• Journal of Digital Contents Society
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• v.8 no.3
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• pp.385-391
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• 2007

In this paper, we propose a frequency synchronization algorithm for S-DMT cable modem, which is practicable to the next-generation high capacity upstream physical layer in HFC networks. Analyzing several viable frequency synchronization algorithms of multicarrier systems, we proposed an algorithm using predetermined training sequence of repeated pattern in preamble field and residual frequency offset compensation with pilot signals. We verified that the simulation results of the proposed algorithm in AWGN showed good performance and suitability to the S-DMT upstream cable modem for fast frequency synchronization.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.30-41
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• 2020

Lines and textures are natural properties of the surface of natural objects, and their images can be sparsely represented in suitable frames such as wavelets, curvelets and wave atoms. Based on characteristics that the curvelets framework is good at expressing the line feature and wavesat is good at representing texture features, we propose a model for the weighted sparsity constraints of the two frames. Furtherly, a multi-step iterative fast algorithm for solving the model is also proposed based on the split Bergman method. By introducing auxiliary variables and the Bergman distance, the original problem is transformed into an iterative solution of two simple sub-problems, which greatly reduces the computational complexity. Experiments using standard images show that the split-based Bergman iterative algorithm in hybrid domain defeats the traditional Wavelets framework or curvelets framework both in terms of timeliness and recovery accuracy, which demonstrates the validity of the model and algorithm in this paper.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.615-618
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• 2011

Living cells generate the cell cycle or apoptosis, depending on the course will be repeated. If an error occurs during this period of life in order to maintain the cells in the peripheral cells find the error portion. These cellular functions were applied to the system to simulate the circuit. Circuit implementation of the present study was constructed the redundant structure in order to found the error quickly. Self-repairing of digital systems as an advanced form of fault-tolerance has been increasingly receiving attention according as digital systems have been more and more complex and speed-up especially for urgent systems or those working on extreme environments such as deep sea and outer space. Simulating the process of cell differentiation algorithm was confirmed by the FPGA on the counter circuit. If an error occurs on the circuit where the error was quickly locate and repair. In this paper, we propose a novel self-repair architecture for fast and robust fault-recovery that can easily apply to real, complex digital systems. These Self-Repairing Algorithms make it possible for the application digital systems to be alive even though in very noisy and extreme environments.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.507-516
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• 2014

We present a hybrid method for spectral reflectivity recovery, using 3D extrapolation as a supplemental method for 3D interpolation. The proposed 3D extrapolation is an extended version of 3D interpolation based on the barycentric algorithm. It is faster and more accurate than the conventional spectral-recovery techniques of principal-component analysis and nonnegative matrix transformation. Four different extrapolation techniques (based on nearest neighbors, circumcenters, in-centers, and centroids) are formulated and applied to recover spectral reflectivity. Under the standard conditions of a D65 illuminant and 1964 $10^{\circ}$ observer, all reflectivity data from 1269 Munsell color chips are successfully reconstructed. The superiority of the proposed method is demonstrated using statistical data to compare coefficients of correlation and determination. The proposed hybrid method can be applied for fast and accurate spectral reflectivity recovery in image processing.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.902-907
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• 2011

In this paper, we deal with performance evaluation of visual path following using 2D and 3D information. Visual path follow first teaches driving path by selecting milestone images then follows the same route by comparing the milestone image and current image. We follow the visual path following algorithm of [8] and [10]. In [8], a robot navigated with 2D image information only. But in [10], local 3D geometries are reconstructed between the milestone images in order to achieve fast feature prediction which allows the recovery from tracking failures. Experimental results including diverse indoor cases show performance of each algorithm.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2212-2220
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• 2016

Based on the conventional PID algorithm and the adaptive PID (AD-PID) algorithm, a separate sampling adaptive PID (SSA-PID) algorithm is proposed to improve the transient response of digitally controlled DC-DC converters. The SSA-PID algorithm, which can be divided into an oversampled adaptive P (AD-P) control and an adaptive ID (AD-ID) control, adopts a higher sampling frequency for AD-P control and a conventional sampling frequency for AD-ID control. In addition, it can also adaptively adjust the PID parameters (i.e. $K_p$, $K_i$ and $K_d$) based on the system state. Simulation results show that the proposed algorithm has better line transient and load transient responses than the conventional PID and AD-PID algorithms. Compared with the conventional PID and AD-PID algorithms, the experimental results based on a FPGA indicate that the recovery time of the SSA-PID algorithm is reduced by 80% and 67% separately, and that overshoot is decreased by 33% and 12% for a 700mA load step. Moreover, the SSA-PID algorithm can achieve zero overshoot during startup.

• ETRI Journal
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• v.42 no.6
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• pp.922-931
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• 2020

A hierarchical iterative algorithm for the canonical polyadic decomposition (CPD) of tensors is proposed by improving the traditional conjugate gradient least squares (CGLS) method. Methods based on algebraic operations are investigated with the objective of estimating the direction of arrival (DoA) and polarization parameters of signals impinging on an array with electromagnetic (EM) vector-sensors. The proposed algorithm adopts a hierarchical iterative strategy, which enables the algorithm to obtain a fast recovery for the highly collinear factor matrix. Moreover, considering the same accuracy threshold, the proposed algorithm can achieve faster convergence compared with the alternating least squares (ALS) algorithm wherein the highly collinear factor matrix is absent. The results reveal that the proposed algorithm can achieve better performance under the condition of fewer snapshots, compared with the ALS-based algorithm and the algorithm based on generalized eigenvalue decomposition (GEVD). Furthermore, with regard to an array with a small number of sensors, the observed advantage in estimating the DoA and polarization parameters of the signal is notable.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1248-1255
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• 2003

High-speed QPSK demodulator has been one important design objective of any wireless communication systems, especially those offering broadband multimedia service. This paper describes Zero-Crossing IF-level(ZCIF) QPSK demodulator for high-speed wireless communications, and its hardware structures are discussed. ZCIF QPSK demodulator is mainly composed of symbol time circuit and carrier recovery circuit to estimate timing and phase-offsets. There are various schemes. Among them, we use Gardner algorithm and Decision-Directed carrier recovery algorithm which is most efficient scheme to warrant the fast acquisition and tracking to fabricate FPGA chip. The testing results of the implemented onto CPLD-FLEX10K chip show demodulation speed is reached up to 2.6［Mbps］. Actually in case of designing by ASIC, its speed may be faster than CPLD by 5 times. Therefore, it is possible to fabricate the ZCIF QPSK demodulator with speed of 10 Mbps.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.616-619
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• 1997

The spectrum-recovery scheme in Hadamard transform spectroscopy is commonly implemented with a fast Hadamard transform (FHT). When the Hadamard or simplex matrix corresponding to the mask does not have the same ordering as the Hadamard matrix corresponding to the FHT, a modification is required. When the two Hadamard matrices are in the same equivalence class, this modification can be implemented as a permutation scheme. This paper investigates permutation schemes for this application. This paper is to relieve the confusion about the applicability of existing techniques, reveals a new, more efficient method: and leads to an extension that allows a permutation scheme to be applied to any Hadamard or simplex matrix in the appropriate equivalence class.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.397-404
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• 2006

As an increase in recent optical network-based IP services, GMPLS management framework becomes more important than ever before. In this paper, we propose the dynamic GMPLS path management algorithm, which can satisfy the users with their traffic engineering recovery requirements and find out the best backup service path under multiple link failures. To be more specific, we are deriving the soluble conditions of a backup path which is satisfied in a GMPLS network. In addition, through proposing the fast backup path selection algorithm, we can sufficiently satisfy a user's recovery requirement and minimally protect the suspension of the service against a link failure.