Study on the CZT Detector Calibration Method Through HPGe Detector Calibration Method

Young-Il Na,Min-Chul Kim,Gi-Lim Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The dismantling nuclear power plant is expected to continue to change the radiation working environment compared to the operating nuclear power plant. Contamination monitors and survey meters currently in use have limitations in accurate analysis source term and dose rates for continuous changes in radiation fields at dismantling sites. Due to these limitations, the use of semiconductor detectors such as HPGe and CZT detectors with excellent energy resolution and portability is increasing. The CZT detector performs as well as the HPGe detector, but there is no proven calibration procedure yet. Therefore, in this study, the HPGe calibration method was reviewed to derive implications for the CZT detector calibration method. The operating principle of a semiconductor detector that measures gamma emission energy converts them into electrical signals is the same. Two calibrations of HPGe detectors are performed according to the standard calibration procedure for semiconductor detectors for gamma-ray measurement issued by the Korea Association of Standards & Testing Organizations. The first is an energy calibration that calculates gamma-ray peak position measurements and relational expressions using standard source term that emit gamma-rays. The channel values for energy are measured using certified reference source term to determine radionuclides by identifying channels corresponding to the measured peak energy values. The second is the measurement efficiency of measuring the coefficient calibration device, which measures gamma rays emitted from the standard source term. The detector efficiency by sample or distance is measured in consideration of the shape, size, volume, and density of the calibration device. The HPGe detector performs calibration once every six months through a verified calibration method and is being used as a source term analyzer at the power plant. The CZT detector may also establish a procedure for identifying peak positions through energy calibration and calculating radioactivity through efficiency calibration. This will be a way to expand the usability of semiconductor detectors and further monitor radiation in a more effective way.

Detection of Calibration Patterns for Camera Calibration with Irregular Lighting and Complicated Backgrounds

Dong-Joong Kang,Jong-Eun Ha,Mun-Ho Jeong 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.5

This paper proposes a method to detect calibration patterns for accurate camera calibration under complicated backgrounds and uneven lighting conditions of industrial fields. Required to measure object dimensions, the preprocessing of camera calibration must be able to extract calibration points from a calibration pattern. However, industrial fields for visual inspection rarely provide the proper lighting conditions for camera calibration of a measurement system. In this paper, a probabilistic criterion is proposed to detect a local set of calibration points, which would guide the extraction of other calibration points in a cluttered background under irregular lighting conditions. If only a local part of the calibration pattern can be seen, input data can be extracted for camera calibration. In an experiment using real images, we verified that the method can be applied to camera calibration for poor quality images obtained under uneven illumination and cluttered background.

인터벤션에서 Calibration mode에 대한 오차율 비교

공창기(Chang gi Kong),류영환(Young hwan Ryu) 한국방사선학회 2020 한국방사선학회 논문지 Vol.14 No.5

이 연구의 목적은 경피적 혈관내 풍선 확장술이나 스텐트 삽입술에서 Balloon이나 Stent의 직경 및 길이를 예측 할 때 사용되는 정량적인 평가 도구인 Calibration Mode중 Catheter Calibration Mode, Auto Calibration Mode 그리고 Segment Calibration Mode에서의 오차율에 대해 알아보고자 하였다. Calibration의 정량적인 평가를 위해 정교하게 제작된 직경 × 길이(2 mm × 80 mm) Copper Wire와 5, 10, 15, 30, 40 mm의 Metal Ball을 이용하여 실험하였고, 아크릴 팬텀은 25 mm, 50 mm, 75mm, 100 mm, 125 mm, 150mm, 175 mm, 200 mm로 하여 각각의 높이에서 혈관조영 촬영장치로 Subtraction 영상을 획득하여 장비 회사에서 제공하는 소프트웨어인 Stenosis Analysis Tools을 이용하여 측정하였다. Catheter Calibration Mode에서의 오차율을 평가하기 위한 방법으로 Copper Wire를 각각의 아크릴 팬텀위에 올려놓고 촬영하였으며, Copper Wire 직경 2 mm를 Catheter의 직경으로 Setting하였고, 길이 8 mm Copper Wire의 길이를 Multi-segments로 측정하여 분석한 결과 1.13 ~ 5.63%의 오차율이 나타났다. Auto Calibration Mode에서의 오차율을 평가하기 위한 방법으로 각각의 아크릴 팬텀을 높이에서 아크릴 높이에 대한 수치를 입력하고, 8 mm Copper Wire의 길이를 Multi-segments 측정하여 분석한 결과 0 ~ 0.26%의 오차율이 나타났다. Segment Calibration Mode에서의 오차율을 평가하기 위한 방법으로 테이블 바닥에 있는 각각의 Metal Ball을 각각 Calibration하고, 각각의 아크릴 팬텀 위에 올려 있는 8 mm Copper Wire의 길이를 측정하여 아크릴 팬텀 높이 변화에 대한 8 mm Copper Wire 길이를 Mutli-segments 측정하여 분석한 결과 1.05 ~ 19.04%의 오차율이 나타났다. 그리고 Auto Calibration Mode에서 OID 변화에 대한 실험은 아크릴 팬텀의 높이는 100mm로 고정하고 OID만 450 mm ~ 600 mm로 변화를 하였을때 오차율은 0.13 ~ 0.38%로 나타났다. 결론적으로 소프트웨어에서 제공하는 정량적인 혈관의 치수평가를 하기 위한 이들 Calibration Mode 중 Auto Calibration Mode에서 높이 값을 입력하는 것이 오차율이 가장 적은 Calibration 방법임을 확인하였으며, Metal ball이나 기타 다른 물체를 이용하여 Calibration을 하기 위해서는 시술부위와 동등한 높이에 놓고 Calibration을 하는 방법이 오차율을 가장 줄일 수 있는 방법으로 사료된다. This study aimed to identify the error rates in Catheter Calibration Mode, Auto Calibration Mode, and Segment Calibration Mode among many calibration modes as a quantitative evaluation tool used for predicting the diameter and length of balloon or stent in percutaneous intravascular balloon dilatation or stent insertion. Our experiment was conducted with Copper Wire of 2 mm × 80 mm (diameter × length) manufactured elaborately for quantitative evaluation in calibration and Metal Ball of 5, 10, 15, 30, and 40 mm and Acryl Phantom of 25 mm, 50 mm, 75mm, 100 mm, 125 mm, 150mm, 175 mm, and 200 mm. At each height, subtraction images were acquired with a cineangiograph and Stenosis Analysis Tool as a software provided by the equipment company was used for measurement. To evaluate the error rates in Catheter Calibration Mode, Copper Wire was put on each acryl phantom before shooting. Copper Wire of 2 mm in diameter was set as a diameter for catheter, and Copper Wire of 8 mm in length was measured with Multi-segments. As a result, the error rates appeared at 1.13 ~ 5.63%. To evaluate the error rates in Auto Calibration Mode, the height of acryl was entered at each height of acryl phantom and the length of 8 mm Copper Wire was measured with Multi-segments and as a result, the error rates appeared at 0 ~ 0.26%. To evaluate the error rates in Segment Calibration Mode, each metal ball on the floor of table was calibrated and the length of 8 mm Copper Wire on each acryl phantom was measured and the length of 8 mm Copper Wire depending on the changes of acryl phantom height was measured with Mutli-segments and as a result, the error rates appeared at 1.05 ~ 19.04%. And in the experiment on OID changes in Auto Calibration Mode, the height of acryl phantom was fixed at 100mm and OID only changed within the range of 450 mm ~ 600 mm and as a result, the error rates appeared at 0.13 ~ 0.38%. In conclusion, it was found that entering the height values in Auto Calibration Mode, among these Calibration Modes for evaluating quantitative vascular dimensions provided by the software was the calibration method with the least error rates and it is thus considered that for calibration using a metal ball or other objects, putting them in the same height as that of treatment sites before calibrating is the method that can reduce the error rates the most.

적외채널 기본 복사보정 결과를 이용한 기하보정 처리의 정확도 분석

서석배(Seok-Bae SEO),권은주(Eun-Joo KWON),진경욱(Kyoung-Wook JIN) 한국항공우주연구원 2013 항공우주기술 Vol.12 No.2

천리안위성 기상탑재체 적외채널의 복사보정에서는 기본 복사보정식을 기반으로 다섯 개의 알고리즘이 추가되어 있다. 일반적으로 기하보정은 복사보정 이후 수행하므로, 복사보정 완료시각은 기하보정 처리의 시작시각을 결정한다. 본 논문에서는 기하보정 처리의 시작시각을 앞당기는 방법을 제안하기 위해서, 기본 복사보정 및 정밀 복사보정(기본 복사보정에 다섯 개의 알고리즘 추가) 결과를 입력으로 수행한 기하보정 처리의 정확도를 비교 분석한 내용을 정리하였다. 처리속도가 빠른 기본 복사보정의 결과와 정확한 복사보정 값을 포함하는 정밀복사보정의 결과를 입력으로 각각의 기하보정 처리의 정확도를 분석하는 실험을 수행하였고, 두 경우 모두 기하보정 정확도 요구사항을 만족시킴을 검증하였다. 따라서 기하보정 처리 속도를 향상시키기 위해서, 기본 복사보정식으로 생성된 결과를 기하보정 처리의 입력으로 사용할 수 있음을 확인하였다. The nominal radiometric calibration equation and additional five algorithms are applied in the infrared channel radiometric calibration for the COMS (Communication, Ocean, Meteorological Satellite) MI (Meteorological Imager). The processing end time of the radiometric calibration is directly related with the start time of geometric calibration processing since the geometric calibration processing is followed by that of the radiometric calibration. This paper describes comparison and analysis results for geometric calibration processing using two types of the radiometric calibration results, outputs from only the nominal radiometric calibration equation and outputs from the complete one (the nominal radiometric calibration equation with additional five algorithms), to propose a method with the earlier start time of the geometric calibration processing. Experimental results show that both of radiometric calibration results, from the nominal radiometric calibration equation with a fast processing speed and from the complete one with accurate radiometric values, can be used in the geometric calibration as the appropriate inputs because those processing results satisfied the requirements of geometric calibration processing accuracy. Thus the radiometric calibration results from the nominal radiometric calibration equation can be used to improve geometric calibration processing time.

LCD 디스플레이의 하드웨어 캘리브레이션과 소프트웨어 캘리브레이션 품질 비교 연구

김현서,이용환 현대사진영상학회 2014 현대사진영상학회논문집 Vol.17 No.3

This research aims to study the correctional integrity of LCD digital photo reproductionby analyzing the differences of reproduction quality depending on LCD monitor calibrationmethod. Using monitors that support hardware calibration and calibrating each monitorusing hardware and software calibration, this research aims to provide a standard forevaluating the characteristics of each correction method by measuring and analyzing thedifferences of color image quality between each correction method result. To ensure objectivity of the research, four monitors from five different manufacturersthat support hardware calibration were used. The research took into account the differencein calibration that could be caused by the BLU (backlight unit) type’s specific propertiesfor various BLU types reflected differences into the measurement results of the research. Colorimeter and spectrophotometer sensors were used to measure displays, and in order tominimize measurement discrepancies that could be caused by specific sensor properties,various manufacturers of these sensors were used. In order to measure and evaluate the image quality for each calibration method, WhitePoint and Tone Reproduction were the analysis factors that were compared, and in orderto increase the objectivity of the results, all monitors were normalized to the sameLuminance level. By measuring and analyzing the resulting image quality, this research aimsto evaluate the accuracy and usefulness for each calibration method. The results of the test showed that for some calibration conditions, it was confirmedthat HW calibration did not show a clear difference compared to SW calibration. In thecase of White Point and Luminance, HW calibration did not show more correctional effectsthan SW calibration. For the Tone Reproduction characteristic, when the data was analyzedbased on Gamma, it was confirmed that there was a statistical significance in thedifference of the results that HW calibration, albeit slightly, showed a better correctionaleffect than SW calibration. In the case for Blackpoint, the statistical significance was also confirmed that HWcalibration gave a better Blackpoint quality. Therefore, HW calibration shows bettercorrectional effects for both Blackpoint and Tone Reproduction. For fine art pictures thatneed detailed grayscale, more quality benefit was provided by HW calibration compared toSW calibration. However, for 2D Vector-based design areas such as Illustrator designs andtypography, there was little to no benefit to be gained through HW calibration, and in thiscase, for color, it can be concluded that through just SW calibration it is possible toachieve image and color quality with no statistical difference with that of HW calibration.

Infrared Camera Calibration in the 3D Temperature Field Reconstruction

Sun Xiaoming,Wu Haibin,Wang Wei,Liubo,Cui Guoguang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.6

In order to reconstruct the 3D temperature field based on the binocular vision system, we carry out a research on the calibration of the infrared camera. To start with, we make a calibration board which can be clearly identified by the infrared camera; then, with the help of OpenCV, we implement the calibration of two infrared cameras respectively and rectify the infrared images. According to the parameters obtained from the single infrared camera calibration, we accomplish the stereo calibration. The experimental results show that the average reprojecting error is below 0.14 pixels and when using the system to carry out a real measurement, the average error is 3.12%. The feasibility of the proposed calibration approach is verified, the experimental measurement results is close to the ground truth.

Evaluation of Robot Calibration Performance based on a Three Dimensional Small Displacement Measuring Sensor

Hoai-Nhan Nguyen,Hee-Jun Kang(강희준) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.12

There have been many autonomous robot calibration methods which form closed loop structures through the various attached sensors and mechanical fixtures. Single point calibration among them has been used for on-site calibration due to its convenience of implementation. The robot can reach a single point with infinitely many configurations so that single point calibration algorithm can be set up and easily implemented relative to the other methods. However, it is not still easy to drive the robots’ sharp edge to its corresponding edge of the fixture. This is error-prone process. In this paper, we propose a 3 dimensional small displacement measuring sensor and a robot calibration algorithm based on this sensor. This method relieves the difficulty of matching two edges in the single point calibration and improves the resulting robot accuracy. Simulated study is carried out on a Hyundai HA06 robot to show the effectiveness of the proposed method over the single point calibration. And also, the resulting robot accuracy is compared with that from 3D laser tracker based calibration to show the dependency of robot accuracy on range of the workspace where the measurement data are collected.

대형 평판 디스플레이의 정밀 정렬을 위한 캘리브레이션 기술

홍준호(Jun-Ho Hong),신동원(Dongwon Shin) 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.3

In this study, calibration technology that increases the alignment accuracy in large flexible flat panels was studied. For precise of calibration, a systematization of the calibration algorithm was established, and a calibration correction technique was studied to revise calibration errors. A coordinate systems of camera and UVW stage was established to get the global position of the mark, and equations for translational and rotational calibration were systematically derived based on geometrical analysis. Correction process for the calibration data was carried, and alignment experiments were performed sequentially in cases of the presence or absence of calibration-correction. Alignment results of both calibration correction and non-calibration correction showed accuracy performance less than 1μm. On the other hand, the standard deviation in calibration-correction is smaller than non-calibration correction. Therefore, calibration correction showed improvement of the alignment repeatability.

Research on Camera Calibration in Football Broadcast Videos

Shouzhong Zhang 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.3

A novel continuous camera calibration algorithm is proposed, which can address the calibration for non-goal area of soccer video. By considering the fact that the position of main camera is stable, a novel continuous camera calibration algorithm is proposed for soccer video analysis. There are two stages for calibration: the first stage addresses the calibration only for goal area and the position of camera is computed and recorded, and then the second stage can address calibration for any area including non-goal area where the camera position is given at first stage. Thus, the proposed algorithm can address the calibration for non-goal area of soccer video, which cannot be addressed by traditional calibration algorithms since the inadequate of calibration objects.

판독용 LCD 컬러 모니터 장치의 성능 평가 - 성능 평가 및 Calibration 주기 결정을 중심으로 : 판독용 LCD 컬러 모니터 장치의 성능 평가

이원홍(Won-Hong Lee),손순룡(Soon-Yong Son),노성순(Sung-Soon Noh),이인화(In-Hwa Lee),강성호(Sung-Ho Kang),이용문(Yong-Moon Lee),박재수(Jae-Soo Park),윤석환(Seok-Hwan Yoon) 대한방사선과학회(구 대한방사선기술학회) 2008 방사선기술과학 Vol.31 No.1

목 적: 판독용 모니터의 성능을 평가하는데 있어 불필요한 시간 및 인력 등을 줄이고 판독의 최적화 유지와 모니터의 upgrade 시기, 그리고 교체 시기를 결정할 수 있는 시스템을 구축하는데 필요한 적절한 수준의, 일정기간의 성능평가 관리 주기 및 calibration 주기를 결정하고자 하였다. 대상 및 방법: 판독용 LCD 컬러 모니터(CCL350i, Totoku, Japan) 20대를 대상으로 2007년 3월부터 8월(첫 calibration 후 3, 4, 5, 6, 7, 8개월째)까지 매달 1회에 걸쳐 한 달 주기로 총 6회의 성능 평가를 하였다. 성능평가에 사용된 측정 도구는 휘도계(DTP 94 39630, X-Rite Inc. U.S.A.)와 조도계(LX-101 Q031871, Lutron, U.S.A.) 그리고 모니터 성능관리 프로그램인 AAPM TG 18 protocol를 이용하였다. 성능평가 항목은 기하학적 왜곡(geometric distortion), 반사 테스트(reflection test), 휘도 반응 평가(luminance response evaluation), 휘도 균일도(luminance uniformity), 분해능(resolution), 노이즈(noise), 베이링 그레어(veiling glare), 색도(chromaticity) 등 8개 항목을 포함하였다. 결 과: 기하학적 왜곡 평가와 반사 테스트, 휘도 균일도 테스트, 분해능, 노이즈 평가, 베이링 그레어 테스트, 색도 테스트 등은 AAPM TG 18에서 권고하는 기준치에 모두 부합되었다. 휘도반응평가 중 예측되는 최대 휘도와 관측되는 휘도의 편차 항목에서 4개월째부터 25%(4대)의 모니터가 8개월째까지 기준 편차를 벗어나기 시작하였으며, 8개월째에는 다른 모니터 7대에서도 편차를 보이기 시작하여 전체적으로 55%(11대)의 모니터에서 기준 편차를 벗어나고 있었다. 또한 대조도 반응의 편차 항목에서 4개월째부터 예측되는 최대 휘도와 관측되는 휘도의 편차의 기준치를 벗어나기 시작한 4대의 모니터 중 5%(1대)에서 4개월째부터 8개월째까지, 또 다른 2대는 8개월째부터 편차를 보여 전체적으로 8개월째에는 15%(3대)의 모니터에서 기준 편차를 벗어났다. 결 론: 성능평가의 주기는 calibration 후 4개월째부터 오차 범위를 벗어나는 결과와 모니터 수 그리고 성능검사에 소요되는 인력 및 시간을 고려할 때 3개월에 한번씩 평가함이 효율적이라고 판단된다. 또한 calibration 주기는 8개월째부터 50% 이상에서 편차를 보인 결과 및 성능평가 주기를 고려할 때 calibration 후 6개월을 주기로 calibration을 다시 시행하여야 할 것으로 판단된다. Purpose: This study is to decide a quality control and calibration period of LCD display devices used for reading diagnostic images. Materias and Methods: The assessment test of 20 flat panel LCD color display devices used for reading diagnostic images were performed based on AAPM TG 18 protocol over the total six sessions at one month intervals from three months after primary calibration, in terms of geometric distortion, reflection test, luminance response evaluation, luminance uniformity, resolution, noise, veiling glare and chromaticity test. Results: The results of geometric distortion, reflection test, luminance uniformity, resolution, noise, veiling glare and chromaticity test were within the criteria recommended by AAPM TG 18, except for luminance response evaluation. In the measured luminance deviation of luminance response evaluation, 4(25%) of 20 display devices were passed a criterion from four months after calibration, and 11(55%) were passed from eight months. Also in the contrast response of the luminance response evaluation, 1(5%) display device was passed a criterion from four months after calibration, and 3(15%) were passed from eight months. Conclusion: Considering the passing deviation after calibration, the time required and a manpower, the quality control and calibration period of LCD display devices used for reading diagnostic images should be a three months and six months after calibration.