• 대한의용생체공학회:의공학회지
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• 제32권1호
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• pp.55-60
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• 2011

Although sound intensity is considered as one of important factors in auditory processing, its neural mechanism in auditory neurons with limited dynamic range of firing rates is still unclear. In this study, we examined the effect of sound intensity adaptation on the change of glucose metabolism in a rat brain using [F-18] micro positron emission tomography (PET) neuroimaging technique. In the experiment, broadband white noise sound was given for 30 minutes after the [F-18]FDG injection in order to explore the functional adaptation of rat brain into the sound intensity levels. Nine rats were scanned with four different sound intensity levels: 40 dB, 60 dB, 80 dB, 100 dB sound pressure level (SPL) for four weeks. When glucose uptake during the adaptation of a high intensity sound level (100 dB SPL) was compared with that during adaptation to a low intensity level (40 dB SPL) in the experiment, the former induced a greater uptake at bilateral cochlear nucleus, superior olivary complexes and inferior colliculi in the auditory pathway. Expectedly, the metabolic activity in those areas linearly increased as the sound intensity level increased. In contrast, significant decrease interestingly occurred in the bilateral auditory cortices: The activities of auditory cortex proportionally decreased with higher sound intensities. It may reflect that the auditory cortex actively down-regulates neural activities when the sound gets louder.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.254-257
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• 2005

Locations and emission characteristics of noise source of rapier loom are important factors greatly. So, noise characteristics of rapier loom were investigated by the noise source identification as a part of experimental methods in this study. To identify the noise sources of the rapier loom sound intensity was measured under machine operation. In addition, frequency spectra of the sound at operator position was measured along with sound intensity to help identify the noise characteristics of the rapier loom. The results indicate that the sound power level occurs along the rapier loom.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.492-499
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• 2014

The objectives of this study was to examine experimentally the microexplosion phenomena of single droplet W/O(water-in-oil) type emulsified fuel. Also, measured the combustion characteristics of single droplet emulsified fuel for microexplosion phenomena in atmospheric pressure condition. The larger quantity of adding water makes microexplosion phenomenon with higher intensity of sound level, because larger water droplet has better coalescence for emulsified fuel. The small quantity of adding water makes puffing with lower sound level intensity. In latter period of extinction, large size droplet of the emulsified fuel breaks down rapidly to small size droplet, and microexplosion phenomenon occurs with multi step combustion.

• 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.

• 말소리와 음성과학
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• 제9권2호
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• pp.119-124
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• 2017

This study investigates how perception of easy sentences varies with prosody pattern, sound intensity, and signal-to-noise ratio(SNR) in young adults with normal hearing who were in their 20's. The results showed that the presence of proper prosody pattern in the sentences increased correct perception rate of the target sentences, and that the lower the intensity and SNR, the lower the sentence perception scores. The results also showed that SNR had a greater effect on the sentence perception scores than sound intensity. There was a significant decrease of perception scores starting at the level of 15 dB and +3 SNR for the sentences with prosody pattern, while starting at the level of 18 dB and +6 SNR for the sentences without prosody pattern, ending up with a very poor perception score as sound intensity and SNR gets lower. There was a significant difference in the perception score of the sentences with prosody pattern between 20 year-old group and 21 year or older group in several listening conditions of sound intensity and SNR.

• 한국음향학회지
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• 제3권1호
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• pp.3-8
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• 1984

By one dimensional acoustic transmission from ground to air, the author has derived the level of sound caused by earthquakes. He has also tried to assign proper values of ground acceleration to the modified mercalli intensity scale and thence earthquake sound level to the intensity scale has been deduced as L\sub M/ = 79.6+6.0M, dB, where M is the earthquake magnitude in the modified Mercalli intensity scale.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.752-760
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• 1993

We research ed on the noise control of a head feeding type combine harvester. It is a kind of combine harvester developed in Japan. And at present, it is used by most Japanese farmer. For a head-feeding type combine harvester it is very difficult to determine the sources of noise because it is a combination of reapers and automatic , threshers and several running parts. However we succeeded in finding out the sound sources of combine harvesters and analyzing their sound by the using sound intensity method. The sound intensity Method is a very up-to-date method to measure and analyze Sound Intensity Levels and sound directions at several measuring point sin a specified area. In this research, first a conventional sound level measurement method is used and secondly the sound intensity method. The first method shows a rather great limitation in allowed exposure duration. The second method shows pin-points the engine itself as being the main source of noise, causing sound flows a ross the operator's seat.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1540-1548
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• 2000

Sound intensity techniques and ODS(Operational Deflection Shape) techniques are applied to identify the acoustic noise source of a hard disk drive and its control system. The sound intensity is used to visualize the noise source locations, and the ODS information to visualize the vibration pattern and to obtain the dynamic characteristics of the noise sources. The measurement systems are customized to accurately measure the sound intensity and ODS distributions of HDD system in space domains as well as frequency domains. The measurement systems for the sound absorption and transmission loss of materials are also used to support the background data for the efficient noise control. Using the visual information of source locations and its dynamic characteristics, the partial noise barrier structure and optimum absorption are designed and its controlled sound power level is proved to be under 3.1 Bel(Idle)/3.3Bel (Seek) which is the lowest level in the disk drive industry.

• 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.

• KIEAE Journal
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• 제9권5호
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• pp.63-68
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• 2009

As with the disappearance of a living room window due to the trend in apartment housing construction that prefers a larger, expanded living room, the sound insulation performance of the balcony window is becoming an important factor to determine the level of indoor noise at an apartment unit. Considering that the indoor noise inside an apartment unit is mandated by law at or below 45dB(A), the balcony window is increasingly assuming an even more important role. Sound insulation performance of the window was measured by examining differences in data involving varying angles of incidence of the sound source as obtained from the same balcony window. Also, acoustic intensity measuring was performed at and around the window to determine its sound insulation quality. Results of measuring on the sound source's angles of incidence indicated that the performance showed some differences in lower frequency ranges, though with no significance. Intensity measuring results showed that the sound insulation performance was reduced near the connection part of the window and the window frame.