• Title/Summary/Keyword: 어레이 합성기법

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A Compensation for Localization Error in WFS using Precedence Effect (선행 효과를 이용한 음장 합성 기법의 음상정위 보정)

  • Choi, Keunwoo;Park, Tae Jin;Seo, Jeongil;Kang, Kyeongok
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2012.11a
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    • pp.57-59
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    • 2012
  • 음장 합성 기법은 라우드스피커 어레이를 사용하여 보다 넓은 청취 공간을 제공하는 음향 재생 기법이다. 이를 이용한 렌더링 성능을 좌우하는 요소 중 하나로 스피커의 간격이 있다. 스피커의 간격은 앨리어싱 주파수와 직접적인 관계가 있으며 간격이 좁을수록 높은 성능을 보인다. 그런데 좁은 간격의 어레이를 사용하는 경우 라우드스피커의 저역 한계 주파수가 높아지게 마련이며 따라서 필수적으로 저주파 대역을 위한 서브 우퍼를 사용해야 한다. 이런 경우에 서브 우퍼에 의한 음상정위 오류가 있을 수 있다. 본 논문에서는 선행 효과를 이용하여 이 문제에 대한 해결방안을 제시한다.

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Performance Characteristics of Subband Adaptive Array Antenna using Kalman Algorithm (Kalman 알고리즘에 의한 대역분할. 합성형 어댑티브 어레이 안테나의 동작 특성)

  • 박재성;오경석;주창복;박남천;정주수
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.3 no.3
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    • pp.501-507
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    • 1999
  • At the mobile unit for adaptation the propagation environment, it is necessity to adapt very fast the weight coefficient vector of adaptive array antenna In this paper, for the BPSK and BFSK signals with S/I=2, S/N=10 subband adaptive array signal processing method to the linear array antenna using the LMS & the Kalman filter algorithm is proposed. For the 4 elements equidistance linear array antenna systems LMS and Kalman algorithms with subband adaptive instruction principles using the subband signal processing method are adopted and the computer simulation results to the constant amplitude envelope signals such as BPSK or BFSK can be seen that the convergence characteristics of directional patterns and the signal following characteristics are more fast and stable.

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Real-Time 3D Ultrasound Imaging Method Using a Cross Array Based on Synthetic Aperture Focusing: I. Spherical Wave Transmission Approach (합성구경 기반의 교차어레이를 이용한 실시간 3차원 초음파 영상화 기법 : I. 구형파 송신 방법)

  • 김강식;송태경
    • Journal of Biomedical Engineering Research
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    • v.25 no.5
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    • pp.391-401
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    • 2004
  • 3D imaging systems using 2D phased arrays have a large number of active channels, compelling to use a very expensive and bulky beamforming hardware, and suffer from low volume rate because, in principle, at least one ultrasound transmit-receive event is necessary to construct each scanline. A high speed 3D imaging method using a cross array proposed previously to solve the above limitations can implement fast scanning and dynamic focusing in the lateral direction but suffer from low resolution except at the fixed transmit focusing along the elevational direction. To overcome these limitations, we propose a new real-time volumetric imaging method using a cross array based on the synthetic aperture technique. In the proposed method, ultrasound wave is transmitted successively using each elements of an 1D transmit array transducer, one at a time, which is placed along the elevational direction and for each firing, the returning pulse echoes are received using all elements of an 1D receive array transducer placed along the lateral direction. On receive, by employing the conventional dynamic focusing and synthetic aperture method along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. In addition, in the proposed method, a volume of interest consisting of any required number of slice images, can be constructed with the same number of transmit-receive steps as the total number of transmit array elements. Computer simulation results show that the proposed method can provide the same and greatly improved resolutions in the lateral and elevational directions, respectively, compared with the 3D imaging method using a cross array based on the conventional fixed focusing. In the accompanying paper, we will also propose a new real-time 3D imaging method using a cross array for improving transmit power and elevational spatial resolution, which uses linear wave fronts on transmit.

Real-Time 3D Ultrasound Imaging Method Using a Cross Array Based on Synthetic Aperture Focusing: II. Linear Wave Front Transmission Approach (합성구경 기반의 교차어레이를 이용한 실시간 3차원 초음파 영상화 기법 : II. 선형파면 송신 방법)

  • 김강식;송태경
    • Journal of Biomedical Engineering Research
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    • v.25 no.5
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    • pp.403-414
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    • 2004
  • In the accompanying paper, we proposed a real. time volumetric imaging method using a cross array based on receive dynamic focusing and synthetic aperture focusing along lateral and elevational directions, respetively. But synthetic aperture methods using spherical waves are subject to beam spreading with increasing depth due to the wave diffraction phenomenon. Moreover, since the proposed method uses only one element for each transmission, it has a limited transmit power. To overcome these limitations, we propose a new real. time volumetric imaging method using cross arrays based on synthetic aperture technique with linear wave fronts. In the proposed method, linear wave fronts having different angles on the horizontal plane is transmitted successively from all transmit array elements. On receive, by employing the conventional dynamic focusing and synthetic aperture methods along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. Mathematical analysis and computer simulation results show that the proposed method can provide uniform elevational resolution over a large depth of field. Especially, since the new method can construct a volume image with a limited number of transmit receive events using a full transmit aperture, it is suitable for real-time 3D imaging with high transmit power and volume rate.

An Adaptive Beamforming Algorithm for the LMS Array Problem (LMS어레이의 문제점을 고려한 적응 빔 형성 알고리듬)

  • Kwag, Young-Kil
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.10
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    • pp.1263-1273
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    • 1988
  • An adaptive nulling technique is presented to synthetically overcome the integrated problems associated with the conventional LMS array in the performances of jammer rejection, convergence rate, misadjustment, and reference signal generation. The proposed method is to remove the target signal from the array input and to eliminate the reference signal prior to minimization processing. The algorithm is constrained to the residue noise level in adaptive processor. Analysis shows effectiveness of the algorithm for coherent and/or incoherent interference rejection, wide dynamic range of convergence factor, rapid adaptation rate, and small mean square error. Simulation results confirm the theoretical prediction.

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A New SoC Platform with an Application-Specific PLD (전용 PLD를 가진 새로운 SoC 플랫폼)

  • Lee, Jae-Jin;Song, Gi-Yong
    • Journal of the Institute of Convergence Signal Processing
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    • v.8 no.4
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    • pp.285-292
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    • 2007
  • SoC which deploys software modules as well as hardware IPs on a single chip is a major revolution taking place in the implementation of a system design, and high-level synthesis is an important process of SoC design methodology. Recently, SPARK parallelizing high-level synthesis software tool has been developed. It takes a behavioral ANSI-C code as an input, schedules it using code motion and various code transformations, and then finally generates synthesizable RTL VHDL code. Although SPARK employs various loop transformation algorithms, the synthesis results generated by SPARK are not acceptable for basic signal and image processing algorithms with nested loop. In this paper we propose a SoC platform with an application-specific PLD targeting local operations which are feature of many loop algorithms used in signal and image processing, and demonstrate design process which maps behavioral specification with nested loops written in a high-level language (ANSI-C) onto 2D systolic array. Finally the derived systolic array is implemented on the proposed application-specific PLD of SoC platform.

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Investigation of Digital Filter Design using Improved Simulated-Annealing Technique (개선된 시뮬레이티드어닐링 기법에 의한 디지탈필터 설계의 고찰)

  • Song, Nag-Un;Yun, Bok, Sik
    • The Transactions of the Korea Information Processing Society
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    • v.2 no.1
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    • pp.106-118
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    • 1995
  • In this work, the optimized design methodology in high-level synthesis related with scheduling and hardware allocation is developed by simulated annealing technique effectively modified . Applying this method to digital filter design, the optimized tradeoff problem of speed and hardware costs in pipelined digital filter case and array digital filter case are investigated. While, it is confirmed that the suggested method gives the improved cost function value faster and can be used in complicated digital filter design.

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Signal Processing in Medical Ultrasound B-mode Imaging (의료용 초음파 B-모드 영상을 위한 신호처리)

  • Song, Tai-Kyong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.6
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    • pp.521-537
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    • 2000
  • Ultrasonic imaging is the most widely used modality among modern imaging device for medical diagnosis and the system performance has been improved dramatically since early 90's due to the rapid advances in DSP performance and VLSI technology that made it possible to employ more sophisticated algorithms. This paper describes "main stream" digital signal processing functions along with the associated implementation considerations in modern medical ultrasound imaging systems. Topics covered include signal processing methods for resolution improvement, ultrasound imaging system architectures, roles and necessity of the applications of DSP and VLSI technology in the development of the medical ultrasound imaging systems, and array signal processing techniques for ultrasound focusing.

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Performance Analysis of FFTSA Method in the Water Environment Using Conformal Towed Acoustic Array (왜곡된 형태의 견인 음향 배열 기법을 적용한 수중환경하에서의 FFTSA 기법 성능분석)

  • 최주평;이원철
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.8
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    • pp.44-57
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    • 2001
  • This paper analyses the performance of FFTSA (Fast Fourier Transform Synthetic Aperture) in the effects of temporal coherence and oscillatory towed course, which is one of the techniques for passive synthetic aperture SONAR process using linearly distributed towed array. Also this paper proposes the FFTSA technique using towed array having conformal shape to alleviate the performance degradation for estimating the incident angle under inconsistent under water environments. And this paper analyses the performance of the proposed FFTSA technique making use of conformal structure throughout exhaustive computer simulations.

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Light Field Angular Super-Resolution Algorithm Using Dilated Convolutional Neural Network with Residual Network (잔차 신경망과 팽창 합성곱 신경망을 이용한 라이트 필드 각 초해상도 기법)

  • Kim, Dong-Myung;Suh, Jae-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.12
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    • pp.1604-1611
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    • 2020
  • Light field image captured by a microlens array-based camera has many limitations in practical use due to its low spatial resolution and angular resolution. High spatial resolution images can be easily acquired with a single image super-resolution technique that has been studied a lot recently. But there is a problem in that high angular resolution images are distorted in the process of using disparity information inherent among images, and thus it is difficult to obtain a high-quality angular resolution image. In this paper, we propose light field angular super-resolution that extracts an initial feature map using an dilated convolutional neural network in order to effectively extract the view difference information inherent among images and generates target image using a residual neural network. The proposed network showed superior performance in PSNR and subjective image quality compared to existing angular super-resolution networks.