• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.49-56
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• 2022

In this study, numerical simulations for reducing noise between floors in an apartment building was carried out using Active Noise Control (ANC) technology. In order to examine the feasibility of using ANC to reduce noise between floors, accelerometers and microphones for noise collection were installed in the inter-floor noise test facility to measure noise and vibration caused by the impact ball drop test. By using the measured data, Filtered-x Least Mean Square (Fx-LMS) algorithm-based ANC simulations were carried out. In the simulations, after deriving optimal simulation conditions including the adaptive control convergence coefficient, the noise reduction effect was analyzed through numerical simulations using the number of installed accelerometers and speakers as variables. Finally, it was confirmed that the noise between floors could be reduced using ANC technology under limited conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.670-677
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• 1998

Many of the adaptive noise control systems utilize a form of the least mean square (LMS) algorithm. In the active control of noise, it is common practice to locate an error microphone far from the control source to avoid the near-field effects by evanescent waves. Such a distance between the control source and the error microphone makes a certain level of time-delay inevitable and, hence, may yield undesirable effects on the convergence properties of control algorithms such as filtered-x LMS. This paper discusses the dependence of the convergence rate on the acoustic error path in these popular algorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. Performances of the new LMS algorithms are presented in comparison with those by the conventional algorithms based on computer stimulations and experiments.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.730-733
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• 2002

In this paper, implementation of active noise barriers using active noise control techniques is presented. Multi-channel FX-LMS algorithms and Leaky LMS algorithms are used for adaptive filters to attenuate noise which is propagated from the outside of experimental enclosures. Experiments have done to show the effectivene a proposed active noise barriers.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.111-116
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• 2013

Noise problem that occurs on the road is raising a lot of problems in the economic, social and environmental aspects. The objective of this paper is to propose ANC(active noise cancellation)-based road traffic noise reduction algorithm-model which can reduce noise by generating frequency opposed to noise sources to improve and complement the problem that existing physical form of a noise barrier. In this paper, we measured the noise characteristic from collection of two difference car noise also ANC simulation has been performed by using road traffic noises input. In order to compare the control performance, we performed noise reduction simulation of ANC by filtered-X LMS algorithm and delayed control signal injection. As a result of this simulation, we confirmed that convergence performance and noise decrease effect to the filtered-X LMS algorithm by inputting the road traffic noise.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.154-160
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• 2004

In this paper, implementation of active noise curtains using multiple channel adaptive filters is presented. The same numbers of single channel LMS algorithms as control loudspeakers is used instead of a multi-channel LMS algorithm to reduce the computational burden of adaptive filter algorithms. In general, a multi-channel LMS algorithm is usually used in active noise control system. but this algorithm has much more computational complexity. The single channel control techniques have less amount of DSP calculation, compared to multiple channel control techniques. A stabilizing procedure for adaptive IIR filters is also proposed to improve the stability of recursive LMS algorithms. Both experimental results of two control techniques using TMS320VC33 digital signal processor show the similar noise reduction, but the single channel control techniques are more efficient in practical active noise curtain applications

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1078-1084
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• 2011

In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling fan is studied. An efficient temperature control scheme for the LED lamp using the fan wind at the lowest sound noise is studied. Also, for minimization study of sound noise and temperature control of an LED lamp, a sequential control algorithm using the cooling fan at the lowest sound noise is presented. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan was performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.374-379
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• 2002

A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.81-89
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• 1999

The major source of noise in the process of transporting liquids is related to the cavitation phenomenon. The control valve noise is mostly dominated by bubble dynamics under cavitating conditions. In this investigation, an orifice configuration is set-up to correlate its flow-field and acoustic signatures with those from a control valve device. The performance and noise characteristics form the orifice configuration in anechoic surroundings were measured to reveal the noise sources depending on pressure differences across the orifice configuration. The sound powers from the orifice configuration are effectively normalized using proposed scaling parameters. Flow-excited dynamic systems for which there is no strong coupling between the flow and the system response can be described using a linear source-filter model. On this assumption, the normalized sound powers can be decomposed of noise source function and a response function. To find noise sources, pressure spectra measured over a range of pressure differences are transformed into the product of two non-dimensional frequency function : $P_{ss}(He,f_{ca},x/D) = F(f_{ca})\;G(He,x/D)$. This scheme of finding noise sources is shown to be applicable to the cavitation noise from the control valve effectively Two kinds of cavitating modes based on our experimental data are found and discussed.

• Journal of the Ergonomics Society of Korea
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• v.34 no.3
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• pp.265-278
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• 2015

Objective:To study the sources of indoor noise, its effects on human health, noise assessment and regulation through the use of standards, and techniques used to reduce noise. Background: Noise significantly affects the living environment, and there are an increasing number of reports of its impacts on human health. Method: We reviewed domestic and foreign data regarding environmental noise, and examined its effects and the standards used to regulate noise levels. Results: We describe the major sources of indoor noise and suggest possible legal standards, as well as recommended criteria for the control of noise. Conclusion: South Korea has higher legal standards of environmental noise than international standards in terms of threshold values. People in Korea are exposed to various sources of noise, and therefore the reduction of noise is urgently required. Application: Depending on the features of indoor spaces, an appropriate degree of indoor noise can be determined and techniques to reduce excess noise are required.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.493-498
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• 2004

The EMI noise source in a switching mode power supply is dominated by a common mode noise. If we can understand the common mode noise occurring mechanism, it is resulted to find out the method to suppress the EMI noise source in the switching mode power supply. The common mode noise is occurring mostly due to circuit is unbalanced which is caused by the capacitive coupling to frame ground, which passes through a heatsink of the switching devices. This research paper presents a new effective balancing method of buck converter circuit by mean of grounding the parasitic and compensation capacitors in correct proportion which is called that the common mode impedance balance (CMIB). The CMIB can be achieved by source, transmission line and termination balanced, such balancing, the common mode current will be cancelled out in the frame ground. The greatly reduced common mode noise can be confirmed by the experimental results.