• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.9-16
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• 2003

In this paper, we propose an ATM processor suitable for VoDSL subscriber's equipments. The processor is composed of ATM block, AAL protocol block and ATS scheduler, and provides up to 4 VCC which service data and voice traffics on the ATM network. The proposed ATS scheduler can guarantee QoS of the voice traffic and supports multiple AAL2 packet. The ATM processor is manufactured on the 0.35 micron fabrication line of HYNIX semiconductor and provides the maximum data transfer rate of up to 52 Mbps. We implement the LAD, which is the VoDSL subscriber's equipment. The experimental results on the test bed network shows that the proposed hardware scheme successfully services most of the applications of the VoDSL services.

• Journal of Convergence Society for SMB
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• v.4 no.1
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• pp.1-6
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• 2014

PB/MC-CDMA is an efficient system which divides the whole frequency band into several blocks, unlike a conventional MC-CDMA system. We propose an efficient resource allocation scheme in Multi-Block PB/MC-CDMA (Partial Block Multi-Carrier Code Division Multiple Access). This system aims to improve frequency efficiency and maximize the total throughput while satisfying predefined threshold over various channel conditions. Through computer simulations, we confirm that the performance of the proposed system is more effective in terms of throughput.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.915-929
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• 2008

In this paper, we propose an algorithm for pixel-based disparity estimation with reliability in the multi-view image. The proposed method estimates an initial disparity map using edge information of an image, and the initial disparity map is used for reducing the search range to estimate the disparity efficiently. Furthermore, disparity-mismatch on object boundaries and textureless-regions get reduced by adaptive block size. We generated intermediate-view images to evaluate the estimated disparity. Test results show that the proposed algorithm obtained $0.1{\sim}1.2dB$ enhanced PSNR(peak signal to noise ratio) compared to conventional block-based and pixel-based disparity estimation methods.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.1
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• pp.102-107
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• 2000

In general text compression techniques cannot be used directly in image compression because the model of text and image are different Recently, a new class of text compression, namely, block-sorting algorithm which involves Burrows and Wheeler transformation(BWT) gives excellent results in text compression. However, if we apply it directly into image compression, the result is poor. So, we propose simple method in order to improve the lossless compression performance of image. The proposed method can be divided into three steps. It is decomposed into ten subbands with the help of symmetric short kernel filter. The resulting subbands are block-sorted according to the method by BWT, and the redundancy is removed with the help of an adaptive arithmetic coder. Experimental results show that the proposed method is better than lossless JPEG and LZ-based compression method(PKZIP).

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1402-1411
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• 2014

Buyer-seller watermarking protocol is defined as the practice of imperceptible altering a digital content to embed a message using watermarking in the encryption domain. This protocol is acknowledged as one kind of copyright protection techniques in electronic commerce. Buyer-seller watermarking protocol is fundamentally based on public-key cryptosystem that is operating using the algebraic property of an integer. However, in general usage, digital contents which are handled in watermarking scheme mostly exist as real numbers in frequency domain through DCT, DFT, DWT, etc. Therefore, in order to use the watermarking scheme in a cryptographic protocol, digital contents that exist as real number must be transformed into integer type through preprocessing beforehand. In this paper, we presented a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework and homomorphic encryption method for buyer-seller watermarking protocol. We applied integral-processing in order to modify the decimal layer. And we designed a direction-adaptive watermarking scheme by analyzing distribution property of the frequency coefficients in a block using JND threshold. From the experimental results, the proposed scheme was confirmed to have a good robustness and invisibility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1587-1594
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• 1994

The pitch predictor is one of the most important part for the robust tree coder. The hybrid backward pitch adapation which is a combination of a block adaptation and a recursive adaptation is used for the pitch predictor. In order to improve the error performance and track the pitch period change of the input speech, it is proposed to smooth the input of the pitch predictor. The smoother with three taps can have fixed coefficients or variable coefficients depending on the estimated autocorrelation function of the output of the pitch synthesizer. The inclusion of a variable smoother can track the pitch period change within a block and reduce the effect of channel errors.

• Communications for Statistical Applications and Methods
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• v.19 no.2
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• pp.225-235
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• 2012

Noise reduction is an important issue in the field of image processing because image noise worsens the quality of the input image. The basic difficulty is that the noise and the signal are not easy to distinguish. Simple moothing is one of the most basic and important procedures to remove the noise, however, it does not consider the level of noise. This method effectively reduces the noise but the feature area is simultaneously blurred. This paper considers the block approach to detect noise and image features of the input image so that noise reduction could be adaptively applied. Simulation results show that the proposed algorithm improves the overall quality of the image by removing the noise according to the noise level.

• The Journal of Korean Association of Computer Education
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• v.9 no.2
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• pp.101-109
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• 2006

We propose an adaptive digital watermarking algorithm using HVS(human visual system) and SOM(Self-Organizing Map) among neural networks. This method adjusts adaptively the strength of the watermark which is embedded in different blocks according to block classification in DCT(Discrete Cosine Transform) domain. All blocks in 3 classes out of 4 are selected to embed a watermark. Watermark sequences are embedded in 6 lowest frequency coefficients of each block except the DC component. The experimental results are excellent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.549-556
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• 2000

In this paper, we propose a new adaptive stereo object tracking system that can be used when the back ground image is complex and the cameras are not fixed . In this method, we used the Block Matching Algorithm to separate the tracking object form the background image and then the optical JTC system is used to obtain the convergence-controlling and pa/tilt-controlling values fro the left and right cameras. the experimental results are found to track the object robustly & adaptively for the object tracking in various background images, and the possibility of real-time implementation of the proposed system by using the optical JTC is also suggested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1469-1482
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• 1993

A new image coding technique has been proposed based on the wavelet transform. To achieve lower ceding rates and good qualities in reconstructed images, some of wavelet coefficients were removed by thresholding and quantized in accordance with the sensitivity of the human visual system(HVS). For each block of subimages in wavelet transform domain, block thresholding scheme has been used to remove the unimportant wavelet coefficients according to the frequency characteristic and statistical property of wavelet coefficients. The location information of quantized blocks and removed blocks were encoded using run-length coder which is effective for the exponential distribution. Quantized coefficients were encoded using variable length coder which matches well to their distribution. Simulation results show that the reconstructed images maintain high quality with the low bit rate, below 1.0 bits per pel.