• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.30-33
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• 2006

Onset voltage plays a crucial role in the design of a spray microthruster. This paper presents an analytical electrostatic model to predict the behavior of onset voltage in an array of emitters. The basic idea of this method is to superimpose the electric potentials obtained from each individual emitter in an array of emitters. The results show that if one emitter operates and the other neighboring emitters are dry, the potential required for cone-jet spraying generally increases as the emitter spacing decreases (due to electrical shielding). However at very close spacing the potential can decrease. If all emitters operate at the same time, the phenomenon that even at very close spacing the onset voltage required for cone-jet spraying increases merely as the emitter spacing decreases.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2089-2097
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• 2014

Negative corona onset characteristics of the stranded conductors based on the ultra-high voltage (UHV) corona cage were studied in the paper. Based on the corona self-sustaining criterion in extreme uneven electric fields and the secondary emission process of the photoelectrons, the corona onset calculation model in the UHV corona cage is established and the corona current tests of the single LGJ900-75, 6 bundle LGJ900-75, 8 bundle LGJ400-35 conductors in dry and rain conditions were done in the UHV corona cage, and the rain rates are 2.4 mm/h, 20 mm/h and 30 mm/h. Corona onset electric field strength is gained by E-I tangent method, and the onset electric field strength in dry condition proves that the calculation model can be used to calculate the corona onset characteristics of the bundle conductors in the UHV corona cage. A further analysis proves that: the negative corona onset voltage of the conductor increases with the bundle number and the diameter of the sub conductor, but decreases with the bundle space in the corona cage. The onset electric field strength is influenced little by bundle space and bundle number, but decreases with the increase of the diameter of the sub-conductor. The surface irregularity coefficient decreases with the rain rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.572-578
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• 2001

This study conducts a laboratory measurement on a cylindrical electrostatic precipitator(ESP) with a 30mm-diameter cylinder. Several kinds of test aerosols are generated with an atomizer and a diffusion dryer. The effects of applied voltage, flow state, gas velocity, and gas temperature on the electrical characteristics of the precipitator and onset of corona are experimentally investigated. The corona onset voltage is decreased, as diameter of discharge electrode wire becomes small or temperature of the precipitator increases. As the fluid velocity or particle load in the precipitator increases, the corona current is decreased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.95-100
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• 2006

Electrostatic precipitators(EPs) have low pressure drop and high dust collection efficiency and are widely used for industrial dust collectors. The current-voltage characteristics, which are important to maintain high dust collection efficiency, depend on several factor: discharge electrode shape, gas flow property, dust loading etc. In this study, experiments are performed to investigate the current-voltage characteristics of the corona discharge of various electrode geometries and an empirical model is proposed to predict current-voltage characteristics of the corona discharge. The corona onset voltage correction coefficient$(\alpha)$ and the geometry correction coefficient$(k_g)$ are used to the conventional equation for wire-plate type discharge electrode. The corona onset voltages are -6.3kV and almost constant when the numbers of discharge pins are varied from 3 to 9. The length of discharge pins has very sensitive effects on the corona onset voltage. They are increased from -6.3 to -7.8kV when the discharge pin length are 8.5 and 4.5mm, respectively. The empirical model shows good agreement with experimental results and can predict the effects of discharge pin length and number.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.372-375
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• 2009

We have studied on plasma diagnosis, characteristics of the glow discharge at the several different conditions of pressure, discharge current and such. The discharge onset voltage and onset current decreased as pressure increase, the general trend was nearly in agreement with the left regions of Paschen's curve. As normal glow discharge, discharge voltage was constant according to discharge current.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.107-111
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• 2010

This paper has presented the dependence of the threshold voltage on back gate bias and drain voltage for FinFET. The FinFET has three gates such as the front gate, side and back gate. Threshold voltage is defined as the front gate bias when drain current is 1 micro ampere as the onset of the turn-on condition. In this paper threshold voltage is investigated into the analytical potential model derived from three dimensional Poisson's equation with the variation of the back gate bias and drain voltage. The threshold voltage of a transistor is one of the key parameters in the design of CMOS circuits. The threshold voltage, which described the degree of short channel effects, has been extensively investigated. As known from the down scaling rules, the threshold voltage has been presented in the case that drain voltage is the 1.0V above, which is set as the maximum supply voltage, and the drain induced barrier lowing(DIBL), drain bias dependent threshold voltage, is obtained using this model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.454-456
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• 2017

Current and capacitance-voltage characteristics of tunnel field effect transistor (TFET) with various quantum models were investigated. Density gradient, Bohm quantum potential (BQP), and Vandort quantum correction are used with calibrating against Schrodinger-Poisson model. Drive-currents in all models. are decreased. When only BQP is used, SS and $V_{onset}$ are fixed but drive-current is decreased 3 times more than those of no quantum model. And When BQP with Vandort and density gradient are used, SS increased more than 40 mV./dec and $V_{onset}$ shifted as 0.07 eV.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.1
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• pp.15-21
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• 2002

We investigated effects of electrical, physical, and chemical parameters on energy transfer, NO conversion, and light emission in the dielectric barrier discharge (DBD) process. As gap distance between electrodes increased, discharge onset voltage increased. However, as gap distance between electrodes increased, electric field which initiates discharge showed approximately the same value, 30kV/cm. The discharge onset voltage of the coarse surface electrode was lower than that of the smooth surface electrode. And, energy transfer was slightly enhanced in the coarse electrode condition. However, NO conversion rate decreased with the coarse surface electrode because more uniform discharge can be obtained on the smooth surface electrode. The NO conversion rate increased with decreasing the initial concentration, so the DBD process is more feasible in the lower concentration condition. The variation of gas residence time tested at the same energy density in the experiment did not affect on the NO conversion. The result shows that the NO conversion rate mainly depends on the energy density. The DBD process is able to adjust on plasma-photocatalyst process because it emits the short wavelength light in the range of ultraviolet. The intensity of light emission increased with the increase of the energy transfer to the reactor and the gas flow rate.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.264-268
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• 1999

A new implementation strategy for the flux weakening control of a Surface Mounted Permanent Magnet Synchronous Motor (SPMSM) is proposed. It is implemented based on the output of the synchronous PI current regulator-reference voltage to PWM inverter. The onset of flux weakening and the level of the d-axis current are adjusted by the outer voltage regulation loop to prevent the saturation of the current regulator. The characteristics of this flux weakening scheme include no dependency on the machine parameters, the guarantee of current regulation on any operating condition, and fast transition into and out of the flux weakening mode. Experimental results at various operating conditions including 4-quadrant operation are presented to verify the feasibility of the proposed control scheme.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.563-565
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• 1993

This paper describes ozone concentration and discharge characteristics in flowing $O_2$ with variation of Re at high voltage nozzle(HVN). HVN type ozonizer is equipped with ten nozzle. The important conclusions obtained from this paper are as follows. For constant pulse width(Pw) and pulse frequency(Pf) the more Re increases, the higher corona onset voltage(Vc) rise. Vc is inversely proportional to Pw and Pf. Ozone concentration($O_{3con}$) increases with less Re for constant Pw and Pf. $O_{3con}$ increases with less Pw. $O_{3con}$ is proportional to Pf.