• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.11
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• pp.20-28
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• 1997

In this paper, quantization and inverse quantizatio unit, a sa component of MPEG-2 moving picture compression system, ar edesigned. In the processing of quantization, this design adopted newly designed arithmetic units in which quantization matrices and scale code was expressed with SD(signed-digit) code. In the arithmetic unit of inverse quantization, quantization scale code, which has 5-bits length, is splited into two pieces; 2-bits for control code, 3-bits for quantization data, and the method to devise quantization step size is proposed. The design was coded with VHDL and synthesis results in that it consumed about 6,110 gates, and operating speed is 52MHz.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.31-40
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• 2016

In this paper, we propose a new anti-forensic method for hiding data in the timestamp of a file in the Windows NTFS filesystem. The main idea of the proposed method is to utilize the 16 least significant bits of the 64 bits in the timestamps. The 64-bit timestamp format represents a number of 100-nanosecond intervals, which are small enough to appear in less than a second, and are not commonly displayed with full precision in the Windows Explorer window or the file browsers of forensic tools. This allows them to be manipulated for other purposes. Every file has $STANDARD_INFORMATION and $FILE_NAME attributes, and each attribute has four timestamps respectively, so we can use 16 bytes to hide data. Without any changes in an original timestamp of "year-month-day hour:min:sec" format, we intentionally put manipulated data into the 16 least significant bits, making the existence of the hidden data in the timestamps difficult to uncover or detect. We demonstrated the applicability and feasibility of the proposed method with a test case.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.4
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• pp.97-105
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• 1994

Transform image coding using DCT is proved to be efficient in the absence of channel error but its performance degrades rapidly over noisy channel. In this paper, in the case of appling bit selcetive error correction coding that protects some significant bits in a codeword, an efficient allocation method of imformation bits and additive redundancy bits used for quantization and error correction coding respectively under constant transmission bit rate is proposed, and its performance is analyzed. As a result, without increasing trasmission bit rate, PSNR can be improved up to 7~8 [dB] below bit error rate $10^2$ and the image without blocking effect caused by bit error resulted from channel noise can be recostructed.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.41-51
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• 1997

In this study, two types of the direct digital frequency synthesizers (DDFS) designed and implemented using 1.0.mu.m CMOS gatearray(SOG) technolgoies are interoduced. To analize the effect of the number of phase bits(L), address data bits(A), and DAC bits (D) on the output spectrums of the DDFSs, the NCO-based BCD-DDFS composed of L=24, A=14, and D=8, and the improved binary-DDFS composed of L=24, A=8, and D=10 have been studied. The chips have been designed with and without a noise shapper to reduce spurious noises due to phase truncation and reduced sine ROM in output spectrum.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.3
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• pp.446-458
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• 2013

Recently, energy-efficient cellular transmission has received considerable research attention to improve the energy efficiency of wireless communication. In this paper, we consider a cellular network consisting of one base station (BS) and multiple user terminals and explore the network coding for enhancing the energy efficiency of cellular downlink transmission from BS to users. We propose the network coded cellular transmission scheme and conduct its energy consumption analysis with target outage probability and data rate requirements in Rayleigh fading environments. Then, the energy efficiency in Bits-per-Joule is further defined and analyzed to evaluate the number of bits delivered per Joule of energy cost. Numerical results show that the network coded cellular transmission significantly outperforms the traditional cellular transmission in terms of energy efficiency, implying that given a Joule of energy cost, the network coded cellular transmission scheme can deliver more bits than the traditional cellular transmission.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.2
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• pp.32-38
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• 1977

To organize the least control information for vector-drawing Korean characters, relatively simple 'Shortest Route Searching Algorithms' which can be applied to Korean character patterns were constructed. The shortest drawing routes and the common starting point for all charcters were found with this algorithm. It is shown that the vectors, which needs the least control informations to follow the shortest drawing route, are those vertical and horizontal vectors which have the size of 1 arid 3 times of raster distance. The vector control information for drawing 33 Korean characters including 9 double consonants and vowels can be organized with 7 bits 463 words of horizontal format informations which are corresponding to 3,241 bits.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.427-428
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• 2006

This paper presents an image fingerprinting scheme for the print-to-capture model performed by a photo printer and digital camera. When capturing an image by a digital camera, various kinds of distortions such as noise, geometrical distortions, and lens distortions are applied. slightly and simultaneously. In this paper, we consider several steps to extract fingerprints from the distorted image in print-and capture scenario. To embed ID into an image as a fingerprint, multi-bits embedding is applied. We embed 64 bits information as a fingerprint into spatial domain of color images. In order to restore a captured image from distortions a noise reduction filter is performed and a rectilinear tiling pattern is used as a template. To make the template, a multi-bits fingerprint is embedded repeatedly like a tiling pattern. We show that the extracting is successful from the image captured by a digital camera through the experiment.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.758-761
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• 2005

This paper describes the acoustic noise spectra of the pseudo-random carrier modulation technique according to the different PRBS(Pseudo Random Binary Sequence) bits. To confirm the validity of the proposed method, a 130v three-phase 5-level inverter motor drives was implemented. The harmonics spectra broadening effect of pseudo random carrier and the acoustic noise radiated from the inverter drives were discussed and verified according to the different bits of shift resister operating as PRBS.

• Journal of Semiconductor Engineering
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• v.1 no.1
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• pp.31-37
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• 2020

We present an approximate DRAM architecture for energy-efficient deep learning. Our key premise is that by bounding memory errors to non-critical information, we can significantly reduce DRAM refresh energy without compromising recognition accuracy of deep neural networks. To validate the key premise, we make extensive Monte-Carlo simulations for several well-known convolutional neural networks such as LeNet, ConvNet and AlexNet with the input of MINIST, CIFAR-10, and ImageNet, respectively. We assume that the highest-order 8-bits (in single precision) and 4-bits (in half precision) are protected from retention errors under the proposed architecture and then, randomly inject bit-errors to unprotected bits with various bit-error-rates. Here, recognition accuracies of the above convolutional neural networks are successfully maintained up to the 10^-5-order bit-error-rate. We simulate DRAM energy during inference of the above convolutional neural networks, where the proposed architecture shows the possibility of considerable energy saving up to 10 ~ 37.5% of total DRAM energy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1043-1053
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• 2012

In distributed video coding (DVC) systems, the complexity of encoders is greatly reduced by removing the motion estimation operations in encoders, since the correlation between frames is utilized in decoders. The transmission of parity bits is requested through the feedback channel, until the related errors are corrected to decode the Wyner-Ziv frames. The requirement to use the feedback channel limits the application of DVC systems. In this paper, we propose an efficient method to remove the feedback channel in DVC systems. First, a simple side information generation method is proposed to calculate the amount of parity bits in the encoder, and it is shown that the proposed method yields good performance with low complexity. Then, by calibrating the theoretical entropy with three parameters, we can calculate the amount of parity bits in the encoder and remove the feedback channel. Moreover, an adaptive method to determine quantization parameters for key frames is proposed. Extensive computer simulations show that the proposed method yields better performance than conventional methods.