• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.771-781
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• 1997

In order to solve the problem of uncovered background region due to the region-due to the region-based motion estimation, this paper presents a new method which generates the uncovered region memory using motion estimation and shows the application of the algorithm for very low bit rate video coding. The proposed algorithm can be briefly described as follows it detects the changed region by using the information of FD(frame difference) and segmentation, and then as for only that region the backward motion estimation without transmission of shape information is done. Therefore, from only motion information the uncovered background region memory is generated and updated. The contents stored in the uncovered background region memory are referred whenever the uncovered region comes into existence. The regions with large prediction error are transformed and coded by using DCT. As results of simulation, the proposed algorithm shows the superior improvement in the subjective and objective image quality due to the remarkable reduction of transmission bits for prediction error.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.863-866
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• 1998

In this paper, we proposes Moving Picture Compression reducing bit numbers within the block by probability in 3D-DCT considered of temporal axis. From Delta Modification theory for frequency components, bit numbers within the block(4$\times$4) were properly compressed by using the Probability Entropy. At the result for the proposed algorithm, we could find that the values of PSNR for resolution and the compression rate were better than existing methods.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.625-632
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• 2004

Since the H.264 encoding adopts both forward prediction and hi-direction prediction modes and exploits Variable Length Coding(VLC), the amount of data generated from video encoder varies as Flaying time goes by. The fixed bit rate encoding system which has limited transmission channel capacity uses a buffer to control output bitstream It's necessary to control the bitstream to maintain within manageable range so as to protect buffer from overflow or underflow. With existing bit amount control algorithms, the $\lambda_{MODE}$ which is relationship between distortion value and quantization parameter often excesses normal value to end up with video error. This paper proposes an algorithm to protect buffer from overflow or underflow by introducing a new quantization parameter against distortion value of H.264 video data. The test results of 6 exemplary data show that the proposed algorithm has the same PSNR as and up to 8% reduced bit rate against existing algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.535-540
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• 2005

This paper presents a scalable caching algorithm of proxy server with the finite storage size minimizing client's buffer size and constant-bit-rate channel bandwidth. Under the general video traffic condition, it is observed that the amount of decreased client's buffer size and channel bandwidth after caching a video frame depends on the relative frame position in the time axis as the frame size. Based on this fact, we propose an effective caching algorithm to select the cached frames by using the normalized buffer size. Finally, experimental results are provided to show the superior performance of the proposed alghrithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.55-60
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• 2021

This paper relates with the performance evaluation of QE-MMA (Quantized Error-MMA) adaptive equalization algorithm based on the stepsize and quantizer bit number in order to reduce the intersymbol interference due to nonlinear distortion occurred in the time dispersive channel. The QE-MMA was proposed using the power-of-two arithmetic for the H/W implementation easiness substitutes the multiplication and addition into the shift and addition in the tap coefficient updates process that modifies the SE-MMA which use the high-order statistics of transmitted signal and sign of error signal. But it has different adaptive equalization performance by the step size and quantizer bit number for obtain the sign of error in the generation of error signal in QE-MMA, and it was confirmed by computer simulation. As a simulation, it was confirmed that the convergence speed for reaching steady state depend on stepsize and the residual quantities after steady state depend on the quantizer bit number in the QE-MMA adaptive equalization algorithm performance.

• Journal of Biomedical Engineering Research
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• v.6 no.2
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• pp.15-22
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• 1985

We have developed a microprogramir!able signal processor for real-time ultrasonic signal processing. Processing speed was increased by the parallelism in horizontal microprogram using 104bits microcode and the Pipelined architecture. Control unit of the signal processor was designed by microprogrammed architec- ture and writable control store (WCS) which was interfaced with host computer, APPLE- ll . This enables the processor to develop and simulate various digital signal processing algorithms. The performance of the processor was evaluated by the Fast Fourier Transform (FFT) program. The execution time to perform 16 bit 1024 points complex FF7, radix-2 DIT algorithm, was about 175 msec with IMHz master Clock. We can use this processor to Bevelop more efficient signal processing algorithms on the biological signal processing.

• Journal of Communications and Networks
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• v.15 no.1
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• pp.25-30
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• 2013

Uplink multicarrier code-division multiple-access (MC-CDMA) with equal gain combining (EGC) over Nakagami fading channels is considered. An improved expression which is a feasible alternative for the bit error rate (BER) performance evaluation of MC-CDMA signals is proposed. Simulated annealing algorithm is employed to obtain the optimum value of the coefficients belonging to the proposed expression. Numerical examples show that the performance curves computed by the improved expression are in good agreement with the results obtained by the exact expression. Thus, the proposed expression can improve the accuracy of BER performance evaluation that has been realized by the approximate expression.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.355-361
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• 2009

This paper proposes a new basic unit level rate control algorithm which generates the output bits corresponding to the target bits. The H.264 standard uses various coding modes and optimization methods to improve the compression performance, which makes it difficult to control the generated traffic accurately. In the proposed scheme, the allocated bits to a frame are distributed to all basic units properly to encode each basic unit according to the bit budget. After encoding the frame, the encoding parameters are adjusted according to the difference between the target and the resulting values. It is shown by experimental results that the new algorithm can generate output bit rates accurately corresponding to the target bit rates with the PSNR performance better than that of the existing rate control algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.4
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• pp.195-205
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• 2014

The ultra-high definition television (UHDTV) has been considered as a next generation broadcsating service. However the conventional digital terrestrial transmission system cannot afford the required transmission data rate of UHDTV, and thus adopting ultra-high order constellation, such as 4096-QAM, into the conventional DTT systems has been studied. In particular, when the ultra-high order constellation is adopted into the digital video broadcasting-2nd generation terrestrial (DVB-T2) unequal-error protection (UEP) properties of a codeword of an error correction coding and ultra-high order constellations should be properly matched by bit mapper in order to enhance the decoding performance. Because long codeword results in a heavy computational complexity to design the bit mapper, the DVB-T2 divided it into cascaded blocks, the bit interleaver and the bit-to-cell DEMUX, and there have been many researches related to each block. However, there are few published study related to design methodology of bit interleaver. In this respect, this paper proposes a design methodology of the bit interleaver and presents bit interleavers of 1024-QAM and 4096-QAM according to the proposed design algorithm. The newly designed interleavers improved the decoding performance of the error correction coding by maximally 0.6 dB SNR over both of AWGN and random fading channel.

• Journal of Information Processing Systems
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• v.13 no.1
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• pp.114-127
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• 2017

This paper proposes a color image coding algorithm based on shape-adaptive all phase biorthogonal transform (SA-APBT). This algorithm is implemented through four procedures: color space conversion, image segmentation, shape coding, and texture coding. Region-of-interest (ROI) and background area are obtained by image segmentation. Shape coding uses chain code. The texture coding of the ROI is prior to the background area. SA-APBT and uniform quantization are adopted in texture coding. Compared with the color image coding algorithm based on shape-adaptive discrete cosine transform (SA-DCT) at the same bit rates, experimental results on test color images reveal that the objective quality and subjective effects of the reconstructed images using the proposed algorithm are better, especially at low bit rates. Moreover, the complexity of the proposed algorithm is reduced because of uniform quantization.