• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.719-720
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• 2004

A multi-megawatt long pulse ion source (LPIS) of neutral beam injector was developed for the KSTAR. Beam extraction experiments of the LPIS were carried out at the neutral beam test stand (NBTS). Design requirements for the ion source were 120 kV/65 A deuterium beam and a 300 s pulse length. A maximum ion density of $9.1310^{11}$ $cm^{-3}$ was measured by using electric probes, and an optimum arc efficiency of 0.46 A/kW was estimated with ion saturation current of the probes, arc power, and total beam area. An arcing problem, caused by the structural defect of decelerating grid supporter, in the third gap was solved by the blocking of backstream ion particles, originated from the plasma in the neutralizer duct, through the unnecessary spaces on the side of grid supporter. A maximum drain power of 1.5 MW (i.e. 70 kV/21 A) with hydrogen was measured for a pulse duration of 0.5 s. Optimum beam perveance was ranged from 0.75 to 0.85. An improved design of accelerator for the effective control of beam particle trajectory should provide higher beam perveance.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.109-109
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• 2000

Recently, carbon nanotube has been investigating for field emission display ( (FED) applications due to its high electron emission at relatively low electric field. However, the growing of carbon nanotube generally requires relatively high temperature processing such as arc-discharge (5,000 ~ $20,000^{\circ}C$) and laser evaporation (4,000 ~ $5,000^{\circ}C$) methods. In this presentation, low temperature growing of carbon nanotube by plasma enhanced chemical vapor deposition (PECVD) using nickel catalyst which is compatible to conventional FED processing temperature will be described. Carbon n notubes with average length of 100 run and diameter of 2 ~ $3\mu$ill were successfully grown on silicon substrate with native oxide layer at $550^{\circ}C$using nickel catalyst. The morphology and microstructure of carbon nanotube was highly depended on the processing temperature and nickel layer thickness. No significant carbon nanotube growing was observed with samples deposited on silicon substrates without native oxide layer. This is believed due to the formation of nickel-silicide and this deteriorated the catalytic role of nickel. The formation of nickel-silicide was confirmed by x-ray analysis. The role of native oxide layer and processing parameter dependence on microstructure of low temperature grown carbon nanotube, characterized by SEM, TEM XRD and R없nan spectroscopy, will be presented.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권12호
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• pp.673-678
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• 2000

The dielectric barrier discharge(DBD) is a common method to create a nonthermal plasma in which electrical energy is used to create electrons with a high average kinetic energy. The unique aspect of dielectric barrier discharges is the large array of short lifetime(10ns) silent discharges created over the surface of the dielectric. A silent discharge is generated when the applied voltage exceeds the breakdown voltage of the carrier gas creating a conduction path between the applied electrode and grounded electrode. As charge accumulates on the dielectric, the electric field is reduced below the breakdown field of the carrier gas and the silent discharge self terminates preventing the DBD cell from producing a thermal arc. In fact, the most significant application of dielectric barrier discharges is to generate ozone for contaminated water treatment. Therefore, experiments were perfomed at 1∼2[bar] pressure using a coaxial geometry single dielectric barrier discharge for ozone concentrations and energy densities. The main result show that the concentration and efficiency of ozone are influenced by gas nature, gas quantity, gas pressure, supplied voltage and frequency.

• 상하수도학회지
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• 제20권1호
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• pp.79-85
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• 2006

Innovated technique to oxidize pollutants has been developed. The technique for this study uses plasma discharge in 2-phase (Air-Water) and is called Discharged Water Generating (DWG) system. It produces electric arc which generates not only the physical decomposing power against the pollutants but also oxidants to sterilize pollutants depending on the inlet gas species. These physical and chemical products play an important role in COD decrease and biodegradability enhancement. The enhancement of biodegradability for the refractory organic substances in aqueous solution was estimated in this study. Argon discharge reduced NBDCOD of EDTA from 58.7mg/L to 38.8mg/L, but oxygen discharge and ozonation reduced it to 37.74mg/L and 38.73mg/L respectively. Furthermore, Argon discharge changed 1181mg/L of NBDCOD of dye effluent into 606mg/L but oxygen discharge and ozonation changed it into 888mg/L and 790mg/L respectively.

• 자원리싸이클링
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• 제6권4호
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• pp.3-10
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• 1997

Electric are furnace dust (EAF dust) generated in steel production based on scrap melting is contained Zn and Fe about 25 and 30 percent by weight, respectively. From a metallurgical point of view, the dust could be regarded as a raw material for Zn and Fe source. To recover the Zn in the metal from EAF dust, many system are proposed such as Arc Plasma Furmace and Pb splasher method. In this study, to recover high purity Zn from Pb splasing alloy, Zn distillation is carried out at the temperature of 1123, 1173, 1223, 1273 K, the gas flow rate of 2.5, 5.0, 8.0 Ni/min and the distilling time of 10, 30, 60, 90 minutes. The main results obtained from this study are as follows:(1) The amount of evaporated Zn and its evaporating rate increased with increasing temperature, but purity of Zn decreased with increasing temperature. Optimum temperature range was found out to be between 1173∼1223K. (2) The amount of evaporated Zn and evaporation rate increased with increasing gas flow rate at a given temperature and distillation time. Gas flow rate has more influence over the amount of evaporated Zn and evaporation rate with increasing temperature.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.362-370
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• 2006

The purpose of this paper was to investigate the reforming characteristics and optimum operating condition of the plasmatron assisted $CH_4$ reforming reaction for the hydrogen-rich gas production. Also, in order to increase the hydrogen production and the methane conversion rate, parametric screening studies were conducted, in which there were the variations of the $CH_4$ flow ratio, $CO_2$ flow ratio, vapor flow ratio, mixing flow ratio and catalyst addition in reactor. High temperature plasma flame was generated by air and arc discharge. The air flow rate and input electric power were fixed 5.1 l/min and 6.4 kW, respectively. When the $CH_4$ flow ratio was 38.5%, the production of hydrogen was maximized and optimal methane conversion rate was 99.2%. Under these optimal conditions, the following synthesis gas concentrations were determined: $H_2$, 45.4%; CO, 6.9%; $CO_2$, 1.5%; and $C_2H_2$, 1.1%. The $H_2/CO$ ratio was 6.6, hydrogen yield was 78.8% and energy conversion rate was 63.6%.

• 한국표면공학회지
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• 제36권1호
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• pp.27-33
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• 2003

Pulsed magnetron sputtering of graphite target was employed for deposition of diamond-like carbon (DLC) films. Time-resolved probe measurements of magnetron discharge plasma have been performed. It was shown that the pulsed magnetron discharge plasma density ($∼10^{17}$ $m^{-3}$ ) is close to that of vacuum arc cathode sputtering of graphite. Raman spectroscopy was sed to examine DLC films produced at low ( $U_{sub}$ / < 1 kV) pulsed bias voltages applied to the substrate. It has been shown that maximum content of diamond-like carbon in the coating (50-60%) is achieved at energy per deposited carbon atom of $E_{c}$ =100 eV. In spite of rather high percentage of $sp^3$-bonded carbon atoms and good scratch-resistance, the films showed poor adhesion because of absence of ion mixing between the film and the substrates. Electric breakdowns occurring during the deposition of the insulating DLC film also thought to decrease its adhesion.

• 공업화학
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• 제20권4호
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• pp.423-429
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• 2009

본 연구의 목적은 바이오가스를 이용하여 고농도 수소 생산과 CO 제거가 가능한 글라이딩아크 플라즈마 개질 시스템의 개발이다. 이를 위하여 수성가스 전이반응기는 수증기 주입량 변화,촉매층 온도 변화에 대하여, 선택적 산화반응기는 촉매층 온도변화, 공기주입량에 대하여 실험을 진행하였다. 기준조건은 S/C 비 3, 촉매층 온도 $700^{\circ}C$, 전체가스량 16 L/min, 입력전력 2.4 kW, 바이오가스 구성비($CH_4$ : $CO_2$ ) 6 : 4이다. 이때의 실험결과는 HTS의 최적조건은 S/C비 3, 반응온도 $500^{\circ}C$, LTS의 최적조건은 S/C 비 2.9, 반응온도 $300^{\circ}C$이다. 또한 PROX I단의 최적조건은 각각 공기유입량 300 mL/min, $190^{\circ}C$, PROX II단의 최적조건은 공기유입량 200 mL/min, $190^{\circ}C$을 나타내었다. 반응기를 모두 지난 후의 합성가스는 $H_2$ 수율 55%, $CH_4$ 전환율 97%, $CO_2$ 전환율 97%, CO 선택도는 0%로 바이오가스를 개질하여 생성된 합성가스는 높은 수율을 나타내며, CO 선택도는 0%를 나타내었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.16-16
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• 2012

Mg and its alloys have been of great interest because of their low density of 1.7, 30% lighter than Al, but their wide applications have been limited because of their poor resistances against corrosion and/or abrasion. Corrosion resistance of Mg alloys can be improved by formation of anodic films using anodic oxidation method in aqueous electrolytes. Plasma electrolytic oxidation (PEO) is one of anodic oxidation methods by which hard anodic films can be formed as a result of micro-arc generation under high electric field. PEO method utilize not only substrate elements but also chemical components in electrolytes to form anodic films on Mg alloys. PEO films formed on AM50 magnesium alloy in an acidic fluozirconate electrolyte were observed to consist of mainly $ZrO_2$ and $MgF_2$. Liu et al reported that PEO coating on AM30 Mg alloy consists of $MgF_2$-rich outer porous layer and an MgO-rich dense inner layer. PEO films prepared on ACM522 Mg die-casting alloy in an aqueous phosphate solution were also reported to be composed of monoclinic $Mg_3(PO_4)_2$. $CeO_2$-incorporated PEO coatings were also reported to be formed on AZ31 Mg alloys in $CeO_2$ particle-containing $Na_2SiO_3$-based electrolytes. Magnesium tin hydroxide ($MgSn(OH)_6$) was also produced on AZ91D alloy by PEO process in stannate-containing electrolyte. Effects of $OH^-$, $F^-$, $PO{_4}^{3-}$ and $SiO{_3}^{2-}$ ions and alloying elements of Al and Sn on the formation of PEO films on pure Mg and Mg alloys and their protective properties against corrosion have been investigated in this work. $PO{_4}^{3-}$, $F^-$ and $SiO{_3}^{2-}$ ions were observed to contribute to the formation of PEO films but $OH^-$ ions were found to break down the surface films under high electric field. The effect of pulse current on the formation of PEO films will be also reported.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.383-383
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• 2009

Silicon is commercially prepared by the reaction of high-purity silica with wood, charcoal, and coal, in an electric arc furnace using carbon electrodes, so called the metallurgical refining process, which produces ~98% pure Si (MG-Si). This can be further purified to solar grade silicon (SoG-Si) by various techniques. The most problematic impurity elements are B and P because of their high segregation coefficients. In this study, we explored the possibility of the using Cat-CVD for Si purification. The existing hot-wire CVD was modified to accommodate the catalyzer and the heating source. Mo boat (1.5 cm ${\times}$ 1 cm ${\times}$ 0.2 cm) was used as a heating source. Commercially available Si was purchased from Nilaco corporation (~99% pure). This powder was kept in the Mo-boat and heated to the purification temperature. In addition to the purification by cat-CVD technique, other methods such as thermal CVD, plasma enhanced CVD, vacuum annealing was also tried. It is found that the impurities are reduced to a great extent when treated with cat-CVD method.