• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.654-656
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• 1998

This paper deal with the implementation of Active Noise Control (ANC) in a short duct. In case of ANC in the air duct, input microphone, control speaker, error microphone are used. But we can't use input microphone because of the characteristics of short duct. It is difficult to avoid howl. So we propose single-channel adaptive feedback ANC which is composed only error microphone and control speaker without input microphone. FXLMS algorithm is used to compensate for the time delay of the error path. Experimental results show that the controller reduce noise signal sufficiently.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.288-293
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• 2009

This study presents the active noise control of duct noise. The duct was excited by a steady-state harmonic and white noise force and the control was performed by one control speaker attached to surface of the duct. An adaptive controller based on filtered x LMS(FXLMS) algorithm was used and controller was defined by minimizing the square of the response of the error microphone. The assemble controller, which is called a hybrid ANC(active noise control) system, was combined with feedforward and feedback controller. The feedforward ANC attenuates primary noise that is correlated with the reference signal, while the feedback ANC cancels the narrowband components of the primary noise that are not observed by the reference sensor. Furthermore, in many ANC applications, the periodic components of noise are the most intense and the feedback ANC system has the effect of reducing the spectral peaks of the primary noise, thus easing the burden of the feedforward ANC filter.

• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.

• 전기학회논문지
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• 제62권12호
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• pp.1771-1776
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• 2013

Most cases of power transformer failure are caused by physical factors linked to the transient vibrations of multiple 120Hz combinations. In addition, the noise generated in the transformer from this vibration not only directly contributes to the worsening of the work environment but also causes psychological stress, resulting in the worsening of the workers efficiency and of the living environment of the inhabitants around the power plant. Thus, to remedy these problems, the mechanical-excitation forces working on a power transformer were categorized in this study, and the mechanical-damage mechanism was identified through the vibration transfer paths acting on machines or structures. In addition, a study on active noise cancellation in a transformer using the FXLMS algorithm was conducted to develop a system that is capable of multiple-sound/channel control, which resulted in the active noise reduction effect when applied on the field.

• 한국소음진동공학회논문집
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• 제24권1호
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• pp.62-68
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• 2014

Recently, MRI(magnetic resonance imager) scanner is continually used for medical diagnosis and many biomedical researches. When it operates, however, intense noise is generated. The SPL(sound pressure level) of the noise approaches 130 dB especially in 3 T(Tesla) MRI. Meanwhile, more than 3 T MRI scanners have been developed to get higher-resolution images, so louder noise is expected in the future. The intense noise makes patients feel nervous and uncomfortable. Moreover, it could possibly cause hearing loss to patient in extreme cases. For this reason, some active noise control systems have been researched. One of them used feedback Filtered-X LMS(FXLMS) algorithm which is able to control only narrowband noises and possible to diverge in severe case. In this paper, we determine the property of MRI noise. Using the property, we applied a method of open-loop and adaptive control for reducing MRI noise at target point inside bore. We verified performance of the method with computer simulation and preliminary experiment. The results demonstrate that the method can effectively reduce MRI noise at target point.

• 대한전자공학회논문지TE
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• 제42권4호
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• pp.41-46
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• 2005

현대사회에서 소음과 진동은 일상생활뿐 아니라 산업현장에서도 흔히 접하게 되는 환경오염원으로, 이에 대한 관심이 점차 증가하고 있다. 산업현장에서 소음은 중요한 안전요소의 하나이며, 근로자의 청력에 영향을 미칠 뿐 아니라 정신적으로도 많은 영향을 미쳐 최종적으로 업무효율을 떨어뜨리게 되는 중요한 원인이 된다. PCB 산업 현장에서는 제조공정상 필요한 기계들로부터 다양한 소음들이 발생된다. PCB 산업현장의 소음원은 주로 공조기와 제조 기기에서 발생되며, 발생된 소음제어를 위해서는 소음의 전달경로를 막아 소음을 줄이는 방법과 제조기기의 소음을 저감시키는 방법, 수음자에 대한 제어방법 등이 있다. 본 논문에서는 PCB 산업현장에 쉽게 적용할 수 있는 헤드셋(headset)을 이용한 부대역 feedback 능동소음제어(subband feedback active noise control) 방법에 인간의 청각기능을 모델링한 멜 척도를 적용하여 보다 효과적인 소음제어 방법을 제안하였다. 실험결과 멜 척도를 적용하지 않은 부대역 feedback 능동소음제어방법 보다 동일한 구조를 가지면서도 빠른 수렴속도와 향상된 소음제거 결과를 얻을 수 있었다.