• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.150-153
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• 2014

영상 표시 장치에서 대조 이미지의 왜곡 현상을 보완하기 위해 히스토그램 평활화(Histogram Equalization)와 플래토 평활화(Plateau Equalization)가 사용된다. 히스토그램 평활화(Histogram Equalization)를 이용하여 명암대비를 증가 시킬 경우 과도한 이미지의 밝기 변화에 따른 과포화 현상이 발생하며 실시간 시스템에서는 물체 추적에 왜곡 현상이 발생한다. 특히, 적외선 영상(infrared image)과 같이 명암비가 한쪽으로 치우쳐 있는 영상들을 명암비를 개선하기 위해서는 플래토 평활화(Plateau Equalization)와 같은 영상 개선 방법이 필수적이다. 플래토 평활화에서는 임계값을 사용하는 방법이 제시되고 있지만 실험에 의한 최적 임계값을 찾아내는 방식이며, 이 방법은 입력되는 새로운 영상마다 임계값을 실험에 의해 매번 반복해서 도출해야 문제점이 있다. 본 논문에서 제안하는 방법은 과포화 되는 이미지 영역의 문제를 해결하기 위해 제시하는 방법으로 히스토그램 평활화(Histogram Equalization)의 동적 분할하는 알고리즘에 근거하되, 입력 영상에따라 적응적으로 임계값을 설정하는 기법을 제안한다. 실험을 통해 제안하는 방법이 실시간 영상에서 기존의 동적분할 히스토그램에 비해 자연스럽게 명암비를 개선하여 과포화 되거나 중요한 정보를 누락하여 왜곡 되지 않게 자연스러운 화면을 재생하는 방법을 제안한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.233-237
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• 1988

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1990.10a
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• pp.23-28
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• 1990

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.105-111
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• 2017

This paper compares the SE-MMA (Signed Error-MMA) and QE-MMA (Quantized Error-MMA) adaptive equalization algorithm in order to compensates the intersymbol interference due to channel in the transmission of spectral efficient nonconstant modulus signal such as 16-QAM. In the currently MMA adaptive equalizer, the error signal is needed for the updating the tap coefficient. The SE-MMA uses the polarity of error signal for reduce the computational operation in that process, the QE-MMA consider the this polarity and finite bit power-of-2 quantized component in that process, so they has different equalization performance. In order to comparing these performance, the computer simulation was performed in the same channel and environment, the output signal constellation of equalizer, residual isi and maximum distortion, MSE, SER were applied. As a result of computer simulation, the QE-MMA have more superior performance than the SE-MMA in every performance index.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.101-106
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• 2020

This paper relates with the VS-QE-MMA (Varying Stepsize-Quantized Error-MMA) based on the varying stepsize for improving the equalization performance in the QE-MMA adaptive equalization algorithm that is possible to reducing the intersymbol interference occurred at channel. The SE-MMA use the high-order statistics of transmitted signal and sign of error signal. The QE-MMA was appeared for the H/W implementation easiness substitutes the multiplication and substraction into the shift and substraction in the updating the tap coefficient based on the power-of-two operation of error signal magnitude. The QE-MMA gives degradation of equalization performance due to the such simplification of arithmetic operation. For improving this problem, the propose algorithm, namely VS-QE-MMA, applies the varying stepsize of the nonlinear transformation of error signal. It was confirmed by simulation that the VS-QE-MMA gives better performance than current QE-MMA in the same channel and signal to noise ratio. As a result of simulation, the VS-QE-MMA has more better performance in the every performance index, and it was also confirmed that the varying stepsize effect can be obtained in the greater than 10dB of signal to noise ratio.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.111-116
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• 2018

This paper compare the adaptive equalization performance of RMMA (Region-based MMA) and SCA (Square Contour Algorithm) in order to minimize the intersymbol interference that is occurred in communication channel when transmit the multilevel QAM signal. The RMMA used for improving the performance by translate to 4-level constant modulus and stability in current MMA algorithm, and the SCA used for the improving the performacne by combines the current CMA and RCA algorithm. These algorithms are aimed to improving the equalization peformance by applying the differenct principle each other in multilevel QAM signal, its different performance were compared by computer simulation in the same channel environment. For this, the output signal constellation of equalizer, residual isi, maximum distortion were applied in performance index. As a result, RMMA have more fairly good in every performance index such as signal point clustering capabilities and convergence speed compared to SCA. It is confired that the equalization noise due to misadjumstment was reduced in RMMA than SCA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.115-121
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• 2019

In this paper, we propose MSAG-SCS-MMA-I adaptive blind equalization with double step size with very small residual ISI and MSE at steady-state while significantly improving the convergence speed of the traditional SCS-MMA-I algorithm in 256-QAM system. And we evaluate the equalization performance for this algorithm. Different step sizes according to the absolute value of decision-directed error instead of a fixed step-size are applied to the tap update equation of MSAG-SCS-MMA-I, which is controlled by binary flags of '1' or '0' obtained from SCS-MMA-I and decision-directed algorithms. This makes for excellent equalization performance. As a result of computer simulation, we confirmed that the proposed algorithm has more better performance than the MMA, SCS-MMA-I, and MSAG-SCS-MMA-I algorithms in terms of the performance index such as residual ISI, MSE, and MD.

• Journal of Internet Computing and Services
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• v.14 no.1
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• pp.9-14
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• 2013

The criterion of zero-error probability provides a limitation on error probability functions being used for adaptive systems when the error samples are shifted by the influence of DC-bias noise. In this paper, we employ a bias term in the error distribution and propose a new criterion of the biased zero-error probability with error being zero. Also, by maximizing the proposed criterion on expanded filter structures, a supervised adaptive algorithm has been derived. From the simulation results of supervised equalization, the algorithm based on the proposed criterion yielded zero-centered and highly concentrated error samples without disturbance in the environments of strong impulsive and DC-bias noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.2998-3017
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• 2018

Massive (large-scale) MIMO (multiple-input multiple-output) is one of the key technologies in next-generation wireless communication systems. This paper proposes a high-performance low-complexity turbo receiver for SC-FDMA (single-carrier frequency-division multiple access) based MMIMO (massive MIMO) systems. Because SC-FDMA technology has the desirable characteristics of OFDMA (orthogonal frequency division multiple access) and the low PAPR (peak-to-average power ratio) of SC transmission schemes, the 3GPP LTE (long-term evolution) has adopted it as the uplink transmission to meet the demand high data rate and low error rate performance. The complexity of computing will be increased greatly in base station with massive MIMO (MMIMO) system. In this paper, a low-complexity adaptive turbo equalization receiver based on normalized minimal symbol-error-rate for MMIMO SC-FDMA system is proposed. The proposed receiver is with low complexity than that of the conventional turbo MMSE (minimum mean square error) equalizer and is also with better bit error rate (BER) performance than that of the conventional adaptive turbo MMSE equalizer. Simulation results confirm the effectiveness of the proposed scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.4
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• pp.13-19
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• 2000

With the rapid development of the information communication technology, more and more distribution multimedia data and electronic publishing in the web, has created a need for the copyright protection with authentication of digital information. In this paper, we propose a multi-watermarking adding and adaptive spectral watermark algorithm well adaptive frequency domain of each hierarchical using orthogonal forward wavelet transform(FWT. Numerical test results, created watermarking image robustness not only image transform such as low-pass filtering, bluring, sharpen filtering, wavelet compression but also brightness, contrast gamma correction, histogram equalization, cropping.