• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.119.2-119.2
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• 2012

Charged particle energization is an outstanding problem in space physics. This paper investigates the nonlinear dynamics of Alfve'n-cyclotron waves accompanying particle heating processes and the drift Alfv'en-cyclotron (or EMIC) instability associated with a current disruption event on 29 January 2008 observed with THEMIS satellite by means of a particle-in-cell simulation. The simulation shows that the drift Alfv'en-cyclotron instabilities are excited in two regimes, a relatively low frequency mode propagating in a quasi-perpendicular direction while the second high-frequency branch propagating in a predominantly parallel propagation direction, which is consistent with observation as well as earlier theories. It is shown that parametric decay processes lead to an inverse cascade of Alfv'en-cyclotron waves and the generation of ion-acoustic waves by decay instability. It is also shown that the nonlinear decay processes are accompanied by small perpendicular heating and parallel cooling of the protons, and a pronounced parallel heating of the electrons.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.33.3-34
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• 2008

As an activity of building Korean Space Weather Prediction Center (KSWPC), we has studied of radiation effect on the spacecraft components. High energy charged particles trapped by geomagnetic field in the region named Van Allen Belt can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-1) was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-1 orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-1 solar cell degradation was caused by energetic protons which energy is about 700 keV to 1.5 MeV. Our result can be applied to estimate solar cell conditions of other satellites.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.65-71
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• 2016

In this study, Antimony Tin Oxide (ATO) ion storage layer and $TiO_2$ working electrode were fabricated using Nano Particle Deposition System. NPDS is the cutting-edge technology among the dry deposition methods. Accelerated particles are deposited on the substrate through the nozzle using NPDS. The thicknesses for coated layers were measured and layer's morphology was acquired using SEM. The fabricated electrochromic cell's transmittance was measured using UV-Visible spectrometer and power source at 630 nm. As a result, the integrated electrochromic/DSSC hybrid system was successfully fabricated as an energy harvesting system. The fabricated electrochromic cell was self-operated using DSSC as a power source. In conclusion, the electrochromic cell was operated for 500 cycles, with 49% of maximum transmittance change. Also the photovoltaic efficiency for DSSC was measured to be 2.55% while the electrochromic cell on the integrated system had resulted in 26% of maximum transmittance change.

• Journal of Plant Biology
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• v.37 no.1
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• pp.27-36
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• 1994

For establishing a transformation system of rice, an efficient introduction of foreign genes into embryogenic cell suspension by particle bombardment was conducted. The particle inflow gun based on the acceleration of DNA-coated tungsten particles using pressurized helium was constructed for delivery of DNA into rice cells. Several bombardment parameters were optimized using the transient expression of GUS gene. The conditions that gave the highest GUS gene expression of about 1000 blue spots per g fresh weight of bombarded cells include treatment of the cells with 0.5 M osmotic pressure, and use of the 410 kPa helium, 110 mm target distance, 13 mm syringe filter holder and 5 $\mu$L DNA/tungsten mixtures. It was also confirmed that rice actin promoter-intron construct gave the highest expression of all promoter-sequences studied. Eight weeks after the bombardment, stably transformed calluses were obtained on the selection medium containing 100 mg/L G418 and showed the strong activity in in situ GUS assay.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.503-512
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• 2012

There is a new power generation system such as direct coal fuel cell (DCFC) with a solid oxide electrolyte operated at relatively high temperature. In the system, it is of great importance to feed coal continuously into anodic electrode surface for its better contact, otherwise it would reduce electrochemical conversion of coal. For that purpose, it is required to improve the electrochemical conversion efficiency by using either rigorous mixing condition such as fluidized bed condition or just by recirculating coal particle itself successively into the reaction zone of the system. In this preliminary study, we followed the second approach to investigate how significantly particle recycle would affect the coal conversion efficiency. As a first phase, coal conversion was analyzed and evaluated from the thermochemical reaction of carbon with air under particle recirculating condition. The coal conversion efficiency was obtained from raw data measured by two different techniques. Effects of temperature and fuel properties on the coal conversion are specifically examined from the thermochemical reaction.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.213-219
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• 2002

The CellCaSi, a porous silicate material, was tested for the removal of phosphorus (P as phosphate) in water. The effect of the CellCaSi was investigated on the basis of both particle size (under 1,2, and 4 mm) and added amount (0, 1, 2.5, 5, and 10 g/1) of the CellCaSi. The removal efficiency of phosphorus was highest with a particle size of under 1 mm and also increased with an increasing amount of the CellCaSi. The pH change showed little effect on the phosphorus removal of the CellCaSi. The calcium ion was eluted from the CellCaSi into the water, while the aluminium and iron were not. The eluted calcium ion was combined with dissolved phosphorus and then precipitated. The highest removal efficiency of phosphorus was obtained by the combined addition of the CellCaSi, calcium chloride, and ferric chloride. That is, the phosphorus concentrations of 0.10 and 1.0 mg/1 decreased to 0.03 and 0.47 mg/l by the addition of the CellCaSi (1 g/l), calcium ion (30 mg/l), and ferric ion (1 mg/l) at day 8 after treatment. The water qualities at the end of the experiment were as follows: pH was 8.1 and conductivity was 318 ${\mu}$S/cm (a registered maximum conductivity of 500${\mu}$S/cm for raw and potable wafers).

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.157-162
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• 2012

In this study, we have for the first time applied increased surface area fractional precipitation in order to decrease the particle size of the anticancer agent paclitaxel from plant cell cultures. When compared with the case where no surface area increasing material was employed, the addition of ion exchange resin as a surface area increasing material resulted in a considerable decrease in the size of the paclitaxel precipitate. When ion exchange resin was used, the paclitaxel particles were four to five times smaller, having less than a 20 ${\mu}m$ radius, than those obtained in the absence of ion exchange resin. This is presumably because the growth of paclitaxel particles was impeded by the addition of ion exchange resin. The size of the paclitaxel precipitate also depended on the material used to increase the surface area, a result considered to be due to differences in the affinity between the particular ion exchange resin used and the paclitaxel particles. The yield of paclitaxel was significantly improved when ion exchange resin was used as a material to increase surface area. Paclitaxel, with a reduced particle size due to the addition of a surface area increasing material during the fractional precipitation process, is believed to be particularly useful for practical applications of the drug.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.442-443
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• 2009

We prepared and characterized particle based CIGS thin film using a thermal evaporator. CIGS powder were obtained at $240^{\circ}C$ for 6 hours from the reaction of $CuCl_2$, $InCl_3$, $GaCl_3$, Se powder in solvent. The CIGS thin film deposited on a sodalime glass. The CIGS thin film were identified to have a typical chalcopyrite tetragonal structure by using UV/Vis-spectroscopy, X-ray diffraction(XRD), Auger Electron Spectroscopy(AES), Scanning Electron Microscopy(SEM).

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.323-325
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• 2004

To model the behavior of expanded beds with aqueous feed streams containing different amounts of glycerol, we previously developed a modified Stokes expression that correlates the terminal settling velocity of a particle of a solution with the properties of the particle (particle diameter and density) and the solution (density and viscosity). Two empirical parameters, the effective diameter of the poly-disperse resins for protein adsorption and an exponent of non-unity for $(\rho_{P}-\rho)/\mu$ term, are introduced in the modified Stokes expression. We applied the same type of the modified Stokes expression in combination with the Richardson-Zaki correlation to the published results [1], and found that the expansions of the beds with feed streams containing different amounts of E. coli homogenates can also be successfully described.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.271-276
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• 2006

Insight into behaviour of pedestrians as welt as tools to assess passenger flow condition is important in such instances as planning and geometric design of railway station under regular and safety-critical circumstances. Algorithm for passenger flow analysis based on DEM (Discrete Element Method) is newly developed. There are lots of similarity between particle-laden two phase flow and passenger flow. The velocity component of 1st phase corresponds to the unit vector of calculation cell, each particle to passenger, volume fraction to population density and the particle velocity to the walking velocity, etc. And, the walking velocity of passenger is also represented by the function of population density. Key algorithms are developed to determine the position of passenger, population density and numbering to each passenger. To verify the effectiveness of new algorithm, passenger flow analysis for the basic models of railway station is conducted.