• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.1
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• pp.33-39
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• 1979

The resonance frequency of the slot-line resonator in the shielding box is analyzed. It is verified experimentally that an X-Band oscillator may be realized by the resonator in the microstrip circuit mount as a shielding cavity, and by shunt-connecting the IMPACT diode on the slot-line, And the oscillating power can be coupled with the microstrip by the coupling aperure on the opposite surface of the microstrip by the coupling aperure on the opposite of the substrate of the microstrip cirsuit.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.67-73
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• 2008

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different within various regions. In addition, it makes it possible for a single mobile handset to support various standards of wireless communication, and thus plays a key role inmobile convergence. A MMIC VCO(Monolithic Microwave Integrated Circuit Voltage Controlled Oscillator) has been developed to produce high power and wide bandwidth that adapts the Clapp-Gouriet type oscillator for series feedback. We were fabricated based on the 0.15um pHEMT from TRW. The MMIC VCO was connected to an alumina substrate on the carrier for testing. This MMIC VCO module shows good performance when compared with existing VCOs. Futhermore, it has potential as a reconfigurable MMIC VCO for ubiquitous communications such as LMDS (Local Multipoint Distribution Service), VSAT, Point to Point Radio and SATCOM.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.185-188
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• 2001

In this paper, we design and implement high-power amplifier with 18 watt for W-CDMA repeater. We simulate microwave circuits using RF simulator, ADS1.3 and optimize the circuit to obtain the linear and high power using Harmonic balance method. Harmonic balance is an excellent method in the analysis of nonlinear system. The HPA is fabricated on tefron substrate($\varepsilon_{{\gamma}}$=3.48, h=0.5mm, T=0.035mm). From the measured result, the HPA has gain of 52dB, 1 dB compression power of 52.8dBm and good ACPR (Adjacent Channel Power Radio) performance.l Power Radio) performance.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.630-637
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• 2003

In this paper, a DBM(double balanced mixer) of 2 GHz is implemented on FR4(h=1.6mm, ${\epsilon}_r=4.6$) substrate. The structure of double balanced mixer requires, in general, two talons and a quad diode. For balun, a novel planar balun using microstrip to CPS(Coplanar Strip) is suggested and designed. The suggested balun shows the phase imbalance of $180^{\circ}{\pm}1.5^{\circ}$ and the amplitude imbalance of ${\pm}0.2 dB$ for 1.5 to 2.5 GHz. Using the balun, DBM is successfully implemented, and the measured conversion loss of up/down converter show about 6 dB over the bandwidth. The balun may be applicable for MMIC(Monolithic Microwave Integrated Circuit) DBM with the process supporting backside via though more study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.382-385
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• 2001

In the previous study, a new LTCC material in the $PbWO_{4}-TiO_{2}-B_{2}O_{3}-CuO$ system was introduced. The developed material can be sintered at $850^{\circ}C$ and its dielectric properties are $\varepsilon_{r}=20-25$, $Q{\times}f_{o}=30000\sim50000GHz$, and $\tau_{f}=0.2{\sim}30ppm/^{\circ}C$, respectively. Therefore this material can be used as a LTCC substrate material for fabrication of multilayered high frequency communication module set. In present study, using this material, tape casting condition was established. With this condition, a multilayered resonator was fabricated and its electrical properties were examined. In present study, an antenna-duplexer module was also fabricated. Frequency characteristics of as-fabricated antenna-duplexer module was compared with simulation results.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1542-1545
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• 2002

Experimental works were performed to implement the hetero-epitaxial growth of diamond films on the (100)- and (111)-oriented Si substrates. The deposition process used to prepare diamond films consisted of a bias-enhanced nucleation(BEN) step, accompanied with a growth step using a microwave plasma CVD system. The highly oriented diamond films were deposited under the growth condition of relatively low methane concentrations and high temperatures. Material properties and surface morphologies of deposited diamond films were improved by the addition of carburization step into the deposition process.

• Progress in Superconductivity
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• v.1 no.1
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.305-305
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• 2015

알루미늄 방열판 위에 MPCVD(Microwave Plasma Enhanced Chemical Vapor Deposition) 장치를 이용하여 DC 바이어스 전압을 기판에 인가하면서 $Ar+CH_4$ 가스 분위기에서 증착한 나노결정질 다이아몬드(Nanocrystalline Diamond; NCD) 박막의 방열 특성을 평가하였다. XRD와 Raman spectroscopy를 이용하여 증착된 박막이 NCD인지를 확인하였으며 FE-SEM 및 FIB로 박막의 표면 및 단면의 형상을 관찰하였다. 다이아몬드가 증착된 방열판에 LED를 부착하여 발열시키고 열유동측정기의 하나인 T3-ster를 사용하여 방열 특성을 분석하였다. 기존 알루미늄(Al) 기판(5.55 K/W)보다 다이아몬드 증착(Dia-Al) 기판(3.88 K/W)의 열저항 값이 현저히 작았다, 또한 LED 접합온도는 Dia-Al 기판이 Al 기판보다 약 $3.5^{\circ}C$만큼 낮았다. 적외선 열화상 카메라로 발열 중인 시편의 전면과 후면을 촬영한 결과, LED가 부착된 전면부에서는 최고 발열 부위(hot spot)의 면적이 Al 기판의 경우가 Dia-Al 기판보다 높았고, 후면부에서는 그 반대의 경향을 보였다. 이들 데이터로부터 다이아몬드 증착 방열판이 기존의 방열판보다 방열특성이 우수한 것으로 해석할 수 있으며, 다이아몬드 박막을 방열판으로 사용하면 LED의 사용 수명과 효율이 높아질 것으로 기대된다.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.18-20
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• 1997

The fabrication process of silicon-diamond(SOD) structure wafer were studied. Microwave plasma chemical vapor deposition (MWPCVD) and annealing technology were used to synthesize diamond film with high resistivity and thermal conductivity. Bonding and etchback silicon-on-diamond (BESOD) were utilized to form supporting substrate and single silicon thin layer of SOD wafer. At last, a SOD structure wafer with 0.3~1$\mu\textrm{m}$ silicon film and 2$\mu\textrm{m}$ diamond film was prepared. The characteristics of radiation for a CMOS integrated circuit (IC) fabricated by SOD wafer were studied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.366-369
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• 1999

Synthetic diamond films have been deposited on the silicon(100) surface and molybdenum substrates using an microwave plasma enhanced vapor deposition (MWPECVD) method. The effect of deposition time, surface morphology, X-ray diffraction pattrm, infrared transmittance and Raman Scattering have been studied, The diamond film deposited on Mo substrate for (100) hours at 40 torr H$_2$-CH$_4$O$_2$ gas system have been shown 1${\mu}{\textrm}{m}$/h of growth rate and good crystallization