• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1252-1255
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• 2006

The government has enforced Housing Performance Grade Indication System (Article 21, Paragraph 2 of Housing Act) starting January 2006 for the purpose of giving users in hope of toying an apartment opportunities to select housing based on personal preferences by providing information on housing performance at the time of tenant recruitment announcement as well as securing desirable environment (comfort) by encouraging construction companies to build housing of the indicated performance level. The acoustic performance indication items include three items such as floor impact isolation performance(light weight impact sound, heavy weight impact sound), bathroom noise and insulation performance of boundary walls between households. This paper explains the background, the basis of creation and evaluation method focused on the acoustic environment performance helping for the developer of technique and a staff in charge of construction business who cope with this system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.171-175
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• 2006

Recently, two reverberation rooms were built up of 300mm thick concrete walls in non-parallel pentagonal shape to measure the sound absorption, transmission, radiation, and impact insulation of acoustical materials, panels, doors, etc. Various acoustic tests, including the sound transmission test, were carried out to investigate their acoustic performances. In order to improve the performance, several modifications on these acoustical parameters, such as the acoustic mode, the position of specimen, the formation of diffuse field, the location of sound source, and flanking transmission, have been conducted. Through a series of tests, the reverberation rooms have been effectively improved so that it could perform a variety of acoustic tests with the international standard. And then, it is expected to be very helpful in developing the low noise design technology for ships.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.738-741
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• 2006

Virtual Acoustic Field Simulation System (VFASS) has been developed through soundscape technique research for making comfortable acoustic environment in urban public places. This system could suggest Introducing sounds which are suitable for certain area, Also this system gives certain area vitalities and amenity through with the correspondence to time, temperature, humidity, wind velocity and sunshine of the area. In this paper, Application possibility of VFASS is examined how can be adapted to D University square as a case study.

• 말소리와 음성과학
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• 제1권3호
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• pp.29-37
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• 2009

This paper presents results from speech production experiments on English, Korean, and Hindi that compare variation in the acoustic expression of dissimilar phonological laryngeal contrast in stops conditioned by prosodic prominence. Target stops are analyzed from utterance-initial, -medial, and -final positions, with a variation in contrastive focal accent, from the speech data by six male American English speakers, five male Seoul Korean speakers, and five male Delhi Hindi speakers. The results show that prosodic prominence conditions enhanced distinctiveness between contrastive segments in the three languages. The manner in which prosodic prominence and prosodic phrase structure is marked at the level of segmental variation is, however, found to be language-specific to some extent. In addition, a correlation between the size of the phonological inventory and the corresponding acoustic variation was found but the linear correlation was not strongly supported with the findings in the present study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.383-386
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• 1987

In this paper, a low frequency acoustic microscope system has been built for the purpose of detecting sub-surface defects in materials. 100 won coin, aluminium, ceramics, I.C. are used for experimental and the acoustic microscope is operated in the focused and defocused mode at a frequency of 3 MHz. In experiment, it has shown that acoustic microscope has the resolution of 0.5mm and the defects presented on the surface and near surface of samples are detected by a monitor.

• 한국가구학회지
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• 제11권1호
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• pp.25-29
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• 2000

This study was carried out to analyze the ultrasonic properties of sound board which was glued with various adhesives and to evaluate which adhesive is the best for the acoustic radiation of the musical instrument. The results are as follows: 1. Animal glue is the best adhesive for the sound board with respect to the acoustic radiation ratio of the musical instruments. Epoxy resin and polyvinyl acetate resin are the next group, urea formaldehyde resin and Hot melt are the third group, polychloroprene(CR) resin is the lowest. 2. Epoxy resin, animal glue and Titebond(PVA) give the highest shear strength and the highest wood failure relatively Hot melt and polychloroprene(CR) resin do not meet the standard because of low wood failure.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.861-867
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• 2004

For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.

• 한국안전학회지
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• 제24권6호
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• pp.13-19
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• 2009

The thermoelectric cooling system consisted of the thermoelectric module, a heat sink and a cooling fan, respectively. Also, the piezoelectric actuator was applied to improve the performance of thermoelectric cooling system and investigate the heat transfer phenomenon. The temperature distribution of test section was measured to investigate cooling characteristics of thermoelectric cooling system. The flow phenomenon of test section was visualized using visualization device. When the piezoelectric actuator was applied to the heat transfer process of thermoelectric cooling system, acoustic streaming was occurred in test section. The acoustic streaming was occurred forced convection flow, and was regularly formed the temperature distribution in test section. The results clearly show that the acoustic streaming is one of the prime effects to enhance the convection heat transfer and can enhance the performance of thermoelectric cooling system.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.744-750
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• 2001

Higher directivity acoustic transducer using the self-demodulation effect was fabricated. The structure of transducer was designed such as dimension and support type of the piezoelectric element, the vibrating metal plate, and the housing case. Based on the design, the transducer was fabricated and measured its acoustic characteristics. Also, AM modulated driving circuit was designed for using the self-demodulation effect. The piezoelectric sounder with 200kHz resonant frequency and 20kHz bandwidth was designed by considering the sharp directivity and the sound pressure. The design and fabrication method worked in this study can be utilized in development of various speakers with higher directivity and broader bandwidth.

• The Journal of the Acoustical Society of Korea
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• 제18권2E호
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• pp.45-52
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• 1999

This paper presents the integrated speech enhancement system for hands-free mobile communication. The proposed integrated system incorporates both acoustic echo cancellation and engine noise reduction device to provide signal enhancement of desired speech signal from the echoed plus noisy environments. To implement the system, a delayless subband adaptive structure is used for acoustic echo cancellation operation. The NLMS based adaptive noise canceller then applied to the residual echo removed noisy signal to achieve the selective engine noise attenuation in dominant frequency component. Two sets of computer simulations are conducted to demonstrate the effectiveness of the system; one for the fixed acoustical environment condition, the other for the robustness of the system in which, more realistic situation, the acoustic transmission environment change. Simulation results confirm the system performance of 20-25dB ERLE in acoustic echo cancellation and 9-19 dB engine noise attenuation in dominant frequency component for both cases.