• 소음진동
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• 제8권2호
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• pp.283-288
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• 1998

If one wants to control the noise from a duct, then one must have sufficient number of sensors and actuators so that the control system is observable and controllable. A number of sensors and actuators for control of radiating noise from a duct have to be incorporated with the number of modes which one wants to control. These considerations motivated the present study that considers a control system which has less microphones and actuators than required. In this work, by theoretical analysis and numerical simulation, the control performance and robust reliability of such a kind of control system is investigated in terms of sound-field variables and control system variables. Then the possibility of implementation of the robust radiation power control system is verified by theoretical analysis and numerical simulation. In addition, the control performance of the control system is verified by experiment.

• 소음진동
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• 제6권5호
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• pp.575-585
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• 1996

In order to build a quiet and comfortable ship, the noise levels on board ship must be predicted at early design stage. Statistical Energy Analysis (SEA) developed by R. H. Lyon has been well known to be the most useful frame work to study the energy flow of noise and vibration in structure. This paper applied this theory to predict the transmission loss of structure-borne noise of model structure and has developed computer program. Components constructions model structure have been all considered as SEA elements. And we also estimated the SEA parameters from the model structure. Using SEA and a new conception of STL, we found the transimission character of structure-borne noise theoretically by the idealized ship model, and then compared the results with three cases.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1244-1251
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• 2006

The objective of this paper is to get excitation forces of the engine at each of the brackets for the prediction of the vehicle interior noise by the powertrain. A powertrain geometry model is produced by CATIA and its FE model is made by MSC/Patran. A vibration mode analysis and a running mode analysis are experimentally implemented. After getting a satisfied MAC value by doing a correlation about a measured mode analysis value and analyzed value through MSC/Nastran software, all components are assembled through MSC/ADAMS software which is a dynamic analysis tool. We can predict the vibration of brackets which is the last points to occur the force of the engine combustion by analyzing the combustion force produced by engine mechanism.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.891-896
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• 2007

Noise radiated from the powertrain is an important factor of the vehicle interior noise. In this paper, Finite Element(FE) model and Boundary Element(BE) models were created. The FE model was updated by doing a correlation between experimental modal analysis(EMA) values and finite element analysis(FEA) values. Main bearing forces were calculated using a running modal data. The forced vibration analysis was simulated using the software MSC/NASTRAN, and the radiated noise was predicted using the software LMS/VIRTUAL.LAB.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.501-506
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• 2007

Structure-borne noise is the interior noise that results from the low frequency vibrational energy transmitted through those body and joint parts. The relation between the excitation of powertrain and resultant interior sound must be analyzed in order to identify and predict the structure borne noise. The method of acoustic source excitation is preferred than the method of mechanical force excitation to measure the NTF(noise transfer function). Because acoustical method is more convenient and reliable. In this paper, to analysis and identify vehicle interior noise by powertrain is performed, and the vibro-acoustic transfer function is extracted from experimental measurement. These are important step of TPA(transfer path analysis) to identify effect of interior noise resulted from powertrain running excitation.

• 한국자동차공학회논문집
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• 제1권1호
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• pp.110-119
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• 1993

본 논문은 자동변속기를 탑재한 차량에서 에어콘(air condition)을 작동시키고, 공 회전시 기어의 변속을 "D"단에 두었을 때 실내에서 발생하는 이상음의 원인규명 및 해결 방 법에 관한 연구 결과를 논하고자 한다. 이 이상한 소음의 원인을 규명하기 위하여 실린더 내부의 연소압력, 메인 베어링캡(main bearing cap)의 진동, 엔진 마운팅 보스의 진동 및 차 량의 실내소음을 동시에 측정하여 분석하였으며 이 결과에 의하면 이상음의 원인은 크랭크 샤프트(crank shaft)의 굽힘진동이 파워플랜트(power plant)를 가진하여 진동을 증가시키고, 이 진동이 마운팅 보스를 통하여 차량의 차체에 전달되며, 차체의 진동에 의해서 발생하는 고체 전달음(structure-borne noise)이었다. 또한 이상음의 주기는 주파수 성분은 200-400Hz 이었다. 이 이상음은 크랭크 샤프트의 댐퍼 풀리의 질량을 저감하여 크랭크 샤프트의 동특 성을 개선함으로서 해결가능하고, 혹은 점화시기를 지연하여 연소 압력을 낮춤으로서 해결 가능하다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.265-270
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• 2001

For the reduction and efficient management of railway noise, first of all prediction of railway noise is necessarily requested, At home and abroad, many studies for prediction of railway nearby noise have been accomplished, But it is impossible to predict exactly for the Korean Railroad, because the acoustic power DB for each rolling stock used in Korea has not been builded yet. So in this study, acoustic power DB for each Korean rolling stock such as Samaeul, Mugungwha was builded according to the speed and rail support systems. Predicted results using accumulated acoustic power DB are compared with measured results and it is known that accumulated acoustic power DB can be used for more precise prediction of railway nearby noise.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.527-534
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• 2004

This study is a paper relating to between road traffic noise(RTN) and sound power level(PWL). At present to prediction of RTN is used to many experimental models and prediction methods. RTN is computed PWL using existing experimental models and prediction methods. Then, computed PWL is compared with it of measurement value, in them, it is selected model most similar to measurement value. And then, this results will watch for make Noise Map, as application field applied to computed results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.688-691
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• 2004

We have studied the possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work (1,2), the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. The possibility of total acoustic potential energy reduction by acoustic source power control is examined in an acoustically small cavity. Using acoustic energy balance equation, the relation between global noise control performance and absorptive material's arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent's distribution and impedance.

• 한국소음진동공학회논문집
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• 제21권5호
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• pp.430-436
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• 2011

The purpose of this study is to analyze the vibration and sound generation characteristics of the sandwich panel. Two thick panels were assumed to be separated by a compliant viscoelastic core. The transverse vibration induced by an external impact was analyzed using the Rayleigh-Ritz method. For applying arbitrary boundary condition of the panels, the edges were assumed to be supported by the translational and rotational springs. The beam functions were used as the trial functions. The effect of the boundary condition and viscoelastic core on the resulting vibration characteristics was investigated. The radiated sound power was analyzed using the proposed numerical model and the Rayleigh integral. The dynamic properties of the core and the mass-stiffness-mass resonance frequency had significant influence on the impact sound.