• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.53-59
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• 2009

The purpose of this research is particle shape evaluation of granular soil and aggregate using Digital Image Process(DIP). DIP is very useful to measure the roughness and particle shape of aggregates. Couple of aggregates, like standard sand, two different crushed stones, and two different marine aggregates, have been employed. Shape factor of two different marine aggregates is ranged 0.35 to 0.54. Crushed stone I is that of 0.74 which is highly flat, but standard sand is elongated shape. Especially, two marine aggregate showed a big difference of width and length which meaned a long shape. There is any significant difference of elongation ratio and flakiness for each aggregate with different measuring system, like direct measurement of vernier calipers and DIP method. Within the limited test results, DIP is one of useful to get the particle shape of aggregate with limitation of measuring errors and to apply the particle distribution curve.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1139-1150
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• 1999

The evolution of silica aggregate particles in coflow diffusion flames has been studied experimentally using light scattering and thermophoretic sampling techniques. The measurements of scattering cross section from $90^{\circ}$ light scattering have been utilized to calculate the aggregate number density and volume fraction using with combination of measuring the particle size and morphology through the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh-Debye-Gans and Mie theory for fractal aggregates and spherical particles, respectively. Of particular interests are the effects of flame temperature on the evolution of silica aggregate particles. As the flow rate of $H_2$ increases, the primary particle diameters of silica aggregates have been first decreased, but, further increase of $H_2$ flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal aggregates finally become spherical particles. The variation of primary particle size along the upward jet centerline and the effect of burner configuration have also been studied.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.501-509
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• 2004

Unipolar diffusion charging of non-spherical particles was investigated for various particle shapes. We researched with TiO$_2$agglomerates produced by the thermal decomposition of titanium tetraisopropoxide (TTIP) vapor. TTIP was converted into TiO$_2$, in the furnace reactor and was subsequently introduced into the sintering furnace. Increasing the temperature in the sintering furnace, aggregates were restructured into higher fractal dimensions. The aggregates were classified according to their mobility using a differential mobility analyzer. The projection area and the mass fractal dimension of particles were measured with an image processing technique performed by using transmission electron microscope (TEM) photograph. The selected aggregates were charged by the indirect photoelectric-charger and the average number of charges per particle was measured by an aerosol electrometer and a condensation particle counter. For the particles of same mobility diameter, our results showed that the particle charge quantity decreases as the sintering temperature increases. This result is understandable because particles with lower fractal dimension have larger capacitance and geometric surface area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.4
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• pp.200-206
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• 2012

The artificial aggregate composing of coal bottom ash and waste catalyst slag (7 : 3, wt%) were fabricated using direct sintering method and, the bloating properties of aggregates were investigated as a function of raw material particle size and sintering temperature. Most of the artificial aggregates sintered at over $1150^{\circ}C$ showed the bloating phenomenon regardless of particle size of the raw materials. Consequently, the specific gravity of the aggregates was drastically decreased to below 1.4. The aggregates containing waste catalyst slag of $90{\mu}m$ under among the W-series specimens, however, did not show the noticeable bloating phenomenon. For the aggregates sintered at lower temperature as $1050{\sim}1150^{\circ}C$, the specific gravity increased with particle size of raw materials. Also, the water absorption of all aggregates decreased with the sintering temperature. The aggregates fabricated in this study met the lightweight aggregate standard showing the specific gravity 1.7~1.4 and water absorption 8~19 % and, therefore, can be applicable for the various fields.

• Industry Promotion Research
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• v.6 no.4
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• pp.1-9
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• 2021

The purpose of this study is to manufacture lightweight aggregates for recycling water treatment sludge, to identify the physical properties of the aggregates, and present a method of utilizing the manufactured lightweight aggregates. The chemical composition and thermal properties were examined via a raw materials analysis. The aggregate examined here was fired by the rapid sintering method and the single-particle density and water absorption rate were measured. Water treatment sludge has high ignition loss and high fire resistance. When 30wt% of purified sludge was added, the single-particle density of the aggregates was in the range of 0.8~1.2g/cm³ at a temperature of 1,150~1,200℃. At temperatures of 1200℃ or higher, ultra-light aggregates having a single-particle density of 0.8 or less could be produced. When applied to concrete by replacing the general aggregate in the concrete, a specimen having strength values of 200 to 450 kgf/cm² on 28 days was obtained, and when applied as a filter material, the performance was equal to or higher than that of ordinary sand.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.212-217
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• 2015

Ships and marine structures have a lot of problems in their high maintenance and operating cost by biofouling. A biofouling occurrs by the adhesion of marine microorganism, algae and bacteria. In this study, the aim is to prevent or to reduce the biofouling phenomena through silver nano-particle coating on artificial light-weight aggregates and geopolymer. The antibacterial activity on them is tested according to ASTM E2149-2013a. The test results showed, it is estimated that silver nano-particles removed 99.99 % of bacteria. Specimens were set up in the sea side of field test area in Korea Institute of Ocean Science and Technology (KIOST) and have been observed for five months. The anti-biofouling effect and difference in weight change rate have been detected two months later after the installation. Because silver nanoparticles inhibit bacterial growth and kill the cells by destroying bacterial membranes, silver nano-particle coating on artificial lightweight aggregates is a well-suited and eco-friendly method for preventing biofouling in the sea up to 5 months.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.227-237
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• 2002

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that the electric charges accumulated on an aggregate were located on its center of mass, and aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. In the simulation, the fractal dimension for the uncharged aggregate was D$\_$f/ = 1.761. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states. In the bipolar charge state, the average sizes of aggregates were larger than that of the uncharged state in the early and middle stages of aggregation process, but were almost the same as the case of the uncharged state in the final stage. On the other hand, in the unipolar charge state, the average size of aggregates and the dispersion of particle volume decreased with the increasing of the charge quantities.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.147-148
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• 2022

Due to recent climate abnormalities, the form of rainfall is changing to localized torrential rains. Localized torrential rains cause flooding in urban areas. In addition, in various industrial fields, there are cases where materials necessary for the process are kept outdoors, and damage from material loss and flooding of stockyards occurs during heavy rain. Accordingly, it is necessary to introduce a drainage layer where flooding is expected. This drainage layer places the aggregate inside and allows rainwater to penetrate and drain into the voids between the aggregates. However, the amount of voids differs according to the particle size distribution and particle size of the aggregate, and the drainage performance varies according to the compositional location of the aggregate. Therefore, in this study, the drainage characteristics according to the particle size, particle size, and compositional location of aggregates are analyzed using a fluid analysis program.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.541-545
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• 2000

For the sustained release formulation of recombinant human growth hormone (rhGH), dissociable rhGH aggregates were microencapsulated within poly(D,L-lactic-co-glycolic acid) [PLGA] microparticles. rhGH aggregates with 2 - 3 m Particle diameter were first produced by adding a small volume of aqueous rhGH solution into a partially water miscible organic solvent phase(ethyl acetate) containing PLGA. These rhGH aggregates were then microencapsulated within PLGA polymer phase by extracting ethyl acetate into an aqueous phase pre-saturated with ethyl acetate. The resultant microparticles were 2 - 3 m in diameter similar to the size of rhGH aggregates, suggesting that PLGA polymer was coated around the protein aggregates. Release profiles of rhGH from these microparticles were greatly affected by changing the volume of the incubation medium. The release rhGH species consisted of mostly monomeric form with having a correct conformation. This study reveals that sustained rhGH release could be achieved by microencapsulating reversibly dissociable protein aggregates within biodegradable polymers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.109-110
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• 2022

Recently, it tend to increase the high-rise and large-scale of buildings and the developtment of construction technology can to be applied reinforced concrete structures to high-rise buildings. However, when a high-rise buildings is constructed with reinforced concrete, it has a disadvantage that buildings weight increases. In order to resolve the weight of reinforced concrete structures, various types of lightweight aggregates become development and research. Although lightweight aggregates can be reduced the weight of concrete, the strength of ITZ(Interfacial Transition Zone) is lowered due to its less strength than natural aggregates. In this study, an experimental study was conducted to coat the surface of lightweight aggregates with GGBFS(ground granulated blast furnace slag) to improve the strength of cement matrix mixed with lightweight aggregates. Result of this experimental study shows that the compressive strnegth of the surface coating lightweight aggregates was higher than general lightweight aggregates. Also, it was considered that this is because the pore at the ITZ of the surface-coated lightweight aggregates mixed cement matrix are filled with GGBFS fine particle.