• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.698-704
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• 2022

In this paper, the radiated aerodynamic noise generated from sound sources of a nozzle inflow is quantitatively investigated and compared with experimental results of externally radiated noise. A high-resolution unsteady compressible Large Eddy Simulation (LES) technique is used to accurately predict the internal and external flow of three types of nozzle shape. Through using the vortex sound source for sound sources, the geometry of nozzle neck is identified as most significant aerodynamic noise sources. For validation of quantitative analysis, the vortex sound source intensity of internal nozzle flow is compared with results of external radiated noise of calculation and experiment.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.298-304
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• 2010

Recently, the audible sound level of power transformer has been reduced due to development of new material and enhancement of manufacturing technology. There is lack of research on the audible sound of winding and cooling fan because the research on reduction of audible sound is concentrated on the core sound. Therefore this paper describes 3 kinds(core, winding and cooling fan) of transformer sound source. Also this paper analyzes the effect of load sound and cooling fan sound on the total transformer sounds. As the results, total sound level of 79dBA class transformer rises 0.2～0.3dB due to effect of load sound and rises 2.1～3.5dB due to effect of cooling fan sound. Also, total sound level of 55dBA class transformer rises 2.3～2.9dB due to effect of load sound and rises 1.9～3.5dB due to effect of cooling fan sound.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.814-819
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• 2004

When we evaluate sound, there are various methods for noise such as A-weighted SPL(sound pressure level), NC(noise criteria), NR(noise rating) and SIL(speech interference level) etc. however, it is not sufficient for the sounds supplied to public places used in soundscape design. Consequently it is needed to develop the tool for evaluating the good acoustical environment and futhermore quantifying the effect of improvement by supplying sound sources. In this study, it was tried to analyse the sound sources applied for soundscape design using sound quality parameters. The sound sources used were natural sound artificial sound. For the sound quality parameters, Loudness(L), Sharpness(S), Fluctuation strength(FL), Tonality(T), Roughness(R), Unbiased Annoyance(UA) were used and sound quality values were compared both natural and artificial sounds, depending on the convolution of sound sources with background noise, the duration, the frequency contents and the SPL. As a result, the values of L and UA have shown to be changed comparing to the other parameters, and it is necessary to analyse the correlation with subjects' responses.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1018-1024
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• 2010

The printer noise consists of the noise of the various components and parts such as motor, fan and solenoid. And the human's printing sound recognition shows various aspects when the printer starts to print papers because the components operate at the same time. Especially, printers are usually installed in the quiet office room. Therefore the printing noise is related to its competitiveness in the market. The importance of the printer sound qualities is increasing and it is necessary to develop the sound quality evaluation system, so it is a key point to identify the noise source of the printer and develop the sound quality index to each component. By using this evaluation system, it is possible to evaluate the sound quality of a prototype printer compared to the already existing one. In this paper, the printer sound quality evaluation system was developed by the following steps. Firstly, the signal processing method was applied to the recorded printing sound to identity and split the noise of components. Secondly, the MLR(multiple linear regression) method and the psychoacoustics were used to develop the sound quality index. Finally, the improvement of the printer sound quality is possible by using the result of the MLR and the path analysis. The output of this research will be applied to the development of a new printer.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.239-252
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• 1993

This study was done to analyze phonetic dysfunction and the effect of orthognathic surgery to phonation in the patients of mandibular prognathism. 20 persons were chosen as normal group and 20 patients of mandibular prognathism as abnormal for this study. 5 vowel sounds-'ㅏ(a)', 'ㅔ(e)', 'ㅣ(i)', 'ㅗ(o)', 'ㅜ(u)' and 14 consonant sounds-'ㄱ(g)', "ㄴ(n), 'ㄷ(d)', 'ㄹ(l)', 'ㅁ(m)', 'ㅂ(b)', 'ㅅ(s)', 'ㅇ(ng)', 'ㅈ(j)', 'ㅊ(ch)', 'ㅋ(k)', 'ㅌ(t)', 'ㅍ(p)', 'ㅎ(h)', were checked. We recorded these sounds in the period of preopration, postop. 12 months, postop. 24 months. A Formant ratio and a length of consonant time were studied with discriminant analysis. As a result of the study, the following conclusion were gained. 1. As a result of the analysis on vowel dysfunction patiensts of mandibular prognathism, more than 80% of men patients showed the dysfunction in prelingual sound 'ㅔ(e)' and 'ㅣ(i)'. More than 70% of women patients showed the dysfunction in all vowel. 2. One year later from the orthognathic surgery, men patients showed a marked improvement in 'ㅏ(a)'. The next were 'ㅗ(o)', 'ㅜ(u)' and 'ㅣ(i)'. Women patients showed a marked improvement in 'ㅜ(u)'. 3. Two year later from the orthognathic surgery, men patients showed a marked improvement in prelingual sound 'ㅔ(e)' and postlingual sound 'ㅗ(o)'. Women patients showed a marked improvement in 'ㅏ(a)'. More than 20% of patients showed the phonetic improvement compared with the condition of the postop. 12 months. 4. As a result of the analysis on consonant dysfunction patient of mandibular prognathism. more than 80% of men patients showed the dysfunction in lingual sound 'ㅅ(s)'. Most women patients showed the dysfunction in labial sound 'ㅁ(m)' and lingual sound 'ㄴ(n)'. More than 50% of patients showed the dysfunction in labial sound and lingual sound. 5. One year later from the orthognathic surgery. men patients showed a complete improvement in hard palatal sound 'ㅈ(j)'. The next were labial sound 'ㅂ(b)', lingual sound 'ㅅ(s)', soft palatal sound 'ㄱ(g)' and 'ㅋ(k)'. Women patients showed a marked improvement in soft palatal sound 'ㅇ(ng)' and 'ㄱ(g)'. 6. Two year later from the orthognathic surgery, all patients showed remarkable improvement in consonant sounds. except for labial sound 'ㅁ(m)', 'ㅍ(p)' and lingual sound 'ㄴ(n)'. The improvement ratio was increased as the time was going on compared with the condition of postop 12 months.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3
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• pp.129-136
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• 2006

For the environmental noise assessments. A weighted equivalent noise level (LeqA) is used to measure the time varying environmental noise. However, it is not appropriately reflect various environmental noise features and human emotions. The human perception of the noise is affected largely by the psychoacoustic characteristics of noise as well as the sound pressure level In this study, the effective factors of noise qualify are analyzed using the subjective assessment and statistical analysis of environmental noise, such as road traffic noise. construction site noise, noise in daily living. and other. The analysis methodology is composed to three steps as follows : firstly, the values of the sound qualify metrics of various noise sources were analyzed. And to classify the noise sources, we conducted a cluster analysis using sound quality metrics. Secondly, subjective jury testing was carried out using the methods of paired comparisons and semantic differential. Finally, the correlation between the subjective parameters and the noise quality metrics were analyzed. As a result. the human perception characteristics of the various environmental noise are described in some physical parameters of the noise qualify metrics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.152-157
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• 2008

Enclosure is widely used for the sound insulation in a ship. But it is very difficult to estimate the sound insertion loss for the enclosure because the sound field between the enclosure and the machine is so complex. Therefore, it is usually estimated experimentally. In this research, sound insertion loss of the enclosure is estimated by theory assuming that the sound field in the enclosure is reverberation field. And the results from the theory are compared to those from the experiment.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.101-105
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• 2020

In this study, we are going to discuss the role of sound, which exists as the background of a movie scene, and the relationship between seeing and hearing. In order to analyze the form in which the scene and sound are matched, the visual content of the image must be analyzed first. In this study, we analyzed Stanley Kubrick's film . Generally, there are both visual and auditory features in the scene of the movie. In some cases, the sound is emphasized more than the scene, and the scene is emphasized more than the sound. In particular, the sound in movies enables a wider imagination and a three-dimensional experience. Images and sounds will have different meanings and effects depending on the purpose of use. By analyzing the correlation between visual scene and auditory sound based on the role sound plays in the film in this study, we would like to confirm that sound is one essential element that has the role of equivalent and independent expression, not the role of assisting images.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.675-680
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• 1997

The object of this study is the numerical analysis about the sound pressure distribution in reverberation rooms. In order to obtain the effect of the boundary conditions of the wall, the sound field was computed for various absorption coefficients and impedances. And the effect of the room shape was investigated by dealing with pentagonal type as well as the rectangular type. In addition an experiment was performed for the sound pressure distribution in a reverberation room and the result was compared with the analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1036-1041
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• 2003

Non-destruction examinations are required in medical sciences and various engineering now. We wish to emulate the examinations in very simplified experiments. It is an educational program. We show a neural network analysis to predict the locations of a sound-source or a body irradiated by sound-waves in audio-region. The sound is an interest flux, and it enables to clear local-structures in a non-transparent space. However, the sound-propagation equations are not solved easily, therefore, we consider to adopt multi-layer neural-networks instead of the direct solutions. We used detected intensities and coordinates for input data and teaching data. A neural network learned them. The neural-network analysis decomposed the distance of 50cm. The resolution is rather rough; however, it is caused by the limitation of our equipments. Since there is no problem in the neural network processing, if we could revise experiments, then, progress of the resolution would be got. Thus, the proposed method functioned as an educational and simplified non-destruction examination.