• Korean Journal of Materials Research
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• v.22 no.6
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• pp.316-320
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• 2012

$Co_3O_4$, $Al_2O_3$ and $Co_3O_4$/$Al_2O_3$ mesoporous powders were prepared by a sol-gel method with starting matierals of aluminum isopropoxide and cobalt (II) nitrate. A P123 template is employed as an active organic additive for improving the specific surface area of the mixed oxide by forming surfactant micelles. A transition metal cobalt oxide supported on alumina with and without P123 was tested to find the most active and selective conditions as a heterogeneous catalyst in the reaction of styrene epoxidation. A bBlock copolymer-P123 template was added to the staring materials to control physical and chemical properties. The properties of $Co_3O_4$/$Al_2O_3$ powder with and without P123 were characterized using an X-ray diffractometer (XRD), a Field-Emission Scanning Electron Microscope (FE-SEM), a Bruner-Emmertt-Teller (BET) surface analyzer, and $^{27}Al$ MAS NMR spectroscopy. Powders with and without P123 were compared in catalytic tests. The catalytic activity and selectivity were monitored by GC/MS, $^1H$, and $^{13}C$-NMR spectroscopy. The performance for the reaction of epoxidation of styrene was observed to be in the following order: [$Co_3O_4$/$Al_2O_3$ with P123-1173 K > $Co_3O_4$/$Al_2O_3$ with P123-973 K > $Co_3O_4$-973 K>$Co_3O_4$/$Al_2O_3$-973 K > $Co_3O_4$/$Al_2O_3$ with P123-1473 K > $Al_2O_3$-973 K]. The existence of ${\gamma}$-alumina and the nature of the surface morphology are related to catalytic activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.179-179
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• 2016

A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.3
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• pp.135-142
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• 2018

In this study, we have fabricated n-type $Bi_2Te_{2.85}Se_{0.15}$ compounds by different processing routes such as crushing, milling and mixing respectively. Subsequently, the obtained powders were consolidated by spark plasma sintering (SPS). The phase crystallinity of bulk samples were identified using X-ray diffraction technique. Powder morphology and fracture surface of bulk samples were observed using the scanning electron microscopy (SEM). The Seebeck coefficient and electrical conductivity values were significantly increased for the milling sample than crushing and mixing samples. As a result, the maximum power factor was obtained $2.4mW/mK^2$, which is thrice than that of crushing process. The maximum figure of merit (ZT) of 0.77 was achieved at 400 K for the milling sample. Furthermore, relatively high hardness and density values were noticed for the different processed samples.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.224-228
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• 2014

Recently, the demands for separation/recovery of valuable metals such as nickel or tin from copper based alloys has been attracting much attention from the viewpoints of environmental protection and resource utilization. In this report, experimental results on concentration increasement of nickel and tin compared to the previous report are investigated. Ni is successfully separated by a organic solvent and reduced to the metal powder whose concentration is over 98 %. Sn is separated by a selective solution method and its concentration is increased to 97.5 % by three consecutive solution and reduction process. Crystal structure, surface morphology and microstructure of the separated samples are studied.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.98-103
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• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.11
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• pp.1767-1778
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• 2010

This study investigates applying $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via electrospinning for the development of UV-protective materials. To fabricate uniform nanocomposite fibers, three types of $TiO_2$ nanoparticles were applied: powder, colloid, and $TiO_2$ coated polymer pellets. $TiO_2$/polyurethane (PU) and $TiO_2$/poly(vinyl alcohol) (PVA) nanocomposite fibers were electrospun and the morphology was examined using a field-emission scanning electron microscope and a transmission electron microscope. Layered fabric systems with electrospun $TiO_2$ nanocomposite fiber webs were developed at various concentrations of $TiO_2$ in a range of the web area density. The effects of $TiO_2$ concentration and web area density on UV-protective properties were examined. When $TiO_2$ colloid was added into a PVA polymer solution, uniform nanocomposite fiber webs in which $TiO_2$ particles were evenly dispersed were produced. Water-soluble PVA nanofiber webs were given a heat treatment to stabilize the electrospun PVA fibrous structure against dissolution in water. $TiO_2$/PVA nanoeomposite fiber webs with 2wt% $TiO_2$ and 3.0g/$m^2$ web area density exhibited an ultraviolet protection factor of greater than 50, indicating excellent UV protection.

• Journal of Pharmaceutical Investigation
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• v.33 no.1
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• pp.7-14
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• 2003

The PVP-based solid dispersion systems (SDs) containing lovastatin (LOS) and solubilizers (sodium lauryl sulfate, tween 80 and oleic acid) were prepared to enhance dissolution rate of practically water insoluble LOS using solvent evaporation method. Two different organic cosolvents either acetone/ethanol or acetonitrile/ethanol were used for the preparation of SDs. The LOS contents were highly decreased when acetone/ethanol cosolvents were used. The decrease of LOS contents was not caused by acetonitrile or acetone, based on HPLC data. The surface morphology as investigated by scanning electron microscope (SEM) and angle of repose as an index of flowability of SDs were highly dependent on the type and amount of solubilizers used. Based on differential scanning calorimetry (DSC) and X-ray powder diffraction data, the SDs made crystalline LOS into amorphous structure or partially eutectic mixtures. The simultaneous use of the solubilizers in SDs was also useful to increase dissolution rate of LOS in gastric or intestinal fluid. The SDs containing solubilizers reached 76% and 60% in gastric and intestinal fluid, respectively but the commercial tablet gave only less than 4%. These solubilizers in SDs could be also applicable for enhancing dissolution and bioavailability of poorly water-soluble drugs.

• The Journal of Korean Medicine
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• v.26 no.4
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• pp.31-38
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• 2005

Objectives: This study was conducted to investigate the effects of Morindae officinalis Radix (巴戟) on the spermatogenesis and antioxidant activities in the Sprague Dawley (SD) rat. Materials and Methods: We choose the 2-month-old SD rats, and administered the extract powder of Morindae officinalis Radix once in a day for 28 days. The control rats were administered normal water in the same way and duration. We observed changes of body weight, surgically isolated testis, epididymis, vascular gland and prostate gland before and after administration of Morindae officinalis Radix extracts in SD Rats. Also we compared the testicular tissue, especially seminiferous tubules between the control and treated groups by histochemical methods. In addition, we examined the total, normal, morphologic and motile sperm in the cauda epididymis, and the activity of catalase and peroxidase in the isolated testis tissue. Results: There was no significant difference between control and treatment groups in the body weight, testis, vascular and prostate gland, but the weight of epididymis showed significant difference in the control group. The concentration of total sperm, the motility and normality of spermatozoa was significantly different when compared with the control group, respectively. In the histological examination of testicular tissues, the tendency of increasement of angiogenesis between seminiferous tubules was observed. And the concentration of spermatogonia, primary and secondary spermatocyte and sperm were higher than that of control testicular tissues. Finally, the activity of catalase and peroxidase related inhibitory molecules of oxidation were slightly increased in the treatment group than those of control group. Conclusions: This study shows that Morindae officinalis Radix has the beneficial effect on the concentration, morphology and motility of sperm, the important factor in male fertility. We can suggest that Morindae officinalis Radix has an effect on the spermatogenesis in the SD rat.

• Korean Journal of Materials Research
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• v.17 no.6
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• pp.318-322
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• 2007

Porous ${\beta}-tricalcium$ phosphate $({\beta}-TCP)$ bioceramic was fabricated by pressureless sintering using commercial HAp and different volume percentages of PMMA powders (30-60 vol.%). The range of spherical pore size was about $200-250\;{\mu}m$ in diameter. By increasing the PMMA content, the number of pores and their morphology were dramatically changed as well as decreased the material properties. In case of using 60 vol.% PMMA content, network-type pores were found, due to the necking of the PMMA powders. The values of relative density, elastic modulus, bending strength and hardness of the 60 vol.% PMMA content sample, sintered at $1500^{\circ}C$, were about 46%, 22.2 GPa, 5MPa and 182 Hv respectively. Human osteoblast-like MG-63 cells and osteoclast-like Raw 264.7 cells were well grown and fully covered all of the porous ${\beta}-TCP$ bodies sintered at $1500^{\circ}C$.

• 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.