• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.457-460
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• 2014

Precession coefficient is defined by the ratio of the angular rate or rotational angle of the standing wave formed in an elastic resonator with respect to that of the platform. In this paper the precession of a hemispherical resonator due to Coriolis' effect is studied through Rayleigh-Ritz's method and Lagrangian Mechanics when the resonator undergoes Rayleigh's mode deformation. The calculation result was compared with studies by other researchers.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.8
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• pp.384-389
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• 2005

The Resonance Scattering Theory(RST) provides the physical explanation of the scattered field that appears in the vicinity of the resonance frequency. The theory suggests that the amplitude of each Partial-wave mode can be divided into two components : resonance and non-resonant background. The long-standing difficulty in the application of RST is that it always requires background components. We have applied the RST to the electromagnetic scattering problems by a penetrable spherical scatterer and a cavity. In this paper, we show some numerical results, and validate background coefficients.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.575-578
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• 1995

X-ray magnetic-circular-dichroism (MCD) spectra, orbital ($$) and spin magnetic moments ($$) for Co(110) monolayers a free standing mode or sandwiched between Pd(Pd/1Co/Pd)and Cu layers (Cu/1Co/Cu) are calculated using the thin film full potential linearized augmented plane wave energy band method. In contrast to the double peak structure predicted for the Co(0001) surface, only a minor side peak is found in the MCD spectra for Cu/Co/Cu, while MCD spectra for the other systems show a single peak structure. The MCD sum rules originally derived from a single ion model are found in the band approach to be valid for the systems investigated. However, for the spin sum rule, the magnetic dipole term ($$) is not negligible and needs to be included.

• Journal of IKEEE
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• v.16 no.4
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• pp.297-303
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• 2012

This paper proposes the effective design procedure for a broadband, double-ridged horn antenna for evaluating the performance of the RF energy harvesting system with a multi-band rectenna. Using multi-mode network analysis, the higher-mode scattering parameters of the transition and horn were acquired and applied to the antenna design, respectively. As a result, the computing time could be reduced and the calculated VSWR(voltage standing wave ratio) of the antenna was very similar to the analyzed result using fully electromagnetic simulation. And there was also good agreement between the simulated and measured results. The designed broadband antenna has a bandwidth of 660~6360 MHz and 6~13.7 dBi peak radiation gain.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.40.3-40.3
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• 2010

The most frequently suggested source for Pi2 pulsations in the inner magnetosphere (L < 4) is standing fast-mode waves trapped in the plasmasphere (i.e., plasmaspheric resonances). They have been considered as the source of low-latitude Pi2 pulsations. The plasmaspheric resonance model suggests that compressional fast-mode waves can be detected at all local times inside the plasmasphere provided reflection of the wave energy is efficient. Until now, however, there are no reports about compressional Pi2s observed in the dayside inner magnetosphere. That is, there is longitudinal limit of inner magnetosphere. In February 2008, THEMIS probes were near dawn and/or dusk sides, which are the transition regions between the nightside and dayside, in the inner magnetosphere (L = 2-4) when low-altitude Pi2s were identified at Bohyun (L = 1.35) station in Korea. Using the THEMIS electric field data, we examined if Pi2s are excited by longitudinally localized disturbances. We found that compressional Pi2s having high coherence with a low-latitude Pi2 pulsation occur on dawnside. However, any compressional pulsations in the Pi2 frequency band were not detected on duskside. This indicates that compressional Pi2s disappear near the duskside. Our observations are discussed with spatial plasmaspheric structure and possible Pi2 mechanisms.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.227-234
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• 2018

Researches regarding measurement and control of the dynamic behavior of liquid such as sloshing have been actively on undertaken in various engineering fields. Liquid vibration is being measured in the study of tuned liquid dampers(TLDs), which attenuates wind motion of buildings even in building structures. To overcome the limitations of existing wave height measurement sensors, a method of measuring liquid vibration in a TLD using a laser Doppler vibrometer(LDV) and galvanometer scanner is proposed in this paper: the principle of measuring speed and displacement is discussed; a system of multi-point measurement with a single point of LDV according to the operating principles of the galvanometer scanner is established. 4-point liquid vibration on the TLD is measured, and the time domain data of each point is compared with the conventional video sensing data. It was confirmed that the waveform is transformed into the traveling wave and the standing wave. In addition, the data with measurement delay are cross-correlated to perform singular value decomposition. The natural frequencies and mode shapes are compared using theoretical and video sensing results.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.263-270
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• 2016

This paper implemented an ultra-wideband(: UWB) antenna by using a modified barrel-shaped patch antenna. The designed UWB patch antenna was optimized to match UWB technical specifications by considering the sizes of barrel circle and oval(notch) which is distance between the patch and contact surface and designed antenna was implemented by $10mm(R1){\times}21.8mm$ size. Optimal values on the basis of simulated reflective loss results, the surface current distribution of designed patch antenna was analyzed in order to check operation mode of antenna and wideband mechanism. Experimental results of implemented UWB antenna, Return loss of UWB antenna the voltage standing wave ratio was 2 or less in the 1.775-13.075 GHz band, VSWR in 2 or less. And the maximum gain of approx. 1-3 dBi was found in 3.1-10.6 GHz. This result satisfied the characteristics of ultra-wideband and the proposed antenna will be applicable to an ultra-wideband system.