• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.312-318
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• 2022

This paper proposes a model which classifies the type of guns and information about sound source location using deep neural network. The proposed classification model is composed of convolutional neural networks (CNN) and long short-term memory (LSTM). For training and test the model, we use the Gunshot Audio Forensic Dataset generated by the project supported by the National Institute of Justice (NIJ). The acoustic signals are transformed to Mel-Spectrogram and they are provided as learning and test data for the proposed model. The model is compared with the control model consisting of convolutional neural networks only. The proposed model shows high accuracy more than 90 %.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1123-1128
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• 2004

An experimental study on firing noise of K2 rifle was performed. Firing noises of K2 rifle were measured at close distance to rifle. Firing noise of K2 rifle which made in Korea, has not measured before. The measurement of firing noise at close distance is not simple, because the amplitude of firing noise is much bigger than the measuring limit of ordinary sound level meter even though it uses a signal attenuator. The measurement of firing noise at close distance is necessary for noise source positioning and for obtaining the sound power of K2 rifle. By this experimental study, the firing noise levels of K2 rifle at different positions are obtained and these data can be used to Predict the sound pressure level at any distance from muzzle of the rifle. Also these data can be used to calculate the threshold shift of gunner's ear.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.596-597
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• 2013

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.486-492
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• 2010

This paper studies an experimental analysis of the impulse noise of K2 rifle when its bullet passes through the large tube(length 1.84m, outer diameter 50cm, glass wool & steel). In experiment, the characteristics of the sound of shooting were different according to the way of shooting; the results of the experiment are given below. First of all, the shooting sound was lower in single-shot shooting, when compared to 3rds burst-shot shooting, difference averaging 2.8dB, 4.0dB at maximum. In short, the difference is minuscule. Secondly, the sound of the K2 rifle was diminished when shot in a tube, ranging from 2.7dB to 15.4dB, averaging 8.2dB. Thirdly, the shooting sound of the K2 rifle was diminished as the insertion depth deepened with formulas given in Fig. 5, 6. Fourthly, basic data for excluding sound of the shooting were presented. Lastly, the characteristics of the shooting sound could be equally used as a basic material for developing marksmanship and sharp-shooting detection device.

• Journal of the Korea Society for Simulation
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• v.30 no.3
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• pp.31-39
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• 2021

During artillery fire, an excessive level of impulse noise propagating in the form of a storm wave is generated. Since the sound of impact from the fire affects the stability of the surrounding structures, the artillery and the structures must be separated from each other by the proper distance to avoid damages from friendly fire. However, if they have already been built within the distance, it is possible to prevent the damages by building sound barriers between them. In this study, the proper separation distance between the artillery and the structure was calculated, and the insertion losses due to various heights and shapes of the sound barrier were simulated by using the BEM(Boundary Element Method), and conclusively the optimal sound barrier was selected.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.321-322
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• 2012

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.36-43
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• 2004

In 1909 Hiram P. Maxim invented one of the first metal silencers for reducing sound levels in firearms. Silenced me have been mainly applied in the hunting and military operation. In particular special force make use of silenced rifle because it is low sound level. This paper considers experimental analysis for the characteristics of shock wave caused by shooting of a silenced me. Experimental results Indicate that the sound level of K-7 silenced rifle was lower than the sound level of MP5 silenced rifle. And, Sound Power Level of K-7 silenced rifle at a distance more than 75m or loom have nearly the constant value. This results that suggested the characteristics data about K-7 rifle's impulse noise will be apply to design the silencer of a small arms.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.578-583
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• 2016

In order to provide a basis data for design of small arms and their silencer, an experimental study on firing noise of small arms was performed around the muzzle of a gun. For this experimental comparison analysis, the target small arms were included most operating small arms in our country. The sound pressure levels were measured at a certain distance which was predetermined according to US army firing test procedure, TOP 3-2-045. By this experimental study, the sound pressure levels of 5.56 mm caliber small arms are 143 dB ~ 145.4 dB and 7.62 mm caliber small arms are 144 dB ~ 145.2 dB. Between the heavy machine gun K12 and M60, the sound pressure level of K12 is slightly lower than M60.Also silencer for K14 snifer rifle was tested. Using this result, it has been found that the reduction effect of the silencer is 15.4 dB but the improvements of silencer performance in the high frequency range have to be studied later on.

• 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 Korean Society of Transportation
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• v.28 no.3
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• pp.51-57
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• 2010

In this study, damages due to the aircraft noise were examined in more than 190 elementary, middle and high schools near the airports in Korea, and the persecutory idea forecast model was established using the quantification theory type II. Via the survey of 1,012 teachers in the schools, a class interference forecast model was established, and the noise characteristics of five areas, four military/civil common-use airports and one shooting range, were examined. The following conclusions were made from the study. WECPNL values in the five military/civil common-use airports showed that all of them were Class 1 or 2 affected areas, which indicated that they had serious aircraft noise problems to be addressed. The most influential factor in the aircraft noise persecutory idea model was the distance between the airport and the school. It showed a positive relationship at a distance of less than 5 km, and a negative relationship at a distance of 10 km or more. The number and time of aircraft noise exposure as well as the types of airports and window structures had strong influences. The forecast model had a correlation ratio of 0.56, which indicates that it is highly appropriate. In the class interference factor analysis, the time and number of aircraft noise exposure were strong influential factors, and the results varied according to the service duration and sex of teachers. This model had a correlation ratio of 0.61, which indicates it is highly appropriate.