• Title/Summary/Keyword: 검출기

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Impulse Noise Removal Using Noise Detector and Total Variation Optimization (잡음 검출기와 총변량 최적화를 이용한 영상의 임펄스 잡음제거)

  • Lee Im-Geun
    • The Journal of the Korea Contents Association
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    • v.6 no.4
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    • pp.11-18
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    • 2006
  • A new algorithm for removing salt and pepper impulse noise in image using impulse noise detector and total variation optimization is presented. The proposed two types of noise detectors which are based on the adaptive median filter, can detect impulse noise with high accuracy while reducing the probability of detecting image details as impulses. And the detectors maintain its performance independent of noise density. For removing impulses, total variation optimization is applied only to those detected noise candidate to reduces unnecessary computation. The proposed approach successfully remove impulse noise while preserving image details.

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Novel control scheme for the absence of the thermoelectric(TEC) of infrared detector in an Uncooled thermal system (비냉각 열상시스템에서의 적외선 검출기의 열전소자(TEC) 부재에 대한 효율적인 제어기법)

  • Kim, Yong-Jin;Seo, Jae-Gil;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.10
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    • pp.2335-2340
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    • 2012
  • The detector is an uncooled detector system that functions inside the thermoelectric cooler (TEC) equipped with features instead of the cooler. The function of the thermoelectric device to control the temperature of the detector based on a function of temperature to prevent degradation of image quality to perform the role, the latest technology trend by removing the thermoelectric device size, cost a lot of effort to reduce has been studied. In this paper, It would be proposed of the actual test result using real chamber environment of for the best TECless algorithm as to minimize the degradation of image quality and obtain the low price of the uncooled detector.

Ground based interferometric gravitational wave detector and its technologies

  • Park, June Gyu;Kim, Chang-Hee;Lee, Sungho;Kim, Yunjong;Seong, Hyeon Cheol;Jeong, Ueejeong;Je, Soonkyu
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.2
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    • pp.60.1-60.1
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    • 2021
  • 현재 중력파 관측은 레이저 간섭계 기반의 중력파 검출기를 통해 이루어지고 있고 검출기 성능이 개선되고 안정화 되어 초기 설계 사양 이상의 관측감도를 확보하였다. 이제 레이저 간섭계 기반의 중력파 관측 기술은 중력파 관측 가능성의 유무를 넘어 차세대 중력파 검출기의 건설을 앞당기는 수준이 되었으며 해외에서는 중력파 검출 기술을 선도하기 위한 공격적인 투자가 이루어 지고 있다. 이 발표에서는 현재 운영중인 레이저 간섭계 기반의 중력파 검출기의 중력파 검출 원리와 실제 중력파 검출기에서 사용되는 관련 핵심 기술들을 소개하고자 한다. 단순히 특정 분야의 일부 기술이 아닌 중력파 검출기 건설에 사용된 재료, 광학, 기계공학, 전자, 통신 등 다양한 분야의 기술을 소개하고 실제 중력파 검출기 관련 연구에 참여할 수 있는 연구 주제를 소개하고자 한다.

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A Study for Analysis of Image Quality Based on the CZT and NaI Detector according to Physical Change in Monte Carlo Simulation (CZT와 NaI 검출기 물질 기반 물리적 변화에 따른 영상의 질 분석에 관한 연구: 몬테카를로 시뮬레이션)

  • Ko, Hye-Rim;Yoo, Yu-Ri;Park, Chan-Rok
    • Journal of the Korean Society of Radiology
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    • v.15 no.5
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    • pp.741-748
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    • 2021
  • In this study, we evaluated image quality by changing collimator length and detector thickness using the Geant4 Application for Tomographic Emission (GATE) simulation tool. The gamma camera based on the Cadimium Zinc Telluride (CZT) and NaI detectors is modeled. In addition the images were acquired by setting 1, 2, 3, 4, 5, and 6 cm collimator length and 1, 3, 5, and 7 mm detector thickness using point source and phantom, which is designed by each diameter (4.45, 3.80, 3.15, 2.55 mm) with 447, 382, 317, and 256 Bq. The sensitivity (cps/MBq) for point source, and signal to noise ratio (SNR) and profile for phantom at the 4.45 mm by drwan the region of interests were used for quantitative analysis. Based on the results, the sensitivity according to collimator length is 2.3 ~ 48.6 cps/MBq for CZT detector, and 1.8 ~ 43.9 cps/MBq for NaI detector. The SNR using phantom is 3.6~9.8 for CZT detector, and 2.9~9.5 for NaI detector. As the collimator length is increased, the image resolution is also improved according to profile results based on the CZT and NaI detector. In addition, the senistivity for detector thickness is 0.04 ~ 0.12 cps/MBq for CZT detector, and 0.03 ~ 0.11 cps/MBq. The SNR using phnatom is 7.3~9.8 count for CZT detector, and 5.9~9.5 for NaI detector. As the detector thickness is increased, the image resolution is decreased according to profile results based on the CZT and NaI detector due to scatter ray. In conclusion, we need to set the geometric material such as detector and collimator to acuquire suitable image quality in nuclear medicine.

Image Quality Evaluation of CsI:Tl and Gd2O2S Detectors in the Indirect-Conversion DR System (간접변환방식 DR장비에서 CsI:Tl과 Gd2O2S의 검출기 화질 평가)

  • Kong, Changgi;Choi, Namgil;Jung, Myoyoung;Song, Jongnam;Kim, Wook;Han, Jaebok
    • Journal of the Korean Society of Radiology
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    • v.11 no.1
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    • pp.27-35
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    • 2017
  • The purpose of this study was to investigate the features of CsI:Tl and $Gd_2O_2S$ detectors with an indirect conversion method using phantom in the DR (digital radiography) system by obtaining images of thick chest phantom, medium thickness thigh phantom, and thin hand phantom and by analyzing the SNR and CNR. As a result of measuring the SNR and CNR according to the thickness change of the subject, the SNR and CNR were higher in CsI:Tl detector than in $Gd_2O_2S$ detector when the medium thickness thigh phantom and thin hand phantom were scanned. However, when the thick chest phantom was used, for the SNR at 80~125 kVp and the CNR at 80~110 kVp in the $Gd_2O_2S$ detector, the values were higher than those of CsI:Tl detector. The SNR and CNR both increased as the tube voltage increased. The SNR and CNR of CsI:Tl detector in the medium thickness thigh phantom increased at 40~50 kVp and decreased as the tube voltage increased. The SNR and CNR of $Gd_2O_2S$ detector increased at 40~60 kVp and decreased as the tube voltage increased. The SNR and CNR of CsI:Tl detctor in the thin hand phantom decreased at the low tube voltage and increased as the tube voltage increased, but they decreased again at 100~110 kVp, while the SNR and CNR of $Gd_2O_2S$ detector were found to decrease as the tube voltage increased. The MTF of CsI:Tl detector was 6.02~90.90% higher than that of $Gd_2O_2S$ detector at 0.5~3 lp/mm. The DQE of CsI:Tl detector was 66.67~233.33% higher than that of $Gd_2O_2S$ detector. In conclusion, although the values of CsI:Tl detector were higher than those of $Gd_2O_2S$ detector in the comparison of MTF and DQE, the cheaper $Gd_2O_2S$ detector had higher SNR and CNR than the expensive CsI:Tl detector at a certain tube voltage range in the thick check phantom. At chest X-ray, if the $Gd_2O_2S$ detector is used rather than the CsI:Tl detector, chest images with excellent quality can be obtained, which will be useful for examination. Moreover, price/performance should be considered when determining the detector type from the viewpoint of the user.

Feasibility Study of Parallel- Plate Detector Using Dielectric film for 6 MV X-ray (6MV X-선 검출특성 조사를 위하여 유전체 필름을 이용하여 제작한 평행판 검출기의 유용성)

  • 조문준;김용은;이병용;김정기;임상욱;김현수;김기환
    • Progress in Medical Physics
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    • v.15 no.2
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    • pp.105-111
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    • 2004
  • The parallel plate detector with dielectric film for dosimetry was designed to measure detection characteristic of 6 MV X-ray with medical linear accelerator. PTFE film was inserted into FEP films that are made by two one-side metal coated materials for ion source. The thicknesses of PTFE dielectric film was 100 ${\mu}{\textrm}{m}$ and the thickness of FEP dielectric film was 100 ${\mu}{\textrm}{m}$, respectively. This detector was fixed by two acrylic plate for physical hardness ad geometrical consistency. The geometrical condition for measurement with parallel-plate for detector was below; SSD=100 cm and the 5 cm depth between detector and phantom surface The major parameter of detector characteristics such as zero drift current, leakage current, charge response by applied voltage, reproducibility, linearity, TMR measurement, dose rate effect were measured. The zero drift currents are 8.3 pA and leakage currents are 10 pA. The charge response of applied voltage is showing linearity in 414 voltage. The measurement deviation of reproducibility in this detector is within 1% for dose and the linearity of applied dose shows in this detector. The TMR curves in phantom between this parallel plate detector and reference detector are matched within 3% deviation from maximum dose depth to 7.5 cm depth. It is considered that this dosimetric system is satisfactory for the purpose of the constancy check of the 6 MV x-ray from medical linear accelerator.

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Hybrid Iterative Detection Algorithm for MIMO Systems (다중 안테나 시스템을 위한 Hybrid Iterative 검출 기법)

  • Kim, Sang-Heon;Shin, Myeong-Cheol;Kim, Kyeong-Yeon;Lee, Chung-Yong
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.4 s.316
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    • pp.117-122
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    • 2007
  • For multiple antenna systems, we consider the hybrid iterative detection of the maximum a posteriori probability(MAP) detection and the linear detection such as the minimum-mean-square-error(MMSE) filtering with soft cancelation. We devise methods to obtain both the lower complexity of the linear detection and the superior performance of the MAP detection. Using the a prior probability of the coded bit which is extrinsic of the outer decoder, we compute the threshold of grouping and determine the detection scheme symbol by symbol. Through the simulation results, it is shown that the proposed receiver obtains the superior performance to the MMSE detector and the lower complexity than the MAP detector.

속도 검출기 없는 유도전동기의 고성능 all-digital drive system의 구현

  • 유호선;이상훈
    • ICROS
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    • v.3 no.3
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    • pp.36-48
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    • 1997
  • 본 원고에서는 극 좌표계를 기준으로 하여 추정기를 구성함으로써 속도 검출기가 없는 유도전동기의 회전자 자속 및 회전 속도를 정확히 추정해 내고, 다시 이 정보를 이용하여 유도전동기를 고성능으로 제어할 수 있는 드라이브 시스템의 구현 과정과 이를 이용한 간단한 실험 결과에 대하여 소개하였다. 본 원고에서 제시한 몇가지의 실험 결과들은 소프트웨어의 알고리즘에 의하여 전동기의 회전축에 부착된 속도 검출기는 충분히 대치될 수 있음을 말해주는 것이므로, 속도 검출기가 가격과 내구성 등에서 실제적으로 산업 현장에 적용하기에 많은 문제점을 안고 있다는 점을 감안할 때 그 유용성을 입증하는 것이다.

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A Study on the Degradation Detector for Transmission Line (송전 선로용 열화 검출기 연구)

  • Park, Geon-Ho
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2015.07a
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    • pp.297-298
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    • 2015
  • 본 연구에서는 기존 방식인 인력에 의한 송전 선로 점검 방식을 대체할 수 있는 로봇 기술이 적용된 열화 검출기의 제작을 위하여 송전 선로의 부식 메커니즘과 물성 변화에 대해 고찰하였다. 이를 통해 송전 선로의 열화에 의한 기계적 결함과 전기적 특성변화의 확인을 위한 과학적인 접근 방법을 제시하여 송전 선로의 열화를 포함한 외부 이상을 검출할 수 있는 열화 검출기에 대한 연구를 수행하였다.

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For the Li Drifted Germanium Detector (Li drifted Ge 검출기에 관해서)

  • 함창식
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.4 no.2
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    • pp.16-21
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    • 1967
  • This report describes actual fabrication mehod of Li drifted Ge detector. The gamma-ray spectrum from Cl(n, r) reaction measured by this Li drifted Ge detector are also shown. Energy resolution(FWHM) of this Li drifted Ge detector is 4.5KeV at the 122KeV( ), and 10KeV a the 1333KeV( ) respectively.

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