• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.35-40
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• 2008

In this paper, a new analytical formulation is presented for calculating shielding effectiveness (SE) of shielding enclosure including satellite electronic components and equipments. The shielding enclosure has a dielectric-backed aperture. The SE may be a function of frequency, dielectric constant, and position within the enclosure. And, the formulation has been extended for calculation of the SE of the structure where the one side of dielectric is partially backed by conductor. Our simulation results give that the dielectric material lowers the Q factor, and the further the observation point is from the aperture, the more SE increases.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.9-10
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• 2012

AFD(Active Frequency Drift), SMS(Slip-Mode frequency Shift)를 비롯한 주파수 이동 단독 운전 검출 방법은 단독 운전 발생 후, 계통의 주파수를 정상 운전 범위 밖으로 이동시켜 OUF(Over/Under Frequency) 릴레이를 동작하게 만들어 단독 운전을 검출한다. 이 방법들의 불검출 영역은 알고리즘에 의한 전류 위상각 변화율과 부하 역률 각 변화율 사이의 관계, 그리고 단독 운전 후 정상 상태(steady state) 운전 주파수에 의해 결정된다. 본 논문에서는 불검출 영역에 영향을 미치는 부하 역률 각 변화율을 분석하고 그를 바탕으로, 설계한 Q(Quality)-factor보다 낮은 Q-factor를 갖는 부하 조건에서는 항상 단독 운전을 검출할 수 있는 설계 방법을 제시한다. 제안된 방법의 유효성은 모의실험 및 실험으로 검증되었다.

• ETRI Journal
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• v.28 no.4
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• pp.529-532
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• 2006

This letter describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in coplanar waveguide (CPW) technology. The high quality (Q)-factor and spurious-free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator showed a loaded Q-factor of 180 in a chip area of only 40% of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed an additional phase noise reduction of 10.5 dB at a 1 MHz offset and a second harmonic suppression enhancement of 6 dB when compared to those of a conventional CPW oscillator without the planar helical resonator structure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.376-380
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• 2005

The paper presents some methods to improve characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on Bragg reflectors. Thermal treatments were done by sintering and/or annealing processes. The measurement showed a considerable improvement of return loss (S$_{11}$) and quality factor (Q$_{s/p}$). These thermal techniques seem very promising for enhancing FBAR resonance performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.311-315
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• 2005

In this paper, we emphasize the advantage of thermal annealing treatments for improvement characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on multi-layer thin films, namely, Bragg reflectors. Sintering and/or annealing processes were applied in our experiments. The measurements confirm once again a considerable improvement of return loss $(S_{11})$ and quality factor $(Q_{s/p})$. these thermal treatment techniques are really promising for enhancing performance of FBAR resonators in industry fabrication of RF devices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.59-62
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• 2008

In this paper, we study ZnO-based a film bulk acoustic resonator (FBAR) using a multi-layered Bragg reflector. We insert chromium adhesion layers of 0.03 mm-thick to the Bragg reflector and improve the performance using thermal treatments. At operating frequency about 2.5 GHz, excellent resonance characteristics are observed in terms of good return loss and high quality factor.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.19-24
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• 2003

A very small size 2.4 GHz ISM band BPF(Band Pass Filter) is realized using LTCC Multi-layer technology. Proposed design method enables to achieve BPF size $2.0\times1.2\times0.8mm^3$. A $lambda/4$ resonator with shunt-to-ground loaded capacitor is used to shorten resonator length, achieving higher quality factor. Also this resonator enables BPF to improve out-of-band rejection. Coupling coefficients between coupled strip-line resonators and external quality factor (Qe) of a resonator are derived and applied to the filter design. The measured results show good agreement with simulated data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1148-1151
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• 2002

Dielectric ceramics with nominal composition of $(Ba_{0.93}Sr_{0.07}O)-0.5Sm_2O_3-4.5TiO_2$ was prepared using the conventional mixed oxide process-derived powder. Effect of $SiO_2$, $MnO_2$ and $Al_2O_3$ impurity addition on the microwave properties was examined in some detail. Measured relative permittivity $(\varepsilon_r)$ values were in the range of 53 to 59 and showed little dependence on impurity addition. In contrast, quality factor $(Q{\cdot}f)$ and temperature coefficient of resonant frequency $(\tau_f)$ values were greatly influenced by the type and the amount of impurities. It was found that 0.1~0.2wt% addition of $Al_2O_3$ was most effective for improving the properties, where ${\varepsilon}_r$, $Q{\cdot}f$ and $\tau_f$ values were 57.7, 10000, and +7ppm/$^{\circ}C$, respectively.

• Journal of Magnetics
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• v.20 no.4
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• pp.347-352
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• 2015

The magnetoelectric (ME) characteristics for Terfenol-D/PZT laminate composite dependence on bias magnetic field is investigated. At low frequency, ME response is determined by the piezomagnetic coefficient $d_{33,m}$ and the elastic compliance $s_{33}^H$ of magnetostrictive material, $d_{33,m}$ and $s_{33}^H$ for Terfenol-D are inherently nonlinear and dependent on $H_{dc}$, leading to the influence of $H_{dc}$ on low-frequency ME voltage coefficient. At resonance, the mechanical quality factor $Q_m$ dependences on $H_{dc}$ results in the differences between the low-frequency and resonant ME voltage coefficient with $H_{dc}$. In terms of ${\Delta}E$ effect, the resonant frequency shift is derived with respect to the bias magnetic field. Considering the nonlinear effect of magnetostrictive material and $Q_m$ dependence on $H_{dc}$c, it predicts the low-frequency and resonant ME voltage coefficients as a function of the dc bias magnetic field. A good agreement between the theoretical results and experimental data is obtained and it is found that ME characteristics dependence on $H_{dc}$ are mainly influenced by the nonlinear effect of magnetostrictive material.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.178-182
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• 2003

This paper presents the embedded inductors in PCB (Printed Circuit Board) for PAM(Power Amplifier Module) of mobile terminations. The inductors are designed, simulated, and compared to conventional chip inductors. The Quality factor(Q) and self-resonance frequency(SRF) of the inductors are evaluated. The quality factors of the inductors are two times higher than those of the chip inductors, and the self-resonance frequency is 1.3 times higher than those of chip inductors at the inductance of 2.7 nH and 3.3 nH respectively.