• Tribology and Lubricants
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• v.16 no.3
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• pp.188-193
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• 2000

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 by a radio-frequency glow discharge of mixtures of benzene and dilute silane gases. Experiments using a ball-on-disk test-rig was performed in vacuum, dry air and ambient air conditions. It was observed that coefficient of friction decreased as the environment changed from vacuum, to dry air. Chemical analyses of debris suggested that low and stable friction is closely related to the formation of silicon-rich oxide debris and the rolling action.

• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.24-29
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• 2000

MgO thin films were deposited on soda lime glass substrates by rf magnetron sputtering using a MgO target at various oxygen flow ratios in order to probe the relationship between MgO film properties and discharge characteristics. MgO films have a tendency to form microstructures with a preferred growth orientation of (200) with increasing oxygen flo ration up to 0.1 $O_2$/(Ar+$O_2$). MgO film obtained at 0.1[$O_2$/(Ar+$O_2$)] was found to be fully stoichiometric. The stoichiometric MgO film was observed to have relatively very clean surface and grains of large size and contain almost no hydroxyl group. The AC PDP with fully stoichiometric MgO film showed lower firing and sustain voltages than those with magnesium-rich or oxygen-rich MgO films, being largely attributed to the larger grain size and the minimized hydroxyl group.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.437-437
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• 2010

DC Hollow cathode 방전은 약 100여 년 전, Paschen에 의해 실험된 이후로 광원, 스퍼터링 공정, 이온빔 소스 등 다양한 분야에 이용되어 왔다. 최근 태양전지용 마이크로 결정질 실리콘 증착 시, RF CCP의 전극에 복수의 홀 혹은 트렌치 구조를 두어 Hollow cathode 방전 효과를 이용하여 향상된 공정 속도로 공정을 진행한다. 그러나 RF-MHCD (Multi hole cathode discharge) 공정을 위한 최적 규격의 홀 기에 관한 연구는 그 중요성과 응용성에도 불구하고 깊게 이루어지지 못한 바 있다. 그러므로 저자는 Capacitively Coupled Plasma (전극 간격 : 4cm, 전극 직경 : 14cm) 장비에서 평면 전극과 10mm 깊이와 각각 3.5mm, 5mm, 7mm, 10mm 직경의 홀이 있는 4개의 전극을 이용하여 Argon RF-MHCD 방전을 관찰하여 조건 별 최적의 홀 전극 디자인을 도출하였다. 실험 조건은 64.5mTorr ~ 645mTorr압력 범위/ 1A~9A이며, 플라즈마는 전극 사이 중앙에 설치한 RF-compensated Langmuir Probe와, 전극과 전기적으로 접촉하는 1000:1 Probe 와 Voltage-Current Probe를 이용하여 측정되었다. 실험 결과 압력 조건 별로, 최적의 전자 밀도를 유도하는 전극 상 홀의 직경이 달라짐을 확인하였다.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.461-466
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• 1999

Diamond-like carbon(DLC) films were directly deposited onto germanium(Ge) witness pieces and lenses by a capacitively coupled 13.56 MHz RF glow discharge plasma with $CH_4$ gas. The characterizations of DLC films were measured using a Raman and FTIR spectrometer. The configuration of Raman and FTIR spectra had a traditional shape. The IR transmittance was measured using an IR spectrophotometer. The maximum values of the IR transmission of Ge with the DLC/Ge/DLC, DLC/Ge/BBAR (broad band antireflection), DLC/Ge, and BBAR/Ge structures are 98%, 93%, 64%, and 63.5%, respectively, which come up to the theoretical values. The uniform DLC films were obtained by a rotation of the cathode at certain conditions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.116-117
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• 2009

식각 공정변화 즉 상부 ICP 파워, 반응기 압력, 실리콘 기판 온도변화에 따른 실리콘 딥 비어 (deep via) 의 형상 변화 메커니즘을 연구하였다. 메커니즘을 연구하기 위해 $SF_6/O_2$ 플라즈마에 노출된 실리콘 기판의 공정변화에 따른 표면 온도변화를 실시간으로 측정하여 플라즈마 내 positive ions의 거동을 분석하였다. 실리콘 기판의 표면온도를 상승시키는 주된 요인은 positive ions임을 확인할 수 있었으며 이는 기판에 적용된 negative voltage로 인하여 나타난 이온포격이 그 원인임을 알 수 있었다. 상대적으로 radical은 실리콘 표면온도 상승에 큰 역할을 하지 못하였다. 기판 표면온도가 상승 할수록 실리콘 딥 비어 구조에 undercut, local bowing과 같은 측벽 식각이 활성화됨을 확인할 수 있었으며 이는 기판에 들어오는 positive ions가 측벽식각을 유도하는 것으로 해석할 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.1 no.3
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• pp.113-114
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• 1980

Lumichrome (7,8-dimethylalloxazine) exhibits two fluorescence emission maxima at 440 and 540 nm in pyridine-dioxane. These emission band maxima are attributable to radiative decays from the excited states of lumichrome and its flavin tautomer, 7,8-dimethylisoalloxazine, respectively. The growth of the latter can be followed upon excitation of the former with a 2-nanosecond light pulse generated from the nitrogen plasma discharge lamp. The excited state tautomerism results from proton transfer from N-1 to N-10 position during the lifetime of the lumichrome singlet excited state. The rate depends on the concentration of general base, pyridine, and it is an order of magnitude slower than diffusion-controlled processes.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.351-357
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• 2004

We have investigated the intensity of Cu 510.6 nm emission line in see-through hollow cathode glow discharge (st-HCGD) for the development of medical Cu vapor laser. In order to acquire the stable plasma in st-HCGD cell at high current, several factors such as current, the length and the inner diameter of cathode tube, the shape of the tube, and the range of the sputtering range were tested. An optimum condition in our st-HCGD cell was obtained at 600 V, 700 mA, 2.3 Torr of Ar gas (100 SCCM), and 40 mm of tube with 4-11-4 mm type cathode design. Also, it was indirectly observed that temperature in the cell could reach more than $1,000{\circ}C$ since Cu cathode was melt at the current more than 700 mA (melting point of Cu, $1084{\circ}C$).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.1-5
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• 2000

Recently alternating-current Plasma Display Panel(AC-PDP) is in the spotlight as a digital television and high definition television. The panel structure widely adapted in commercial AC-PDP is three electrodes surface discharge type. At present time, the luminous efficiency is around 1lm/W, it should be a key factor for the commercialization. For the high luminous efficiency, the development of panel structure is necessary. At a given panel structure, a driving method should be optimized to get a sufficient luminous efficiency. The display image of AC-PDP could be realized by the repeated light emission from the discharge. Because most of discharge power is consumed in the sustaining period, the optimization of sustaining waveform is very important for the high luminous efficiency. ADS (Address and Display period Separated) driving method is commonly used. The average driving frequency of ADS driving method is ranged by several tens kilo of [kHz], however the actual frequency of sustaining period is in range of 100[kHz] to 200[kHz]. Based on this study, when the phosphor emits the visible light, it has a decay time of few milliseconds due to the material transfer to the phosphor to emit the visible light. Consequently the luminous efficiency decreases in proportion to the driving frequency. It is found that the luminous efficiency could be significantly improved by the low frequency sustaining driving method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.861-867
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• 2001

In this paper, in order to investigate the catalytic effect of the sludge exhausted from waterworks on NO$_{x}$ removal, we measure NO removal characteristics with and without sludge pellets in BaTiO$_3$-sludge packed-bed reactor of plate-plate geometry. NO initial concentration is 50 ppm balanced with air and a gas flow rate is 5ι/min. Gas temperature is changed from 25 to 10$0^{\circ}C$ to investigate the role of sludge pellet on removing active oxygen species and NO$_2$. BaTiO$_3$pellets is filled for coronal discharge at upstream of reactor and sludge pellets is filled for catalytic effect at downstream of reactor. The volume percent of sludge pellets to BaTiO$_3$pellets is changed from 0% to 100% and AC voltage is supplied to the reactor for discharging simulated gases. In the results, when sludge pellets is put at the downstream of plasma reactor, NO removal rate is slightly increased. However, NO$_2$and $O_3$ as by-products during NO removal is significantly decreased from 51ppm without sludge pellets to 5 ppm with sludge pellets and from 50 ppm without sludge pellets to 0.004ppm with sludge pellets, respectively. Therefore, NO$_{x}$(NO+NO$_2$) removal rate is increased up to 93%. It is thought that sludge pellet maybe react with active oxygen species and NO$_2$ generated by corona discharge in surface of BaTiO$_3$pellets, the then NO$_2$O$_3$as by-products are considerably decreased. When we increase gas temperature from room temperature to 10$0^{\circ}C$, NO removal rate is decreased, while NO$_2$ concentration is independent on gas temperature. These result suggest that the removal mechanism of active oxygen species and NO$_2$in sludge pellet is not absorption, but chemical reaction. Therefore we expect that sludge pellets exhausted for waterworks could be used as catalyst for NO$_{x}$ removal with high removal rate and low by-product.oduct.

• Carbon letters
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• v.28
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• pp.31-37
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• 2018

This paper examines a simple one-step and catalyst-free method for synthesizing carbon nanoparticles from aliphatic alcohols and n-hexane with linear molecule formations by using a stable solution plasma process with a bipolar pulse and an external resistor. When the external resistor is adopted, it is observed that the current spikes are dramatically decreased, which induced production of a more stable discharge. Six aliphatic linear alcohols (methanol-hexanol) containing carbon with oxygen sources are studied as possible precursors for the massive production of carbon nanoparticles. Additional study is also carried out with the use of n-hexane containing many carbons without an oxygen source in order to enhance the formation of carbon nanoparticles and to eliminate unwanted oxygen effects. The obtained carbon nanoparticles are characterized with field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results show that with increasing carbon ratios in alcohol content, the synthesis rate of carbon nanoparticles is increased, whereas the size of the carbon nanoparticles is decreased. Moreover, the degree of graphitization of the carbon nanoparticles synthesized from 1-hexanol and n-hexane with a high carbon (C)/oxygen (O) ratio and low or no oxygen is observed to be greater than that of the carbon nanoparticles synthesized from the corresponding materials with a low C/O ratio.