• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.49-57
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• 1998

The acoustic signatures from a propeller fan under non-uniform inlet flow conditions were measured to reveal the mechanism for tonal radiation. Experimental studies were carried out by generating non-uniform turbulent flows with circumferential and radial components of harmonic incoming gust deliberately. This paper reports the measured acoustic power exponents and cross-spectra for circumferential and radial disturbances at a specified flow-rate coefficient.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1756-1757
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• 2011

본 논문에서는 FXLMS 알고리즘을 이용하여 3차원 폐공간(반무향실)에서의 순음(125Hz)을 이용하여 부 음원과 에러센서의 위치 변화에 따른 소음저감 정도를 분석하였으며, 이 결과를 바탕으로 능동형 방음벽의 구현의 기초자료로 활용하고자 하였다. 부음원(제어스피커, 이하 부음원)과 에러센서간 거리차는 0.5m, 1.5m, 2.5m를 대상으로 실험을 실시하였으며 그 중 거리차가 1.5m 지점의 경우, 125Hz부근에서는 최대 18.3dB, Overall(80Hz~200Hz)값은 18.2dB(A)의 소음저감 효과가 있는 것으로 나타나, 가장 효과적인 부음원과 에러센서간의 거리차인 것으로 평가되었다.

• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.353-357
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• 2005

Declining auditory performance with advanced age is a well known and common problem that is becoming more Prevalent due to the increasing number of elderly people in our society. We introduce a novel ARCISM (Audiogram Result Computer Input. Save & Management software) data management program which enables the assessment of the risk of past history of hearing impairment on the basis of known risk factors. This study investigates the reference levels of pure tone hearing threshold of normal aging in Korean and the difference between fenders. The subjects were carefully selected by questionnaire and absence of any history of otologic infection, noise exposure. and ototoxic drug among 1603 subjects. who visited Health Promotion Center in Daegu Fatima Hospital for one year. The results show (1) hearing sensitivity declines with age. (2) higher frequency shows steeper slope of hearing declines than lower frequency. and (3) there were more hearing loss at 4 and 8 kHz in men than in women. Due to the ARCISM program. it was possible to manage huge data of hearing results and to obtain the reference level of a9e-related hearing declines. Furthermore, we expect that the results of this study can be the fundamental data for hearing rehabilitation for the elderly and for developing suitable hearing aids for Korean.