• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.107-110
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• 1998

차량의 주요 소음원부터 실내 탑승자의 귀의 위치까지 도달되는 소음의 전달에 대한 전체적인 경로 및 주파수특성에 대한 해석은 차량의 구조-음향적인 특성이 복잡하므로 매우 어렵다. 그러나, 중-고주파수에 대한 대책에 있어서는 흡차음재가 유용함은 이미 알려진 사실이다. 차실 벽면에 사용된 흡/차음재는 소음레벨에 부분적인 기여를 함은 물론이고 음질에도 영향을 미친다. 소음 레벨에 있어서는 수백 Hz 이하의 저주파수 성분이 주요하며, 음질에는 중-고주파수 대역의 소음특성이 큰 영향을 미친다[1]. 본 논문에서는, 실험적으로 측정된 소음원의 특성을 수치해석 모델에 이용하여 소음레벨 저감과 음질개선을 위한 흡/차음재의 개선방향을 모색하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.319.1-321
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• 1998

판 구조물의 전달 손실은 효과적인 차음 설계를 위한 필수적인 지표 중 하나이다. 특히, 흡/차음재 부착등 적층에 의한 차음 성능의 변화 예측이 중요하다. 실제의 차음 구조물은 유한한 크기를 갖게 마련인데, 현재까지는무한 판 이론에 제한각이나 경계 손실등을 적용하여 그 값을 산출함으로써 판의 유한효과를 고려하였지만, 해석의 임의성으로 인해 일반적인 적용이 어렵다. 이에 본 연구에서는 흡음재가 부착된 유한한 면적을 갖는 적층판의 음향 전달 손실을 임계 주파수 미만의 주파수 대역에 대해 예측하고 흡음재의 부착에 따른 전달 손실의 변화를 관찰하였다. 판은 무한한 강체 배플위에 있다고 가정하였고, 모드 전개법을 응용하여 개개의 판모드들의 거동을 고려하였다. 여기서 흡음재는 공극질 재료로 가정하여 Biot의 이론을 적용하였다. 해석 결과로부터, 흡음재등이 부착된 적층판에 대해서는 일반적인 제한각의 적용이 어렵고, 그 영향을 충분히 고려할 수 있는 새로운 예측 도구의 필요성을 확인하였다.

• Journal of KSNVE
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• v.16 no.4 s.82
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• pp.15-22
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• 2006

• Journal of KSNVE
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• v.13 no.5
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• pp.282-294
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• 2003

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.569-569
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• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using CFD Code. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.727-728
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• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.619-624
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• 2000

Design of experiments based on Taguchi's orthogonal array is utilized for exploring the design space and for building response surface models of insulator and isolator database in order to facilitate the effective solution of multi-objective optimization commonly occurred in NVH problems. Response surface models, called engineering database of design space, provide an efficient means to rapidly model the trade-off among many conflicting NVH goals in automotive. In the design of insulator and isolator in automotive interior part, it is important not only to construct effective matrices of NVH but also to build up engineering database of current products. The experimental design especially based on orthogonal array and the nonlinear optimization algorithms are successfully used together to obtain the optimal design of insulator and isolator. The $2^{nd}$ order response surface models of absorption coefficient and insertion loss are constructed by using modified Taguchi's $L_{12}2^13^7$ orthogonal array and successfully used in optimal design of insulator and isolator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.197-202
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• 2001

The compressor is one of major noise sources in air conditioner outdoor units, especially deteriorating the sound quality. Therefore, the sound insulation materials layered with sound absorption materials are applied around compressors. In this study, the performance of the sound insulators is examined by measuring the insertion losses in power base and the effects of sound absorption materials, method of application and the shape of the insulators are also investigated. The importance of minimizing the opening is revealed well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.466-471
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• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using PowerFlow. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran. Additionally in order to validate the numerical process, an experimental set-up has been created based on the simplified vehicle. The vibration of the windshield and windows, the total wind noise level results and the relative contributions of the different windows are then presented and compared to measurements. The influence of the flow yaw angle (different wind orientation) is also assessed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.883-889
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• 2011

The brand sound of vehicle diesel engine is recently one of the important advantage strategies in the automotive company. Because various noise components masked under high frequency level can be audible in quieter driving situation. Many researches have been carried out for subjective and objective assessments on vehicle sounds and noises. In particular, the interior sound quality has been one of research fields that can give high quality feature to vehicle products. Vehicle interior noise above 500 Hz is usually controlled by sound package parts. The materials and geometries of sound package parts directly affect on this high frequency noise. This paper describes the sound quality evaluation method for the vehicle diesel engine noise to establish objective criteria for sound quality assessment. Considering the sensitivity of human hearing to impulsive sounds such as diesel noise, the human auditory mechanism was simulated by introducing temporal masking in the time domain. Furthermore, each of the human auditory organs was simulated by computer codes, providing reasonable analytical explanations of typical human hearing responses to diesel noise. This method finally provides the sound quality index of vehicle diesel engine noise that includes high frequency intermittent offensive sounds caused by impacting excitations of combustion and piston slap.