• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E2
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• pp.61-68
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• 2004

Aerosol losses in a 100L Tedlar$^{(R)}$ bag were investigated for the aerosols with number median diameter of 0.05 ${\mu}{\textrm}{m}$ and number concentration of 6.4 ${\times}$ 10$^4$ cm$^{-3}$ . Over a 1 hr period, loss of particles in the bag is apparent, and the volume decrease with time is significant. The number concentration, surface area, and volume concentration of the aerosols decreased to 34, 50, and 52% of the initial value in 30 min, respectively. This indicates that deposition to the walls was the main loss process for aerosols in the Tedlar$^{(R)}$ bag. Theoretical calculations showed that coagulations and deposition by diffusion and gravitational sedimentation would not change aerosol characteristics significantly, and the electrical force was the dominant loss process for particles in the Tedlar$^{(R)}$ bag over a 1 hr period.eriod.

• Particle and aerosol research
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• v.13 no.4
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• pp.165-172
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• 2017

For precise particle measurements in combustion environments, various dilution sampling methods were compared. Dilution equipments using dilution tunnels and hot/cold dilution with porous tube dilutors were most frequently used so far. The combination of porous tube dilutor and ejector diluter has relatively small footprint, and it results in lower particle losses compared to other methods. To determine the portion of condensable particulate matter, proper temperature control and flow control is required.

• Particle and aerosol research
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• v.19 no.2
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• pp.21-30
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• 2023

Solar cells, converting abundant solar energy into electrical energy, are considered crucial for sustainable energy generation. Recent advancements focus on nanoparticle-enhanced solar cells to overcome limitations and improve efficiency. These cells offer two potential efficiency enhancements. Firstly, plasmonic effects through nanoparticles can improve optical performance by enhancing absorption. Secondly, nanoparticles can improve charge transport and reduce recombination losses, enhancing electrical performance. However, factors like nanoparticle size, placement, and solar cell structure influence the overall performance. This study evaluates the performance of silver nanoparticles incorporated in a p-i-n structure of perovskite solar cells, generated via aerosol state by the evaporation and condensation system. The silver nanoparticles deposited between the hole transport layer and transparent electrode form nanoparticle embedded transport layer (NETL). The evaluation of the optoelectronic properties of perovskite devices using NETL demonstrates their potential for improving efficiency. The findings highlight the possibility of nanoparticle incorporation in perovskite solar cells, providing insights for sustainable energy generation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.237-238
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• 2002

Particle - bound water changes the physical and chemical properties of aerosol particles, such as size and light scattering properties. Consequently, it is necessary to remove water vapor from ambient aerosols before aerosol particles are sized and counted. Silicon gel diffusion dryer is commonly employed for this purpose. However, it can not be operated continuously While in operation, silicon gel becomes progressively more loaded with water and must periodically be regenerated by drying off the water. (omitted)

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.14-18
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• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.

• Particle and aerosol research
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• v.7 no.4
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• pp.123-130
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• 2011

Previous designs of conventional aerodynamic lenses have a limitation of narrow range of focusable particle size, e.g. 30 to 300nm or 3 to 30nm. To enlarge the focusable size range to 30-3000nm, it is necessary to avoid a significant loss of particles larger than 300nm inside the lenses. From numerical simulations on size-resolved particle trajectories, we confirmed that the traveling losses of such large particles could be avoided only when the radial position of particles approaching the orifice lens was near the lens axis. Hence, we designed the lens system consisting of a converging-diverging nozzle and 7 orifices to fulfill the requirement. In particular, the orifices were aligned in a way that their diameters were descending and ascending to the downstream. As a result, 30-2800nm particles can be focused to the particle beam of 0.2mm or less in radius with above 85% transmission efficiency. Even $10{\mu}m$ particles can be focused with 74% of transmission efficiency.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2021-2030
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• 2017

In this paper, the unipolar corona-needle charger was developed and its capabilities were both numerically and experimentally investigated. The experimental corona discharges and particle losses in the charger were obtained at different corona voltage, aerosol flow rate and particle diameter for positive and negative coronas. Inside the charger, the electric field and charge distribution and the transport behavior of the charged particle were predicted by a numerical simulation. The experimental results yielded the highest ion number concentrations of about $1.087{\times}10^{15}ions/m^3$ for a positive corona voltage of about 3.2 kV, and $1.247{\times}10^{16}ions/m^3$ for a negative corona voltage of about 2.9 kV, and the highest $N_it$ product for positive and negative coronas was found to about $7.53{\times}10^{13}$ and $8.65{\times}10^{14}ions/m^3$ s was occurred at the positive and negative corona voltages of about 3.2 and 2.9 kV, respectively, and the flow rate of 0.3 L/min. The highest diffusion loss was found to occur at particles with diameter of 30 nm to be about 62.50 and 19.33 % for the aerosol flow rate of 0.3 and 1.5 L/min, respectively, and the highest electrostatic loss was found to occur at particles with diameters of 75 and 50 nm to be about 86.29 and 72.92 % for positive and negative corona voltages of about 2.9 and 2.5 kV, respectively. The numerical results for the electric field distribution and the charged particles migration inside the charger were used to guide the description of the electric field and the behavior of charged particle trajectories to improve the design and refinement of a unipolar corona-needle charger that otherwise could not be seen from the experimental data.

• Korean Journal of Veterinary Research
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• v.46 no.3
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• pp.207-214
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• 2006

Mycoplasma gallisepticum (MG) continues to persist in many commercial layer farms in Korea,resulting in losses in egg production. Bacterins and live attenuated vaccines have been used for the prevention of losses caused by MG. One of these attenuated vaccines, MG 6/85 vaccine has been reported to be safe and efficacious in layers. However, MG 6/85 vaccine has not been evaluated for its safety and its efficacy in any commercial layer in Korea. Six-week-old specific pathogen-free (SPF) chickens were vaccinated with MG 6/85 vaccine by aerosol and were challenged with virulent MG R strain at 4 weeks after vaccination. The vaccinated group was able to resist challenge into the air sacs because the vaccinated group showed much less air sac lesion compared with the unvaccinated group. Each of two commercial layer farms was divided into vaccinated and unvaccinated groups. For each vaccinated gorup, MG 6/85 vaccine were sprayed at 17 week old on farm A and at 15 weeks old on farm B. Hen-day egg production, Hen-housed eggs, egg weight, mortality were evaluated until 50 week after vaccination.Compared with the unvaccinated group in each farm, the vaccinated group showed higher average egg production and egg weight, and higher hen-housed number. Results of this study are in agreement with other previous reports which demonstrated that MG 6/85 vaccine favorable effect on performance in commercial layers.

• Journal of the Korean earth science society
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• v.40 no.3
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• pp.240-258
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• 2019

Typhoons, torrential rainfall, and heavy snowfall cause catastrophic losses each year in the Republic of Korea. Therefore, if we can know the possibility of this phenomenon in advance through regular observations, it will be greatly beneficial to Korean society. Korea is surrounded by sea on its three sides, and the sea surface temperature (SST) directly or indirectly affects the development of typhoons, heavy rainfall, and heavy snowfall. Therefore, the characteristics of SST variability related to the high impact weather are investigated in this paper. The heavy rainfall in Korea was distributed around Seoul, Gyeonggi, and west and southern coast. The heavy snowfall occurred mainly in the eastern coastal (hereafter Youngdong Heavy Snow) and the southwestern region (hereafter Honam-type heavy snow). The SST variability was slightly different depending on the type and major occurrence regions of the high impact weather. When the torrential rain occurred, the SST variability was significantly increased in the regions extending to Jindo-Jeju island-Ieodo-Shanghai in China. When the heavy snow occurred, the SST variability has reduced in the southern sea of Jeju island, regardless of the type of heavy snowfall, whereas the SST variability has increased in the East Sea near $130^{\circ}E$ and $39^{\circ}N$. Areas with high SST variability are anticipated to be used as a basis for studying the atmospheric-oceanic interaction mechanism as well as for determining the background atmospheric aerosol observation area.