• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1109-1122
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• 1996

Generally, moving images contain the various components in motions, which reange from a static object and background to a fast moving object. To extract the accurate motion parameters, we must consider the various motions. That requires a wide search egion in motion estimation. The wide search, however, causes a high computational complexity. If we have a few knowledge about the motion direction and magnitude before motion estimation, we can determine the search location and search window size using the already-known information about the motion. In this paper, we present a local adaptive motion estimation approach that predicts a block motion based on spatio-temporal neighborhood blocks and adaptively defines the search location and search window size. This paper presents a technique for reducing computational complexity, while having high accuracy in motion estimation. The proposed algorithm is introduced the forward and backward projection techniques. The search windeo size for a block is adaptively determined by previous motion vectors and prediction errors. Simulations show significant improvements in the qualities of the motion compensated images and in the reduction of the computational complexity.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.139-143
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• 2014

This paper proposes a simplified DC calculation method for simplified depth coding (SDC) mode of 3D High Efficiency Video Coding (3D-HEVC) to reduce the computational complexity. For the computational complexity reduction, the current reference software of 3D-HEVC employs reference samples sub-sampling method. However, accumulation, branch, and division operations are still utilized and these operations increase computational complexity. The proposed method calculates DC value without those operations. The experimental results show that the proposed method achieves 0.1% coding gain for synthesized views in common test condition (CTC) with the significantly reduced number of computing operations.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.20-22
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• 2007

The H.264/AVC standard developed by the joint Video Team (JVT) provides better coding efficiency than previous standards. The new emerging H.264/AVC employs variable block size motion estimation using multiple reference frame with 1/4-pel MV(Motion Vector) accuracy. These techniques are a important feature to accomplish higher coding efficiency. However, these techniques are increased overall computational complexity. To overcome this problem, this paper proposes advanced fast mode decision suited for variable block size by classifying inter mode based on Rate Distortion Optimization(RDO) technique. Proposed algorithm is going to use to implement H/W structure for fast mode decision. The experimental results shows that the proposed algorithm provides significant reduction computational complexity without any noticeable coding loss and additional computation. Entire computational complexity is decreased about 30%.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.74-83
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• 1997

In this paper, we propose a new fractal image decoding algorithm with fast convergence speed by using the data dependence and the improved initial image estimation. Conventional method for fractal image decoding requires high-degrdd computational complexity in decoding process, because of iterated contractive transformations applied to whole range blocks. On proposed method, Range of reconstruction imagte is divided into referenced range and data dependence region. And computational complexity is reduced by application of iterated contractive transformations for the referenced range only. Data dependence region can be decoded by one transformations when the referenced range is converged. In addition, more exact initial image is estimated by using bound () function in case of all, and an initial image more nearer to a fixed point is estimated by using range block division estimation. Consequently, the convergence speed of reconstruction iamge is improved with 40% reduction of computational complexity.

• Journal of Korea Multimedia Society
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• v.10 no.7
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• pp.838-845
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• 2007

In this paper, we propose a modified cubic convolution scaler for the enlargement or reduction of digital images. The proposed method has less computational complexity than the cubic convolution method. In order to reduce the computational complexity, we use the linear function of the cubic convolution and the difference value of adjacent pixels for selecting interpolation methods. We employ adders and barrel shifts to calculate weights of the proposed method. The proposed method is compared with the conventional one for the computational complexity and the image quality. It has been designed and verified by HDL(Hardware Description Language), and synthesized using Xilinx Virtex FPGA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1172-1180
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• 2007

OFDM system has very good high spectral efficiency and the robustness to the frequency-selective fading. Because of the high PAPR, OFDM signals can be distorted in nonlinear HPA(High Power Amplifier). So, to overcome the nonlinear distortion, it is very important to reduce the IMD value. With respect to the BER performance, IMD reduction method is better than the PAPR reduction method. However, IMD reduction method has much more system complexity because of the additional FFT processor in transmitter. In this paper, we study the OFDM communication system based on the IMD reduction method using SPW method. A new IMD reduction method is proposed to reduce the computational complexity. SPW method is to divide the input OFDM data into several sub-blocks and to multiply phase weighting values with each sub-blocks for the reduction of PAPR or IMD. Unlike the conventional method, the system size and computational complexity can be reduced.

• ETRI Journal
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• v.35 no.4
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• pp.714-717
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• 2013

Peak power reduction techniques in orthogonal frequency division multiplexing (OFDM) has been an important subject for many researchers for over 20 years. In this letter, we propose a side-information-free technique that is based on the concept of random variable (RV) transformation. The suggested method transforms RVs into other RVs, aiming to reshape the constellation that will consequently produce OFDM symbols with a reduced peak-to-average power ratio. The proposed method has no limitation on the mapping type or the mapping order and has no significant effect on the bit error rate performance compared to other methods presented in the literature. Additionally, the computational complexity does not increase.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.93-96
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• 2022

DTW can eliminate gaps between sequences of different lengths and find out the similarity of patterns, but due to the time and space complexity, it requires a high computational cost on large datasets. In this paper, we propose a DDTW algorithm that not only reduces computational costs but also has no error in the results. In addition, the algorithm complexity of DTW and DDTW is compared by measuring the computational time according to the length of the sequence. Simulation results show a noticeable reduction in computational time in DDTW compared to DTW.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.22-28
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• 2015

In this paper, we propose a new computationally efficient joint iterative multi-input multi-output (MIMO) detection scheme using a soft interference cancellation and minimum mean squared-error (SIC-MMSE) method. The critical computational burden of the SIC-MMSE scheme lies in the multiple inverse operations of the complex matrices. We find a new way which requires only a single matrix inversion by utilizing the Taylor series expansion of the matrix, and thus the computational complexity can be reduced. The computational complexity reduction increases as the number of antennas is increased. The simulation results show that our method produces almost the same performances as the conventional SIC-MMSE with reduced computational complexity.

• ETRI Journal
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• v.36 no.3
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• pp.407-417
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• 2014

A new-generation video coding standard, named High Efficiency Video Coding (HEVC), has recently been developed by JCT-VC. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. However, one the most important challenges in HEVC is time complexity. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. This provides a high encoding quality, but also causes computational complexity. We focus on a reduction scheme of the computational complexity and propose a new approach that can terminate the quadtree-based structure early, based on the RD costs of the parent and current levels. Our proposed algorithm is compared with HEVC Test Model version 10.0 software and a previously proposed algorithm. Experimental results show that our algorithm provides a significant time reduction for encoding, with only a small loss in video quality.