• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.5
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• pp.430-436
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• 2011

The purpose of this study is to analyze the vibration and sound generation characteristics of the sandwich panel. Two thick panels were assumed to be separated by a compliant viscoelastic core. The transverse vibration induced by an external impact was analyzed using the Rayleigh-Ritz method. For applying arbitrary boundary condition of the panels, the edges were assumed to be supported by the translational and rotational springs. The beam functions were used as the trial functions. The effect of the boundary condition and viscoelastic core on the resulting vibration characteristics was investigated. The radiated sound power was analyzed using the proposed numerical model and the Rayleigh integral. The dynamic properties of the core and the mass-stiffness-mass resonance frequency had significant influence on the impact sound.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.97-103
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• 2015

The people who are in the noise factory are difficult to hear and recognize about fire and to evacuate quickly when a fire occurs. This study was conducted to analyze workplace's background noise of 31 factories in Incheon and to know the workplace noise level comparing to fire alarm sound level. The measured average noise level was 96.8dB(A). Noise level of measured result was exceeded as 6.8dB(A) comparing to NFSC (National Fire Safety Code) noise level of 90dB. NFPA suggests that when background noise exceeds 85dB or more than that, other methods should be considered to know alarm sound. Also fire alarm sound should exceed more than 15dB(A) comparing to background noise level. Therefore it was concluded that the design of the fire alarm systems should not be applied to the workplace without considering background noise and it needs to be improved with regulations and the systems.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.29 no.1
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• pp.24-33
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• 2010

This paper proposes a technique of sound beamforming that can generate high-directive sound beams, and this paper also presents applications of the proposed algorithm to multi-channel 3D sound systems. The proposed algorithm consists of two phases: first, optimum weights maximizing a sound pressure level ratio between the target and control acoustic regions are designed, and later, the directivity of the pre-designed sound beam is iteratively enhanced by modifying the covariance matrix. The proposed method was evaluated under various situations, and the results showed that it could provide more focused sound beams than the conventional methods.

• Journal of fish pathology
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• v.34 no.2
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• pp.243-248
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• 2021

Offshore wind power generation is an energy generation field that is rapidly developing owing to the increasing demand for clean energy. However, the physiological response of fish to the underwater noise generated during construction or operation of wind turbines is unclear. We confirmed the effects of sound pressures of 125, 135, 145, and 155 dB/µPa, including 140 dB/µPa (the standard sound pressure for noise damage recognition in South Korea), through serum analysis in rock bream (Oplegnathus fasciatus). High mortality induced by reduced immunity through artificial infection after stimulation was confirmed. These results suggest that rock bream is negatively affected by the noise generated during the construction of offshore wind power plants.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.405-408
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• 2012

Recently, Smartphone takes center stage as the next generation game platform, so there's fierce competition between various companies which enter the mobile market. According to Smartphone market is wide, Smart phone App game sound is more widely. This study attempts to analyse the role of sound effects and BGM(background music) during game play or game development, and make a comparison between game play with and without Sound effects, so that to suggest the direction of development of the App game sound for Smartphone and to remind the importance of sound effects and emphasize the necessity of development of the professional game sound.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.454-457
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• 2012

Recently, Smartphone takes center stage as the next generation platform, so there's fierce competition between various companies which enter the mobile market. According to Smartphone market is wide, Smart phone sound is more widely. in this paper, we analyze the necessity of sound desing tailored to the characteristics of mobile sources of sound that can be optimized for the iphone mobile production and mobile sources to meet the need for a sound design and the development direction of the sound, professional sound production suggest the need for.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.550-555
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• 2012

Among the various elements affecting a customer's evaluation of automobile quality, buzz, squeak and rattle(BSR) have been considered to be major factors. In most vehicle manufacturers, the BSR problems are solved by find-fix method with the vehicle road test, mainly due to various excitation sources, complex generation mechanism and subjective response. To systematically tackle the BSR problems in early stage of the vehicle development cycle, these difficulties should be resolved. The aim of the present paper is to characterize the sound quality property of BSR noise that can be used to assess the subjective responses to BSR. The four sound metrics from Zwicker's sound quality parameter are computed for the signals recorded for eight BSR noise source regions localized by using the acoustic-field visualized results. Then, the jury test of BSR noise are performed. On the basis of the computed sound metrics and jury test result is evaluated to represent the harshness of BSR noise. It is expected that the developed BSR measuring system and sound quality properties can be used to reduce the automotive interior BSR noise in terms of subjective levels as well as objective levels.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.11-21
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• 2021

The causes of noise generation according to the classification of indoor spaces are very diverse. Individual happiness is infringed by this noise. In this paper, We tried to visualize the spatial sound characteristics of public places using sound color to express them so that anyone can sympathize. The noise inside a conference room of a medical device company was measured for 100 minutes, and the frequency band was divided into three different types of existing sound pressure expression units. Because the size of the noise is expressed differently depending on the situation, There are cases where there is a difference of opinion between the measurer and the researcher. This noise measurement experiment was conducted, and the sound color was applied to classify it on a log scale considering auditory characteristics. As a result of comparing this with the result expression for different loudness expression units, A specific table in different units yielded almost similar results. In addition, the sound source section for 100 minutes was divided into three analysis sections, the analysis sections were different, and the size of the energy ratio for each analysis section was divided in the form of an envelope. The characteristics of the low-frequency region of the space have a high energy ratio, and the decrease in the energy ratio according to the increase in frequency is constant and regular. You can see that conversations are possible.

• The Journal of the Acoustical Society of Korea
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• v.40 no.2
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• pp.155-160
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• 2021

This paper proposes an automatic method for detecting snore sound, one of the important symptoms of sleep apnea patients. In the proposed method, sound signals generated during sleep are input to detect a sound generation section, and a spectrogram transformed from the detected sound section is applied to a classifier based on a Convolutional Bidirectional Gated Recurrent Unit (CBGRU) with attention mechanism. The applied attention mechanism improved the snoring sound detection performance by extending the CBGRU model to learn discriminative feature representation for the snoring detection. The experimental results show that the proposed snoring detection method improves the accuracy by approximately 3.1 % ~ 5.5 % than existing method.