• Textile Coloration and Finishing
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• v.19 no.6
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• pp.28-34
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• 2007

The optical and physical properties of alkyl-substituted anthraquinoid dyes were investigated in terms of dyeing of pure polypropylene fiber. The length of alkyl substituents of the dyes did not affect the molar extinction coefficient and maximum absorption wavelength of them. The use of a double-tailed cationic surfactant, didodecyldimethylammonium bromide(DDDMAB), could make the hydrophobic dyes dispersed in water effectively. As the amount of DDDMAB increased, the average particle size of dye dispersion decreased. Maximum color strength of the fabrics was shown in the case that 1.5 molar ratio of DDDMAB was used. As for the fastness properties, commercially acceptable result was obtained in general.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.642-648
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• 2002

Barium Titanate(BaTiO$_3$) nanoparticles were prepared at 22$0^{\circ}C$ through glycothermal process by using barium hydroxide and amorphous titanium hydrous gel as precursor and 1,4-butanediol and distilled water as solvent. It is demonstrated that the size of BaTiO$_3$ particles can be controlled by reaction conditions such as various content of 1,4-butanediol/distilled water volume ratio. This processing method can fabricate BaTiO$_3$ powders, which have a narrow distribution and exhibit good dispersion. The particle size of BaTiO$_3$ powders obtained by glycothermal process were about 50 nm to 200 nm on the condition that reaction temperature was 22$0^{\circ}C$ and holding time was 24 h.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3362-3366
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• 2013

A simple and quick separation technique for selenite in natural water was developed using $TiO_2$@$SiO_2/Fe_3O_4$ nanoparticles. For the synthesis of nanoparticles, a polymer-assisted sol-gel method using hydroxypropyl cellulose (HPC) was developed to control particle dispersion in the synthetic procedure. In addition, titanium butoxide (TBT) precursor, instead of the typical titanium tetra isopropoxide, was used for the formation of the $TiO_2$ shell. The synthesized nanoparticles were used to separate selenite ($Se^{4+}$) in the presence of $Se^{6+}$ or selenium anions for the photocatalytic reduction to $Se^0$ atom on the $TiO_2$ shell, followed by magnetic separation using $Fe_3O_4$ nanoparticles. The reduction efficiency of the photocatalytic reaction was 81.4% at a UV power of 6W for 3 h with a dark adsorption of 17.5% to the nanoparticles, as determined by inductively coupled plasma-mass spectrometry (ICP-MS). The developed separation method can be used for the speciation and preconcentration of selenium cations in environmental and biological analysis.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.797-801
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• 2001

In this study, the solution combustion method was employed to synthesize stoichiometric mullite, and hence the attrition process was employed to prepare ultrafine mullite particles with nano size. The thermal decomposition behavior and partial pressure of equilibrium species of both oxidizer and fuel were considered during solution combustion process. The synthesized product was mullite phase with 40 nm crystalline size, and the alumina contents of the product by TEM/EDS quantity analysis was 3.12$\pm$04 mole. The result showed that the synthesized mullite was almost close to the it's stoichiometric composition. For attrition process, the dispersion behavior of the mullite suspension was controlled and was comminuted with the condition of 800 rpm for 4 hours using 0.3 mm zirconia ball media. As a result of comminution, the mean particle size was 80 nm.

• Korean Journal of Materials Research
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• v.28 no.9
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• pp.495-498
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• 2018

Intermetallic compound matrix composites have been expected to be established as high temperature structural components. $Ni_3Al$ is a representative intermetallic alloy, which has excellent ductility even at room temperature by adding certain alloying elements. $Ni_3Al$ matrix composites with aluminum oxide particles, which are formed by the in-situ reaction between the alloy and aluminum borate whiskers, are fabricated by a powder metallurgical method. The addition of aluminum borate whiskers disperses the synthetic aluminum oxide particles during sintering and dramatically increases the strength of the composite. The uniform dispersion of reaction synthesized aluminum oxide particles and the uniform solution of boron in the matrix seem to play an important role in the improvement in strength. There is a dramatic increase in strength with the addition of the whisker, and the maximum value is obtained at a 10 vol% addition of whisker. The $Ni_3Al$ composite with 10 vol% aluminum oxide particles $0.3{\mu}m$ in size and with 0.1 wt% boron powder fabricated by the conventional powder metallurgical process does not have such high strength because of inhomogeneous distribution of aluminum oxide particles and of boron. The tensile strength of the $Ni_3Al$ with a 10 vol% aluminum borate whisker reaches more than twice the value, 930 MPa, of the parent alloy. No third phase is observed between the aluminum oxide and the matrix.

• Journal of Dairy Science and Biotechnology
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• v.23 no.1
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• pp.19-26
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• 2005

Nanofood can be simply defined as natural polymer particles containing functional food materials in nanoscale that are synthesized by polymerization or emulsification process. They have very uniform diameters in the range of 1 to 100nm and extensive surface areas due to the small particle size in spite of their non-porosity. Although the technique to produce nanofood has not long developing history, many works have been achieved in various fields. Nanofood has a lot of special advantages, such as functionality, diversity, applicability, etc. In case of the domestic food industries, however, the accumulation of related technique is insufficient against developed countries except used food materials. Also, it is difficult to acquire technical know-how from the developed countries that possess those technologies. We have been studied on preparing functional nanofood and developing new production processes since 1999. Last 5 years we have laid the foundation on the preparation of nanofood and now are focusing on developing new processes of nanofood and expending the field of its applications.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.354-360
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• 2001

By applying Eshelby's theory on the'transformation' and' inhomogeneity'problems of an ellipsoidal inclusion, a microscopic stress-strain is formulated for a composite material consisting of a matrix and a large number of aligned ellipsoidal inclusions. Some of the composites of practical interest, such as unidirectionally fiber- reinforced, Particle dispersion strengthened and layered composites can be treated by changing the axial ratios of the ellipsoidal inclusion. The macroscopic stress-strain relation obtained is applicable to elastic and elasto-plastic deformation of the composite in uniform loading.

• Journal of Pharmaceutical Investigation
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• v.37 no.1
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• pp.51-55
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• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1733-1737
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• 2009

A new cathode material based on Li$Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCA)/polyaniline (Pani) composite was prepared by in situ self-stabilized dispersion polymerization in the presence of LNCA. The materials were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties including galvanostatic charge-discharge ability, cyclic voltammetry (CV), capacity, cycling performance, and AC impedance were measured. The synthesized LNCA/Pani had a similar particle size to LNCA and exhibited good electrochemical properties at a high C rate. Pani (the emeraldine salt form) interacts with metal-oxide particles to generate good connectivity. This material shows good reversibility for Li insertion in discharge cycles when used as the electrode of lithium ion batteries. Therefore, the Pani coating is beneficial for stabilizing the structure and reducing the resistance of the LNCA. In particular, the LNCA/Pani material has advantageous electrochemical properties.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.519-526
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• 2006

A full-factorial design of experiments with three input factors and two levels for each factor including center points was utilized for the preparation and characterization of twelve types of $BaTiO_3$ slips for tape casting. Ceramic powders with different particle sizes, different milling methods such as high energy milling and conventional ball milling, and two types of dispersant with different polymeric species were chosen as input factors in order to investigate their effects on slip and on green tape properties. Tape casting, a small rectangular-shaped K-square preparation, characterization and quantitative data analysis using statistical software were followed. Ceramic powder was the most significant among three input factors for the output responses of slip viscosity and green tape density, showing more favorable results with large particles than with very fine ones. In addition, high energy milling for only 30 min was more efficient than 24h of conventional ball milling in terms of powder dispersion and milling. The optimum condition based on the experimental results was a slip exposed to high energy milling with large ceramic particles along with a methylethyl acetate dispersant.