• Elastomers and Composites
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• v.39 no.1
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• pp.12-22
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• 2004

The plasma surface modification of natural rubber vulcanizate was carried out using chlorodifluoromethane in a radio-frequency (13.56 MHz) electrodeless bell type plasma reactor. The modification was qualitatively assessed by Fourier transform infrared spectroscopy. The frictional force of the plasma-treated surface was found to decrease with the time of plasma treatment. An increase in the surface polarity, as evidenced by the decrease in contact angle of a sessile drop of water and ethylene glycol on the natural rubber vulcanizate surface, was noted with the plasma modification. In the case of similar plasma treatment of glass surface, only a reduction in the polarity was observed. The use of geometric and harmonic mean methods was found to be useful to evaluate the London dispersive and specific components of surface free energy. Irrespective of the method used for evaluation, an increasing trend in the surface free energy was noted with increasing plasma treatment time. However, the harmonic mean method yielded comparatively higher values of surface free energy than the geometric mean method. The plasma surface modification was found to vary the frictional coefficient by influencing the interfacial, hysteresis and viscous components of friction in opposing dual manners.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.470.2-470.2
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• 2014

RF-PECVD 장치에 의해 증착된 실리콘 질화막(SiNx)은 결정질 실리콘 태양전지에서 반사 방지막 효과 및 우수한 표면 패시베이션 특성을 제공하는 것으로 알려져 있다. 본 논문에서는 실리콘 질화막의 패시베이션 특성을 향상시키기 위해서 공정온도를 $400^{\circ}C$로 고정하고 공정압력, 가스비, RF (radio frequency) power를 가변하였다. 이 때의 실리콘 질화막의 굴절률 및 두께는 각각 2.0, 80 nm로 증착하여 그에 따른 특성에 대해 분석하였다. 공정 압력이 감소할수록 실리콘 질화막이 증착된 결정질 실리콘 태양전지의 유효 반송자 수명이 증가함을 보였고, 반면에 증착속도는 감소하였다. 또한 RF-power 500 W에서 실리콘 질화막이 증착된 결정질 실리콘 태양전지의 유효 반송자 수명이 상대적으로 높았으며 출력이 올라갈수록 증착속도가 증가하였다. 결과적으로 결정질 실리콘 태양전지에 증착한 실리콘 질화막은 0.8torr 공정 압력과 RF-power 500 W에서 $38.8{\mu}s$로 가장 좋은 유효 반송자 수명을 확인하였다. 위의 결과를 바탕으로 결정질 실리콘 태양전지를 제작하였고 향상된 패시베이션 특성을 갖는 실리콘 질화막의 조건을 찾기 위해서 개방전압(open circuit voltage)을 비교하였다. 공정압력 0.8 torr, RF-power 500 W에서 가장 높은 결과를 보였으며 이는 유효 반송자 수명과 유사한 결과를 나타냈다. 하지만 낮은 FF (fill factor)로 인해 변환 효율이 낮은 결과를 보였다. 태양전지 제작시 낮은 fill factor를 보인 이유와 위의 단점을 보완하기 위해 추가 실험을 수행하였으며, 개선된 fill factor를 통해 18.3% 효율의 태양전지를 제작하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.93-98
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• 2005

STSAT-2 will be launched on December 2007 by the first Korean launch vehicle KSLV-1, and its one of the main instruments is DREAM (Dual Channel Radio Frequency and Environment Atmosphere Monitoring) which detects a signal for atmosphere from the Earth by using micro-wave signal. The STSAT-2 has many units for technology demonstration such as FDSS (Fine Digital Sun Sensor) and DHST (Dual Head Star Tracker) including PPT (Pulsed Plasma Thruster) for attitude control and momentum dumping in the space. In this paper, the power budget analysis for STSAT-2 will be studied and provided for supporting the whole mission life time during the mission of its spacecraft.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.175-176
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• 2002

Our study is to search for tribological properties of diamond-like carbon (DLC) films as known as anti- wear hard thin film on various polymers. This report deals with the deposition of DLC films on various polymer substrates in vacuum by magnetron radio frequency (RF) sputtering method with using argon plasma and graphite, titanium target. The properties of friction and wear are measured using a ball-on-disk wear -testing machine. The properties of friction and wear have been remarkably improved by DLC coating. Moreover the composition of DLC films has been analyzed by using auger electron spectroscopy(AES). The wear rate of titanium-containing DLC film is lower than that of no-metal-containing DLC film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.241-241
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• 2009

For the Radio Frequency Integrated Passive Device (RFIPD) application, we have successfully developed and characterized high break-down voltage metal-insulator-metal (MIM) capacitors with 2,000 ${\AA}$ plasma-enhanced chemical vapor deposition (PECVD) silicon nitride which deposited with $SiH_4/NH_3$ gas mixing rate, working pressure, and RF power of PECVD at $250^{\circ}C$ chamber temperature. At the PECVD process condition of gas mixing rate (0.957), working pressure (0.9 Torr), and RF power (60 W), the AFM RMS value of about 2,000 ${\AA}$ silicon nitride on the bottom metal was the lowest of 0.862 nm and break-down electric field was the highest of about 8.0 MV/cm with the capacitance density of 326.5 $pF/mm^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.138-138
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• 2013

Ni-CeO2 및 Ni-MgO와 같이 Ni이 포함된 나노복합물질을 고주파 유도결합 플라즈마를 이용하여 합성하였다. 이를 위해, 먼저, 1~100 ${\mu}m$ 크기의 가상 Ni 입자와 고융점 세라믹 입자가 플라즈마 유동 내에서 겪는 열전달 과정을 수치해석을 통해 묘사하였다. 묘사 결과로부터, 완전 기화한 Ni 증기가, 채 기화하지 못하고 고체 형태로 남은 세라믹 입자 위에서 균일하게 응축된 형태를 갖는 Ni-세라믹 나노입자 합성을 예측하고, 실제 합성 실험을 25 kW 급 고주파 유도결합 플라즈마에 0.1~10 ${\mu}m$ 크기의 Ni, CeO2 및 MgO 분말을 주입하여 수행하였다. 마지막으로, 실험을 통해 합성된 Ni 계 복합나노물질에 대해, FE-SEM 및 TEM 사진 분석과 EDS 및 ICP-AES 성분 분석을 진행하고, 수치해석을 통해 예측된 결과와 비교 검토하였다.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.31-37
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• 2008

To increase output power of a He-Ne laser we propose to use the capacitive rf discharge and implement four channel structure. Most of experiments were carried out with a single laser tube from this structure to optimize the output mirror transmission, pressure and composition of the mixture. A laser tube of 2.8 mm inner diameter and 50 cm discharge length can give an output power of above 5.5 mW at 3.39 ${\mu}m$. Four such tubes in "matrix" structure let us obtain 20 mW of output. Simplified models which can be used to evaluate the behavior of an equivalent electrical circuit with laser plasma and qualitative characteristics of output power of He-Ne laser were also described.

• The Korean Journal of Ceramics
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• v.4 no.1
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• pp.9-14
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• 1998

Diamond-like carbon(DLC) films were deposited on buffer-layered ZnS substrates by radio frequency plasma enhanced chemical vapor deposition(RF-PECVD) method. Ge and GeC buffer layera were used between DLC and ZnS substrates to promote the adhesion of DLC on ZnS substrates. Ge buffer layers were sputter deposited by RF magnetron sputtering and $GeC^1$ buffer layers were deposited by same method except using acetylene reactive gas. The relatinship between film properties and deposition conditions was investigated using gas pressure, RF power and dc bias voltage as PECVD parameters. The hardness of DLC films were measured by micro Vickers hardness test and the adhesion of DLC films on buffer-layered ZnS substrates were studied by Sebastian V stud pull tester. The optical properties of DLC films on butter-layered ZnS substrates were characterized by ellipsometer and FTIR spectroscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.309-309
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• 2010

Silicon Nitride(SiN) 박막을 펄스드 플라즈마 응용화학기상법을 이용하여 저 소스전력의 $SiH_4-N_2$ 플라즈마에서 증착하였다. Duty ratio의 변화에 따른 이온에너지와 굴절률의 변화를 고찰하였다. 저이온에너지는 증착률과 강한 상관성을 보였다. 이온에너지 변수의 증착률에의 영향은 신경망 모델을 이용하여 고찰하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.42-48
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• 1999

An experimental study was performed to discover the effect of environment on the tribological behavior of Si-incorporated diamond-like carbon(Si-DLC) film slid on a steel ball. The films were deposited on Si(100) wafers from radio-frequency glow discharge of mixtures of benzene and dilute silane gases. Experiments using a ball-on-disk test-rig was performed under vacuum, dry air and ambient air conditions. It was observed that coefficient of friction was decreased as the environmental condition changes from vacuum, to dry air. It was also observed that the coefficient of friction decreased with increasing silicon concentration in the film. Chemical analyses of debris suggested that the low and stable friction coefficient is closely related to the silicon rich oxide debris and the rolling action.