• Title/Summary/Keyword: coded

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Comparison of Characteristics of Gamma-Ray Imager Based on Coded Aperture by Varying the Thickness of the BGO Scintillator

  • Seoryeong Park;Mark D. Hammig;Manhee Jeong
    • Journal of Radiation Protection and Research
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    • v.47 no.4
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    • pp.214-225
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    • 2022
  • Background: The conventional cerium-doped Gd2Al2Ga3O12 (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi4Ge3O12 (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.

Low-Power Video Decoding on a Variable Voltage Processor for Mobile Multimedia Applications

  • Lee, Seong-Soo
    • ETRI Journal
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    • v.27 no.5
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    • pp.504-510
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    • 2005
  • This paper proposes a novel low-power video decoding scheme. In the encoded video bitstream, there is quite a large number of non-coded blocks. When the number of the non-coded blocks in a frame is known at the start of frame decoding, the workload of the video decoding can be estimated. Consequently, the supply voltage of very large-scale integration (VLSI) circuits can be lowered, and the power consumption can be reduced. In the proposed scheme, the encoder counts the number of non-coded blocks and stores this information in the frame header of the bitstream. Simulation results show that the proposed scheme reduces the power consumption to about 1/10 to 1/20.

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2-D MMFF Model and Performance Analysis of 2-layer coded Video Traffic Sources (2-차원 MMFF 모델을 이용한 2-계층 부호화 영상 트래픽의 모델링 및 성능 분석)

  • 안희준;노병희;김재균
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.1
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    • pp.17-32
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    • 1996
  • In this paper, a model for two-layered video traffic is proposed. The performance analysis of the proposed model and the effects of two-layer coding scehemes in ATM networks are also studied. ATM-based networks give the possibility to support image codingat variable bit rate(VBR). Two layer coding is one of the very promising methods among many proposed methods to compensate the cell loss, the major drawback in ATM networks. From the experimental data of the 2-layer coded video traffics, it is observed that traffic patterns of base layer and enhanced layer are highly correlate to each other, when constant image quality is kept. With this observation, coded two layered video traffic can be modeled as 2-dimensional Markov chain. The model well fit the real experimental data. The model was used for the analysis of the performance of statistical multiplexer with priorites in ATM networks.

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Performance Analysis of LDPC Decoding Algorithm for 3D-HDTV with Coded Marginalization in Nonbinary Channel (Coded Marginalization 기법을 활용한 비이진 채널에서 3D-HDTV의 LDPC 복호 알고리즘 성능 분석)

  • Im, Hyunho;Kwon, Kyung-Hoon;Heo, Jun
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2010.11a
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    • pp.288-290
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    • 2010
  • PAM이나 QAM과 같은 변조 방식을 이용한 비이진 채널은 BPSK 변조 방식을 사용한 이진 채널과는 다르게 심볼 정보를 이진 확률 정보로 marginalization 하는 과정에서 비이진 심볼을 구성하는 비트 정보 사이의 상관관계 정보가 손실되어 성능 저하를 야기한다. 본 논문은 차세대 3D-HDTV 시스템이 요구하는 높은 전송 효율을 확보하기 위해 사용되는 비이진 채널에 적합한 LDPC 부호화 및 복호화 알고리즘을 소개한다. 또한 GF(q)에서 정의된 비이진 BP 알고리즘이 이진 BP 알고리즘에 비해 보이는 배의 복호 복잡도를 개선하기 위한 대안으로 Coded Marginalization 기법을 제안하고 시뮬레이션을 통해 그 성능을 분석한다.

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The shape measurement of three-dimensional object by using color-coded information (색정보를 이용한 3차원 형상 측정)

  • Kim J.S.;Song C.K.;Joo B.K.;HONG J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1446-1449
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    • 2005
  • The purpose of this study is the real-time shape measurement of three-dimensional object by using color coded information. The paper relates to non-contact optical measurements of surface profiles or displacements, because of optical measurement systems are advantageous over using mechanical sensing, their relatively high speed and non-destructive capabilities. Therefore is particularly useful for three dimensional sensing which requires high horizontal and vertical resolution of measurements over a wide range thereof. Each a red, blue, green by using a inherence colors of hue value are good point.

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LVQ network for a face image recognition of the 3D (3D 얼굴 영상 인식을 위한 LVQ 네트워크)

  • 김영렬;박진성;임성진;이용구;엄기환
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.05a
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    • pp.151-154
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    • 2003
  • In this paper, we propose a method to recognize a face image of the 3D using the LVQ network. LVQ network of the proposed method, We used the front view of a face image to get to a coded light to a training data, can group a face image including the side of various angle. For an usefulness authentication of this algorithm, Various experiment which classifies a face image of the angle was the low.

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A Study about Performance of Sum-Product Decoder Considering Adaptive Bit-Loading in LDPC Coded OFDM Systems (LDPC Coded OFDM 시스템에서 적응형 비트 로딩을 고려한 Sum-Product 복호기 성능에 관한 연구)

  • Oh, Hui-Myoung;Kim, Young-Sun;Lee, Jae-Jo
    • Proceedings of the KIEE Conference
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    • 2006.07d
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    • pp.2027-2028
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    • 2006
  • 추정된 채널 정보를 바탕으로 적용하는 적응형 비트 로딩 방식은, 전력선 통신 시스템의 고속화 및 대용량 데이터 전송을 위해 최근 대두되고 있는 LDPC(Low Density Parity Check) coded OFDM 시스템에 대해, 한정된 주파수 대역과 신호 전력의 효율적 사용을 제공한다. 그러나 적응형 비트로딩 방식은 한정된 수의 일정 SNR(신호대 잡음 전력비) 구간에 대한 mapping 방식으로 적용되기 때문에 송수신 과정에서 추정된 채널 정보를 이용하는 sum-product 복호기가 채널 변화에 민감하게 반응하지 못하는 상황이 발생하며, 결국 송신단에서 채널 추정 결과를 바탕으로 선택된 SNR 범위에 대해서는 실제 수신되는 신호에 대한 SNR과의 차이가 존재하고 시스템의 성능은 그 만큼의 성능 열하로 나타나게 된다. 본 논문에서는 이러한 성능 열하 정도를 시뮬레이션을 통해 확인하였다.

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Mobile Robot Localization Based on Hexagon Distributed Repeated Color Patches in Large Indoor Area (넓은 실내 공간에서 반복적인 칼라패치의 6각형 배열에 의한 이동로봇의 위치계산)

  • Chen, Hong-Xin;Wang, Shi;Han, Hoo-Sek;Kim, Hyong-Suk
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.4
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    • pp.445-450
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    • 2009
  • This paper presents a new mobile robot localization method for indoor robot navigation. The method uses hexagon distributed color-coded patches on the ceiling and a camera is installed on the robot facing the ceiling to recognize these patches. The proposed "cell-coded map", with the use of only seven different kinds of color-coded landmarks distributed in hexagonal way, helps reduce the complexity of the landmark structure and the error of landmark recognition. This technique is applicable for navigation in an unlimited size of indoor space. The structure of the landmarks and the recognition method are introduced. And 2 rigid rules are also used to ensure the correctness of the recognition. Experimental results prove that the method is useful.

Trellis-Coded Modulation Techniques for PRS and 49-QPRS Channels (PRS 및 49-QPRS 채널의 Trellis-Coded 변조 기술)

  • 방성일;진연강
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.11
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    • pp.1743-1751
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    • 1989
  • In this paper, we consider trellis-coding techniques with the convolutional encoder R=k/(k+1) for improving the reliability of digital transimission over bandlimited noisy PRS and 49-QPRS channels. Employing the R=k/(k+1) convolutional code for the PRS channel results in over 3 dB of coding gain comparing with the baseline system. The trellis-coded 49-QPRS system can be realized by combining the 9-QPRS system with the R=1/2 convolutiona code, which can be improved by over 2dB coding gain comparing with the 9-QPRS system. In additin, we study a method of avoiding the occurance of unlimited runs of identical output to prevent operation of timing error.

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Control of Unstable Systems Concerned with the Performance Indexes and Constraints (성능지수와 제약조건을 고려한 불안정 시스템의 제어)

  • Ahn, Jong-Kap;Lee, Yun-Hung;So, Myung-Ok
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.5
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    • pp.785-790
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    • 2008
  • A technique for determining the feedback gain of the states feedback controller using a real-coded genetic algorithm(RCGA) is presented. It is concerned with the states error to the performance index of a RCGA. As for assessing the performance of the controller three performance criteria (ISE. IAE and ITAE) are adopted. And designing the controller involves a constrained optimization problem. Therefore a real-coded genetic algorithm incorporating the penalty strategy is used. The performance of the proposed method is demonstrated through a set of simulation about an inverted pendulum system.