• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.4 s.235
• /
• pp.453-459
• /
• 2005

In this paper, we are proposing a robust tool which is capable of measuring the size and elemental composition of submicron particles from twenty to several hundreds nanometers at the same time, i.e., named Single Particle Mass Spectrometer (SPMS). The home-made SPMS employs a laser ablation/multi-photon ionization method to tear a nanoparticle into the constituent elemental ions. One thing different from the conventional Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) is the power of the ionization laser. Much strong laser used in this work makes it possible to generate elemental ions rather than molecular ions from a nanoparticle. Also the use of high power laser may guarantee a complete ionization of a particle, which was confirmed by the existence of multiple charged ions. If a particle is evaporated/ionized completely and detected through electric field-free TOF tube without any loss, we can extract the original particle volume from the measured total ion numbers. Collecting a number of particles mass spectra, we get a database of size and elemental composition of nanoparticles, with which we may take a took into any kinds of chemical reaction occurring at nanoscale. Several issues related to size estimation by SPMS will be discussed.

• Korean Journal of Materials Research
• /
• v.24 no.1
• /
• pp.25-32
• /
• 2014

In this study, nano-sized cobalt oxide powder with an average particle size below 50 nm was prepared from a cobalt chloride solution by the spray pyrolysis process. The influences of reaction temperature on the properties of the generated powder were examined. The average particle size of the particles formed based on the spray pyrolysis process at a reaction temperature of $700^{\circ}C$ is roughly 20 nm. Moreover, most of these particles cannot appear with an independent type, thereby coexisting in a droplet type. When the reaction temperature increases to $800^{\circ}C$, the average particle size not only increases to roughly 40 nm but also shows a more dense structure while the ratio of particles which shows a polygonal form significantly increases. As the reaction temperature increases to $900^{\circ}C$, the distribution of the particles is from roughly 70 nm to 100 nm, while most of the particle surface is more intricately close and forms a polygonal shape. When the reaction temperature increases to $1000^{\circ}C$, the particle size distribution of the powder shows an existing form from 80 nm to at least 150 nm in an uneven form. As the reaction temperature increases, the XRD peak intensity gradually increases, yet the specific surface area gradually decreases.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.48 no.6
• /
• pp.59-67
• /
• 2006

Particles of soil are crushed when soil is compacted in the in-situ or lab. Among many factors that affect the crush of particles, compaction energy is a major factor. Because the crush of particles can change physical properties, the analysis of effect of compaction energy is very important. In this study, the fragmentation fractals were used for determining the change in grain size distribution and the effect due to change in grain size distribution was estimated. Compaction energy was increased by 50, 100, 200 and 300% based on the energy of standard A compaction test. As a result, grain size distribution curves were changed and fine particles increased as compaction energy were increased. Relative compaction were ranged between $93.38{\sim}107.67$. Fractal dimension of each site increased as compaction energy increased. Relative compaction is proportional to the fractal dimension but coefficients of permeability were in inverse proportional to the involution of fractal dimension.

• Transactions of Materials Processing
• /
• v.14 no.4 s.76
• /
• pp.351-359
• /
• 2005

The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheo-casting has been substituted for thixo-casting, because the rheo-casting can control the solid particles to globular and non-dendritic solid phase. In the rheo-casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling tests during the semi-solid die casting in 0.3, 0.4, 0.5 and 0, 6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMA soft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.664-667
• /
• 2004

The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheolory casting has been substituted for thixo casting, because the rheology casting can control the solid particles to globular and non-dendritic solid phase. In the rheology casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling during the semi-solid die casting in 0.3, 0.4, 0.5, 0,6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMAsoft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.4
• /
• pp.309-314
• /
• 2018

Size reduction is an important pre-processing operation for utilizing biomass as a sustainable resource in industrial-scale energy production and as a raw material for other industries. This work investigates the size reduction characteristics of air-dried Miscanthus sacchariflorus Goedae-Uksae 1 (Amur silver grass) via image processing and identifies the morphological characteristics of comminuted and screened M. sacchariflorus. At chopping lengths of 18, 40, 80, and 160 mm, 81%, 77%, 78%, and 76% of the particles, respectively, passed through a 4-mm sieve. Even a knife mill with a very small screen aperture (>1 mm) admitted over 10% of the particles. The average circularity and aspect ratio of the particles were <0.30 and >10, respectively. These results confirm that in all preparation modes, most M. sacchariflorus particles were needle-like in shape, irrespective of the type of preparation.

• Journal of Korean Society for Atmospheric Environment
• /
• v.33 no.4
• /
• pp.361-369
• /
• 2017

In this study, the characteristics of the dust emission according to the presence or absence of operation of the gas stove were analyzed by particle size analysis and density estimation while the mackerel was cooked while the fan was placed on the gas stove used in the home. The experiment was carried out using 20 mackerel of normal size at home. Commercially available canola oil was used as edible oil. In order to understand the characteristics such as particle size distribution of fine dust, light scattering measurement method which can be measured at intervals of several seconds was used. Particles generated by combustion of gas stove, particles formed by heating cooking oil, and particles generated by heating mackerel fish meat are judged to be nano size particles smaller than $1{\mu}m$. Therefore, it is necessary to use precise measurement method rather than the measurement method using the filter which is currently being measured in the measurement of the particles discharged from the fuel combustion or food cooking in the future. Analyzing the particle size and density of the dust emitted from the cooking stove is expected to contribute technically to the reduction of dust emissions from the cooking process of gas and fuel facilities at home and commercial facilities.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.11 no.2
• /
• pp.67-70
• /
• 2001

Nanosize $SiO_2$composite particles have been synthesized within reverse micelle via metal alkoxide hydrolysis and condensation. The size of the particles can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the microemulsion. The average size of synthesized particles was about in the size range 14~30nm. The effects of synthesis parameters, such as the molar ratio of water to TEOS, the molar ratio of water to surfactant, and the amount of base catalyst, are discussed.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1998.09a
• /
• pp.117-121
• /
• 1998

The Rapid Expansion of supercritical fluid Solutions (RESS) process was applied to particles coating. Experiments were conducted in a fluidized bed with an internal nozzle in the center of the reaction tube. Microcapsules (mean particle size : 49$\mu\textrm{m}$) prepared by spray drying method were used as the core particles. Supercritical CO2 solutions of paraffin were expanded through the nozzle in to the bed that was fluidized by air. Surface morphology prepared particles was observed by SEM. For the inspection of particle size change, particle size distributions were measured before and after coating. The releasing behavior of Mg2+ ions inspected by AA.

• Journal of the Korean Applied Science and Technology
• /
• v.21 no.1
• /
• pp.17-23
• /
• 2004

Silver bromide particles from 50 to 200${\AA}$ in diameter are prepared by mixing two microemulsions contaning the precursor salts $AgNO_3$ and KBr. The microemulsions are composed of AOT(bis(2-ethylhexyl) sodium sulfosuccinate), n-heptane and water. The particle diameters are measured on photomicrographs obtained by transmission electron microscopy. The size of the particles is generally larger than that of the water cores. The influence of both the concentration of precursor salts in the water cores of the microemulsoin and the size of these water cores on the size of the particles has been studied.