• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.459-466
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• 2012

In order to improved treatment performance of dielectric barrier discharge (DBD) plasma, plasm + UV process and gas-liquid mixing method has been investigated. This study investigated the degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the generation of OH radical). The basic DBD plasma reactor of this study consisted of a plasma reactor (consist of quartz dielectric tube, titanium discharge (inner) and ground (outer) electrode), air and power supply system. Improvement of plasma reactor was done by the combined basic plasma reactor with the UV process, adapt of gas-liquid mixer. The effect of UV power of plasma + UV process (0~10 W), gas-liquid mixing existence and type of mixer, air flow rate (1~6 L/min), range of diffuser pore size (16~$160{\mu}m$), water circulation rate (2.8~9.4 L/min) and UV power of improved plasma + UV process (0~10 W) were evaluated. The experimental results showed that RNO degradation of optimum plasma + UV process was 7.36% higher than that of the basic plasma reactor. It was observed that the RNO decomposition of gas-liquid mixing method was higher than that of the plasma + UV process. Performance for RNO degradation with gas-liquid mixing method lie in: gas-liquid mixing type > pump type > basic reactor. RNO degradation of improved reactor which is adapted gas-liquid mixer of diffuser type showed increase of 17.42% removal efficiency. The optimum air flow rate, range of diffuser pore size and water circulation rate for the RNO degradation at improved reactor system were 4 L/min, 40~$100{\mu}m$ and 6.9 L/min, respectively. Synergistic effect of gas-liquid mixing plasma + UV process was found to be insignificant.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.394-401
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• 2005

A nonthermal plasma-assisted fuel reformer was developed and the effects of operating variables on the performance of this reformer were studied. The $H_2$-rich reformed gas from the reformer was injected into a diesel engine under an idle condition and the effects of the amount of injected gas on the NO and soot reduction were investigated. It was found that with increasing electric power consumption, the degree of facility of ignition of the reforming reaction in the reformer could be enhanced. The performance of the reformer including $H_2$ concentration, $H_2$ recovery, and energy conversion was affected only by the O/C mole ratio. This was because the equilibrium reaction temperature was governed by the O/C mole ratio. With increasing O/C mole ratio, the $H_2$ recovery and energy conversion passed through the maximum values of 33.4% and 66%, respectively, at an O/C mole ratio between 1.2 and 1.5. The reason why the $H_2$ recovery and energy conversion increased with increasing O/C mole ratio when the O/C mole ratio was lower than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction occurred more enough with increasing O/C mole ratio in this low O/C mole ratio range and accordingly the reaction temperature increased. Whereas the reason why the $H_2$ recovery and energy conversion decreased with increasing O/C mole ratio when the O/C mole ratio was higher than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction was further advanced and the $H_2$ recovery and energy conversion decreased. As the weight ratio of reformed diesel to total diesel which entered the diesel engine was increased to $18.2{\sim}23.5%$, NO and soot reduction efficiencies increased and reached as values high as 68.5% and 23.5%, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.772-777
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• 2003

선박이 배출하는 안정수(ballast water)는 외부로부터 유해 생물들이 유입되어 전파해 오는 주요경로로써 해양환경의 매우 중요하고 위험한 일종의 하나이지만, 이에 대한 효과적인 처리방법은 아직까지도 개발되지 못하였다. 그러나 최근 강 전리방전을 이용하여 고 밀집 산소와 물분자를 고농도 수산자유기(OH: hydroxyl radical)로 전리, 활성입자를 발생시켜 신속히 확산시키면 넓은 범위에서 비교적 낮은 농도로 유해성 침입 생물을 잔류물 없이 저렴한 비용으로 살균제나 촉매제의 사용 없이 소멸시켜 처리하는 효과적인 새로운 녹색방법을 제안하였다. 또한, 수산기는 강 산화제로써(산화환원 전위는 2.80 eV), 적조생물을 신속, 효과적으로 사멸시켜 잔유물과 오염물 발생 없이 이상적으로 해양적조현상을 처리할 수 있는 활성물질이다. 고출력 강 전리장치를 활용하면 수산기 활성제의 발생 농도를 Sr104 이상으로 얻을 수 있으므로, 해양적조처리에 요구되는 문턱 값 농도(~l$\times$$10^{-6}$)를 충족시킬 수 있으며, 이 경우 적조생물 소멸처리시간은 불과 10 sec 내외이므로 선박 안정수 처리문제와 함께 적조발생의 난문제를 해양동력학적으로 동시에 해결할 수 있는 효과적인 기술이다. 실험결과로부터 시간당 1 k톤의 활성물질을 발생하는 수산기활성제 제조장치의 경우, 약 4$\times$$10^2$ $\textrm{km}^2$/h의 적조해면을 처리할 수 있으며, 그 비용은 약 US$l,000 정도에 상당하므로, 적조에 따른 경제손실과는 비교될 수 없는 저렴하고 효과적인 방법이다. 활성물질의 생성시간과 가공시간은 불과 수십 $\mu\textrm{s}$ 및 수 sec 에 불과하므로, 1 kton/h 용량의 수산기활성제 제조장치의 환산소비동력은 약 200 kW이고, 장치의 체적은 10~30 ㎥의 공간으로 충분하므로, 소형선박으로 상당면적의 적조피해를 효과적으로 해결할 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.337-337
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• 2014

투명 전도성 산화물(transparent conductive oxide: TCO) 박막은 높은 투과율과 낮은 비저항 덕분에 LCD (liquid crystal display), PDP (plasma display panel), OLED (organic light emitting display) 등 평판 디스플레이에 널리 사용되고 있다. 현재 양산되고 있는 ITO (indium tin oxide)는 90% 이상의 높은 투과율과 우수한 전도성으로 인해 TCO 박막 가운데서 디스플레이 산업에서 가장 널리 쓰이고 있다. 그런데, ITO의 인듐산화물에 의한 간질성 폐렴(interstitial pneumonia)의 유발 위험이 있다든가, 인듐의 매장량이 적어 원자재 가격이 비싼 단점도 가지고 있다. 이에 최근 ITO를 대체할 수 있는 TCO물질로 많은 연구가 이루어지고 있는데, 특히 AZO (aluminum-doped zinc oxide)는 그 중 대표적인 대체물질로서 독성이 없고 가격도 저렴하여 많은 관심이 증폭되고 있다. 현재 AZO는 sol-gel 방법이나 CVD (chemical vapor deposition) 또는 스퍼터링 방법 등으로 증착되고 있다. 본 연구에서는 두 개의 이종타겟(hetero target)을 장착한 대향 타겟 스퍼터링(facing target sputtering: FTS) 장치를 사용하여 AZO 박막을 제작한다. 기존의 여러 증착법과 달리, FTS 장치는 두 타겟 사이에 형성되는 플라즈마 내의 ${\gamma}$-전자를 구속하게 되며, 낮은 가스 압력에서 고밀도 플라즈마가 생성되어 빠른 증착 속도와 안정적인 방전을 유지한 상태에서 박막을 증착할 수가 있다. 또한 기판과 플라즈마가 이격되어 있어 높은 에너지를 갖는 입자들의 기판 충돌을 억제할 수 있는 장점들을 갖는다. 이종 타겟인 ZnO와 Al2O3를 사용하고 각 타겟에 인가되는 파워 변화를 통해 AZO 박막 내 Al2O3의 성분비를 조절하였다. ZnO 타겟의 증착 파워를 100 W로 고정할 경우, Al2O3 타겟의 증착 파워가 (50~90) W으로 실험을 하였으며, Al2O3 타겟의 증착 파워가 70 W일 때 AZO 박막의 Al2O3 성분비는 2.02 wt.%이며 박막의 비저항 값은 $5{\times}10^{-4}{\Omega}{\cdot}cm$로 최소값을 보였다. 이러한 비저항의 변화는 파워에 따른 AZO 박막의 캐리어 이동도(Hall mobility)와 캐리어의 농도(Carrier Concentration)의 변화와 밀접한 관계가 있음을 보여주며, 특히 AZO 박막의 캐리어 농도와 캐리어 이동도는 AZO 박막을 형성하고 있는 결정립의 크기에 의존하는 것이 X-선 회절 패턴과 SEM으로부터 확인되었다. 특히, 본 연구에서는 두 개의 이종 타겟(hetero target) Al2O3와 ZnO를 장착하고 각각의 파워를 변화시켜 도핑 량을 조절할 수는 대향 타겟 스퍼터링(FTS: facing-target sputtering) 방법을 이용하여 제작된 AZO 박막에 대해 전기적, 광학적 및 구조적 특성을 분석하고 ITO의 대체물로서의 가능성을 검토하고자 한다.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.495-500
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• 2008

The amount of vapor mercury for the generation of glow discharge plasma has been calculated in a fine tube fluorescent lamp having a mixed gas of Ne+Ar including a mercury. When the ionization of atom is considered by the collision between neutral atoms (Ne, Ar, Hg) and electrons of energy $kT_e{\sim}1\;eV$, the density of vapor mercury atom has been obtained as $n(Hg){\sim}3.43{\times}10^{22}m^{-3}$ for the plasma density $n_o{\sim}10^{17}m^{-3}$. In the fluorescent lamps of out diameter 4 mm used for $32{\sim}42$-inch LCD-TVs having a mixture gas of Ne(95%)+Ar(5%) with the pressure of 50 Torr, the quantity of vapor mercury for the glow discharge has been caculated as 0.02{\sim}0.08\;mg$.

• Analytical Science and Technology
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• v.9 no.1
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• pp.26-34
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• 1996

A method to determine the trace amount of Se and Bi in the scalp hair using the hydride generation inductively coupled plasma atomic emmission spectrometry was studied. The optimum operation conditions of ICP for hydride generation are 0.6~0.8L/min for the carrier gas flow rate, and 6mm above the induction coil for the observation height. Hydrochloric acid concentrations for the optimum hydride generation conditions were greater than 1.5M when 2.5% $NaBH_4$ and NaOH were used, and greater than 0.5M when 2.5% $NaBH_4$ and 0.1% NaOH were used. Severe interference effects are observed from transition metals such as Cu and Ni, and they could be circumvented by the coprecipitation with lanthanum hydroxide.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.540-543
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• 2010

In this study, we made low temperature plasma reactor in order to treat safely $NO_x$ which included in the gas. We investigated experimently and inspected efficiency characteristics of equipment about flow rate of reactant material and discharge input power which supplied into reactor. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and supplied the speed of a current to 1~4 l/min. When the amount of flow increased, reduction rate of NO was low. Also when discharge input power was high, decomposition of NO was easy. Also the longer delay time of reaction material and the higher discharge input power was, the higher decomposition energy efficiency was. And when the amount of flow was much, and the more discharge input power increased, the more ozone generated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.390-390
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• 2011

급속한 산업의 발달은 심각한 환경오염 및 에너지 문제를 가져왔다. 이를 해결하기 위하여 무한한 에너지원인 태양에너지를 원천으로 하는 친환경 정화소재로서의 광촉매(photocatalyst)를 통하여 인류의 에너지를 확보하는 것에 대한 관심이 급격하게 증가하고 있는 추세이다. 현재 광촉매로 가장 많이 사용되는 $TiO_2$의 경우 뛰어난 광활성에도 불구하고, 상대적으로 넓은 밴드갭(band gap) 으로 인한 가시광 응답성의 부재로 이를 해결하기 위한 많은 연구가 진행되고 있다. 따라서 본 연구에서는 PIII&D (plasma immersion ion implantation & deposition) 장비를 통하여 -60 kV의 펄스 고전압을 인가해 $TiO_2$에 좁은 band gap을 갖는 반도체를 이온주입하여 가시광 응답성을 갖는 양자점 감응(Quantum dot sensitized)형 광촉매를 제작하였다. 이온주입 후 시료의 chemical state와 crystallinity를 확인하기 위하여 X-ray photoelectron spectroscopy와 X-ray diffraction measurement를 이용하여 분석을 수행하였으며, 이러한 공정을 통해 제작된 양자점 감응형 광촉매의 가시광 응답성을 확인하기 위하여 UV/Vis 스펙트럼을 측정하였다. 또한 광촉매의 효율을 확인하기 위해 물 분해 장치(water splitting device) 를 제작하여 수소와 산소를 생성하였다.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.1-6
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• 2000

In this experiment, we made the plasma reactor which adhere needle electrode in order to treat safely an NOx which was included in the gas. Also we experimently investigated characteristics of equipment and inspected efficiency. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and gas flow rate was set at 2 ${\iota}$/min. As a reaction characteristics of NOx, when discharge input power was high, NO concentration decreased and when the oxygen concentration increased, the NO decomposition was easy and decomposition energy efficiency was high. Also in case that NO concentration increased, NO decomposition energy efficiency was high but decomposition rate was low. The characteristics of ozone, when discharge input power was high, ozone increased and when $NO/N_2$ concentration increased, the ozone decreased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.708-718
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• 2020

Offensive odor is recognized as a social environmental problem due to its olfactory effects. Ammonia(NH₃), hydrogen sulfide(H₂S) and benzene(C₆H₆) are produced from various petrochemical plants, public sewage treatment plants, public livestock wastes, and food waste disposal facilities in large quantities. Therefore efficient decomposition of offensive odor is needed. In this study, the removal efficiency of atmospheric-pressure plasma operating at an ambient condition was investigated by evaluating the concentrations at upflow and downflow between the plasma reactor. The decomposition of offensive odor using plasma is based on the mechanism of photochemical oxidation of offensive odor using free radical and ozone(O₃) generated when discharging plasma, which enables the decomposition of offensive odor at ordinary temperature and has the advantage of no secondary pollutants. As a result, all three odor substances were completely decontaminated within 1 minute as soon as discharging the plasma up to 500 W. This result confirms that high concentration odors or mixed odor materials can be reduced using atmospheric-pressure plasma.