• 한국전기전자재료학회논문지
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• 제14권6호
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• pp.481-486
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• 2001

ZnO thin films on glass substrate were depostied by RF magnetron reactive sputter with various argon/oxygen gas ratios and substrate temperatures. Crystallinities, surface morphologies, chemical compositions, and electrical properties of the films were investigated by XRD, SEM, XPS and electrometer(keithley 617). All films showed a strong preferred orientation along the c-axis on glass substrate, and the chemical stoichiometry was obtained at Ar/O$_2$.=50/50. The propagation velocity of ZnO SAW filter was about 2,590 m/sec and insertion loss was a minimum value of abut -21dB.

• 전자공학회논문지A
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• 제33A권12호
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• pp.33-38
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• 1996

In this paper, we modeled the complex dielectric constant and analyzed the projpagation characteristics of a FR-4 composite substrate with different compositions. From the wideband dielectric modeling and the propagation loss analysis of FR-4 composites that consists of FR-4 resin and E-glass reinforcement,we have found that the propagation loss and velocity increase with the volume fraction of FR-4 resin above 1 GHz. These results are helpful in determining to deisgn optimum substrate composition ratio and cross-sectional geometry of high-speed and high-density transmission line.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1502-1503
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• 2007

In this paper, inductive coupled LC balun has been desi gned and simulated for embedding into an organic packaging substrate. Inductive coupling method was applied to obtain wide band characteristics, and high dielectric film was utilized to reduce a size of the balun. The proposed balun has a novel scheme which consists of three embedded LC resonators with inductive coupling. This proposed balun has relatively small inductance and capacitance values which can be easily embedded into the organic packaging substrate. Furthermore, it has a good phase imbalance characteristic. The simulated results of proposed balun are an insertion loss of 1.2 dB, a return loss of 10 dB, a phase imbalance of 1 degree at frequency bandwidth of 750 MHz ranged from 1.8 GHz to 2.55 GHz, respectively. This balun has an area of $2mm{\tims}3.5mm{\times}0.66mm$ (height).

• ETRI Journal
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• 제45권2호
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• pp.338-345
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• 2023

A filtering power divider based on air-filled substrate-integrated waveguide (AFSIW) technology is proposed in this study. The AFSIW structure is used in the proposed filtering power divider for substantially reducing the transmission losses. This structure occupies a large area because of the use of air as a dielectric instead of typical dielectric materials. A filtering power divider provides power division and frequency selectivity simultaneously in a single device. The proposed filtering power divider comprises three AFSIW cavities. The filtering function is achieved using symmetrical inductive posts. The input and output ports of the proposed circuit are realized by directly connecting coaxial lines to the AFSIW cavities. This transition from the coaxial line to the AFSIW cavity eliminates the additional transitions, such as AFSIW-SIW and SIW-conductor-backed coplanar waveguide, applied in existing AFSIW circuits. The proposed power divider with a second-order bandpass filtering response is fabricated and measured at 5.5 GHz. The measurement results show that this circuit has a minimum insertion loss of 1 dB, 3-dB fractional bandwidth of 11.2%, and return loss exceeding 11 dB.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.22-26
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• 2007

Superconductor is weak in AC condition. Bifilar geometry provides a solution to reduce AC loss. Bifialr geometry is piled up or wound with more than two layers. When a layer of superconductor abuts on other layers, AC loss is affected by not only self-field, but also magnetic field induced by adjacent layers. In this study, two superconductors are piled up as a series connection so that current flows in different directions. By this method, magnetic field is cancelled. If magnetic field is cancelled, AC loss is reduced. To compare AC loss with respect to piling method, we measured the AC loss difference between the case facing each other with substrate side and the case facing with YBCO side. Measured AC loss is compared with one-way current flow single layer AC loss. In addition, we analyzed how much AC loss was increased, or reduced. All results were compared with those calculated with Norris equation. By this experiment, we concluded that distance between two wires is the important cause of AC loss. The distance between two wires affects magnetic field reduction in YBCO and induced current flow on substrate side.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1237-1241
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• 2003

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes lot vortical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. The packaged RF device has a reflection loss under 22 〔㏈〕 and a insertion loss of -0.04∼-0.08 〔㏈〕. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.

• 대한기계학회논문집
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• 제19권11호
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• pp.3072-3083
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• 1995

The numerical simulation on the three-dimensional natural convection heat transfer in the enclosure with heat generating chip is performed, and the effects of convective heat loss and vents are also examined. The effects of the Rayleigh number and outer Nusselt number (Nu$_{0}$) on the maximum chip temperature and the fractions of heat loss from the hot surfaces are investigated. The results show that conduction through the substrate is dominant in heat dissipation. With the increase of Rayleigh number, heat dissipation through the chip surfaces increases and heat loss through the substrate decreases. Maximum dimensionless temperature with vents is found to decrease about 40% compared to the one without vents at Nu$_{0}$=0.l. It is also shown that effects of size and location of the vents are negligible.ble.

• 한국재료학회지
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• 제27권2호
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• pp.107-112
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• 2017

The BCBJ (Back Contact and Back Junction) or back-lit solar cell design eliminates shading loss by placing the pn junction and metal electrode contacts all on one side that faces away from the sun. However, as the electron-hole generation sites now are located very far from the pn junction, loss by minority-carrier recombination can be a significant issue. Utilizing Medici, a 2-dimensional semiconductor device simulation tool, the interdependency between the substrate thickness and the minority-carrier recombination lifetime was studied in terms of how these factors affect the solar cell power output. Qualitatively speaking, the results indicate that a very high quality substrate with a long recombination lifetime is needed to maintain the maximum power generation. The quantitative value of the recombination lifetime of minority-carriers, i.e., electrons in p-type substrates, required in the BCBJ cell is about one order of magnitude longer than that in the front-lit cell, i.e., $5{\times}10^{-4}sec$ vs. $5{\times}10^{-5}sec$. Regardless of substrate thickness up to $150{\mu}m$, the power output in the BCBJ cell stays at nearly the maximum value of about $1.8{\times}10^{-2}W{\cdot}cm^{-2}$, or $18mW{\cdot}cm^{-2}$, as long as the recombination lifetime is $5{\times}10^{-4}s$ or longer. The output power, however, declines steeply to as low as $10mW{\cdot}cm^{-2}$ when the recombination lifetime becomes significantly shorter than $5{\times}10^{-4}sec$. Substrate thinning is found to be not as effective as in the front-lit case in stemming the decline in the output power. In view of these results, for BCBJ applications, the substrate needs to be only mono-crystalline Si of very high quality. This bars the use of poly-crystalline Si, which is gaining wider acceptance in standard front-lit solar cells.

• 전자공학회논문지
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• 제51권7호
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• pp.49-59
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• 2014

개구면 결합 마이크로스트립 패치 안테나(aperture coupled microstrip patch antenna; ACMPA)의 급전 기판의 유전상수와 두께가 안테나 대역폭과 방사특성에 미치는 영향에 대하여 연구하였다. 급전 기판의 두께가 같은 여러 가지 유전상수의 급전기판을 가지는 ACMPA의 최적화된 반사손실 대역폭은 방사특성의 저하 없이 급전기판의 유전상수가 감소할수록 대역폭이 증가한다. MMIC(monolithic microwave integrated circuit)와 집적화가 가능한 높은 유전상수(${\epsilon}_r=10$)를 가지는 급전 기판을 사용한 ACMPA의 최적화된 반사손실 대역폭은 방사특성의 저하 없이 급전 기판의 두께가 감소할수록 대역폭이 증가한다. 따라서 ACMPA는 MMIC와 집적화하기에 좋은 구조를 가진 패치 안테나이다.

• 한국전자파학회논문지
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• 제24권3호
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• pp.270-277
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• 2013

본 논문에서는 초고주파 대역에서 활용 가능한 ridge 기판 집적 도파관(RSIW:Ridge Substrate Integrated Waveguide)과 기판 집적 도파관(SIW: Substrate Integrated Waveguide) 간의 전이 구조를 제안한다. 제안된 전이 구조는 일정한 간격으로 도통 비아를 삽입하여 임피던스 정합과 전계 정합을 하였으며, 광대역 정합 특성을 갖는다. 측정 결과에서 20 dB 이하의 반사 손실 대역이 9.21~12.41 GHz이고, 중심 주파수 11 GHz 기준으로 비대역폭이 29.1 %임을 확인하였다. 또한, 가용 대역폭에서 급전 선로 부분을 제외한 전이 구조만의 삽입 손실은 최대 0.49 dB이다.