• E2M - 전기 전자와 첨단 소재
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• 제11권11호
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• pp.22-27
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• 1998

We have investigated the effect of an ion shower doping of the laser annealed poly-Si films at an elevated substrate temperatures. The substrate temperature was varied from room temperature to 300$^{\circ}C$ when the poly-Si film was doped with phosphorus by a non-mass-separated ion shower. Optical, structural, and electrical characterizations have been performed in order to study the effect of the ion showering doping. The sheet resistance of the doped poly-Si films was decreased from7${\times}$106 $\Omega$/$\square$ to 700 $\Omega$/$\square$ when the substrate temperature was increased from room temperature to 300$^{\circ}C$. This low sheet resistance is due to the fact that the doped film doesn't become amorphous but remains in the polycrystalline phase. The mildly elevated substrate temperature appears to reduce ion damages incurred in poly-Si films during ion-shower doping. Using the ion-shower doping at 250$^{\circ}C$, the field effect mobility of 120 $\textrm{cm}^2$/(v$.$s) has been obtained for the n-channel poly-Si TFTs.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.205-209
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• 2001

이 논문은 셀룰러와 PCS 대역에서 사용 가능한 전력 분배기를 설계하였다. 본 논문에서 설계한 전력 분배기는 2-way 소자로 각 포트 소자는 가역성을 가지므로 전력을 분배하는 경우 또는 합성하는 경우에 사용되는 소자이다. 2-way의 경우 50$\Omega$ 특성임피던스를 갖는 입력포트에 전력을 인가하여 전력의 크기와 위상이 동일하게 두 부분으로 분배되어 투 개의 출력포트에 나타난다. 일반적으로 3dB의 분배효과를 가지게 되지만 설계 시내부 손실을 가지게 된다. 본 논문에서는 내부손실을 최소화하여 광대역에서 균일한 내부손실을 가지도록 설계하고 또한 대역범위에서 양호한 isolation를 가지는 소자를 설계하는데 그 목적을 두었다.

• 한국광학회지
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• 제1권1호
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• pp.65-72
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• 1990

최대 10kJ의 에너지를 공급할 수 있는 Mather형 플라즈마 집속장치를 설계, 제작하였다. 이 DPF 장치의 전기 방전 특성을 알기 위해 Rogowski 코일을 제작하고 방전전류, 전압을 측정하여 본 system 의 저항과 인덕턴스는 각각 $20m\Omega과 0.2{\mu}H로 밝혀졌다. 플라즈마 전류 sheath의 이동속도는 충전개스 압력과 전압에 따라 $P^{-0.25}\timesV^{0.38}$의 함수로 비례하며 집속된 플라즈마의 크기는 직경 3mm, 길이 17mm로 밝혀졌다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.246-253
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• 2000

The optimal equations to predict the soil tempratures of twelve cities in the region of the southern part of the Korea such as Changhung, Cheju, Chinju, Kwangju, Masan, Miryang, Mokpo, Muan, Pusan, Sogwipo, Ulsan, Yoosu, were suggested as function of time and soil depth and the time dependent variation and soil depth dependent distribution of temperature were analyzed for the back data of the geothermal energy utilization system design and agricultural usages. The equation form is $T(x,\;t)\;=\;T_{m}\;-\;T_{so}{\cdot}Exp(-\xi){\cdot}cos{\omega}(t\;-\;t_{o}\;-\;x\;/\sqrt{2{\alpha}{\omega}}$) and it can predict the soil temperatures well with the correlation factor of 0.98 or upwards for most data. The range of mean soil temperature was $14.99~18.53^{\circ}C$ and soil surface temperature swing, 11.65~14.54 days, soil thermal diffusivity, $0.025~0.069\;m^2/day$ except Mokpo of $0.100\;m^2/day$, and phase shift, 19.66~27.81 days. During about thirty years from 1960s to 1990s, the mean soil temperature was increased by $0.04~1.25^{\circ}C$. The temperature difference depending on soil depth was not significant.

• 한국전기전자재료학회논문지
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• 제23권12호
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• pp.966-972
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• 2010

Single-phase $Sr_2FeMoO_6$ thin films were produced by RF magnetron sputtering for use as electrodes in integrated sensors and found to be good conductors at room temperature. The films were deposited from a powder-type sputtering target under various conditions, and were crystallized by annealing. Elimination of $O_2$ gas during deposition, by the use of a solely Ar sputtering gas under a working pressure as low as possible, and vacuum annealing were important to promote the $Sr_2FeMoO_6$ phase. However, oxygen exclusion from sputtering and annealing was not enough to yield single-phase $Sr_2FeMoO_6$: hydrogen annealing was also required. Film production was optimized by varying the deposition parameters and hydrogen annealing conditions. The film had good electrical conduction, with a low resistivity of $1.6{\times}10^{-2}\Omega{\cdot}cm$ at room temperature.

• The Korean Journal of Ceramics
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• 제2권1호
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• pp.25-32
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• 1996

Solid electroyte nasion was synthesized by the optimized solid state reaction minimizing the volume fraction of secondary $ZrO_2$ and glassy phases. To compensate for the evaporation of Na and P during heat-treatment, excess Na and P were added to the starting composition $Na_{1+x} Zr_2 Si_x P_{d-x} O_{12}$ (x=2.1). Phases pure nasicon comparable in volume fraction to the one obtaied from sol-gel process were synthesized after the reaction at $1100~1150^{\circ}C$,$ P_{O2}>=0.1-0.15 $$ZrO_2$ increased with the heat-treatment time due to the decomposition of nasicon phase and that of glassy phase increased as partial oxygen pressure decreased. The synthesized nasion showed a good electrical conductivity of $-1{\times}10^{-2}({\omega}{\cdot}cm)^{-1}$ at $350^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 추계학술대회 논문집
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• pp.22-27
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• 1992

Phosphorus doped hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin films were deposited by PECVD (Plasma Enhanced Chemical Vapour Deposition) method using 10.2% $SiH_4$ gas (diluted in Ar) and 308ppm $PH_3$ gas (diluted in Ar). The structural, optical and electrical properties of the films were investigated as a function of substrate temperature(15 to $400^{\circ}C$) and RF power(10 to 120W). The thin film deposited by varing substrate temperature had columnar structure and microcrystalline phase. The volume fraction of microcrystalline phase in the films deposited at RF power of 80W, increased with increasing substrate temperature up to $200^{\circ}C$, and then decreased with further increasing substrate temperature. Volume fraction of microcrystalline phase increased monotonously with increasing RF power at substrate temperature of $250^{\circ}C$. With increasing volume fraction of microcrystalline, electrical resistivity of films decreased to 0.274 ${\Omega}cm$.

• 한국염색가공학회지
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• 제8권1호
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• pp.56-63
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• 1996

A number of thermotropic liquid crystalline polyurethanes with mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 1, 4-phenylene diisocyanate(1,4-PDI) with 4, 4'-bis($\omega$-hydorxyalkoxy) biphenyls($BP{m}$) in DMF. The thermal and liquid crystab line properties were examined by differential scanning calorimetry(DSC), polarized optical microscopy, and wide-angle X-ray scattering(WAXS). Intrinsic viscosities of the polymers exbibited two endothermic peaks correspondinding to phase transitions of melting and isotropization. For example, polyurethane(1,4-PDI/($BP{11}$) ) was found to display a liquid crystalline phase between 177 to 205$^{\circ}C$. In order to know how the hydrogen bonding interaction affects the formation of mesophases in polyurethane 1, 4-PDI/($BP{8}$) / thermal processing FT-IR measurements were carried out. It was found that the stretches regarded as shift to higher frequency region with increasing temperature which showed grdually their liquid crystalline phase

• 한국재료학회지
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• 제1권3호
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• pp.168-174
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• 1991

Ti-Silicides를 single-Si wafer와 그 위에 oxide를 성장시킨 기판위에 composite target($TiSi_{2.6}$)을 sputtering함으로써 증착시켰다. 증착된 비정질 상태의 Ti-silicide는 급속 열처리(RTA)방법으로 $600^{\circ}C$에서 $850^{\circ}C$가지 20초간 처리하였다. RTA온도가 $800^{\circ}C$가 되어서야 비로소 안정한 $TiSi_2$가 형성되었으며, 그 때의 비저항 값은 $27~29{\mu}\Omega-cm$로 Ti-metal reactive방법에 의한 $TiSi_2$보다 약간 높은 값으로 드러났다. X-ray로 상천이를 조사한 결과 역시 $750^{\circ}C$가지 C49 $TiSi_2$가 형성되고, $800^{\circ}C$가 되어서야 안정한 C54 $TiSi_2$로의 상천이가 일어남을 나타내고 있다. 또한 완전히 형성된 Ti-silicide의 조성비는 x-ray photoelectron spectroscopy(XPS)결과에서 Ti : Si이 1 : 2로 드러났으며, 그 동안 reactive 시켰을 때 $TiSi_2$의 단점으로 지적되어 왔던 형성 완료된 $TiSi_2$의 surface roughness는 $17{\pm}1mm$이내로 매우 우수한 값으로 판명되어, device에 대한 응용 가능성을 높이고 있다.

• 한국전기전자재료학회논문지
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• 제31권5호
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• pp.307-312
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• 2018

Liquid phases in ZnO varistors cause more complex phase development and microstructure, which makes the control of electrical properties and reliability more difficult. Therefore, we have investigated 2 mol% $CaCO_3$ doped $ZnO-Co_3O_4-Cr_2O_3-La_2O_3$ (ZCCLCa) bulk ceramics as one of the compositions without liquid phase sintering additive. The results were as follows: when $CaCO_3$ is added to ZCCLCa ($644{\Omega}cm$) acting as a simple ohmic resistor, CaO does not form a secondary phase with ZnO but is mostly distributed in the grain boundary and has excellent varistor characteristics (high nonlinear coefficient ${\alpha}=78$, low leakage current of $0.06{\mu}A/cm^2$, and high insulation resistance of $1{\times}10^{11}{\Omega}cm$). The main defects $Zn_i^{{\cdot}{\cdot}}$ (AS: 0.16 eV, IS & MS: 0.20 eV) and $V_o^{\bullet}$ (AS: 0.29 eV, IS & MS: 0.37 eV) were found, and the grain boundaries had 1.1 eV with electrically single grain boundary. The resistance of each defect and grain boundary decreases exponentially with increasing the measurement temperature. However, the capacitance (0.2 nF) of the grain boundary was ~1/10 lower than that of the two defects (~3.8 nF, ~2.2 nF) and showed a tendency to decrease as the measurement temperature increased. Therefore, ZCCLCa varistors have high sintering temperature of $1,200^{\circ}C$ due to lack of liquid phase additives, but excellent varistor characteristics are exhibited, which means ZCCLCa is a good candidate for realizing chip type or disc type commercial varistor products with excellent performance.