J.H. Park

Stable and high emission current from carbon nanotube paste with spin on glass

We prepared carbon nanotube (CNT) pastes with different inorganic binders such as glass frit and spin on glass (SOG). MWNT powders grown by CVD were used for electron emissive source. The three-roll mill process was carried out for mixing and dispersion of CNT powders in organic vehicle as polymer matrix. CNT paste was printed onto various substrates such as an indium thin oxide (ITO) coated soda lime glass and a nickel plate. Then CNT paste was sintered under different ambient and temperature. For the analysis of the surface morphology of the cathode layer, field-emission scanning electron microscopy (FESEM) was used. The FE characteristics of CNT paste were measured in a high vacuum chamber with a parallel diode type configuration at 5/spl times/10/sup -6/ Torr. We obtained stable and high emission current from CNT paste with SOG. Our experiments have shown that CNT paste with SOG can use as efficient electron emitter in vacuum nanoelectronics such as radio frequency amplifier, field emission display and X-ray tube.

Field emission properties of plasma treated multiwalled carbon nanotube cathode layers

Improved field emission stability and lifetime have been observed for multiwalled carbon nanotube (MWCNT)-paste cathode layers, after plasma conditioning. Initially, MWCNT paste was synthesized and screen printed on an indium tin oxide coated glass substrate to obtain the cathode layers. These cathode layers were exposed to the Xe∕Ne plasma for a period of ∼1 or ∼3min under different biasing conditions (∼250 and ∼300V). The scanning electron microscopy micrographs, recorded for the untreated (virgin) and plasma treated cathode layers, showed significant variations in their morphology. The field emission analysis showed that the onset macroscopic field was increased from its virgin value of ∼4.65to∼9.05±0.05V∕μm for the plasma treated samples, with a subsequent decrease in the mean field-enhancement factor γav from 1251±13 to 779±43, computed from the Fowler-Nordheim plot. The variations in the current density was measured as a function of time, under low (∼10−6Torr) as well as high (∼10−8Torr) vacuum cond...

Control method of propulsion control device for AC railway vehicle

Railway vehicle is classified into the AC and DC railway vehicle according to the distribution of the local environment. DC railway vehicle is directly supplied to the DC power from the power line to drive the inverter but AC railway vehicle is complicated to control and drive sequence as compared to DC vehicle because of the structure for controlling the inverter and converter at the same time. In this paper we describe the sequence and method for controlling a railway driving vehicle on AC power line and confirm the analysis and control performance through computer simulation.

Effect of electrical aging on emission stability of carbon nanotube field emitter

In this study, the effects of electrical aging on emission stability of screen-printed carbon nanotube(CNT) emitter is investigated. Results show that stable and uniform emission currents from CNT emitter are obtained during the multiple field emission cycling. During the initial stage of electrical aging, an emission current fluctuation is observed and is gradually reduced and electron emission stabilized as time passes.

Screen printed carbon nanotube field emitter array for lighting source application

Photosensitive carbon nanotube (CNT) paste was synthesized with spin on glass (SOG) as inorganic binder. The field emission characteristics of this CNT paste was studied. CNT field emitter arrays (FEAs) was then fabricated using screen-printing method, photolithography and vacuum-in-line sealing technology. It is concluded that the diode type FEA using CNT paste with SOG can be used for lighting system applications such as the back light unit in TFT-LCD.