• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.463-468
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• 2011

According to a quantum leap of the performances of automobile, environmental factors are important as functional factors, especially noise. BLDC motor, one of the part of automobile, is also no exception. In this paper, investigation of the sound sources of outer rotor type BLDC motor is performed. In order to reduce noise, it must be necessary knowing sound source. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. For structural analysis, modal experiment and 3D mode analysis are performed. On behalf of electromagnetic analysis, 2D finite element method is carried out. Finally, coupling analysis is performed in order to know about influence between two factors.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.367-371
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• 2014

Based on ISO 7235, an experimental setup to measure the acoustic performance of splitter type dissipative silencers are fabricated. The length of each duct, sound source, microphone locations, modal filter, and anechoic termination are considered in the design of this setup. The modal filter is a particularly important factor because it affects the limit of measurement, which is also determined by the amount of flanking transmission of sound generated by the sound source to microphones. The effects of absorptive materials, media which covers the materials, and the number of splitters on the noise reduction of the sample silencers are experimentally investigated. The insertions loss of silencers with media and higher number of splitters increases, especially at higher frequencies.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.955-956
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• 2014

Active noise control is noise reduction method by generate anti-phase control signal for destructive interference of through control speaker. purpose of this paper is create a virtual control source at a using the DBAP(Distance Based Amplitude Panning) algorithm which is one of the three-dimensional sound reproduction method, and verified through the experimentally for noise control method through the virtual control source. We compared active noise method by using one control speaker with active noise control method by using DBAP algorithm.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.89-93
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• 2004

To numerically construct the sound fields by a plenum fan mostly found in Air-Handling Unit (AHU), the Kirchhoff-BEM approach was applied to the near-field data of a turbo fan. The scattering effects were found to be significant by the plenum box structure for high-frequency components of source. The directivity petterns and sound pressure levels were also dependent upon the helmholts number which must be considered of the design stage for sound reduction program.

• 음성과학
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• 제11권4호
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• pp.29-42
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• 2004

This paper presents an implementation of real-time speaker localization using audio-visual information. Four channels of microphone signals are processed to detect vertical as well as horizontal speaker positions. At first short-time average magnitude difference function(AMDF) signals are used to determine whether the microphone signals are human voices or not. And then the orientation and distance information of the sound sources can be obtained through interaural time difference. Finally visual information by a camera helps get finer tuning of the angles to speaker. Experimental results of the real-time localization system show that the performance improves to 99.6% compared to the rate of 88.8% when only the audio information is used.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.329-336
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• 1998

The characteristics of vibration and sound signals which occurs at the driving system of electric train are investigated in this study since the vibration of driving system is one of the main sources of vibration and sound in electric train. The vibration signals are changed its signal patterns during the transmission from the source to passengers due to noise or several unknown factors. To avoid the complexity of actual signals of electric train, signals from experimental apparatus of motor/gear driving system are analyzed to find the appropriate method of analysis and to characterize the signal patterns. The used methods are waterfall diagram, transfer function and modal analysis. The results shows that the vibration signals are usually originated from motor bearing and gear meshing and these signals are transmitted to bottom or bogie. Also, the sound signal is similar to the vibration of bottom or bogie, but it is not so clear to figure out the source of vibration.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1441-1447
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• 2008

This research studies the effects of community noise around railway, noise from the inside/outside noise of the High-Speed EMU. First study part of this year is research of the noise source. The modeling methodology for prediction of noise level including the frequency property, velocity dependence, sound pressure of noise source is investigate. Second part is research on the sound transmission loss. An exclusive program which could analyze the sound transmission loss of the floor, the sides(mirror), insulator in High-Speed EMU has to be developed. Third part is research on the train inside/outside and Prediction for community Noise. In order to predict the noise when the High-Speed EMU is traveling at the outside and along tunnels, the result of the research can be derived by evaluating the effect of the noise on the upper/middle parts of the carriage and on the railroad way round about with using the program.

• 수산해양기술연구
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• 제21권1호
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• pp.12-18
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• 1985

고압변압기의 1차측을 제어하고 2차측에 유도된 전압을 이용한 수중방전음원의 전기음향학적 제특성을 분석.검사한 결과는 다음과 같다. 1. 방전시 2차측 전류는 초기에는 Ohm 법칙을 따르다가 전류가 최고 6.3A 흘러 절연 파괴되었으며, 그 순간 방전음이 생성되었다. 2. 전류인가점과 방전음 생성문의 시간차는 약 3ms였으며, 전압이 최고일 때 절연파괴가 일어나 방전음이 생성되었다. 3. 전극의 끝이 뾰족할수록 2차측 전압이 높을수록 음압수준은 높았다. 4. 뾰족한 형태의 전극은 전극간격이 100cm일 때도 방전이 일어났으며 전극간격이 1cm이상부터 비교적 안정된 방전음이 생성되었다. 5. 방전음의 펄스폭은 약 0.15ms인 Shock Wave였으며, 10HKz 이하의 합성저주파 성분이었다.

• KIEAE Journal
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• 제12권4호
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• pp.83-88
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• 2012

As for the generally preferred sound sources used in the test, the sound of water and the birds chirping were highly valued. And they have found that preference of the subject is increased if background music which mixed well with the sound sources were provided together. On the other hand, the sound sources of low satisfaction were judged at be church bells, bell of Emile, and fulling cloth, which not mix well with interior landscaping. If the physical elements of interior landscaping were equally composed, it has found that the larger were a of water space is, the higher satisfaction more than other sound sources. Average satisfaction of background sound in interior landscaping classified according to the characteristics of space has found that satisfaction of the birds chirping and music in working space and satisfaction of water sound and music in commercial space were high. Women judged that satisfaction of the birds chirping and music in working space and satisfaction of water sound and music in commercial space whose values were the same with the average ones were high, while men judged that satisfaction of the song of birds and music in working and commercial space is high.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.752-760
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• 1993

We research ed on the noise control of a head feeding type combine harvester. It is a kind of combine harvester developed in Japan. And at present, it is used by most Japanese farmer. For a head-feeding type combine harvester it is very difficult to determine the sources of noise because it is a combination of reapers and automatic , threshers and several running parts. However we succeeded in finding out the sound sources of combine harvesters and analyzing their sound by the using sound intensity method. The sound intensity Method is a very up-to-date method to measure and analyze Sound Intensity Levels and sound directions at several measuring point sin a specified area. In this research, first a conventional sound level measurement method is used and secondly the sound intensity method. The first method shows a rather great limitation in allowed exposure duration. The second method shows pin-points the engine itself as being the main source of noise, causing sound flows a ross the operator's seat.