• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.501-509
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• 2003

A method of identifying structural parameters such as stiffness and damping coefficients at interfacial points of vibro-acoustic systems is suggested using an optimization technique. To identify the parameters using a numerical optimization algorithm, cost functions are defined. The cost function should be zero at the correct parameter values. To minimize the cost functions using an optimization technique, a design sensitivity analysis procedure is developed in the framework of the multi-domain FRF-based substructuring method. As a numerical example, a ladder-like structure problem is introduced. With known parameter values and different initial guesses of the parameters, convergence characteristics to the exact value are compared for the three cost functions. Investigating the contours of the cost functions, we find the first cost function has the largest convergent region to the correct value. As another practical problem, stiffnesses of engine mounts and bushings in a passenger car are identified. The numerical examples show that the proposed method is efficient and accurate even when applied to realistic problems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.495-499
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• 2000

The booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Thus the engine mounting system must be cautiously designed to reduce the noise. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To effectively use the method, the concept of 'effectiveness' is introduced to identify the contributions of each vibration sources and transmission paths to interior noise. When the magnitudes and phases of the forces due to the engine vibration are changed, the synthesized interior booming noise level is predicted by the vector synthesis diagram. Thus, the optimum characteristics of the forces are obtained through the simulations of the vector synthesis analysis. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.635-644
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• 2004

A method of identifying structural parameters such as stiffness and damping coefficients at interfacial points of vibro-acoustic systems is suggested using an optimization technique. To identify the parameters using a numerical optimization algorithm, cost functions are defined. The cost function should be zero at the correct parameter values. To minimize the cost functions using an optimization technique, a design sensitivity analysis procedure is developed in the framework of the multi-domain FRF-based substructuring method. As a numerical example, a ladder-like structure problem is introduced. With known parameter values and different initial guesses of the parameters, convergence characteristics to the exact value are compared f3r the three cost functions. Investigating the contours of the cost functions, we find the first cost function has the largest convergent region to the correct value. As another practical problem, stiffnesses of engine mounts and bushings in a passenger car are identified. The numerical examples show that the proposed method is efficient and accurate far realistic problems.

• 한국소음진동공학회논문집
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• 제14권6호
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• pp.536-545
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• 2004

A method of identifying structural parameters such as stiffness and damping coefficients at interfacial points of vibro-acoustic systems is suggested using an optimization technique. To identify the parameters using a numerical optimization algorithm, cost functions are defined. The cost function should be zero at the correct parameter values. To minimize the cost functions using an optimization technique, a design sensitivity analysis procedure is developed in the framework of the multi-domain FRF-based substructuring method. As a numerical example, a ladder-like structure problem is introduced. With known parameter values and different initial guesses of the parameters, convergence characteristics to the exact value are compared for the three cost functions. Investigating the contours of the cost functions, we find the first cost function has the largest convergent region to the correct value. As another practical problem, the stiffnesses of engine mounts and bushings in a passenger car are identified. The numerical examples show that the proposed method is efficient and accurate for realistic problems.

• 한국소음진동공학회논문집
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• 제24권12호
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• pp.935-942
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• 2014

The ride quality investigation is on-going topic in the car industry since its global standard has not evaluated and it is difficult to point out one part that hinders the ride quality. Since the traditional transfer path analysis that is widely used in car industry to investigate the ride quality requires a lot of test time to process the full data so that there are problems to conduct in industry. Based on these disadvantages, new approaches have developed such as OPAX(operational path analysis with eXogeneous inputs) and OTPA(operational transfer path analysis) for last decades. The OTPA only requires the operational data for evaluate the contribution of vibration sources and the OPAX has advantage of using parametric model to estimate the operating load and needs a minimum set of extra tests with excitation. In this paper, for evaluating the hindrance of ride quality two methods are used and the result is compared with another result of a car having higher ride quality.

• 한국소음진동공학회논문집
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• 제18권8호
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• pp.805-815
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• 2008

Transfer path analysis(TPA) and panel contribution analysis(PCA) have been used widely to reduce interior noise of mechanical systems. TPA enables us to decompose interior noise into air-borne and structure-borne noises and estimate the path contribution of noise sources. PCA is also used to identify the noise contribution of each sub-panel in vibro-acoustic systems. In this paper, TPA and PCA are applied to wheel loader, one of the heavy construction equipments. Firstly, TPA for air-borne noise is conducted to estimate the contribution of air-borne sources using pressure transfer function. Thereafter, TPA for structure -borne noise is employed to verify the results of air-borne source quantification through the synthesis of two results. Secondly, PCA is performed by both TPA using pressure transfer function between panels inside the cabin and boundry element method(BEM) for the cabin of wheel loader with various boundary conditions. As a results, it was found that TPA conducted by experiments and PCA accomplished by both experiments and BEM are very effective methods in analyzing the path and contribution of the noises for reducing an interior noise level in the wheel loader system.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.65-73
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• 2015

The ride quality has become a key component of not only design but car selling as the technology developed and the requirement of passengers grew up. Thus car industry invests lots of time and cost for the higher ride quality. The evaluation of the ride quality mainly is expressed by subjective element that drivers felt. In this paper, instead of the original transfer path analysis method, relatively new methods such as OPAX(Operational path analysis with eXogeneous inputs) and OTPA(operational transfer path analysis) are used for analyzing the main hindrance element of ride quality. With those new method, contribution rate of all paths that the vibration propagate along analyzed after driving test on the roads having different characteristic. The comprehensive hindrance elements of ride quality are deduced from the contribution rate and the improve experiment by changing one of hindrance elements for higher ride quality.

• 대한기계학회논문집A
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• 제36권4호
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• pp.457-463
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• 2012

기저막은 달팽이관의 한 기관으로서 주파수 대역에 따라 기저막의 최대 진폭 발생 위치가 변화하여 소리를 인지할 수 있게 되며 이는 기저막의 형상에 기인한다. 본 연구에서는 인공기저막 기반의 완전 삽입형 인공와우 개발을 위한 연구의 일환으로써 주파수 분리 대역폭을 보다 확장시킬 수 있는 기저막의 형상을 제안하기 위해 설계 인자 연구를 수행하였다. 상용 유한요소소프트웨어 Abaqus 를 이용한 유한요소 해석을 통해 인공기저막의 음향 진동 특성을 예측하였으며 해석결과는 실험결과와 비교하여 검증하였다. 기저막 모델의 다양한 형상 변화와 기저막 모델에 존재하는 잔류응력에 따른 주파수 분리 대역의 변화 추이를 설계 인자 연구를 통하여 제시하였다.