• Proceedings of the Korea Society of Design Studies Conference
• /
• 2005.05a
• /
• pp.186-187
• /
• 2005

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.5
• /
• pp.2011-2018
• /
• 2011

The paper demonstrates how to deal with the Near-field Acoustic Holography method (NAH) for reducing noise source which is generated in air-conditioning compressor. Sound radiation was measured for both normal compressor and fault compressor. The acoustic noise holograms are predicted by measuring at discrete multiple points around the two compressors and are thereafter reconstructed on the surface of the compressors. 1344 measuring points are used by two microphones in which one is scanning microphone and the other is reference microphone. NAH is a good tool for the visualization of Sound so we can show the source of sound graphically. In this paper, the NAH method found the exact noise source position on the surface of the compressor and the noise-related sub part in the compressor. We found the NAH and is very useful as a noise reduction tool for home-appliance device.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.1
• /
• pp.20-25
• /
• 2008

Acoustic holography exhibits the spatial distribution of sound pressure in time or frequency domain. The obtained picture often contains far more than what we need in practice. For example. when we need to know only the locations and overall propagation pattern of sound sources. a method to show only what we need has to be introduced. One way of obtaining the necessary information is to use envelope in space. The spatial envelope is a spatially slowly-varying amplitude of acoustic waves which contains the information of sources' location. A spatial modulation method has been theoretically developed to get a spatial envelope. By applying the spatial envelope. not only the necessary information is obtained but also computation time is reduced during the process of holography. The spatial envelope is verified as an effective visualization scheme in time domain by being applied to complicated sound fields.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.6 s.111
• /
• pp.565-573
• /
• 2006

Acoustic analysis of a moving sound source required that the measured sound signals be do-Dopplerized and restored as of the original emission signals. The purpose of this research is development of beamforming technique can be applied to the rotor noise source identification. For the do-Dopplerization and reconstruction of emitted sound wave, Forward Propagation Method is applied to the time domain beamforming technique. And validation test were performed using rotating sound source constructed by bended pipe and horn driver. In the validation test using sinusoidal sound wave, sufficient performance of signal processing can be seen, and the effect of measuring duration for accuracy was compared. In the prop-rotor measurements, the acoustic source locations were successfully verified in varying positions for different frequencies and collective pitch angle, in hover condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1104-1108
• /
• 2007

Automobile sunroof buffeting is the tonal noise of low frequency around 20Hz. It occurs due to the acoustic feedback process between the shear layer detached from the leading edge of sunroof opening and the Helmholtz resonator-like property of a car cabin. In this paper, PIV visualization technique is applied to the unsteady flow field around sunroof opening of an SUV in the full-scale automotive wind tunnel in order to find out buffeting mechanism. A phase-marking PIV measurement method, in which image and sound pressure are recorded simultaneously, and a phase-rearrangement post-processing program were developed for capturing noise-related velocity fields without expensive synchronization systems. Through this study, some characteristics of the real-car sunroof shear layers under various deflector conditions were identified and these results can provide insights into the noise reduction mechanism of the tube-type deflector.

• 한국HCI학회:학술대회논문집
• /
• 2008.02a
• /
• pp.184-189
• /
• 2008

In this paper, the sound data either from the sampled or streamed source are utilized for generating a map in the video game play for the dynamiccal use of sound data and synesthesia to users. When users can generate sound in real-time or put the sampled source, it is analyzed and re-processed through Fourier transformation to show the 3D map in dynamic shape over time. We interpolate the generated data to enable the game agents and objects to move.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.8
• /
• pp.774-780
• /
• 2011

Recently, customers have been concerned about vehicle NVH depending on vehicle designing and manufacturing technologies development. In choosing vehicle, vehicle NVH is becoming the most important factor to customers. Especially, a seat is the final stage of vibration transfer path to passengers from all sources of vibration like engine, transmission and etc. And seat is the nearest component from driver's ear. For this reason, seat is the most important component that directly related to ride comfort for passengers. And driver can be influenced sensitively by BSR caused by seat. Thus, evaluating the vibration characteristics of vehicle seat and BSR caused by vehicle seat is necessary to reduce the seat BSR. The rattle noise occurred from seat has evaluated through sound source visualization and multi-dimensional spectral analysis - coherence function technique in this paper. Vibration characteristics of the seat has verified through modal test.

• Archives of design research
• /
• v.16 no.3
• /
• pp.101-110
• /
• 2003

People are surrounded with numerous sounds. The sound is generated from nature and people. For example, the sound enables people or animal responsive to instinctive action. Music or fine arts are presented differently by its distinctive medium. On the other hand, those art forms are similar in a way that people uses right side of brain and intuitions for creative effects. Conjunctions between sounds and visual arts have been progressed to data. From art forms in subjective views to art forms using high technology such as the computer, experiments for sounds visualization are practiced constantly. For that reason, intrinsic attributes of sounds in design area and distinctive qualities are discussed in this study. With respect to existing category of studies and consideration of the tendency in recent researches, the object is to propose direction for the study in regards to methodology of design, which is reconstructing visualized expression.

• 한국가시화정보학회:학술대회논문집
• /
• 2004.12a
• /
• pp.147-155
• /
• 2004

Self-excited noise generation from laminar flames in thin annular jets of methane/air premixture has been investigated experimentally. Various flames were observed in this flow configuration, including conical shape flames, ring shape flames, steady crown shape flames, and oscillating crown shape flames. Self-excited noise with the total sound pressure level of about 70dB was generated from the oscillating crown shape flames for the equivalence ratio larger than 0.95. Sound pressure and $CH^*$ chemiluminescence were measured by using a microphone and a photomultiplier tube. The frequency of generated noise was measured as functions of equivalence ratio and premixture velocity. A frequency doubling phenomena have also been observed. The flame shape during flame oscillation was reconfirmed by a synchronized PIV experiment. The velocity and pressure field were obtained from PIV. The minimum pressure was formed near the edge of flame representing circulation. By comparing the results of sound pressure, flame luminosity and PIV, the noise source can be attributed to the flame front fluctuation near the edge of the oscillating crown-shape flames.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2013.01a
• /
• pp.271-272
• /
• 2013

The music with the times, evolved from analogous tape music to digital music. New authoring tools, interfaces, and applications make us to produce high quality music using cheap equipments. Inspired by this concept, we design an classical chinese style-instrument with the audio-visual interactive function. It enables a user to compose music and to see a vivid picture at the same time.