• Earthquakes and Structures
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• v.17 no.6
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• pp.591-598
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• 2019

The most recent shaking experiences have demonstrated that the predictions of the seismic models are not always in agreement with the registered responses, especially in the face of extreme earthquakes. Records collected from 1960 to 2011 at a rock-like site are used to develop a neural network that permits to estimate peak ground accelerations via the magnitude, the focal depth, the site-source distance and a seismogenic zone. The neural model is applied to the 8th and 19th September 2017 events that hit Mexican territory and the obtained results show that the network is flexible enough to work appropriately to various conditions of intensity and sites-sources with remarkably predictive capacity. The neural-attenuation curves are compared with those obtained from Ground Motion Prediction Equations and their performance is assessed for events, in addition to the devastating Mexican events, from Japan, Taiwan, Chile and USA.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1002-1003
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• 2006

Power line communication: PLC which easy to install at anywhere near outlet for electric machine. PLC uses transmission line for voltage of which is 60 Hz. One of the important thing is the processes of adding signal to power line and extracting the signal from power line, another is to choose the strong modulation method which sends signals to long distance without loosing in PLC channel. but PLC channel have very high and variable noise and attenuation and then it is very hard to transmit optimally between the transmitter and the receiver. AWGN, impulse noise and attenuation are created. To overcome the noise and attenuation. Multi-carrier Modulation methods like as OFDM and DMT which divide the channel into many sub-channel are powerful communication methods for PLC. In this paper, PLC channels are simulated for getting BER by Matlab simulink

• The Journal of Engineering Geology
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• v.6 no.3
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• pp.131-136
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• 1996

Attenuation characteristics of AF/MA motions which involve high frequencies were investigated through pencil-lead fracture tests on a fine-grained granite specimen. For the study, calibrated six transducers were employed to detect the signals and the pencil-lead was fractured as a step unloading force to generate AE/MA signals. The arnplitude AE/MA waves is affected by the relative orientation of source and transducer as well as the source distance. The attenuation constant for Charcoal granite is obtained as 1.058 which could be applied for a given ray-path regardless of the relative orientation of source and transducer.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.33-36
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• 2008

In Korean Building Code 2005(KBC-2005), the Seismic Zone Factor is regulated by separating the seismic zone into two part. This seismic zone factor is not matched to regional seismic characteristics of our country because the factor is based on International Building Code 2000 (IBC-2000) of USA. This study inquiry for having a sufficient grasp of the seismic characteristics of south Korea region and appling for the seismic cope plan. We have collected and analyzed earthquake record happened in domestic region. There are two kinds of earthquake record. One is Historical earthquake data, another is Instrumental earthquake data. I used Instrumental earthquake record data which reliance is higher than historical earthquake data for proposing attenuation formulas by analyzing a correlation the epicenter and the distance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.39-55
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• 2022

This study carried out the laboratory tests for AE signal attenuation to determine the attenuation coefficient (α) of silo concrete in Gyeongju low and intermediate-level disposal environments. The concrete samples were prepared by satisfying the concrete mixing ratio used in the Gyeongju disposal silo, and these samples were additionally exposed depending on the temperature conditions and saturation and, dry condition. As a result of attenuation tests according to the transmission distance on three concrete specimens for each disposal condition, the AE amplitude and absolute energy measured on the saturated concrete were higher than that of the dry concrete in the initial range of the signal transmission distance, but the α of the saturated concrete was higher than that of the dry concrete. Regardless of the saturation and dry conditions, the α tended to decrease as the temperature increases. The α had a more major influence on the saturation and dry condition than the temperature condition, which means that the saturation and dry condition is the main consideration in measuring the signal attenuation of a concrete disposal structure. The α of concrete in the disposal environment expect to be used to predict the integrity of silos concrete in Gyeongju low and intermediate-level disposal environments by estimating the actual AE parameter values at the location of cracks and to determine the optimum location of sensors.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.771-778
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• 2007

This study has been conducted to achieve the following objectives: First, in order to understand the horizontal propagation and attenuation characteristics for the railroad traffic noise, we selected areas within 100 meters away from the railroad and then selected Saemaul-ho and Mugoongwha-ho as the subjects for our experiment. In this way, we analyzed the horizontal propagation and attenuation characteristics for the traffic noise occurring in diversified areas. Second, in order to understand the vertical propagation and attenuation characteristics for the railroad traffic noise, we measured and analyzed the distributional characteristics of vertical sound pressure levels on each floor of multi-storied apartment buildings according to changes of traffic load and types, and the existence or nonexistence of soundproof walls. For the case of the railroad traffic noise, we also selected Samaul-ho and Mugoongwha-ho as the subjects for our experiment, and we measured and analyzed the different noise levels on each floor of multi-storied apartment buildings from the soundproof wall. The results of Horizontal propagation and attenuation characteristics for the railroad traffic noise are as follows: In cases of the flat land, cutting land, and bridge area, as distance increases, the sound pressure level steadily decreases. The sound pressure level for the bridge area is higher than that of the flat land with a measurement of $5.5{\sim}10.2\;dB(A)$. Vertical propagation and attenuation characteristics for the railroad traffic noise are as follows: The amount of sound pressure level decrease is $14.2{\sim}14.8\;dB(A)$ for Samaul-ho and $13.5{\sim}14.3\;dB(A)$ for Mugoongwha-ho when measuring the vertical sound pressure levels at heights lower than 4.5 m, which indicates a fairly large decrease. At 6 m, the amount of decrease is 8.6 dB(A) for Samaul-ho and 8.2 dB(A) for Mugoongwha-ho, which indicates a small decrease.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.58-66
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• 2011

This study presents the behavior characteristics of buried three-layered pipeline subjected to pile driving loads. The analysis considered the driving energy caused by 7 tonf of ram weight and 1.2m of stroke. Also the distance from vibration resource to pipeline varies in 5m to 30m. The vibration velocity and stress are investigated at the center of pipeline in longitudinal direction. In the same cover depth, attenuation ratio of vibration velocity and von Mises stresses for distance increment has shown a decreasing trend. The maximum stress occurs at the top and bottom for the inner pipe, however, an irregular stress distribution is found for the outer pipe.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.73-80
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• 2000

The distance correction term -logA0 of the local magnitude scale was estimated for earthquakes in southern Korea using linear least-squares inversion and interpolation scheme. Total 1054 short-period velocity seismograms from 107 local events recorded at hypocentral distances ranging from 10 to 480 km were used in this study. Simulated Wood-Anderson amplitudes were obtained from velocity seismograms with use of revised Wood-Anderson instrument response with static magnification 2080, damping factor 0.7, and natural period 0.8 sec. The estimated distance correction term for southern Korea is found to be -logA0=1.137 log(r/17) + 0.001159(r-17) + 20, where r is hypocentral distance in kilometers. The attenuation rate of this distance correction term falls between those of southern California and eastern North America.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.20-27
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• 2003

The nonparametric method was employed to obtain detailed broadband attenuation characteristics of horizontal Fourier spectra without generally assigned constraint that derived path terms be zeros at a reference distance. Instead, path terms fer a reference distance were obtained based on the physical phenomenon that the seismic phase is stable over the hypocentral distance range from 200km to 400km so that the Q-values evaluated at several distances inside that region should be the same. The inverted path terms show three distinct linear regions roughly divided by hypocentral distances at 65km and 115km. Also complex behavior at the near distance range below 100km was revealed which can not be properly fitted by combination of single $Q_{0}$ $f^{η}$ model and any geometrical spreading models.s.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.699-705
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• 2012

In this paper, an infrastructure-based localization method using underwater wireless sensor network (UWSN) is addressed. A localization using the UWSN is necessary to widen the usage of underwater applications, however it is very difficult to establish the UWSN due to the restrictions of water. In this paper, to extend the usage of UWSN at the infrastructure, we propose a sophisticated UWSN localization method using the Received Signal Strength Indicator (RSSI) of the electromagnetic waves. During the electromagnetic waves propagating in underwater, there arises a lot of attenuation according to the distance, while the attenuation shows uniformity according to the distance. Using this characteristics, the localization system in underwater infrastructure is proposed and the experimental results show the effectiveness.