration model was performed, and the efficiency curve of the efficiency calibration model was optimized using the sensitivity analysis results. Finally, the radiation concentration of the simulated subject was estimated, compared, and evaluated with the designed certification value. For the sensitivity assessment of the influencing factors of the efficiency calibration model, the ISOCS Uncertainty Estimator was used for the horizontal and vertical size and density of the measured object. The standard deviation of the measurement efficiency as a function of the longitudinal size and density of the efficiency calibration model decreased with increasing energy region. When using the optimized efficiency calibration model, the measurement efficiency using IUE was improved compared to the measurement efficiency using ISOCS at the energy of ²²⁸Ac (911 keV) for the nuclide under analysis. Using the ISOCS efficiency calibration method, the difference between the measured radiation concentration and the design value for each simulated subject measurement direction was 4.1% (1% to 10%) on average. The difference between the estimated radioactivity concentration and the design value was 3.6% (1~8%) on average when using the ISOCS IUE efficiency calibration method, which was closer to the design value than the efficiency calibration method using ISOCS. In other words, the estimated radioactivity concentration using the optimized efficiency curve was similar to the designed radioactivity concentration. The results of this study can be utilized as the main basis for the development of regulatory technologies for the treatment and disposal of waste generated during the operation, maintenance, and facility replacement of domestic byproduct generation facilities.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.19-19
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• 2011

The appraisals of hydrology model behavior for flow and water quality are generally performed through comparison of simulated data with observed ones. To perform appraisal of hydrology model, some criteria are often used, such as coefficient of determination ($R^2$), Nash and Sutcliffe model efficiency coefficient (NSE), index of agreement (d), modified forms of NSE and d, and relative efficiency criteria NSE and d. These criteria are used not only for hydrology model estimations also for various comparisons of two data sets; This NSE has been often used for SWAT calibration. However, it has been known that the NSE value has some limitations in evaluating hydrology at watersheds under monsoon climate because this statistic is largely affected by higher values in the data set. To overcome these limitations, the SWAT auto-calibration module was enhanced with K-means clustering and direct runoff/baseflow modules. However the NSE is still being used in this module to evaluate model performance. Therefore, the SWAT Auto-calibration module was modified to incorporate alternative efficiency criteria into the SWAT K-means/direct runoff-baseflow auto-calibration module. It is expected that this enhanced SWAT auto-calibration module will provide better calibration capability of SWAT model for all flow regime.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.695-698
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• 2021

Efficiency calibration is a fundamental procedure in gamma spectrometric measurement. Experimental technique for efficiency calibration transfer in gamma spectrometer along different geometries and volumes has been developed and validated in this work. The developed technique offers simple and easy procedures to overcome several problems encountered in efficiency calibration of gamma spectrometer such as rate-related correction and different sample volumes. The validation shows that application of the developed technique has a precision of 95%.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.137-142
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• 2018

Background: Gamma-ray detectors having a thin window of a material with low atomic number can increase the true coincidence summing effects for radionuclides emitting X-rays or gamma-rays. This effect can make efficiency calibration or spectrum analysis more complicated. In this study, a Cu shield was tested as an X-ray filter to neglect the true coincidence summing effect by X-rays and gamma-rays in gamma-ray spectrometry, in order to simplify gamma-ray energy spectrum analysis. Materials and Methods: A Cu shield was designed and applied to an n-type high-purity germanium detector having an $X-{\gamma}$ summing effect during efficiency calibration. This was tested using a commercial, certified mixed gamma-ray source. The feasibility of a Cu shield was evaluated by comparing efficiency calibration results with and without the shield. Results and Discussion: In this study, the thickness of a Cu shield needed to avoid true coincidence summing effects due to $X-{\gamma}$ was tested and determined to be 1 mm, considering the detection efficiency desired for higher energy. As a result, the accuracy of the detection efficiency calibration was improved by more than 13% by reducing $X-{\gamma}$ summing. Conclusion: The $X-{\gamma}$ summing effect should be considered, along with ${\gamma}-{\gamma}$ summing, when a detection efficiency calibration is implemented and appropriate shielding material can be useful for simplifying analysis of the gamma-ray energy spectra.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3833-3840
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• 2022

A method for calibrating the energy scale and detection efficiency of stilbene scintillators is presented herein. This method can be used to quantitatively analyze the Compton continuum of gamma-ray spectra obtained using such scintillators. First, channel-energy calibration was conducted by fitting a semi-empirical equation for the Compton continuum to the acquired energy spectrum and a new method to evaluate the intrinsic detection efficiency, called intrinsic Compton efficiency, of stilbene scintillators was proposed. The validity of this method was verified by changing experimental conditions such as the number of sources being measured simultaneously and the detector-source distance. According to the energy calibration, the standard error for the estimated Compton edge position was ±1.56 keV. The comparison of the intrinsic Compton efficiencies calculated from the single- and two-source spectra showed that the mean absolute difference and the mean absolute percentage difference are 0.031 %p and 0.557%, respectively, demonstrating reasonable accuracy of this method. The feasibility of the method was confirmed for an energy range of 0.5-1.5 MeV, showing that stilbene scintillators can be used to quantitatively analyze gamma rays in mixed-radiation fields.

• 전자공학회논문지B
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• 제29B권2호
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• pp.27-39
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• 1992

3 Dimensional measurement system using camera and laser slit-ray is studied. Precise calibration technique in this system is suggested. Calibration is accomplished with calibration die, calibration block and robot. For obtaining calibration parameters, the equations are solved using least square error method from a great many calibration points to reduce measuring error. Continuous measurement is possible for the object which is larger than one frame of camera. The efficiency and usability are proved by applying to the tire profile measuring system which measures tire profile using robot and this system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.269-272
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• 2003

Industry is now seeing a dramatic increase in robot simulation and off-line programming. In order to use off-line programming effectively, the simulated workcell has to be identical to the real workcell. This requires an efficient and accurate method for the workcell calibration. Currently used techniques in the industry, however, are typically time-consuming, expensive and therefore not suitable for in-process application. This is because most of these techniques are based on the so-called “absolute calibration” method. In contrast to absolute method, relative calibration only measures the difference of an interested object relative to a standard reference. Owing to the small measurement range requirement, relative calibration method is very cheap and can achieve very high accuracy. In this paper the relative method is applied to calibrate an entire grinding workcell. Linear gauge is the only measurement device used. This workcell calibration includes tool center point (TCP) calibration and work object frame calibration. Due to the efficiency of the calibration algorithm and the simplicity of the calibration setup, the described calibration procedure can be done in process.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.526-532
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• 2019

In this study, an in-house $^{152}Eu$ calibration source was produced from a custom epoxy matrix with a density of ${\rho}=1.14g\;cm^{-3}$, which is chemically stable and durable form after its solidification. The homogeneity of $^{152}Eu$ in matrix was obtained better than 98%. For a Marinelli beaker geometry, an efficiency calibration procedure was applied to a n-type, coaxial, 78.5% relative efficient HPGe detector in the energy range of 121.7-1408.0 keV by using in-house $^{152}Eu$ calibration source. Then the measured efficiencies for Marinelli geometry were compared with the results calculated by MEFFTRAN and ANGLE softwares for the validation. Although MEFFTRAN and ANGLE have two different efficiency transfer algorithms to calculate the efficiencies, they usually need to use a reliable and accurate reference efficiency values as input data. Hence, reference efficiency values were obtained experimentally from a multinuclide standard source for the same detector-Marinelli geometry. In the present source characterization, the corrections required for self-absorption and true coincidence summing effects for $^{152}Eu$ gamma-rays were also obtained for a such close counting geometry condition. The experimental results confirmed the validity of efficiency calculations obtained by MEFFTRAN and ANGLE softwares that are calculation tools.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.368-377
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• 2009

In this paper we study the gyro bias calibration method of SDINS(Strap-Down Inertial Navigation System). Generally, SDINS's calibration is performed in 2-axis(or 3-axis) rate table with chamber for varying ambient temperature. We assumed that the majority of calibration-parameter except for gyro bias is knowned. During gyrobias calibration procedure, it can be induced some disturbances(accelerometer's short-term error induced rate table rotation and anti-vibration mount's rotation). In these cases, old gyro-bias calibration methods(using velocity error or attitude error) have an error, because these disturbances are not detectable at the same time. So that, we propose a new gyro-bias calibration method(heading error minimizing using equivalent linear transformation) that can detect anti-vibration mount's rotation. And we confirm efficiency of the new gyro-bias calibration method by simulation.

• 한국농공학회논문집
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• 제60권1호
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• pp.11-20
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• 2018

This study is to calibrate the SWAT (Soil and Water Assessment Tool) water quality of SS (Suspended Solid), T-P (Total Phosphorus), and T-N (Total Nitrogen) by focusing on 2014~2015 drought periods and identify the important parameters. For Gongdo watershed ($366.5km^2$), the SWAT was calibrated for 2 cases of 2002~2006 normal year focusing calibration and 2014~2015 drought focusing calibration respectively. The parameters of N_UPDIS (Nitrogen uptake distribution parameter) and CMN (Rate factor for humus mineralization of active organic nutrients) played important roles for T-N calibration during drought periods. The SWAT SS, T-N, and T-P average $R^2$ (Coefficient of determination) results by focusing on 2014~2015 drought periods calibration showed 0.71, 0.65 and 0.62 while 2002~2006 normal year focusing calibration showed 0.63, 0.58 and 0.50 respectively. Also SWAT SS, T-N, and T-P model efficiency NSE (Nash-Sutcliffe efficiency) results by focusing on drought period (2014~2015) calibrated showed 0.76, 0.77, 0.87 respectively. Even though the SS, T-P parameters were unchanged during the calibration, the SS and T-P results were improved by the hydrological parameters (SCS-CN, SOL_K, SLSOIL) during the drought periods. The SWAT water quality calibration needs to be considered for the movement of SS and nutrients transport especially focusing on the drought characteristics.