• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.88-91
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• 2004

In order to improve ozone generation, we experimentally investigated the silent discharge plasma and ozone generation characteristics of a multi-discharge type ozonizer. Ozone in a multi-discharge type ozonizer is generated by superposition of a silent discharge plasma, which is simultaneously generated in separated discharge spaces. A multi-discharge type ozonizer is composed of three different kinds of superposed silent discharge type ozonizers, depending on the method of applying power to each electrode. We observed that the discharge period of the current pulse for a multi-discharge type ozonizer can be longer than that of silent discharge type ozonizer with two electrodes and one gap.Hence, ozone generation is improved up to 17185 ppm and 783 g/kwh for the superposed silent discharge type ozonizer for which an AC high voltages with a 180 phase difference were applied to the internal electrode and the external electrode, respectively, with the central electrode being ground

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2251-2260
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• 2021

The motion control of the divertor maintenance system of the China Fusion Engineering Test Reactor (CFETR) was studied in this paper, in which CFETR Multi-Functional Maintenance Platform (MFMP) was simplified as a parallel robot for the convenience of theoretical analysis. In order to design the motion controller of parallel robot, the kinematics analysis of parallel robot was carried out. After that, the dynamic modeling of the hydraulic system was built. As the large variation of heavy payload on MFMP and highly nonlinearity of the system, A Fuzzy-PID controller was built for self-tuning PID controller parameters by using Fuzzy system to achieve better performance. In order to test the feasibility of the Fuzzy-PID controller, the simulation model of the system was built in Simulink. The results have showed that Fuzzy-PID controller can significantly reduce the angular error of the moving platform and provide the stable motion for transferring the divertor.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.57-62
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• 2022

The plasma resistance of multi-component glasses containing La, Gd, Ti, Zn, Y, Zr, Nb, and Ta was analyzed in this study. The plasma etching was performed via inductively coupled plasma-reactive ion etching (ICP-RIE) using CF₄/O₂/Ar mixed gas. After the reaction, the glass with a low fluoride sublimation temperature and high content of P, Si, and Ti elements showed a high etching rate. On the other hand, the glass containing a high fluoride sublimation temperature component such as Ca, La, Gd, Y, and Zr exhibited high plasma resistance because the etch rate was lower than that of sapphire. Glass with low plasma resistance increased surface roughness after etching or nanoholes were formed on the surface, but glass with high plasma resistance showed little change in surface microstructure. Thus, the results of this study demonstrate the potential for the development of plasma-resistant glasses (PRGs) with other compositions besides alumino-silicate glasses, which are conventionally referred to as plasma-resistant glasses.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.426-430
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• 2000

We have studied the field emission characteristics of multi-layered diamond-like-carbon (DLC) films deposited by vertical electrodes type plasma enhanced chemical vapor deposition with CH$_4$ and H$_2$ mixture. We deposited a thin layer of DLC on the p$^{+}$-Si substrate and then turned off plasma before another deposition of a new DLC layer. The thickness and the number of DLC layers are varied. The emission characteristics of multi-layered DLC films were compared with conventional one. The multi-layered DLC film shows higher emission current than conventional one.e.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.290-296
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• 2011

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as a resistive gas sensors for the $H_2$ gas detection. Sensor films were fabricated by the air spray method using the multi-walled CNTs dispersion solution on the glass substrates cured with plasma and nitrocellulose. Sensors were characterized by the resistance measurements in the self-fabricated oven in order to find the optimum detection properties for the hydrogen gas molecular. The sensitivity and the linearity of the MWVNT sensors using the glass substrate cured with plasma for the $H_2$ gas concentration of 0.06~0.6 ppm are 0.013~0.097%/sec and 0.131~0.959%FS, respectively. The MWCNT film was excellent in the response for the hydrogen gas moleculars and its reaction speed was very fast, which could be using as hydrogen gas sensor. The resistance of the fabricated sensors decreases when the sensors are exposed to $H_2$ gas.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1412-1416
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• 2014

We report thin-film organic moisture barriers based on polystyrene(PS) laminates deposition by PECVD for an encapsulation of OLEDs. The organic polystyrene thin-film has the benzene ring structure and high hydrophobic characteristics and it was polymerized by PECVD in dry process. Life time properties of Ca test were obtained 32 minutes at the RF 100W process conditions. From the AFM test, the roughness of multi-layer thin-film was more excellent rather than that of a single-layer thin-film. In addition, 5 layers of the multi-layer film properties were obtained 45 minutes. So that the optical and electrical properties were not affected with these plasma polymerized organic thin-film encapsulation. For life time improvement, the inorganic $Al_2O_3$ thin-film were deposited 5nm using ALD atomic layer deposition. The WVTR(Water Vaper Transmission Rate) value of hybrid thin-film encapsulation in the optimum process conditions was resulted by less than $10-3g/m^2/day$. From the results of experiment, plasma polymerized hybrid encapsulation was suggested as the flexible display applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.508-508
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• 2012

CST microwave studio is used to simulate the plasma profile of the 450mm CCP source. Standing wave effect becomes important at the high frequency as the electrode radius increases. To solve plasma non-uniformity problem, we designed multi electrode chamber to decreasing standing wave effect. Simulation showed the ratio of input power of each electrode is related with electric field strength. The multi electrode was constructed and measured by 2D probe arrays using floating harmonic method. Uniformity of 450 mm CCP was changed by the ratio of input power of each electrode. We described this dependence with circuit model.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.24-28
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• 1997

Diamond deposition by muti-cathode DC PACVD has been investigated. Five cathodes were independently connected to their own DC power supplies. The voltage and current of each cathods were varied up to 700 V and 3.5 A, respectively. The plasma formation and the diamond deposition behaviour on a substrate of 3 inch in diameter were investigated by optical emission spectroscopy, SEM and Raman spectroscopy. The plasma formed by five cathodes was non-uniform, which was depended on the geometry of cathods array. The growth rate and the quality of diamond film were closely related to the spatial distribution of the plasma.

• Journal of the Korean Vacuum Society
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• v.19 no.5
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• pp.331-340
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• 2010

3D fluid based numerical modelling is done for a VHF multi hollow cathode array plasma enhanced chemical vapor deposition system. In order to understand the fundamental characteristics of it, Ar plasma is analyzed with a condition of 40 MHz, 100 Vrf and 1 Torr. For hole array of 6 mm diameter and 20 mm inter-hole distance, plasma is well confined within the hole at an electrode gap of 10 mm. The peak plasma density was $5{\times}10^{11}#/cm^3$ at the center of the hole. When the substrate was assumed at ground potential, electron temperature showed a peak at the vicinity of the grounded walls including the substrate and chamber walls. The reaction rate of metastable based two step ionization was 10 times higher than the direct electron impact ionization at this condition. For $H_2$, the spatial localization of discharge is harder to get than Ar due to various pathways of electron impact reactions other than ionization.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.99-100
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• 2007

유도결합 플라즈마(ICP)를 이용한 CVD 장치에서 플라즈마를 발생시키기 위한 안테나의 구조는 매우 중요하다. 전자 온도와 전자 밀도에 직접적인 영향을 주게 되며, 뿐만 아니라 증착 물질의 두께 균일도에 결정적인 역할을 하게 된다. 본 연구에서는 플라즈마 특성 균일도 최적화를 위하여 2turn 직렬, 병렬, 혼합의 ICP 안테나의 구조에 대하여 플라즈마 특성 및 $SiO_2$ CVD 증착 특성을 계산하였다.