• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.357-362
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• 2013

Monodispersed polystyrene latex spheres (PLS) and PS-MPS/silica composite nanospheres were used to test high efficiency particulate air (HEPA) filters. Prior to filter tests, all nanospheres used in this work were characterized by measuring their average particle diameters and coefficients of variation (CV) for assessing them as artificial dusts. The average particle sizes of PLS and composite nanospheres could be well controlled in the range of 100~300 nm well by changing reaction temperature and the amount of a stabilizer during emulsion polymerization. The CV of all nanospheres were also in the range of 3~7%, lower than 15% that is the criterion for monodispersed particle distributions. Furthermore the results of HEPA filter tests show that all nanospheres used were quite proper as artificial dusts for testing air filters.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.119-126
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• 1991

This investigation was undertaken to study the synthesis of Boehmite by the hydrothermal homogeneous precipitation reaction of alum with urea. The reactions were carried out at a temperature of 100 to $250^{\circ}C$, 1 : 2 to 1 : 5 in a mole ratio of alum to urea and a reaction time of 0.5 to 20 hrs. The reaction precipitates were examined by X-ray diffraction analysis, scanning electron microscope, and chemical analysis. Under the condition of mole ratio 1 : 4 of alum to urea, the spherical and monodispersed amorphous aluminum sulfate hydrate was formed at $100^{\circ}C$, the mixture of spherical amorphous aluminum sulfate hydrate and Boehmite was formed at $150^{\circ}C$, Boehmite was formed at above $200^{\circ}C$, respectively. The reaction precipitates were dense, superior precipitable and filterable particle of average $2-4{\mu}m$.

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.1-11
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• 2017

We have dated the K-Ar, Ar-Ar and U-Pb ages of the Masan hornblende-biotite granite in the southern Cretaceous Gyeongsang basin to constrain its emplacement age. The ~108 Ma hornblende K-Ar age obtained in the study is similar to the previously reported Rb-Sr age. However, the single grain total fusion $^{40}Ar/^{39}Ar$ dating on hornblende failed to yield statistically meaningful ages because the isotopic system was open during its alteration. Thus the hornblende K-Ar age in the study is also unlikely to be reliable. The single grain total fusion $^{40}Ar/^{39}Ar$ dating on biotite yielded an average age of $75.8{\pm}3.0Ma$. Apart from scattered data in the range of ~45-75 Ma, the average age increased to ~80 Ma. The SHRIMP and LA-MC-ICPMS U-Pb isotopic compositions of zircon from the Masan hornblende-biotite granite yielded its emplacement age as $87.6{\pm}2.7Ma$ and $86.8{\pm}0.4Ma$, respectively. It is thus likely that the ~80 Ma $^{40}Ar/^{39}Ar$ age of biotite might reflect the cooling age of Masan hornblende-biotite granite or the thermal influences from later intense igneous activities in the Gyeongsang basin.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.295-305
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• 2004

Colloid and surface chemistry have been focused on surface area and surface energy. Local surface properties such as surface density, interaction, molecular orientation and reactivity have been one of interesting subjects. Systems of such surface energy being important would be listed as association colloid, emulsion, particle dispersion, foam, and 2-D surface and film. Such nanoparticle systems would be applied to drug delivery systems and functional cosmetics with biocompatible and degradable materials, while nanoparticles having its size of several nm to micron, and wide surface area, have been accepted as a possible drug carrier because their preparation, characteristics and drug loading have been inves-tigated. The biocompatible carriers were also used for the solubilization of insoluble drugs, the enhancement of skin absorption, the block out of UV radiation, the chemical stabilization and controlled release. Nano/micro emulstion system is classified into nano/microsphere, nano/microcapsule, nano/microemulsion, polymeric micelle, liposome according to its prep-aration method and size. Specially, the preparation method and industrial applications have been introduced for polymeric micelles self-assembled in aqueous solution, nano/microapsules controlling the concentration and activity of high concen-tration and activity materials, and monolayer or multilayer liposomes carrying bioactive ingredients.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.479-486
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• 2003

In this study, poly(DL-lactide-co-glycolide) nanoparticles loaded with water-insoluble vitamins such as vitamin A (Retinol) and vitamin E acetate were prepared by the emulsification diffusion method. Polymer solution was prepared by the two water-miscible organic solvent, such as ethanol and acetone. Because of its biocompatible property, polyethyleneglycol-polypropyleneglycol diblock copolymer was used as surfactant and stabilizer. The influence of some preparative variables on the nanoparticle formation and on the loading efficiency of active agents, such as the type and concentration of stabilizing agent, the stirring methods, the water/oil phase ratio and the polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles loaded with active agent, particle size and distribution were evaluated by the light scattering particle analyzer. The loading efficiency of active agents was evaluated by the UV-visible spectroscopy. As the results, particle size were 50-200 nm and dispersibility was monodisperse. The optimum loading efficiency of active agents was observed 50-60%. It was found that the appropriate of selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide good yield and favorable physical properties of PLGA nanoparticles.

• Journal of Adhesion and Interface
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• v.13 no.3
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• pp.101-108
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• 2012

Narrowly dispersed poly(BMA-co-MMA) and PBMA latices (PSD : 1.002~1.008) were synthesized successfully by surfactant-free emulsion polymerization with 2,2' azobis(2-methyl-propionamidine) dihydrochloride (AIBA) and $K_2S_2O_8$ (KPS). The number average particle diameter and the number average molecule weight were found to be 160~494 nm and (1.25~7.55) ${\times}10^4$, respectively. The influences of BMA/MMA ratio, monomer and initiator concentrations, addition of DVB/EGDMA crosslink agent, and polymerization temperature on the polymerization rates and on the particle size and molecular weight were studied. The rate of polymerization increased with increasing MMA concentration in BMA/MMA weight ratio. The particle diameter as well as the polymer molecular weight could be controlled easily by controlling the BMA/MMA weight ratio, monomer concentration, AIBA and KPS concentration, and polymerization temperature.

• Resources Recycling
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• v.16 no.5
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• pp.36-40
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• 2007

Platinum plays an important role in many applications because of its extraordinary physical and chemical properties. All these applications require the use of platinum in the finely divided state. Therefore the preparation of platinum nanoparticles by reducing platinum-surfactant salt with reducing agent in the solution was investigated in this study. The net interaction between C14TABr and $H_2[PtCl_6]$ in aqueous solution results in the formation of $[C14TA]_2[PtCl_6]$. The concentration of C14TABr and the concentration of $H_2[PtCl_6]$ has to be above cmc and 0.32 mM, respectively in order to obtain complex-micelle aggregation for mono dispersed Pt particles. Pt particle size increases with increasing $H_2[PtCl_6]$ and C14TABr concentration. And the shape of Pt particles was well controlled with increasing surfactant concentration.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.596-610
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• 2021

For application in adsorption process, we synthesized silica nanospheres by Stober method, and silica particles with wrinkled surface as well as macroporous silica particles were also fabricated by utilizing emulsion droplet as micro-reactors, followed by modification of the particle surface using suitable coupling agents containing amine groups. These particles exhibited improved adsorption capacity for heavy metal ions and anionic dyes, which were difficult to be removed by conventional silica particles without surface modification. Anionic dye, methyl orange could be removed almost completely by adsorption using porous silica particles modified using APTES. The adsorption efficiency of heavy metal like copper ions was close to 100%, when porous silica was used as adsorbent particles modified with AAPTS.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.740-745
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• 2018

The synthesis and characterization of amorphous calcium phosphate (ACP) nanoparticles were reported in this work. We show that relatively monodisperse ACP nanoparticles with a size of sub-100 nm can be prepared by a hydrothermal reaction of calcium chloride ($CaCl_2$) and disodium adenosine triphosphate ($Na_2ATP$) in the presence of sodium phytate as an additive. Their compositions and structures were confirmed using a series of material characterization techniques. Our results exhibit that ACP nanoparticles synthesized using sodium phytate enhanced the stability of maintaining their amorphous nature and prevented from a conversion to crystalline hydroxyapatite (HAP). ACP nanoparticles with the improved stability have potential uses in biomaterial applications in regenerative medicine.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.722-728
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• 2012

Urban sewer systems has a limitation of capacity of rainwater storage and problem of occurrence of untreated sewage, so adopting a storage facility for sewer flooding prevention and urban non-point pollution reduction has a big attention. The Korea Ministry of Environment has recently introduced a new concept of "multi-functional storage facility", which is crucial not only in preventive stormwater management but also in dealing with combined sewer overflow and sanitary sewer discharge, and also has been promoting its adoption. However, reserving a space for a single large-scale storage facility might be difficult especially in urban areas. Thus, decentralized construction of small- and midium-sized storage facilities and its operation have been introduced as an alternative way. In this paper, we propose a model predictive control scheme for an optimized operation of distributed storage facilities and sewer networks. To this aim, we first describe the mathematical model of each component of networks system which enables us to analyze its detailed dynamic behavior. Second, overflow locations and volumes will be predicted based on the developed network model with data on the external inflow occurred at specific locations of the network. MPC scheme based on the introduced particle swarm optimization technique then produces the optimized the gate setting for sewer network flow control, which minimizes sewer flooding and maximizes the potential storage capacity. Finally, the operational efficacy of the proposed control scheme is demonstrated by simulation study with virtual rainstorm event.