• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.69-75
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• 2010

In this paper, we analyze an effect co-existence between digital television (DTV) and 802.22 wireless regional area network (WRAN) systems. We set DTV as an interfering system and 802.22 WRAN as a victim system. When they share the same spectrum, we calculate the minimum separation distance. In analysis, we compare a minimum coupling loss (MCL) with a transmission loss (TL) for determining whether there exists the potential interference or not. The minimum separation distance is determined when the TL is larger than the MCL. In this case, the DTV system does not affect any harmful effect to 802.22 WRAN.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.478-489
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• 2020

This study presents an analysis of infrasonic signals from two accidental explosions in Gwangyang city, Jeonnam Province, Korea, on December 24, 2019, recorded at 12 infrasound stations located 151-435 km away. Infrasound propagation refracted at an altitude of ~40 km owing to higher stratospheric wind in the NNW direction, resulting in favorable detection at stations in that direction. However, tropospheric phases were observed at stations located in the NE and E directions from the explosion site because of the strong west wind jet formed at ~10 km. The transmission losses on the propagation path were calculated using the effective sound velocity structure and parabolic equation modeling. Based on the losses, the observed signal amplitudes were corrected, and overpressures were estimated at the reference distance. From the overpressures, the source energy was evaluated through the overpressure-explosive charge relationship. The two explosions were found to have energies equivalent to 14 and 65 kg TNT, respectively. At the first explosion, a flying fragment forced by an explosive shock wave was observed in the air. The energy causing the flying fragment was estimated to be equivalent to 49 kg or less of TNT, obtained from the relationship between the fragment motion and overpressure. Our infrasound propagation modeling is available to constrain the source energy for remote explosions. To enhance the confidence in energy estimations, further studies are required to reflect the uncertainty of the atmospheric structure models on the estimations and to verify the relationships by various ground truth explosions.