• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05d
• /
• pp.133-138
• /
• 1996

For the application of hydrogenated amorphous silicon (a-Si:H) p-i-n structural diode as the alpha particle spectroscopy, the induced charge collection was simulated based on a relevant non-uniform charge generation model. The simulation was accomplished for two extreme cases of the incident direction of alpha particle, p-and n-side, respectively. As expected, for the complete charge collection, the hole collection should be severely considered due to its poor mobility and the full depletion bias required. For the comparison of signal corresponding to the detector configuration or structure, although n-i-p configuration shows a wider range of linearity to the energy, p-i-n configuration is more suitable in the viewpoint of linearity and signal value for the considering energy range.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.11
• /
• pp.1650-1658
• /
• 2001

An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the fractional collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using highly monodisperse particles ranging from 0.02 to 0.6 $\mu\textrm{m}$ in diameter at three different charging states: singly charged, uncharged, and equilibrium charged. The face velocity was varied from 2.4 to 20.4 crus. It was fecund that the fractional efficiency curve fur singly charged particles shows a typical trend that the collection efficiency is minimum at about 0.3 $\mu\textrm{m}$ in diameter. The fractional efficiency of equilibrium charged particles were not severely varied with the particle diameter. The collection efficiency curve fur uncharged particles has a minimum near 0.1 $\mu\textrm{m}$ in diameter. Another experiment was conducted for a cartridge filter to examine the effect of charge depletion on the collection efficiency in a cabin air filter. The result shows that the charge depletion of the cartridge filter can significantly lower the collection efficiency.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.7
• /
• pp.834-843
• /
• 2014

A two-stage electrostatic precipitator (ESP) using a carbon brush charger and a plate-plate parallel aluminum collector was developed and its application for removal of oil mist aerosols was investigated. Charge number per particle and particle collection efficiency at different applied voltage to the carbon brush charger were measured and compared to those obtained by theoretical calculations. A long-term operation of the ESP during 9 weeks was also performed to evaluate its performance durability for oil mists. Average charge number per mist particle increased with the applied voltage to the charger, and thus the collection efficiency of the mist particles also increased overall at the particle size range of 0.26 - 3 mm. The tendencies of the average charge number per particle and particle collection efficiency obtained from theoretical calculations were considerably consistent with those of the experimental results. Particle collection efficiency of ~99 % at 0.3 mm could be achieved by power consumption of only 0.0033 W/($m^3/h$) at the face velocity of 1 m/s and its collection performance maintained stably during every 8 hr operation per day for 9 weeks with little increase of pressure drop.

• International Commerce and Information Review
• /
• v.10 no.4
• /
• pp.513-532
• /
• 2008

The purpose of this study was to analyze which factors have had impacts on extension export insurance charge of Korean export insurance. In order to attainment of this study, an empirical study was proceeded. The export insurance charge was hired as the dependent variable and export insurance premium, insurance compensation charge, export insurance collection charge and export insurance fund were used as independent variables. Data was used for estimation are the annually data from 1969 to 2007. From results of this analysis, we find the hired variables have highly correlation among them and the most influential factor turns out to be export insurance fund. Main results of this study was as follows : i) The export insurance fund must be increased immediately. ii) It is necessary that Korea Export Insurance Corporation give their attention to the compensate amount of export insurance compensation on specific insurance item. iii) It is necessary that Korea Export Insurance Corporation extension the collection efforts of the export insurance. iv) A reasonable raising of export insurance premium need to be done.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.1
• /
• pp.83-89
• /
• 1999

A Unified model for the alpha-particle-induced charge collection has been developed. By accounting for funneling and diffusion charges separately, new model accurately describes the dependence of collected charge on junction size, junction bias, injection energy, injection angle, injection point, and trench oxide depth.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.97-103
• /
• 2001

The effects of the electrohydrodynamic (EHD) flow and turbulent diffusion on the collection efficiency of a model ESP composed of the plates with a cavity were studied through numerical computation. The electric field and ion space charge density were calculated by the Poisson equation of the electrical potential and the current continuity equation. The EHD flow field was solved by the continuity and momentum equations of the gas phase including the electrical body force induced by the movement of ions under the electric field. The RNG $k-{\varepsilon}$ model was used to analyze the turbulent flow. The particle concentration distribution was calculated from the convective diffusion equation of the particle phase. As the ion space charge increased, the particulate collection efficiency increased because the electrical potential increased over the entire domain in the ESP. The collection efficiency decreased and then increased, i.e. had a minimum value, as the EHD circulating flow became stronger when the electrical migration velocity of the charged particle was low. However, the collection efficiency decreased with the stronger EHD flow when the electrical migration of the particle was higher relatively. The collection efficiency of the model ESP increased as the turbulent diffusivity of the particle increased when the electrical migration velocity of the particle was low. However, the collection efficiency decreased for increasing the turbulent diffusivity when the electrical migration of the particle was higher relatively.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.8
• /
• pp.598-605
• /
• 2011

The main object of this study is to investigate the Dust Collection Characteristics of multi-layer multi-stage porous plate system with polarization charging mechanism, experimentally. The experiment is carried to analyze the characteristics of pressure drop and collection efficiency for the present system with the experimental parameters such as applied voltage, inlet velocity, inlet concentration and stage number, etc. In results, the pressure drop becomes 18 to $134mmH_2O$, with increment of stage number (1 to 5) at inlet velocity $v_{in}$ = 3.11 m/s ($v_t$ = 18 m/s) and inlet concentration 3 g/m3 for inflow current. In case of both applied voltage 0 kV and non-inflow current, the collection efficiency of 5 stage is 92.5% at $v_{in}$ = 2.58 m/s ($v_t$ = 15 m/s), while it is estimated that the collection efficiency becomes about 6% higher than that of 0 kV and non-inflow as 98.5% at $v_{in}$ = 2.58 m/s for both alternating polarization charge (applied voltage 2.5 kV) and inflow current system.

• Journal of Radiation Protection and Research
• /
• v.30 no.2
• /
• pp.69-75
• /
• 2005

Gas avalanche microdetectors, such as micro-strip gas chamber (MSGC), micro-gap chamber (MGC), micro-dot chamber (MDOT), etc., are operated under high voltage to induce large electron avalanche signal around micro-size anodes. Therefore, the anodes are highly exposed to electrical damage, for example, sparking because of the interaction between high electric field strength and charge multiplication around the anodes. Gas electron multiplier (GEM) is a charge preamplifying device in which charge multiplication can be confined, so that it makes that the charge multiplication region can be separate from the readout micro-anodes in 9as avalanche microdetectors possible. Primary electron collection efficiency is an important measure for the GEM performance. We have defined that the primary electron collection efficiency is the fractional number of electron trajectories reaching to the collection plane from the drift plane through the GEM holes. The electron trajectories were estimated based on 3-dimensional (3D) finite element method (FEM). In this paper, we present the primary electron collection efficiency with respect to various GEM operation parameters. This simulation work will be very useful for the better design of the GEM.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.1
• /
• pp.82-90
• /
• 1998

The study was carried out to investigate on the response of environmental sanitation problems in action of the volume based waste charge system in Seoul. The responses from the 396 persons who dwelled in Seoul was stimulatively answered, this system was considered as a successful one 69.6% of total answers, but little portion (21.2%) of those was unknown on the mean of this system. And we knew that this system was need to the communication and education through the press media about this one. After the action of the volume based waste charge system, the volume of refuse discharged in a day was decreased 30-50% than before. In the problems of environmental sanitation after this system, the number of sanitary insect(cockroach etc) and rat was decreased, also the production of order and dust caused by refuse was decreased in comparison with those before. This results were considered that the Separate Collection should be perfectly performed. In response, the regular envelope of refuge was serious problems, the improvement for this one was demanded, The kind of difficult refuse treated was waste foodstuffs> electric products> rubbers> furniture> bottles, cans>papers, pulps etc. and the next proposal for this system should be prepared. Conclusively, the volume based waste charge system should be remarkable system in terms of resources recycling as well as wastes reduction. Above all in order to conform this system the separate collection system should be systematically performed, the next improvable proposal of the detailed methods in this system should be prepared.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.11
• /
• pp.1509-1517
• /
• 1997

Charged and uncharged particle motions and collection characteristics around a bipolar charged rectangular shape electret fiber are studied numerically. Particle inertia, fluid drag, Coulomb force and polarization force are considered to predict the particle motion around the electret fiber. The effects of particle sizes, flow velocities, number of charges and polarities are also systematically investigated. For small size particles, the single fiber collection efficiency is greatly dependent on the charge polarity and the number of charges on a particle. However, particles larger than 5.mu.m do not show charging effect on collection efficiencies in the flow velocity ranges from 1.5 cm/s to 150 cm/s when the maximum charges are within +5 to -10. The results show that a strong electric field gradient at the corner of the bipolar charged fiber plays a very important role on collecting particles regardless of its charge polarity because of the polarization force. It also shows that the most penetrating particle size for a single electret fiber decreases as the flow velocity increases and the number of charges of a particle decreases.