• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.16-22
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• 2012

In this paper, the forensic marking algorithm is proposed using psychoacoustic model II and MDCT for high-quality audio. The proposed forensic marking method, that inserts the user fingerprinting code of the audio content into the selected sub-band, in which audio signal energy is lower than the spectrum masking level. In the range of the one frame which has 2,048 samples for FFT of original audio signal, the audio forensic marking is processed in 3 sub-bands. According to the average attack of the fingerprinting codes, one frame's SNR is measured on 100% trace ratio of the collusion codes. When the lower strength 0.1 of the inserted fingerprinting code, SNR is 38.44dB. And in case, the added strength 0.5 of white gaussian noise, SNR is 19.09dB. As a result, it confirms that the proposed audio forensic marking algorithm is maintained the marking robustness of the fingerprinting code and the audio high-quality.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.51-56
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• 2022

In this study an efficient method for detecting and monitoring engine misfiring, focusing on minute speed changes in the crankshaft is proposed., Its validity is verified using various misfiring cases. Typically, the crankshaft speed fluctuates around the normal value depending on the engine misfiring status. Even a minute speed change in the crankshaft can be estimated by measuring the rotation time of each tooth of the 118-tooth flywheel attached to the crankshaft with a 2-MHz timer. Therefore, a speed pattern for an in-line six-cylinder engine consists of 236 tooth rotation speeds corresponding to the two rotations of the crankshaft, in which all the cylinders complete four-stroke cycle. FFT analysis can reduce the number of components of a speed pattern from 236 to just four major components: - fundamental frequency_(f), 2f, 3f, 6f., - This makes the comparison of the misfiring cases simpler and faster. In the experiment, five engine status cases (one normal firing and, four misfiring cases) were simulated. While the 6f component was the largest for the normal case, the f component increased as misfiring occurred one, two apart, and two consecutive times. The 3D FFT pattern comprising the ratio of f, 2f, and 3f, 6f showed that the distance between the misfiring and normal states was larger

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.453-456
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• 2001

21세기에 새로운 분야로 대두되고 있는 가상현실은 많은 사람들의 흥미를 끌고 있다. 상상 속에서나 가능하던 일들을 현실감과 입체감을 통해 실제처럼 느낄 수 있게 해준다는 것이 가상현실의 가장 큰 매력일 것이다. 가상현실을 요하는 멀티미디어 기기들의 활발한 시장진출로 3D 효과를 가진 오디오/비디오의 하드웨어 구현이 불가피하다. 본 연구에서는 휴대용 기기들에서 실시간 3D 입체음향 효과를 얻을 수 있도록 하드웨어를 구성하였다. 기존의 입체음향 기술에서 사용되는 콘볼루션 방법은 계산량이 많기 때문에 실시간 구현이 어렵다. 그러나 제안된 방식은 FFT를 사용하여 주파수 영역에서 처리함으로써 계산량을 줄여 하나의 프로세서로도 실시간 처리가 가능하도록 하였다. 저가/저전력/소형화조건을 요구하는 휴대용 기기에서 3D 입체 음향 효과를 얻을 수 있는 것이다. DSP는 TI(Texas Instruments)사의 16비트 고정소수점(fixed-point) 프로세서인 TMS320C5416을 사용한다. 구현된 3D 입체음향 칩은 입체음향을 필요로 하는 휴대용 MP3 Player, 가전용 오디오/비디오 등에 응용될 수 있다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.67-74
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• 1997

In this paper, we psresent a new scheme to synthetically generate a HPO digital hologram for a three-dimensional image that is modelled as the horizontally stacked two-dimensional images. The proposed method transforms a lightwave field into the angular spectrum of planewaves, which enables this method to use FFT routines, rather than using numerous arithmetic calculations. Hence, this method may be able to not only lead to the dramatically less computation but provide relatively excellent performances due to the phase error-free transformation. We present sampling constraints and implementaton procedure to obtian a hololine for each image and also point out the necessity of interpolation. Simulatioj results are presented to show the comparison with the conventional method in terms of computation time and performances, including the behaviors resulting form the different selection of parameter values to be used in the interpolations.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.75-75
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• 2002

목적： 고자장 자기공명영상 시스템 등으로 신호대잡음비가 향상됨에 따라 데이터 측정에서 analog-to-digital converter (ADC)의 quantization noise 가 중요한 시스템 사양으로 부각되고 있다. 특히 자기공명영상은 공간주파수 영역에서 데이터를 측정하기 때문에 dc와 ac간의 신호 차이가 매우 크며, 이러한 dynmic range는 3-D 영상에서 더욱 커진다. 본 연구에서는 다양한 자기총명 영상기법 및 실험 파라미터에 따른 신호의 dynamic range와 ADC의 bit 수에 따른 quantization noise를 살펴봄으로써, 주어진 시스템에 적합한 ADC의 bit 수를 분석하고자 한다. 대상 및 방법： 펄스 시퀀스의 종류, 파라미터, 2D/3D 등에 따른 각 신호의 크기를 수학적으로 모델링하여 신호의 크기를 예측하였다. 또한 whole body MRI 시스템에서 실험을 통하여 신호의 크기를 비교하였다. ADC의 quantization noise를 실험과 시뮬레이션을 통하여 살펴보았다. 시뮬레이션은 test 영상을 Inverse FFT 하여 spatial frequency domain data를 만든 후, 다양한 bit 수의 ADC로 quantization을 한 후 다시 영상을 재구성하였다. 재구성된 영상과 원영상 간의 error가 quantization noise가 된다. 또한 이러한 error가 주파수 영역에서의 error 값과 일치하는지를 확인하였다.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.33-43
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• 2007

In this proper, we proposes a robust watermarking against the lossy compression in the Hadamard domain. The Hadamard matrix consists of only 1 or -1 and can be computed veru fast. The Hadamrd transform has the inverse transform therefore it is able to be applied into the watermarking technology. In embedding process, we select 10 coefficients from intermediate frequency domain and create two watermark patterns. In extraction process, we use the watermark patterns and compare them to detect the watermark information. When we use the standard image ($512{\times}512$) and binary watermark image ($64{\times}64$), the results of these examines are PSNR for $38{\sim}42dB$ and BER for $3.9{\sim}12.5%$. The JPEG QF between 30 and100, naked human eyes can detect to watermark image easily. The experimental results show that performance of Hadamard domain is better than those of DCT, FFT, and DWT.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.145-148
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• 2001

This paper presents a phase-based stereo matching algorithm in order to efficiently extract 3-dimensional objects from two 2D images. Conventional phase-based methods, especially using windowed Fourier phases, inherit good properties in the cage of hierarchical approaches, because they basically use a multi-resolution phase map. On the contrary, their computational cost is too heavy. Therefore, a fast hierarchical approach, using multi-resolution phase-based strategy and reducing redundancies of phase calculations based on FFT concept is proposed in this paper. In addition, a structural matching algorithm on the phase domain is presented to improve the matching quality. In experimental results. it is shown that the computation loads are considerably reduced about 8 times and stable outputs are obtained from various images.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.294-296
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• 2018

최근 디지털 홀로그래피는 3차원 영상을 획득, 처리 및 재생을 하지만, 디스플레이 전자 소자 특성에 의한 시야각이 작아서 사용자의 관찰 가능한 시역이 제한적인 단점이 있으며, 따라서 복원된 입체 영상과 사용자 사이에 상호작용 서비스 제공이 용이하지 않는 한계를 지니고 있다. 본 논문에서 우리는 $360^{\circ}$ 전방향 (1,024 시점)의 홀로그래픽 3D 콘텐츠를 FFT 알고리즘을 이용하여 생성하고, 이 콘텐츠를 디스플레이할 수 있으면서 동시에 이 콘텐츠와 사용자 간 상호작용이 가능한, 광시야각 (${\pm}60^{\circ}$) 홀로그래픽 디스플레이 시스템의 설계 및 제작한 결과를 실증한다.

• Progress in Medical Physics
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• v.3 no.1
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• pp.71-78
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• 1992

This study describes the design of the biophysiological signal processing analyzer which can collect and analyze the biosignal raw data. System hardware is consisted of the IBM PC AT. pre-amplifier. AID converter, Counter/Timer. and RS-232C processor. Biophysiological signal data were processed by the software digital filter. FFT and graphic processing routine. The tachogram and FFT of the the peak to peak interval time was accomplished by the Graphic user interface software using the biophysiological signal processed data. Using this system. the powerspectrum of the heart rate variability during the long term could be observed. Experimental results of this system approach our purpose. which is improved the cost performance. easy to use. reducing raw-data noise and optimizing model for digital filter.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.359-362
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• 2012

The results are shown highly unstable mode's detonation dynamics by compared with weakly unstable mode. And we investigate the difference and similar features of 2D and 3D results. By using PSD via FFT, the effects of pre-exponential factor difference and of unstable mode were investigated in this study. The result of PSD is shown pulsed features in weakly unstable mode, but noselike in highly unstable mode. By compared between Sheliren image and overlaid slice image, the irregular feature of detonation waves structure was discussed in highly unstable mode.