• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.209-213
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• 2000

In this paper, the removal rate of NO in a reactor is measured first using nonthermal plasma generated from a wire-cylinder type reactor, then the spatial density distribution of NO particles is investigated using ICCD(Intensified Charged Coupled Device) camera. This research uses nonthermal plasma from electrical discharge to analyze the NO characteristics, and the measurements of NO discharge image and Distribution are performed using the ICCD camera to examine the NO characteristics more closely. Furthermore, the method of Laser Induced Fluorescence (LIF) is used to analyze the particular behavior of NO particles more specifically, to suggest a method of reducing exhaust gas, a serious environmental problem.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.169-178
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• 2001

Among the recent research ideas to reduce hydrocarbon emissions emitted from SI engines till light-off of catalyst since cold start are those exploiting non-thermal plasma technique and photo-catalyst that draws recent attention by virtue of its successful application to practical use to clean up the atmosphere using the feature of its relative independence on temperature. Based on the previous research results obtained with model exhaust gases using an experimental emissions reduction system that utilizes the non-thermal plasma and photo-catalyst technique, further investigation was conducted on a production N/A 1.5 liter DOHC engine during cold start to warm-up. For the effects of non-thermal plasma-photocatalyst combined reactor, 10% concentration reduction was achieved with the fuel component paraffins, and the large increase in non-fuel paraffinic components and acetylene concentrations were similar to those of base condition. However the absolute value was locally a bit higher than those of base condition since the products was made from the dissociation and decomposition of highly branched paraffins by plasma-photocatalyst reactor. Olefinic components were highly decomposed by about 75%, due to these excellent decompositions of olefins which have relatively high MIR values, and the SR value was 1.87 that is 30% reduction from that of base condition, then, the photochemical reactivity was lowered.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.699-707
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• 2007

This study was carried out to investigate the reaction characteristics of corona/catalyst hybrid $DeNO_x$ process. The experiments were performed by using the multi-staged pin-to-hole type corona reactor which is enable to control the pin-to-hole gap and to insert the catalyst. Also, used for this study, were catalysts which commercially used Pt, Pd and $TiO_2$, and oxygen and hydrocarbon ($C_2H_4$) as reagents. In the syn-gas test, at high temperatures in the range of $100{\sim}200^{\circ}C$, the corona-only $DeNO_x$ process did not reduce the $NO_x$ concentration effectively. However in the presence of ethylene and oxygen as reagents, the $NO_x$ removal efficiency was better at these high temperatures than corona-only $DeNO_x$ process. In addition, coronal catalyst hybrid process with $TiO_2$ showed more efficiency of $NO_x$ removal than Pt and Pd catalyst, because the $TiO_2$ catalyst was more active than Pt and Pd catalyst to converse the $NO_2$ to $HNO_3$. Furthermore, at the condition of real diesel exhaust gas, the $DeNO_x$ efficiency of corona/catalyst hybrid process was not good at higher reaction temperature and plasma density.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.85-90
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• 2006

The purpose of this research is to design an imitation boiler similar to the waste heat boiler installed on a plasma melting furnace in order to acquire a capability of a thermal design as to the circulation of heat and the discharge of noxious gas inside a boiler and to improve the efficiency of a waste heat boiler using the CFD (Computation Fluid Dynamics) program. The position of corrosion and the generation of a clinker inside a boiler due to temperature changes, combustion gas flows, and corrosive gases inside a boiler are examined to design the structure of an efficient boiler and recycle energy. As a result of this research, the boiler installed on a plasma melting furnace met the conditions of design by cooling the combustion gases discharged after the second combustion from an exhaust port, originally at 1,200 degrees Celsius, down to around 450 degrees Celsius. On the other hand, the circulation of corrosive gases (SOx and HCL) may lead to the generation of corrosion or a clinker in the upper and lower parts of an exhaust port more easily than any other parts of a boiler. Accordingly, the corrosion on the inside and outside walls of a boiler may result in a shortened lifespan of a boiler and an inability to recycle waste heat in an efficient manner. A prevention against corrosion at high and low temperatures needs to be considered in detail.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.414-419
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• 2006

Effects of water vapor, hydrocarbons, and CO, which are inevitably included in exhaust gases of combustion, on a combined $De-NO_{x}$ process of non-thermal plasma and $NH_{3}$ SCR (Selective Catalytic Reduction) have been investigated. Test results showed that fast SCR reaction enhanced $De-NO_{x}$ rate under the low temperature conditions, $150{\sim}200^{\circ}C$ The present test, however, showed that the role of the fast SCR reaction can be significantly suppressed by addition of hydrocarbons in a non-thermal plasma reactor. Detailed investigation verified that such suppressed role of the fast SCR reaction could be caused by the $NO_{2}/NO_{x}$ ratio modified by aldehydes produced from hydrocarbons in a non-thermal plasma reactor. In addition, the present study was confirmed that the effects of water vapor and CO were not noticeable compared with the hydrocarbon effects.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.86-92
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• 2011

The diagnosis studies of the process of chemical vapor deposition were carried out by using in-situ particle monitor (ISPM) and self-plasma optical emission spectroscopy (SPOES). We used the two kinds of equipments such as the silicon plasma enhanced chemical vapor deposition system with silane gas and the borophosphosilicate glass depositon system for monitoring. Using two sensors, we tried to verify the diagnostic and in-situ sensing ability of by-product gases and contaminant particles at the deposition and cleaning steps. The processes were controlled as a function of precess temperature, operating pressure, plasma power, etc. and two sensors were installed at the exhaust line and contiguous with each other. the correlation of data (by-product species and particles) measured by sensors were also investigated.

• Journal of Powder Materials
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• v.4 no.4
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• pp.243-251
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• 1997

Engine valve-shaped TiAl-Mn intermetallics containing 43.5 to 47.5at%Al (Mn/Al=0.036) are successively fabricated by reactive sintering the elemental powder mixtures near-net shaped by extrusion and die forging. A duplex structure consisted of lamellar grains and equiaxed $\gamma$ grains is developed for all compositions, and the areal fraction of the lamellar grains(or equiaxed $\gamma$ grains) decreases (or increases) with increasing Al content. As Al content increased, the elongation increases with accompanying decrease in yield strength and ultimate tensile strength at both room temperature and 80$0^{\circ}C$. This indicates that the suitable composition is Ti-45at%Al-1.6at%Mn in considering the balance of ambient and elevated tensile properties. The reactive-sintered Ti-45Al-1.6Mn alloy shows superior oxidation resistance not only to the plasma arc melted one but also to the heat resistance steel STR35(representative exhaust valve head material for automotive engine). The reactive-sintered Ti-45Al-1.6Mn alloy coated with an oxidizing scale exhibits a better wear resistance than induction hardened martensitic steel STR11(representative exhaust valve tip material for automotive engine).

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.1-11
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• 2021

To develop technologies for the stable operation of electric propulsion systems, the exhaust plume behavior of electric thrusters was studied using PIC-DSMC(particle-in-cell and direct simulation Monte Carlo). For the numerical analysis, the Simple Electron Fluid Model using Boltzmann relation was employed, and the charge and momentum exchanges due to atom-ion collisions were considered. The results of this study agreed with the plasma potentials measured experimentally. Near the thruster exit, active collisions among particles and charge exchanges created slow ions and fast atoms, which were expected to significantly affect the trajectory and velocity of the thruster exhaust plume.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.540-543
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• 2011

This work is devoted to an experimental investigation on conceptual design of dual consecutive stage micro plasma thruster (${\mu}PT$). Optimization study on the thruster configuration has been performed for various electrode gap distances from 1 mm to 2 mm and the hole diameter from 0.3 mm to 2 mm depending on desired operating conditions and corresponding nozzle design requirement. The operation of ${\mu}PT$ at low pressure from $10^{-1}$ Torr to $10^{-4}$ Torr and at various argon flow rates ranging from 5 sccm to 300 sccm has been studied to understand the physic of plasma and the gas dynamics in details. The specific impulse can reach up to 3000-4000 seconds at low power consumptions from 1 to 5 W. Image of exhaust plume from ${\mu}PT$ will be provided and electrical characteristics is also mentioned in this paper.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.39-39
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• 1999

The KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak is a nuclear fusion experimental device for a long pulse/steady-state plasma operation, adopting fully superconducting magnets. In accordance with completion of the basic design of the torus vacuum vessel and the enclosing cryostat, the vacuum pumping and gas fueling basic design has been developed to fulfil the physics requirements. The ultra-high vacuum pumping and sophisticated gas fueling system of the machine is essential to achieve such roles for optimized plasma performance and operation. Recently the vacuum exhaust system using dedicated pumping ports for the vacuum vessel and cryostat has been modified to meet more reliable and successful performance of the KSTAR[Fig. 1].In order to achieve the required base pressure of 5 x 10-9 torr, the total impurity load to the vessel internal is limited to ~5 x 10-5 torr-1/x, while the cryostat base pressure is kept as ~5 x 105 torr to mitigate the thermal load applied to the superconducting magnets. Each KSTAR fueling system will be separately capable of fueling gas at a rate of 50 torr-1/x, consistent with the given pumping throughput. In order to initiate a plasma discharge in KSTAR, the vacuum vessel is filled to a gas pressure of few 10-6 to few 10-4 torr, and additional gas injection is required to maintain and increase the plasma density during the course of the discharge period.