• Journal of Digital Contents Society
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• v.18 no.1
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• pp.175-182
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• 2017

Noises are usually generated by various external causes and low quality devices in image data acquisition and recording as well as by channel interference in image transmission. Since these noise signals result in the loss of information, subsequent image processing is subject to the corruption of the original image. In general, image processing is performed in the mixed noise environment where common types of noise, known to be Gaussian and impulse, are present. This study proposes an iterative weighted mean filter for reducing mixed type of noise. Impulse noise pixels are first turned off in the input image, then $3{\times}3$ sliding window regions are processed by replacing center pixel with the result of weighted mean mask operation. This filtering processes are iterated until all the impulse noise pixels are replaced. Applied to images corrupted by Gaussian noise with ${\sigma}=10$ and different levels of impulse noise, the proposed filtering method improved the PSNR by up to 12.98 dB, 1.97 dB, 1.97 dB respectively, compared to SAWF, AWMF, MMF when impulse noise desities are less than 60%.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.1
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• pp.87-94
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• 2009

Noise estimation and suppression are a crucial factor of many speech communication and recognition systems. In this paper, proposed algorithm is based on the ratio of variance normalized of noisy power spectrum in time-frequency domain. Our proposed algorithm tracks the threshold and controls the trade-off between residual noise and distortion. This algorithm is evaluated by the ITU-T P.835 signal distortion (SIG) and segment signal to noise ratio (SNR), and is superior to the conventional methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.152-160
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• 2013

In this paper, to the aim of wideband SSN(Simultaneous Switching Noise) suppression characteristic, investigation of spiral resonator are used in conjunction with bead which is commonly used for noise suppression method. Bead works effectively to suppress the power noise up to the first harmonic of fundamental frequency, 0.8 GHz, and spiral resonator suppress noise well in the frequency range of SRF(Self Resonance Frequency) which is inversely proportional to the length of spiral. Thus, when bead used in conjunction with a spiral the noise suppression characteristic is determined by the one of higher impedance element of the two in the frequency range and achieves more broadband filtering characteristic. The case for using 22 nH bead turns out 4.8, 2.0, 0, and, 0.6 dB, and the case for using 22 nH bead in conjunction with 3-turns spiral achieves more wideband characteristic of 9.5, 8.3, 6.1, and 9.9 dB power noise suppression performances at the first, second, third, and fourth harmonics, respectively. The peak-to-peak voltage levels decrease from 76 mV to 56 mV using 22 nH bead, and the level decrease rapidly to 34 mV when using in conjunction with bead and 3-turn spiral. Thus more wideband SSN suppression characteristic can be achieved using bead with spiral.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.351-355
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• 1996

유연한 보의 진동문제에 대해 Filtered-X LMS 알고리즘을 이용하여 제어계를 구성하고 디지탈 신호처리보드를 이용하 여 실시간 제어를 수행하였다. 제어 엑추에이터로는 피에조 세라믹을 사용하였고 정현파 및 백색잡음 형태의 외력으 로 Shaker를 이용하여 보를 가진하였다. 백색잡음가진 실험결과 1차 고유진동수에서 14dB의 진동저감을 할 수 있었 으며 관심 주파수영역내에서진동이 고르게 저감되었다.

• Electric Engineers Magazine
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• s.159
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• pp.20-31
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• 1995

• Electric Engineers Magazine
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• s.158
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• pp.17-23
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• 1995

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.583-591
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• 2008

OFDM (orthogonal frequency division multiplexing) has serious problem of high PAPR (peak-to-average power ratio). Recently, CI/OFDM (carrier interferometry OFDM) system has been proposed for the low PAPR. However, CI/OFDM system shows another problem of ICI because of phase offset mismatch due to the phase noise. In this paper, to simultaneously reduce the PAPR and ICI effects, we propose an A-CI/OFDM (advanced-CT/OFDM). This method improves the BER performance by use of the margin of phase offset at CI codes. Propose system to reduce the effect the phase noise, even though it shows a little bit higher PAPR than conventional CI/OFDM, so we apply the PTS among the PAPR reduction techniques to proposed system to mitigate this problem. Therefore, it improves the total BER performance because the proposed method can decrease the effect of phase noise and get the gain in PAPR reduction performance. From the simulation results, we can show the performance comparison between the conventional OFDM, CI/OFDM and A-CI/OFDM.

• Electronics and Telecommunications Trends
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• v.16 no.1 s.67
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• pp.56-70
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• 2001

마이크로파대 이상의 높은 RF 전파는 신호레벨이 비교적 작고 간섭현상에 매우 민감한 특성을 가지고 있다. 따라서 이러한 미소한 입력전파의 수신시 수신기 전체의 감도를 높이고 잡음을 저감시킬 목적으로 사용되는 고주파 증폭기가 저잡음 증폭기이다. 본 고에서는 LNA의 기본적 특성분석과 지능형교통시스템에 응용되는 5.8GHz대 단거리전용통신용 LNA를 구현하기 위한 기본 FET 증폭기의 전기적 특성을 연구하고 직렬 궤환에 의한 최소잡음과 최소 입력 정재파비의 최적 설계 파라미터를 도출하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1412-1413
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• 2008

본 연구에서는 산업용 거리 계측기에서 정밀한 측정에 요구되는 오차 보정 기법을 제시하였다. 제시한 기법은 본 연구에서는 산업용 거리 계측기에서 보다 정밀한 측정을 위한 방법으로 측정하고자 하는 기법을 전원회로에서의 잡음, 공급 전원의 잡음, 공통모드에서의 잡음, 중간주파수에 섞여 있는 잡음 및 비교기에서의 오차 저감 기법을 제시하고자 한다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.6
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• pp.63-70
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• 1994

컴퓨터나 정밀기기기의 빈번한 운용으로 배전선 반송통신 시스템의 신뢰도는 그 어느 때보다 크게 요구된다. 배전선에 나타나는 여러 종류의 잡음은 반송통신 정보를 쉽게 오염시켜 전체 시스템에 큰 영향을 미치게 된다. 본 논문에서는 평활 잡음과 60[Hz] 전원 주파수에 동기된 고조파 잡음제거를 위해 LMS와 NLMS알고리즘을 이용한 적응필터를 사용하였고 컴퓨터 시뮬레이션을 수행해 본 결과 신호 대 잡음비의 관점에서 LMS보다 NLMS의 탁월한 효과를 확인하였다.