• Title/Summary/Keyword: SIGNAL SCAN

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Implementation of Nonlinear SVM for HD Projection TV (HD Projection TV를 위한 비선형 SVM 회로의 구현)

  • Lee, Gwang-Sun;Gwon, Yong-Dae;Lee, Geon-Il;Song, Gyu-Ik;Choe, Deok-Gyu;Han, Chan-Ho;Kim, Eun-Su
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.38 no.2
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    • pp.191-198
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    • 2001
  • As a method to compensate the deterioration of the picture quality which was caused by beam profile characteristic in the CRT and the projection screen of HD projection TV, a linear scan velocity modulation(SVM) method has been employed, whose modulation velocity is linearly proportional to the variation in the video signal amplitude. However, the effect of picture quality improvement is not uniform with video signal amplitude in the linear SVM. In this paper, for the optimum SVM effect, we analyze the beam profile characteristic on the HD projection screen and we analyze the SVM effect as function of the differentiated pulse width, the differentiated pulse amplitude and the input signal amplitude. Finally we confirm that the nonlinear SVM method is necessary to get uniform image compensation in the HD projection TV, and we implement the nonlinear SVM circuit. The performance of the realized SVM circuit with nonlinear amplitude transfer characteristic is confirmed as uniform improvements in picture quality.

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One-Sided Nondestructive Evaluation of CFRP Composites By Using Ultrasonic Sound (초음파를 이용한 CFRP 복합재의 일방향 비파괴 평가)

  • Im, Kwang-Hee;Zhang, Gui-Lin;Choi, Sung-Rok;Ye, Chang-Hee;Ryu, Je-Sung;Lim, Soo-Hwan;Han, Min-Gui;Hsu, David K.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.1
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    • pp.47-52
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    • 2011
  • It is well known that stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences their properties. Ultrasonic NDE of composite laminates is often based on the backwall echoes of the sample. A pair of such transducers was mounted in a holder in a nose-to-nose fashion to be used as a scanning probe on composites. Miniature potted angle beam transducers were used (Rayleigh waves in steel) on solid laminates of composites. Experiments were performed to understand the behavior of the transducers and the nature of the waves generated in the composite (mode, wave speed, angle of refraction). C-scan images of flaws and impact damage were then produced by combining the pitch-catch probe with a portable manual scanner known as the Generic Scanner ("GenScan"). The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to fiber orientation of the CFRP composites, including low level porosity, ply waviness, and cracks. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with numerical results and one-side ultrasonic measurement might be very useful to detect the defects.

A Study on the optimization of overlap scanning method for the enhancement of display quality in LC Displays (액정 표시기의 화질 향상을 위한 중첩구동방식의 최적화에 관한 연구)

  • 최선정;김용득
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.32B no.10
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    • pp.1280-1285
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    • 1995
  • In this paper the optimized overlap driving scheme for improving the reduction problem of the operating voltage range occured by the overlap driving scheme proposed precedently and increasing the contrast ratio of screen image in the simple matrix LCDs is proposed. The characteristic estimation of the proposed method was performed in a condition that the number of scan electrodes was 120 and the threshold voltage of LC pixel was 2V and the overlap rate of scan signal was varied from 0% to 40% . As a result of estimation compared with the overlap driving scheme proposed precedently, this new method was certified as a method which it could increase the operating voltage range of the LC pixel by 16% in 20% overlap condition and it's operating voltage range was also increased very much with the increase of the overlap rate. Consequently this newly proposed method was certified as a method which it could maintain the improvement effect of the operating characteristics obtained by the overlap driving scheme proposed precedently with the big improvement in the contrast ratio of screen image.

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Measurement on Pipe Detectability of the GPR Consisting of Self-Designed Antenna (자체 설계한 안테나로 구성된 GPR의 파이프 검출능력에 관한 측정)

  • 현승엽;김상욱;김세윤
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.3
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    • pp.19-26
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    • 1999
  • The detectability of pipes buried in dry sand is investigated by using the GPR with self-designed bow-tie antenna. The antennas are covered with shielding structures to reduce the direct-coupling between the transmitting and receiving antennas. The ringing, due to finite length of the antenna, is decreased by performing resistive termination at the ends of the antennas. It is shown that without additional signal processing, the presence of various buried targets can be found by discriminating hyperbolic pattern in B-scan data.

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Resonution Enhancement of Ultrasonic B-Scan Images by Deconvolution (횡축 디콘벌루션에 의한 초음파 B 스캔 연상의 해상력 향상)

  • Jeong, Joon-Young;Chin, Young-Min;Woo, Kwang-Bang
    • Proceedings of the KIEE Conference
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    • 1988.11a
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    • pp.445-449
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    • 1988
  • Digital processing of measured data offers a powerful means to improve the resolution and quality of ultrasonic imaging. The present research demonstrates that filtering typical B-scan images using Wiener filter enhances lateral resolutions by more than 50 percent. The filter is operated using the measured signal amplitude across the transmitter beam and the beam with. It is optimized for low noise and high resolution By an empirical approach. This bethod for lateral filtering produces a very useful result for the line images with high interference by neighboring lines.

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Analysis of sampling noise effect of Interferometer on FTIR Spectrometer (FTIR 분광용 간섭계의 샘플링 잡음 영향 분석)

  • Bae, Hyo-Wook;Park, Do-Hyun;Ra, Sung-Woong;Choi, Seung-Ki
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.44 no.4
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    • pp.10-17
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    • 2007
  • FTIR(Fourier Transform Infrared) spectrometry is a useful method to obtain infrared spectra of materials in gas phase by registering the interferogram of a target material using an interferometer, and then performing a Fourier transform on the interferogram to obtain the spectrum. In this paper, sampling noise effect on signal processing of the rapid scan interferometer was studied with relation to sampling the interferogram points at the improper location and empirically verified.

Inspection of Cracks on the Express Train Wheel Using a High Speed Scan Type Magnetic Camera (초고속 스캔형 자기카메라에 의한 고속열차 차륜 탐상)

  • Lee, Jin-Yi;Hwang, Ji-Seong;Kwon, Seok-Jin;Seo, Jung-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.11
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    • pp.943-950
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    • 2008
  • A novel nondestructive testing (NDT) system, which is able to detect a crack with high speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. This paper proposes a high speed scan type magnetic camera, which uses the multiple amplifying circuits and the crack indicating pulse output system. The linearly integrated Hall sensors are arrayed in parallel, and the Hall voltages from each sensor in the scanning direction are obtained and amplified. High-speed NDT can be achieved by using the exclusive analog-digital converter and micro-processor because the ${\partial}\;V_H/\;{\partial}$ x value, which provides the most important crack information, can be obtained by buffering and calculating. The effectiveness of the novel method was verified by examine using cracks on the wheel specimen model.

A Development of Computer Controlled 5 Axis Ultrasonic Testing System (컴퓨터제어식 5축 자동초음파탐상장치의 개발)

  • Kim, Y.S.;Kim, J.G.;Park, J.C.;Kim, N.I.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.10 no.2
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    • pp.32-37
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    • 1990
  • A computer controlled 5 axis ultrasonic testing system is developed in order to detect flaws in special parts with complex shape. The various kinds of ultrasonic test can be performed automatically using computer program which was developed by DHI(Daewoo Heavy Industries Ltd.). By use of this computer program, the detector location can be programed and the amplitude signal of echo can be processed digitally. The test results can be plotted graphically on a high resolution display monitor in real time base. The test data can be also saved in magnetic memory devices(HDD or FDD) as well as in the form of hard copy through color printer. The computer software contains c- scan, c+a scan processing programs as well as statistical analysis for test data.

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Two-Dimensional Numerical Modeling and Simulation of Ultrasonic Testing

  • Yim, Hyun-June;Baek, Eun-Sol
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.6
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    • pp.649-658
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    • 2002
  • As an attempt to further improve the reliability and effectiveness of ultrasonic testing (UT), a two-dimensional numerical simulator of UT was developed. The simulator models the wave medium (or test object) using the mass-spring lattice model (MSLM) that consists of mass-points and springs. Some previous simulation results, obtained by using MSLM, are briefly reviewed in this paper, for propagation, reflection, and scattering of ultrasonic waves. Next, the models of transmitting and receiving piezoelectric transducers are introduced with some numerical results, which is a main focus of this paper. The UT simulator, established by combining the transducer models with the MSLM, was used to simulate many UT setups. In this paper, two simple setups are considered as examples, and their simulated A-scan signals are discussed. The potential of the MSLM, transducer models, and the UT simulator developed in this study to be used in the actual UT is confirmed.

Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.381-386
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    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.