• Journal of the Ergonomics Society of Korea
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• v.1 no.2
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• pp.33-37
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• 1982

인간의 가청 영역은 어린이의 경우에 20 Hz-20KHz로 알려져 있다. 그러나, 20Hz 이하의 초저주파 영역에서도 그 음압 레벨이 높은 경우에는 인간이 감지할 수 있다는 사실이 알려졌는데, 그것은 듣느다기 보다는 느낀다는 것으로 표현되고 있다. 초저주파 음이 인간에게 미친다고 생각되는 좋지않은 영향 때문에, 60년대말 이후에 새로운 종류의 연구 과제로서, 음향학자, 심리학자, 의학자 등에 의해 활발히 연구되고 있다. 게다가 경제의 고도성장 및 환경 개선의 노력에 따라, 대기 오염, 가청 소음, 진동 등의 전형적인 환경 공해 외의 초저주파음 공해에 대한 사람들의 인식과 불평이 문제시 되고 있다. 즉, 고주파수의 음이 잘 소음된 곳에서, 소리가 잘 들리지는 않으나 항상 사람들을 불안하게 하는 그 무엇이 있다는 것이다. 이에따라 지난 몇 년간 인간의 산업 활동과 관계 있는 높은 레벨의 초조주파 소음의 발생원이 확인되었고, 그에 따른 대책 및 설계 단계에서의 고려가 요구되고 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.175-183
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• 2021

This paper studies measurement of sonic boom created by supersonic flight and its arrival angle estimation techniques. Since sonic boom propagates as an impulsive noise and includes infrasound frequency, we propose measurement instrumentation acquiring sonic boom signature without distortion. And we suggest the methodology for an arrival angle estimation with its performance analysis in accordance with sensor array configurations. The performance of our estimator is verified by comparing theoretical performance bound with statistics of its Monte-Carlo simulation results. Furthermore, we presents the analysis of the sonic boom measurement from real flight tests. This work provides an intuitive concept for sensor array configurations and measurement instrumentation.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.322-330
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• 2020

This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.52-57
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• 1999

Korea Earthquake Monitoring System(KEMS) in the Korea Institute of Geology Mining and Materials(KIGAM) as detected more than 1000 events since the end of 1998. But not all events are interpreted as earthquakes because many events are concentrated on daytime. It strongly implies that in addition to earthquake these events include artificial effects such as industrial blasting. Before the determination of eathquake charactertistics in the korean peninsula it is necessary to discriminate the detected events as earthquakes or artificial events. For the discriminant study KIGAM and SMU(Southern Methodist University) installed a triangular four-element 1-km aperture seismo-acoustic array at Chul-Won area northeast of Seoul Korea. Each array element includes a GS-13 seismometer in the bottom of borehole and a Validyne DP250-14 microbarometer sensor mounted inside of the borehole 1,2 meter deep connected to a 11 arm radial array of 10m porous soaker hoses. This array introduce the use of 2.4-GHz radios for inter-array self-contained solar-charged power system and GPS time-keeping system. A 24-bit digital data acquisition system performs 40 SPS in the infrasound and seismometer data. Velocity and direction of wind and temperature are also measured at hub site and included to the data stresam. This seismo-acoustic array will be used to identify and locate associated with industrial blasting and these identified and located events will be applied to form a ground truth database useful to assist the other development of discriminant studies.

• Journal of Korea Entertainment Industry Association
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• v.10 no.4
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• pp.303-310
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• 2016

Due to population explosion and develop of the industry, expressways, national roads and railways has been developed a lot. But it increased the disconnection of the ecosystem. The phenomenon of wild animals' habitat simplification has been increased. The damage appeared in succession because of the harmful wild animal. Our country is making efforts relief of some affected farming household's financial compensation. But the affected populations can't sleep at night or they are suffering in their basic life because of this kind of night patrol. This research is based on the study of wild animal's ecosystem and their habits, generate and regenerate supersonic waves and infrasound, prevent wild animal's approach to some extent and stop the approximation effectively, focusing on develop a quadcopter about discrete pulses system.