휴대용 방사선 측정시스템의 최고값 검출 알고리즘의 설계 및 구현
Design and Implementation of Peak Detection Algorithm for Portable Radiation Measurement System
- 주제(키워드) Radiation Detector , Peak Detection Algorithm , Digital Radiation Detection
- 발행기관 아주대학교
- 지도교수 김영길
- 발행년도 2016
- 학위수여년월 2016. 2
- 학위명 박사
- 학과 및 전공 일반대학원 의용공학과정
- 실제URI http://www.dcollection.net/handler/ajou/000000021626
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Abstract Although more than 30 years has already passed since the Chernobyl nuclear accident occurred on April 26, 1986, the damage resulting from the radioactive effluent is still in progress. Even now when more than four years has passed since the occurrence of the Fukushima nuclear plant explosion accident on March 11, 2011 due to the aftermath of the great east Japan earthquake, let alone the aggregation of the damage, radiation leaks are continuing. According to a recent announcement of the Bedford Institute of Oceanography under the umbrella of the Department of Marine and Fisheries of Canada, the concentration of Cs-137 has been increasing from 3Bq/㎥(June 2012) to 0.76Bq/㎥(2013) and to 2.03Bq/㎥(2014) in seawater in the coast of Canada, several thousand kilometers away from Fukushima. This is information can be said to be a sufficient reason for the perception that South Korea cannot be guaranteed for safety against radioactivity. Therefore, the necessity of not only studies for easy detection of radioactivity but also the propagation of related information has become a pressing issue directly related to our survival and the fact that radioactivity is not only the problem of Chernobyl or Fukushima only known through reports should be perceived now. In fact, the risk of direct radiation exposure has been caused to our dietary life and if we paid just a little attention, we could find radio-active wastes as by-products of medical practice without difficulty at hospitals close to us. The moving paths of radioactive substances predicted based on oc-ean currents and marine debris convergence are expected to be conti-nuously accumulated and consequences of contamination increase over time. The possibility of radiation exposure of all mankind will increase and the studies and supply of high performance state-of-the-art d-etectors of radiation exposure can be also said to be urgent. As a solution for such problems, this researcher studied methods of improving existing detectors using analog boards and proposes a sof-tware algorithm for prevention of not only the degradation of detection performance due to noises, etc. occurring on the analog board but also the occurrence of unnecessary power consumption due to the operation of the analog board and the phenomenon of degradation of detector performance due to the signals inevitably ignored in the pro-cess of pulse shaping in the analog board signal process.
more목차
1 Introduction 1
2 Related Works 7
2.1 Type & Principle of Radiation Detector 7
2.1.1 Radiation 7
2.1.2 Type of Radiation 9
2.1.2.1 Alpha Rays 9
2.1.2.2 Beta Rays 9
2.1.2.3 Gamma Rays 9
2.1.2.4 X Rays 10
2.1.2.5 Neutron Rays 10
2.1.3 Type of Radiation Detector 10
2.1.3.1 Measurement of Dose 11
2.1.3.2 Measurement of the Absorbed Dose 11
2.1.3.3 Measurement of Dose Equivalent 11
2.1.4 Dimension of Radiation 12
2.1.4.1 Irradiation Dose 12
2.1.4.2 Absorbed Dose 13
2.1.4.3 Equivalent Dose 13
2.1.4.4 Effective Dose 14
2.1.5 Principle of Radiation Detector 15
2.1.5.1 Detectors Using Ionization Reactions 15
2.1.5.2 Detectors Using Excitation 17
2.1.5.3 Other Detectors 18
2.2 Gamma(γ) Radiation 18
2.2.1 Overview 18
2.2.2 Gamma(γ)-ray 19
2.2.3 Compton Scattering 20
2.2.4 Pair Production 22
2.3 Using Photoelectric Effect Peak Detection System 23
2.3.1 Overview 23
2.3.2 System Block Diagram 25
2.3.3 Scintillation Sensor 25
2.3.4 Analog Board 27
2.3.4.1 Overview 27
2.3.4.2 Amplifier 29
2.3.4.3 Pulse Shaper 30
2.3.4.4 Pulse Detector 35
2.3.4.5 Peak Holder 37
2.3.5 ARM Cortex-A9 Android Digital Platform 39
2.3.5.1 Overview 39
2.3.5.2 Coretex A9 Architecture 40
2.3.5.3 Digital Platform Supporting Accessories 43
2.3.5.4 ADC Process 44
2.3.5.5 Energy Mapping 45
2.3.5.6 Energy Spectrum 46
2.3.6 Digital Signal Process System 50
2.3.6.1 Overview 50
2.3.6.2 DP5G System Block Diagram 51
2.3.6.3 Analog Prefilter 53
2.3.6.4 Digital Processor 54
3 Proposed Peak Detection Algorithm 58
3.1 Overview 58
3.2 Digital Portable Radioactivity Detection System 61
3.2.1 Comparison with Analog Systems 61
3.2.2 Comparison with Digital Systems 62
3.2.3 Digital System Software Architecture 63
3.2.3.1 Overview 63
3.2.3.2 Data Part Software 64
3.2.3.3 Data Part Software Flow Chart 67
3.2.3.4 Control Part Software 68
3.2.3.5 Energy Mapping Algorithm 68
3.3 Proposed Peak Detection Algorithm 72
3.3.1 Using Peak Detection Algorithm 72
3.3.2 Principle Peak Detection Algorithm 78
3.3.2.1 Peak Detection Algorithm Flow Chart 78
3.3.2.2 Initialize 79
3.3.2.3 Remove Negative Values 81
3.3.2.4 Increase(UP) Data Value Part 83
3.3.2.5 Decrease(Down) Data Value Part 85
3.3.2.6 Determine of Down_Counter Number 90
4 Experiment and Analysis 96
4.1 Simulation 96
4.1.1 Overview 96
4.1.2 Sensor Signal Quantification 96
4.1.3 Sensor Signal ADC Sampling (Down_Counter=10) 97
4.1.3.1 Simulation (ADC Sampling=500ns) 97
4.1.3.2 Simulation (ADC Sampling=1) 99
4.1.3.3 Simulation (ADC Sampling=2) 101
4.1.4 Determine Of Down_Counter Number 103
4.1.4.1 Role Of Down_Counter Number 103
4.1.4.2 Simulation (Down_Counter Number=10) 104
4.1.4.3 Simulation (Determine of Down_Counter Number) 105
4.2 Experiment 108
4.2.1 Experiment Environment 108
4.2.2 Experiment Equipment 109
4.2.2.1 Gamma-Ray Sample Source 109
4.2.2.2 Scintillator Sensor 109
4.2.2.3 Digital Platform 110
4.3 Experiment and Analysis 112
4.3.1 Experiment Results of Natural Radiation 112
4.3.2 Experiment Results of Ba-133 113
4.3.3 Experiment Results of Na-22 114
4.3.4 Experiment Results of Cesium-137 115
4.3.5 Experiment Results of Multi Nuclide Radiation 116
5 Result 118
References 120
Summary(in Korean) 126
