• Title/Summary/Keyword: Comparative calibration

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A Study on Calibration Procedures for Ir-192 High Dose Rate Brachytherapy Sources (고선량률(HDR) 근접치료의 동위원소 Ir-192에 대한 측정방법에 관한 고찰)

  • Baek, Tae-Seong;Lee, Seung-Wook;Na, Soo-Kyong
    • The Journal of Korean Society for Radiation Therapy
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    • v.19 no.1
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    • pp.19-26
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    • 2007
  • Purpose: To compare of the accuracy among various measurement procedures of HDR Brachytherapy, and to evaluate the clinical suitability and usefulness of alternative PMMA (polymethylmethacrylateplastics: $C_5H_8O_2$) plate phantom without any additional cost due to the purchase of measuring apparatus. Materials and Methods: We made a comparative study on three types of measuring systems: well type chamber, source calibration jig, and PMMA plate phantom. Farmer type chamber was used for source calibration jig method and PMMA plate phantom method. Measurement was done 5 times each in comparison with the measurement values from manufacturer. Measurement results from experiment were compared with that from the manufacturer which is offered with the source whenever a source is substituted by a new one and evaluate the accuracy of source activity. Results: As a consequence of Ir-192 source measurement using well type chamber, source calibration jig and PMMA plate phantom, RMS (Root Mean Square) values for the relative error are 0.6%, 1.57%, 2.1%, respectively, compared with the data from manufacturer. And the mean errors with standard deviation are given $-0.2{\pm}0.5%$, $0.97{\pm}1.23%$, $-0.89{\pm}1.87%$ respectively. Conclusion: From the results shown by the three types of measurement system (well type chamber, source calibration jig, and PMMA plate phantom), the measurement with well type chamber produced the best accuracy. It turns out that we can also use the alternative system of PMMA plate phantom clinically without purchasing any additional particular apparatus since the system does not exceed the recommendation of AAPM (American Association of Physicists in Medicine), which requires the error range of within ${\pm}5%$.

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A Novel Calibration Method Research of the Scale Factor for the All-optical Atomic Spin Inertial Measurement Device

  • Zou, Sheng;Zhang, Hong;Chen, Xi-yuan;Chen, Yao;Fang, Jian-cheng
    • Journal of the Optical Society of Korea
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    • v.19 no.4
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    • pp.415-420
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    • 2015
  • A novel method to measure the scale factor for the all-optical atomic spin inertial measurement device (ASIMD) is demonstrated in this paper. The method can realize the calibration of the scale factor by a self-consistent method with small errors in the quiescent state. At first, the matured IMU (inertial measurement unit) device was fixed on an optical platform together with the ASIMD, and it has been used to calibrate the scale factor for the ASIMD. The results show that there were some errors causing the inaccuracy of the experiment. By the comparative analysis of theory and experiment, the ASIMD was unable to keep pace with the IMU. Considering the characteristics of the ASIMD, the mismatch between the driven frequency of the optical platform and the bandwidth of the ASIMD was the major reason. An all-optical atomic spin magnetometer was set up at first. The sensitivity of the magnetometer is ultra-high, and it can be used to detect the magnetization of spin-polarized noble gas. The gyromagnetic ratio of the noble gas is a physical constant, and it has already been measured accurately. So a novel calibration method for scale factor based on the gyromagnetic ratio has been presented. The relevant theoretical analysis and experiments have been implemented. The results showed that the scale factor of the device was $7.272V/^{\circ}/s$ by multi-group experiments with the maximum error value 0.49%.

A comparative Analysis of Overseas Cases to Enhance Effectiveness of CEO's Safety and Health Duties - Focusing on Serious Accidents Punishment Act(SAPA) and Singapore's New System - (경영책임자 안전보건의무 실효성 제고를 위한 해외사례 비교분석 - 중대재해처벌법과 싱가포르 신설 제도를 중심으로 -)

  • Jeongung Lee;Jaewook Jeong
    • Journal of the Korean Society of Safety
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    • v.38 no.1
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    • pp.55-61
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    • 2023
  • Although corporate punishment-related systems are being implemented in several countries, such as South Korea's Serious Accidents Punishment Act (SAPA), related research has mainly focused on legal issues. This study aimed to compare and analyze the SAPA and Singapore's Workplace Safety and Health Act (WSHA) and Code of Practice on Chief Executives' and Board of Directors' Workplace Safety and Health Duties (WSHD). In addition, it was attempted to draw implications to enhance the effectiveness of the CEO's safety and health duties. For this study, a comparative analysis was conducted in 3 steps. In step 1, similar overseas systems were investigated. In step 2, the system contents were classified into four viewpoints (DUTY, RESOURCE, Other factors, and Main contents), and comparison items were derived from each viewpoint. In step 3, the viewpoints were compared, and implications were derived. The following three implications were derived through comparative analyses. 1) In WSHD, additional explanation and calibration of measures clarify the CEO's role, and 2) It is easy to use for the CEO's duties by providing the resources directly. 3) Penalties for violating the proposed duties are entrusted to the existing higher-level laws. Considering this, providing detailed content and related information for the CEO would possibly improve the SAPA to fulfill his/her duties through announcements from related organizations in the future.

ADVANTAGES OF USING ARTIFICIAL NEURAL NETWORKS CALIBRATION TECHNIQUES TO NEAR-INFRARED AGRICULTURAL DATA

  • Buchmann, Nils-Bo;Ian A.Cowe
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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    • 2001.06a
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    • pp.1032-1032
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    • 2001
  • Artificial Neural Network (ANN) calibration techniques have been used commercially for agricultural applications since the mid-nineties. Global models, based on transmission data from 850 to 1050 nm, are used routinely to measure protein and moisture in wheat and barley and also moisture in triticale, rye, and oats. These models are currently used commercially in approx. 15 countries throughout the world. Results concerning earlier European ANN models are being published elsewhere. Some of the findings from that study will be discussed here. ANN models have also been developed for coarsely ground samples of compound feed and feed ingredients, again measured in transmission mode from 850 to 1050 nm. The performance of models for pig- and poultry feed will be discussed briefly. These models were developed from a very large data set (more than 20,000 records), and cover a very broad range of finished products. The prediction curves are linear over the entire range for protein, fat moisture, fibre, and starch (measured only on poultry feed), and accuracy is in line with the performance of smaller models based on Partial Least Squares (PLS). A simple bias adjustment is sufficient for calibration transfer across instruments. Recently, we have investigated the possible use of ANN for a different type of NIR spectrometer, based on reflectance data from 1100 to 2500 nm. In one study, based on data for protein, fat, and moisture measured on unground compound feed samples, dedicated ANN models for specific product classes (cattle feed, pig feed, broiler feed, and layers feed) gave moderately better Standard Errors of Prediction (SEP) compared to modified PLS (MPLS). However, if the four product classes were combined into one general calibration model, the performance of the ANN model deteriorated only slightly compared to the class-specific models, while the SEP values for the MPLS predictions doubled. Brix value in molasses is a measure of sugar content. Even with a huge dataset, PLS models were not sufficiently accurate for commercial use. In contrast an ANN model based on the same data improved the accuracy considerably and straightened out non-linearity in the prediction plot. The work of Mr. David Funk (GIPSA, U. S. Department of Agriculture) who has studied the influence of various types of spectral distortions on ANN- and PLS models, thereby providing comparative information on the robustness of these models towards instrument differences, will be discussed. This study was based on data from different classes of North American wheat measured in transmission from 850 to 1050 nm. The distortions studied included the effect of absorbance offset pathlength variation, presence of stray light bandwidth, and wavelength stretch and offset (either individually or combined). It was shown that a global ANN model was much less sensitive to most perturbations than class-specific GIPSA PLS calibrations. It is concluded that ANN models based on large data sets offer substantial advantages over PLS models with respect to accuracy, range of materials that can be handled by a single calibration, stability, transferability, and sensitivity to perturbations.

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PD measuring on MV XLPE Calble by Using UWB Antenna (UWB 안테나를 이용한 MV급 전력케이블의 부분방전 측정 연구)

  • Yang, Sang-Hyun;Lim, Kwang-Jin;Lee, Yong-Sung;Park, Noh-Joon;Park, Dae-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.267-268
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    • 2008
  • This paper presents compact low frequency ultra-wide band(UWB) sensor design and studying of the partial discharge diagnosis by sensing electromagnetic pulse emitted from the partial discharge source with new designed UWB sensor. In this study, we designed new type of compact low frequency UWB sensor based on microstrip antenna technology to detect both low frequency and high frequency band of partial discharge signal. And experiments of offline PD testing on in medium voltage (22.9kV) underground cable and mention the comparative results with the traditional HFCT as a reference sensor in the laboratory. In the series of comparative test, the calibration signal injection test provided with conventional IEC 60270 method and high voltage injection testing are included.

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Measurement of CT Numbers for Effective Atomic Number And Physical Density of Compound (화합물의 물리적 밀도와 유효원자번호에 대한 CT수 측정)

  • Kim, Jong Eon
    • Journal of the Korean Society of Radiology
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    • v.15 no.2
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    • pp.125-130
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    • 2021
  • In the AAPM CT performance phantom, there is little data on the CT number of the effective atomic number and physical density corresponding to each peg and water of the CT number calibration insert. Therefore, the necessity of documentation was raised.The purpose of this study is to calculate the effective atomic number for each peg and water of the CT number calibration insert in the AAPM CT performance phantom, and to measure the CT number for the calculated effective atomic number and physical density for comparative analysis.In order to obtain CT number data on the effective atomic number and physical density of each peg and water from the CT number calibration insert of the AAPM CT performance phantom, the effective atomic number for each peg and water was first calculated. Then, CT slices were obtained by scanning the CT number calibration with a CT scanner. CT numbers were measured for each peg and water in the central CT slice. As a result, the CT numbers for the effective atomic number showed a nonlinear pattern of repeating the increase and decrease as the effective atomic number increased. In addition, the CT numbers for physical density showed a nonlinear pattern of repeating the increase and decrease as the physical density increased.

Comparative Measurement of Radioactivity with Standard Gamma-ray Ionization Chamber System (표준 감마선 전리함 장치에 의한 방사능 비교 측정)

  • Park, Tae-Soon;Woo, Dong-Ho;Oh, Pil-Jae;Hwang, Sun-Tae
    • Journal of Radiation Protection and Research
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    • v.9 no.1
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    • pp.11-18
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    • 1984
  • A Standard gamma-ray ionization chamber system was developed with a well type ionization chamber and micro current measuring circuit. Micro current was measured by the automatic Townsend balance with stepwise compensation method. For gamma emitting nuclides such as $^{241}Am,\;^{133}Ba,\;^{60}Co,\;^{134}Cs,\;^{137}Cs,\;and\;^{22}Na$ relative calibration factors to $^{226}Ra$ reference source were calculated and detection .efficiency curve was determined as a fudnction of gamma energy.

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A comparative study of numerical methods for fluid structure interaction analysis in long-span bridge design

  • Morgenthal, Guido;McRobie, Allan
    • Wind and Structures
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    • v.5 no.2_3_4
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    • pp.101-114
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    • 2002
  • Both a Finite Volume and a Discrete Vortex technique to solve the unsteady Navier-Stokes equations have been employed to study the air flow around long-span bridge decks. The implementation and calibration of both methods is described alongside a quasi-3D extension added to the DVM solver. Applications to the wind engineering of bridge decks include flow simulations at different angles of attack, calculation of aerodynamic derivatives and fluid-structure interaction analyses. These are being presented and their specific features described. If a numerical method shall be employed in a practical design environment, it is judged not only by its accuracy but also by factors like versatility, computational cost and ease of use. Conclusions are drawn from the analyses to address the question of whether computer simulations can be practical design tools for the wind engineering of bridge decks.

Propagation Characteristics of Acoustic Signals Produced by Partial Discharges in an Insulation Oil (유중 부분방전 음향신호의 전달특성)

  • Park, Dae-Won;Cha, Sang-Wook;Cho, Hyang-Eun;Kim, Dong-Geon;Kil, Gyung-Suk
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2011.06a
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    • pp.188-188
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    • 2011
  • This paper describes the propagation characteristics of acoustic signals as a function of distance from the location of partial discharge(PD) occurrence to analyze correlation between discharge magnitude and acoustic signal in insulation oil. We fabricated a decoupler and an amplifier to measure acoustic signals produced by PD. The amplifier has the gain of 40 dB and the frequency bandwidth of 1.6 kHz~1.6 MHz. After a comparative calibration by a standard pulse generator and a coupling capacitor, we analyzed the propagation characteristics of acoustic signals in insulation oil as a function of distance.

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Characteristic features of concrete behaviour: Implications for the development of an engineering finite-element tool

  • Kotsovos, Michael D.;Pavlovic, Milija N.;Cotsovos, Demetrios M.
    • Computers and Concrete
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    • v.5 no.3
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    • pp.243-260
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    • 2008
  • The present article summarises the fundamental characteristics of concrete behaviour which underlie the formulation of an engineering finite element model capable of realistically predicting the behaviour of (plain or reinforced) concrete structural forms in a wide range of problems ranging from static to impact loading without the need of any kind of re-calibration. The already published evidence supporting the proposed formulation is complemented by four additional typical case studies presented herein; for each case, a comparative study is carried out between numerical predictions and the experimental data which reveals good agreement. Such evidence validates the material characteristics upon which the FE model's formulation is based and provides an alternative explanation regarding the behaviour of structural concrete and how it should be modelled which contradicts the presently (widely) accepted assumptions adopted in the majority of FE models used to predict the behaviour of concrete.