• 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.

• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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• pp.212-214
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• 2012

Both the electrically positive and negative particles in a cell of quick response-liquid powder display (QR-LPD) are surrounded by conductive electrodes on the upper and lower substrate and the dielectric materials of the barrier ribs. Particles in a cell are attached to or detached from the other materials by image force, electric field, Coulomb's force, and Van der Waals' force. Through these forces, the moving particles form an image but induce clumping phenomena. Particles having a large kinetic energy by a large q/m value crash into the opposite electrode with high speed at a large driving voltage and quickly lose electrically charged material. As a result, these particles are clumped and degrade panel performance. The clumped particles in a cell are observed by microscopic photographs and ascertained by a response time. When the bias voltage is increased to 0.68-0.76 $V/{\mu}m$, particle clumping occurs abruptly and the response time increases sharply. This particle clumping is similarly observed after the number of driving times at the driving voltage (0.42-0.64 $V/{\mu}m$).

• 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$.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.111-112
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• 2000

The breakdown characteristics of surface discharge investigated experimentally agree well with the analytic results of previous reports [1-3] in various electrode geometries. Additionally, we find that the electrode geometry effects on the firing voltage can be understood with the ionization probability relating to the number of priming particles. We have also observed the shape of surface discharge and the surface striations in the gap geometry with the pressure, the applied voltage, and the driving frequency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.741-749
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• 2001

An inhomogeneous hyperbolic electric field is established among two-dimensional quadrupole electrodes to which an ac voltage is applied. Conditions under which charged particles are focused into a narrow axis region of the plug laminar flow are discussed. The aerodynamic forces influence the behavior of the charged particles in the quadrupole electric field. We derived the dimensionless equations of motion of a charged particle in the alternating quadrupole electric field, and discussed particle trajectories and focusing performance in terms of two dimensionless parameters, which are functions of particle size, operating pressure, and the amplitude and frequency of applied AC voltage, with the results of numerical simulations and experiments.

• Carbon letters
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• v.26
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• pp.25-30
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• 2018

The dielectric medium used in electrophoretic displays (EPDs) is required to be an environmentally friendly solvent with high density, low viscosity, and a large electric constant. Hydrofluoroether, a highly fluorinated solvent with eco-friendly characteristics, is regarded as a viable alternative medium for EPDs, owing to the similarity of its physical properties to those of the conventional EPD medium. Surface modification of particles is required, however, in order for it to disperse in the charged solvent. Also, positive/negative charges should be present on the particle surface to enable electrophoretic behavior. In this study, carbon black particles wrapped with positively charged nitrogen (N-CBs) were fabricated by a simple hydrothermal process using a poly(diallyldimethylammonium chloride) solution as a black coloring agent for the EPD. The dispersion behavior of N-CBs was investigated in various solvents.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.91-97
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• 2018

High-energy charged particles are comprised of galactic cosmic rays and solar energetic particles which are mainly originated from the supernova explosion, active galactic nuclei, and the Sun. These primary charged particles which have sufficient energy to penetrate the Earth's magnetic field collide with the Earth's upper atmosphere, that is $N_2$ and $O_2$, and create secondary particles and ionizing radiation. The ionizing radiation can be measured at commercial flight altitude. So it is recommended to manage radiation dose of aircrew as workers under radiation environment to protect their health and safety. However, it is hard to deploy radiation measurement instrument to commercial aircrafts and monitor radiation dose continuously. So the numerical model calculation is performed to assess radiation exposure at flight altitude. In this paper, we present comparison result between measurement data recorded on several flights and estimation data calculated using model and examine the characteristics of the radiation environment in the atmosphere.

• Journal of IKEEE
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• v.23 no.2
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• pp.524-528
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• 2019

Although different types of discharge cells exist, in common it is the primary goal for all discharge cells to have lower drive voltages and higher efficiency characteristics. To improve these factors, many studies are conducted that prolong the discharge path inside the discharge cell or change the composition of the working gas. In this paper, the two-dimensional fluid simulation was used to calculate the discharge voltage (firing voltage and sustain voltage) and the change in luminance and luminous efficacy according to the change in gap distance between discharge electrodes. In addition, we looked at changes in various charged particles, exciting particles and VUV particles, and studied the causes of the resulting values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.66-67
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• 2007

We have developed reflective information display using opposite-charged two particles. An appropriate amount of both the yellow and the black powers are putted between the ITO patterned glass substrate separated with cell gap. The rib maintains the cell gap and prevents the interference between the pixels. When a negative voltage is applied to the upper ITO electrode, the positively charged black powder moves to the upper electrode viewing a black appearance. In case of positive voltage is applied to this electrode white particle is observed. So we analyzed the electrical and optical properties of our charged particle type display panel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1175-1179
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• 2009

We analyze voltage characteristics of charged particle type display according to particle layers and cell gap between two electrodes and ascertain the aging effects by measuring the response time of particles with and without aging process. The threshold/driving/breakdown voltage is proportional to layers of charged particles and cell gap and the response time at driving voltage is faster than that of threshold and breakdown voltage because of different q/m of color and black particles. The analysis of response time is a method of estimation of optical characteristics, driving voltage and particle lumping and these results are promoted by aging process. We use the laser and photodiode to measure response time and optical properties. It has not been studied and reported to analyze the relationship of response time, threshold/driving/breakdown voltage, lumping phenomena, cell gap, and aging process for charged particle type display.