• Title/Summary/Keyword: vibration and sound

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A Study on Prediction of vibration and Sound Radiation by Plate With Four Edges Clamped (네 변이 고정된 평판의 진동 및 방사 소음 예측에 관한 연구)

  • 심현진;이정윤;오재응
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.743-747
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    • 2003
  • In recent years, several studies of the practical application of active sound and vibration control have been developed to plate to plate response with various boundary conditions. This study considers vibration and sound radiation for the clamped rectangular plate. The radiation of a sound from rectangular plate can be calculated that the velocity of a vibrating plate is analyzed. The vibration formulation is based on a variation method for the vibration of the plate, and assumes no damping, no fluid loading of the structure. And the plate is exited by harmonic point force. The radiation of sound from plate is analyzed in the far field, and is calculated from the Rayleigh integral. The prediction results of vibration and sound level have proved with FEM or BEM.

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Floor Impact Sound and Vibration Characteristics Affected by the Compressive Strength of Concrete (콘크리트 슬래브 압축강도에 따른 바닥충격진동 및 소음특성)

  • Jeong, Jeong-Ho;Yoo, Seung-Yup;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.796-799
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    • 2005
  • In 2005, a regulation on the heavy-weight impact sound was released, which restricted concrete slab thickness of standard floor to 210mm. To reduce heavy-weight impact sound, damping materials and structural reinforcement system have been proposed. In this study, the effect of compressive strength on the heavy-weight impact vibration and sound were investigated. FEM analysis was conducted for the 34PY apartment with different concrete strength (210, 350, 420kg/cm$^2$). In addition, apartment floors with different concrete strength were constructed and the floor impact vibration and sound were measured. Results of FEM analysis and measurement show that the resonance frequency of concrete slab was increased by the increment of concrete strength. However, floor impact sound pressure level did not decrease because the nor impact vibration and sound pressure level in 63Hz band increased.

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Sound manipulation: Theory and Applications (음장 제어의 이론과 그 적용)

  • Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.468-471
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    • 2008
  • Sound manipulation is to control sound field using multiple sound sources for appropriate purposes. In linear acoustics, a sound can be constructed by superimposing several fundamental sound fields such as a planewave and sphere shape sound field. That is how we manipulate sound field. In this paper, we introduce the theory of sound manipulation and its applications from the examples of the generation of fundamental sound field: a circle, a ring shape sound field and a planewave field.

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Fiber Optic Sensor Design for the Monitoring of Structural Sound and Vibration (구조물 음향진동 모니터링을 위한 광섬유 센서 설계)

  • Lee, Jong-Kil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.81-84
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    • 2007
  • In this paper, fiber optic sound and vibration monitoring sensor which is latticed shape structure based on Sagnac interferometer is fabricated and tested in laboratory conditions. To detect external vibrations surface mounted fibers on the latticed steel wire fence with a dimension of 170cm by 180cm is used. To detect external sound frequency the tightened fiber optic itself wire netting fence with a dimension of 50cm by 50cm is used. Experiments for the detection of the excited vibration and sound signals were performed. A small vibrator induced external vibration signal and it is applied to the latticed structure in the range of 100Hz to several kHz. External sound signal applied to the fiber optic sensor net using non-directional sound speaker. The detected optical signals were compared and analyzed to the detected both accelerometer and microphone signals in the time and frequency domain. Based on the experimental results, distributed fiber optic sensor using Sagnac interferometer detected effectively external vibration and sound signal and had a good performance. This system can be expanded to the monitoring of a significant system and to the structural health monitoring system.

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Vibration and Sound Characteristic of the Chun-cheon Citizen's Bell (춘천시민의 종의 진동 및 음향 특성)

  • Kim, Seok-Hyun;Kim, Tae-Hyung;Kim, Yun-Ho;Han, Young-Ho
    • Journal of Industrial Technology
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    • v.26 no.A
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    • pp.81-88
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    • 2006
  • The Chun-cheon Citizen's Bell was cast in memory of hosting the 2010 world leasure conference and a striking ceremony was held at the city hall on December 31, 2005. In this study, vibration and sound of the bell are measured and the property of the magnificent sound of the bell is scientifically investigated. Frequency components making the sound are identified and how the frequency components decrease with time is observed using waterfall plot(3-dimensional frequency spectrum). Beat characteristics of the hum(1st frequency) and the fundamental(2nd frequency)are examined by experiment. Directivity of the sound radiation of the bell is examined by measuring the vibration and sound in several directions. Duration of the vibration and the sound is estimated using damping ratio.

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A Study on Reduction of Sound Noise Induced by Disk Rotation in Optical Disk Drives (광 디스크 드라이브의 공력소음 감소에 관한 연구)

  • 송인상;박건순;최학현;김수경;이승엽
    • Journal of KSNVE
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    • v.9 no.4
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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.

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New Development of Two-dimensional Sound Quality Index for Brand Sound in Passenger Cars (승용차 브랜드 사운드를 위한 이차원 음질 인덱스 개발)

  • Jo, Byoung-Ok;Park, Dong-Chul;Lee, Min-Sub;Jung, Seung-Gyoon;Lee, Sang-Kwon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.5 s.110
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    • pp.457-469
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    • 2006
  • In automotive engineering, the brand sound is one of the important advantage strategies in a car company. For the design of brand sound, the selection of descriptive word for a car sound is one of major works in automotive sound quality research. In this paper, booming and rumbling sound, which are professional words used by sound and vibration engineers are used for the design of brand sound. We employed sound quality metrics, which are used in the psychoacoustics. By most research results, the relationship between subjective evaluations and sound quality metrics has nonlinear characteristics. In order to correlate these subjective evaluations with sound quality metrics, the artificial neural network technology has been applied to two-dimensional sound quality index for a passenger car. These indexes are used for 46 passenger cars, which are samples of the famous cars around the world. Also a preference evaluation for car sound was carried out by sound and vibration engineers. We coupled this preference with booming and rumbling sounds by using artificial neural network. In future, the two dimensional sound and preference index will be very useful to develop brand sound in passenger cars.

Study on the Development of Integrated Vibration and Sound Generator (휴대폰용 일체형 음향 및 진동 발생장치 개발을 위한 연구)

  • 신태명;안진철
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.11
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    • pp.875-881
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    • 2003
  • The received signal of a mobile phone is normally sensed through two independent means which are the sound generation of a speaker and vibration generation of a vibration motor. As an improvement scheme to meet the consumer's demand on weight reduction and miniaturization of a mobile phone, the design and development of an integrated vibration and sound generating device are performed in this research. To this purpose, the optimal shapes of the voice coil. the permanent magnet and the vibration plate are designed, and the excitation force applied to the vibration system of the new device is estimated and verified through theoretical analyses, computer simulation, and experiments using an expanded model. In addition, vibration performance comparison of the device with the existing vibration motor is performed, and from the overall process, therefore, the method and procedure for the vibration performance analysis of the integrated vibration and sound generating device are established.

The Characteristics of Heavy-weight Impact Sound and Vibration According to the Change of Impact Force in An Apartment Building (충격력 변화에 따른 공동주택의 중량 충격음 및 진동 특성)

  • 서상호;전진용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.304-307
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    • 2004
  • To reduce the structure-born sound by floor impact source in an apartment building, it is necessary to identify the relationship between floor impact sound and vibration. Various impact sources which were made by a bang machine and an impact ball were used for measurement of impact sound and vibration. The experimental results show that the linear relationship between floor impact sound and vibration was in existence despite of various floor impact sources.

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Speech Intelligibility Analysis on the Vibration Sound of the Glass Window of a Conference Room (회의실 유리창 진동음의 음성 명료도 분석)

  • Kim, Hee-Dong;Kim, Yoon-Ho;Kim, Seock-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.4 s.121
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    • pp.363-369
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    • 2007
  • The purpose of the study is to obtain acoustical information to prevent eavesdropping of the glass window. Speech intelligibility was investigated on the vibration sound detected from the glass window of a conference room. Objective test using speech transmission index(STI) was performed to estimate quantitatively the speech intelligibility. STI was determined based on tile modulation transfer function(MTF) of the room-glass window system. Using Maximum Length Sequency(MLS) signal as a sound source, impulse responses of the glass window and MTF were determined by signals from accelerometers and laser doppler vibrometer. Finally, speech intelligibility of the interior sound and window vibration were compared under different sound pressure levels and amplifier gains to confirm the effect of measurement condition on the speech intelligibility.