• Korean Journal of Materials Research
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• v.26 no.10
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• pp.570-576
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• 2016

Using the ultrasonic pyrolysis method, spherical $SiO_2$ powders were synthesized from aqueous $SiO_2$ sol as a starting material. The effects of pyrolysis conditions such as reaction temperature, $SiO_2$ sol concentration, and physical properties of precursor were investigated for the morphologies of the resulting $SiO_2$ powders. The particle size, shape, and crystallite size of the synthesized $SiO_2$ powders were demonstrated according to the pyrolysis conditions. Generally, the synthesized $SiO_2$ particles were amorphous phase and showed spherical morphology with a smooth surface. It was revealed that increased crystallite size and decreased spherical $SiO_2$ particle size were obtained with increases of the pyrolysis reaction temperature. Also, quantity of spherical $SiO_2$ particles decreased with the decrease in the concentration and surface tension of the precursor.

• Particle and aerosol research
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• v.14 no.3
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• pp.65-72
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• 2018

Core-shell structured $Fe_3O_4/graphene$ composites were synthesized by aerosol spray drying process from a colloidal mixture of graphene oxides and $Fe_3O_4$ nanoparticles. The structural and electrochemical performance of $Fe_3O_4/graphene$ were characterized by the field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, cyclic voltammetry, and galvanometric discharge-charge method. Core-shell structured $Fe_3O_4/GR$ composites were synthesized in different mass ratios of $Fe_3O_4$ and graphene oxide. The composite particles were around $3{\mu}m$ in size. $Fe_3O_4$ nanoparticles were encapsulated with a graphene. Morphology of the $Fe_3O_4/graphene$ composite particles changed from a spherical ball having a relatively smooth surface to a porous crumpled paper ball as the content of GO increased in the composites. The $Fe_3O_4/GR$ composite fabricated at the weight ratio of 1:4 ($Fe_3O_4:GO$) exhibited higher specific capacitance($203F\;g^{-1}$) and electrical conductivity than as-fabricated $Fe_3O_4/GR$ composite.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.59-64
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• 2008

The mechanical properties of liquid phase sintered (LPS) SiC materials, with the addition of oxide powder, were investigated, in conjunction with a detailed analysis of their microstructures. LPS-SiC materials were fabricated at a temperature of 1820 $^{\circ}C$ under an argon atmosphere, using three different starting sizes of SiC particles. The sintering additive for the fabrication of the LPS-SiC materials was an $Al_2O_3-Y_2O_3$ mixture with a constant composition ratio ($Al_2O_3/Y_2O_3$: 1.5). The particle sizes of the commercial SiC powderswere 30 nm, 0.3 $\mu$m, and 3.0 $\mu$m. The flexural strength of the LPS-SiC materials was also examined at elevated temperatures. A decrease in the starting size of the SiC particles led to an increase in the flexural strength of the LPS-SiC materials, accompanying a highly dense morphology with the creation of a secondary phase. Such a secondary phase was identified as $Y_3Al_2(AlO_4)2$. The flexural strength of the LPS-SiC materials greatly decreased with an increase in the test temperature, due to the creation of a large amount of pores.

• Fashion & Textile Research Journal
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• v.10 no.5
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• pp.748-755
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• 2008

The purpose of this study is to investigate the effect of chitosan treatment on the dyeing of cotton fabric using charcoal as colorants. Particle size of charcoal, dyeability(K/S), SEM morphology of dyed fabrics and color fastness were also investigated. In this study, cotton fabrics were treated with a crosslinking agent epichlorohydrin in the presence of chitosan to provide the cotton fabrics the dyeing properties of natural dye by the chemical linking of chitosan to the cellulose structure. The results obtained were as follows; Mean average diameter of charcoal was 1.44 ${\mu}m$. According to various conditions, the dyeing effects of 1% chitosan treatment on the dyeing of cotton fabrics using charcoal were the highest with 10%(owb) of charcoal at $90^{\circ}C$ for 120minutes and non-treatment of cotton fabrics were the highest with 15%(owb) of charcoal at $90^{\circ}C$ for 150minutes. Overall, K/S value of 1% chitosan treatment of cotton fabrics on the natural dyeing using charcoal was higher than non-treatment of cotton fabrics. It was observed the surfaces of cotton fabrics treated with chitosan were adsorbed with charcoal powders of particle size more than a non-treated chitosan fabric by SEM. The cotton fabrics were dyed with blackish gray color by charcoal gradually according to treating chitosan. The K/S value, that is indicative of dye affinity, became higher as the increase of treated chitosan concentration. The color fastness of charcoal, washing and light fastness was excellent as 4-5 grade.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.61-66
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• 2006

Over the past 20 years there has been a revolution involving the use of nano or macro size particles as drainage and retention systems during the manufacture of paper. More recently a group of patented technologies called Synthetic Mineral Microparticles (SMM) has been invented and developed. This system has potential to further promote the drainage of water and retention of fine particles during papermaking. Prior research, as well as our on preliminary research showed that the SMM system has advantages in both of drainage and retention compared with montmorillonite (bentonite), which one of the most popular materials presently used in this kind of application. In spite of the demonstrated advantages of this SMM system, the properties and activity of SMM particles in the aqueous state have not been elucidated yet. Streaming current titrations with highly charged polyelectrolytes were used to measure the charge properties of SMM and to understand the interactions among SMM particles, fibers, fiber fines, and cationic polyacrylamide (cPAM) as a retention aid. It was found that pH profoundly affects the charge properties of SMM, due to the influence of Al-ions and the Si-containing particle surface. SEM pictures, characterizing the morphology, geometry and size distribution of SMM, showed an broad distribution of primary particle size. Dilution of SMM mixturee appeared to wash out particles smaller than 100 nm from the surface of larger particles, which themselves appeared to be composed of fused primary particles. DSC thermoporometry was used to measure the size distribution of nanopores within SMM particles.

• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.34-40
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• 1998

Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. Therefore, we studied that another viscosity chitosan were prepared from chitin which were deacetylated under various concentration of NaOH solution, reaction time and temperature by the application of Mirna's method. The major parameters for these manufacturing methods were found to be concentration of alkali solution, reaction time and temperature etc. Besides, we studied that various chitosan derivatives were prepared from chitin by crosslinkage with epichlorohydrin and 1,3-dichloropropanol. The effects of these parameters on another viscosity(molecular weight) chitosan and crosslinked chitosan dervatives were investigated by various analysis apparatus. SEM analysis showed that both chitin and chitosan had a particle shaped morphology and another molecular weight chitosan according to the particle size was much smaller than that of chitin.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.537-542
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• 2011

Magnesium hydroxide as a non-halogen flame retardant has increasing attention due to its non-toxicity, high decomposition temperature and smoke suppressant ability during combustion. For the application of magnesium hydroxide retardant to the textile by soaking and coating method, the prerequisite for the coating is a small particle size, stable dispersion, and adhesion to the textile. The dispersion of $Mg(OH)_2$ particles and stability of the coating was checked by monitoring the change of transmittance and backscattering by varying the types of dispersion agents, binder, solvent, and $Mg(OH)_2$ source, and their compositions in the coating. The $Mg(OH)_2$ dispersion coating was applied to PET(poly(ethylene terephthalate)) non-woven textile. The physical properties are characterized by surface morphology, amount of coating, particle dispersion, and adhesion test. The flame retardant $Mg(OH)_2$ coated textile has been compared by limited oxygen index(LOI) and thermal gravimetry and differential scanning calorimetry(TG-DSC). It was found that phosphorous additive may give synergistic effect on $Mg(OH)_2$ flame retardant coating to make the flame retardant PET non-woven textile.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.865-871
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• 2016

In recent years, traditional scaffold fabrication techniques such as gas foaming, salt leaching, sponge replica, and freeze casting in tissue engineering have significantly limited sufficient mechanical property and cell interaction effect due to only random pores. Fused deposition modeling is the most apposite technology for fabricating the 3D scaffolds using the polymeric materials in tissue engineering application. In this study, 3D slurry mould was fabricated with a blended biphasic calcium phosphate (BCP)/Silica/Alginic acid sodium salt slurry in PCL mould and heated for two hours at $100^{\circ}C$ to harden the blended slurry. 3D dual-pore BCP/Silica scaffold, composed of macro pores interconnected with micro pores, was successfully fabricated by sintering at furnace of $1100^{\circ}C$. Surface morphology and 3D shape of dual-pore BCP/Silica scaffold from scanning electron microscopy were observed. Also, the mechanical properties of 3D BCP/Silica scaffold, according to blending ratio of alginic acid sodium salt, were evaluated through compression test.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2277-2284
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• 2016

Ribosome-inactivating protein (RIP) from Mirabilis jalapa L. leaves has cytotoxic effects on breast cancer cell lines but is less toxic towards normal cells. However, it can easily be degraded after administration so it needs to be formulated into nanoparticles to increase its resistance to enzymatic degradation. The objectives of this study were to develop a protein extract of M. jalapa L. leaves (RIP-MJ) incorporated into nanoparticles conjugated with Anti-EpCAM antibodies, and to determine its cytotoxicity and selectivity in the T47D breast cancer cell line. RIP-MJ was extracted from red-flowered M. jalapa L. leaves. Nanoparticles were formulated based on polyelectrolyte complexation using low viscosity chitosan and alginate, then chemically conjugated with anti-EpCAM antibody using EDAC based on carbodiimide reaction. RIP-MJ nanoparticles were characterised for the particle size, polydispersity index, zeta potential, particle morphology, and entrapment efficiency. The cytotoxicity of RIP-MJ nanoparticles against T47D and Vero cells was then determined with MTT assay. The optimal formula of RIP-MJ nanoparticles was obtained at the concentration of RIP-MJ, low viscosity chitosan and alginate respectively 0.05%, 1%, and 0.4% (m/v). RIP-MJ nanoparticles are hexagonal with high entrapment efficiency of 98.6%, average size of 130.7 nm, polydispersity index of 0.380 and zeta potential +26.33 mV. The $IC_{50}$ values of both anti-EpCAM-conjugated and non-conjugated RIP-MJ nanoparticles for T47D cells (13.3 and $14.9{\mu}g/mL$) were lower than for Vero cells (27.8 and $33.6{\mu}g/mL$). The $IC_{50}$ values of conjugated and non-conjugated RIP-MJ for both cells were much lower than $IC_{50}$ values of non-formulated RIP-MJ (>$500{\mu}g/mL$).

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.889-894
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• 1999

Preparation of micron size polymer particles which have desired morphology, size, and structure by emulsion polymerization is very difficult due to coagulation of latex particles and formation of second generation particles. But there are attractive merits such as preparation of structural and functional polymer particles in seeded emulsion polymerization. Seeded emulsion polymerization of n-butyl acrylate(BA) was carried out to investigate the effects of stirring rate, reaction temperature, concentration of initiator, emulsifier, and cross-linking agent on the particle size and size distribution. By the combination of suitable reaction conditions, we succeeded in preparing $0.14{\sim}3.67{\mu}m$ diameter of poly(n-butyl acrylate)(PBA) particles using sequential seeded emulsion polymerization.