• Journal of Preventive Medicine and Public Health
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• v.30 no.2 s.57
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• pp.356-368
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• 1997

In effort to determine whether aircraft noise can have health effects such as hearing loss, hypertension and psychological stress, a total of 111 male professors and administrative officers working a college near a military airport in Korea(exposed group) and a total of 168 males and 112 females matched by age groups(control groups) were analyzed. Personal noise exposure and indoor and outdoor sound level of jet aircraft noise were measured at the exposed are3. And pure tone, air conduction test and measurement of blood pressure were given to the exposed(males) and matched control groups (males and females). BEPSI(Brief Encounter Psychological Instrument) and psychological response to aircraft noise were examined for the exposed group. The noise dosimetry results revealed time-weighted averages(TWAs) that ranged from 61 to 68 dBA. However the levels encountered during taking off jet airplanes reached 126 dBA for two half minutes time period. Th, audiometric, test showed that mean values of HTL(hearing threshold level) in exposed group at every frequency(500, 1,000, 2,000, 4,000, and 8,000 Hz were much lower than them of male and female control groups. And in old age groups, interaction of age and noise was observed at 8,000 Hz in both ears(p<0.05). Conclusively, aircraft noise does not appear to induce hearing loss directly in high frequency, but may decreased hearing threshold level by interaction of aging process and noise exposure. However, difference of mean values of exposed and control groups on blood pressure was not significantly. In psychological test, annoyance was the most severe psychological response to noise in exposed group, but mean value of BEPSI was not correlated with job duration in exposed group.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.6
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• pp.437-444
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• 2002

This paper is to provide the basic way of a acoustical evaluation and efficient control noise by investigating the limits of perceptual loudness of living environment and by finding out any correlation between Physical characteristics of noise and psychoacoustic parameters. The limits of perceptual loudness were selected by the subjects in a chamber for residential and working environment. And the noise sources were analyzed to find out whether there is any correlation with Zwicker parameters and ACF factors. In this study especially, to set up the domestic evaluation grade about floor impact noise. we'd like to suggest the loudness Perception research result as fundamental resource for setting up the evaluation grade through the result that is based on annoyance. In the result of this research, upper limit of heavy-weight impact noise was L-60, and lower limit of it was L-50. On the other hand, upper limit of light-weight impact noise was L-70, and lower limit of it was L-55. It seemed that the loudness of noise from vacuum cleaner noise does not affect its perceived noisiness. Noises implicated In human such as floor walking noise and talking sound, are the most irritating noise in office environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.148-152
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• 2007

In recent days, on account of the cultural development and the improvement of citizen's consciousness level, it is the real situation that the construction of small-scaled Multi-Purpose Hall where various cultural events could be performed, is on increasing. However, since the most of Multi-Purpose Hall had been designed and built up without any consideration on Acoustic Factor, many problems are on occurring thereat. Since those small-scaled Multi-Purpose Hall have been mostly used with the finishing material which contains a high degree of Acoustic Absorption indiscreetly, both diffusion and reflection of sound are not establishing properly, and because thereverberation of sound is very low, in case of musical performance by musical instrument, its sound hears too arid and stiff, there occurs some acoustic defect such as it becomes difficult for music appreciation with sufficient timbre, so that the capability improvement on the matter is urgently requiring situation. Therefore, this Study has tried to seize the satisfaction level about the small-scaled Multi-Purpose Hall after betterment of the acoustic performance by appraise the acoustic condition of the Hall, using Auralization Technique that can experience Virtual Acoustic Field regarding to the small-scaled Multi-Purpose Hall as its object. It is deemed that such research result could be practically used as the useful material which enables to bring a reduction effect of construction cost as well asenhancement of the acoustic performance through its presupposition?control on the acoustic problem when construction or renovation of other similar small-scaled Multi-Purpose Hall in the future.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1096-1102
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• 2013

The useful practical land shall be reserved when an artificial land covers the railway and road. However, the problem is that since the artificial land places directly on the top of noise sources likely on the railway and road there will arise the weak points, noise and vibration. On this study based on creating the artificial land on the top of a railway vehicle base and placing a tenement on that land, it was comprehended the noise influence from the railway car through the simulation. In order to secure the input value for the simulation, at first measured the noise condition of the railway station building and the railway vehicle base. The output value for the railway station building (place A) was around (53.6~57.6) dB(A), the equivalent continuous sound level for an hour, and for the railway station building (place B) it was around (63.7~68.9) dB. The maximum outdoor noise of the tenement on the artificial land was measured as 64.1 dB(A) under the fixed condition on the simulation modeling. The built purpose of placing the artificial land to prevent the noise influence from the railway met the expectation to be less influenced on the tenement. Rather, because of placing the artificial land the noise level on the lower space could be increased so there requires having a noise control.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.214-220
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• 2019

Hearing impaired people are apt to be in danger because they can't detect danger with sound. Hearing impaired people have less risk-detection ability than non-disabled people because of lack of hearing. There are many devices to help the hearing impaired, such as hearing aids. A hearing aids can be helpful, but it may not be available depending on the degree or type of hearing loss for example, to the hearing-impaired people with little remaining hearing of high frequencies, ordinary hearing aids are not very useful for understanding the high frequency consonants and it requires a high cost, from thousands to tens of thousands of dollars. Also, it is difficult for the underprivileged, such as the low-income bracket and the elderly, to use them because they are difficult to manage. Therefore, this paper describes the development of low-cost wearable device to assistant a hearing-impaired people using Arduino. Also, it accepts values from switches or sensors and can control external electronic devices such as LEDs and motors to create objects that can interact with the environment. In this is paper, through sound sensors, the ambient sound was taken as an analogue value and transmitted to the aduino board, and the vibration motor was operated when the noise was generated, so that the user could be aware of the occurrence of danger.

• Explosives and Blasting
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• v.31 no.1
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• pp.11-22
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• 2013

This study compared and analysed ground vibration, size of underwater background noise in fish farms and underwater object noise of blasting and obtained ground vibration prediction equation through a regression analysis and correlation equation between underwater object noises in order to predict degrees of underwater noise in blasting and organize underwater noise control regulations. Before the study, when background noise of fish and shellfish farms with different conditions was measured, levels of background noise were different according to environmental characteristics of each farm. Ground vibration which causes underwater noise was measured to obtain a correlation equation between ground vibration and underwater object noise. Therefore, if underwater noise is predicted for each construction with a use of a correlation and permissible standards appropriate for each condition are applied for design and construction, financial loss from damages to fish and shellfish caused by development of insufficient technological and engineering logic can be prevented and successful construction with safety of underwater creatures guaranteed can be achieved.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.983-989
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• 2014

In this paper, a new active noise control method was proposed to decrease a weight of car, and to increase a fuel efficiency and to provide passengers' comfort and calmness, instead of a passive noise control method such as sound absorbing and insulating materials. The proposed method is an enhanced active noise controller operating by a bidirectional control algorithm. The algorithm is simple to implement and available to analyze mathematically with nearly equivalent complexity of computation. Through simulations for engine noises of a car, the proposed controller was verified that its performances of time and frequency domain were superior to those of both feedforward and feedback controllers, and it had better capability of controlling the noises when the impulsive disturbance was flow in and the response of secondary path was varied.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.60-65
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• 2015

In this paper, we used the sound of gunshots recorded by multiple microphones to increase the accuracy of the calculation of the distance between sniper and the microphone array. This method is crucial for achieving military objectives. Gunshots are comprised of the explosion of driving gas from the muzzle and the supersonic shock wave from the flying bullet. The original distance calculation method compares the time difference of arrival and angle of incidence to estimate the sniper's location. The disadvantage of this method is that when the angles of incidence coincide the margin of error increases, to solve this problem we suggest a new method using the characteristic changes of the shock wave with the increase of perpendicular distance between the microphone and the trajectory of the bullet. This theory is verified by experiments.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.9-13
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• 2009

A cause of noise and vibration which come from a Combustion of gas heater are a combustion roar and Combustion oscillation. A character of a combustion roar is that sound pressure is distribute with broad band frequency. otherwise, The presence of combustion oscillation caused by positive Feed Back in Combustion Chamber break out a noise and vibration. Accordingly, The method that be solved a noise and vibration is to make each natural frequency different frequency. first, in order to solve problem, we control ratio of fuel and air. that is, Keep away resonance. second, in order to changing natural frequency of Combustion Chamber, We changed the shape of Economizer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.111-118
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• 2006

Relatively high noise emitted from Transformers of in-door-substation in urban area has become the target of public complaints and the frequency is on the rise in these days due to an extension of transformer installations and new establishment of substations. The noise consist of harmonics of a specific frequency of the twice of the electricity frequency(60[Hz]), which is hard to control by using the general sound proofing techniques. In this work, several effective methods were discussed for reducing the noise from a transformer, which is transmitted through explosion preventing shutter and air tunnels. By applying to the actual site, the effects of the methods were verified.