• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1533-1535
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• 1994

The Monte-Carlo simulation was used to define the physical mechanisms of the initiation phase of pseudo-spark discharge. The pseudo-spark discharge employing the hollow cathode geometry is accompanied by very fast current rising and intense charged particle beams. In this model, time-dependent continuity equation for the electrons and ions were solved consistently with Poisson's equation for the electric field in a two-dimensional, sysmmetrically cylinderical geometry. From the simulation, a sequence of physical mechanisms that cause the rapid current rise associated with the onset of pseudo-spark discharge mode were identified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.7
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• pp.571-580
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• 1998

The numerical model that can describe the ignition of pseudospark discharge using hybrid fluid-particle(Monte Carlo )method has been developed. This model consists of the fluid expression for transport of electrons and ions and Poisson's equation in the electric field. The fluid equation determines the spatiotemporal dependence of charged particle densities and the ionization source term is computed using the Monte carlo method. This model has been used to study the evolution of a discharge in Argon at 0.5 torr, with an applied voltage if 1kV. The evolution process of the discharge has been divided into four phases along the potential distribution : (1) Townsend discharge, (2) plasma formation, (3) onset of hollow cathode effect, (4) plasma expansion. From the numerical results, the physical mechanisms that lead to the rapid rise in current associated with the onset of pseudospark could be identified.

• Journal of the Korean Chemical Society
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• v.41 no.2
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• pp.113-116
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• 1997

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.11a
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• pp.57-57
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• 1998

최근 건식도금 분야에 있어서 경제성의 확보를 위해 고속 증착에 관한 연구가 활발히 진행 중에 있다. 이러한 고속 증착의 방법으로서는 high current arc, laser arc, hollow cathode discharge 및 magnetron sputtering법 등이 대두되고 있다. 특히 이중 magnetron sputtering 법은 고밀도의 박막을 고속으로 증착활 수 있는 장점으로 인해 고속 증착의 효과적인 방법으로 크게 대두되고 있다. 이러한 magnetron sputtering 법을 이용한 고속 증착에 관한 연구는 Cu, Ag와 같은 순수 금속 박막의 경우 $1~3\mu\textrm{m}/min$의 증착율까지 확보한 연구결과가 이미 발표되 고 있다. 그러나 이러한 고속 증착에 관한 연구들은 순금속 박막의 증착에 한정되어 있고 화합물 박막의 고속 증착에 관한 연구결과는 거의 전무한 결과이다. 따라서 본 연구에서는 magnetron sputtering 법을 이용하여 Ti계와 Cr계의 화합물 박막을 고속으로 증착하였다. 포한 박막의 증착율 및 특성 분석을 위혜 a-step, XRD 및 SEM을 이용하였다. 본 연구의 결과 $0.25~0.38\mu\textrm{m}/min$. 증착율을 확보하였으며 XRD 분석을 통하여 화합물 박막의 합성여부를 확인하였고, 박막의 미소 경도값도 2300~2500HK의 값을 얻었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.2-253.2
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• 2014

Micro hollow cathode discharges (MHCDs) are high-pressure, non-equilibrium discharges. Those MHCDs are useful to produce an excimer radiation. A major advantage of excimer sources is their high internal efficiency which may reach values up to 40% when operated under optimum conditions. To produce strong excimer radiation, the optimisation of the discharge conditions however needs a detailed knowledge of the properties of the discharge plasma itself. The electron density and temperature influence the excitation as well as plasma chemistry reactions and the gas temperature plays a major role as a significant energy loss process limiting efficiency of excimer radiation. Most of the recent spectroscopic investigations are focusing on the ultraviolet or vacuum ultraviolet range for direct detection of the excimer. In our experiments we have concentrated on investigating the micro hollow cathodes from the near UV to the near infrared (300~850 nm) to measure the basic plasma parameters using standard plasma diagnostic techniques such as stark broadening for electron density and the relative line intensity method for electron temperature. Finally, the neutral gas temperature was measured by means of the vibrational rotational structures of the second positive system of nitrogen.

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.14-22
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• 2006

the basic model of chemical reactor using glow discharge, we used cathode discharge cell with vacant cavity in the middle. Currently glow discharge is widely studied as a radiation source or atomization device in atomic spectroscopy and remarkable technological achievements are made through the graft with other analysis devices such as microanalysis and steel analysis.1 Additionally, as the characteristics of basic glow discharge and radiation have been reviewed many times, those results could be used in this experiment.2-3 In 1993, an article regarding the treatment of poisonous gas in the air using low temperature plasma was published. According to this article, if DC Glow Discharge is used under continuous atmospheric flow, poisonous gases such as SO2 and NO can be removed.4 Based on those findings, we designed highly efficient reactor where stable air plasma is composed and all air flow pass the negative glow area passing through the tube. It was observed that the cathode tube type glow discharge developed in this study would be economical, easy to use and could be used as radiation source as well.

• Tribology and Lubricants
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• v.20 no.5
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• pp.237-244
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• 2004

Micro/nano tribological characteristics of PTFE coating films were experimentally studied. PTFE (polytetrafluoroethylene) modified polyethylene and low molecular weight PTFE were used as a coating materials. These films were deposited on Si-wafer (100) by IBAD (ion beam assisted deposition) method. The Ar ion beam sputtering was performed to change the surface topography of films using a hollow cathode ion gun under different Ar ion dose conditions in a vacuum chamber. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribotester, SPM (scanning probe microscope), contact anglemeter and profilometer, respectively. The durability of the films were measured with macro tribotester. Results showed that the PTFE coating surfaces were converted to hydrophobic. The water contact angle of coated surfaces and surface roughness increased with the coating thickness. Adhesion and friction in micro and nano scale were governed by magnitude of normal load in soft material such as PTFE films. As the increase of sputtering time on low molecular weight PTFE films, the surface roughness was increased and nano adhesion and friction were decreased. The nano tribological characteristics of surfaces are mainly improved by chemical modification such as PTFE coating and given a synergy effect by the physical modification such as topographic modification.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.25-33
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• 2002

Effect of surface topography on the water wetting nature and micro/nano tribological characteristics of Si-wafer and PTFE was experimentally studied. The ion beam treatment was performed with a hollow cathode ion gun in different argon don dose conditions in a vacuum chamber to change the surface topography, Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribo tester, SPM (scanning prove microscope), contact anglemeter and profilometer, respectively. Results showed that surface roughness increased with the argon ion dose. The water wetting angle of tile ion beam treated samples also increased with the ion dose. Results also showed that micro-adhesion and micro-friction depend on the wetting characteristics of the PTFE samples. However, nano-triboloSical characteristics showed little dependence on the wetting angles. The water wetting characteristics of modified PTFE samples were discussed in terms of the surface topographic characteristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.19-26
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• 2006

The ccrf-discharge has in comparison with the hollow-cathode discharge and DC-discharge some advantages: Simple design of the tube and homogeneous plasma. The ccrf-discharge was researched with the goal, to use on the excitation of the gas laser. In this work a rf-exciting system was planned and developed. With it a homogeneous discharge was produced in the cw operation. To supply the rf-power with the frequency 13.56[MHz] effectively in the discharge, laser tube were used with inner diameter of 5[mm] and the specially developed rf-electrodes. A matching circuit was composed also. Thereby the impedance of the discharge tube was adjusted to the 50[$\Omega$] output resistance of the rf-source.

• KSTLE International Journal
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• v.3 no.1
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• pp.12-16
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• 2002

Micro/nano tribological and water wetting characteristics of ion beam treated PTFE (polytetrafluoroethylene) surfaces were experimentally studied. The ion beam treatment was performed with a hollow cathode ion gun at different argon ion dose conditions in a vacuum chamber to modify the topography of PTFE surface. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribe tester, SPM (scanning probe microscope), contact anglemeter and profilometer, respectively. Results showed that surface roughness increased with the argon ion dose. Water wetting angle of the ion beam treated samples increased with the ion dose, so the surface shows an ultra-hydrophobic nature. Micro-adhesion and micro-friction depend on the wetting characteristics of the PTFE samples. However, nano-tribological characteristics showed different results. The scale effect of surface topography on tribological characteristics was discussed. Also, the water wetting characteristics of modified PTFE samples were discussed in terms of the surface topographic characteristics.