• Title/Summary/Keyword: 고속퓨리에 변환

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Fast Image Restoration Using Boundary Artifacts Reduction method (경계왜곡 제거방법을 이용한 고속 영상복원)

  • Yim, Sung-Jun;Kim, Dong-Gyun;Shin, Jeong-Ho;Paik, Joon-Ki
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.6
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    • pp.63-74
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    • 2007
  • Fast Fourier transform(FFT) is powerful, fast computation framework for convolution in many image restoration application. However, an actually observed image acquired with finite aperture of the acquisition device from the infinite background and it lost data outside the cropped region. Because of these the boundary artifacts are produced. This paper reviewed and summarized the up to date the techniques that have been applied to reduce of the boundary artifacts. Moreover, we propose a new block-based fast image restoration using combined extrapolation and edge-tapering without boundary artifacts with reduced computational loads. We apply edgetapering to the inner blocks because they contain outside information of boundary. And outer blocks use half-convolution extrapolation. For this process it is possible that fast image restoration without boundary artifacts.

Performance of Spectrum Sensing for ATSC DTV Signals (ATSC DTV 신호 검출 성능)

  • Lee, So-Young;Kim, Eun-Cheol;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.3
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    • pp.167-172
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    • 2010
  • In this paper, we analyze and simulate the performance of a pilot signal detection algorithm based on fast Fourier transform (FFT) for several system parameters in order to detect advanced television system committee digital television (ATSC DTV) signals. Requirements for detecting DTV signals are analyzed. And the detection performance is compared according to sensing frequency and time. Form the simulation results, it is confirmed that the signal detection performance increases as the sensing frequency rises. The results of this paper can be applied for implementing cognitive radio (CR) systems in the frequency band of DTV signals.

Introduction of Surface Current Measurement Based on X-band Radar (X-밴드 레이더 기반 표층해류 계측 기법 소개)

  • Na-Yun Kang;Jose Carlos Nieto-Borge;Young-Jun Yang
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2022.06a
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    • pp.424-425
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    • 2022
  • This paper introduces X-band radar-based surface current measurement technique. A marine X-band radar used for navigation was installed at Sokcho Beach to collect surface current data in real time. Based on this, in order to verify the accuracy of the measurement of surface current (Current speed), the Korea Hydrographic and Oceanographic Agency Marine observation buoy compared it with the data. Data collected from January 2022 were compared and as a result the possibility of surface current(Current speed) measurement using radar confirmed.

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A New Tempo Feature Extraction Based on Modulation Spectrum Analysis for Music Information Retrieval Tasks

  • Kim, Hyoung-Gook
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.6 no.2
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    • pp.95-106
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    • 2007
  • This paper proposes an effective tempo feature extraction method for music information retrieval. The tempo information is modeled by the narrow-band temporal modulation components, which are decomposed into a modulation spectrum via joint frequency analysis. In implementation, the tempo feature is directly extracted from the modified discrete cosine transform coefficients, which is the output of partial MP3(MPEG 1 Layer 3) decoder. Then, different features are extracted from the amplitudes of modulation spectrum and applied to different music information retrieval tasks. The logarithmic scale modulation frequency coefficients are employed in automatic music emotion classification and music genre classification. The classification precision in both systems is improved significantly. The bit vectors derived from adaptive modulation spectrum is used in audio fingerprinting task That is proved to be able to achieve high robustness in this application. The experimental results in these tasks validate the effectiveness of the proposed tempo feature.

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A Study on Hydraulic Characteristics of Rock Joints Dependant on JRC Ranges (JRC 등급에 따른 절리면 수리특성 연구)

  • Chae Byung-Gon;Seo Yong-Seok;Kim Ji-Soo
    • The Journal of Engineering Geology
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    • v.14 no.4 s.41
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    • pp.461-468
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    • 2004
  • In order to characterize hydraulic property dependant on join roughness in rock mass, this study computed permeability coefficients on each range of joint roughness coefficient (JRC) suggested by Barton(1976). For a quantitative analysis of roughness components spectral analysis using the fast fourier transform was performed to select effective frequencies on each PC range. The results of spectral analyses show that low ranges of the JRC are mainly composed of low frequency domain, while high ranges of the JRC have dominant components at high frequency domain. The inverse Fourier transform made it possible to generate joint models of each JRC range using the effective frequencies of roughness spectrum. The homogenization analysis was applied to calculate permeability coefficient at homogeneous microscale, and then, computes a homogenized permeability coefficient (C-permeability coefficient) at macro scale. Therefore, it is possible to analyze accurate characteristics of permeability reflected with local effect of facture geometry. According to the calculation results, permeability coefficients were distributed between $10^{-3}m/sec\;and\;10^{-4}/sec$. In cases of sheared joint models permeability coefficients were plotted between $10^{-4}m/sec\;and\;10^{-5}/sec$, showing irregular distribution of permeability coefficients on each IRC range. The differences of permeability coefficients for the same aperture models or for the sheared joint models indicate that changes of roughness pattern influence on permeability coefficients. Therefore, the effect of joint roughness should be considered to characterize hydraulic properties in rock joints.

Development of Impact Factor Response Spectrum based on Frequency Response of Both Ends-Fixed Beam for Application to Continuous Bridges (연속교 적용을 위한 양단고정지지 보의 진동수 기반 충격계수 응답스펙트럼 개발)

  • Roh, Hwasung;Lee, Huseok;Park, Kyung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.12
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    • pp.301-306
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    • 2016
  • In bridge performance assessments, a new load carrying capacity evaluation model of simple bridges was proposed, which is based on the developed simple support impact factor spectrum. In this paper, a conservative assumption that the inner span with the both ends fixed boundary condition is ideal for applying the impact factor response spectrum for continuous bridges. The impact factor response spectrum has been proposed based on this assumption. The response spectrum by comparing the numerical analysis result and actual measurement data verified the applicability. The analysis was loading the moving load of DB-24 in a six-span continuous bridge, which was the same as the actual measurement data, the dynamic response was measured in the fourth span. The frequency of the bridge was obtained by FFT on the acceleration response and the span-frequency of sample bridge was calculated by the frequency. The impact factor of the sample bridge was determined by applying the span-frequency of the bridge to the proposed response spectrum; it was similar to the result of comparing the actual measured impact factor. Therefore, the method using the impact factor response spectrum based on the frequency response of both ends-fixed beam was found to be applicable to an actual continuous bridge.

Effect of Prefrontal Neurofeedback Training on the Attention and Sleep of Adolescent (전전두엽 뉴로피드백 훈련이 청소년의 주의력과 수면에 미치는 영향)

  • Shin, Ji-Eun;Kim, Yong-Gi;Weon, Hee-Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.3
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    • pp.447-452
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    • 2020
  • The purpose of this research was to confirm that prefrontal neurofeedback training has an impact on adolescents. The objective of this study was to prove its scientific effect through experimentation. The effect of the training was measured by the difference in neuro?frequencies before and after the training. For this research, an experimental group and a control group, each with 22 students in J High School located in the city of S participated in this study. From May to July 2019, the training was conducted three times a week and for 30 minutes per session. The neuro?frequency data collected were analyzed through the methods of F.F.T. The resulting changes from the neurofeedback training for each group were analyzed by T-Tests. The result of the study is as follows; Neurofeedback training has had a positive effect on adolescent attention and sleep. In conclusion, the environmental and educational factors also play an important role. As the interaction of the latter two factors yield an individual's unique brain structure and functionality, the impact of the neurofeedback training is important on adolescents. The derivation of the above results by utilizing scientific and objective methods reemphasizes the importance of this study.

Correlation between Visual Sensibility and Vital Signal using Wearable based Electrocardiogram Sensing Clothes (웨어러블 기반의 심전도 측정 의복을 이용한 시각감성과 생체신호간의 상관관계)

  • Chung, Kyung-Yong
    • The Journal of the Korea Contents Association
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    • v.9 no.12
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    • pp.496-503
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    • 2009
  • In the life environment changed with not only the material abundance but also the quality, it is the most crucial factor for the strategy of sensibility engineering to investigate vital signal according to the sensibility. In this perspective, it is necessary to design and merchandise the products in cope with each sensibility and needs as well as its functional aspects. In this paper, we proposed the correlation between the visual sensibility and the vital signal using the wearable based electrocardiogram sensing clothes. We measured the electrocardiogram (ECG) signal by wearing the electrocardiogram sensing clothes. The heart rate variability (HRV) is calculated form the acquired ECG signal by wearing the electrocardiogram sensing clothes. And the power spectrum analysis using the Fast Fourier Transform (FFT) is evaluated the correlation between the visual sensibility and the vital signal. we plan to conduct empirical applications to verify the adequacy and the validity of the proposed method.

Image Fusion of High Resolution SAR and Optical Image Using High Frequency Information (고해상도 SAR와 광학영상의 고주파 정보를 이용한 다중센서 융합)

  • Byun, Young-Gi;Chae, Tae-Byeong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.1
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    • pp.75-86
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    • 2012
  • Synthetic Aperture Radar(SAR) imaging system is independent of solar illumination and weather conditions; however, SAR image is difficult to interpret as compared with optical images. It has been increased interest in multi-sensor fusion technique which can improve the interpretability of $SAR^{\circ\circ}$ images by fusing the spectral information from multispectral(MS) image. In this paper, a multi-sensor fusion method based on high-frequency extraction process using Fast Fourier Transform(FFT) and outlier elimination process is proposed, which maintain the spectral content of the original MS image while retaining the spatial detail of the high-resolution SAR image. We used TerraSAR-X which is constructed on the same X-band SAR system as KOMPSAT-5 and KOMPSAT-2 MS image as the test data set to evaluate the proposed method. In order to evaluate the efficiency of the proposed method, the fusion result was compared visually and quantitatively with the result obtained using existing fusion algorithms. The evaluation results showed that the proposed image fusion method achieved successful results in the fusion of SAR and MS image compared with the existing fusion algorithms.

Vital Signal Monitoring Simulation System by Various Visual Stimulus (다양한 시각자극에 따른 생체신호 모니터링 시뮬레이션 시스템)

  • Chung, Kyung-Yong
    • The Journal of the Korea Contents Association
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    • v.11 no.1
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    • pp.1-8
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    • 2011
  • With the development of next IT convergence technology and the construction of infrastructure for personalized services, the importance of services based on user's sensibility status and vital signal is being spotlighted. It is the most crucial factor for the strategy of sensibility engineering to investigate student's vital signal according to the sensibility. In this paper, we proposed the vital signal monitoring simulation system by the various visual stimulus. The proposed method obtained the student's vital signal by the various visual stimulus. And the power spectrum analysis using the fast fourier transform is evaluated the activity level between the sympathetic and the parasympathetic. The analyzed result is monitoring the sensibility by displaying the heath signal light. To evaluate the sensibility between the high school's students and the university's students, we conducted SD profile and paired T-tests so as to verify usefulness. This evaluation found that the difference of sensibility activity by positive and negative stimulus was statistically meaningful. Ultimately, this paper suggests empirical application to verify the adequacy and the validity.