• Composites Research
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• v.37 no.3
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• pp.150-154
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• 2024

In this study, nanofibrillated cellulose was extracted from soybean hulls - a by-product of soybeans - and compared with soybean hull nanofibrillated cellulose obtained by using other nanofibrillated methods. Dry soybean hulls were ground into prepare micrometer-sized powders, from which microcellulose was isolated using NaOH and HCl. The nanometer-sized cellulose was successfully extracted through ultrasonic dispersion and ball milling. The soybean hull nanofibrillated cellulose exhibited a diameter of 60-100 nm and a length of 0.3-1.0 ㎛, which matches the diameter of soybean nanofibrillated cellulose made by other nanofibrillated methods but is significantly shorter in length.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.817-824
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• 1999

The $Al_2$$O_3$-SiC composite powder was prepared by Self-propagating High-Temperature Synthesis(SHS) process using $SiO_2$Al and C powders as raw material. The effects of the molar ratio in raw material, compaction pressure, initial temperature of reactants on the products and combustion process were studied. Self-propagating high temperature synthesis of $SiO_2$/Al/C system should be preheated above $400^{\circ}C$ owing to the low combustion temperature. As the result of the combustion reaction, the purity of final product became better than that of reactants. In this system, the optimum molar ratio of $SiO_2$:Al:C was 3.0:4.0:6.0. The free carbon was removed by roasting at $650^{\circ}C$ for 30min. In this study, pressureless sintering was very dffective both for controlling the disintegration of specimen with powder bed and for obtaining dense sintered-body at $1700^{\circ}C$. The sintered-body produced with hot-pressing was about 98% of the theoretical relative density.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.799-805
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• 2001

Two commercial alumina powders having different particle size of $0.5{\mu}m$ and 3${\mu}$m were presintered at 1120$^{\circ}$C for 2h and then lanthanum aluminosilicate glass was infiltrated at 1100$^{\circ}$C for up to 4h to obtain the densified glass-alumina composites. The effect of alumina particle size on packing factor, microstructure, wetting, porosity and pore size, and mechanical properties of the composite was investigated. The optimum mechanical properties and compaction behavior were observed for the 3${\mu}$m alumina particle dispersed composite. The 3${\mu}$m alumina particle size and distribution for he preform were within 0.1 to 48${\mu}$m and bimodal and random orientation. The strength and the fracture toughness of the composite having 3${\mu}$m alumina particles were 519MPa and $4.5MPa{\cdot}m^{1/2}$, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.173-180
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• 2004

Nano sized ZnO particle as 20-30nm applies for material, pigments, rubber additives, gas sensors, varistors, fluorescent substance as well as new material such as photo-catalyst, sensitizer, fluorescent material. ZnO with a particle size in the range 20-30nm has provided to be an excellent UV blocking material in the cosmetics industry, which can be used in sunscreen product to enhance the sun protection factor and natural makeup effect. But pure ZnO particles application limits for getting worse wearing feeling. We make high-functional inorganic-composite that coated with nano-ZnO on the plate-type particle such as sericite, boron nitride and bismuthoxychloride. In this experiment, we synthesized composite powder using hydrothermal precipitation method. The starting material was ZnCl$_2$ Precipitation materials were used hexamethylenetetramine(HMT) and urea. We make an experiment with changing as synthesis factors that are concentrations of starting material, precipitation materials, nuclear formation material, reaction time, and reaction temperature. We analyzed composite powder's shape, crystallization and UV-blocking ability with FE-SEM, XRD, FT-IR, TGA-DTA, In vitro SPF test. The user test was conducted by product's formulator. In the results of this study, nanometer sized ZnD was coated regardless of the type of plate-powder at fixed condition range. When the coated plate-powders were applied in pressed powder product, the glaze of powder itself decreased, but natural make-up effect, spreadability, and adhesionability were increased.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.315-321
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• 1999

Metal matrix composites have been extensively studied because of their excellent characteristics for structural application. $Al_2O_3$ and SiC have been used as a common reinforcement owing to their good mechanical properties. However the manufacturing cost of these ceramic reinforcement is expensive, so the use of the composites has been restricted to special purposes. In this study, we tested the application possibility as a reinforcement of $Al_2O_3$-TiC powder synthesized by SHS(Self-propagating High-temperature Synthesis) process to Al alloy matrix composite. Also, $Al_2O_3$ short fibers were added with the synthesized powders in order to apply to the Al matrix hybrid composites. Squeeze infiltration casting process was used to make the composite with 25vol% of reinforcement. Microstructure and crystal structure were examined by SEM, OM and XRD, also the mechanical properties were studied by the compressive test and wear test.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.6
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• pp.491-497
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• 2001

Polymethylmethacrylate(PMMA) is currently commonly used material for the reconstruction of bone defects and fixation of joint prosthetics following congenital and acquired causes. Although PMMA has widespread use, it does not possess the ideal mechanical characteristics with osteoconductivity and osteoinductivity required. In order to overcome these problem, addition of bovine bone drived defatting demineralized bone(BDB) powders to a PMMA bone cement was done for improvement of physical property and bone forming characteristics of composite. In order to investigate the influence of BDB reinforcement on the PMMA, we measured physical property of compressive, tensile, flexural strength, and scanning electron microscopic examinations. The results were obtained as follows: 1. The PMMA forms a solid cellular matrix with open cells about $100{\mu}m$ in variable size and incorporating BDB. BDB aggregates inside the cells form a porous network that is accessible from the outer surface. 2. The physical properties were compressive strength of mean $22.74{\pm}1.69MPa$, tensile strength of mean $22.74{\pm}1.69MPa$, flexural strength of mean $77.53{\pm}6.93MPa$. Scanning electron microscopic examinations were revealed that there was DBD particles form a highly porous agglomerates. BDB can be added PMMA in the form of dried powders, the composites are applicable as bone substitutes. BDB and PMMA mixture is shown to produce a class of composites that due to their microstructure and improved mechanical properties may be suitable for application as bone subsitutes. The mechanical and material properties of the BDB-PMMA bone substitute composites are competitive with those properties of a porous ceramic matrix of other hydroxyapatite and with those of natural bones.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.11-18
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• 2016

This study focused on examining the possibility for recycling of Fe-Si electric sheet. We manufactured Fe-6.5Si mother alloy using by Fe-Si electric sheet scrap for transformer core materials. And then, soft magnetic alloy powder which diameter and shape were $45{\sim}150{\mu}m$ and sphere type was prepared by gas atomization process. As we compared to commercial Fe-6.5Si powder, its diameter distribution and microstructure of recycled powder was a similar. To investigate the possibility of reusing the soft magnetic composite sheet for electronics, recycled powder was treated to have a high aspect ratio (AR), and we finally obtained the 65~66 AR and $2.3{\mu}m$ thickness powder. To release the residual stress of powder, heat treatment was conducted under $300{\sim}400^{\circ}C$, $N_2$ gas. And then, soft magnetic sheet was made by tape casting process using by those powders. After the density and permeability of tape was measured, and we confirmed that the recycled Fe-Si electric sheet scrap was possible to reuse the soft magnetic materials of electronics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.127-132
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• 2014

$Y_2O_3$-BN ceramic composites were fabricated from the slurries of yttria powder with average particle size of 3~10 ${\mu}m$. The slurry was fabricated by mixing PVA binder, NaOH for Ph control, PEG, BN powder and $Y_2O_3$ powder. The mixed $Y_2O_3$ powders were obtained by spray drying process from the slurry. The $Y_2O_3$-BN composite specimen was shaped in size of ${\O}14mm$ and then sintered at $1550^{\circ}C$ and $1600^{\circ}C$, respectively. The characteristics, microstructure, purities, densities, bulk resistance, thermal expansion, hardness and plasma resistance of the $Y_2O_3$-BN composites were investigated with the function of BN contents and sintering temperature.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.69-74
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• 2006

Thick film $H_2$ sensors were fabricated using $SnO_2$ loaded with $Ag_2O$ and $PtO_x$. The composition that gave the highest sensitivity for $H_2$ was in the weight% ratio of $SnO_2 : PtO_x : Ag_2O$ as 93 : 1 : 6. The nano-crystalline powders of $SnO_2$ synthesized by sol-gel method were screen printed with $Ag_2O$ and $PtO_x$ on alumina substrates. The fabricated sensors were tested against gases like $H_2$, $CH_4$, $C_3H_8$, $C_2H_5OH$ and $SO_2$. The composite material was found sensitive against $H_2$ at the working temperature $130^{\circ}C$, with minor interference of other gases. The $H_2$ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on $SnO_2-Ag_2O-PtO_x$ system exhibited the high performance, high selectivity and very short response time to $H_2$ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of $H_2$.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.160-166
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• 2007

Response surface methodology (RSM) was used for the optimization of the baking process of cookies made with onion powders (onion cookie). Experiments were carried out according to a central composite design, selecting onion powder content $(1.15{\sim}8.86%)$ and baking temperature $(155.9{\sim}184.1^{\circ}C)$ as independent variables and pH, titratable acidity, moisture content, density, spread factor, CIE color parameters $(L^{\ast}-$, $a^{\ast}-$, and $b^{\ast}-values)$, and hardness as response variables. pH decreased with increasing amount of onion powder and baking temperature. Moisture content also decreased as the baking temperature increased. $L^{\ast}-$ and $b^{\ast}-values$ decreased but $a^{\ast}-values$ increased with increasing onion content and baking temperature. Most polynomial models developed by RSM were highly effective to describe the relationships between the studied factors and the responses. Overall optimization, conducted by overlaying the contour plots under investigation, was able to point out the optimal range of the independent variables within which the six responses were simultaneously optimized. The point chosen as representative of this optimal region corresponded to 4.01% onion powder content and $161.84^{\circ}C$ baking temperature. The predicted dependent or response values in the optimal region were: pH＝6.87, moisture content＝2.77%, $L^{\ast}-value＝68.45$, $a^{\ast}-value＝1.98$, $b^{\ast}-value＝34.64$, and spread factor＝9.41.