• Journal of Korean Society for Atmospheric Environment
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• v.29 no.5
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• pp.634-641
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• 2013

Condensing species behaviour downstream of a combustor was discussed with particle size distribution in this study. The effects of operating conditions in a biomass combustion facility, i.e. concentration of condensing species, temperature gradient, residence time and injection of adsorbents, on particle size distribution were investigated. Pyroligneous liquid which was completely vaporized at the temperature higher than $350^{\circ}C$ was used as a representative of condensing gaseous species. We found that particle size downstream of a combustor increased with increasing heating temperature (i.e. concentration of condensing species) and residence time. However, temperature gradient was not an important factor to control the particle size. The addition of $SiO_2$ precursor as an adsorbent could effectively prevent the particle formation by adsorbing condensing gaseous species on $SiO_2$ particles, and increased the particle size up to 300 nm, resulting in increasing particle removal efficiency in a conventional air pollution control device.

• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.323-329
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• 1997

Particle growth of BT-oxalate was investigated in aging with various additives such as glycerine, chloro-form and NaCl. Their effects on size and morphlogy of particle was examined. It can be known that particle size distributions of BT-oxalate precipitate varied with amounts of these additivies. With small amounts of these additives, particle growth of nonuniform distribution was occurred, but above 1 mole percent of those additives, uniform size distributions of about 0.4 ${\mu}{\textrm}{m}$ could be obtain. There was little difference among the effects by the kinds of additives. From the decomposition of uniform BT-oxalate, BaTiO3 powders of about 0.3${\mu}{\textrm}{m}$ could be obtained.

• Geomechanics and Engineering
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• v.5 no.6
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• pp.499-517
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• 2013

In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.

• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.454-460
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• 2012

The nano-sized zirconia powders were synthesized in an impregnation method using pulp and $ZrOCl_2{\cdot}8H_2O$ as an initial material. The synthesized powders were characterized by XRD and FE-SEM. The particle size of the powder was controlled by preparation conditions, such as drying temperature and time. As a result of the various drying and calcination conditions, 30~50 nm sized homogeneous zirconia particles were obtained at $800^{\circ}C$ for 1 h. Crystallization and the rapid growth of particles were accelerated with increasing calcination temperature and time. Tetragonal phase generated below $800^{\circ}C$ were transferred to monoclinic phase with increasing calcination temperature and time. Moreover, above $800^{\circ}C$, heat treatment time had very large influence on the particle growth, and the change of drying condition also had large influence on the growth of a crystal.

• Computers and Concrete
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• v.15 no.6
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• pp.989-999
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• 2015

An advanced continuum-based multi-physical single particle model was recently introduce for the hydration of tricalcium silicate ($C_3S$). In this model, the dissolution and the precipitation events are modeled as two different yet simultaneous chemical reactions. Product precipitation involves a nucleation and growth mechanism wherein nucleation is assumed to happen only at the surface of the unreacted core and product growth is characterized via a two-step densification mechanism having rapid growth of a low density initial product followed by slow densification. Although this modeling strategy has been shown to nicely mimic all stages of $C_3S$ hydration - dissolution, dormancy (induction), the onset of rapid hydration, the transition to slow hydration and prolonged reaction - the major criticism is that many adjustable parameters are required. If formulated correctly, however, the model parameters are shown here to be statistically independent and significant.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.957-960
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• 2008

The influences of silicon and MgO seed particle on the reconstruction characteristics of MgO protective layer were investigated to clarify the mechanism of reconstruction and exaggerated grain growth (EGG) in AC-PDP. The reconstruction and EGG are closely correlated with the driving force for nucleation and growth, interface energy and initial size distribution of MgO protective layer in plasma space during discharge in AC-PDP.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.168-173
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• 2000

Flame aerosol synthesis technology refers to the formation of fine particles from gases in flame and is widely used in practical materials processing. In this paper, an experimental investigation was performed on growth of the silica particles that were generated in $H_2/O_2$ Diffusion Flame by the direct injection or TEOS using Electro-spraying method. in this flame aerosol synthesis, four main parameters or nos interaction (flame temperature, residence time or particle in flame, TEOS flow rate, applied voltage) for particle generation and growth was investigated along the axial direction above the burner. A fairly monodisperse non-aggregated particles were successfully obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.333-336
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• 2021

Oxide YBCO bulk superconductors are manufactured using the melt process. Because seed crystal growth method utilizes a slow-spreading layer-by-layer reaction, a long-term heat treatment is required to manufacture a single-crystal specimen of several cm. In this study, the melt process method was applied to compensate for the shortcomings of the seed crystal growth method. The thickness of the upper and lower pellets of the YBCO bulk was molded to 40 mm, and YBCO superconductor was produced by heat treatment. The measurement results of capture magnetism was in line with the literature. This results in a relationship that the higher the growth of Y211 particle in the YBCO, the higher the superconducting properties. We analyzed the YBCO superconductor, focusing on the Y₂BaCuO₅ particle distribution.

• Journal of Bio-Environment Control
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• v.12 no.2
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• pp.77-82
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• 2003

The effect of the particle size of perlite and irrigation amount on the growth, root activity and mineral competition of tomato was investigated in a recycling system. The particle sizes used were small (SPP, øl∼2 mm), medium (MPP, ø2∼3 mm), (LPP. ø4∼5 mm). Plant height, fresh weight and dry weight of tomato at the earlier growth stage were good at 3.0 L/day in MPP and LPP, but these were not significantly affected by irrigation amount in MPP, Fruit number, weight and yield increased at 1.5 L/day in SPP and 3.0 L/day at MPP or LPP, Deformed fruits tended to increase at higher irrigation amounts regardless of particle size. Root activity increased with increasing particle size with higher irrigation amount during early stage after transplanting, but remarkably decreased at 3.0 L/day in SPP as compared with the others at 100 days. Mineral contents of plants after harvest were higher at MPP and LPP than SPP, but were highest at 3.0 L/day in LPP. In conclusion, it was regarded that tomato growth in a recycling system was optimal at MPP or LPP with irrigation amount of B.0 L/day.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.222-229
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• 1993

Total suspended particles in the atmosphere were collected on the quartz fiber filters using an ANdersen Hi-volume air sampler from March 1989 to October 1989 and from June 1990 to February 1991, at Chung-Ang University in Seoul. A total amount of eight heavy metals (Cr, Zn, Cd, Pb, Fe, V, Ti, Mn) in total suspended particles were determined by ICP spectrophotometer. The annual arithmetic mean concentration of total suspended particle was 162.3$\mug/m^3$ and eight metals(Cr, Zn, Cd, Pb, Fe, V, Ti, Mn) were 11.6, 609.2, 3.5, 337.1, 2739.5, 15.1, 89.4 and 100.5ng/$m^3$, respectively. The concentration of total suspended particle was highest in the spring(343.7$\mug/m^3$) and lowest in the summer(91.8$\mug/m^3$). These heavy metals were distinguished into two groups in terms of their particle size distribution. The contents of first-group heavy metals (Fe, Ti, Mn) were increased in accordance with the growth of the particle size. The contents of the second-group ones such as Pb, Cd, V, and Zn, on the contrary, came to increase according as the particle size reduced. Statistical analysis indicated that there was a correlation between total suspended particle and Fe in coarse particles, and between total Suspended Particle and Zn, Pb in fine particle.