• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.579-585
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• 2002

This study has measured and evaluated the sound insulation of building elements of the hotel near airport. That measurement was made in both the actual site and laboratory. The differences of sound insulation performance in between granite and double glass were measured. Moreover, the difference of sound insulation was analyzed. For the measurement, this study has tried several methodologies, and analyzed the differences respectively. The results from this analysis were applied to produce a design guides for sound insulation to prevent external noise and to make more silent indoor space which satisfied the standard rate of noise.

• Phonetics and Speech Sciences
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• v.14 no.2
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• pp.87-99
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• 2022

A review regarding indicators used in Korean research is needed to develop a diagnostic marker system for Korean children with speech sound disorders (SSD). This literature review examined the research conducted to reveal the characteristics of children with SSD of unknown origin in Korea. The researchers in Korea used diverse variables as indicators to identify the natures of children with SSD. These included indicators related to external characteristics of speech sound and comorbid features other than external aspects of speech sound. The attention has been focused on specific indicators so far. This result implies that some indicators may still require closer study in various aspects due to their influence, and some may require more attention due to the limited number of research. This article argues that more research is necessary to comprehensively describe the unique characteristics of children with SSD of unknown origin and suggests a direction for future research regarding diagnostic markers and subtype classification of SSD. It also proposes potential diagnostic markers and a set of assessments for the subtype classification of SSD.

• Journal of KSNVE
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• v.3 no.2
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• pp.169-178
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• 1993

Internal & External duct acoustic fields are calculated by using a finite element method. The geometry is assumed as an axisymmetric duct. External acoustic field; outside the duct, and combined internal & external acoustic fields are solved. For both cases a far field's nonreflecting boundary condition is enforced by using a wave envelope element, which is a kind of finite element. First, a pulsating sphere and an oscillating sphere problem are calculated to verify the external problems, and the results are compared with exact solutions. When the wave envelope element is applied at the far boundary, the calculated finite element solutions show good agreements with the exact solutions. Secondly, the combined internal & external duct acoustic fields are calculated and visualized when monopole sources are distributed inside the duct. It is observed that the directivity of sound intensity outside the duct is beaming toward the axis for high frequency sources.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.41-50
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• 1998

The detemination of sound pressure radiated from peoriodic plate structures is fundamental in the estimation of noise levels in aircraft fuselages and ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal symmetric beams subjected to a sinusoidally time varying point load is developed. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Structural damping is included in both plate and beam materials. A space harmonic series representation of the spatial variables is used in conjunction with the Fourier transform to find the sound pressure in terms of harmonic coefficients. From this theoretical model. the sound pressure levels on axis in a semi-infinite fluid (water) bounded by the plate with the variation in the locations of an external time harmonic point force on the plate can be calculated efficiently using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numerical package.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.878-881
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• 2003

To acquire an appointed speaker's clear voice signal from inspect-camera, picture-conference or hands free microphone eliminating interference noises needs to be preceded speaker's position automatically. Presumption of sound source position's basic algorithm is about measuring TDOA(Time Difference Of Arrival) from reaching same signals between two microphones. This main project uses ADF(Adaptive Delay Filter) [4] and CPS(Cross Power Spectrum) [5] which are one of the most important analysis of TDOA. From these analysis this project proposes presumption of real time sound source position and improved model NI-ADF which makes possible to presume both directions of sound source position. NI-ADF noticed that if auditory sense of humankind reaches above to some specified level in specified frequency, it will accept sound through activated nerve. NI-ADF also proposes practicable algorithm, the presumption of real time sound source position including both directions, that when microphone loads to some specified system, it will use sounds level difference from external system related to sounds of diffraction phenomenon. In accordance with the project, when existing both direction adaptation filter's algorithm measures sound source, it increases more than twice number by measuring one way. Preserving this weak point, this project proposes improved algorithm to presume real time in both directions.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.323-337
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• 2009

This paper researched the adiabatic characteristic, safety and sound insulation characteristic of rolling stock window pane type and transition process of korean train vehicle window glass, and also including investigating a hereafter course of development. The window pane have provided the romantic feeling and the external scenery of train travel to the passenger in period of korea 110 year railway history. From the adiabatic viewpoint, this paper reviewed heat conductivity(U-value) and solar factor according to window pane type, including the safety and sound transmission loss of window pane.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.225-229
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• 2011

The aluminum composite panel are widely used for the external materials of high rise building because of well insulation of heat and sound and improved Constructability. However, the polyethylene in main material of the aluminum composite panel shows weakness in thermal and fire resistances. For this reason, flame is spread more quickly when the fire break out. Therefore, the potentiality of fire spread to the exterior wall is high due to difficulty of early extinguishment and effect of external air. In this study, numerical investigation was performed by using FDS program for flame spread characteristics with various external air velocity and direction in ten-story building with the aluminum composite external materials. As a result, the flame spread velocity is 0.134m/s and it takes 224 seconds for flames to spread to the 10th floor without external air velocity. however, the flame spread velocity decreases 40% and it takes 348 seconds for flames to spread to the 10th floor when external air velocity is 2.5 m/s. and air direction is little effect compared to air velocity.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.302-311
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• 2022

Sound barrier walls are one of the most effective alternatives for reducing environmental noise on roads and railways in the city center. The insertion loss of the sound barrier against road traffic noise is the sum of the sound transmission loss, sound absorption loss, and sound energy reduction due to the diffraction attenuation of the sound barrier. The sound transmission loss of the sound barrier is one of the important factors that determine the insertion loss of the sound barrier and is a basic indicator that determines the performance of the sound barrier. Nevertheless, there is not a separate standard in Korea for measuring the acoustic transmission loss of sound barrier panels. There are only a few conditions in KS F 4770 series that stipulates on the general material of sound barrier panels. This thesis examines the necessity of the acoustic transmission loss measurement and evaluation standards of sound barrier walls, and seeks a measurement method in a free sound field (anechoic chamber) sound receiving room considering the characteristics of sound barrier walls installed in external spaces, unlike indoor building materials. In addition, a single number evaluation method using a reference spectrum was proposed so that the sound insulation effect according to various installation places such as roadside or railroad side can be easily displayed.

• The Journal of the Acoustical Society of Korea
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• v.34 no.5
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• pp.351-359
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• 2015

Typical underwater acoustic transducers detect only the magnitude of an acoustic pressure and they have the limitation of not being able to recognize the direction of the sound signal. Hence, the authors of this paper proposed a new vector sensor structure based on Tonpilz transducers that could detect both the magnitude and the direction of a sound pressure. In the proposed structure, the piezoceramic ring was divided into four segments, and proper combination of the output voltages of the segments in response to the external sound pressure could provide the information on the orientation of the sound source. In this paper, a Tonpilz transducer has been fabricated to have the proposed structure and its characteristics has been measured to confirm the validity of the proposed structure.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.214-220
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• 1998

The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise levels in aircraft fuselages and ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model for prediction the sound radiated by a vibration plate stiffened by periodically spaced orthogonal symmetric beams subjected to a sinusoidally time varying point load is developed. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Structural damping is included in both plate and beam materials. From this theoretical model, the sound pressure levels on axis in a semi-infinite fluid(water) bounded by the plate with the variation in the loactions of an external using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numerical package.