• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.34-40
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• 2001

Aeroacoustic technology to improve the acoustic comfort in high-speed became a major topic in vehicle development process. Although most of wind noise reduction and sound quality improvements are possible with full vehicle, the countermeasures should be applied at the early design stage. Acoustic holography technology was used to identify the external wind noise sources of a vehicle in Hyundai Aeroacoustic Wind Tunnel. Microphone self-noise reduction techniques and several reference microphone positions are investigated in order to obtain proper results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.65-68
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• 2006

Experiments were performed to investigate the effects of mud-flap width on the aeroacoustic noise generation inside high-speed trains. The open-circuit type wind tunnel was used. The measurement setup was custom-built to simulate intercoach spacing. From the measurements, the characteristics of the turbulent flow after the intercoach spacing and consequent generation of aeroacoustic noise inside the cabin was investigated. Especially the effects of mud flap length on the characteristics of the characteristics of the turbulent flow were identified. The mechanism of noise generation by analyzed interactions with structure vibration characteristics and generation characteristics of blocked pressure was investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1207-1214
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• 2001

The paper deals with the computational approach in analysis and design of pantograph panhead strips of high-speed railway in aerodynamic and aeroacoustic concerns. Pantograph is an equipment such that the electric power is supplied from catenary system to train. Due to the nature of complexity in high-speed fluid flow, turbulence and downstream vortices result in the instability in the aerodynamic contact between panhead strips and catenary system, and consequently generate the considerable levels of flow-induced sound. In this paper, based on the preceding low speed wind-tunnel test and simulations, the aerodynamic and aeroacoustic characteristics in low speed are analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.469-472
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• 2007

Aeroacoustic sound induced from inter-couch spacing is an important contributor to interior noise generation for high speed trains. Especially the open space between mud-flap has significant impact from flow-structure interactions. To understand noise generation mechanism, experiments were performed using the wind tunnel. To find mud-flap parameters for minimal noise generations the various shape of the mud-flap was installed and its effects on the wall-pressure generation were investigated.

• 한국소음진동공학회논문집
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• 제18권6호
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• pp.612-618
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• 2008

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet wind tunnel.

• 항공우주기술
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• 제4권1호
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• pp.39-44
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• 2005

로터의 성능 예측 검증을 위해 tilt rotor aeroacoustic model(TRAM)에 대한 3차원 CFD 해석을 수행하였고 로터 파워 효과에 의한 영향을 분석하기 위해 수치해석을 행하였다. 수치 기법은 multiple reference method(MRF)와 sliding mesh technique을 사용하였다. TRAM 실험치와 비교 결과 정지 비행시에는 수치해석이 실험보다 적은 추력을 예측하였고 전진 비행시에는 실험결과와 매우 유사한 결과를 예측하였다. 로터효과를 고려한 비행체의 양력은 감소하고 항력 및 피칭 모멘트는 거의 변화가 없는 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.431-434
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• 2009

Conceptual study of an open-circuit type low-speed wind tunnel for test of wind turbine blade is conducted. The tunnel is constituted of a settling chamber, a contraction, closed and open test sections, a diffuser, two corners, a cross leg and a fan and motor. For the performance test, the closed test section width of 1.8 m, height of 1.8 m and length of 5.25 m is selected. The open test section with dimension width of 1.8 m, height of 1.8 m and length of 4.14 m is adopted for aeroacoustic test. The contraction ratio is 9 to 1 and maximum speed in the closed test section is 67 m/sec. Input power in the tunnel is about 238 kW and its energy ratio is 3.6. The wind tunnel designed in present study will be an effective tool in research and development of wind turbine.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.92-96
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• 2007

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet windtunnel.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.128-134
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• 2014

A Experimental study on frequency characteristics of the microphone array covered with Kevlar in closed test section wind tunnel. Microphones that are flush mounted in a closed test section wall of wind tunnel are subject to very high flow noise resulting from the turbulence in the wall boundary layer. At this time the microphones measure the strong hydrodynamic fluctuations generated by the flow. The phenomena are referred to a microphone self-noise and a method for reducing this has studied. In this paper the array that covered with acoustically transparent Kevlar sheet was designed and made to reduce the flow-induced self-noise. For the validation frequency characteristics of the Kevlar, the microphone array was installed on the wall and test was performed for white noise and sine wave of several frequencies using loudspeaker. In addition, the paper compared the signals as a tension of Kevlar. The results were presented that tend to decrease the sound pressure level at high frequency above 3500Hz according to existence of Kevlar.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.346-347
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• 2010