• 한국소음진동공학회논문집
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• 제17권8호
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• pp.736-740
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• 2007

A laboratory study on low frequency noise assessment has been carried out to evaluate the relevance of the weighting curve. Especially, the A-weighting curve which is used in most noise assessments has been evaluated using the acceptability limit in this study. The acceptability limit is one of the indicators in which the subjective responses were well-reflected. For the measurement of the acceptability limit, pure tone stimuli were used in the frequency range between 20 and 200 Hz. The measurement was proceeded in the anechoic chamber to minimize the background noise level. A total of 29 test subjects, who were aged between 19 to 33 years, participated in this study. They had been exposed to various stimuli for about 1 hour by supra-aural earphone. The measurement consisted of two listening sessions: hearing threshold and the acceptability limit session. The results showed that the tendency of the acceptability limit curve was approximately equal to C-weighting curve which had been found to be superior to A-weighting curve in assessment of low frequencies.

• 한국추진공학회지
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• 제10권3호
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• pp.32-40
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• 2006

본 연구는 소형 로켓모터의 지상연소시험 시 동적 방사선투과검사를 이용하여 로켓모터의 내부 연소현상을 실시간으로 관측하는 시험 기술을 개발하고자 하였다. 이를 위해 자체 설계/제작한 영상촬영상자와 300 kV급 X선 발생장치를 사용하여 지상연소시험을 실시하였고, 연소 중 발생되는 진동과 소음 등의 외부 환경인자로부터 영상의 안정화와 장비보호를 위하여 방진/방음 장치를 개발하여 적용하였다. 시험결과, 측정부위의 진동크기가 장비의 정상운용을 위한 허용한계 이하로 측정되었으며, 연소 중 로켓모터 내부형상과 추진제 연소면의 변화를 명확히 관찰할 수 있었다.