• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.3
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• pp.184-193
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• 2001

The present study develops programs simulating the internal pressure change of cars due to the change of external pressure when trains run into or passing each other in a tunnel. A new continuous ventilating system control method has been developed in order to alleviate the aural discomfort of passengers riding a high speed train. This method is based on the change of the charged and discharged flow rate by detecting the air pressures generated outside and inside of the train. When the outside and inside pressure are detected, the speed of the charge or exhaust fans and also the valve opening ratios are changed. The elementary performance of the system is checked using dta of the TGV-K high speed train at a speed of 300km/h. Moreover, applicability of the system to the Koran high speed train at a speed of 350 km/h is ascertained by simulation and its effectiveness as a means to alleviate the ear pains is confirmed. This application of the system to the Korean high speed vehicles running in the speed range of 350km/h is considered to have good prospect.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.56-63
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• 2013

This study surveyed MP3 player usage and evaluated its effect on hearing thresholds in high school students. It is reported an increase in risk factors for hearing loss in adolescents that paralleled the increase in sales of MP3 players. A total of 538 students in two high schools in Gwangju province participated in this study. The students completed questionnaires about their MP3 player use and their pure tone hearing thresholds were tested at several frequencies. The questionnaire results indicated that 61.1%, of the students listened to music on MP3 players for more than one hour per day, 71.6% listened for four or more days per week, and 36.7% had listened for more than 3 years. Listening at a high volume of 60% of the maximum level was reported by 51% and they recognized having ear pains. The pure tone hearing threshold was found to be raised for the adolescents who had a long history of MP3 listening at high volume (p< 0.0001).