• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.987-990
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• 2007

The accuracy of sound strength (G) measurement method in ISO 3382 has been questioned. One of the main reason is the difficulty in measuring a reference sound level in an anechoic chamber with the same set-up which was applied for the actual hall measurements. In the present paper, an in-situ measurement method for G was proposed by investigating the present G measurement method shown in ISO 3382. In addition, the sound radiation characteristics of typical omnidirectional loudspeakers were investigated and Phi (O) of auto correlation function (ACF) parameters was also calculated from an actual music excerpt to characterize the sound energy distribution in concert halls.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.830-839
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• 2008

This study is designed to manufacture the upgraded sound absorption concrete by using foamed concrete by using artificial light weight aggregate which raises the continuous void ratio to increase the sound absorption ratio and improve the strength. In manufacturing the sound absorption block, the pre-foaming form is applied to generate continuous voids, controlling the density by the addition of bubbles. It is general that the more porosity creates, the weaker strength becomes. Each of specimens are used for this experiment and measured their absorption ratio to examine the absorption property depending on frequency. As a results of experiment, it is evaluated that the absorption capacity of the sound absorption block has relation to compression strength and surface shape.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.72-78
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• 2013

Compacted graphite iron 340 was carried out the heat treatment from 873 to 1,273 K. Compacted graphite iron 340 was evaluated relationship between the sound velocity, the attenuation coefficient and the tensile strength. The obtained results are as following. The signal strength of C scan images were weak according to increasing of heat treatment temperature and time. The amplitude of A scan and B scan was also low. This can be cause that the graphite was grown into the type of vermicular, and the many of grain boundary with ultrasound scattering were increase. The sound velocity was depend upon the heat treatment temperature and time, the attenuation coefficient had nothing to do with the temperature and time. The higher the heat treatment temperature, the tensile strength and the sound velocity were decreased. However, the tensile strength was proportional to the sound velocity. The higher tensile strength, the faster the sound velocity.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.489-492
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• 2003

The results of an experiment on the sound absorption of the porous concrete and its influence on the compressive strength are reported in this paper. Two different sizes of coarse aggregate of 5~13, 13~20mm, and the design void ratio of 20, 25 and 30 percent for a given size of aggregate were used. In the compressive strength, an aggregate of the size of 5~13mm is much higher strength than that of the 13~20mm, In the sound absorption experiment, the size of aggregate of 5~l0mm is much higher sound absorption than that of the 13~20mm. The sound absorption ratio was increased as the design void ratio. As a result, Porous concrete sufficiently have the performance of sound absorption.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.276-277
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• 2012

This study was carried out in the laboratory of the reverberation. A total of six specimens were fabricated depending on the thickness and strength. Floor impact sound insulation performance was measured in 1/3 octave band center frequency. The results of this study are as follows. Although some differences in the frequency band, the result of evaluating the weight impact sound blocking performance as the thickness increases, the floor impact sound insulation performance is improved. In addition, to increase the strength of the slab, even if the block impact sound performance is improved.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.935-940
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• 2001

This study search for absorbing sound and exhaust-gas which aims to manufacture continuous void by using clay and foam, the surface of materials is covered with $TiO_{2}$ powder as heat treatment. According to the results of the experiment, the increase of thickness of manufactured sound absorbing materials caused the increase of absorption rate in the range of low and middle sound and thus it can be an important factor of improving absorption rate. Sound absorbing materials could satisfy 70% of the average of sound absorption ratio in 7cm thickness. Also, the manufactured sound absorbing materials is covered with $TiO_{2}$ showed an excellency in the clarification of exhaust-gas under ultraviolet rays treatment when 70% of removal rate and about 10% of generation rate of $NO_{2}$ is settled by the flow of 2 $\ell$/min NO gas. Especially, manufactured sound absorbing materials could improve compressive strength of continuos porous concrete. in the case of 7% bubble addition, when the substitution rate of coagulator was 30% and 20%, compressive strength was 45kgf/$cm^{2}$ and 65kgf/$cm^{2}$ respectively. As the substitution rate of coagulator reducing, compressive strength increased after preforming burnt clay.

• Journal of the Korean GEO-environmental Society
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• v.19 no.8
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• pp.5-10
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• 2018

This study provides a method to assess the compressive strength of granitic gneiss using total sound signal energy, which is calculated from the signal of sound pressure measured when an object impacts on rock surface, and its results. For this purpose, many test specimens of granitic gneiss were prepared. Each specimen was impacted using a devised device (impacting a specimen by an initial rotating free falling and following repetitive rebound actions) and all sound pressures were measured as a signal over time. The sound signal was accumulated over time (called total sound signal energy) for each specimen of granitic gneiss and it was compared with the directly measured compressive strength of the specimen. The comparison showed that the total sound signal energy was directly proportional to the measured compressive strength, and with this result the compressive strength of granitic gneiss can be reliably assessed by an estimation equation of total sound signal energy. Furthermore, from the study results it is clearly believed that the compressive strength of other rocks and concrete can be assessed nondestructively using the total sound signal energy.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.485-488
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• 2003

The results of an experiment on the sound absorption of the porous concrete using recycled aggregates and its influence on the compressive strength are reported in this paper. The content of recycled aggregate of 0, 10, 30, 50 and 70%, and the design void ratio of 30 percent for a given size of aggregate were used. In the compressive strength, an aggregate of the size of 5~13mm is much higher strength than that of the 13~20mm, In sound absorption experiment, the sound absorption ratio was is subjected to decreased as the content of recycled aggregates was increased. As a result, Porous concrete using recycled aggregates and by-products sufficiently have the performance of sound absorption.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.3 no.1
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• pp.56-62
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• 2000

The trends of recent passenger ships are becoming speedy and luxury style to enhance comfortableness in cabin. In order to meet these trend, ship designer has to improve the sound quality as well as to reduce the sound pressure level in cabins. In this paper, the trend of noise and sound quality of real high-speed coastal passenger ships are measured and analyzed, while running on their regular courses. The sound quality parameters such as loudness, roughness, fluctuation strength, and sharpness are evaluated by Zwicker loudness calculation. In addition, we try to find sensitive critical frequency band for the improving sound quality by using signal editing. Finally, the expected effective design methods are proposed to designer for the improving sound quality of passenger ships.