• Title/Summary/Keyword: W substitution

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Effects of Partial Substitution of W for Ti in Titanium Dioxide

  • Lee, Eun-Seok
    • Transactions on Electrical and Electronic Materials
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    • v.12 no.2
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    • pp.68-71
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    • 2011
  • [ $Ti_{1-x}W_xO_{2-y}$ ]solid solutions with compositions of x = 0.01(TW-1), x = 0.02(TW-2), x = 0.03(TW-3) and x = 0.04(TW-4) were prepared at 1,073 K in air under atmospheric pressure. All the solutions exhibited tetragonal symmetries. Nonstoichiometric chemical formulas have been obtained from oxidation-reduction titration and the partial substitution of $W^{6+}$ ions mainly caused the formation of $Ti^{3+}$ ion, rather than oxygen excess. Resistivities of the samples were highly dependent on humidity. The increase of the W amount resulted in an increase of $Ti^{3+}$ content, decrease of resistivity values and finally degradation of photocatalytic activities.

An Experimental Study on the Quality Properties of High Strength Concrete by the Replacement Ratio SFFB as Substitutes of Silica-fume (실리카 흄 대체재로 활용 가능한 SFFB의 치환율에 따른 고강도 콘크리트의 품질특성에 관한 실험적 연구)

  • Lim, Byung-Hoon;Lee, Sang-Soo;Yun, Hyun-Do;Yoon, Gil-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.5
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    • pp.87-92
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    • 2010
  • This study set up 25, 35% for silica fume, SFFB's 2 level and water-combination material ratio, silica fume 10% for substitution ratio, and 4 level of SFFB 5, 10, 15(%) in order to compare and analyze the quality characteristic of ultra high strength concrete according to the substitution ratio of silica fume free binder (SFFB) that can be utilized as a substitute material for silica fume. As a result of an experimentation, the lower water-combination material ratio was, the higher addition ratio of high performance water-reducing agent for securing target liquidity increased, and it indicated the tendency that addition ratio of high performance water-reducing agent decreases because of material characteristic that SFFB has a lower absorptiveness than silica fume. The best strength was shown when SFFB substitution ratio is 10% at compressive strength and when substitution ratio is 15% at tensile strength, and it was indicated that at autogenous shrinkage contraction decreases compared to Plain(SF) regardless of substitution ratio of W/B and SFFB.

Reactioin Characteristics of the Sm2Fe17-xGax(x0, 2) Alloy with Hydrogen and Methane Gas

  • Shon, S.W;Kwon, H.W
    • Journal of Magnetics
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    • v.4 no.4
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    • pp.123-127
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    • 1999
  • The Ga-stabilised $Sm_2Fe_{17-}$type alloy can hardly be disproportionated under ordinary HDDR condition. The HDDR characteristics of Ga-substituted $Sm_2Fe_{17-}$type alloy were examined, and, in particular, the effect of particle size on the disproportionation of the Ga-substituted alloy was investigated in detail. The reaction characteristics of the $Sm_2Fe_{17-}$type alloys with or without Ga-substitution with methane (CH4) gas are also examined. The Ga-stabilised $Sm_2Fe_{17-}$type alloy was able to be disproportionated significantly on heating up to 80$0^{\circ}C$ under hydrogen with normal pressure. The particle size influenced significantly on the disproportion-ation of the Ga-substitute alloy, and the materials with finer particle size (<40 ${\mu}{\textrm}{m}$) was fully disproportionated on heating up to around 80$0^{\circ}C$ under hydrogen gas with normal pressure. The Ga-substituted alloy has a very sluggish recombination kinetics with respect to the alloy without Ga-substitution. The $Sm_2Fe_{17}C_{x-}$type carbide was stabilised significantly by the Ga-substitution for Fe in the parent alloy. While the $Sm_2Fe_{17}C_x$ was disproportionated below 80$0^{\circ}C$ the Ga-stabilised $Sm_2Fe_{14}Ga_2C_x$ carbide remained intact even on heating up to 80$0^{\circ}C$.

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Piezoelectric and Electric Field Induced Strain Properties of PMW-PNN-PZT Ceramics with the Substitution of Ba (Ba 치환에 따른 PMW-PNN-PZT 세라믹스의 압전 및 전계유기왜형 특성)

  • 윤광희;김규수;최병수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.1
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    • pp.20-25
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    • 2001
  • To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

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Effect of Co-Substitution on the Crystallization and Magnetic Properties of a Mechanically Milled Nd15(Fe1-xCox)77B8 (x=0-0.6) Alloy

  • Kwon, H.W.;Yang, C.J.
    • Journal of Magnetics
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    • v.7 no.4
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    • pp.143-146
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    • 2002
  • Mechanical milling technique is considered to be a useful way of processing the fine Nd-Fe-B-type powder with high coercivity. In the present study, phase evolution of the $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ (x=0-0.6) alloys during the high energy mechanical milling and annealing was investigated. The effect of Co-substitution on the crystallization of the mechanically milled $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ amorphous material was examined. The Nd-Fe-B-type alloys can be amorphized completely by a high-energy mechanical milling. On annealing of the amorphous material, fine $\alpha$-Fe crystallites form first from the amorphous. These fine $\alpha$-Fe crystallites reacts with the remaining amorphous afterwards, leading to crystallization to $Nd_2Fe_{14}$B phase. The Co-substitution for Fe in $Nd_{15}(Fe_{1-x}Co_{x})_{77}B_{8}$ ($\mu$x=0∼0.6) alloys lower significantly the crystallization temperature of the amorphous phase to the $Nd_2Fe_{14}$B phase. The mechanically milled and annealed $Nd_{15}Fe_{77}B_8$ alloy without Co-substitution exhibits consistently better magnetic properties with respect to the alloys with Co-substitution.

Effects of red glasswort as sodium chloride substitute on the physicochemical properties of pork loin ham

  • Jeong, Tae-Jun;Kim, Tae-Kyung;Kim, Hyun-Wook;Choi, Yun-Sang
    • Asian-Australasian Journal of Animal Sciences
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    • v.33 no.4
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    • pp.662-669
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    • 2020
  • Objective: This study was conducted to evaluate the effect of red glasswort (RG) (Salicornia herbacea L.) curing on the physicochemical, textural and sensory properties of cooked pork loin ham (M. longissimus thoracis et lumborum). Methods: All treatments were cured with different salt and RG powder levels. RG0 treatment was prepared with only 4% NaCl (w/w) as a control, and RG25, 3% NaCl:1% RG (w/w); RG50, 2% NaCl:2% RG (w/w); RG75, 1% NaCl:3% RG (w/w); RG100, 0% NaCl:4% RG (w/w) treatments were prepared sequentially. All samples were individually vacuum packaged in polyethylene bags and stored for 7 d at 3℃±1℃. Results: The results showed that as the rate of RG substitution increased, pH value, redness, myofibrillar protein solubility, and myofibrillar fragmentation index increased (p<0.05), but salt concentration and shear force decreased (p<0.05). However, there were no significant differences in cooking loss and moisture content. In terms of sensory evaluation, RG100 exhibited higher scores in tenderness and juiciness than RG0 (p<0.05). Conclusion: The partial substitution of NaCl by RG could improve the physicochemical properties, textural and sensory characteristics of cooked pork loin. Therefore, it is suggested that RG as a natural salt replacer could be an effective ingredient for developing low-sodium cured hams.

Preparation of Soy Yogust Using Isolated Soybean Protein and Whey Powder (분리대두단백과 유청분말을 사용한 대두 요구르트의 제조에 관한 연구)

  • 장재권;윤승헌
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.26 no.6
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    • pp.1128-1134
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    • 1997
  • Lactobacillus helveticus was inoculated to the fermentation liquid containing skin milk powder(SMT) plus soymilk, SMP plus isolated soybean protein(ISP), SMP plus ISP plus whey powder(WP) to increase the nutritional and economic value of commercial soy yogurt. The yogurt fermented with soymilk and SMP showed the lower acid production than of SMP and had significant beany flavor in the product. The yogurt prepared with ISP and SMP showed the higher cell number and lower acid production than that of SMP. Also, the partial substitution of SMP with ISP over 6%(w/w) produced less acceptable product due to gel production. The yogurt prepared by the partial substitution of SMP with ISP, WP and SMP showed the higher cell number and lower acid production than that of SMP and not bring about gel formation unlike the case of ISP. Sensory properties of yogurt substituted SMP with ISP and WP(38:62 mixture) below 4% were not significantly different from that of SMP and the sample containing the mixture over 6% and 0.067% artificial flavor showed lower sensory score due to beany taste than that of SMP. But increase of yogurt flavor up to 0.1% resulted in significantly high score in organoleptic acceptability. The separation of water occured in yogurt prepared by the combined mixture of ISP, WP and SMP, and this problem could be resolved by addition of Na-alginate and PGA at the concentration of 0.1%(w/w).

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An Experimental Study on the Flow Characteristics of Mortar using the Blast-Furnace Slag Sand (서냉슬래그 모르터의 FLOW특성에 관한 연구)

  • 임남기;이종균;김성식;김종락;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10c
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    • pp.54-59
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    • 1998
  • This experimental Study presents the flow properties of mortar Using the Blast-furnace Slag Sand. It gives following result. The substitution rate is inversely proportional to flow. But W/C ratio is directly proportional to flow. Consequently Flow characteristics of the Blast-furnace mortar is simillar to the river sand mortar.

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A Study on CO Substitution of Group 6 Metal Carbonyls by Using Phase Transfer Catalyst(2) (상이동촉매에 의한 GROUP 6 금속카르보닐의 CO 치환에 관한 연구(2) : 반응시간과 촉매량에 의한 영향)

  • Yang, Hyun-Soo;Park, Ha-Seon
    • Applied Chemistry for Engineering
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    • v.3 no.3
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    • pp.407-411
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    • 1992
  • The effects of phase transfer catalyst was studied on the substitution of CO ligand of $Mo(CO)_6$ [M=Cr, Mo, W] with two electron-pairs donating ligands, 2, 2'-bipyridine and 2, 2'-biquinoline. The change of product yield, $M(CO)_4(L)_2$, was discussed according to reaction time, mole composition of $M(CO)_6$, and type of ligand.

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