• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.45-50
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• 2015

In this paper, we confirm the effective adaptive algorithm for tha active noise contorl (ANC) though the performance comparison between adaptive algorithms. Generally, the normalized least mean square (NLMS) algorithm has been widely used for an adaptive algorithm thanks to its simplicity and having a fast convergence speed. However, the convergence performance of the NLMS algorithms is often deteriorated by colored input signals. To overcome this problem, the affine pojection (AP) algorithm that updates the weight vector based on a number of recent input vectors can be used for allowing a higher convergence speed than the NLMS algorithm, but it is computationally complex. Thus, the proper algorithm were determined by the comparison between NLMS and AP algorithms regarding as the convergence performance and complexity. Simulation results confirmed that the noise reduction performance of NLMS algorithm was comparable to AP algorithm with low complexity. Therefore the NLMS algorithm is more effective for ANC system.

• Korean Journal of Construction Engineering and Management
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• v.15 no.2
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• pp.12-22
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• 2014

Recently, many people have been damaged seriously by construction noise. Accordingly, there have been increased the complaints and disputes. These complaints should be controlled strictly. Otherwise there could be delays or stops of project and losses of time and money. For this reasons, the Korean government is trying to convert from depending on the soundproof wall to noise control system focusing on noise sources. However, it is difficult to control the noise which is generated from construction site because construction equipment has very high noise level and construction noise generates temporarily and irregularly. Also, people do not know how much low frequency affect human body adversely because they cannot perceive low frequency noise easily. Hence, recently developed countries have conducted the research on the low frequency noise which damages on human physically and mentally. However, passive noise control is insufficient to reduce the low frequency noise, but only efficient to lower the high frequency noise. Thus, an approach which can complement limitations of passive noise control is needed. Therefore, the purpose of this research is to suggest the noise management model using active noise control on construction site. Also, ANC simulation has been conducted to examine its applicability on construction equipment. As a result, it is expected that there will be a reduction of construction noise and demages, as well as both mental and physical damages.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.18-24
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• 1998

선박내의 작업 환경에서 발생하는 소음은 엔진, 발전기, 펌프와 같은 다양한 소음원 에 기인하다. 이들은 대체적으로 저주파 대역에서 주기성을 가지며, 이로 인해 능동 소음 제 어 기법이 적용될 수 있다. 이 논문에서는 선박내 소음 환경을 개선하기 위해 소음 흡음 재·차단재를 이용한 헤드폰 착용과 같은 수동적인 방법이 아니라, 작업 상황에 따라 소음 을 줄이기 위한 능동소음제어(ANC: Active Noise Control) 시스템을 구현한다. 특히 선박내 의 침실 공간으로 적용 가능성을 컴퓨터 시뮬레이션을 통해 고찰하고, TMS320C50 DSP를 포함한 하드웨어 구성을 통해 그 성능을 실험하고 평가한다.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.982-984
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• 1999

For active noise control system, one would choose one of two methods: Fixed control design and Adaptive filter design. Each one has its own advantages. But fixed controller design method prefer for active noise control in a small cavity system. In this paper, we design a controller for the small cavity system using CDM and compare controller using CDM with $H{\infty}$. The order of the resulting controller is lower than that of the robust $H{\infty}$ design, which means CDM will be more prefer for implementation purpose designs.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.3
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• pp.130-135
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• 2006

There have been experiments dealing with the possibility of the actualization of the ANC system by means of operating the DSP adaptation filter. This filter is composed of various filters(including X-LMS algorithm, Filter-U algorithm, and Full-Feedback-Filter-U algorithm) that use ventilation fans and loudspeakers as a primary source in a circular duct as an experimental device. In this operation, the ANC system using the X - LMS algorithm was found to be more effective in reducing noise than without such system. When applying the input signal of the DSP board Full Feedback-Filtered-U algorithm system while having in mind that the additionally installed second control signal was gone through feedback and mixed into the detection microphone installed near the ventilation fan when using the first ventilation fan, the system was not emitted, but maintained stable during the operation of the control filter. At this point, noise tended to decrease at a maximum of l0dB compared to other algorithms at the frequency band of 170-250Hz.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.427-435
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• 2011

This paper deals with the measurement and analysis of the squeal noise according to the curvature of rail. The squeal noise is generated by the friction between the railway with curve and the wheel. The squeal noise is a big problem in Busan Metro Line 3. If the developing panel type ANC(Active Noise Control) system which is attached to the floor can reduce 5 dB in below 500 Hz, the sound pressure level of the whole band pass can be reduced about 4-4.8 dB in squeal noise above the curvature of R400. Curve squeal noise is the intense high frequency tonal that can occur when a railway vehicle transverses a curve. The frequency range is from around 500 to almost 20,000 Hz, with noise levels up to about 15 dB in curve.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.55-57
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• 1996

This paper presents an implementation of the adaptive ANC (Active Noise Control) system improving robustness. The system using the proposed algorithm shows a good performance of control, when the adaptive filter well does not work. We construct a real duct system and use DSP chip for experiment. Experimental results of the proposed algorithm prove the system to be superior than the conventional filtered-x LMS algorithm when the adaptive filter is out of order.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.993-995
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• 1996

This paper proposes an adaptive Filtered-X LMS algorithm with robustness. The proposed system updates filter parameters to keep the performance even if the conventional Active Noise Control (ANC) system well does not work. As a result of the computer simulation, the proposed system has all the advantage of the system using the conventional Filtered-X LMS algorithm. Also some results from the proposed algorithm present that the system is stable when the Adaptive filter does not work. Therefore, the proposed system using the Adaptive Filtered-X LMS algorithm must have much advantage than the system using the conventional algorithm in the side of the stability and performance.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.57-65
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• 2017

This paper presented a method of designing low-power feedback active noise control filter optimized for headphones/earphones. Using constrained optimization, we obtained a high order FIR noise control filter to ensure reasonable noise attenuation performance at high sampling frequency environment. Then using infinite impulse response (IIR) approximation method called Balanced Model Truncation (BMT), we obtained a low order IIR noise control filter suitable for low-power digital signal processing system like headphones/earphones. For further performance improvement, we utilized frequency warping method so that we could obtain more accurately approximated IIR filter and we ensured system stability by reconstructing the low order IIR filter in form of cascaded second order IIR filters. ANC simulation with white noise and stability test verified that the proposed algorithm had superior attenuation performance and better robustness compared to the conventional algorithm.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.48-55
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• 1998

The main drawback of filtered-X LMS(FXLMS) algorithm for the ANC of broadband noises is its low convergence speed when the filtered reference signals are strongly correlated, producing a large eigenvalue ratio in correlation matrix. This correlation can be caused either by autocorrelation of the signals of the reference sensors, or by coupling between the error path which introduces intercorrelation in the filtered reference signals. In this paper, we introduce a transform domain FXLMS(TD-FXLMS) algorithm that has a high convergence speed by orthogonal transform's decorrelation properties.