• Journal of the Korean Institute of Navigation
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• v.22 no.4
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• pp.59-67
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• 1998

A quick and automatic detection with no harm to the goods is very important task for improving quality control, process control and labour reduction. In real fields of industry, defect detection is mostly accomplished by skillful workers. A narrow band eliminating spatial filter having characteristics of removing the specified spatial frequency is developed by the author, and it is proved that the filter has an excellent ability for on-line and real time detection of surface defect. By the way,. this spatial filter shows a ripple phenominum in filtering characteristics. So, it is necessary to remove the ripple component for the improvement of filter gain, moreover efficiency of defect detection. The spatial filtering method has a remarkable feature which means that it is able to set up weighting function for its own sake, and which can to obtain the best signal relating to the purpose of the measurement. Hence, having an eye on such feature, theoretical analysis is carried out at first for optimal design of narrow band eliminating spatial filter, and secondly, on the basis of above results spatial filter is manufactured, and finally advanced effectiveness of spatial filter is evaluated experimentally.

• Journal of information and communication convergence engineering
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• v.1 no.4
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• pp.189-193
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• 2003

A new algorithm is presented for adaptive notch filtering of narrow band or sine signals for embedded among broad band noise. The notch filter is implemented as a constrained infinite impulse response filter with a minimal number of parameters, Based on the recursive prediction error (RPE) method, the algorithm has the advantages of the fast convergence, accurate results and initial estimate of filter coefficient and its covariance is revealed. A convergence criterion is also developed. By using the information of the noise-to-signal power, the algorithm can self-adjust its initial filter coefficient estimate and its covariance to ensure convergence.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.1
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• pp.5-9
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• 2016

The modulation bandwidth of a reflective semiconductor optical amplifier (RSOA) is limited by carrier lifetime. Therefore, it is hard to directly modulate an RSOA with high-speed electrical signals. We theorize that an optical filter can act as an optical equalizer, compensating for the narrow bandwidth limitation imposed by the RSOA. By modeling a time-varying RSOA with a modified transfer matrix method (TMM), we simulated 25 Gbps operation of an RSOA with optical filtering effects. We investigated the impact of detuning the center wavelength of the optical filter on the modulation of an RSOA. The numerical results show that it is possible to modulate an RSOA with an optical filtering effect at 25 Gbps without electronic equalization or digital signal processing.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.582-589
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• 2016

Multi-mode monopulse system is widely used for satellite terminal like UAV because of high tracking accuracy and low size/weight profile. In order to calculate tracking error, Multi-mode monopulse system utilizes high-order mode signal, and it should have enough C/N(carrier to noise) level therefore tracking system needs narrow band filtering of received satellite beacon signal as much as possible. However, UAV suffers for beacon frequency drift derived from Doppler effect due to satellite figure 8 movement and UAV maneuvering. Therefore wideband signal processing needs to be considered in advance for exact doppler compensation and consequent time delay. In this paper, we propose the multi-stage Digital Signal processing system for beacon signal, which could minimize the signal delay under high Doppler and low C/N condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.648-661
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• 1997

This paper presents a new method for post-processing of coded images based upon the low-pass filtering followed by the projection onto the NQCS (narrow quantization constraint set). We also investigate how the proposed method works on JPEG-coded real images. The starting point of the QCS-based post-processing techniques is the centroid of the QCS, where the original image belongs. The low-pass filtering followed by the projection onto the QCS makes the images lie on the boundary of the QCS. It is likely that, however, the original image is inside the QCS. Hence projection onto the NQCS gives a lower MSE (mean square error) than does the projection onto the QCS. Simulation results show that setting the narrowing coefficients of the NQCS to be 0.2 yields the best performance in most cases. Even though the JPEG-coded image is low-pass filtered and projected onto the NQCS repeatedly, there is no guarantee that the resultant image has a lower MSE and goes closer to the original image. Thus only one iteration is sufficient for the post-processing of the coded images. This is interesting because the main drawback of the iterative post-processing techniques is the heavy computational burden. The single iteration method reduces the computational burden and gives us an easy way to implement the real time VLSI post-processor.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.419-426
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• 2008

Recently, localized heavy rain due to "EL-LIO" was a kind of reason by risk of slope stability. In this paper, the behaviour of slope when localized heavy rain was studied. In order to perform this study experimental programs were performed. Experimental programs was checked filtering conditions for slope stability due to localized heavy rain. And then, investigated slope stability and fracture mechanism each other types. In the experimental study, performed changing filtering condition by embankment, through five fixing factors such as rainfall intensity, slope shape, geological condition, compaction energy and water content. According to the results of this study, behaviour of facture slope has made a shallow and narrow waterway. This waterway expanded base stone. In order to, suggested a system for slope stability examination.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.439-446
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• 1995

In this paper, we present an algorithm for the detection of blood vessel contours in coronary aiteriograms. The proposed algorithm is based on both matched filtering and adaptive tracking. The proposed algorithm has merits in that it overcomes the bifurcation section problem as well as narrow vessel problem. Moreover, the algorithm has fast performance as well as insensitivity to noise.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.130-132
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• 2007

The characteristics of $S\breve{o}lc$ filters in $X^{(2)}$ nonlinear photonic crystals, periodically poled lithium niobate ($LiNbO_3$), were investigated by the Jones matrix method. The transmittance increases and the full width half maximum of the filter becomes narrow as the duty ratio increases. However, the filtering wavelength does not change. The transmittance at the filtering wavelength is over 95% when the duty ratio is larger than 0.35.

• Journal of the Korean Institute of Navigation
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• v.20 no.1
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• pp.81-85
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• 1996

The defects occurred in knitted fabrics have several types due to some trouble sources. In particular, the defects caused by knitting machine troubles give a serious damage to the whole webs. It is, therefore, necessary to discriminate the kind of defects. The method to discriminate the type and size of defects has been proposed, which is used a pair of narrow band eliminating spatial filters. This method is based upon an isotropic signal processing in time domain. This paper is to confirm that the proposed method can be useful in the discrimination of defects, having analyzed in spatial frequency domain.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.4
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• pp.29-34
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• 2002

In this paper, we present a new geometric active contour model based on level set methods introduced by Osher and Sethian for detection of object boundaries or shape and we adopt anisotropic diffusion filtering method for removing noise from original image. In order to minimize the processing time, we use the narrow band method which allows us to perform calculations in the neighborhood of the contour and not in the whole image. Using anisotropic diffusion filtering for each slice, we have the result with reduced noise and extracted exact shape. Volume rendering operates on three-dimensional data, processes it, and transforms it into a simple two-dimensional image.