• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.397-400
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• 2000

Telecommunication system demands for increased bandwidths and operating frequencies for analog signal processing could be satisfied in the near future by the emergence of a novel technology based on magnetostatic waves propagating in low loss ferrimagnetic films. The magnetostatic wave is the only available technology for analog signal processing directly at millimeter wave frequencies. This paper has been studied the design and implementation of a Magnetostatic Surface Wave band-pass filter for LMDS system.

• Journal of applied mathematics & informatics
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• v.8 no.3
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• pp.731-742
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• 2001

A Gaussian smoothing algorithm obtained from a cascade of convolutions with a seven-point kernel is described. We prove that the change of local sums after applying our algorithm to sinusoidal signals is reduced to about two thirds of the change by the binomial coefficients. Hence, our seven point kernel is better than the binomial coefficients when trend curves are needed to be generated. We also prove that if our Gaussian convolution is applied to sinusoidal functions, the amplitude of higher frequencies reduces faster than the lower frequencies and hence that it is a low pass filter.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.98-100
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• 1991

We studied the characteristics of the compound electrode and found that the compound electrode provides the four-electrode method in a compact form. We developed a new method of measuring the skin impedance using simple electrodes at low frequencies. At high frequencies where the effect of internal tissue impedance is not negligible, we used the compensation method using compound electrodes since they measure the voltage right under the skin. At 50 kHz, we measured the real part of the skin impedance of less than $80\;{\Omega}$ on the thorax.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.10a
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• pp.74-77
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• 1984

In this paper, We have proposed the new lee weighted Hadamard transform which retains the main properties of Hadamard matrix. The non-orthogonal LWH matrix was Weighted in the center of the spatial domain. The human visual response to spatioal requencies in nonuniform and that the mid spatial frequencies are emphasized more than the low and high spatial frequencies, the faast algorithm of the Lee Weighted Hadamard transform has shown by the sparse matrix factorization.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.768-777
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• 2005

This paper shows that the performance of a nonlinear fluid engine mount can be improved by an optimal design process. The property of a hydraulic mount with inertia track and decoupler differs according to the disturbance frequency range. Since the excitation amplitude is large at low excitation frequency range and is small at high excitation frequency range, mathematical model of the mount can be divided into two linear models. One is a low frequency model and the other is a high frequency model. The combination of the two models is very useful in the analysis of the mount and is used for the first time in the optimization of an engine mount in this paper. Normally, the design of a fluid mount is based on a trial and error approach in industry because there are many design parameters. In this study, a nonlinear mount was optimized to minimize the transmissibilities of the mount at the notch and the resonance frequencies for low and high-frequency models by a popular optimization technique of sequential quadratic programming (SQP) supported by $MATLAB^{(R)}$subroutine. The results show that the performance of the mount can be greatly improved for the low and high frequencies ranges by the optimization method.

• Advances in aircraft and spacecraft science
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• v.4 no.5
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• pp.543-553
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• 2017

Vibration is a source of performance degradation in all optical imaging systems. Performance of high resolution remote sensing payloads is often limited due to satellite platform vibrations. Effects of Linear and high frequency sinusoidal vibrations on the system MTF are known exactly in closed form but the low frequency vibration effects is a random process and must be considered statistically. Usually the vibration MTF budget is defined based on the mission requirements and the overall MTF limitations. For analyzing low frequency effects, designer must know all the systems specifications and parameters. With a good understanding of harmful vibration frequencies and amplitudes in the system preliminary design phase, their effects could be removed totally or partially. This procedure is cost effective and let the designer to eliminate just harmful vibrations and avoids over-designing. In this paper we have analyzed the effects of low-frequency platform vibrations on the payload's modulation transfer function. We have used a statistical analysis to find the probability of imaging with a MTF equal or greater than a pre-defined budget for different missions. The worst and average cases have been discussed and finally we have proposed "look-up figures". Using these look-up figures, designer can choose the electro-optical parameters in such a way that vibration effects be less than its pre-defined budget. Furthermore, using the results, we can propose a damping profile based on which vibration frequencies and amplitudes must be eliminated to stabilize the payload system.

• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.50-56
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• 2007

In this study, we have performed some experimental works on the effects of variation of low, middle and high turbidity for understanding of optical characteristics which is very important factor for the turbidity measurement. The various output frequencies were obtained by the experimental apparatus which consist of detectors, a light source, a frequency counter and so on. From the result of analysis of these frequencies, Firstly, The difference of signal value for each degrees of low turbidity was the smallest of three scopes around the Nephelometric position. Second, the characteristics of each degrees of middle turbidity was proved that signal values of all degrees were larger those of low turbidity but the difference of each signal value of the forward direction was smaller than that of the backward direction. Third, the characteristics of each degrees of high turbidity was proved that though similar to the characteristics of middle turbidity, each signal value of all degrees was larger and the difference of each signal value of all degrees was smaller than those of low and middle turbidity

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.1
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• pp.1-10
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• 2010

This paper proposes a two-phase clocked adiabatic static CMOS logic (2PASCL) circuit that utilizes the principles of adiabatic switching and energy recovery. The low-power 2PASCL circuit uses two complementary split-level sinusoidal power supply clocks whose height is equal to $V_{dd}$. It can be directly derived from static CMOS circuits. By removing the diode from the charging path, higher output amplitude is achieved and the power consumption of the diode is eliminated. 2PASCL has switching activity that is lower than dynamic logic. We also design and simulate NOT, NAND, NOR, and XOR logic gates on the basis of the 2PASCL topology. From the simulation results, we find that 2PASCL 4-inverter chain logic can save up to 79% of dissipated energy as compared to that with a static CMOS logic at transition frequencies of 1 to 100 MHz. The results indicate that 2PASCL technology can be advantageously applied to low power digital devices operated at low frequencies, such as radio-frequency identifications (RFIDs), smart cards, and sensors.

• Current Optics and Photonics
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• v.7 no.4
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• pp.345-353
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• 2023

We propose a turbulence-tolerant Manchester on-off keying (M-OOK) transmission for free-space optical (FSO) communication. At the transmitter end, a M-OOK signal featuring a spectrum with low-frequency components absent is modulated and transmitted into a turbulent channel. At the receiver end, a low-pass filter (LPF) -based adaptive-threshold decision (ATD) with LPF-extracted channel-state information (CSI) and a high-pass filter (HPF)-based fixed-threshold decision (FTD) are employed to compensate for the effects of turbulence, owing to the low-frequency spectral characteristics of the turbulent channel. The performance of LPF-based ATD and HPF-based FTD are evaluated for various cutoff frequencies for the LPF and HPF. Besides, the proposed M-OOK transmission is compared to conventional non-return-to-zero OOK (NRZ-OOK) for different data rates. The proposed technique is verified in simulation. The simulation results show that the proposed M-OOK detection with optimized cutoff frequencies of LPF and HPF has better bit-error-rate (BER) performance compared to NRZ-OOK, and it is close to the theoretical ATD with the knowledge of precise CSI under various degrees of turbulence effects.

• ETRI Journal
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• v.35 no.1
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• pp.158-161
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• 2013

This letter proposes a low-power current-steering digital-to-analog converter (DAC). The proposed DAC reduces the clock power by cutting the clock signal to the current-source cells in which the data will not be changed. The 10-bit DAC is implemented using a $0.13-{\mu}m$ CMOS process with $V_{DD}$=1.2 V. Its area is $0.21\;mm^2$. It consumes 4.46 mW at a 1-MHz signal frequency and 200-MHz sampling rate. The clock power is reduced to 30.9% and 36.2% of a conventional DAC at 1.25-MHz and 10-MHz signal frequencies, respectively. The measured spurious free dynamic ranges are 72.8 dB and 56.1 dB at 1-MHz and 50-MHz signal frequencies, respectively.