• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1163-1170
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• 2013

Digital watermarking techniques have been used as one of the means for copyright protection and authentication of multimedia data. Conventional Chinese Remainder Theorem(CRT)-based spatial domain watermarking techniques do not perform well under JPEG compression. However, it is seen that the CRT-based watermarking technique in Discrete Cosine Transform(DCT) domain performs well for JPEG compression. In this paper, an improved CRT-based image watermarking method in the DCT domain is proposed. The proposed method provides better robustness which decreases changes of absolute difference of residues against rounding errors due to DCT conversion and various attacks. Experimental results show that the proposed method has a good robustness against various attacks compared with the conventional CRT-based watermarking in DCT domain.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.95-101
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• 2011

In this paper, we propose the gaussian mixture model based pattern classification algorithm of forearm electromyogram. We define the motion of 1-degree of freedom as holding and unfolding hand considering a daily life for patient with prosthetic hand. For the extraction of precise features from the EMG signals, we use the difference absolute mean value(DAMV) and the mean absolute value(MAV) to consider amplitude characteristic of EMG signals. We also propose the D_DAMV and D_MAV in order to classify the amplitude characteristic of EMG signals more precisely. In this paper, we implemented a test targeting four adult male and identified the accuracy of EMG pattern classification of two motions which are holding and unfolding hand.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.264-273
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• 2002

Adaptive filters cannot exactly estimate the echo path of the receiving room because of the cross-correlation of stereo signals. In this paper, a new pre-processing method reducing the cross-correlation without degradation of stereophony is proposed to enhance the performance of stereophonic acoustic echo canceller. To reduce the cross-correlation, absolutes of two orthogonal signals derived from each channel signals are added to original channel signals. Assuming that the power of each channel signal is larger than that of the cross-correlation, the computation of pre-processing can be reduced. As results of simulations, it is shown that the performance of stereo acoustic echo canceller with the proposed pre-processing method is better than that of conventional ones.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.3
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• pp.357-364
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• 2015

This research presents a DC-DC converter controller implemented with an analog memory. The structure of the converter will contribute to solve the stability problem unavoidable in a conventional closed loop converter. The analog memory will be used for realizing CAM(Contents Addressable Memory) which contains the output of the converter and the relevant duty ratio, respectively. The operation for reading in the memory is executed with an absolute differencing circuit and a WTA(Winner-Take-All) circuit suitable for a nearest-match function of the CAM. We also present a system architecture that enables highly-paralleled fast writing and quick readout as well as high integration density.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.370-375
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• 2018

In this study, we have applied fractional precipitation with hydrophilic polymer in order to decrease the particle size of the (+)-dihydromyricetin from plant materials. When compared with the case where no hydrophilic polymer was employed, the addition of hydrophilic polymer in fractional precipitation resulted in a considerable decrease in the size of the (+)-dihydromyricetin precipitate. Among the polymers used, HPMC 2910 was the most effective for inhibition of precipitate growth. A polymer concentration of 0.1% (w/v) yielded the smallest particle size. The particle size was reduced by ~40% compared to control. In addition, the precipitate size was inversely correlated with the absolute value of the zeta potential of the suspension with polymer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.384-389
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• 2003

A new two-step soft-output Viterbi algorithm (SOVA) decoder architecture is presented. A significant reduction in the decoding latency can be achieved through the use of the dual-port RAM in the survivor memory structure of the trace-back unit. The system complexity can be lowered due to the determination of the absolute value of the path metric differences inside the add-compare-select (ACS) unit. The proposed SOVA architecture was verified successfully by the functional simulation of Verilog HDL modeling and the FPGA prototyping. The SOVA decoder achieves a data rate very close to that of the conventional Viterbi Algorithm (VA) decoder and the resource consumption of the realized SOVA decoder is only one and a half times larger than that of the conventional VA decoder.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6A
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• pp.517-523
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• 2002

The closed from of sums and weighted sums of the score functions of the locally optimum rank detectors are obtained in this paper. When we consider the asymptotic performance characteristics of a detector based on rank and sign statistics, the sums and weighted sums of the score functions have to be prepared. The efficacy of a detector can be obtained from the sums and weighted sums of the score functions. Score functions based on rank statistics, as well as those based on magnitude rank and sign statistics, have also been considered, which includes most score functions presented in the literature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.543-552
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• 1994

Dynamic Time Warp(DTW) needs for iterative calculations and the design of PE cell suitable for the operations is very important. Accordingly, this paper aims at real time recognition design enables large dictionary hardware realization using DTW algorithm. The DTW PE cell separated into three large blocks. "MIN" is the one block for counting accumulated minimum distance. "ADD" block calculates these minimum distances, and "ABS" seeks for the absolute values to the total sum of local distances. Circuit design and verification about the three block have been accomplished, and performed layout '||'&'||' DRC(design rule check) using 1.2 m CMOS N-Well rule base.CMOS N-Well rule base.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.127-131
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• 2005

We examined the effect of low temperature heat-treatment on the optical properties of the photonic crystals self-assembled using a monodispersed spherical $SiO_2$ nanoparticle. When the heat treatment temperature increased, the reflectance peak, which is induced by the photonic band gap, moved to a shorter wavelength direction, and the peak intensity of Fabry-Perot fringes also increased. The highest reflectance peak intensity was obtained in the sample heat-treated at $250\~300^{\circ}C$. The heat-treatment reduced the average particle size and the quantity of defects, and increased the packing density of the photonic crystal.

• Journal of Korea Multimedia Society
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• v.8 no.8
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• pp.1051-1056
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• 2005

Least mean square(LMS) algorithm is one of the most popular algorithm in adaptive signal processing because of the simplicity and the small computation. But the convergence speed of time domain adaptive algorithm is slow when the spread width of eigen values is wide. Moreover we have to choose the step size well for convergency in this paper, we use adaptive algorithm of wavelet transform. And we propose a new wavelet based adaptive algorithm of wavelet transform. And we propose a new wavelet based adaptive algorithm with variable step size, which Is linear to absolute value of error signal. We applied this algorithm to adaptive noise canceler. Simulation results are presented to compare the performance of the proposed algorithm with the usual algorithms.