• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.5
• /
• pp.99-106
• /
• 2006

In this paper, implementation of active mufflers using multiple channel adaptive IIR filter is presented. Usually, recursive LMS(RLMS) algorithms for adaptive IIR filters are highly efficient than filtered-X LMS(FXLMS) algorithms, when the order of both algorithms are the same. However, RLMS algorithms usually diverge before the algorithms arenot yet converged. So, the prefilters are presented to improve the stability by pulling the poles of feedback control transfer function in the beginning of active noise control and returning the original poles after the filters converge. The engine noises of diesel engine automobiles and gasoline engine automobiles are analyzed and the mathematical model of an active muffler is derived. Computer simulations and experiments are performed to show the effectiveness of the proposed systems.

• Journal of KSNVE
• /
• v.11 no.3
• /
• pp.401-409
• /
• 2001

Passive type mufflers installed on every car haute inherent problem of lowering engine power and fuel efficiency caused by backpressure which is byproduct of complex internal structure. Recent improvements like installing a calve to change exhaust gas path depending on power requirement and rpm have only marginally improved performance. Tremendous amount of recent research works on active exhaust noise control have failed to commercialize because of numerous physical and economical reasons. In this paper, a unique seal-active muffler using difference of transmission paths is presented. In this system exhaust pipe is divided into two and joined again downstream. Exhaust noise is reduced by destructive interference when two-divided noise join again with transmission paths'difference which is half of the wavelength of a main noise frequency. One divided path has a sliding mechanism to change length thereby transmission path length difference is adjusted to entwine rpm change. The proposed system has minimal backpressure and does not need a secondary sound source like a speaker so it can overcome many problems of failed active noise control methods. We have verified proposed system's superior performance by simulation and comparison experiment with passive mufflers.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.3066-3068
• /
• 2005

Noise can make surrounding environments inferior and deteriorates operation efficiency, and it can bring aural damage as well as give a person psychological stress. Therefore, necessity of study about noise control is increased for better labor conditions and agreeable habitat. In this paper, implementation of active mufflers using a stable IIR adaptive filters is presented. The IIR filter structure is more effective when acoustic feedback exists, but the adaptive IIR filters could be unstable when the filter algorithm is not yet converged. A stabilizing process for adaptive IIR filter is introduced in this paper. Experiments using a TMS320C32 digital signal processor have performed to show the effectiveness of a proposed algorithm.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.334-336
• /
• 2005

According as quality of life improves, pursuit of agreeable iife became realistic problem. Specially, noise had been appraised to element that infiuence in human life directly and indirectly Therefore, necessity of study about noise control is increased for better labor conditions and agreeable habitat. In this paper, implementation of active mufflers using recursive LMS algorithms is presented. Analyze exhaust pipe noise of a gasoline and Diesel car and use adaptation IIR filter algorithm that stability is solidified and controled exhaust pipe noise of a car. computer simulation is performed to show the effectiveness of a proposed algorithm.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.4
• /
• pp.84-90
• /
• 2011

In active noise control filter, LMS algorithms which used for control filter, assure the convergence property, and computational burden of these algorithms are proportionate to the filter taps. The convergence speed of LMS algorithms is mainly determined by value of the convergence coefficient, so optimal selection of the value of convergence coefficient is very important. In this paper, We proposed novel adaptive fuzzy logic LMS algorithms with FIR filter structure which has better convergence speed and less computational burden than conventional LMS algorithms, for single channel active noise control with ill conditioned signal case. Computer simulations were performed to show the effectiveness of a proposed algorithms.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1994.06a
• /
• pp.860-863
• /
• 1994

Main sources of increased vibrations and air noise on ship are main and auxiliary engines and ship ducts. The various ways of transfer of vibration energy and air noise in passenger cabin of a vessel require, in general case, of various methods of attenuation. The transfer of vibration energy from engines through a support requires, alongside with shock-absorbers, availability active shock-absorbers. The transfer of vibration energy and hydrodynamic noise on ship ducts requires availability, alongside with flexible muffler, active mufflers. The availability of air noise from working equipment can require, along with absorbent covers, of space systems of active noise control. In the given article it is spoken about the unified approach to formation of the block-diagram of active noise and vibration control. The complex approach permits to receive additional efficiency in reduction of noise in passenger cabin of vessels.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2671-2673
• /
• 2004

Noise can make surrounding environments inferior and deteriorates operation efficiency, and it can bring aural damage as well as give a person psychological stress. Therefore, necessity of study about noise control is increased for better labor conditions and agreeable habitat. In this paper, implementation of active mufflers using active noise control techniques is presented. The LMS algorithm is used for adaptive filter algorithms. Computer simulations and experiments using TMS320C32 digital signal processor have performed to show the effectiveness of a proposed algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.570-575
• /
• 2019

Active muffler is implemented by applying active noise control technique to reduce exhaust noise of automobile muffler. Conventional Filtered_x LMS algorithm has a problem that the degree of control filter becomes very large and convergence deteriorates when acoustic feedback is present. The recursive LMS algorithm can compensate for this problem because it can be easily diverted in the adaptive filter adaptation process. In this paper, the structure of the primary path and the secondary path transfer function is designed as the IIR filter to improve the convergence performance and the computational burden, and the stabilization filter algorithm is applied to secure stability which is a disadvantage of the IIR filter structure. The stabilization filter algorithm plays a role of pulling the pole into the unit circle to prevent the pole of the transfer function corresponding to the acoustic feedback from diverging during the adaptation process. In this way, the computational burden of the active muffler system and the convergence performance can be improved. In order to show the usefulness of the proposed system, we compared the performance of the proposed Filtered_x LMS algorithm with the performance of the proposed system for the exhaust sound of a diesel engine, which is a variable environment. Compared to conventional algorithm, proposed algorithm's computational burden is less than half, and convergence performances are more than 4 times.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.22 no.2
• /
• pp.251-257
• /
• 1998

Active mufflers have been mainly applied in the large industrial engine due to considerable expense for implementation, but a necessity of development has been increased by the tightened regulation of exhaust noise and the request of high power. In this study, the active muffler prototype for installing in an automobile is designed and constructed. The active muffler is designed so that the primary noise and the control sound are propagated as a plane wave in the outlet. Therefore, the error microphone could be placed outside the high temperature centers of the tail pipe, and the noise radiating to the outside could be reduced in the whole areas around the outlet. For evaluating the control performance of the prototype, the control experiments of band-pass filtered random signal and the modulation of sinusoidal signal which are generated from the primary noise speaker as practical exhaust sound level are implemented. And to investigate the radiation pattern from the outlet of tail pipe and the noise reduction level of points placed adjacent to the outlet, the sound level of adjacent points of thirty is measured.

• Journal of the Korean Society of Costume
• /
• v.56 no.9 s.109
• /
• pp.127-142
• /
• 2006

In this study, I have analyzed Indian traditional clothing in fashion design of 21st century by comparing 1,286 fashion items designed by Indian designers and 722 Western fashion items, which were presented from 2000 S/S to 2005 F/W Formal analysis were made for change in how to wear clothes, and change in items and ornaments. Change of traditional clothing was found in two ways; Western elements added to Indian tradition and Indian traditional image adopted in Western clothing. First, Indian traditional elements added to Western clothing in the formal aspect was found in 83% of Western collections and 27.2% of the Indian designers' collections. In Indian designers' collections, traditional clothing form takes 72.8%, which shows the regional characteristics of India where the traditional clothing is still adhered to in daily life especially by women. Second, from the fashion design of the Indian designers, we can find modernization of sari, change of traditional items into more active and modern way by adding Western clothing; change of form, color and material of traditional items in various ways; and decorative aspects highlighted by adding Indian traditional color, pattern or decoration into Western clothing. In most cases, Western collections are seasoned with Indian traditional image, rather than utilizing the form of Indian clothing. Although adopting the farm of Indian traditional clothing, it can be considered as a translation from the viewpoint of the West. Third, Indian look is expressed in various ways by reproducing Indian traditional ornaments such as earings, bracelets and henna, or by adopting Indian traditional fabric design and decoration in mufflers, bags and etc.