• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.59-64
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• 2002

In this paper, 10$\mu$ m-elevated MEMS CPWs on various substrates are presented. Effective dielectric constants of elevated CPW(ECPW) on polyimide-loaded silicon or alumina substrate are examined and characteristic impedances are also computed versus elevation height. Dispersive property of ECPW and its electromagnetic field distributions are studied through 3-D FDTD algorithm for optimum design. Attenuation of ECPW is measured with TRL calibration procedure and revealed about 3.2 43 lower than that of conventional CPW on the same low-resistivity silicon at 40 CHz. ECPW on polyimide-loaded silicon with overlapped configuration reveals 0.2 dB/mm. Especially, alumina substrate imposes better attenuation than silicon.

• Journal of Electrical Engineering and information Science
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• 제2권4호
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• pp.72-78
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• 1997

A free space transmission method using standard gain horn antennas in the frequency range from 9.0 to 10.5GHz is applied to determine the dielectric properties of grain such as rough rice ,brown rice and barley. The dielectric constant and loss factor, which depend on the moisture content of the wetted grain are obtained from the measured attenuation and phase shift by vector network analyzer. The moisture content of grain varied from 11 to 25% based on this wetted condition. The measured values of dielectric constants as a function of moisture density are compared with values of those obtained using he predicted model for estimating dielectric constants of grain. The effect of density fluctuation, high is an important parameter governing the dielectric properties of grain, on the dielectric constant and loss factor is presented. A new density-independent model in terms of measured attenuation an moisture density is proposed of reducing the effects of density fluctuation on the moisture content measurement.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.200-201
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• 2002

Recently, a countermeasure for the electromagnetic noise emission on RF integrated transmission line using the loss generation of ferromagnetic thin films is briefly suggested$\^$1,2/. Without the magnetic film, the noise harmonics of the signal pass through the transmission line with only a little attenuation. The ideal role of magnetic film is not to raise insertion losses in the pass-band and to give as large attenuation as possible to eliminate the noise harmonics at the stop-band, the frequency range higher than the meaningful signal as shown in Fig. 1. and Fig. 2. (omitted)

• 전기학회논문지
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• 제56권8호
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• pp.1471-1475
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• 2007

In this paper, a novel embedded ultra wideband (UWB) band-pass filter is presented on a FR-4 package substrate including high Dk resin coated copper (${\varepsilon}_r=30$) film. The proposed UWB filter is comprised of a parallel resonator with meander-type uniform impedance resonator (UIR) and two series resonators with high Q circular stacked spiral inductor and metal-insulator-metal (MIM) capacitor. In order to obtain excellent attenuation characteristics by generating attenuation poles in lower and upper stop bands, a single MIM capacitor is added to each resonator. The fabricated FR-4 embedded UWB filter has insertion loss of -1.0dB and return loss of -11dB, respectively. It has also extremely wide bandwidth (over 50%) and small size ($3.7{\times}4{\times}0.77\;mm^3$) which is compatible with LTCC devices.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1399-1404
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• 2018

This study used an inductively coupled plasma (ICP) dry etching process with a metal amplitude mask to fabricate a double-side notched long-period fiber grating (DNLPFG) for loading sensing. The DNLPFG exhibited increasing resonance attenuation loss for a particular wavelength when subjected to loading. When the DNLPFG was subjected to force loading, the transmission spectra were changed, showing a with wavelength shift and resonance attenuation loss. The experimental results showed that the resonant dip of the DNLPFG increased with increasing loading. The maximum resonant dip of the $40-{\mu}m$ DNLPFG sensor was -26.522 dB under 0.049-N loading, and the largest force sensitivity was -436.664 dB/N. The results demonstrate that the proposed DNLPFG has potential for force sensing applications.

• Coupled systems mechanics
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• 제12권2호
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• pp.103-125
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• 2023

The present research is focused on the study of plane harmonic waves in a two-dimensional orthotropic magneto-thermoelastic media with fractional order theory of generalized thermoelasticity in the light of two-temperature and rotation due to time harmonic sources. Here, we studied three types of waves namely quasi-longitudinal (QL), quasi-transverse (QTS) and quasi thermal (QT) waves. The variations in the wave properties such as phase velocity, attenuation coefficient and specific loss have been noticed with respect to frequency for the reflected waves. Further the value of amplitude ratios, energy ratios and penetration depth are computed numerically with respect to angle of incidence. The numerical simulated results are presented graphically to show the effect of fractional parameter based on its conductivity (0<α<1 for weak, α=1 for normal, 1<α≤2 for strong conductivity) on all the components.

• 한국지진공학회논문집
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• 제3권1호
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• pp.67-74
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• 1999

이 연구에서는 단일 산란이론을 이용하여 경상분지에서 얻어진 국소 미소지진의 자료를 1.5-1.8Hz 사이의 주파수 영역에서 몇 개의 구간으로 나누어 대역 통과 필터링을 g여 coda 파의 진폭 감쇠로부터 Q값을 결정하였다 Coda Q 값은 Qc=Q0 fn 형태의 주파수 의존 양상을 보여주며 Q0 값은 83.9-155.9 n 값은 0.76에서 1.05 사이로 나타났다 산란 감쇠와 고유감쇠를 고려하여 감쇠가 순전히 산란에 의해서만 일어난다고 가정했을 때 최소 평균 자유경로를 51.-56km 이고 비탄성 감쇠계수는 0.0093-0.0098 로 나타났다 진앙과 관측소간의 경로가 단층지역을 지나는 것이 다른 경로를 지나오는 것보다 높은 감쇠와 강한 주파수 의존성을 보여준다.

• 한국지진공학회논문집
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• 제11권6호
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• pp.15-21
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• 2007

정확한 지진재해 예측을 위해서는 대상지역 특성을 고려하여 개발한 강진동 감쇠식을 사용해야 한다. 본 연구에서는 한반도의 감쇠식에 관한 기존연구에서 제시한 여러 감쇠식 및 지진자료를 비교한 후 그 유형이 가장 유사한 관계식을 선별하였다. 지진재해예측을 위한 HAZUS에서는 미국을 서부와 중동부로 구분한 강진동 감쇠식을 지원하는데, 앞서 선별한 국내 감쇠식과 부합하는 미국의 감쇠식 종류를 알아보았다. 이번 연구는 향후 HAZUS를 이용하여 한반도의 지진재해를 예측하고자 할 때, 우리나라의 감쇠현상과 가장 유사한 미국의 강진동 감쇠식을 사용함으로써 신뢰성 높은 재해예측에 효과적인 영향을 줄 것으로 기대한다.

• 한국세라믹학회지
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• 제28권6호
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• pp.483-487
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• 1991

Ferrite electromagnetic wave absorber whose attenuation ability are mainly relied on their magnetic loss, has been used in relatively narrow wave frequency ranges. In this study, we tried to produce a wide-range electromagnetic wave absorber by laminating sintered ferrite (Mn0.07Ni0.28Zn0.65Fe2O4) and dielectrics (Cordierite). We also investigated effects of dielectric constant and thickness on the attenuation behavior of the absorber. Applicable band width, in which the attenuation is greater than 20 dB can be widened from 100∼700 MHz of ferrite alone to 100∼900MHz by employing the laminated structure. Thickness of dielectrics to achieve wide-range application decreased as the dielectric constant increased.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.39-44
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• 2005

A broadband DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by newly inserted the transmission lines in conventional Switched-T attenuator and the optimization of the transmission line parameters. Momentum was employed in design for an accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify performance stability against the MMIC process variation. The attenuator has been fabricated with 0.15 $\mu$m GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic range. High attenuation accuracy has been achieved over all attenuation range and full 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies.