• 한국소음진동공학회논문집
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• 제23권5호
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• pp.414-422
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• 2013

As structure-borne sound, the floor impact sound is one of the serious noises in residential building. Most of heating system applied to the typical Korean residential building is floor heating system which is called ondol. The ondol usually consists of finishing material, mortar with heating coil, light-weight aerated concrete and reinforced concrete. This study focused on the isolation of heavy-weight impact sound and modification of mortar and light-weight aerated concrete. Specifically the glass foam aggregate was added on light-weight aerated concrete. Also, water-cement ratio and amount of cement on mortar were revised. The sound pressure level of heavy-weight impact was measured in reverberation chamber using both bang-machine and impact ball. The size of specimen was 1 m by 1 m. Substitution ratio of glass foam aggregate on light-weight aerated concrete shows relationship with heavy-weight impact sound pressure level. In addition, heavy-weight impact sound pressure level was decreased with increment of water-cement ratio and amount of cement on mortar.

• ETRI Journal
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• 제31권6호
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• pp.680-687
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• 2009

This paper reports on an improved piezoelectric microspeaker with a high sound pressure level of 90 dB, a total harmonic distortion of less than 15%, and coherence higher than 0.9. The fabricated Pb(Zr,Ti)$O_3$ (PZT) microspeakers have a thickness of only 1 mm including the speaker frame and an active area of 18 mm${\times}$20 mm. To achieve higher sound pressure and lower distortion, the PZT piezoelectric microspeaker has a well-designed speaker frame and a piezoelectric diaphragm consisting of a tilted PZT membrane and silicone buffer layer. From the simulation and measurement results, we confirmed that the silicon buffer layer can lower the first resonant frequency, which enhances the microspeaker's sound pressure at a low frequency range and can also reduce useless distortion generated by the harmonics. The fabricated PZT piezoelectric microspeakers are implemented on a multichannel speaker array system for personal acoustical space generation. The output sound pressure at a 30 cm distance away from the center of the speaker line array is 15 dB higher than the sound pressure at the neighboring region 30 degrees from the vertical axis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.273-278
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• 2002

Booming sound is one of the most important interior sound of a passenger car. The conventional booming noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level can not give the whole story about the booming sound of a passenger car. In this paper, we employed sound metric which is the subjective parameter used in psycoacoustics. According to recent research results, the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network theory has been applied to derivation of sound quality index for booming sound of a passenger car.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.628-634
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• 2003

Rumbling sound is one of the most important interior sound of a passenger cu. The conventional rumbling noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level can not give the whole story about the rumbling sound of a passenger car. In this paper, we employed sound metric which is the subjective parameter used in psycoacoustics. According to recent research results, the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network th[ ory has been applied to derivation of sound quality index fur rumbling sound of a passenger car.

• Journal of Advanced Marine Engineering and Technology
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• 제40권6호
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• pp.468-475
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• 2016

본 연구에서는 기존 열회수형 환기장치의 음향 문제점을 파악하고, 흡음덕트 설치위치별 열회수형 환기장치의 소음저감 방안을 강구하기 위하여 관련된 국내 외 규격을 기준으로 열회수형 환기장치의 크기, 풍량 및 흡음덕트 길이를 파라미터로 한 발생소음을 측정하여 비교하고 고찰하였다. 그 결과, 무향실에서 열회수형 환기장치에 대한 소음은 흡음덕트를 설치하지 않았을 경우에 소형 및 중형 모두 풍량에 관계없이 거의 대부분 소음기준인 50 dB(A) 보다 높게 나타났고, 흡음덕트를 설치하였을 경우에는 소음도가 감소됨을 알았다. 또한, 흡음덕트의 길이에 따른 주파수 대역별 음압수준은 소형과 중형 열회수형 환기장치에서 흡음덕트의 길이가 클수록 대체적으로 감소하였고, 풍량이 클수록 대체적으로 음압수준이 증가하였다.

• 한국화재소방학회논문지
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• 제33권1호
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• pp.105-112
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• 2019

본 연구에서는 T자형의 복도 연결 공간에서 비상 방송음이 명료하고 고르게 전달되는지를 건축음향 시뮬레이션을 이용하여 알아보았다. 복도 공간의 흡음성능 변화, 비상 방송용 확성기의 설치 위치와 간격을 변화시켜 보았으며 변화에 따른 음압 레벨 분포, 음성 전달 지수(STI, RASTI) 분포를 비교하였다. 시뮬레이션 결과 명료한 음성 전달을 위해서는 비상 방송용 확성기를 T자형 복도 연결부의 중심에서 약 10 m를 이격시켜 설치하는 것이 좋은 것으로 나타났다. NFSC의 25 m 설치 간격을 좁히는 경우 더욱 명료하고 충분한 음량을 갖는 비상 방송음이 고르게 전달될 수 있는 것으로 나타났다.

• 한국음향학회지
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• 제42권2호
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• pp.143-151
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• 2023

본 논문은 표준 중량충격원을 이용한 건축물의 바닥충격음 차단성능을 측정하는 경우 측정불확도를 평가하는 방법을 다루었다. 반복 측정의 영향 이외에도 측정 위치의 영향, 가진 위치의 영향, 음압측정에 사용된 장비의 영향 및 충격원의 영향 등을 고려하였다. 평균 최대 바닥충격음 레벨 측정의 수학적 모델을 제시하고 요인별 불확도 평가방법을 제안하였으며, 제안한 방법을 실제 측정 결과에 적용하여 평균 최대 바닥충격음 레벨 및 측정불확도를 평가하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.997-1002
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• 2004

Rumbling sound is one of the most important interior sound of a passenger car. The conventional rumbling noise research was focused on the reduction of the A-weighted sound pressure level. However A-weighted sound pressure level can not give the whole story about the rumbling sound of a passenger car. In this paper, we employed sound metric which is the subjective parameter used in psycoacoustics. According to recent research results, the relation between sound metrics and subjective evaluation is very complex and has nonlinear characteristics. In order to estimate this nonlinear relationship, artificial neural network theory has been applied to derivation of sound quality index for rumbling sound of a passenger car.

• 한국의류학회지
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• 제6권1호
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• pp.61-66
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• 1982

Succeeding to Report 1, to compare folded curtain fabrics with curtain fabrics, the sound pressure level (SPL) of folded curtain fabrics were measured by sound level meter. Transmission coefficient was calculated by the ratio of incidence sound intensity and transmission sound intensity. The relationship between these values and factors (drape coefficient, porosity) relating to the structure of curtain fabrics were investigated experimentally. The following results were obtained: 1. The transmission coefficient by ratio of sound pressure level was lower than that by ratio of sound intensity. 2. In folded curtain fabrics, difference of SPL was smaller and transmission coefficient generally decreased. 3. The relation between the porosity and transmission coefficient of curtain fabrics is given as plus correlation.

• 소음진동
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• 제9권4호
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• pp.693-702
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• 1999

We study the characteristics of airflow and sound noise induced by disk rotation in optical disk drives. The characteristics of airflow around a rotating disk surrounded by various tray structures are numerically investigated using a commercial CFD program and then compared with experimental results. Sound pressure and intensity caused by the fluid-structure interactions in the CD/DVD-ROM drive are measured, and the effect of the ariflow on the sound noise and disk vibration is discussed. In order to reduce airflow-induced noise and vibration around the rotating disk, tray geometry is modified. Both numerical and experimental studies implemented with different tray models show that the improved tray model alters the characteristics of the disk-induced airflow, causing the reduction of the airflow-induced sound level.