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이부영(Booyeong Lee),홍준기(Jun-gi Hong),김민성(Minsung Kim),임종혁(Jonghyuk Lim),임형빈(Hyungbin Im),박강일(Kang-il Park),정진태(Jintai Chung) 한국소음진동공학회 2018 한국소음진동공학회 논문집 Vol.28 No.2
In this study, we studied fan noise reduction of a vehicle BSG (belt driven starter & generator) motor. The noise levels and frequency spectra of the BSG motor were measured experimentally. Based on these results, the blade passing frequency (BPF) generated by the fan was proven to be the main noise source of the BSG motor. In order to reduce the fan noise, design parameters of the fan were selected and noise analysis was performed through simulation. Using the design of experiments, the influence of the design parameters on the noise was analyzed and the fan design to reduce the fan noise was performed. Finally, the improved fan was manufactured and the noise test was performed. The noise level of the BSG motor with the improved fan was evaluated by comparison with the noise level of the existing BSG motor.
이부영(Booyeong Lee),류석원(Seokwon Ryu),정진태(Jintai Chung) 한국소음진동공학회 2020 한국소음진동공학회 논문집 Vol.30 No.1
In this study, we identified structure-born noise in a household air purifier and presented a method for reducing such noise. After noise signals from the air purifier were measured using a microphone, a frequency analysis was conducted to find the source of the noise. To identify the location where the structure-born noise originated, the vibration signals of the scroll were measured, and the frequency components of the measured signals were compared with the noise frequency components. The experimental results confirmed that a forced vibration occurs in the scroll of an air purifier owing to a pressure change caused by the impeller rotation, and this vibration induces the structure- born noise. In addition, modal testing showed that the structure-born noise is amplified when the natural frequency of the scroll radiating the noise coincides with the blade passing frequency. Finally, to reduce the structure-born noise, a damping material was attached to the scroll, and it was then experimentally confirmed that the overall sound pressure level was reduced by 1.2 dBA.