• Journal of environmental and Sanitary engineering
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• v.17 no.2
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• pp.11-17
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• 2002

Diesel particulate matter (DPM) is known to be one of the major harmful emissions produced by diesel engines. The majority of diesel particles are in the range of smaller than $I{\mu}\textrm{m}$. Because of their tiny volume, ultrafine diesel particles contribute very little to the total mass concentration which is currently regulated for automobile emissions. Diesel particles are known to have deleterious effects upon human health because they penetrate human respiratory tract and have negative effects on the health. The measurement of the number distribution of nanometer size particles (nanoparticles) in the diesel exhaust emission is important in order to evaluate their environmental and health impact, and to develop new types of diesel particulate filters. In this study, we directly sampled particulate matters emitted from a diesel truck mounted on the chassis dynamometer by a flow separator and dilution system, and measured the nanoparticles using two types of differential mobility analyzers combined with a Faraday cup electrometer (FCE) and a condensation particle counter (CPC). The particle size distributions were analyzed by changing engine operation condition, i.e. ratio of engine loading. The total number concentration of particles were increased with the engine loading ratio and the nanoparticles (less than 50nm) were affected by hydrocarbon (HC) concentration in the diesel exhaust.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.91-96
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• 2003

This study was intended as an investigation of characteristics of background site atmospheric respirable particulate matters(RPM), and fine particles(<2.5 ${\mu}{\textrm}{m}$). The particle size distributions during the phenomenon of Yellow Sand(YS) occurs from April, 2001. Atmospheric aerosol particulate matter was directly collected on the Jeju island between 1 to 30, April, 2001 using an eight-stage cascade impacter(particle size range: 0.43-11 ${\mu}{\textrm}{m}$), and cyclone separator(cut size: 2.5, 10 ${\mu}{\textrm}{m}$). The episode of YS observed in background monitoring site, Kosan and appeared 2 times at sampling period. The mass concentrations of fine and coarse particles for YS episode were 34.2 and 59.6 $\mu\textrm{g}$/㎥, respectively, which were significantly increased amounts compared to 13.3 and 13.0 $\mu\textrm{g}$/㎥ for NonYS(NYS). Most size distributions had two peaks, one at 0.43∼.65 ${\mu}{\textrm}{m}$ and the other at 3.3${\mu}{\textrm}{m}$4.7 ${\mu}{\textrm}{m}$. The result of analysis of water-soluble ion component indicated that sulfate was mainly ion component, but nitrate and calcium ion was significantly increased at the YS episode.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.87-91
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• 2009

This study investigates possibility for practical use through small sized test with OPC and substituted fly ash 10% and return coarse cement (RCC), classed 1100${\sim}$1200 cm2/g, which is made by Cyclone Separator at cement producing process 20% (CF) for OPC. The experimental factors are 48% of W/B and OPC and 2 kinds of concrete proportions. The target slump and air content are $150{\pm}25$ mm and $4.5{\pm}1.5$ %. For the results, the flowalility and air content of CF are less than OPC because it needs more superplasticiser and air-entraining agent. The temperature history of CF is lower than OPC about $6{\sim}10^{\circ}C$. For the strength properties, CF is less than OPC, but their gap is declined at 28 days. The strength of the specimens are ordered by standard curing, field cured specimens, and core specimens.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.4
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• pp.288-295
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• 2014

This study was conducted to evaluate the effect of mixing time for TMR (total mixed rations) mixed with corn silage on particle size, peNDF (physically effective neutral detergent fiber), laceration, and ruminal in situ dry matter degradation. The study also aimed to evaluate the effect of consumption of the TMR on the milk yield and milk components of mid-lactational dairy cows. TMRs were mixed for 30 minutes (T1) and 50 minutes (T2) using the same material. All samples were then analyzed with a Penn State Particle Size Separator (PSPS). The particle size of T1 was significantly lower in the bottom pan (8 mm>) than that of T2 (p<0.01). $peNDF_{&gt;8.0}$ was significantly higher in T1 (17.18%) than in T2 (13.85%) (p<0.01). For ruminal in situ dry matter degradation of particle retention (>19 mm), no significant difference was found after 72 hours incubation, although T1 degradation was significantly higher after 24 hours incubation (p<0.01). Milk yield was no different between the groups of cows, whereas the milk fat from T1 fed cows was significantly higher (p<0.01). The results show that feeding TMR mixed for 30 minutes to dairy cows may improve the physical value of forage without negative effects on the milk yield and milk components.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.153-158
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• 2000

Flow visualization and PIV measurements were conducted to investigate the flow characteristics of multi-channel with inclination angle. The water flow seeded with tiny vegetable powder as tracers revealed details of flow field. The PIV measurement to acquire multi-point velocity data simulatneously was carried out at three space of plates for 5, 10, and 15mm with variation of inlet flow rates of $0.25m^3/h$ and <$0.5m^3/h.$ Experiment results show that space of plates acts a significant role in separating process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.97-105
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• 1998

The goal of this study is to investigate the potential application of triboelectrostatic separation process for removing unburned carbon from fly ash. The process utilizes the difference in electrical charging characteristics between the organic material (carbon) and the mineral matter (fly ash). In the present work, dry separation tests have been conducted on Samchunpo fly ash samples using a bench - scale analytic separator. The test variables studied include air rate, feed rate, electric field strength, particle size, charger material and length, etc. The best separation results were obtained at the air rate 501/min, feed rate 15 g/min and voltage 15 ㎸. The fly ash with carbon content below 1 % was obtained with over 65% recovery.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.425-427
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• 1994

A manipulator which can separate dielectric particles (biological cells) was fabricated on a silicon wafer using polyimide and n-type electroplating. It consists of 1024 electrode arrays ($60{\mu}m{\times}60{\mu}m$) and spacing insulator. Positive dielectrophoresis is used for attracting particles. We have the solution of 3-D laplace equation about this device and calculate the force acting on the particles. The solution has spatial periodicity in the x, y directions and decays exponentially in the z direction.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.293-298
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• 2016

A hydrogel electrolyte consisting of 6 M KOH aqueous solution, potassium polyacrylate (PAAK, 3 wt.%), and a hydrophilic silica OX50 (1 wt.%) was prepared to use as an electrolyte medium coated on a Scimat separator of activated carbon supercapacitor. The silica particle distributed homogeneously on surface pores of the separator to increase ionic conductivity and electrochemical stability of the hydrogel electrolyte. The silica addition also involved superior specific capacitance even at higher scan rates due to decrease in interfacial resistance between hydrogel electrolyte and activated carbon electrode.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.355-361
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• 2009

Effects of operating variables on solid separation rate in two-interconnected fluidized beds system for selective solid circulation have been investigated. Coarse(212~300 or $425{\sim}600{\mu}m$) and fine($63{\sim}106{\mu}m$) particles were separated using the solid separator and the solid separation rate was ranged from 66 to 987 g/min. The solid separation rate increased as the gas velocity through the solid injection nozzle, solid height, diameter of solid injection nozzle, particle size of coarse particles, aperture of the solid separator, and weight fraction of fines in the solid mixture increased. However, the effect of the fluidization velocity was negligible.

• Journal of Powder Materials
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• v.24 no.5
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• pp.364-369
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• 2017

Ceramic powder, such as MgO, is added as a binder to prepare the green compacts of molten salts of an electrolyte for a thermal battery. Despite the addition of a binder, when the thickness of the electrolyte decreases to improve the battery performance, the problem with the unintentional short circuit between the anode and cathode still remains. To improve the current powder molding method, a new type of electrolyte separator with porous MgO preforms is prepared and characteristics of the thermal battery are evaluated. A Spherical PMMA polymer powder is added as a pore-forming agent in the MgO powder, and an organic binder is used to prepare slurry appropriate for tape casting. A porous MgO preform with $300{\mu}m$ thickness is prepared through a binder burnout and sintering process. The particle size of the starting MgO powder has an effect, not on the porosity of the porous MgO preform, but on the battery characteristics. The porosity of the porous MgO preforms is controlled from 60 to 75% using a pore-forming agent. The batteries prepared using various porosities of preforms show a performance equal to or higher than that of the pellet-shaped battery prepared by the conventional powder molding method.