• Journal of Science Education
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• v.34 no.2
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• pp.432-439
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• 2010

The purpose of this study is to investigate the characteristics of the ionosphere by monitoring VLF radio wave. For this purpose, we set up the SID(Sudden Ionospheric Disturbance) monitoring station in Pohang($36.03^{\circ}N$, $129.35^{\circ}E$), Korea receiving VLF radio wave(22.2kHz) transmitted from Ebino($32.04^{\circ}N$, $130.81^{\circ}E$), Japan. The observed data of radio wave intensities are analyzed to interpret the condition of the ionosphere. We can summarize the results as follows: Radio waves show regular daily variation. We can confirm the daily variation as a result of the formation of D layer. In relation to formation or extinction of D layer, intensity of radio wave gets weak right after sunrise and sunset. Southing altitude also affects the intensity of day time radio wave. At night when D layer disappears, the radio waves shows very irregular changes. The observed radio waves also shows the influence of the seasonal ionospheric variation. Long term observation could provide more detailed interpretation of daily as well as seasonal variation of ionosphere.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.197-202
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• 2016

In this paper, a danger signal to tell caregivers when a dangerous situation occurs, the bio-signal analysis in infants to prevent sudden infant death sudden infant death propose a monitoring system. The Sudden infant death (SID) refers to a healthy baby is unexplained deaths between birth year in the month. Sudden infant death proposed monitoring system is composed of a processor unit and the monitoring and alarm part for processing part and the biological signal sensing biological signals. Using the PPG sensor to sense the bio-signal and the processor unit the signal obtained through the sensor by removing the motion artifact was able to alarm and monitoring the parent.The proposed system will send the alarm to monitoring and alerting caregivers if the risk situation by analyzing the heart rate of the infant. With the actual implementation of the system to evaluate the performance of the monitoring system.