• Title/Summary/Keyword: position detector

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Sensitivity of a control rod worth estimate to neutron detector position by time-dependent Monte Carlo simulations of the rod drop experiment

  • Jong Min Park;Cheol Ho Pyeon;Hyung Jin Shim
    • Nuclear Engineering and Technology
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    • v.56 no.3
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    • pp.916-921
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    • 2024
  • The control rod worth sensitivity to the neutron detector position in the rod drop experiment is studied by the time-dependent Monte Carlo (TDMC) neutron transport calculations for AGN-201K educational reactor and the Kyoto University Critical Assembly. The TDMC simulations of the rod drop experiments are conducted by the Seoul National University Monte Carlo (MC) code, McCARD, yielding time-dependent neutron densities at detector positions. The detector-position-dependent results of the total control rod worth calculated by the extrapolation, the integral counting, and the inverse methods are compared with the numerical reference using the MC eigenvalue calculations and the experimental results. From these comparisons, it is observed that the total control rod worth can be estimated with a considerable difference depending on the detector position through the rod drop experiment. The proposed TDMC simulation of the rod drop experiment can be applied for searching a better detector position or quantifying a bias for the control rod worth measurement.

Analysis on Activation Characteristic of Heat Detectors in a Compartment Fire (실내화재에서의 열감지기 동작특성 분석)

  • Ryu, Hocheol
    • Journal of the Society of Disaster Information
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    • v.10 no.4
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    • pp.598-608
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    • 2014
  • The first operation of alarm system starts at a detector. And the largest effect is produced on the operation of detector by the fire source position and installation position. Nevertheless, the Korean standard for the installation of detector only specifies matters of fire detector installation according to area and height, without consideration of installation position and fire source position. Therefore, this study carried out a fire test in consideration of detector installation position and fire source position (5 places) in order to minimize casualties owing to the fast operation of fire detector when a fire occurred. Considering that it took the longest time for a detector close to a wall to work in the results of this test, it was possible to find that a minimum clearance to the wall was required.

Positional correction of a 3D position-sensitive virtual Frisch-grid CZT detector for gamma spectroscopy and imaging based on a theoretical assumption

  • Younghak Kim ;Kichang Shin ;Aleksey Bolotnikov;Wonho Lee
    • Nuclear Engineering and Technology
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    • v.55 no.5
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    • pp.1718-1733
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    • 2023
  • The virtual Frisch-grid method for room-temperature radiation detectors has been widely used because of its simplicity and high performance. Recently, side electrodes were separately attached to each surface of the detectors instead of covering the entire detector surface with a single electrode. The side-electrode structure enables the measurement of the three-dimensional (3D) gamma-ray interaction in the detector. The positional information of the interaction can then be utilized to precisely calibrate the response of the detector for gamma-ray spectroscopy and imaging. In this study, we developed a 3D position-sensitive 5 × 5 × 12 mm3 cadmium-zinc-telluride (CZT) detector and applied a flattening method to correct detector responses. Collimated gamma-rays incident on the surface of the detector were scanned to evaluate the positional accuracy of the detection system. Positional distributions of the radiation interactions with the detector were imaged for quantitative and qualitative evaluation. The energy spectra of various radioisotopes were measured and improved by the detector response calibration according to the calculated positional information. The energy spectra ranged from 59.5 keV (emitted by 241Am) to 1332 keV (emitted by 60Co). The best energy resolution was 1.06% at 662 keV when the CZT detector was voxelized to 20 × 20 × 10.

Measurements of low dose rates of gamma-rays using position-sensitive plastic scintillation optical fiber detector

  • Song, Siwon;Kim, Jinhong;Park, Jae Hyung;Kim, Seunghyeon;Lim, Taeseob;Kim, Jin Ho;Kim, Sin;Lee, Bongsoo
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3398-3402
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    • 2022
  • We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and 137Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

A Study on the Position Compensation of a Mobile Robot Using 2D Position Sensitive Detector (2차원 PSD 를 이용한 이동로보트의 위치 보정에 관한 연구)

  • Ro, Young-Shick;Lee, Ki-Hyun
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.833-836
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    • 1995
  • The Position Sensitive Detector(PSD) is an useful which can be used to measurement the position of an incidence light in detail and in real-time. In this paper, light sources, to be predefinded positions, are used as landmarks and the 2-D PSD signals are used to compensate the position of a running mobile robot. To induce the position compensation algorithm, first, we inspect the error factor, make the error model, and evaluate the error covariance matrix between the real position and estimated position in dead reckoning system. Next we obtain an optimal position compensation algorithm to update the estimated position using extended Kalman filler by the relation of the external light position and it's PSD signal. Through the simulation of navigating a robot the effectiveness of the proposed method is confirmed.

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Position Measurements of Moving Object in Cartesian Coordinate (직교좌표에서 이동물체의 위치측정)

  • 이용중;노재희;이양범
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.1
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    • pp.36-42
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    • 2001
  • In this paper, PSD(Position Sensitive Detector) sensor system that estimates position for moving objects in 2D plane is developed. PSD sensor is used to measure the position the position of and incidence light in real-time. To get the position of light source of moving target, a new parameter calibration algorithm and neural network technique are proposed and applied. Real-time position measurements of the mobile robot with light source is examined to validate the proposed method. It is shown that the proposed technique provides accurate position estimation of the moving object.

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A Position Measurements of Moving Object in 2D Plane (2차원 평면상에서 이동하는 물체의 위치측정)

  • Ro, Jae-Hee;Lee, Yong-Jung;Choi, Jae-Ha;Ro, Young-Shick;Lee, Yang-Burm
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.12
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    • pp.1537-1543
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    • 1999
  • In this paper, PSD(Position Sensitive Detector) sensor system that estimates position for moving objects in 2D plane is developed. PSD sensor is used to measure the position of an incidence light in real-time. To get the position of light source of moving target, a new parameter calibration algorithm and neural network technique are proposed and applied. Real-time position measurements of the mobile robot with light source is examined to validate the proposed method. It is shown that the proposed technique provides accurate position estimation of the moving object.

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A study on the PSD sensor system for localization of mobile robots (이동 로봇의 위치측정을 위한 PSD 센서 시스템에 관한 연구)

  • Ro, Young-Shick
    • Journal of Institute of Control, Robotics and Systems
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    • v.2 no.4
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    • pp.330-336
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    • 1996
  • An real-time active beacon localization system for mobile robots is developed and implemented. This system permits the estimation of robot positions when detecting light sources by PSD(Position Sensitive Detector) sensor which are placed sparsely over the robots work space as beacons(or landmarks). An LSE(Least Square Estimation) method is introduced to calibrate the internal parameters of a model for the beacon and robot position. The proposed system has two operational modes of position estimation. One is the initial position calculation by the detection of two or more light sources positions of which are known. The other is the continuous position compensation that calculates the position and heading of the robot using the IEKF(Iterated Extended Kalman Filter) applied to the beacon and dead-reckoning data. Practical experiments show that the estimated position obtained by this system is precise enough to be useful for the navigation of robots.

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Navigation of a mobile robot using active landmarks (능동 표식을 이용한 이동 로봇의 운행)

  • 노영식;김재숙;권석근
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.916-919
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    • 1996
  • An real-time active beacon localization system for mobile robots is developed and implemented. This system permits the estimation of robot positions when detecting light sources by PSD(Position Sensitive Detector) sensor which are placed sparsely over the robot's work space as beacons(or landmarks). An LSE(Least Square Estimation) method is introduced to calibrate the internal parameters of a model for the beacon and robot position. The proposed system has two operational modes of position estimation. One is the initial position calculation by the detection of two or more light sources positions of which are known. The other is the continuous position compensation that calculates the position and heading of the robot using the IEKF(Iterated Extended Kalman Filter) applied to the beacon and dead-reckoning data. Practical experiments show that the estimated position obtained by this system is precise enough to be useful for the navigation of robots.

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Comer Detection in Gray Lavel Images for Wafer Die Position Recognition (웨이퍼 다이 위치 인식을 위한 명암 영상 코너점 검출)

  • 나재형;오해석
    • Journal of KIISE:Software and Applications
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    • v.31 no.6
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    • pp.792-798
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    • 2004
  • In this paper, we will introduce a new corner detector for the wafer die position recognition. The die position recognition procedure is necessary for WSCSP(Wafer Scale Chip Scale Packaging) technology, decide the accuracy of post-procedure. We present a hierarchical gray level corner detection method for the recognition of the die position from a wafer image. The new corner detector divides the corner region into many homocentric circles, and calculates the comer response and the angle of direction about each circle to get an accurate toner point. The new corner detector has a hierarchical structure so it can detect comer point more quickly than general gray level corner detector.