• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.11-18
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• 2006

A new algorithm for removing salt and pepper impulse noise in image using impulse noise detector and total variation optimization is presented. The proposed two types of noise detectors which are based on the adaptive median filter, can detect impulse noise with high accuracy while reducing the probability of detecting image details as impulses. And the detectors maintain its performance independent of noise density. For removing impulses, total variation optimization is applied only to those detected noise candidate to reduces unnecessary computation. The proposed approach successfully remove impulse noise while preserving image details.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1032-1036
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• 2006

본 연구에서는 영산강 본류를 대표하는 나주지점을 대상으로 하여, 해당 지점에서 자동 측정되고 있는 수질 항목들 중에서 총유기탄소(TOC: Total Organic Carbon)의 시계열 자료에 대한 비선형 동역학적 거동을 파악하고자 하였다. 1994년 낙동강에서의 수질오염 사고 이후 4대강 유역에서 설치.운영되고 있는 수질자동 측정망의 TOC 자료를 일자료로 환산하여 사용하였으며, 시계열 자료에 비선형 동역학적(카오스적) 특성이 존재하는지를 알아보기에 앞서 자료의 전처리 과정으로써 3가지의 잡음제거 방법을 적용하였다. 잡음이 제거된 시계열 자료에 비선형 동역학적 거동의 파악을 위해 보편적으로 사용되고 있는 상관차원분석을 실시하였다. 또한 상관차원분석 결과 비선형 동역학적 거동을 나타내는 것으로 판별된 자료에 대하여 그 양상을 가시적으로 알아보기 위해 지체시간$(\tau)$을 적용하여 3차원 위상공간에 도시하였다. 본 연구의 결과, 나주지점에서 측정되고 있는 총유기탄소에 대해 비선형 잡음제거 방법을 적용한 자료가 비선형 동역학적 거동을 내재하고 있는 것으로 나타났으나, 이를 위상공간에 재건하였을 경우 이상한 끌개(strange attractor)의 뚜렷한 구조가 보이지 않았다. 그러나 상관차원분석 결과 잡음이 제거된 자료가 카오스적 특성을 보이므로, 자료의 단기예측을 위한 방법에 기초적인 정보를 제공할 수 있을 것으로 기대된다.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.147-147
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• 2001

목적： RF 자기장이 존재하는 공간이 좁을수록 신호 대 잡음비가 증가한다. 이것을 이용하여, 기존의 표면 코일보다 RF 자기장의 공간을 좁혀서 코일 근방에서 신호 대 잡음비를 개선할 수 있는 표면 코일을 개발한다. 대상 및 방법： 기존의 표면 코일의 RF 자기장은 쌍극자(Dipole) 자기장 형태이다. 쌍극자 모드는 자기장의 세기가 1/r$^3$로 감소한다 하지만 자기장을 사중극자(Quadrupole) 형태도 발생시키면, 1/r$^{5}$ 로 감소하게 되어, 극자(pole)로부터 먼 곳에서는 자기장의 감소가 매우 급격히 일어난다. 극자 근방에서는 쌍극자와 사중극자 자기장의 세기 차이가 거의 없다. 이런 원리들을 이용하여 표면코일의 형태를 사중극자 자기장이 발생하도록 제작하여, 코일로부터 먼 곳의 신호는 코일에 검출되지 못하게 하였다. 그러므로 신호 대 잡음비에 큰 이득을 볼 수 있다.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.169-173
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• 1999

We have experimentally investigated the eye margin characteristics of intensity modulated 10Gb/s NRZ signals in optically amplified systems depending on optical signal-to-noise ratio and chromatic dispersion. For the practical system application, the minimum optical signal-to-noise ratio was 25 dB. We utilized the negative chirped transmitter and a dispersion compensation fiber to compensate the chromatic dispersion in single mode fiber. We found the optimum eye opening and receiver sensitivity in case of the residual dispersion of 0~+935 ps/nm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.86-89
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• 2015

Quantitative Evaluation of Image Quality using Automatic Exposure Control This it leads, the relationship of control and image between of photographing condition, DR proper use method proposing. Chest phantom acquires Chest PA images which it follows in conditional change, Image evaluation factor (SNR (Signal to Noise Ratio), CNR (Contrast to Noise Ratio), PSNR (Peak Signal to Ratio), RMS (Root Mean Square)). It excepted RMS price, SNR, CNR, PSNR the case which uses AEC it came out being high The fact that the quality of image is better there was a case which does not use AEC. but Price it was slight. Image qualitative it was deficient in AEC use presence. Through this, the overall situation and most efficient use of radiation workers is better suited. But Passive AEC use would be appropriate for use rather than proactive AEC.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.19-32
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• 2003

In the conventional photorefractive joint transform correlator(PRJTC), the intensity ration of input signal-to-pump beam should be large enough to saturate two-beam coupling transfer function to obtain a desired correlation result. As a result, the signal-to-noise ratio(SNR) of correlation result is decreased in a noisy input image. In this paper, we propose the improved method for increasing the SNR of the PRJTC by using the characteristics of BaTiO$_3$. We stop the energy transfer saturating by low intensity ratio of input beam and realize a short length of effective interaction in BaTiO$_3$ by making large incident angle of the signal beam. So the gain in high frequency area is decreased and the gain in low frequency area comes up to the saturation gain of the beam coupling transfer function. Therefore the SNR is improved in noisy input image and the PRJTC can be easily realized by low intensity ratio of input beam.

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.310-315
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• 2015

A single channel VAD (Voice Activity Detection) algorithm for nonstationary noise environment is proposed in this paper. Threshold values of the feature parameter for VAD decision are updated adaptively based on estimates of means and standard deviations of past non-speech frames. The feature parameter, SPD-TE (Spectral Power Difference-Teager Energy), is obtained by applying the Teager energy to the WPD (Wavelet Packet Decomposition) coefficients. It was reported previously that the SPD-TE is robust to noise as a feature for VAD. Experimental results by using TIMIT speech and NOISEX-92 noise databases show that decision accuracy of the proposed algorithm is comparable to several typical VAD algorithms including standards for SNR values ranging from 10 to -10 dB.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.47-50
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• 2000

비상관적인 가산잡음에 오염된 음성으로부터 향상된 음성을 얻기 위한 방법 중 Soft Decision에 근거한 음성 향상 기법이 뛰어난 성능을 가진다고 알려져 있다. Soft Decision은 주파수 영역에서 음성에 가산된 잡음을 처리하며, 잡음 환경에 대한 사전정보에 의존적이다. 본 연구에서는 Soft Decision을 근거로 음성에 가산된 잡음신호를 비선형 처리를 하여 효과적으로 음성에 포함된 잡음을 추정하도록 하였으며, 잡음환경에 대한 사전 정보 없이 효율적으로 잡음을 억제하는 방법을 제안한다. 본 연구에서 제안한 음성향상 기법은 주관적인 음질평가에서 기존의 방법들보다 나은 성능을 나타내었다

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.374-380
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• 2010

It is known that the problem of FIR filtering with noisy input and output data can be solved by a total least squares (TLS) estimation. It is also known that the performance of the TLS estimation is very sensitive to the ratio between the variances of the input and output noises. In this paper, we propose a convex combination algorithm between the ordinary recursive LS based TLS (RTLS) and the ordinary recursive LS (RLS). This combined algorithm is robust to the noise variance ratio and has almost the same complexity as the RTLS. Simulation results show that the proposed algorithm performs near TLS in noise variance ratio ${\gamma}{\approx}1$ and that it outperforms TLS and LS in the rage of 2 < $\gamma$ < 20. Consequently, the practical workability of the TLS method applied to noisy data has been significantly broadened.

• Journal of Biomedical Engineering Research
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• v.20 no.3
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• pp.299-305
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• 1999

In thls paper, the representative beal textraction algorIthms for the diagnostic parameter extraction in noisy signal were compared. We used the avernge, median, mode, and trmmed mean to calculale the central tendency. In our experimenl, we have restricted to four kinds of noises -EMG noise, 60Hz powerline inlerference, ahrupl baseline shift, and baselme drift due to respimtion-which were commonly occurred in ECG mgnal, then we have calculated signal-to-noise ratios(SNRs) for the ECG corrupted with each noise and all noises together. As the result of this paper, we have proved that the average method has super lor performance than the others in the ECG corrupted wilh EMG noise. When the signal mcludes extreme value such as abrupt baseline shIft, the median, mode, trimmed mean methods have supenor performance in the SNR ratios. Especially when the ECG corrupted with baseline drift due to respirallon, the trimmed mean method was most efficient because ST level change was 0 V.