• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.261-261
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• 2013

The smart design of nanocatalysts can improve the catalytic activity of transition metals on reducible oxide supports, such as titania, via strong metal-support interactions. In this work, we investigatedtwo-dimensional Pt nanoparticle/titania catalytic systems under the CO oxidation reaction. Arc plasma deposition (APD) and metal impregnation techniques were employed to achieve Pt nanoparticle deposition on titania supports, which were prepared by multitarget sputtering and sol-gel techniques. APD Pt nanoparticles with an average size of 2.7 nm were deposited on sputtered and sol-gel-prepared titania films to assess the role of the titania support on the catalytic activity of Pt under CO oxidation. In order to study the nature of the dispersed metallic phase and its effect on the activity of the catalytic CO oxidation reaction, Pt nanoparticles were deposited in varying surface coverages on sputtered titania films using arc plasma deposition. Our results show an enhanced activity of Pt nanoparticles when the nanoparticle/titania interfaces are exposed. APD Pt shows superior catalytic activity under CO oxidation, as compared to impregnated Pt nanoparticles, due to the catalytically active nature of the mild surface oxidation and the active Pt metal, suggesting that APD can be used for large-scale synthesis of active metal nanocatalysts.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.281-283
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• 2006

This paper presents two new circuit topologies of DC bus lineside active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200V-rms or AC 400V-rms input voltage source. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. The effectiveness of these new DC-DC converters topologies is proved for low voltage and large current high efficiency DC-DC power supplies as TIG arc welding machine from a practical point of view.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.167-169
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• 1998

Recently $SF_6$ gas circuit breakers utilizing the thermal-expansion principle are increasingly used in distribution power system. Active researches and developments have been conducted to reduce the size and weight, and to improve the interrupting performance of the circuit breakers. It was first developed a programme which could show the hot gas flowing into the thermal-expansion arc chamber. This programme, using so-called FLIC method basically, adopted 'Simplified Enthalpy Arc Model' which was somewhat modified to estimate the arc quenching process. The computation by it was compared with the measured results of the pressure rise in the chamber, and both showed fairly good agreement.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.182-184
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• 2004

GTAW of titanium using flux cored wire was exploited. Flux cored wire with MgF$_2$ resulted in 60% deeper penetration than conventional active GTAW which applys fluxes in the form of paste. Emission spectroscopy of the arc with MgF$_2$ showed Ti II peak, indicating higher temperature arc. Elux cored wire formed weld metal with reasonably low oxygen content.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.172-175
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• 2006

Steam reforming of methane using Xe-arc solar simulator was studied for converting solar radiation into energy foam that one can readily utilize. The Xe-arc lamp produce a spectrum similar to that of the sun. SiC ceramic foam, resist high temp.$(>900^{\circ}C)$, is used to catalytically active foam absorber, and to support of reforming catalyst. The catalyst on the surface of foam were directly irradiated with solar simulated xe-light in order to carry out the steam reforming of methane. The reactor was made of stainless steel and quartz window was located on a place of the xe-light irradiation and temperature was controlled using K-type thermocouple in contact with catalyst located inside the reactor. The result show that a possibility of solar reforming using catalytically active foam absorber is exist.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.41.1-41.1
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• 2019

The stability analysis of coronal magnetic structures is important for studying the initiation of solar flares and eruptions. In order to understand the flare onset process, we first reconstructed the 3D coronal magnetic structures of active region 12371 with an M6.5 flare using a nonlinear force-free field (NLFFF) model based on vector magnetic fields. The NLFFFs successfully produce the observed sigmoidal structure which is composed of two branches of sheared arcade loops. The stability analysis were examined for three representative MHD instabilities: the kink, the torus, and the double arc instabilities. Our stability analysis shows that the two branches of sheared arcade loops are quite stable against the kink and torus instabilities, but unstable against the double arc instability before the flare occurrence. Finally, we discuss a probable onset process of the M6.5 flare.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.57-63
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• 2005

An accurate system modeling in the underground water analysis requires many accurate parameters on the spot, which have a huge volume, because it may be generated more inaccurate products than to use mathematical analytical solution in a case that a degree of permeation, undercurrent coefficients, boundary conditions, and so on, are inadequately estimated. Recently, handling these parameters easily has been an active area of research. In this paper, we propose a new method which handles these parameters easily and accurately for a system model management using a well-known MODFLOW model. Also, we incorporate this method into ArcView functions. Results of the proposed system incorporated into ArcView are displayed visually.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.39-46
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• 2002

The purpose of this study was to examine the effects of sensation and sensibility from the rusting sound of silk fabrics. The mechanical properties and sound parameters were measured after recording the rusting sounds of 7 silk fabrics. Then, their relationships were analyzed through the evaluation of subjective sensation and sensibility and found a regression model for the sensibility from the mechanical properties. The adjectives of the sensibility were grouped into four: Elegant, Active, Tough, Modern. Soft and flexible fabrics were related with LPT negatively and induced elegant sensibility. And fabrics of the smoother and less changable to shear direction were related with LPT and Δf, and positively, and occurred active sensibility. On the other hands, rough, bulky, thick, and heavy fabrics were related with ARC and Δf, and induced with tough or modern sensibilities. About the sensibilities according to each fabric, STN8 was the most elegant, STN8-S was the most active, and TWL16 and STN16-N were the toughest.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.164-171
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• 2004

Active control techniques have been used in wide areas of noise and nitration control engineering and a noise barrier is one of them. Omoto's work in 1993 would be one of the fundamental and systematic studies on the actively controlled noise barrier, in which he used equal number of control sources and error sensors. The error sensors were placed uniformly along the top edge of the noise barrier with equal distance apart and the control sources were placed in the exactly same way some distance apart from the error sensors. Since then, a couple of studies were made on the secondary sources'arrangement rather than the optimality of secondary source positions. Shao's results showed that arc shaped arrangement for secondary sources is better than the straight line one, and later work of Yang showed that the more important factor is the average distance between the primary source and secondary sources. However, since these studies were all executed with a simple uniform distribution of the secondary sources along the straight line or arc, it is difficult to conclude which arrangement is superior In order for the fare comparison. the optimality of the source positions in each arrangement must be given in prior. The primary goal of this study is focused on this aspect and some major factors were investigated and compared. The computer simulation results showed that the arc shaped arrangement is marginally better than the straight line one, and more importantly slightly tuned position can greatly improve the performance of the control system.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.162.1-162.1
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• 2015

The use of plasma has increased in bio-application field in recent years. Particularly, water treated by arc discharge or atmospheric pressure plasma has been actively utilized in bio-industry. In this study, we have developed a plasma activated water generating system. For this system, two kinds of plasma sources; dielectric barrier discharge (DBD) plasma and arc discharge plasma have been used. The discharge energy was calculated using the breakdown voltage and current, and the emission spectrum was measured to investigate the generated reactive species. We also analyzed the amount of reactive oxygen and nitrogen species in water using the chemical methods and nitric oxide sensor. Finally, the influence of plasma generated reactive species on the germination and growth of spinach (Spinacia oleracea) was investigated. Spinach is a green leafy vegetable that contains a large amount of various physiologically active organic compounds. However, it is characterized with a low seed germination rate.