• Journal of Internet of Things and Convergence
• /
• v.8 no.2
• /
• pp.79-84
• /
• 2022

This paper presents an enhancement method of document restoration capability which is robust for security, loss, and contamination, It is based on two methods, that is, encryption and DnCNN(DeNoise Convolution Neural Network). In order to implement this encryption method, a mathematical model is applied as a spatial frequency transfer function used in optics of 2D image information. Then a method is proposed with optical interference patterns as encryption using spatial frequency transfer functions and using mathematical variables of spatial frequency transfer functions as ciphers. In addition, by applying the DnCNN method which is bsed on deep learning technique, the restoration capability is enhanced by removing noise. With an experimental evaluation, with 65% information loss, by applying Pre-Training DnCNN Deep Learning, the peak signal-to-noise ratio (PSNR) shows 11% or more superior in compared to that of the spatial frequency transfer function only. In addition, it is confirmed that the characteristic of CC(Correlation Coefficient) is enhanced by 16% or more.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2570-2575
• /
• 2003

Monitoring a power transmission line is significant for power electric companies. In this paper, we propose a new method for detecting an fault point of power transmission line by use of M-sequence correlation technique. In this method, detecting signal is used as one or plural M-sequences ( same characteristic polynomial, including normal and reverse mark, synchronized ). In receiving point, we make same sequence with the input one and take crosscorrelation function between M-sequence and the received signal. We can see transfer fanctions of plural paths between inputs and a output taps separated from different of delay times on the crosscorrelation function, and from these transfer fanctions, so we compare them when fault occurred with in usual.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.77-80
• /
• 2001

In this paper, it is analyzed the statistical characteristics on the transmission performance of the optical SCM transmission in the CDMA RF signal relay system. Using Mach-Zehnder modulator, optical signal is regenerated into CDMA RF signal. Transfer function model of mach-Zehnder modulator is approximated to the third power of the input signal using Taylor series. BER results are analyzed under the multiple access interference and multi-path fading environment.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.12
• /
• pp.1260-1268
• /
• 2009

Three methods(the stepped sine method, the statistical method(random excitation method) and the maximum-length sequence(MLS) method) for head-related transfer functions(HRTFs) are experimentally compared in view point of accuracy and efficiency. First, the stepped sine method has high signal-to-noise ratio, but low efficiency. Second, the statistical method is fast measurement speed, but weak to noise than the other methods. Finally, the MLS method shows both good efficiency and high signal-to-noise ratio, but it needs additional software or equipment such as MLS signal generator. For comparison of measurement accuracy, HRTFs of KEMAR dummy are measured for various azimuths and elevations. Error norms for magnitude and phase of HRTFs are defined and calculated for the measured HRTFs. The calculated error norms show that the methods give similar results in magnitude and phase except a little phase difference in the MLS method.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.8
• /
• pp.741-746
• /
• 2007

In this study, transfer path identification and output estimation are simulated by multi-dimension spectral analysis method (MDSA). Multi -input/single-output system give expression the vehicle suspension which each inputs are correlated reciprocally. In case of correlating with inputs, the system needs separating the each input signal by MDSA. Main simulations are about finding effective input by coherent output spectrum and selecting optimal input's number by multiple coherence function. Also, by shielding transfer path of each input, transfer path characteristic is identified in terms of overall integrated contribution level.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.404-406
• /
• 2002

We have investigated the contribution of the scattered x rays to the signal imaging in the radiographs acquired with anti-scatter grids of several grid ratios by separating the line spread functions (LSFs) derived from the signal edge image into the primary and the scatter components. By using a 1.0-mm lead plate in the scattering material, the blurred signal edge images were acquired by use of an imaging plate at a tube voltage of 80 kV with the anti-scatter grids of grid ratios for 5:1, 6:1, 8:1, 10:1 and 12:1. The edge profiles of the signal images were scanned and those in relative exposure were differentiated to obtain the LSFs. To investigate the contribution of the scattered x rays to the signal imaging, we proposed a method for separating the LSFs derived from the signal images into the primary and the scatter components, where the scatter component was approximated with exponential function. Our basic approach is to separate the area of the LSFs by ratios of the scattered x-ray exposure to the primary x-ray exposure, which were obtained for the grid ratios by use of a lead disk method. The LSFs and the two components were Fourier transformed to obtain the modulation transfer functions (MTFs) and their two components. As the result, we found that, by using the anti-scatter grids, the scattered x rays were reduced, but the shape of the LSFs of the scatter component hardly changed. The contributions of the scatter component to the MTFs were not negligible (more than 10 %) for spatial frequencies lower than about 1.0 mm$\^$-l/ and that was greater as the grid ratio decreasing. On the other hand, for higher frequencies, the primary component was dominant compared with the scatter component.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.9
• /
• pp.158-164
• /
• 1999

In this paper a simple measurement technique for mechanical-acoustic transfer functions is proposed . The mechanical-acoustic transfer functions, generally , are measured through mechanical excitations ; impact hammers or shakers. Recently , by virtue of vibro-acoustical reciprocity principle, they are measured through acoustic excitations : loudspeakers. This kind of test needs to measure the volume velocity , the radiation characteristics of a sound source. Because the volume velocity of the sound source is changed by driving signal , it is difficult to measure it. However , the new method in this paper needs not to measure the volume velocity of a sound source by combination of mechanical and acoustic excitations. Moreover, this method has the methodological advantages, such as usage of a general loudspeaker for the reciprocal excitation, no sptatial limitations for measurements of mechanical-acoustic transfer functions.

• Journal of Korea Multimedia Society
• /
• v.6 no.7
• /
• pp.1131-1138
• /
• 2003

Active noise control(ANC) is an approach to noise reduction in which a secondary noise source destructively interferes with the unwanted noise is introduced. Generally, the performance of ANC is determined how well a secondary noise tracks noises. A secondary noise is generated from the cancelling speaker and a error sensor pick up error signal. The transfer function between the cancelling speaker and the error sensor is not flat and distorts secondary noises. Consequently, the performance of ANC is degraded by the transfer function. In this paper, a single sensor ANC which considers the characteristics of the speaker and the error sensor is proposed. To reduce distortion of secondary noises, the transfer function is estimated by adaptive inverse modelling and the primary noises are estimated by Kalman filter. Experimental results show that the proposed single sensor ANC effectively attenuates noises.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1214-1221
• /
• 2005

In this paper, we propose a digital watermarking method for still images, in which the human visual system (HVS) is used in the discrete cosine transform (DCT) domain. The modulation transfer function (MTF) of the HVS model is employed to increase the invisibility of the inserted watermark in images. The proposed watermarking method is shown to be robust to several common image processing techniques, including lowpass filtering and cropping. Also, using the energy relationship of the DCT, we derive the equation that directly computes the watermark weighting factor in the DCT domain for the specified peak signal to noise ratio (PSNR) of the still image and the length of watermark to be inserted. The difference between desired PSNR and PSNR in spatial domain is within 0.07dB for the 7 test images.

• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.1
• /
• pp.56-61
• /
• 2011

Many control techniques have been proposed in order to improve the control performance of the control system. The degree of freedom on control in the control system is decided by the number of the closed-loop transfer function which can adjust independently. The controller design scheme with two degrees of freedom(TDOF) is extensively used for securing the good control performance to trace a desired value and reject disturbance. In this paper, PID controller is used by controller with TDOF and the design method for control system with TDOF is proposed by the normal method. Using the coefficients of the transfer function of the plant, the transfer function of the control system is normalized by the proposed design method and the parameters of the controller are determined. The control system with the TDOF is constructed by using this method. Through the simulation results, the usefulness of the proposed algorithm is proved.