• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.520-527
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• 2006

The electrical discharge and operational characteristics of needle and wire-cylinder corona charger based on current measurements for positive and negative coronas were evaluated and compared. A semi-empirical method was used to determine the ion concentrations in the charging zone and at the outlet of both chargers. Results from experimental investigation revealed that magnitudes of the charging current from the wire-cylinder charger were approximately 3.5 and 2 times smaller than those from the needle charger for the positive and negative coronas, respectively. The ion number concentrations at the outlet for positive corona of both chargers were higher than fur negative corona at the same voltage. Flow and electric fields in the charging zone of both chargers were also analyzed via numerical computation. Strong electric field strength zone was identified and led to high charging and particle deposition. Effect of particle deposition on the evolution of discharge current was presented. It was shown that ions loss inside the wire-cylinder charger was higher than the needle charger The particle deposited on the corona electrodes and on the grounded cylinder caused a great reduction in charging efficiency of both chargers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.501-509
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• 2004

Unipolar diffusion charging of non-spherical particles was investigated for various particle shapes. We researched with TiO$_2$agglomerates produced by the thermal decomposition of titanium tetraisopropoxide (TTIP) vapor. TTIP was converted into TiO$_2$, in the furnace reactor and was subsequently introduced into the sintering furnace. Increasing the temperature in the sintering furnace, aggregates were restructured into higher fractal dimensions. The aggregates were classified according to their mobility using a differential mobility analyzer. The projection area and the mass fractal dimension of particles were measured with an image processing technique performed by using transmission electron microscope (TEM) photograph. The selected aggregates were charged by the indirect photoelectric-charger and the average number of charges per particle was measured by an aerosol electrometer and a condensation particle counter. For the particles of same mobility diameter, our results showed that the particle charge quantity decreases as the sintering temperature increases. This result is understandable because particles with lower fractal dimension have larger capacitance and geometric surface area.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.186-192
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• 2006

We applied a new charging system using the condensation and evaporation method to charge the submicron particles with a uniform charging performance. The monodispersed NaCl submicron particles were condensed by n-butanol vapor and grew up to micron droplets with a same size, regardless of their initial size. Those condensed droplets were charged in an indirect corona charger. The indirect corona charger consisted of the ion generation zone and the particle charging zone. In the ion generation zone, Ions were generated by corona discharge and some of them moved into the particle charging zone by a carrier gas and mixed with the condensed droplet. And finally, the charged and condensed droplets dried through an evaporator to shrink to their original size. The average charge and penetration rate of the particles before and after evaporation were measured by CPC and aerosol electrometer and compared with those of a conventional corona charger. The results showed that the average charge was $5\~7$ charges and the penetration rate was over $90\%$, regardless of the initial particle size.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.7-15
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• 2002

A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

• Particle and aerosol research
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• v.15 no.1
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• pp.15-25
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• 2019

The influences of corona charging parameters on collection efficiency and surface potential of air filters were investigated. A polypropylene filter medium was electrically charged using a corona charger, and the resulting surface potential and filtration efficiency against neutralized KCl particles were measured. The filter media was charged under different conditions of applied voltage, voltage polarity, charging time, and distance between electrodes. In addition, we considered charging both sides of the filter as well as charging one side of the filter. As a result, electrical force obtained by charged fiber affected filtration efficiency when the apply voltage strength was higher than 7 kV. Negatively charged filter had higher filtration efficiency than positively charged filter while the surface potential of the negatively charged filter was slightly lower than those of positively charged filter. Moreover, the filtration efficiency increased as the charging time of filter fiber increased and the distance between electrodes decreased. The filtration efficiency was more sensitive to changes of charging time than to those of electrode distance, and the efficiency of both sides charged filter was higher than that of single side charged filter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.4
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• pp.289-294
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• 2001

A well defined electro-spraying and electro-static precipitator(ESP) experiment is carried out to investigate the charging characteristics of the submicron particles and the monodisperse particles. The basic idea is that the highly charged electro-sprayed droplets will be produced into the gas when the Coulombic repulsive force on the surface is higher than the surface tension of the spraying liquid. During this process many highly charged smaller droplets or ions, if the droplets are completely dried out, will be produced in the space. These charged species will be attached ion the particles and then eventually charge the particles. These charged particles will be easily collected with ESP. The experimental results show that the atomizer generated particles with geometric mean diameter (GMD) of 62nm are charged more than 90% even at the mean face velocity of 2.5m/s at the charging zone.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1013-1018
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• 2011

The charging of 10-nm-class nanoparticles in an electrostatic precipitator (ESP) according to particle charging ratio has been investigated and compared to the diffusion effect of the nanoparticles. The competition between the charging probability and the diffusion loss effect determines the collection efficiency of nanoparticles in the ESP. The collection efficiency of nanoparticles decreased continuously with decreasing particle diameter. This indicates that the partial charging effect of 10-nm-class nanoparticles is more dominant than their diffusion loss effect in the ESP for nanoparticles in the particle size range of less than 10 nm. The charging ratios based on unipolar diffusion charging calculations were in good agreement with the experimental collection efficiencies for nanoparticles less than 10 nm in diameter.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.742-751
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• 2018

Electric vehicles (EV) are emerging as the future transportation vehicle reflecting their potential safe environmental advantages. Vehicle to Grid (V2G) system describes the hybrid system in which the EV can communicate with the utility grid and the energy flows with insignificant effect between the utility grid and the EV. The paper presents an optimal power control and energy management strategy for Plug-In Electric Vehicle (PEV) charging stations using Wind-PV-FC-Battery renewable energy sources. The energy management optimization is structured and solved using Multi-Objective Particle Swarm Optimization (MOPSO) to determine and distribute at each time step the charging power among all accessible vehicles. The Model-Based Predictive (MPC) control strategy is used to plan PEV charging energy to increase the utilization of the wind, the FC and solar energy, decrease power taken from the power grid, and fulfil the charging power requirement of all vehicles. Desired features for EV battery chargers such as the near unity power factor with negligible harmonics for the ac source, well-regulated charging current for the battery, maximum output power, high efficiency, and high reliability are fully confirmed by the proposed solution.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.752-759
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• 2007

For an accurate measurement of aerosol particle size distribution using a differential mobility analyser (DMA), a new calculation process, capable of predicting the masses for the various kinds of water cluster ions generated from a bipolar ionizer, was prepared by improving the previous process. The masses for the 5 kinds of positive and negative water cluster ions produced from a SMAC ionizer were predicted by the improved calculation process. The aerosol particle charging ratios calculated by applying the predicted ion masses to particle charging equations were in good accordance with the experimentally measured ones, indicating that the improved calculation process are more reasonable than the previous one in a mass prediction of bipolar water cluster ions.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.261-266
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• 1998

Since the particles are highly charged in process plasmas, the dynamics of the particles are concerned principally with the effect of the charging amount and polarity. In order to investigate the charging effect of the particles in the plasmas, the known sizes of the mono-dispersed particles with 0.05$\mu\textrm{m}$, 0.07$\mu\textrm{m}$, 0.1$\mu\textrm{m}$and 0.2$\mu\textrm{m}$ diameter are introduced into the DC air-plasmas. The characteristics of the charged particles are measured with a Faraday cup. Results show that the particle charging polarity depends on the concentrations and sizes of the particles and the condition of plasma generation, operating pressure, and power. It is also found that the number of charges per a particle is in the ranges of $10^3$~$ 10^5$.