• Current Optics and Photonics
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• v.2 no.2
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• pp.165-171
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• 2018

Fourier ptychographic microscopy (FPM) is a recently proposed computational imaging method that achieves both high resolution (HR) and wide field of view. In the FPM framework, a series of low-resolution (LR) images at different illumination angles is used for high-resolution image reconstruction. On the basis of previous research, image noise can significantly degrade the FPM reconstruction result. Since the captured LR images contain a lot of dark-field images with low signal-to-noise ratio, it is very important to apply a noise-reduction process to the FPM raw dataset. However, the thresholding method commonly used for the FPM data preprocessing cannot separate signals from background noise effectively. In this work, we propose an improved thresholding method that provides a reliable background-noise threshold for noise reduction. Experimental results show that the proposed method is more efficient and robust than the conventional thresholding method.

• The KIPS Transactions:PartB
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• v.16B no.1
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• pp.63-70
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• 2009

BCI technology is to control communication systems or machines by brain signal among biological signals followed by signal processing. For the implementation of BCI systems, it is required that the characteristics of brain signal are learned and analyzed in real-time and the learned characteristics are applied. In this paper, we detect feature vector of EEG signal on left and right hand movements based on incremental approach and dimension reduction using the detected feature vector. In addition, we show that the reduced dimension can improve the classification performance by removing unnecessary features. The processed data including sufficient features of input data can reduce the time of processing and boost performance of classification by removing unwanted features. Our experiments using K-NN classifier show the proposed approach 5% outperforms the PCA based dimension reduction.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.3
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• pp.204-209
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• 2004

A partial matched filter (PMF) for semi-coherent correlation code acquisition of the DSSS-CPFSK signal is proposed. It is a calculation-reduced structure of the hard-limited signal based FIR filter, yet its code acquisition time is equal to that of the hard-limited signal based FIR filter. The PMF eliminates duplicate calculations by utilizing the characteristic that the hard-limited DSSS-CPFSK signal has same value in several consecutive samples. For example, the PMF can achieve about 95% reduction in gate size, as compared to the hard-limited signal based FIR filter, when the modulation index of the DSSS-CPFSK signal is equal to 1.5 and the sample rate is equal to 40 sample/chip.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.253-262
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• 2003

In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

• ETRI Journal
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• v.45 no.3
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• pp.492-504
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• 2023

Researchers have recently shown an increased interest in estimating the direction-of-arrival (DOA) of wideband noncircular sources, but existing studies have been restricted to subspace-based methods. An off-grid sparse recovery-based algorithm is proposed in this paper to improve the accuracy of existing algorithms in low signal-to-noise ratio situations. The covariance and pseudo covariance matrices can be jointly represented subject to block sparsity constraints by taking advantage of the joint sparsity between signal components and bias. Furthermore, the estimation problem is transformed into a single measurement vector problem utilizing the focused operation, resulting in a significant reduction in computational complexity. The proposed algorithm's error threshold and the Cramer-Rao bound for wideband noncircular DOA estimation are deduced in detail. The proposed algorithm's effectiveness and feasibility are demonstrated by simulation results.

• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.306-315
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• 2001

In noise reduction method from noisy speech for speech recognition in noisy environments, conventional spectral subtraction method has a disadvantage which distinction of noise and speech is difficult, and characteristic of noise can't be estimated accurately. Also, noise reduction method in the wavelet transform domain has a disadvantage which loss of signal is generated in the high frequency domain. In order to compensate theme disadvantage, this paper propose spectral subtraction method in continuous wavelet transform domain which speech and non- speech intervals is distinguished by standard deviation of wavelet coefficient, and signal is divided three scales at different scale. The proposed method extract accurately characteristic of noise in order to apply spectral subtraction method by end detection and band division. The proposed method shows better performance than noise reduction method using conventional spectral subtraction and wavelet transform from viewpoint signal to noise ratio and Itakura-Saito distance by experimental.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1058-1061
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• 2002

This paper presents the method of low power optimization considering the glitch reduction in CMOS circuits. Our algorithm utilizes the information of MOS size, the load capacitance of fan-out, and input slew to calculate the output waveform by using the linear signal model. Therefore, the accurate waveform of glitch can be obtained for estimation of power dissipation caused by glitches. Our algorithm is applied to ISCAS’85 benchmark circuits and experimental results show 23% glitch reduction and 11% total power reduction.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.35-38
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• 2000

Since the telemanipulator consisting of high reduction ratio gear joints has a slow dynamics comparing with the master manipulator, its control signal is likely to be saturated resulting in poor tracking performance and deteriorated stability. This paper proposes a bilateral control scheme of a telemanipulator having high reduction ratio, which can compensate the control input saturation. The experimental results show that the proposed control scheme has excellent performances.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.25-34
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• 2003

The research on the development of the fault monitoring system for the thermal reduction reactor has been performed preliminarily in order to support the successful operation of the thermal reduction reactor. The final task of the development of the fault monitoring system is to assure the integrity of the thermal$_3$ reduction reactor by the acoustic emission (AE) method. The objectives of this paper are to identify and characterize the fault-induced signals for the discrimination of the various AE signals acquired during the reactor operation. The AE data acquisition and analysis system was constructed and applied to the fault monitoring of the small- scale reduction reactor, Through the series of experiments, the various signals such as background noise, operating signals, and fault-induced signals were measured and their characteristics were identified, which will be used in the signal discrimination for further application to full-scale thermal reduction reactor.

• Analytical Science and Technology
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• v.5 no.3
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• pp.277-283
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• 1992

Acid effects on the ICP-AES signals are studied as the concentrations of nitric acid, hydrochloric acid, sulfuric acid, and 1:1 mixture of nitric acid and hydrochloric acid are changed. Almost all analyte signals are depressed. The extent of the depression due to the pressence of the acids became to be pecular when the acid concentration was over 1%. Among the acids used, the suppression due to sulfuric acid is most severe and unexpectable. The ratios of the analyte signal to Ar signal and the Mg II signal to Mg I signal are measured as the concentration of the acids changed. In this study, it is proved that the main reason of the signal reduction is the change in the nebulization efficiency, for example, droplet size distribution, viscosity and surface tension variation, not the alteration of plasma excitation characteristics. There was no relationship found between ionization potential and analyte signal reduction in ICP-MS.