• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.273-280
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• 2021

This paper presents the results of study of linear oscillating electric machine; Cartesian, cylindrical type with permanent magnet, flux reversal, cylindrical reluctance, and transverse flux type. The focus of the work is the suggestion of the characteristics and design process of propose topology, respectively. First of all, there are five types of the proposed to this study on the basis of the existing literatures; Cartesian type, cylindrical type, flux reversal type, cylindrical reluctance type, and transverse flux type. All topology is achieved using equivalent magnetic circuit considering leakage elements as initial modeling. Cartesian type is investigated by number of phases and number of pole pairs using optimal process. A cylindrical type is described by number of phases and displacement of stroke. The flux reversal type is proposed based on the symmetrical and non symmetrical stator cores of the surface mounted PMs mover, and non slanted PMs and slanted PMs of the flux concentrating PMs mover. A cylindrical reluctance type is studied by the shape of mover teeth in geometric aspect to reduce force ripple and increase magnetic flux. A transverse flux type is considered by dividing the transverse flux electric excited and the transverse flux permanent magnet excited. It is significant that the study gives a design rules and features of linear oscillating electric machine.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.25-32
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• 2021

In this paper, the Magneto-Electric(ME) dipole array antenna with dual-polarization in the X-Band is proposed and it is implemented and measured. The proposed array antenna is composed of 32 single ME dipole antenna and a Teflon PCB. 1 × 1 ME dipole antenna is implemented dual-polarization by radiating vertical polarization and horizontal polarization from two pairs of radiators. 2-port feeding structures are realized by lamination process using LTCC. And, each port independently feeds the radiator through a Γ-shaped feeding strip with isolation between ports. The Teflon PCB used in the antenna array has a 4-layer structure, and 2-port is fed through the top and bottom layers. The λ_g/4 transformer is applied to the transmission line of the Teflon PCB for impedance matching of the arrayed antenna and the Teflon PCB, and the optimal parameters are obtained through simulation. The measured maximum antenna gains of port 1 was 18.2 dBi, Cross-pol was 1.0 dBi. And the measured maximum antenna gains of port 1 was 18.1 dBi, Cross-pol was 3.2 dBi.

• Korean Journal of Remote Sensing
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• v.35 no.6_3
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• pp.1235-1249
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• 2019

Kilauea Volcano is one of the most active volcano in the world. In this study, we used the ALOS-2 PALSAR-2 satellite imagery to measure the surface deformation occurring near the summit of the Kilauea volcano from 2015 to 2017. In order to measure two-dimensional surface deformation, interferometric synthetic aperture radar (InSAR) and multiple aperture SAR interferometry (MAI) methods were performed using two interferometric pairs. To improve the precision of 2D measurement, we compared root-mean-squared deviation (RMSD) of the difference of measurement value as we change the effective antenna length and normalized squint value, which are factors that can affect the measurement performance of the MAI method. Through the compare, the values of the factors, which can measure deformation most precisely, were selected. After select optimal values of the factors, the RMSD values of the difference of the MAI measurement were decreased from 4.07 cm to 2.05 cm. In each interferograms, the maximum deformation in line-of-sight direction is -28.6 cm and -27.3 cm, respectively, and the maximum deformation in the along-track direction is 20.2 cm and 20.8 cm, in the opposite direction is -24.9 cm and -24.3 cm, respectively. After stacking the two interferograms, two-dimensional surface deformation mapping was performed, and a maximum surface deformation of approximately 30.4 cm was measured in the northwest direction. In addition, large deformation of more than 20 cm were measured in all directions. The measurement results show that the risk of eruption activity is increasing in Kilauea Volcano. The measurements of the surface deformation of Kilauea volcano from 2015 to 2017 are expected to be helpful for the study of the eruption activity of Kilauea volcano in the future.

• Neonatal Medicine
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• v.18 no.2
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• pp.320-327
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• 2011

Purpose: To determine the effect of changing practice guidelines designed to avoid hyperoxia or hypoxia in very low birth weight or very preterm infants. Methods: We analyzed a database of <1,500 g birth weight or <32 weeks of gestation infants who were born and admitted to the neonatal intensive care unit of Chungnam National University Hospital from January 2007 to July 2010. First, we defined the relationship between arterial partial pressure of oxygen ($PaO_2$) and pulse oxygen saturation ($SpO_2$). When we evaluated 96 pairs of $PaO_2$ and $SpO_2$ measurements, oxygen saturation was 90-94% at a $PaO_2$ of 43-79 mmHg on the oxyhemoglobin dissociation curve, according to pulse oximetry. Based on this observation, a change in practice was instituted in August 2008 with the objective of avoiding hypoxia and hyperoxia in preterm infants with targeting a $SpO_2$ 90-94% (period II). Before the change in practice, high alarms for $SpO_2$ were set at 100% and low alarms at 95% (period I). Results: Sixty-eight infants the met enrollment criteria and 38 (56%) were born during period II, after the change in $SpO_2$ targets. Demographic characteristics, except gender, were similar between the infants born in both periods. After correcting for the effect of confounding factors, the rates for mortality, severe retinopathy of prematurity, and IVH attended to be lower than those for infants in period II. No difference in the rate of patent ductus arteriosus needed to treat was observed. Conclusion: A change in the practice guidelines aimed at avoiding low oxygen saturation and hyperoxia did not increase neonatal complication rates and showed promising results, suggesting decreased mortality and improvements in short term morbidity. It is still unclear what range of oxygen saturation is appropriate for very preterm infants but the more careful saturation targeting guideline should be considered to prevent hypoxemic events and hyperoxia.