• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.332-335
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• 1997

In the industrial motor drive system, a shift torsional vibration si often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, the state feedback controller of the two-mass resonant system using the H$\infty$ filter is proposed. The H$\infty$ filter is robust in noise and disturbance. Simulation results show the validity proposed controller.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.96-99
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• 1984

In this study, the underwater acoustic images were obtained by ultrasonicwave. The experiment was performed in the anechoic watertank, using a passive sonar array for one and two sound source respectively by X-Y scanning technique. The receiving array was consist of 8 disc type transducers with 1.5cm diameter at 25KHz resonance frequency. The scanned data were processed by the FORTRAN IV algorithm for the reconstruction of image, and the image had some noise due to the surface reflected waves. As the result, it was found that the acoustic imaging by electrical deflection and dynamic focusing technique is applicable to SONAR with the suppression of surface reflected wave.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1619-1621
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• 1987

In this experiment, we have the result that the speech interval can be extracted with a energy parameter by noise suppression through nonlinear product average in edge enhancement method.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.241-241
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• 2013

PLS-II 저장링 진공시스템은 2011년 6월 설치 완료 후 2011년 7월부터 2012년 초 까지 1차 시운전을 마쳤다. PLS-II 저장링 진공시스템은 누적 전류 50 Ah 운전 후, 3 GeV, 400 mA 전자빔 운전 시 평균 진공도 $2{\times}10^{-9}$ mbar를 유지도록 설계되어 빔-기체 산란 수명을 20 시간 이상 확보하도록 설계하였다. 지금까지의 간략한 운전 이력과 진공시스템의 성능을 보고하고 최근 방사광 가속기에서 중요하게 취급하는 진공용기(특히, 빔전류 측정 진공용기)의 기계적 안정도, 변위 등과 BPM TE mode noise suppression 등을 보고하고자 한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.53-55
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• 2014

본 논문에서는 deconvolution 알고리즘 중에 하나인 Richardson-Lucy deconvolution 의 개선된 알고리즘을 제시한다. Richardson-Lucy deconvolution 의 단점인 반복횟수가 증가할수록 노이즈도 같이 증폭되는 현상을 소개하고 이를 개선하기 위해 기존 알고리즘에 전, 후처리 필터를 이용하여 노이즈 증폭을 억제한다. 또한 다른 노이즈 증폭을 억제하는 알고리즘과 제안된 알고리즘의 비교를 통해서 제안된 알고리즘의 성능을 보여준다.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.63-69
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• 2003

Filtering is necessary to reduce statistical noise and to increase image quality in SPECT images. Noises controled by low-pass filter designed to suppress high spatial frequency in SPECT image. Most SPECT filter function control the degree of high frequency supression by chosing a cut of frequency. The location of cut off frequency determines the affect image noise and spatial resolution. If select the low cut off frequency, its provide good noise suppression but insufficient image quantity and high cut off frequencies increase the image resolution but insufficient noise suppression. The purpose of this study was to determines the optimam cut off level with comparison of FWHM according to cut off level in each kiters-Band-limited, Sheep-logan, Sheep-logan Hanning, Generalized Hamming, Low pass cosine, Parazen and Butterworth filter in SPECT camera. We recorded image along the X, Y, Z-axis with $^{99m}TcO_4$ point source and measured FWHM by use profile curve. We find averaged length is $9.16\;mm{\sim}18.14\;mm$ of FWHM in X, Y, and Z-axis, and Band-limited and Generalized Hamming filters measures 9.16 mm at 0.7 cycle/pixel cut off frequency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.5
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• pp.348-356
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• 2003

Active vibration control algorithms for the compensator and proto-type testing system have been developed for the suppression of vibrations from the reciprocating engines. At first, the developed algorithm determines optimal control vibration phases by detecting vibration responses of the engine without and with compensator, and then performs the continuous optimal control functions by tracking the change of the vibration frequency and phase. This algorithm is comparatively simple. robust for the external excitations and needless of supplementary operation since the control process is serially carried out. To validate the performance of compensator and algorithm, testing system including excitation device are constructed and tested, and the reductions of vibration levels are observed over than 80 % of the uncontrolled levels at various frequency ranges.

• ETRI Journal
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• v.27 no.3
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• pp.334-336
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• 2005

We improved the performance of the spectrum-sliced light source for wavelength-division-multiplexed passive optical networks by employing a Fabry-Perot laser diode(FP-LD). We found that the FP-LDs can suppress the intensity noise as significantly as using a gain-saturated semiconductor optical amplifier. The transmission characteristics were measured and analyzed in both conditions with and without employing an FP-LD.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.623-628
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• 2008

We present a new method of extracting foreground object from background image for vision-based game interface. Background Subtraction is an important preprocessing step for extracting the features of tracking objects. The image is divided into the cells where the Local Histogram with Gaussian kernel is computed and compared with the corresponding one using Bhattacharyya distance measure. The histogram-based method is partially robust against illumination change, noise and small moving objects in background. We propose a Multi-Scaled Integral Histogram approach for noise suppression and fast computation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.130-135
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• 1996

This paper presents a proof-concept investigation on the active vibration control of two hybrid smart structures (HSSs). The first one is consisting of a piezoelectric film (PF) actuator and an electro-rheological fluid(ERF) actuator, and the other is featured by a piezoceramic (PZT) actuator and a shape memory alloy (SMA) actuator. For the PF/ERF hybrid smart structure, both the increment of the damping ratios and the suppression of the tip deflections are evaluated in order to demonstrate control effectiveness of the PF actuator and ERF actuator and the hybrid actuation. For the PZT/SMA hybrid smart structure, the PZT actuator takes account of the high frequency excitation, while the SMA actuator exerts large vibration control force. The experimental results exhibit superior abilities of the hybrid actuation systems to tailor elastodynamic responses of the HSS rather than a single class of actuation system alone.