• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1065-1072
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• 2012

In this paper, the method of design of the waveguide band-pass filter and limiter in radar system is proposed. First, we design a self-resonant iris, which can behave as a band-pass filter by mounting the PIN diode on the iris. When low power microwave is incident on the proposed element, the element behaves as a band-pass filter. Under a high power microwave condition, however, the element behaves as a limiter having wide band stop characteristics. The fabricated element has a pass band with -0.7 dB insertion loss at 10 GHz under the low power condition and isolation about 25 dB under the high power condition.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.159-162
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• 2005

Recently, due to rapid developments of wireless communication and digital TV, modern society needs to process of aquisition, storage and transmission of much information. So the importance of signal processing is increasing and various digital filters are used in the two-dimensional signal such as image. And kinds of these digital filters are IIR(infinite impulse response) filter and FIR(finite impulse response) filter. And FIR filter which has the phase linearity, the easiness of creation and stability is applied to many fields. In design of this FIR filter, flatness property is a important factor in pass-band and stop-band. In this paper, we designed a 2-D Circular FIR filter using the Bernstein polynomial, it is presented flatness property in pass-band and stop-band. And we simulated the designed filter with noisy test image and compared the results with existing methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1255-1260
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• 2009

Microstrip interdigital filter is designed with the width and length of a resonator, the gap distance between resonators and the location of a tap. When designing filters, it is a benefit to design with few design parameters comparing to many design parameters. In this paper we design and implement two microstrip interdigital filters operating in the UWB(Ultra Wide-Band) frequency band, one using a fixed width of a resonator and the other using a different width of resonators. The test results of the implemented filters show that the low-band high filter with a fixed width has the insertion loss of 1.49dB, -10dB band width of 720MHz, -35.7dBattenuation at 4.8GHzand below -13dB of S11. The filter with a different width of resonators has the insertion loss of 1.6dB, -10dBbandwidth of 1.63GHz and below-8dBof S11.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.109-116
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• 2022

In this paper, we propose a band rejection filter (BRF) with a state variable filter (SVF) structure to effectively remove the influence of 60 Hz line frequency noise introduced into the sensor system. The conventional BRF of the SVF structure uses an additional operational amplifier (OPAMP) to add a low pass filter (LPF) output and a high pass filter (HPF) output or an input signal and a band pass filter. Therefore, the notch frequency and the notch depth that determine the signal attenuation of the BRF greatly depend on the tolerance of the resistors used to obtain the sum or difference of the signals. On the other hand, in the proposed BRF, since the BRF output is formed naturally within the SVF structure, there is no need for a combination between each port. The notch frequency of the proposed BRF is 59.99 Hz, and it can be confirmed that it is not affected at all by the tolerance of the resistor through the Monte Carlo simulation results. The notch depth also has an average of -42.54dB and a standard deviation of 0.63dB, confirming that normal operation as a BRF is possible. Also, with the proposed BRF, noise filtering was applied to the electrocardiogram (ECG) signal that interfered with 60 Hz noise, and it was confirmed that the 60 Hz noise was appropriately suppressed.

• ETRI Journal
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• v.42 no.5
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• pp.781-789
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• 2020

In this study, an E-band low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) has been designed using silicon-germanium 130-nm bipolar complementary metal-oxide-semiconductor technology to suppress unwanted signal gain outside operating frequencies and improve the signal gain and noise figures at operating frequencies. The proposed impedance-controllable filter has series (R_s) and parallel (R_p) resistors instead of a conventional inductor-capacitor (L-C) filter without any resistor in an interstage matching circuit. Using the impedance-controllable filter instead of the conventional L-C filter, the unwanted high signal gains of the designed E-band LNA at frequencies of 54 GHz to 57 GHz are suppressed by 8 dB to 12 dB from 24 dB to 26 dB to 12 dB to 18 dB. The small-signal gain S₂₁ at the operating frequencies of 70 GHz to 95 GHz are only decreased by 1.4 dB to 2.4 dB from 21.6 dB to 25.4 dB to 19.2 dB to 24.0 dB. The fabricated E-band LNA MMIC with the proposed filter has a measured S₂₁ of 16 dB to 21 dB, input matching (S₁₁) of -14 dB to -5 dB, and output matching (S₂₂) of -19 dB to -4 dB at E-band operating frequencies of 70 GHz to 95 GHz.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.665-672
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• 2015

We demonstrate an ultrathin metamaterial for polarization independent perfect absorption as well as a band-pass filter (BPF) which works at a higher frequency band compared to the perfect absorption band. The planar metamaterial is comprised of three layers, symmetric split ring resonators (SSRRs) at the front and structured ground plane (SGP) at the back separated by a dielectric layer. The perfect metamaterial absorber (MA) can realize near 100% absorption due to high electromagnetic losses from the electric and/or magnetic resonances within a certain frequency band. The thickness of the structure is only 1/28 of the maximum absorption wavelength.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.405-408
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• 2002

Because of superior division among sub-channels, DWT MC-CDMA is less interference with neighborhood channel. In our newly proposed multi-carrier CDMA data transmission method, lIR CMFB filter banks sharply divide sub-bands and reduces spectral overlaps among neighboring sub-channels. In experiment result, proposed filter is better ability of sub-band division than FIR filter. Since the proposed cosine modulated filter banks lIR filter having wavelet property is designed to response sharp transition band, the ISI and ICI between neighboring sub-channels can be effectively reduced. And robustness about narrow band interference of CMFB IIR MC-CDMA almost same FIR DWT MC-CDMA.

• Current Optics and Photonics
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• v.2 no.1
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• pp.34-38
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• 2018

An X-band microwave photonic (MWP) filter using switch-based fiber-optic delay lines has been proposed and experimentally demonstrated. It is composed of two electro-optic modulators (EOMs) and $2{\times}2$ optical MEMS-switch-based fiber-optic delay lines. By changing time-delay difference and coefficients of each wavelength signal by using fiber-optic delay lines and an electro-optic modulator, respectively, a bandpass filter or a notch filter can be implemented. For an X-band MWP filter with four channel elements, fiber-optic delay lines with the unit time-delay of 50 ps have been experimentally realized and the frequency responses corresponding to the time-delays has been measured. The measured frequency response error at center frequency and the time-delay difference error were 180 MHz at 10 GHz and 3.2 ps, respectively, when the fiber-optic delay line has the time-delay difference of 50 ps.

• Current Optics and Photonics
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• v.3 no.2
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• pp.111-118
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• 2019

The optical characteristics of a tunable flattened-pass-band fiber comb filter, based on the polarization-diversified loop configuration, are investigated using the $Poincar{\acute{e}}$-sphere representation. In the design process, the spectral flatness is checked quantitatively, and the tunability of the pass band is demonstrated experimentally. Theoretical calculations show that the filter also exhibits desirable dispersion and polarization properties. The orientation angles of rotatable wave plates for the wavelength tunability of the filter are obtained. Furthermore, we elaborate on the multiple angle loci produced by degeneracies through the combination of optical elements within the loop of the filter.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.91-97
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• 2012

This paper first proposes the speech recognition algorithm by detection of the speech and noise sections at each frame, then proposes the reduction algorithm of environmental noise by multi-band filter which removes the background noises at each frame according to detection of the speech and noise sections. The proposed algorithm reduces the background noises using filter bank sub-band domain after extracting the features from the speech data. In this experiment, experimental results of the proposed noise reduction algorithm by the multi-band filter demonstrate using the speech and noise data, at each frame. Based on measuring the spectral distortion, experiments confirm that the proposed algorithm is effective for the speech by corrupted the noise.