• 한국항공운항학회지
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• 제20권3호
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• pp.44-50
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• 2012

The noise reduction is important one of considerations in the process of a civil aircraft development program. External noise sources are classified into an air-born source and a structure-born source. Among these noise sources, the most affected noise source into a cabin is the air-born noise source from an engine or propeller. The external noise is transmitted into the cabin through the fuselage structure of airplane which are composed of an fuselage structure, an interior trim panel and an acoustic insulation layer between an fuselage structure and an interior trim panel. Therefore, appropriate fuselage structure and acoustic insulation layer is very important to reduce the internal noise level. In this paper, the vibro-acoustic coupled analysis of the cabin noise of the 80~90 seats regional turboprop aircraft is carried out to validate the acoustic analysis method using Direct BEM and FEM. The sound pressure level onto the fuselage skin is acquired by fan-source noise analysis using BEM, and which sound pressure is used as acoustic noise source in vibro-acoustic noise analysis for cabin noise analysis using FEM.

• KIEAE Journal
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• 제10권4호
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• pp.39-44
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• 2010

Reading room in the university is one of necessary facilities that university student must use. It is, therefore, very important to make reading room comfortable acoustically not only to minimize the annoyance to the users but also to provide efficiency in studying. Present study aims to investigate the current situation of reading room in terms of acoustics and moreover to find out the relationship between the indoor noise and users' satisfaction through questionnaire survey. As a result, the indoor noise level is quite higher than the 1st grade, 35 dB(A), that the Ministry of land, transport and maritime affairs suggests as certificate regulation for environment friendly building and there were lots of noise sources that can provoke users in studying or concentrating. Questionnaire survey illustrates that the sound when opening and closing door, and airborne sound from outdoor transmitted through window are most annoying, which affected users' dissatisfaction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.185-191
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• 1999

This paper deals with a method to predict the noise level inside metro electric cars running a single-line tunnel at the speed of 80km per hour using ray tracing method, a kind of ray acoustics generally used for a high-frequency and air-born noise analysis. The interior of the car including a under-frame, seats, side doors, end doors, door-pockets, side panels, end panel, a roof panel and so on is modeled. And in order to describe the noise power coming inside, artificial noise sources are designated using sound transmission loss data of each section measured from simple tests and external noise level. The noise level inside the car is calculated and its properties are investigated. The results satisfy the criteria on noise level inside the car.

• 대한기계학회논문집
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• 제14권5호
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• pp.1096-1103
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• 1990

본 연구에서는 Fig.1과 같은 열린 경제(open boundary)를 갖는 일반적인 형태 의 3차원 풍동에 대한 공진 특성을 구하여 이를 실험과 비교한다.이런 풍동에 공진 진동수와 일치하는 규칙적인 가진을 주면, 유동 특성은 현저하게 변하게 된다. 일반 적으로, 이러한 임의의 형태를 갖는 풍동의 공진 진동수와 모드는 이론적인 방법으로 예측하기는 매우 힘들다. 이런 경우에 유한요소법은 매우 유용한 방법이다.

• 대한기계학회논문집
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• 제15권3호
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• pp.824-833
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• 1991

본 연구에서는 차체구조계의 진동모드 변수와 차실음향계의 음향모드변수들이 어떻게 관련되어 차실소음을 결정하는 가를 밝혔다. 그 결과, 수치해석 결과의 효용 성을 높이고 실내소음 평가방법을 체계화 시킬 수 있었으며, 효과적인 소음저감을 위 한 유용한 자료를 얻을 수가 있었다. 한편, 이제까지의 차실소음의 응답해석에서 가 장 큰 오차의 발생요인은 차체의 구조진동 모드데이타인데, 본 연구에서는 유한요소해 석 대신 모드시험 결과를 이용함으써, 유한요소 모델리이 어려운 경우의 소음 해석의 신뢰도를 높일수가 있었다.

• 한국실내디자인학회논문집
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• 제19권3호
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• pp.77-85
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• 2010

The Therme Vals is a hotel and spa which combines a complete sensory experience designed by Peter Zumthor. This study aims to find emotional design approaches of the Therme Vals through references, observation from site visit, interview and discussion related to this topic. This space was designed for visitors to luxuriate and rediscover the ancient benefits of bathing. The combinations of light and shade, open and enclosed spaces and linear elements make for a highly sensuous and restorative experience. The study observed the emotional design characteristics of the Therme Vals through space approach, aesthetic and experiential sides. For space approach side, emotional experience in gradual process to approach the space was mentioned, for aesthetic side, mystical combination of light, stone and water was observed, for experiential side, 5 senses experience and space programing for adjusting the density of the space were observed. This study found that the spa has the quality of spiritual, soul-touching delight like religious experience. The fascination for the mystic qualities of a world of stone within the mountain, for darkness and light, for light reflections on the water or in the steam saturated air, pleasure in the unique acoustics of the bubbling water in a world of stone, the ritual of bathing-all these notions were explained in Peter Zumthor's construction details. In the result of the interview and discussion, people love the space and praised it highly for the emotional design regardless of space experience, age, sex or ethnicity. Emotional design approaches based on human nature, materiality, and memory of the places is more powerful than other emotional design ideas with technical devices, special themes, digital effects, vivid colors and shapes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.557-561
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• 2014

In this work, Altair Engineering's vibroacoustic modeling approach is used to simulate the acoustic signature of a simplified automobile in a wind tunnel. The modeling approach relies on a two step procedure involving simulation and extraction of acoustic sources using a high fidelity Computational Fluid Dynamics (CFD) simulation followed by propagation of the acoustic energy within the structure and passenger compartment using a structural dynamics solver. The tools necessary to complete this process are contained within Altair's HyperWorks CAE software suite. The CFD simulations are performed using AcuSolve and the structural simulations are performed using OptiStruct. This vibroacoustics simulation methodology relies on calculation of the acoustic sources from the flow solution computed by AcuSolve. The sources are based on Lighthill's analogy and are sampled directly on the acoustic mesh. Once the acoustic sources have been computed, they are transformed into the frequency domain using a Fast Fourier Transform (FFT) with advanced sampling and are subsequently used in the structural acoustics model. Although this approach does require the CFD solver to have knowledge of the acoustic simulation domain a priori, it avoids modeling errors introduced by evaluation of the acoustic source terms using dissimilar meshes and numerical methods. The aforementioned modeling approach is demonstrated on the Hyundai Simplified Model (HSM) geometry in this work. This geometry contains flow features that are representative of the dominant noise sources in a typical automobile design; namely vortex shedding from the passenger compartment A-pillar and bluff body shedding from the side view mirrors. The geometry also contains a thick poroelastic material on the interior that acts to reduce the acoustic noise. This material is modeled using a Biot material formulation during the structural acoustic simulation. Successful prediction of the acoustic noise within the HSM geometry serves to validate the vibroacoustic modeling approach for automotive applications.