• 한국분말재료학회지
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• 제25권4호
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• pp.322-326
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• 2018

The hydrogen reduction behavior of $MoO_3-CuO$ powder mixture for the synthesis of homogeneous Mo-20 wt% Cu composite powder is investigated. The reduction behavior of ball-milled powder mixture is analyzed by XRD and temperature programmed reduction method at various heating rates in Ar-10% $H_2$ atmosphere. The XRD analysis of the heat-treated powder at $300^{\circ}C$ shows Cu, $MoO_3$, and $Cu_2MoO_5$ phases. In contrast, the powder mixture heated at $400^{\circ}C$ is composed of Cu and $MoO_2$ phases. The hydrogen reduction kinetic is evaluated by the amount of peak shift with heating rates. The activation energies for the reduction, estimated by the slope of the Kissinger plot, are measured as 112.2 kJ/mol and 65.2 kJ/mol, depending on the reduction steps from CuO to Cu and from $MoO_3$ to $MoO_2$, respectively. The measured activation energy for the reduction of $MoO_3$ is explained by the effect of pre-reduced Cu particles. The powder mixture, hydrogen-reduced at $700^{\circ}C$, shows the dispersion of nano-sized Cu agglomerates on the surface of Mo powders.

• 한국수산과학회지
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• 제42권4호
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• pp.395-398
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• 2009

This study was conducted to investigate the effects of supplemental medicinal herb mixture, laver powder and paprika powder in extruded pellet (EP) on growth and feed utilization of juvenile olive flounder. Triplicate groups of fish (average body weight of 19.6 g) were fed four experimental EPs containing 0.2% medicinal herb mixture (MHM), 1% laver powder (LP), 1% paprika powder (PP) and without supplementation (CON) for 9 weeks. Weight gain, daily feed intake, hepatosomatic index and condition factor were not influenced by dietary additives. Peed efficiency and protein efficiency ratio of flounder fed the diet containing laver powder were significantly higher than those of fish fed the medicinal herb mixture and paprika powder (P<0.05), but not significantly different from control group. The results of this study suggest that all tested additives in the dietary formulation did not affect growth and feed utilization of olive flounder.

• 한국분말재료학회지
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• 제5권1호
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• pp.64-70
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• 1998

Milling media of steel and partially stabilized zirconia(PSZ) were used to produce $Mo_3$Si by mechanical alloying(MA) of Mo-25.0at%Si elemental powder mixture. The effect of milling medium materials on MA of the powder mixture have been investigated by XRD and DTA. The reaction rate and the end-product noticeably depended upon the milling medium material. The formation of $Mo_3$Si and $Mo_5Si_3$phases by PSZ ball-milling took place after 15 hr of MA and was characterized by a slow reaction rate as Mo, Si, $Mo_5Si_3$ and $Mo_3$Si coexisted for a long period of milling time. The formation of a new phase by steel ball-milling, however, did not take Place even after 96 hr of MA. DTA and annealing results showed that $Mo_5Si_3$ and $Mo_3$Si were formed after heating the ball-milled powder specimens to different temperatures. At low temperatures, Mo and Si were transformed into $Mo_5Si_3$. At high temperatures, the formation of $Mo_3$Si can be partially attributed to the reaction, 7Mo+Si+$Mo_5Si_3$-.4$Mo_3$Si . The formation of $Mo_3$Si and Mo5Si3 phases by mechanical alloying of the powder mixture and the relevant reaction rate appeared to depend upon the milling medium material as well as the thermodynamic properties of the end-products.

• Preventive Nutrition and Food Science
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• 제9권4호
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• pp.346-351
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• 2004

This study was carried out to examine the antioxidant effects of a mixture of mulberry leaves and silkworm powder in plasma and liver of streptozotocin-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10 g were used and their diets were supplemented with $0.4\%$ (4 g/kg) of the mixtures. Experimental groups were diabetic rats without supplements (DM group) or with a combination of the supplements: $100\%$ mulberry leaves (M group), $25\%$ silkworm powder mixed with mulberry leaves (25SM group), $50\%$ silkworm powder mixed with mulberry leaves (50SM group), $75\%$ silkworm powder mixed with mulberry leaves (75SM group) or $100\%$ silkworm powder (100S group). The rats were fed experimental diets and water ad libitum. All animals were injected with streptozotocin at the $3^{rd}$ week for inducing diabetes and were sacrificed on $9^{th}$ day thereafter. Hepatic xanthine oxidase (XOD) activity significantly decreased in the mixture supplemented groups compared to the DM group. Hepatic superoxide dismutase (SOD) activity was not significantly different among any of the experimental groups, but glutathione peroxidase (GSH-px) activity increased in the mixture supplemented groups compared to the DM group. In particular, it was the highest in the 50SM group. The hepatic TBARS values were lower in all the mixture supplemented groups than in the DM group, and it was as lowest when ratio of mulberry leaves to silkworm powder was highest. Hepatic lipofuscin contents were similar with the TBARS value. In conclusion, the mixtures containing silkworm powder reduced oxidative damage by strengtbening the antioxidative system and suppressing oxidative stress in the STZ-induced diabetic rat. The 1:1 blend of silkworm powder and mulberry leaves was the most effective combination for antioxidant activity.

• 한국조리학회지
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• 제14권4호
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• pp.1-13
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• 2008

The antioxidant activity and quality characteristics of bread made from waxy black rice flour(WBRF) and green tea powder were investigated. The bread was manufactured with 1% of green tea powder and 10, 20, 30 or 40% of WBRF(w/w). The group of 40% of WBRF and green tea powder significantly showed the highest bread weight and volume. Lightness(L value) and yellowness(b value) decreased, but redness(a value) increased with increasing WBRF contents in mixture. Hardness, gumminess and chewiness were the lowest in the control group, but springiness was the lowest in the group of 40% of WBRF and 1% of green tea powder. The sensory scores of appearance, external and crumb color, grainy in the group of 40% of WBRF and 1% of green tea powder were the significantly lowest. Overall acceptabilities of the groups of 10% and 30% of WBRF with 1% of green tea powder were not significantly different from the control group. The group of 40% of WBRF and 1% of green tea powder showed the highest DPPH radical scavenging effect and TEAC content. Thus, if the mixture of green tea powder and WBRF would be used, it might be proper to use 1% of green tea powder and 10% of WBRF mixture considering the quality and antioxidant activity of bread.

• 한국조리학회지
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• 제6권3호
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• pp.281-289
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• 2000

By adding mushroom powder in baking white bread all the edible ingredients and numerous effectiveness of green tea can be consumed completely and the beautiful natural colors of green tea can result the variety of colors of cookies and breads. In this thesis, I used sensory evaluation and mechanical test to decide the appropriate amount of mushroom powder added in baking white bread among the ratios of 1%, 2%, 3%, 4%, 5% of mushroom powder relative to flour. I find the followings. In sensory evaluation. the color of white bread resulted from the addition of mushroom powder was most attractive in The 3% mixtures tasted most salty and other than this mixtures made no differences in salty tastes. The 3% mixture tasted most sweet and the same mixture resulted best in astringent taste. On the other hand, the overall test agreed almost with the sensory tests and there were some significant differences when p< 0.05. In summing up the above findings of our investigations, the 3% mixture of mushroom powder produces the best white Bread.

• 한국분말재료학회지
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• 제12권2호
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• pp.112-116
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• 2005

In the present study, the focus is on the analysis of carbothermal reduction of oxide powder prepared from waste WC/Co hardmetal by solid carbon under a stream of argon for the recycling of the WC/Co hard-metal. The oxide powder was prepared by the combination of the oxidation and crushing processes using the waste $WC-8 wt.\%Co$ hardmetal as the raw material. This oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and gases discharge of the mixture during carbothermal reduction was analysed using XRD and gas analyzer. The oxide powder prepared from waste $WC-8wt.\%Co$ hardmetal has a mixture of $WO_{3} and CoWO_{4}$. This oxide powder reduced at about $850^{\circ}C$, formed tungsten carbides at about $950^{\circ}C$, and then fully transformed to a mixed state of tungsten carbide (WC) and cobalt at about $1100^{\circ}C$ by solid carbon under a stream of argon. The WC/Co composite powder synthesized at $1000^{\circ}C$ for 6 hours from oxide powder of waste $WC-8wt.\%Co$ hardmetal has an average particle size of $0.3 {\mu}m$.

• 한국지반공학회논문집
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• 제26권2호
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• pp.55-62
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• 2010

폐타이어 분말 입경에 따른 폐타이어-저회 혼합토의 전단특성에 관한 연구를 수행하였다. 건조된 저회 중량을 기준으로 5개의 폐타이어 분말 함량(0%, 25%, 50%, 75%, 100%)과 3종류의 폐타이어 분말 입경(0.1mm~2.0mm, 0.9mm~5mm, 2mm~10mm)에 따라 공시체를 준비하였다. 직접전단시험을 수행한 결과 폐타이어-저회 혼합토의 역학적 특성은 폐타이어 분말 입경과 함량에 크게 의존하는 것을 알 수 있다. 폐타이어 분말 함량이 증가함에 따라 혼합토의 전단강도와 내부마찰각은 감소하나, 폐타이어 분말 입경이 커짐에 따라 입자간의 억물림 효과에 의해 전단강도와 내부마찰각은 증가하는 경향을 가진다.

• 한국자기학회지
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• 제5권5호
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• pp.687-689
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• 1995

Our team works on mixture of hard magnetic materials. As hard magnetic material we used mixture of powders: melt-spun ribbon Nd-Fe-B, ferrite and Alnico. Their different mixtures are basic material for dielectromagnets under our investigation. Main disadvantage of dielectromagnets with Nd-Fe-B alloy powder as a component is a low corrosion resistance. Protection against corrosion is covering dielectromagnets with metallic or organic coating film. The coating film protects dielectromagnets from free particles on the surface and low resistance for mechanical stresses too. The surface of dielectromagnets prepared from mixture of powders if formed by metallic particles - powder of Nd-Fe-B and Alnico, particles of oxide - powder of ferrite and particles of resin - bonding materials. Team work on technology of laying the metallic coating on dielectromagnets prepared from mixture of mentioned powders. Papers show the results of initial investigation on metallic coating technology. It shows influence of type and used technology of the metallic coating film on magnetic properties of dielectromagnets.

• 한국분말재료학회지
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• 제26권5호
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• pp.410-414
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• 2019

The hydrogen reduction behavior of the $CuO-SCo_3O_4$ powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and $SCo_3O_4$ to Co, respectively. The measured temperature and activation energy for the reduction of $SCo_3O_4$ are explained on the basis of the effect of pre-reduced Cu particles.