• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.5
• /
• pp.492-497
• /
• 2006

The study on laser-ablation plasmas has been strongly interested in fundamental aspects of laser-solid interaction and consequent plasma generation. In particular, this plasma has been widely used for the deposition of thin solid films and applied to the semiconductors and insulators. In this paper, we developed and discussed the generation of carbon ablation plasmas emitted by laser radiation on a solid target, graphite. The progress of carbon plasmas by laser-ablation was simulated using Monte-Carlo particle model under the pressures of vacuum, 1 Pa, 10 Pa and 66 Pa. At the results, carbon particles with low energy were deposited on the substrate as the pressure becomes higher However, there was no difference of deposition distributions of carbon particles on the substrate regardless of the pressure.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.434-434
• /
• 2011

Electrochemical method have been employed in this work to modify the chemical vapour deposited nitrogen doped hydrogen amorphous diamond-like carbon (N-DLC) film to fabricate nickel and copper nano particle modified N-DLC electrodes. The electrochemical behaviour of the metal nano particle modified N-DLC electrodes have been characterized at the presence of glucose in electrolyte. Meanwhile, the N-DLC film structure and the morphology of metal nano particles on the N-DLC surface have been investigated using micro-Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The nickel nano particle modified N-DLC electrode exhibits a high catalytic activity and low background current, while the advantage of copper modified N-DLC electrode is drawn back by copper oxidizations at anodic potentials. The results show that metal nano particle modification of N-DLC surface could be a promising method for controlling the electrochemical properties of N-DLC electrodes.

• Journal of Korean Society for Atmospheric Environment
• /
• v.12 no.4
• /
• pp.377-387
• /
• 1996

This study was carried out to monitor the visibility including measurement and analysis of the various parameters such as particle size distribution, chemical composition, and meteorotical conditions to understand the characteristics and causes of this phenomenon. According to the analysis of intensive sampling, $SO_4^{2-}, NO-3^-, Cl^-, NH_4^+$ ion concentration increased together with the mass concentration around 1 $\mu$m in the case of low visibility. $(NH_4)_2SO_4, NH_4NO_3$, and $NH_4Cl$ were thought to be the major components of fine particles. The statistical analysis showed that the scattering effect of particle was 81.2%, the absorption effect was 14.9%. Therefore, these effects were the major factors to reduce the visibility. In conclusion, the visibility was reduced by the fine particle of sulfate (18.6%), nitrate (14.2%), organic carbon (10.8%), element carbon (25.8%), and residual (24.8%) during this study.

• Particle and aerosol research
• /
• v.4 no.2
• /
• pp.51-67
• /
• 2008

In this study, we devoted to kinetic measurement of the catalytic oxidation of iron-containing flame soot particles and better understanding the role of catalytic particles on carbon oxidation in particular at low temperature, targeting on autothermal regeneration of diesel particulate filter by diesel exhaust gas. Carbon-based Fe-containing particles generated by spraying ferrocene-doped diesel fuel in an oxy-hydrogen flame are tested and compared with a commercial carbon black powder for thermogravimetric analysis (TGA), secondary ion mass spectrometry (SIMS), Fourier-transform infrared spectroscopy (FTIR), Induced coupled plasma-Atomic emission spectroscopy (ICP-AES), and High-resolution transmission electron microscopy (HR-TEM). As a result, we found that a small amount of the ferrocene addition led to significant reductions in a on-set temperature and an activation energy of the carbon oxidation as well. An oxygenated surface complex forming at the particle surface could be thought as active species that would be readily consumed in particular at low temperature.

• Journal of the Korean Ceramic Society
• /
• v.40 no.3
• /
• pp.219-224
• /
• 2003

Fly ashes containing 6.1~16.5 wt% of unburned carbon were treated thermally at 500$^{\circ}C$ for 3 h and thus, the content of unburned carbon was decreased below 2.1 wt%, the range of particle size distribution became narrower and the mean particle size became smaller. Besides, the properties of particles in fly ashes were improved, particularly the particle shape became close to a spherical type. The fluidity of cement pastes containing fly ashes treated previously at 500$^{\circ}C$ for 3 h was increased much than that of cement pastes containing original fly ashes. When the added amount of superplasticizer was over the saturation amount, there was no correlation between the amount of unburned carbon in fly ashes and the apparent viscosity of cement pastes actually. On the contrary, when the added amount of superplasticizer was below the saturation amount, there was a correlation.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.195-196
• /
• 2021

The pore distribution of the cement mortar mixed with carbon nanotubes was found to have a large number of pores at (370~80)㎛, and the distribution ratio was larger as the carbon nanotubes were mixed. However, the pores with a fine particle diameter of (10-0.5) ㎛ were found to be larger as the carbon nanotubes were incorporated. However, the distribution of pores of the test specimens of conductive cement mortar with deterioration damage was found to be distributed in a number of particle diameters of (500 to 100) ㎛ and (10 to 0.5) ㎛. It is judged that the particle diameter of the internal pores increased due to the damage. However, as the mixing ratio of the test specimen with carbon nanotubes increased, the distribution of voids was relatively lower than that of plain, and it was judged to have excellent resistance to deterioration damage.

• 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.

• Journal of Power System Engineering
• /
• v.17 no.6
• /
• pp.115-121
• /
• 2013

This study was carried out to investigate the effect of hot forging on the hardness and impact value of ultra high carbon low alloy steel. With increasing hot forging ratio, thickness of the network and acicular proeutectoid cementite decreased, and than were broken up into particle shapes, when the forging ratio was 80%, the network and acicular shape of the as-cast state disappeared. Interlamellar spacing and the thickness of eutectoid cementite decreased with increasing forging ratio, and were broken up into particle shapes, which then became spheroidized. With increasing hot forging ratio, hardness, tensile strength, elongation and impact value were not changed up 50%, and then hardness rapidly decreased, while impact value rapidly increased. Hardness and impact value was greatly affected by the disappeared of network and acicular shape of proeutectoid cementite, and became particle shape than thickness reduction of proeutectoid and eutectoid cementite.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.16 no.1
• /
• pp.39-53
• /
• 1998

The extraction rate of ginger from Korean-grown ginger root with supercritical carbon dioxide was measured as a function of flow rate of supercritical carbon dioxide, particle size, temperature and pressure. the extraction rate increased as the particle size decreased due to a decrease in the diffusion path. The extraction rate were independent of flow rate of supercritical carbon dioxide in a plot of ginger oil yield versus extraction time. This indicated that the extraction process is controlled by intraparticle diffusion within a particle of ginger root. In the case of temperature and pressure effect, the experimental results showed that the extraction rate decreased with an increase in temperature and increased with an increase in pressure.

• 한국연소학회:학술대회논문집
• /
• 1999.10a
• /
• pp.139-148
• /
• 1999

In oder to analyze the effect of operating conditions on pulverized coal combustion, a numerical study is conducted at the pulverized coal combustor. Eulerian approach is used for the gas phase, whereas Lagrangian approach is used for the particle phase. Turbulence is modeled using standard ${\kappa}-{\varepsilon}$ model. The description of species transport and combustion chemistry is based on the mixture fraction/probability density function(PDF) approach. Radiation is modeled using P-l model. The turbulent dispersion of particles is modeled using discrete random walk model. Swirl number of secondary air affects the flame front, particle residence time and carbon conversion. Primary/Secondary air mass ratio also affects the flame front but little affects the carbon conversion and particle residence time. Air-fuel ratio only affects the flame front due to lack of oxygen. Radiation strongly affects the flame front and gas temperature distribution because pulverized coal flame of high temperature is considered.