• 한국전자파학회논문지
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• 제27권1호
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• pp.1-7
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• 2016

본 논문에서는 기계식 스위치를 이용한 1.5 GHz 대역 고출력 Cavity 기반 튜너블 필터를 설계하고 제작하였다. 불요파를 제거하기 위해 저역통과필터를 삽입하고, 출력을 추출하기 위해 Coupler를 내장하였으며, 고출력에 적합한 기계식 스위치를 사용하여 튜너블 필터의 시스템을 구성하였다. 저역통과필터는 4~12.75 GHz까지 40 dB 이상의 감쇄 특성을 얻었고, Coupler는 40 dB의 Coupling Value와 55 dB 이상의 Coupling Isolation을 얻었다. 제작된 기계식 스위치를 사용한 튜너블 필터 시스템은 1,495.9~1,510.9 MHz Bypass Mode에서 0.88 dB, 1,495.9~1,500.9 MHz Fil Mode에서 3.29 dB의 삽입손실 특성 및 중심주파수 1,498.4 MHz에서 132 W의 출력전력과 10 ms 이하의 스위칭 절환속도를 얻었다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.268-271
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• 2003

There are several methods for the design of 2D filter. Notable among them is McClellan transform method. This transform allows us to obtain a high order 2D FIR filter through mapping the 1D frequency points of a 1D prototype FIR filter onto 2D frequency contours. We design 2D filter using this transform. Then we notice for mapping deviation of the 2D filter. In this paper, Quadratic programming (QP) method allows us to obtain coefficients of McClellan transform. Then we compare deviation of QP method with least-squares(LS) method. Elliptic filter is used for comparison. The optimal cutoff frequencies of a 1D filter are obtained directly from the QP method. Also several problem of LS method are solved.

• 마이크로전자및패키징학회지
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• 제9권1호
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• pp.1-7
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• 2002

본 연구에서는 이동통신 시스템의 키부품으로 필수적인 멀티미디어용 고주파 Active Filter 및 초소형 설계기술(SMD타입)을 개발하였으며, 멀티미디어 고주파 능동필터의 카오프 주파수는 2.5 mHz, 이득은100 kHz에서 0.5d B, 통과대역 리플은 100 kHz에서 2 MHz까지 최고1.2dB, GDT는 100 kHz에서 2.0 MHz까지 최고 60 nsec이며, 감쇄는 3.7 MHz에서 최소 40dB임.

• 한국물환경학회지
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• 제22권2호
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• pp.222-229
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• 2006

The treatment performance and operational parameters of a tertiary wastewater treatment process a biological filtration system were investigated. The biological filtration system consisted of a nitrification filter (Fiter 1) and a polishing filter with anoxic and aerobic parts (Filter 2). SS, T-C-BOD, and T-N in effluent were kept stable at less than 3, 5 mg/L, and 5 mgN/L, respectively, under a HRT in Filter (filter-bed) of 0.37~2.3 h. T-N at the outlet of Filter 2 were about 1~5 mgN/L under the condition of LV of 50~202 m/d. In Filter 2, denitrification was accomplished under LV of 50~168 m/d in a 1 m filter-bed. However, the denitrification capacity reached the maximum when the linear velocity was increased to 202 m/d. Relationship between increase in microorganism and headloss was clearer in Filter 2. As a result, the denitrification rate increased from 1.0~2.3 kgN/($m^3-filter-bed{\cdot}d$) as the headloss increased. The COD removal rate was 6.0~9.6 kgCOD/($m^3-filter-bed{\cdot}d$) when operated with Filters 1 and 2. These results mean that captured bacteria contributed a part of COD consumption and denitrification. The maximum nitrification and denitrification rate was 0.5 and 4 kgN/($m^3-filter-bed{\cdot}d$) in Filter 1 and 2.The ratio of backwashing water to the treated water was about 5~10 %. In Filter 1, wasted sludge in backwashing was only 0.7~5.3 gSS/($m^3$-treated water). In Filter 2, added methanol was converted into sludge and its value was 8.0~24 gSS/($m^3$-treated water). These results proved that this process is both convenient to install as tertiary treatment and cost effective to build and operate.

• 한국음향학회지
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• 제38권1호
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• pp.39-46
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• 2019

본 논문에서는 합성곱 신경망(Convolutional Neural Network, CNN) 구조를 이용하여 잡음 환경에서 음향신호를 분류할 때, 인식률을 높이는 결합 특징을 제안한다. 반면, Wiener filter를 이용한 강인한 log Mel-filter bank와 PNCCs(Power Normalized Cepstral Coefficients)는 CNN 구조의 입력으로 사용되는 2차원 특징을 형성하기 위해 추출됐다. 자연환경에서 43종의 조류 울음소리를 포함한 ebird 데이터베이스는 분류 실험을 위해 사용됐다. 잡음 환경에서 결합 특징의 성능을 평가하기 위해 ebird 데이터베이스를 3종류의 잡음을 이용하여 4개의 다른 SNR (Signal to Noise Ratio)(20 dB, 10 dB, 5 dB, 0 dB)로 합성했다. 결합 특징은 Wiener filter를 적용한 log-Mel filter bank, 적용하지 않은 log-Mel filter bank, 그리고 PNCC와 성능을 비교했다. 결합 특징은 잡음이 없는 환경에서 1.34 % 인식률 향상으로 다른 특징에 비해 높은 성능을 보였다. 추가적으로, 4단계 SNR의 잡음 환경에서 인식률은 shop 잡음 환경과 schoolyard 잡음 환경에서 각각 1.06 %, 0.65 % 향상했다.

• ETRI Journal
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• 제33권2호
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• pp.169-175
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• 2011

This paper presents a double-sharpened decimation filter based on the application of a Kaiser and Hamming sharpening technique for multistandard wireless systems. The proposed double-sharpened decimation filter uses a pre-droop compensator which improves the passband response of a conventional cascaded integrator-comb filter so that it provides an efficient sharpening performance at half-speed with comparison to conventional sharpened filters. In this paper, the passband droop characteristics with compensation provides -1.6 dB for 1.25 MHz, -1.4 dB for 2.5 MHz, -1.3 dB for 5 MHz, and -1.0 dB for 10 MHz bandwidths, respectively. These results demonstrate that the proposed double-sharpened decimation filter is suitable for multistandard wireless applications.

• 한국ITS학회 논문지
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• 제10권3호
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• pp.74-78
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• 2011

본 논문에서는 래디얼 스터브를 이용하여 이중 모드 공진기를 구현하여 이를 통하여 5.8 GHz ITS 시스템에 응용 가능한 대역 통과 필터를 제안하였다. 이중 모드 공진기를 구성하는 개방형 스터브를 래디얼 스터브로 대체함으로써 이중 모드 공진기의 크기는 약 39.6% 감소하였고 두 개의 $60^{\circ}$ 래디얼 스터브를 통해 약 $6.9{\Omega}$의 낮은 임피던스를 갖는 스터브가 구현되어 이중 모드 공진기를 이용한 필터의 저지 대역 특성이 19.4 dB에서 29.1 dB로 개선되었다. 제안된 이중 모드 공진기를 이용하여 제작된 필터는 중심 주파수 5.72 GHz에서 4.1%의 대역폭을 가졌으며, 1.79 dB와 19.4 dB의 삽입 손실과 반사 손실 특성을 나타내었다.

• 대한음성학회지:말소리
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• 제67호
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• pp.195-216
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• 2008

This paper addresses the problem of single-channel speech separation to extract the speech signal uttered by the speaker of interest from a mixture of speech signals. We propose to apply time-frequency smoothing to the existing statistical single-channel speech separation algorithms: The soft mask and the minimum-mean-square-error (MMSE) algorithms. In the proposed method, we use the two smoothing later. One is the uniform mask filter whose filter length is uniform at the time-Sequency domain, and the other is the met-scale filter whose filter length is met-scaled at the time domain. In our speech separation experiments, the uniform mask filter improves speaker-to-interference ratio (SIR) by 2.1dB and 1dB for the soft mask algorithm and the MMSE algorithm, respectively, whereas the mel-scale filter achieves 1.1dB and 0.8dB for the same algorithms.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.168-175
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• 2013

This paper presents compact dual-band WLAN filter and filter module. They were developed by embedding all of the passive lumped elements into a LTCC substrate. In order to reduce the size/volume of the filter and avoid EM parasitic couplings between the passive elements, the proposed filter was designed using a 3rd order Chebyshev circuit topology and J-inverter transformation technology. The 3rd order Chebyshev bandpass filter was firstly designed for the band-selection of the 802.11b and was then transformed using finite transmission zeros technologies. Finally, the dual-band filter was realized by adding two notch resonators to the 802.11b filter circuit for the band-selection of the 802.11a/g. The maximum insertion losses in the lower and higher passbands were better than 2.0 and 1.3 dB with minimum return losses of 15 and 14 dB, respectively. Furthermore, the filter was integrated with a diplexer to clearly split the signals between 2 and 5 GHz. The maximum insertion and minimum return losses of the fabricated module were 2.2 and 14 dB at 2.4 - 2.5 GHz, and 1.6 and 19 dB at 5.15 - 5.85 GHz, respectively. The overall volume of the fabricated filter was $2.7{\times}2.3{\times}0.59mm^3$.

• Journal of Information Display
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• 제11권1호
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• pp.24-27
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• 2010

A novel stereo 3D LCD for passive interference filter glasses is presented. A demonstrator based on a standard 120Hz LCD was set up. Stereoscopic image separation was realized in a time-sequential mode using a LED-based scanning backlight with two complementary spectra. A stereo brightness of 3 cd/$m^2$ and a channel separation of 30:1 were achieved.