• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.526-531
• /
• 2011

A dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train. Meanwhile, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it seems important to provide an optimal design scheme incorporating sound packages such as dash isolation pad and carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. The system taken into account in this paper is a dash panel component of a sedan, which includes A pillar, front side member, dash panel and the corresponding sound packages. Design variables such as panel thickness and sound package layers are investigated how they are related for the better radiation performance (i.e. structure-borne) and sound transmission loss (i.e. air borne).

• International Journal of Automotive Technology
• /
• v.8 no.1
• /
• pp.67-73
• /
• 2007

This study analyzes the interior noise that is generated during acceleration of a passenger car in terms of car body structure and panel contribution. According to the transfer method, interior noise is classified into structure-borne noise and air-borne noise. Structure-borne noise is generated when the engine's vibration energy, an excitation source, is transferred to the car body through the engine mount and the driving system and the panel of the car body vibrates. When structure-borne noise resonates in the acoustic cavity of the car interior, acute booming noise is generated. This study describes plans for improving the car body structure and the panel form through a cause analysis of frequency ranges where the sound pressure level of the rear seat relative to the front seat is high. To this end, an analysis of the correlation between body attachment stiffness and acoustic sensitivity as well as a panel sensitive component analysis were conducted through a structural sound field coupled analysis. Through this study, via research on improving the car body structure in terms of reducing rear seat noise, stable performance improvement and light weight design before the proto-car stage can be realized. Reduction of the development period and test car stage is also anticipated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.10
• /
• pp.537-544
• /
• 2009

On account of the technological development, intelligent building is on increasing where the artificial regulation on indoor environment is possible, thence the concern about those facilities such as water-supply facility, water-heater and drainage facility has becomes higher. However, due to diversification and complicated system of the facility-equipments, the noise generating from such facility equipment is gradually becoming a problem, and since especially equipment noises arising at the machine room frequently infringe into the resident's pleasant living environment with the complex types of an air-borne sound and a structure-borne sound, it is becoming the civil complaint. On such viewpoint, this Study ever observed the characteristics of noise generating from various facility-equipments in the building, and intended to evaluate the facility-noises by use of the valuation index such as PSIL, N, NC, NR. As result of, the facilities noise which happens in the machine room makes normal conversation very difficult due to high sound pressure level. Based on such data, this study is willing to present it as an essential material for establishment an efficient measure against the facility-noises arising at machine room hereafter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.194-202
• /
• 2009

The paper deals with the countermeasure against structure-borne noise source and noise reduction of drainage pipes. Recently, the problem the problem of the toilet drain noise of an apartment house has been become the center of public interest and a target of public grievance. Generally, the drain noise of a toilet in the apartment house has a pink noise characteristics below 2 kHz level, and therefore, the structure-borne noise has a great effect on the entire drain noise. In order to measure the transmission loss for various kinds of pipes such as PVC pipes, cast-iron pipes and newly developed AS pipes, experimental setup containing speakers as a sound source was designed and manufactured. The second-stories measurement room with a small size anechoic chamber was constructed and the noise level for different kinds of drainage pipes was measured by the sound level meter. Through the experimental research in the study, noise reduction capacity for various kinds of drainage pipes and countermeasures against structure-borne noise source are demonstrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.1
• /
• pp.22-28
• /
• 2012

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

• The Journal of the Acoustical Society of Korea
• /
• v.32 no.5
• /
• pp.402-407
• /
• 2013

In this paper, an analysis of sound propagation between two rooms with different mediums is discussed. Statistical energy analysis (SEA) is used to consider energy equilibrium among subsystems associated with the sound pressure levels in two rooms and the vibration level of the wall between rooms. Effect of the sound radiation from the structure-borne noise of the wall on sound pressure level of the receiving room is investigated. For a numerical example, sound propagation between engine room and water tank joined by a steel plate whose size is $8.4{\times}4$ m, is considered. It is found that when the critical frequency of the plate is above the frequency range of interest, the sound pressure level in the water tank is dominated by sound transmission through the plate, while sound radiation from the structure-borne noise of the plate is negligible except low frequency range below 63 Hz.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.10
• /
• pp.758-765
• /
• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.917-923
• /
• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• The Journal of the Acoustical Society of Korea
• /
• v.10 no.2
• /
• pp.68-77
• /
• 1991

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.667-672
• /
• 2007

The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. In this paper, the train noise and structure borne noise by train are measured. From the results, we investigated the effect on the sound absorption tunnel for elevated railway.