• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.433-433
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• 2016

Carbon nanotubes (CNT) emitter has widely become an attractive mechanism that draws growing interests for cold cathode field emission. CNT yarns have demonstrated its potential as excellent field emitters. It was demonstrated that a small focal spot size was achieved by manipulating some electrical parameters, such as applied bias voltage at the mesh gate, and electrostatic focal lenses, geometrical parameters, such as axial distances of the anode, and the electrostatic focal lens from the cathode assembly, and the dimension of the opening of the electrostatic lens. Electrical-optics software was used to systematically investigate the behavior of the electron beam trajectory when the aforementioned variables were manipulated. The results of the experiment agree with the theoretical simulation results. Each variable has an individual effect on the electron beam focal spot size impinging on the target anode. An optimum condition of the parameters was obtained producing good quality of X-ray images. Also, MWCNT yarn was investigated for field emission characteristics and its contribution in the X-ray generation. The dry spinning method was used to fabricate MWCNT yarn from super MWCNTs, which was fabricated by MW-PECVD. The MWCNT yarn has a significant field emission capability in both diode and the triode X-ray generation structure compared to a MWCNT. The low-voltage-field emission of the MWCNT yarn can be attributed to the field enhancing effect of the yarn due to its shape and the contribution of the high-aspect-ratio nanotubes that protrude from the sides of the yarn. Observations of the use of filters on the development of X-ray images were also demonstrated. The amount of exposure time of the samples to the X-ray was also manipulated. The MWCNT yarn can be a good candidate for use in the low voltage field emission application of X-ray imaging.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.695-700
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• 2014

Proton Exchange Membrane Fuel Cells (PEMFC) can generate hydrogen and oxygen from water by electrolysis. But the electrode and polymer electrolyte membrane degrade rapidly during PEM water electrolysis because of high operation voltage over 1.7V. In order to reduce the rate of anode electrode degradation, unsupported $IrO_2$ catalyst was used generally. In this study, Pt/C catalyst for PEMFC was used as a water electrolysis catalyst, and then the degradation of catalyst and membrane were analysed. After water electrolysis reaction in the voltage range from 1.8V to 2.0V, I-V curves, impedance spectra, cyclic voltammograms and linear sweep voltammetry (LSV) were measured at PEMFC operation condition. The degradation rate of electrode and membrane increased as the voltage of water electrolysis increased. The hydrogen yield was 88 % during water electrolysis for 1 min at 2.0V, the performance at 0.6V decreased to 49% due to degradation of membrane and electrode assembly.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1343-1346
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• 2005

Self assembled monolayers (SAM) are generally used at the anode/organic interface to enhance the carrier injection in organic light emitting devices, which improves the electroluminescence performance of organic devices. This paper reports the use of SAM of 1-decanethiol (H-S(CH2)9CH3) at the cathode/organic interface to enhance the electron injection process for organic light emitting devices. Aluminum (Al), tris-(8-hydroxyquionoline) aluminum (Alq3), N,N'-diphenyl-N,N'-bis(3 -methylphenyl)-1,1'- diphenyl-4,4'-diamine (TPD) and indium-tin-oxide (ITO) were used as bottom cathode, an emitting layer (EML), a hole-transporting layer (HTL) and a top anode, respectively. The results of the capacitancevoltage (C-V), current density -voltage (J-V) and brightness-voltage (B-V), luminance and quantum efficiency measurements show a considerable improvement of the device performance. The dipole moment associated with the SAM layer decreases the electron schottky barrier between the Al and the organic interface, which enhances the electron injection into the organic layer from Al cathode and a considerable improvement of the device performance is observed. The turn-on voltage of the fabricated device with SAM layer was reduced by 6V, the brightness of the device was increased by 5 times and the external quantum efficiency is increased by 0.051%.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.31-37
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• 2009

Hybrid ballast for field emission lamp with CNT (carbon nano tube) emitter is proposed. Hybrid ballast consists of a high voltage dc part and hi-polar pulse generation part. Field emission lamp with CNT lamp is composed of three electrodes (anode, gate, and cathode). High voltage dc part is for anode and gate and hi-polar pulse generation part is for gate and cathode in CNT triode respectively. The experimental results demonstrate that the proposed topology is good for driving CNT lamp. To protect the lamp and ballast, OCP (Over Current Protection), OVP (Over Voltage Protection), and OTP (Over Temperature Protection) are added and the experimental results demonstrate that the proposed method is good for driving field emission lamp with CNT emitter.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.38-46
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• 2022

Two different gas diffusion layers having noticeable differences in micro-porous layer's (MPL's) crack were studied as a substrate for the gas diffusion electrode (GDE) with different binder/carbon (B/C) ratios in high-temperature polymer electrolyte fuel cell (Ht-PEMFC). As a result, the performance defined as the voltage at 0.2 A/cm² and maximum power density from the single cells using GDEs from H23 C2 and SGL38 BC with different B/C ratios were compared. GDEs from H23 C2 showed a proportional increase of the voltage with the binder content on the other hand GDEs from SGL38 BC displayed a proportional decline of the voltage to the binder content. It was revealed that MPL crack influences the structure of catalyst layer in GDEs as well as affects the RC_athode which is in close connection with the Ht-PEMFC performance.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.499-504
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• 2015

The composite anodes of expanded graphite (EG) and multiwall carbon nanotube (MWCNT) for microbial fuel cells were fabricated by using coal tar pitch (CTP) binder containing nickel (Ni), and the effect of the anodes with the binders on the performance of the MFCs were examined in a batch reactor. During the start-up of the MFCs, quick increase in voltage was observed after a short lag phase time, indicating that the CTP binder is biocompatible. The biomass attatched on the anode surface was more at higher Ni content in the binder, as well as at smaller amount of CTP binder for the fabrication of the anode. The internal resistance of the MFC was smaller for the anode with more biomass. Based on the results, the ideal combination of CTP and Ni for the CTP binder for anode was 2 g and 0.2 g, respectively. The maximum power density was $731.8mW/m^2$, which was higher 23.7% than the anode with Nafion binder as control. The CTP binder containing Ni for the fabrication of anode is a good alternative in terms of performance and economics of MFCs.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.75-80
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• 1999

Li-ion cells employ lithium transtion metal oxide as the cathode material and carbon as anode material. To manufacture Li-ion cell with higher capacity and better cycle life, the utilization of electrode materials should be as high as possible without lithium deposition onto the carbon surface during charging. A careful design of cell balance between cathode and anode materials as well as a proper charge method is a key factor to design Li-ion cell with long cycle life. In this study, we investigated the effect of cathode/anode weight ratio on the performance of $LiCoO_2/MPCF$ cell. First we evaluated the charge-discharge behaviours of half-cells. And cylindrical Li-ion cells were fabricated using graphitized MPCF anode and $LiCoO_2$ cathode. The voltage profiles for each half-cell in $LiCoO_2/MPCF$ cell were measured by using lithium metal as a reference electrode. Also, we evaluated the cyclic performance of $LiCoO_2/MPCF$ cells according to weight ratio. From the result of experiment $LiCoO_2$ cathode utilization was independent of weight ratio, but MPCF anode utilization was dependant on weight ratio. Also, the optimal weight ratio of $LiCoO_2/MPCF$ cell was found to be $2.0\~2.2$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.7
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• pp.530-532
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• 1999

A new lateral device entitled SB-DCEST(segmented p-base dual-channel emitter switched thyristor), which suppresses the snapback is proposed and successfully fabricated. The proposed device effectively suppressed the snapback phenomenon by employing the gigh resistance in self-aligned segmented p-base when compared with the conventional DCEST. The experimental results show that the SB-DCEST has the low forward voltage drop of 4.3 V at anode current of $150 A/cm^2$ with the eliminated snap-back regime, while conventional DCEST exhibits higher forward voltage drop of 5.3 V.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.319-329
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• 2004

The electrorefining experiments with an anode composed of U, Y, Gd, Nd and Ce (or U, Gd, Dy and Ce) were carried out in the KC1-LiCl eutectic melt at $500^{\circ}C$, Uranium was the major component in the cathode deposits at the high initial uranium concentration, and the separation factors of the uranium with respect to the rare earths (REs) were calculated according to the applied voltage and the uranium concentration in the molten salt. The current efficiency was inversely in proportion to the applied voltage in the range of 1.0 V to 1, 9 V (vs. STS304L). The dependency of the applied voltage on the current efficiency as well as the deposition rate was discussed in terms of the microstructural feature and crystal structure of the deposit.

• ETRI Journal
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• v.35 no.6
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• pp.1164-1167
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• 2013

We correlate the failure in miniature X-ray tubes with the field emission gate leakage current of gated carbon nanotube emitters. The miniature X-ray tube, even with a small gate leakage current, exhibits an induced voltage on the gate electrode by the anode bias voltage, resulting in a very unstable operation and finally a failure. The induced gate voltage is apparently caused by charging at the insulating spacer of the miniature X-ray tube through the gate leakage current of the field emission. The gate leakage current could be a criterion for the successful fabrication of miniature X-ray tubes.