• 한국의학물리학회지:의학물리
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• 제30권2호
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• pp.59-63
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• 2019

Purpose: To manage radiation measurement equipment, a web-based management program has been developed in this study. Materials and Methods: This program is based on a web service and Java Server Pages (JSP) and employs compatibility and accessibility. Results: The first step in the workflow has been designed to create accounts for each user or organization and to log in. The program consists of two parts: fields for listed instruments, and measurement information. The instruments for measuring radiation listed in this program are as follows: ionization chambers, survey meters, thermometers, barometers, electrometers, and phantoms. Instrument properties can be put in the recording fields and browsing for associated instruments can be performed. The main part of the program is the cross-calibration for each ion chamber. For instance, the ionization chamber to be used as a relative dosimeter can be registered by cross-calibration data with a reference chamber calibrated by an accredited laboratory. This program supports methods using the central axis transfer theory for cross-calibration for the ionization chambers. The reference and field ionization chambers were placed in a solid water phantom along the beam central axis at two different depths, and then the positions were switched. Each measured value was used for calculating the cross-calibration factor. Conclusions: Because many instruments are used and managed in radiation oncology departments, systematic, traceable recording is very important. The web-based program developed in this study is expected to be used effectively in the maintenance of radiation measurement instruments.

• 한국농공학회논문집
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• 제61권5호
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• pp.69-77
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• 2019

The objective of this study was to calibrate and validate the HSPF (Hydrological Simulation Program-Fortran) model for estimating the runoff of the Hapcheon dam watershed. Spatial data, such as watershed, stream, land use, and a digital elevation map, were used as input data for the HSPF model. Observed runoff data from 2000 to 2016 in study watershed were used for calibration and validation. Hydrologic parameters for runoff calibration were selected based on the user's manual and references, and trial and error method was used for parameter calibration. The $R^2$, RMSE (root-mean-square error), RMAE (relative mean absolute error), and NSE (Nash-Sutcliffe efficiency coefficient) were used to evaluate the model's performance. Calibration and validation results showed that annual mean runoff was within ${\pm}4%$ error. The model performance criteria for calibration and validation showed that $R^2$ was in the rang of 0.78 to 0.83, RMSE was 2.55 to 2.76 mm/day, RMAE was 0.46 to 0.48 mm/day, and NSE was 0.81 to 0.82 for daily runoff. The amount of inflow to Hapcheon Dam was calculated from the calibrated HSPF model and the result was compared with observed inflow, which was -0.9% error. As a result of analyzing the relation between inflow and storage capacity, it was found that as the inflow increases, the storage increases, and when the inflow decreases, the storage also decreases. As a result of correlation between inflow and storage, $R^2$ of the measured inflow and storage was 0.67, and the simulated inflow and storage was 0.61.

• 분석과학
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• 제19권6호
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• pp.490-497
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• 2006

액화 천연가스(LNG) 공정 분석 결과의 불확도 요인을 평가하였다. 평가된 불확도 요인은 측정 반복성, 사용된 GC의 비 직선성, 사용된 표준가스의 불확도, 시료 채취 방법에 따른 농도 변화 그리고 교정 후의 기기 변동이었으며, 이 중에서 중요한 불확도 요인은 사용된 GC의 비 직선성, 사용된 표준가스의 불확도 그리고 교정 후의 기기 변동이었다. 주요 성분인 메탄 및 에탄의 경우, 각각 $90.0{\pm}0.9%mol/mol$(확장불확도, 95% 신뢰 수준) 및 $6.26{\pm}0.08%mol/mol$(확장불확도, 95% 신뢰 수준)이었다. 가스 성분원소별로 각 불확도 요소의 기여 정도는 차이가 있었고, 메탄 분석의 경우 사용된 GC의 비 직선성의 상대 표준불확도가 0.28%, 사용된 표준가스의 상대 표준불확도가 0.25%, 그리고 교정 후의 기기 변동에 의한 상대 표준불확도가 0.24%이었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1175-1182
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• 2005

Using KUCCS, which enables real-time monitoring and controlling, the various boundary condition and in-situ field stress condition was simulated, to derive the correlation among ${{\sigma}_v}'-Dr-N$in domestic sandy soils. Soil specimens, having various relative density and confined stress, were formulated to evaluate N-value from the SPT. and Pile Driving Analyzer, PDA, was employed as a measuring device for the energy transfer efficiency in the rod. From the quantitative analysis of N-value, the correlating equation, $N_{60}/{D_r}^2=16.35+14.45{{\sigma}_v}'$ was obtained on the basis of Skempton's method(1986). More reliable soil parameters can be obtained from the N-value by using this study which considered regional characters and the correlation among ${{\sigma}_v}'-Dr-N$.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.274-281
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• 2016

Background: Whole-body counters are widely used to evaluate internal contamination of the internal presence of gamma-emitting radionuclides. In internal dosimetry, it is a basic requirement that quality control procedures be applied to verify the reliability of the measured results. The implementation of intercomparison programs plays an important role in quality control, and the accuracy of the calibration and the reliability of the results should be verified through intercomparison. In this study, we evaluated the reliability of 2 whole-body counting systems using 2 calibration methods. Materials and Methods: In this study, 2 whole-body counters were calibrated using a reference male bottle manikin absorption (BOMAB) phantom and a Radiation Management Corporation (RMC-II) phantom. The reliability of the whole-body counting systems was evaluated by performing an intercomparison with International Atomic Energy Agencyto assess counting efficiency according to the type of the phantom. Results and Discussion: In the analysis of counting efficiency using the BOMAB phantom, the performance criteria of the counters were satisfied. The relative bias of activity for all radionuclides was -0.16 to 0.01 in the Fastscan and -0.01 to 0.03 in the Accuscan. However, when counting efficiency was analyzed using the RMC- II phantom, the relative bias of $^{241}Am$ activity was -0.49 in the Fastscan and 0.55 in the Accuscan, indicating that its performance criteria was not satisfactory. Conclusion: The intercomparison process demonstrated the reliability of whole-body counting systems calibrated with a BOMAB phantom. However, when the RMC-II phantom was used, the accuracy of measurements decreased for low-energy nuclides. Therefore, it appears that the RMC-II phantom should only be used for efficiency calibration for high-energy nuclides. Moreover, a novel phantom capable of matching the efficiency of the BOMAB phantom in low-energy nuclides should be developed.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2394-2398
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• 2013

Nicotine is the main component of environmental tobacco smoke, and its presence in indoor air is widely used as a secondhand-smoke indicator. Environmental tobacco smoke is a major source of indoor air pollution, but sufficient investigation of the uncertainty of its measurement, which mirrors the reliability of nicotine measurement, has not been performed. We calculated the uncertainty of measurement of indoor air nicotine concentration at low, medium, and high concentrations of 11.3798, 10.1977, $98.3768{\mu}g/m^3$, respectively, and we employed the Guide to the Expression of Uncertainty in Measurements (GUM), proposed by the International Organization for Standardization (ISO). The factors considered in determining the uncertainty were uncertainty of the calibration curve (calibration curve and repeated measurements), desorption efficiency, extraction volume, and sampling airflow (accuracy and acceptable limits of flowmeter). The measurement uncertainty was highest at low concentrations; the expanded measurement uncertainty is $0.9435{\mu}g/m^3$ and is represented as a relative uncertainty of 63.38%. At medium and high (concentrations, the relative uncertainty was 13.1% and 9.1%, respectively. The uncertainty of the calibration curve was largest for low indoor nicotine concentrations. To increase reliability of measurement in assessing the effect of secondhand smoke, measures such as increasing the sample injection rate ($1{\mu}L$ or more), increasing sampling volume to increase collected nicotine, and using gas chromatography-mass spectrometry (GC/MS) or GC/MS/MS, which has a lower quantitation threshold, rather than gas chromatography with nitrogen phosphorous detector, should be considered.

• Geomechanics and Engineering
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• 제37권5호
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• pp.431-441
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• 2024

A newly developed line-style sand pluviator has been calibrated to prepare repeatable sand specimens of specific statuses of compactness and homogeneity for laboratory tests. Sand is falling via a bottom slot of a fixed hopper, and by moving the sample container under the slot, the container is evenly filled with sand. The pluviator is designed with high flexibility: The falling height of sand, the hopper's opening width and the relative moving speed between the hopper and the sample box can be easily adjusted. By changing these control factors, sand specimens of a wide range of densities can be prepared. A series of specimen preparation was performed using the coarse Merwede River sand. Performance of the pluviator was systematically evaluated by exploring the alteration of achievable density, as well as checking the homogeneity and fabric of the prepared samples by CT scanning. It was found that the density of prepared coarse sand samples has monotonic correlations with none of the three control factors. Furthermore, CT scanning results suggested that the prepared samples exhibited excellent homogeneity in the horizontal direction but periodical alteration of density in the vertical direction. Based on these calibration test results, a preliminary hypothesis is proposed to describe the general working principles of this type of pluviators a priori, illustrating the mechanisms dominating the non-monotonic correlations between control factors and the relative density as well as the vertically prevalent heterogeneity of specimens. Accordingly, practical recommendations are made in a unified framework in order to lessen the load of similar calibration work.

• Progress in Superconductivity
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• 제14권1호
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• pp.45-51
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• 2012

마이크로파 측정법으로 ~40 GHz의 공진주파수를 지닌 공진기를 이용하여 비파괴적으로 YBCO 초전도체 박막의 두께를 측정할 경우 calibration용 YBCO 박막의 두께의 불확도가 마이크로파로 측정된 두께의 불확도에 미치는 영향을 70 - 360 nm 두께를 지닌 5 개의 YBCO 박막에 대해 연구하였다. Calibration용 박막으로는 약 150 nm의 두께를 지닌 박막이 사용되었는데, 이 박막의 두께의 불확도는 박막 표면의 거칠기를 고려하여 결정하였다. 본 연구 결과, calibration용 박막의 불확도가 마이크로파로 측정된 박막의 두께에 상당한 영향을 준다는 것을 확인하였으며, ~ 40 GHz에서 연구에 사용된 모든 박막에 대해 측정 두께가 5% 이내의 상대 불확도를 지니기 위해서는 calibration용 박막의 두께의 상대 표준불확도가 2.7% 이내의 값을 가져야 함을 알 수 있었다. 본 연구 결과는 마이크로파를 이용하여 박막의 두께를 측정할 경우 측정 두께의 상대 불확도의 목표치를 구현하기 위해서는 표면 거칠기로 인한 두께의 불확도가 일정 값 이하인 박막 만이 calibration용 박막으로 사용될 수 있음을 보여준다.

• Journal of Radiation Protection and Research
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• 제42권2호
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• pp.83-90
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• 2017

Background: Different cases exist in the measurement of thyroid radiobioassays owing to the individual characteristics of the subjects, especially the potential variation in the counting efficiency. An In situ Object Counting System (ISOCS) was developed to perform an efficiency calibration based on the Monte Carlo calculation, as an alternative to conventional calibration methods. The purpose of this study is to evaluate the applicability of ISOCS to thyroid radiobioassays by comparison with a conventional thyroid monitoring system. Materials and Methods: The efficiency calibration of a portable high-purity germanium (HPGe) detector was performed using ISOCS software. In contrast, the conventional efficiency calibration, which needed a radioactive material, was applied to a scintillator-based thyroid monitor. Four radioiodine samples that contained $^{125}I$ and $^{131}I$ in both aqueous solution and gel forms were measured to evaluate radioactivity in the thyroid. ANSI/HPS N13.30 performance criteria, which included the relative bias, relative precision, and root-mean-squared error, were applied to evaluate the performance of the measurement system. Results and Discussion: The portable HPGe detector could measure both radioiodines with ISOCS but the thyroid monitor could not measure $^{125}I$ because of the limited energy resolution of the NaI(Tl) scintillator. The $^{131}I$ results from both detectors agreed to within 5% with the certified results. Moreover, the $^{125}I$ results from the portable HPGe detector agreed to within 10% with the certified results. All measurement results complied with the ANSI/HPS N13.30 performance criteria. Conclusion: The results of the intercomparison program indicated the feasibility of applying ISOCS software to direct thyroid radiobioassays. The portable HPGe detector with ISOCS software can provide the convenience of efficiency calibration and higher energy resolution for identifying photopeaks, compared with a conventional thyroid monitor with a NaI(Tl) scintillator. The application of ISOCS software in a radiation emergency can improve the response in terms of internal contamination monitoring.

• 한국물환경학회지
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• 제37권6호
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• pp.510-519
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• 2021

Volatile Organic Compounds (VOCs) in sediments, which can cause human health problems, have been monitored in Korea since 2014. Measured VOC concentrations can be affected by matrix type and the volatility of target substances. In this study, (1) VOCs volatility and the influence of matrix interference were confirmed, and (2) internal standards (IS) method was applied to improve analytical method. For these purposes, method detection limit (MDL), calibration linearity, precision and accuracy of VOCs were compared in various matrices using the IS. Some of VOCs in sediments showed different peak areas and reduced rates compared to water matrix. It was suggested that adsorption properties of sediments hindered the migration to vapor during heat pretreatment in headspace method. A calibration curve was created in clean sand. Recovery rates for the calibration curve method and IS applying method were 64.1~83.1% and 99.1~119.3%, respectively. Relative standard deviations ranged from 11.1% to 21.6% for the calibration curve method and those for IS ranged 4.7% to 13.7%. In case of real sediment, calibration curve and 1,2-Dichlorobenzene-d4 (ODCB) among IS were not suitable. The average recovery rate of Fluorobenzene (FBZ) increased by 56.4% and Relative Standard Deviation (RSD) by 4.7%. However, the recovery rate was increased in the samples with large values of igniting intensity. This study confirmed that influence of the matrix of VOCs in sediment, and addition of IS materials improved precision and accuracy. Although IS corrects volatilization and adsorption, it is recommended that more than two types of IS should be added rather than single.