• Journal of the Institute of Convergence Signal Processing
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• v.7 no.3
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• pp.130-135
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• 2006

There have been experiments dealing with the possibility of the actualization of the ANC system by means of operating the DSP adaptation filter. This filter is composed of various filters(including X-LMS algorithm, Filter-U algorithm, and Full-Feedback-Filter-U algorithm) that use ventilation fans and loudspeakers as a primary source in a circular duct as an experimental device. In this operation, the ANC system using the X - LMS algorithm was found to be more effective in reducing noise than without such system. When applying the input signal of the DSP board Full Feedback-Filtered-U algorithm system while having in mind that the additionally installed second control signal was gone through feedback and mixed into the detection microphone installed near the ventilation fan when using the first ventilation fan, the system was not emitted, but maintained stable during the operation of the control filter. At this point, noise tended to decrease at a maximum of l0dB compared to other algorithms at the frequency band of 170-250Hz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.143-149
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• 2008

A novel compact model for a five-port transformer balun is proposed for the efficient circuit design of hybrid balun. Compared to the conventional model, the proposed model provides much faster computation time and more reasonable values for the extracted parameters. The hybrid balun, realized in $0.18\;{\mu}m$ CMOS, achieves 2.8 dB higher gain and 1.9 dB lower noise figure than its passive counterpart only at a current consumption of 0.67 mA from 1.2 V supply. By employing the hybrid balun, a differential zero-IF receiver is designed in $0.18\;{\mu}m$ CMOS for IEEE 802.15.4 ZigBee applications. It is composed of a differential cascode LNA, passive mixers, and active RC filters. Comparative investigations on the three receiver designs, each employing the hybrid balun, a simple transformer balun, and an ideal balun, clearly demonstrate the advantages of the hybrid balun in fully differential CMOS RF receivers. The simulated results of the receiver with the hybrid balun show 33 dB of conversion gain, 4.2 dB of noise figure with 20 kHz of 1/f noise corner frequency, and -17.5 dBm of IIP3 at a current consumption of 5 mA from 1.8 V supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.379-388
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• 2007

This paper presents a real-time respiration and heartbeat detector comprised of a 1.6 GHz single-channel Doppler sensor and analog/digital signal processing block for remote vital sign detection. The RF front end of the Doppler sensor consists of an oscillator, mixer, low noise amplifier, branch-line hybrid and patch antenna. We apply artificial transmission lines(ATLs) to the branch-line hybrid, which leads to a size reduction of 40 % in the hybrid, while its performance is very comparable to that of a conventional hybrid. The analog signal conditioning block is implemented using second order Sallen-Key active filters and the digital signal processing block is realized with a LabVIEW program on a computer. The respiration and heartbeat detection is demonstrated at a distance of 50 cm using the developed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.172-178
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• 1986

The recent interest in the design of filters is motivatied by the fact that such filter can be fully integrated using standard metal-oxide-semiconductor processing technology. This is due to replacing all the resistors in the active RC filter network by the switched capacitors. The voltage gain of a SC filter depends only on the rations of capacitance and these ratios can be obtained and maintained to high accuracy. Therefore, it is known that a switched capacitor is much better than a resistor in temperature and linearity characteristics. This paper proposed a programmable SC filter and proved the fact that ${omega}_0$ Q and G of this circuit can be controlled by digital signal. Experiments show that SC filter remains the low sensitivities but it can't avoid little influence of parasitic capacitance. As the transfer characteristic of the SC filter is varied with sampling frequency and resistor array, SC filtering technigue can be applied for digital processing, speech analysis and synthesis and so on.

• Journal of The Korean Astronomical Society
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• v.52 no.6
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• pp.235-244
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• 2019

We present the results of near-infrared imaging observations of the galaxy overdensity around the z = 1.44 radio-loud active galactic nucleus (AGN) 6CE1100+3505, which was carried out with the purpose of sampling the redshifted Hα emission from the actively star-forming galaxies that could constitute the overdensity. The existence of the structure around this AGN was spectroscopically confirmed by previous grism observations which are however limited to the central region. Using the CH4Off narrow/medium-band and H broad band filters in the Wide Infrared Camera (WIRCam) on the Canada-France-Hawaii Telescope (CFHT), we constructed a sample of objects that show a flux excess in the CH4Off band due to line emission. The emission line flux is ~ 4.9 × 10^-16 erg s^-1 cm^-2, corresponding to a star formation rate (SFR) of ~ 50 M_⊙ yr^-1 for galaxies at redshifts z ~ 1.4. None of the galaxies with medium-band flux excess is located within 1 Mpc from the central AGN, and there is no evidence that the selected galaxies are associated with the proposed cluster. Along with the star formation quenching near the center that was found from the previous grism observations, the lack of extreme starbursts in the structure suggests that at z ~ 1.4, overdense regions are no longer favorable locations for vigorous star formation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1151-1156
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• 2012

In this paper, the baseband filter is proposed in order to maintain a constant sensitivity regardless of distances for 77 GHz automotive radar system. Using existing DCOC loop circuit can remove DC offset and also cancel differences of received power depending on the distance. Measured results show that the maximum gain is 51 dB and high pass cutoff frequency can be tuned from 5 kHz to 15 kHz. The slope of high pass filter can be tuned from -10 to -40 dB/decade for the distance compensation. The measured NF and IIP3 are 26 dB and +4.5 dBm with 4.3 mA at 1.0 V supply voltage, respectively. The fabricated die size $500{\mu}m{\times}1,050{\mu}m$ excluding the in/out pads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.753-759
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• 2020

A modified Chebyshev lowpass filter function with progressively diminishing ripples in the passband is proposed and analyzed in the frequency domain. Owing to the diminishing ripples, the passband magnitude characteristic of the proposed Chebyshev function has improved compared to the classical Chebyshev function. In addition, the phase characteristics of the proposed Chebyshev function were improved considerably compared to that of the Chebyshev function, and the time delay of the proposed function was much simpler and flatter. In addition, the proposed Chebyshev filter was realizable by the passive doubly terminated ladder network delivering maximum power transfer for the order n, even or odd, thus making themselves amenable to low-sensitivity active RC or switched capacitor filters through the simulation techniques. To verify the proposed Chebyshev filter characteristics, a 6th order passive doubly terminated ladder lowpass filter was designed and analyzed using the MATLAB and SPICE program. Thus, the proposed Chebyshev function can remove the drawbacks of the classical Chebyshev function and could be applicable to the design of a filter with an improved filter size, phase, and time delay characteristics for various signal processing.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.2 s.308
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• pp.63-71
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• 2006

Denoising and reconstruction of color images are extensively studied in the field of computer vision and image processing. Especially, denoising and reconstruction of color face images are more difficult than those of natural images because of the structural characteristics of human faces as well as the subtleties of color interactions. In this paper, we propose a denoising method based on PCA reconstruction for removing complex color noise on human faces, which is not easy to remove by using vectorial color filters. The proposed method is composed of the following five steps: training of canonical eigenface space using PCA, automatic extraction of facial features using active appearance model, relishing of reconstructed color image using bilateral filter, extraction of noise regions using the variance of training data, and reconstruction using partial information of input images (except the noise regions) and blending of the reconstructed image with the original image. Experimental results show that the proposed denoising method maintains the structural characteristics of input faces, while efficiently removing complex color noise.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.69-75
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• 2004

This work proposes an 8b 220 MS/s 230 mW 3-stage pipeline CMOS ADC with on-chip filers for temperature- and power- insensitive voltage references. The proposed RC low-pass filters improve switching noise performance and reduce reference settling time at heavy R & C loads without conventional off-chip large bypass capacitors. The prototype ABC fabricated in a 0.25 um CMOS occupies the active die area of 2.25 $\textrm{mm}^2$ and shows the measured DNL and INL of maximum 0.43 LSB and 0.82 LSB, respectively. The ADC maintains the SNDR of 43 dB and 41 dB up to the 110 MHz input at 200 MS/s and 220 MS/s, respectively, while the SNDR at the 500 MHz input is degraded as much as only 3 dB than the SNDR at the 110 MHz input.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.1-8
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• 2012

The current paper presents a novel control strategy of a three-phase, four-wire Unified Power Quality (UPQC) to improve power quality. The UPQC is realized by the integration of series and shunt active power filters (APF) sharing a common dc bus capacitor. The realization of shunt APF is carried out using a three-phase, four-leg Voltage Source Inverter (VSI), and the series APF is realized using a three-phase, three-leg VSI. To extract the fundamental source voltages as reference signals for series APF, a zero-crossing detector and sample-and-hold circuits are used. For the control of shunt APF, a simple scheme based on the real component of fundamental load current (I $Cos{\Phi}$) with reduced numbers of current sensors is applied. The performance of the applied control algorithm is evaluated in terms of power-factor correction, source neutral current mitigation, load balancing, and mitigation of voltage and current harmonics in a three-phase, four-wire distribution system for different combinations of linear and non-linear loads. The reference signals and sensed signals are used in a hysteresis controller to generate switching signals for shunt and series APFs. In this proposed UPQC control scheme, the current/voltage control is applied to the fundamental supply currents/voltages instead of fast-changing APF currents/voltages, thus reducing the computational delay and the required sensors. MATLAB/Simulink-based simulations that support the functionality of the UPQC are obtained.