• Proceedings of the KWS Conference
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• 2000.10a
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• pp.240-242
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• 2000

This study was investigated absorption properties of electromagnetic wave in thermal sprayed Sr-ferrite coatings. The experiment of this study was ; manufactured thermal spraying powder for improving absorption-efficiency, processed for increasing strength of thermal spray coatings, and measured the electromagnetic wave shielding efficiency. This study was obtained excellent absorption-efficiency by thermal sprayed Sr-ferrite coatings.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.14-15
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• 2000

We study the microwave characteristics of traveling-wave photodetector using the finite-difference time-domain method. We present two parameters for design, the width of PIN region and the thickness of i-layer, and analyze TWPD's property in frequency domain.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.70.6-71
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• 2008

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.146-149
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• 2008

Simulation and signal conditioning on the time domain surface elevation records are conducted to verify the proposed Welch's method in non-directional ocean wave spectrum analysis. These spectrum data are further conditioned to provide wave characteristic that better describe the sea states. Comparison of significant wave height and zero crossing period between the proposed method and a reference toolkit are presented.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.454-461
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• 2008

This embedded module measures significant wave height and zero crossing periods through spectral energy from a record of time series heave motion. An ARM7TDMI core microcontroller serves as the main control unit which performs the appropriate control and signal conditioning. Monitored wave characteristic is transmitted with satellite modem. Mathematical equations on signal conditioning and experiments procedures are documented in this paper.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.835-841
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• 2011

Wave power generation systems operated in the ocean, has been developed as large power and grid power connection systems in general. However, small wave power generation systems offer operational efficiency for the lighted (navigation aids) buoy. They simply adopts a full-wave rectification for charging battery (direct connection method). In this paper, a wave power controller based on a booster converter is developed by considering a characteristic of the wells turbine. Both direct connection and booster converter power controller is designed and tested to compare the characteristics. Experiments demonstrate that the output of the proposed controller has improved the characteristic of output power, when generator output voltage is low.

• Atmosphere
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• v.23 no.4
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• pp.401-412
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• 2013

East Asia experienced extremely cold weather in January 2011, while the previous December and the following February had normal winter temperature. In this study National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data are used to investigate the characteristic features observed in the meteorological fields such as temperature, sea-level pressure, geopotential height, and wind during this winter period. In January the planetary-wave pattern is dominated by stationary-wave form in the mid-to-high latitude region, while transient waves are significant in the previous month. To understand the planetary-wave features quantitatively, harmonic analyses have been done for the 500-hPa geopotential height field. In the climatological-mean geopotential heights the wave numbers 1, 2, and 3 are dominant during the whole winter. In January 2011 the waves of number 1, 2, and 3 are dominant and stationary as in the climatological-mean field. In December 2010 and February 2011, however, the waves of number 4, 5, and 6 play a major role and show a transient pattern. In addition to the distinctive features in each month the planetary-wave patterns dependent on the latitude are also discussed.

• Bulletin of the Korean Mathematical Society
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• v.50 no.1
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• pp.201-216
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• 2013

In this note, we consider the Riemann problem for a two-dimensional nonstrictly hyperbolic system of conservation laws. Without the restriction that each jump of the initial data projects one planar elementary wave, six topologically distinct solutions are constructed by applying the generalized characteristic analysis method, in which the delta shock waves and the vacuum states appear. Moreover we demonstrate that the nature of our solutions is identical with that of solutions to the corresponding one-dimensional Cauchy problem, which provides a verification that our construction produces the correct global solutions.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.745-747
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• 2001

This paper deals with the dynamic characteristics of flat core LOA. The LOA system was represented by the voltage equation of coil and the mechanical equation of motion. Also, driving system was simply composed voltage source inverter and generates square-wave. It is measured that dynamic characteristic vary as square-wave.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.259-261
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• 1999

An operational transconductance amplifier (OTA) based precision full-wave rectifier circuit is presented in this article. The proposed circuit has a very sharp corner in the DC transfer characteristic and simple configuration comprised three OTAs and one current mirror. The temperature dependence of the OTA transconductance is reduced. Experimental results demonstrating the characteristic of the circuit are included.