• 소음진동
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• 제7권3호
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• pp.427-437
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• 1997

Mean active intensity based active control for the cancellation of radiated noise out of the duct exit is studied. The active intensity control strategy is drerived based on the relation of the exterior sound field out of the duct termination and interior sound field of the duct. One of the characteristics of this control strategy is that the control performance can be maintained regardless of the sensor loction, compared with the conventional local pressure control methods at either interior downstream or exterior field positions. It is also suggested that the digital filtering for the active intensity control can be achieved by time-domain filtered-x LMP (Lest-Mean-Product) adaptive algorithm. Experiments for an open-ended duct are performed to compare the active intensity control performance with conventional pressure control one. Active control experiment of local sound pressure is conducted by widely used filtered-x LMS adaptive Algorithm and active intensity control implementaion uses the derived filter d-x LMP algorithm. It is shown that the exterior sound fileds was much better observable by sensing of the active intensity than by just sound pressure. It is also demonstrated that the global control performance of external field by acoustic intensity is superior to the conventional sound pressure control performance.

• 한국소음진동공학회논문집
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• 제26권2호
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• pp.195-202
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• 2016

In this study, a concept of active sound enrichment (ASE) control system was implemented and demonstrated for improving engine sound quality inside the cabin of a passenger car during acceleration. Unlike the active noise control cancels the noise for disturbance rejection, the ASE adds additional sound to the noise for tracking control. This approach requires a new algorithm to provide additional artificial sound to the original engine sound using active control strategy to achieve a target sound profile, which is predefined to satisfy required interior sound quality. The ASE algorithm was implemented in a digital controller dSPACE DS1401 and real-time control experiment was accomplished in an actual car. The ASE control results show that the actively enriched sound of each engine order against RPM tracks the target profiles precisely and quickly and improves the discontinuity, the level ratios and the sound pressure level of each engine order. Thus it is anticipated the ASE system can be applied for the improvement of the engine sound quality inside the cabin during acceleration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.857-861
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• 2004

An active method that improves low frequency characteristics of a reverberation chamber has been proposed. Spatial uniformity of sound pressure at low frequency has been increased by applying active noise control system. The system acts as frequency selective damping materials, which decreases resonance at low frequency and leave high frequency sound field as it is. Linearity of the chamber, which is essential for sound power measurement in the chamber, is guaranteed since fixed control logic has been adopted. Simple application and tests have been done in a small sized rectangular reverberation chamber which has 400Hz cutoff, Loud speakers were used to simulate a noise source and to construct an active noise control system. The spatial distribution of a sound field at 250Hz, 315Hz and 400Hz bands has been measured before and after control. The standard deviation of sound field has been decreased from 3.4dB to 2.5dB. The results show the possibility of active control system as a sound diffuser.

• International Journal of Aeronautical and Space Sciences
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• 제2권2호
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• pp.19-27
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• 2001

This research attempts to find an active control strategy which reduces acoustic power and acoustic energy in lightly-damped enclosed sound field such as a vehicle compartment or an operating room of heavy industrial machinery. An active control strategy, which takes into consideration of the acoustic radiation power of the source as a cost function, is formulated and examined to find capability of reducing noise. An adaptive filtering algorithm for sound power control is suggested and implemented to control lightly-damped sound field. To verify the method, sound power based active noise control algorithm was implemented on a rectangular box with lightly-damped wall, and popular acoustic energy based control with modal coupling reduction was performed to compare the noise reduction performance. It was shown that a total sound power based strategy provides a practical mean for global noise reduction for lightly damped sound field.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.608-612
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• 2000

Active control of sound radiation(using active structural acoustic control) from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Control structural input are achieved by two piezoceramic actuators bonded to the surface of the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The control approach are based on a multi-channel filtered-x LMS algorithm. The results demonstrate that attenuation of sound levels of 3dB, 13dB are achieved.

• 한국소음진동공학회논문집
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• 제12권9호
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• pp.694-701
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• 2002

In this paper, through the study on locations of structural transducers for active control of the radiated sound from the vibrating plate, the active structural acoustic control (ASAC) system is proposed. And, for the evaluation of the proposed location, the experiment of the active structural acoustic control is implemented using the multi-channel filtered-x LMS algorithm and an additional filter (Acoustic Prediction Filter) to estimate the radiated sound using the acceleration signals of the plate. The structural transducers are piezoceramic actuator (PZT) and accelerometer. PZT is used as an actuator to reduce the vibration and the radiated sound. To maximize the control performance, each PZT actuator is located at the position that has the largest control sensitivity of the plate bending moment in the direction of x and y coordinates and the optimal PZT location is validated experimentally. Also, to find the acoustic prediction filter accurately, two accelerometers are located at the positions that have the largest radiation efficiencies of the plate, and the proposed locations are validated by simulation using the Rayleigh integral. The multi-channel filtered-x LMS algorithm is introduced to control a complex 2-D structural vibration mode. Finding the locations of structural transducers for active structural acoustic control of the radiated sound, the active structural acoustic control (ASAC) system can be presented and validated by experiments using a real time control system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.489-496
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• 2008

This paper investigates active noise control of ducts using Filtered-x Least Mean Square (FXLMS) algorithms to reduce noise transmission. Single channel FXLMS (MFXLSM) and multiple channel FXLMS (MFXLMS) algorithms are used to implement the active control systems. The transmission loss is significantly increased by SFXLMS but the sound pressure level (SPL) at the upstream of the error sensor is increased while that of downstream is very low. This increase of the upstream SPL causes the duct wall to vibrate and so to radiate noise. To prevent the wall vibration generated by the sound field upstream, global sound field control is required. To reduce SPL globally along the duct, active noise control using MFXLMS is implemented. We can then obtained globally reduced SPL. It is found experimentally that the vibration level, and so the radiated noise level. can be reduced by the active noise control using MFXLMS.

• 한국소음진동공학회논문집
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• 제19권1호
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• pp.24-34
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• 2009

This paper investigates active noise control of ducts using filtered-x least mean square(FXLMS) algorithms to reduce noise transmission. Single channel FXLMS(SFXLSM) and multiple channel FXLMS(MFXLMS) algorithms are used to implement the active control systems. The transmission loss is significantly increased by SFXLMS but the sound pressure level(SPL) at the upstream of the error sensor is increased while that of downstream is very low. This increase of the upstream SPL causes the duct wall to vibrate and so to radiate noise. To prevent the wall vibration generated by the sound field upstream, global sound field control is required. To reduce SPL globally along the duct, active noise control using MFXLMS is implemented. We can then be obtained globally reduced SPL. It is found experimentally that the vibration level, and so the radiated noise level, can be reduced by the active noise control using MFXLMS.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.955-956
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• 2014

Active noise control is noise reduction method by generate anti-phase control signal for destructive interference of through control speaker. purpose of this paper is create a virtual control source at a using the DBAP(Distance Based Amplitude Panning) algorithm which is one of the three-dimensional sound reproduction method, and verified through the experimentally for noise control method through the virtual control source. We compared active noise method by using one control speaker with active noise control method by using DBAP algorithm.

• 한국음향학회지
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• 제28권8호
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• pp.806-814
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• 2009

이 논문은 능동흡음재를 이용한 수중음향반사파 상쇄에 관한 연구이다. 능동흡음재는 평판형 구동센서와 수신센서로 몰딩되고 외부 제어기와 연결된 구조로 되어있다. 이 두 층의 센서와 피드백제어기는 하나의 피드백 루프를 이루며, 이 루프의 특징은 외부로부터 인가되는 입사파에 대해 음향 임피던스가 자동적으로 정합되어, 자동적으로 반사파를 상쇄하는 특성을 가진다. 능동흡음재의 전기 구조 음향의 다중물리특성은 1차원 전달함수로 모델링 되고, 운용주파수 대역에서 입사파에 대한 반사파가 최소화 되도록 제어기의 전달함수가 설정된다. 능동형 흡음재는 수동형 흡음재의 두께에 비하여 현저히 얇은 두께를 가지며, 간단한 아날로그 회로 제어기만으로도 넓은 주파수 대역에서 우수한 흡음특성을 보인다.