• Journal of the Chungcheong Mathematical Society
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• v.19 no.4
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• pp.357-364
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• 2006

We study Hausdorff and packing dimensions of subsets of a general coding space with a generalized ultra metric from a multifractal spectrum induced by a self-similar measure on a self-similar Cantor set using a function satisfying a H${\ddot{o}}$older condition.

• Korean Journal of Mathematics
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• v.12 no.1
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• pp.1-5
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• 2004

We study Hausdorff and packing dimensions of subsets of a coding space with an ultra metric from a multifractal spectrum induced by a self-similar measure on a Cantor set using a function satisfying a H$\ddot{o}$lder condition.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.81-88
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• 2012

Space diversity and space multiplexing gain can be achieved with MIMO system. This paper proposes spatial coding method to MIMO system using data information and antenna selection technique. This technique provides coding gain as well as space diversity gain. For MIMO system with BPSK modulation, BER performance is analyzed and space diversity gains are compared through simulation in terms of data maldistribution degree.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.117-120
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• 2002

In this paper, we propose a new text watermarking method using space coding and PN sequence. A PN sequence generated from user message modifies the space between words in each line. The detection can be done without original text image using the average space with in the text. Experimental results show that proposed method has the invisible property and robustness to the attack such as the elimination of words in the text.

• Journal of Broadcast Engineering
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• v.20 no.5
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• pp.687-696
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• 2015

JCT-VC (Joint Collaborative Team on Video Coding) continues developing HEVC/Screen Content Coding (HEVC/SCC) as an extension for efficiently coding screen content videos, including computer animations, graphics, and electrical documents, based on HEVC/Range extension (HEVC/RExt.). Color space conversion from RGB space being captured from CCD sensors is popular in natural video coding. However, the conversion is often undesired for screen contents because of a significant loss in perceptual quality. Therefore, several coding tools including cross-component prediction (CCP) and in-loop adaptive color space transform (ACST) have been developed for an efficient screen content video coding in order to reduce the redundancies between color spaces while maintaining the original color space. In this paper, we review the two coding tools, i.e., CCP and ACST exploiting the correlation in the RGB color space and conduct the performance analysis of the coding tools. In our simulation results, CCP and ACST provide 11.7% BD-rate saving and 16.4% BD-rate saving, respectively, while the two coding tools provide 18.2% BD-rate saving in total. Following this idea, if the two coding tools are exclusively selected, we provide 93% encoding measurement time with a 0.3% coding loss.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.129-134
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• 2010

Rain attenuation can cause a serious problem that an availability of space communication link on Ka band becomes low. To reduce the effect of rain attenuation on the error performance of space communications in Ka band, an adaptive coding and modulation (ACM) scheme is required. In this paper, to achieve a reliable telemetry data transmission, we propose an adaptive coding and modulation level using turbo code recommended by the consultative committee for space data systems (CCSDS) and various modulation methods (QPSK, 8PSK, 4+12 APSK, and 4+12+16 APSK) adopted in the digital video broadcasting-satellite2 (DVB-S2).

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.1
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• pp.48-52
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• 2017

This paper proposes a hybrid algorithm of space-time block coding and space-frequency block coding using alternate time switch. The traditional alternate time-switched space-time or space-frequency block coding technique for orthogonal frequency division multiplexing system does not provide a good performance with a variety of communication environments. This hybrid algorithm has searched good performance ranges in various environments in view points of mobile speed and doppler frequency. In this paper, we investigate better performance ranges for two algorithms, suggest a hybrid algorithm for dynamically changing communication environments, propose a structure for transmitter and receiver, and show that its performance is better than the traditional algorithm by simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.640-650
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• 2004

Channel estimation schemes are proposed for Multiple Input-Multiple output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) systems based on the physical layer specification of the IEEE 802.1 la. By combining the space-time block coding(STBC)/ space-frequency block coding(SFBC) techniques with the transform domain interpolation, the proposed algorithms achieve more accurate channel coefficients for the MIMO channels such that improve the BER performance. The performance improvements of the proposed algorithms are evaluated by simulations under the various multipath fading channel environments and various transmission rates.

• 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.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.277-280
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• 2003

In this paper, we analyze the performance of transmitter and receiver of W-CDMA system using the channel coding and space time code in downlink over ITU-R realistic channel model. We can improve the reliability of communications and increase the data rate by channel coding, and we can get a diversity gain by using the space time code over fading channels. We also apply the RAKE receiver to improve tile performance in multi-Path fading channel environment.