• Proceedings of the Acoustical Society of Korea Conference
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• 1998.08a
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• pp.136-141
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• 1998

In order to enhance the performance of a CELP coder at low bit rates, it would be necessary to make the CELP excitation have the peaky pulse characteristic. In this paper we introduce an excitation signal with peaky pulse characteristic. It is obtained by using a two-tap pitch predictor. Samples of the signal have different gains according to their amplitudes by the predictor. In voiced sound the signal has the desirable peaky pulse characteristic, and its periodicity is well reproduced. Particularly, peaky pulses at voiced onset and a burst of plosive sound are clearly reconstructed.

• Journal of the Korean housing association
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• v.24 no.2
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• pp.97-104
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• 2013

This study involves 2 newly built apartment houses which are A with 23 floors as 150 mm slab width and B with 16 floors as 180 mm slab width. The impact was added by tapping and bang machine at the middle floor level of these 2 apartments and the test was arranged in terms of the characteristic of vibration and sound level which transferred to upper or down floors. As a result, impact floor shows the highest value in terms of both sound and vibration level and followed was at down floor of the Impact floor. Also, blocking function for the lightweight and heavyweight floor impact sound level was tested for each room of the apartment A and B including living room, main room, room 1 and 2. As a result, sound blocking function of B apartment was better than that of A and the function was getting worse when the room size is getting smaller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.364-369
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• 2012

The vehicle sound classified into driving sound due to power-train, operating sound due to electric motor like sunroof, door lock and electronic sound. These vehicle sound has various features depend on the characteristic of sound that user required. And it based on cultural and regional difference of user. In this study, the user required vehicle sound characteristics for luxury sedan was investigated in overall viewpoint. And virtual target sound was developed through the result of user preference investigation. Next, Jury test was carried out in Germany, USA and Korea for evaluating the target sound. And the regional and individual difference of preference was analyzed through the result of jury test. This result of research will be contributed to design of vehicle sound quality and target sound setting.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.247-254
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• 2008

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS(styrofoam), recycled urethane types, EVA(ethylene vinylacetate) foam rubber, foam PE(polyethylene). glass fiber & rock wool, recycled tire, foam polypropylene. compressed polyester, and other synthetic materials. In this study, we tested dynamic stiffness of resilient material and floor impact sound reduction characteristic to a lot of kinds of resilient materials. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And the test showed that the amount of the heavy-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. The dynamic stiffness looked like between other resilient materials, a similar to the amount of the heavy-weight impact sound reduction was shown.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.491-496
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• 2004

The paper describes measurement techniques for an acoustic transfer characteristic of ship's bridge stimulated by a whistle sound The response sounds, according to the opening-shutting conditions of bridge doors for Training Ship ‘SAENURI’, are measured by B＆K 2260D equipment, and then the frequency responses are extracted by B＆K 7830 software. To evaluate the measured transfer characteristic, the 128th order FIR (Finite Impulse Response) filters, containing the different frequency characteristics, are constructed based on the frequency sampling-based design method Using evaluation indexes with six scales, psychological assessments by five subjects are carried out with test sounds which are obtained from convolving the source signal with FIR filters. As results of tests, the test sounds gives $A_S$ 3.3∼4.7 which means the psychological sense of ‘it is almost similar sound as original ones in a real world’, and thus it is clearly seen that the proposed method can be used for the measurement of an acoustic transfer characteristic of ship’s bridge.

• Journal of KSNVE
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• v.11 no.3
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• pp.471-476
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• 2001

This paper focuses on the numerical prediction of airflow-induced sound in DVD drives. As a first step, computational fluid dynamics (CFD) is conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. Acoustic analogy based on Ffowcs Wi1liams-Hawkings (FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. The strength of sound pressure revel with respect to rotating speed is discussed to meet upfront demand on the high fidelity product development. The present study also focuses on the noise directivity and examines how much the sound noise is sensitive to change in rotating speed. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, so it generates different sound noise Patterns compared with those in the near field.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.437-439
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• 2006

Actually, The present traffic accident detection system is subsisting limitation of accurate distinction under the crowded condition at intersection because the system defend upon mainly the image information at intersection and digital image processing techniques nearly all. To complement this insufficiency, this article aims to estimate the level of present technology and a realistic possibility by analyzing the acoustic characteristic of crash sound that we have to investigate for improvement of traffic accident detection rate at intersection. The skid sound of traffic accident is showed the special pattern at 1[kHz])${\sim}$3[kHz] bandwidth when vehicles are almost never operated in and around intersection. Also, the frequency bandwidth of vehicle crash sound is showed sound pressure difference oyer 30[dB] higher than when there is no occurrence of traffic accident below 500[Hz].

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.763-766
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• 2004

Recently, various acoustic artifacts that contains speaker have been produced such as cellular phone. Speaker consists of diaphragm generating sound and coil vibrating diaphragm. Generally, good speaker means that it has a wide frequency range, high output power rate to input power and flat sound pressure level in specified frequency range. Acoustic characteristic was estimated through the experiment and computer simulation, or sound power was controlled with acoustic sensitivity in a natural frequency range fer last decade. However, the flatness of sound pressure level has not been considered to enhance the sound quality of a speaker. Tn this study, a method for speaker design is proposed for a good acoustic characteristic, which is flatness of SPL(sound pressure level) and wideness between the first and second natural frequency. SYSNOISE is used fer acoustic analysis and ANSYS is used for harmonic response analysis and modal analysis. Optimization for acoustic characteristics of a speaker diaphragm is performed using ModelCenter. All analyses are done within a frequency domain. And we confirm that the experimental and computational simulations have similar trend.

• Polymer(Korea)
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• v.25 no.3
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• pp.427-434
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• 2001

The sound absorption materials With polyester (PET) were prepared for automobile. They consist of 3 layers with different size of PET fiber (3 and 15 deniers) in order to optimize the characteristic of sound absorption, and with various densities (895~1790 g/$cm^2$) by controlling the weight of PET of each layer. They were also compared with the commercial sound absorption materials made of glass wool. It was shown that the new PET had better absorption capability in both high and low frequency regions than that of the commercial material. It was revealed also that the density and the thickness of PET played an important role to determine the capability of sound absorption. The NRC (noise reduction coefficient) was increased by 22-39% with optimized PET sound absorption material. It should be noted that the PET can substitute the glass wool, a commercial sound absorption material, in view of environment and as well as recycle capability of sound absorption.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.88-94
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• 2022

The relationship between sound and vision was experimentally confirmed by physicist Ernst Florens Friedrich Chladni as early as the 18th century and formally entered into systematic research. With the development of emerging media technology, sound reactive type visual content is not limited to a single visual interaction based on the vibration of sound, and its visual content shows a diversified and scalable development trend according to different purposes in many fields. This study analyzes the development and changes of sound visual art contents from early stage to modernization, and analyzes the development characteristic of sound visual art content in different fields and scene environments influence by interactive media, new media technologies and devices by means of case analysis. Through this research, it is expected that the sound reactive type visual art content can continue to develop and extend in the existing fields, while explore the scalability of the application of sound reactive type visual art content in more fields.