• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1732-1734
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• 2001

The purpose of this experiment was to develope Triggered Vacuum Switch(TVS) and to improve understanding of the high current vacuum arc phenomena in the TVS. The TVS has an array of rods of alternate polarity in which a fixed gap spacing is maintained between the rods. The cross section of each rod has trapezoidal shape. Breakdown of the TVS produced high current vacuum arc plasma. A spectroscopic measurement was performed over 20 kA peak current in the center of electrodes, in the vicinity of cathode, and outside electrodes. The electrode material tested was Fe. Measured Fe spectrum range was from 200 nm to 900 nm. Measurement result showed that over 90 percent of the charge states were FeII and the others were FeI and FeIII. The electron temperature was determined from the relative line intensity ratio methode of FeII system by assuming the local thermal equilibrium(LTE). The electron temperature at the center of electrodes was measured as 1.5 eV at 26 kA peak current. The electron temperature varied with its peak current. Intensity of spectrums is the highest in the vicinity of the cathode. Further we will also present study result of the diode phenomena in the TVS.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.297-303
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• 2008

$LiNiO_2$ cathode powders with fine size have been synthesized by spray pyrolysis from the spray solution with citric acid and ethylene glycol. The as-prepared powders with spherical shape, porous structure and micron size turned into $LiNiO_2$ powders with micron size and regular morphology after post-treatment at $800^{\circ}C$. The initial discharge capacities of the $LiNiO_2$ powders changed from 199 to 171mAh/g when the concentrations of the citric acid and ethylene glycol added to the spray solutions were changed from 0 to 1 M. The maximum initial discharge capacity of the $LiNiO_2$ powders obtained from the spray solution with citric acid and ethylene glycol was 198 mAh/g when the lithium component added to the spray solution was 6 mol% excess of the stoichiometric amount. The discharge capacities of the fine-sized $LiNiO_2$ powders dropped from 198 to 163 mAh/g by the 30 th cycle at a current density of 0.1 C.

• Journal of the Korean Electrochemical Society
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• v.15 no.2
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• pp.109-114
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• 2012

The cathode catalyst layer in polymer electrolyte membrane fuel cells (PEMFCs) was fabricated with anodic aluminum oxide (AAO) template and its structure was characterized with scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The SEM analysis showed that the catalyst layer was fabricated the Pt nanowire with uniform shape and size. The BET analysis showed that the volume of pores in range of 20-100 nm was enhanced by AAO template. The electrochemical properties with the membrane electrode assembly (MEA) were evaluated by current-voltage polarization measurements and electrochemical impedance spectroscopy. The results showed that the MEA with AAO template reduced the mass transfer resistance and improved the cell performance by approximately 25% through controlling the structure of catalyst layer.

• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.52-57
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• 2015

The focal spot of electron beam depending on the anode angle in the structure and major parts of the X-ray tube was investigated by the OPERA-3D/SCALAR simulation program. The simulation worked on four spaces with with two spaces, including anode and cathode of X-ray tube, by applying the finite element method analysis. The analytical model and dimension for the emission orbit of thermal electrons made from one filament of the focused X-ray cathode is affected to the penumbra of detector for the X-ray depending on any real focal spot size. The model shape of focusing cap and focusing tube with an anode target angle and a cathode filament is analyzed by the current density distribution of thermal electrons. The focusing width of thermal electrons for the X-ray tube depended on the anode angle (${\theta}$). The focusing value of electron beams at a region of anode angle having $10^{\circ}{\sim}17^{\circ}$ maintained to below value of $70{\mu}m$. The minimum focal size of the electron beam was $40{\mu}m$ at an anode angle of $15^{\circ}$. The focused X-ray tube of many variables depended on the thermionic emission of hot electrons from the target trajectory. The focusing tube will contribute to the real design of X-ray for the development of future diagnosis medical device.

• Resources Recycling
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• v.31 no.6
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• pp.81-91
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• 2022

The use of lithium-ion batteries increases significantly with the rapid spread of electronic devices and electric vehicle and thereby an increase in the amount of waste batteries is expected in the near future. Therefore, studies are continuously being conducted to recover various resources of cathode active material (Ni, Co, Mn, Li) from waste battery. In order to recover the cathode active material, black mass is generally recovered from waste battery. The general process of recovering black mass is a waste battery collection - discharge - dismantling - crushing - classification process. This study focus on the crushing/classification process among the processes. Specifically, the particle size distribution of various samples at each crushing/classification step were evaluated, and the particle shape of each particle fraction was analyzed with a microscope and SEM (Scanning Electron Microscopy)-EDS(Energy Dispersive Spectrometer). As a result, among the black mass particle, fine particle less than 74 ㎛ was the mixture of cathode and anode active material which are properly liberated from the current metals. However, coarse particle larger than 100 ㎛ was present in a form in which the current metal and active material were combined. In addition, this study developed a PBM(Population Balance Model) system that can simulate two-species mixture sample with two different crushing properties. Using developed model, the breakage parameters of two species was derived and predictive performance of breakage distribution was verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.432-439
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• 2003

Inconel 690 for nuclear steam generator tube has more Chromium than the conventionally used Inconel 600 in order to increase the corrosion resistance. To evaluate the tribological characteristics of Inconel 690 under fretting condition the fretting tests were carried out in air and elevated temperature water. Fretting tests of the cross-cylinder type were done under various vibrating amplitudes and applied normal loads in order to measure the friction forces and wear volumes. From the results of fretting wear tests. the wear of Inconel 690 can be predictable using the work rate model. The amounts of friction forces were proportional to relative movement between two fretting surfaces. The friction coefficients were decreased as increasing the normal loads and deceasing the vibrating amplitudes. Depending on fretting environment, distinctively different wear mechanisms and often drastically different wear rates can occur It was found that the fretting wearfactors in air and water at 2$0^{\circ}C$, 5$0^{\circ}C$, and 8$0^{\circ}C$ were 7.38 $\times$ $10^{-13}$$Pa^{-1}$, 2.12 $\times$$10^{-13}$$Pa^{-1}$, 3.34$\times$$10^{-13}$$Pa^{-1}$and 5.21$\times$$10^{-13}$$Pa^{-1}$, respectively flexibility to model response data with multiple local extreme. In this study, metamodeling techniques are adopted to carry out the shape optimization of a funnel of Cathode Ray Tube, which finds the shape minimizing the local maximum principal stress. Optimum designs using two metamodels are compared and proper metamodel is recommended based on this research.

• Journal of Information Display
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• v.2 no.3
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• pp.60-65
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• 2001

Lateral type poly-silicon field emitters were fabricated by utilizing the LOCOS (Local Oxidation of Silicon) process. For the implementation 'of an ideal field emission device with quasi-zero tunneling barrier, a new and fundamental approach has used conducted by introducing an intelligent carbon-based thin layer on the cathode tip surface via a field-assisted self-aligning of carbon (FASAC) process. Fundamental lowering of the turn-on field for the electron emission was feasible through the control of both the tip shape and surface barrier height.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.85-93
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• 2005

Isotopes of alkali and alkaline earth metals (AM and AEM) are the main contributors to the heat load and the radiotoxicity of spent fuel (SF) . These components are separated from the SF and dissolved in a molten LiCl in an electrolytic reduction process. A mass transfer model is developed to describe the diffusion behavior of Cs, Sr, and Ba in the SF into the molten salt. The model is an analytical solution of Fick's second law of diffusion for a cylinder which is the shape of a cathode in the electrolytic reduction process. And the model is also applied to depict the concentration profile of the oxygen ion which is produced by the electrolysis of Li$_{2}$O. The regressed diffusion coefficients of the model correlating the experimentally measured data are evaluated to be greater in the order of Ba, Cs, and Sr for the metal ions and the diffusion of the oxygen ion is slower than the metal ions which implies that different mechanisms govern the diffusion of the metal ions and the oxygen ions in a molten LiCl.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.12
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• pp.785-790
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• 1999

This research has been carried out to develop a low-energy large-aperture pulsed electron beam generator (LELA), 200keV 1A, for industrial applications. One of the most important feature of this electron beam generator is large electron beam cross section of $190cm^2$. Low energy electron beam generators have been used for water cleaning, flue gas cleaning, and pasteurization, etc. In these applications the cross sectionof the e-beam is related to reaction efficiency. Another important feature of this LELA EB generator is easy maintenance because of its simple structure and relatively low vacuum operation compared to the conventional EB generators. The conventional EB generators need to be scanned because the small cross section thermal electron emitters are used in the conventional EB generators which have small EB cross section. In this research, we use the secondary electrons generated by ion bombardment on the HV cathode surface as a electron source. Therefore we can make any shape of EB cross section without scanning.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.400-406
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• 2015

This study researched the structure of the source of an ion milling machine used to fabricate a scanning electron microscope (SEM) sample. An ion source is used to mill out samples of over 1 mm dimension using a broad ion beam to generate plasma between the anode and cathode using a permanent magnet. To mill the sample in the vacuum chamber, the ion source should be greater than 6 kV for a positive ion current over $200{\mu}A$. To discover the optimum operating conditions for the ion miller, the diameter of the extractor, anode shape, and strength of the permanent magnet were varied in the experiments. A silicon wafer was used as the sample. The sputter yield was measured on the milled surface, which was analyzed using the SEM. The wafer was milled by injecting 1 sccm of argon gas into the 0.5 mTorr vacuum chamber.