• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.391-398
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• 1998

The intake noise, a major source of vehicle noises, has rapidly become a noticeable, and has been studied to reduce the level. Traditionally, the intake system has been developed through the road test and the experiment using a engine dynamo, namely, the trial and error process. This approach require very high cost and long time consuming to develop the system. In this study, the simulator which had a speaker in the cylinder head was presented. It was easy to analyze the acoustic characteristic of the intake system in laboratory environment. This study presented a improvement to reduce the level of the intake noise using the Transfer Matrix Method and NIT/SYSNOISE, FE analysis commercial software. It was to select optimum position of a resonator and verified by the simulator. This simulator can be used early in the design stage of development of the intake system.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.183-189
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• 2003

The study of the automotive noise reduction has been concentrated on the reduction of the automotive engine noise because the engine noise is the major cause of automotive noise. However, many studies of automotive engine noise led to the interest of the noise reduction of the exhaust and intake system. Recently, the active control method is used to reduce the noise of an automotive exhaust and intake system. It is mostly used the LMS(Least-Mean-Square) algorithm as an algorithm of active control because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an Active Noise Control system. However, the convergence performance of LMS algorithm went bad when the FXLMS algorithm was applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to solve this problem, the modified FXLMS algorithm is proposed. In this study, the improvement of the control performance using the modified FXLMS algorithm under rapidly and suddenly accelerated driving conditions was identified. Also, the performance of an active control using the LMS algorithm under rapidly accelerated driving conditions was evaluated through the theoretical derivation using a chirp signal to have similar characteristics with the induction noise signal.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.546-552
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• 2015

In the previous study, the air flow noise around 1.6 k~1.8 kHz was analyzed, and could be reduced by machining a groove in the bore of compressor inlet in front of the main blades of a compressor wheel. It was proven that this groove was very effective for removing the noise without critical sacrifice of compressor performance, and in addition, it did not noticeably deteriorate vehicle performance, drivability and acceleration. It is interesting that the type of groove tried for 1.6~1.8 kHz noise reduction could be effective for another air flow noise, 4 k~6 kHz which is the 3rd order frequency range of turbocharger speed. This study tried various shapes of grooves for minimizing engine performance difference as well as reducing the 3rd order noise. Finally, it was shown that the groove should be round for the engine performance, and an optimal size exist for the noise and the engine performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.715-718
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• 2002

자동차 및 유체기계의 흡기계나 배기계에 사용되는 소음기의 음향성능은 전달손실로 기계성능은 배압으로 표현된다.유체가 흐르는 관 사이의 임피던스 부정합을 이용하는 반사형 소음기의 경우, 내부 유로에 천공을 주어 음향감쇠를 시키거나 유동을 안정시키는 경우가 많다.본 연구에서는 동심관형 공명기의 내부 관에 존재하는 천공의 분포 양상의 변화가 공명기 내부의 유동장에 미치는 영향을 살펴보고, 그 유동장의 변화에 따라서 소음기의 성능이 어떠한 영향을 받게 되는지를 고찰하였다.또한 유동장에 영향을 미치며, 소음기의 설계 인자 중 하나인 면적 확장비의 변화가 유동장 및 배압에 미치는 영향을 예측하였다.이로부터 유동의 흐름을 제어하여 소음기의 성능을 향상시키는 방법을 찾고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.551-554
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• 2005

The method of the reduction of the automotive induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, When the Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. Thus Normalized FXLMS algorithm was developed to improve the control performance under the rapid acceleration. The advantage of Normalized FXLMS algorithm is that the step size is no longer constant. Instead, it varies with time. But there is one additional practical difficulty that can arise when a nonstationary input is used. If the input is zero for consecutive samples, then the step size becomes unbounded. So, in order to solve this problem. the Correlation FXLMS algorithm was developed. The Correlation FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Correlation FXLMS Is presented in comparison with that of the other FXLMS algorithms based on computer simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1016-1019
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• 2004

The study of the noise reduction of an automobile has been concentrated on the reduction of the automotive engine noise because the engine noise is the major cause of automotive noise. However, many studies of automotive engine noise led to the interest of the noise reduction of the exhaust and intake system. The method of the reduction of the induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to this problem, the modified FXLMS algorithm using Moving Bandpass Filter was proposed. In this study, MBPF was implemented and use ANC for automotive intake under revived rapidly accelerated driving conditions and it was verified its performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.515-519
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• 2002

자동차 및 유체기계의 흡기계나 배기계에 사용되는 소음기의 음향성능은 전달손실로 기계성능은 배압으로 표현된다. 유체가 흐르는 관 사이의 임피던스 부정합을 이용하는 반사형 소음기의 경우, 내부 유로에 천공을 주어 음향감쇠를 시키거나 유동을 안정시키는 경우가 많다. 본 연구에서는 동심관형 공명기의 내부 관에 존재하는 천공의 분포 양상이 소음기의 전달손실과 배압에 미치는 영향을 실험을 통하여 고찰하였다. 내부관의 평균 천공율은 일정하지만 길이 방향을 따라서 천공율이 변하는 다섯가지의 공명기에 대한 실험을 수행하고, 성능에 미치는 영향을 살펴보았다. 전달손실은 천공요소의 임피던스 모델을 고려하여 예측한 결과와 비교하였고, 측정된 배압은 모의 해석 결과와 비교하였다. 분석 결과, 천공율이 점점 작아지는 분포나, 작았다가 커진후 다시 작아지는 형태의 분포를 가질 경우, 배압 측면에서 매우 유리하고, 음향 전달손실도 큰 차이가 없음을 밝혔다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.460-465
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• 1997

In the begining stage of development of a new automobile, decision of appropriate positions and room of resonators is important to NVH engineers. To find optimized positions of resonators of an automotive intake system, numerical approach such as acoustic FEM or BEM and experimental work are possible. However, either method requires many efforts and time to prepare a numerical or a real model. This research demonstrates easy way to design an adequate intake system.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.1
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• pp.1-10
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• 1984

1982년 8월에 Toyota가 전자제어시스템을 갖춘 새로운 디이젤기관을 선보였다. 이 제어시스템 들은 연료의 분사량, 분사시간, 아이들링속도, 글로우 플러그(glow plug)전류 및 흡기량의 최적 제어를 할 수 있도록 하였다. 이로써 높은 기관성능, 즉 훌륭한 연료절약효과와 양호한 운전성 능에 기관의 소음이나 진동의 저감 등에 큰 이점들을 얻을 수 있게 된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.371.2-371
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• 2002

자동차 및 유체기계의 흡기계나 배기계에 사용되는 소음기의 음향 성능은 전달손실로 기계성능은 배압으로 표현된다. 유체가 흐르는 관 사이의 임피던스 부정합을 이용하는 반사형 소음기의 경우, 내부 유로에 천공을 주어 음향 감쇠를 시키거나 유동을 안정시키는 경우가 많다. 본 연구에서는 동심관형 공명기의 내부 관에 존재하는 천공의 분포양상이 공명기 내부의 유동장에 어떤 영향을 미치며, 그 유동장의 변화에 따라서 소음기의 성능에 어떠한 영향을 미치게 되는지를 고찰하였다. (중략)