• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.539-546
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• 2007

Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.11-20
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• 1997

The passive noise control techniques used until now cancel the noise in terms of the characteristics of materials, which increase the mass and the dimension and have a limit that is effective only to attenuate the high frequency components of the noise. But the active noise control techniques developed in recent years have merits that they decrease the mass and the dimension and are effective to attenuating the low frequency noises. In this paper, the real-time active noise control system attenuating the engine booming noise in a car using the digital signal processing(DSP) techniques in terms of the principle of active noise control. The multiple-error filtered-x LMS(Least-Mean Square) algorithm is used as the adaptive algorithm for active noise control and is implemented using the DSP processor Motorola DSP56001 as a controller. According to the result that the experiments are performed for the engine as the RPM changes in a car, the noise attenuating performances are achieved in an overall car interior and is verified to be 20 dB higher for pure-tone and globally, 15 dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8C
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• pp.516-521
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• 2011

In this paper, a nonlinear algorithm that maximizes zero-error probability (MZEP) with decision feedback (DF) is proposed to counteract both of severely distorted multi-path fading effect and impulsive noise. The proposed MZEP-DF algorithm has shown the immunity to impulsive noise and the ability of the feedback filter section to cancel the remaining intersymbol interference as well. Compared with the linear MZEP algorithm, it yields above 10 dB enhancement of steady state MSE performance in severely distorted multipath fading channels with impulse noise where the least mean square (LMS) algorithm does not converge below -3dB of MSE.

• Journal of electromagnetic engineering and science
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• v.7 no.2
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• pp.91-95
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• 2007

In this paper, a new linearization method has been proposed for a CMOS low noise amplifier(LNA) using the Post IM3 Compensator. The fundamental operating theory of the proposed method is to cancel the IM3 components of the LNA output signal by generating another IM3 components, which are out-phase with respect to that of the LNA, from the Post IM3 Compensator. A single stage common-source LNA has been designed to verify the linearity improvement of the proposed method through $0.13{\mu}m$ RF CMOS process for WiBro system. The designed LNA achieves +7.8 dBm of input-referred 3^{rd}$-order intercept point (IIP3) with 13.2 dB of Power Gain, 1.3 dB of noise figure and 5.7mA @1.5V power consumption. IIP3 is compared with a conventional single stage common-source LNA, and it shows IIP3 is increased by +12.5 dB without degrading other features such as gain and noise figure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.96-102
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• 2010

This paper proposes a new adaptive algorithm to cancel the acoustic feedback and noise signals in the digital hearing aids. The proposed algorithm improves its convergence performances by canceling the speech signal from the residual signal using two microphones. The feedback canceller firstly cancels the feedback signal among the mic signal, and then it is reduced the noise using the beamforming method. To verify the performances of the proposed algorithm, the simulations were carried out for some cases. As the results of simulations, it was proved that the feedback canceller and the noise canceller advance about 14.43 dB for SFR, 10.19 dB for SNR respectively during speech, in the case of using the new algorithm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.90-96
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• 2008

This paper presents an algorithm of a single chip acoustic speech enhancement for telematics device. The algorithm consists of two stages, i.e. noise reduction and echo cancellation. An adaptive filter based on cross spectral estimation is used to cancel echo. The external background noise is eliminated and the clear speech is estimated by using MMSE log-spectral magnitude estimation. To be suitable for use in consumer electronics, we also design a low cost, high speed and flexible hardware architecture. The performance of the proposed speech enhancement algorithms were measured both by the signal-to-noise ratio(SNR) and recognition accuracy of an automatic speech recognition(ASR) and yields better results compared with the conventional methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1635-1641
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• 2021

Portable systems with built-in active noise control is required low power operation. Excessive anti noise search operation can lead to rapid battery consumption. A method that can adaptively cancel noise according to the operating conditions of the system is required and the methods of reducing power are becoming very important key feature in today's portable systems. In this paper, we propose the method of active noise control(ANC) using binary search algorithm in noisy systems. The implemented architecture detects a frequency component considered as noise from the input signal and by using the binary search algorithm, the system find out an appropriate amplitude value for anti-noise in a much faster time than the general linear search algorithm. Through the experimental results, it was confirmed that the proposed algorithm performs a successful functional operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.152-160
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• 2008

In this paper, we analyze the performance of a direct-conversion UHF RFID reader with the range correlation effects of the phase noise. Since a UHF RFIB system uses the same oscillator to generate the transmitted carrier and the local oscillation, the periodic interference and phase noise reduction effects occur due to time delay between two signals. Through exact theory and simulation, we verify how to cancel the periodic interference phenomena using I/Q diversity combining technique. And, we analyze phase noise reduction effects due to range correlation as a function of the tag-reader distance and the offset frequency Using these results, we simulate the symbol-error-rate performance with respect to phase noise with and without range correation effects. We show that the phase noise of the local oscillator has little effect on the symbol-error-rate performance because of phase noise reduction by range correlation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1683-1689
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• 1999

We have implemented Frequency bandwidth expander with frequency upconverting by VCO drift canceller and comb generator. Te output of the low frequency synthesizer which the output frequency is 220~280MHz(Resolution : 5MHz) is expanded to 1660~2140MHz by this system. The phase noise of this system only depends on the phase noise of comb generator and low frequency synthesizer. The phase noise of VCO don’t influence at the frequency expander because the drift of VCO cancel out. When we control the output of VCO, the output frequency of this system is varied by 60MHz x N as filter banker. The switching time and the spurious of the frequency expander is below 3usec, -55dBc respectively. This system easily expands bandwidth additively by expanding the output bandwidth of the VCO. We can apply the frequency expander to very wide band microwave synthesizer which has fast switching time.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.5
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• pp.545-557
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• 2021

Engine is the main source of vibration that generates unwanted noise and vibration of vehicle chassis. Especially, in submarine applications, radiation of noise signatures can be detected at some distance away from the submarine using a sonar array. Thus quiet operation is crucial for submarine's survivability. This study addresses reduction of the force transmissibility originating from engines and transmitted to hull through engine mounts. An inertial damper, as an actuator of hybrid mount system, is addressed to reduce even further the level of vibration. Narrow band FxLMS algorithms are broadly used to cancel the vibration of engine mount because of its excellent performance of canceling narrow band noise. However, in real active dampers, the maximum displacement of damper mass is kinematically restricted. When the control input signal from the FxLMS algorithm exceeds this limitation, the damper mass will collide with the mechanical stops and results in many problems. Originated from these, a modified narrow band FxLMS algorithm based on the equalizer technique with the maximum allowable displacement of active damper mass is proposed in this study. Some simulation results showed that the propose algorithm is effective to suppress vibration of engine mount while ensuring given displacement constraint.