• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.497-504
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• 2002

The characteristics of harmonic phase angles and phase angle differences contained in earthquake ground motions such as El Centre 1940 NS, Taft1 1952 NS, Hachinohe 1968 NS and Mexico 1985 are figured, which have been mostly overlooked in contrast with the importance placed on harmonic amplitudes. Recently, performance based design method is used for seismic design and seismic retrofitting, which needs nonlinear response analysis, there must be earthquake ground accelerations which contain the phase angle and the phase angle difference characteristics of the zone considered to be constructed building structures. To make clear the importance of phase angle differences, 4-earthquake ground motions are normalized by 200 gal and nonlinear response characteristics of normalized 4-earthquake ground motions are compared.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.3
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• pp.152-158
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• 2001

This paper proposes a simple feedforward compensator in order to decrease the amount of undershoots and overshoots on the step response in nonminimum phase systems. The compensator makes the step type input be a ramp input with saturation for 0$\leq$t<${\alpha}$. It is shown in this paper that the compensated system has small amount of undershoot and overshoot at the price of rise time compared to the system without compensator. Also, provided the system is properly stable, the influence of the design parameter ${\alpha}$ on the step response of the nonminimum phase system is investigated in the case of Type A, and Type B undershoot, which gives a guideline for the compensator design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.253-257
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• 2003

Theoretical-numerical analysis of wave instability is conducted with parametric response function model. Fluctuating instantaneous mass evaporation rate functionally coupled with pressure perturbations with phase lag is assumed to examine the validity of the method. With sufficiently large amplitude and less phase lag to perturbation, combustion response is resonant to pressure waves, unstable waves are amplified, and the system is driven to instability. Magnitude of response is a crucial instability parameter in the determination of a stability margins and makes a critical change of balancing conditions between the amplifying and damping acoustic energies. In the phase regime the unstable waves are amplified, whereas, the acoustic waves are attenuated in the out-of-phase regime. In the intermediate regime, no distinct tendency of unstable waves was determined.

• Journal of IKEEE
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• v.20 no.3
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• pp.314-317
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• 2016

Recently, efforts to maximize battery life in progress with an increase in the demand for portable devices. In this paper, we propose multi-phase buck converter with fast transient response. Multi-phase buck converter may be used for the output capacitor of small size because the ripple cancellation effect, it is possible to use an inductor having an inductance less. The portable device for quick change from standby mode to active 4-phase design structure was given a fast transient response. The proposed multi-phase buck converter was fabricated using a 0.18 um CMOS process and the supply voltage ranges from 2.7V to 3.3V, the maximum load current is 500mA and settling time is 10us.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3317-3322
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• 2007

THC(Total Hydrocarbon) emissions during cold start and warm-up phase constitute the majority of THC emissions during the FTP-75 mode. As the basic approach to improve the emission performance of Gasoline engine during transient phase, the effect of spark timing retard from MBT on THC emission characteristics is studied by engine test using a Fast response Flame Ionization Detector(FFID). A cyclic analysis of the combustion process shows that high THC emissions are produced first few cycles during the transient phase. This paper presents the results of engine performance and emission of Gasoline engine with various spark timing. consequently, This paper was focused on the combustion phenomena with various spark timing during transient phase which was analyzed by Fast response Flame Ionization Detector (FFID) equipment to measure the cyclic THC emission characteristics.

• Journal of Information Processing Systems
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• v.13 no.1
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• pp.83-94
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• 2017

Near-field source localization algorithms are very sensitive to sensor gain/phase response errors, and so it is important to calibrate the errors. We took into consideration the uniform linear array and are proposing a blind calibration algorithm that can estimate the directions-of-arrival and range parameters of incident signals and sensor gain/phase responses jointly, without the need for any reference source. They are estimated separately by using an iterative approach, but without the need for good initial guesses. The ambiguities in the estimations of 2-D electric angles and sensor gain/phase responses are also analyzed in this paper. We show that the ambiguities can be remedied by assuming that two sensor phase responses of the array have been previously calibrated. The behavior of the proposed method is illustrated through simulation experiments. The simulation results show that the convergent rate is fast and that the convergent precision is high.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.495-513
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• 2020

The correlation identification of the subsurface is a novel electrical prospecting method which could suppress stochastic noise. This method is increasingly being utilized by geophysicists. It achieves the frequency response of the underground media through division of the cross spectrum of the input & output signal and the auto spectrum of the input signal. This is subject to the spectral leakage when the cross spectrum and the auto spectrum are computed from cross correlation and autocorrelation function by Discrete Fourier Transformation (DFT, "To obtain an accurate frequency response of the earth system, we propose an improved correlation identification method which uses all phase Fast Fourier Transform (APFFT) to acquire the cross spectrum and the auto spectrum. Simulation and engineering application results show that compared to existing correlation identification algorithm the new approach demonstrates more precise frequency response, especially the phase response of the system under identification.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1523-1535
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• 2018

High-performance Phase-Locked Loops (PLLs) are critical for grid synchronization in grid-tied power electronic applications. In this paper, a new single-phase All Digital Phase-Locked Loop (ADPLL) is proposed. It features fast transient response and good robustness under distorted grid conditions. It is designed for Field Programmable Gate Array (FPGA) implementation. As a result, a high sampling frequency of 1MHz can be obtained. In addition, a new OSG is adopted to track the power frequency, improve the harmonic rejection and remove the dc offset. Unlike previous methods, it avoids extra feedback loop, which results in an enlarged system bandwidth, enhanced stability and improved dynamic performance. In this case, a new parameter optimization method with consideration of loop delay is employed to achieve a fast dynamic response and guarantee accuracy. The Phase Detector (PD) and Voltage Controlled Oscillator (VCO) are realized by a Coordinate Rotation Digital Computer (CORDIC) algorithm and a Direct Digital Synthesis (DDS) block, respectively. The whole PLL system is finally produced on a FPGA. A theoretical analysis and experiments under various distorted grid conditions, including voltage sag, phase jump, frequency step, harmonics distortion, dc offset and combined disturbances, are also presented to verify the fast dynamic response and good robustness of the ADPLL.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.547-550
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• 2001

Through matched filtering synthetic aperture radar (SAR) produces high-resolution imagery from data collected by a relative small antenna. While the impulse response obtained by the matched filter approach produces the best achievable signal-to-noise ratio, large sidelobes must be reduced to obtain higher-resolution SAR images. So, many enhancement methods of SAR imagery have been proposed. As a deconvolution method, the phase-extension inverse filtering is based on the characteristics of the matched filtering used in SAR imaging. It improves spatial resolution as well as effectively suppresses the sidelobes with low computational complexity. In the phase-extension inverse filtering, the impulse response is obtained from simulation with a point target. But in a real SAR environment, for example ERS-1, the impulse response is distorted by many non-ideal factors. So, in the phase-extension inverse filtering for a real SAR processing, the magnitudes of the frequency transfer function have to be compensated to produce more desirable results. In this paper, an estimation method to obtain a more accurate impulse response from a real SAR image is studied. And a compensation scheme to produce better performance of the phase-extension inverse filtering is also introduced.

• Natural Product Sciences
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• v.20 no.4
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• pp.301-305
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• 2014

The aim of our study is to investigate the anti-nociceptive and anti-inflammatory properties of an ethanol extract of the leaf and stem of Aralia cordata. Writhing responses induced by acetic acid, tail immersion test, and formalin-induced paw pain response for nociception and formalin-induced paw edema for inflammation were evaluated in mice. A. cordata (50 - 200 mg/kg, p.o.) and ibuprofen (100 mg/kg, p.o.), a positive non-steroidal anti-inflammatory drugs (NSAIDs), inhibited the acetic acid-induced writhing response, but they did not protect the thermal nociception in tail immersion test. However, morphine (5 mg/kg, s.c.) used as positive opioid control alleviated both the acetic acid-induced writhing response and thermal nociception in tail immersion test. In the formalin test, A. cordata (50 - 200mg/kg) and ibuprofen (200mg/kg) inhibited the second phase response (peripheral inflammatory response), but not the first phase response (central response), whereas morphine inhibited both phase pain responses. Both A. cordata (100 mg/kg) and ibuprofen (200 mg/kg) significantly alleviated the formalin-induced increase of paw thickness, the index of inflammation. These results show for the first time that the leaf and stem of A. cordata has a significant anti-nociceptive effect that seems to be peripheral, but not central. A. cordata also displays an anti-inflammatory activity in an acute inflammation model. The present study supports a possible use of the leaf and stem of A. cordata to treat pain and inflammation.