• Korean Journal of Materials Research
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• v.11 no.5
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• pp.393-397
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• 2001

Fer the purpose of improving ductility of $Al_3$Ti intermetallic compound has potential to industrial application, we investigated formation behavior of cubic Ll$_2$ structure and effect of Mn addition. Nanocrystalline cubic Ll$_2$Al$_3$Ti intermetallic compound, has 10nm size of grain, was fabricated by mechanical alloying for 20hr at the composition of Al-8Mn-25Ti. Ternary cubic Ll$_2$Al$_3$Ti, added Mn, did not showed phase transformation from Ll$_2$ to D0$_{23}$ or D0$_{22}$ unlike binary cubic Ll$_2$Al$_3$Ti and maintained Ll$_2$ structure.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1104-1109
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• 2001

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+}$$\delta$/ high $T_{c}$ superconductors containing As as an additive were fabricated by a solid-state reaction method. Samples with Ag of 10wt%, 30 wt% and 50 wt% each were sintered at 86$0^{\circ}C$~875$^{\circ}C$ for 24 hours. The structural characteristics, critical temperature and grain size with respect to Ag contents were analyzed by XRD(X-ray Diffraction) and SEM(Scanning Electron Microscope), respectively. As Ag contents increased, XRD peaks of g in Bi-2223 phase superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.increased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.396-403
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• 1995

Eightly nine common Korean foods were analyzed by the enzymatic-gravimetric method developed by Prosky et al. and adopted by AOAC to determine total dietary fiber(TDF) content. The average TDF content of the foods analyzed was 4.78${\pm}$3.55% for cereal and grain products, 2.56${\pm}$1.65% for potatoes and starches, 1.94${\pm}$0.77% for sugar and sweets, 10.81${\pm}$6.57% for pulse and pulse products, 9.70${\pm}$5.92% for nuts and seeds, 15..38${\pm}$15.76% for seasonings, and 4.98${\pm}$4.35% for beverages. The foods containing the highest TDF values in the food groups were whole grain barley(17.88%) in cereals, yellow soybean(21.05%) in pulses, black sesame(21.34%) in nuts and seeds, and red pepper powder(39.37%) in seasonings except San Cho powder(52.43%). TDF content of rice, the main staple food of Korea, was 2.75% for brown rice and 0.96% for well-milled rice. The TDF value of the foods analyzed ranged from 0.12 to 23.4 times that fo crude fiber reported in the Korean food composition tables. When we consider dietary fiber contents of foods and food consumption patterns together, it is recommended to consume brown rice instead of well-milled rice and increase the consumption of minor cereals and pulses to raise dietary fiber intake.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.49-49
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• 2008

ZnO-based varistors have been widely used for voltage stabilization or transient surge suppression in electric power systems and electronic circuits. Recently, It has reported that the varistor behavior with nonlinear coefficient of 6~17 in Mn-doped ZnO. In this study we have chosen the composition of ZnO-$TeO_2-Mn_3O_4$ (ZTM) system to the purpose of whether varistor behavior appeared in doped ZnO by the solid state sintering or not. We investigated the sintering and electric properties of 0.5~3.0 at% Mn doped ZnO-1.0 at% $TeO_2$ system. Electrical properties, such as current-voltage (I-V), capacitance-voltage (C-V), and impedance spectroscopy were conducted. $TeO_2$ itself melts at $732^{\circ}C$ in air but forms the $ZnTeO_3$ phase with ZnO as increasing temperature and therefore retards the densification of ZnO to $1000^{\circ}C$. The average grain size of sintered samples was at about $3{\mu}m$ and decreased with increasing Mn contents. It was found that a good varistor characteristics were developed in ZTM system sintered at $1100^{\circ}C$ (nonlinear coefficient $\alpha$ ~ 60). The results of C-V characteristics such as barrier height ($\Theta$), donor density ($N_d$), depletion layer (W), and interface state density ($N_t$) in ZTM ceramics were $4\times10^{17}cm^{-3}$, 0.7 V, 40 nm, and $1.6\times10^{12}cm^{-2}$, respectively. It will be discussed about the stability and homogeneity of grain boundaries using distribution parameter ($\alpha$) simulated with the Z(T)"-logf plots in ZTM system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.661-664
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• 1999

The piezoelectric properties and the doping effect of Nb$_2$O$_{5}$ for 0.95 PbZr$_{x}$ Ti$_{1-x}$ -O$_3$+0.05 Pb(Mnsub 1/3/Nb$_{2}$3/)O$_3$ compositions have been investigated. In the composition of 0.95PbZr$_{0.51}$Ti$_{0.49}$O$_3$+0.05Pb(Mn$_{1}$3/Nb/syb 2/3/)O$_3$ the values of k$_{p}$ and $\varepsilon$$_{33}$ $^{T}$ are maximized, but Q$_{m}$ was minimized (k$_{p}$ =0.57, Q$_{m}$ =1550). The grain size was suppressed and the uniformity of grain was improves with doping concentration of Nb$_2$O$_{5}$ far 0.95PbZr$_{0.51}$Ti$_{0.49}$O$_3$+0.05Pb(Mn$_{1}$3/Nb/syb 2/3/)O$_3$. sample. The values of k$_{p}$ first decreased slightly when a small amount of Nb$^{5+}$ is doped and then decreased when the Nb$^{5+}$ concentration is further increased. The Q$_{m}$ . OR the Other hand. increased monotonously with doping concentration of Nb$_2$O$_{5}$ .{5}$ . .

• Corrosion Science and Technology
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• v.3 no.5
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• pp.198-208
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• 2004

Although there has been no general agreement on the mechanism of primary water stress corrosion cracking (PWSCC) as one of major degradation modes of Ni-base alloys in pressurized water reactors (PWR's), common postulation derived from previous studies is that the damage to the alloy substrate can be related to mass transport characteristics and/or repair properties of overlaid oxide film. Recently, it was shown that the oxide film structure and PWSCC initiation time as well as crack growth rate were systematically varied as a function of dissolved hydrogen concentration in high temperature water, supporting the postulation. In order to understand how the oxide film composition can vary with water chemistry, this study was conducted to characterize oxide films on Alloy 600 by an in-situ Raman spectroscopy. Based on both experimental and thermodynamic prediction results, Ni/NiO thermodynamic equilibrium condition was defined as a function of electrochemical potential and temperature. The results agree well with Attanasio et al.'s data by contact electrical resistance measurements. The anomalously high PWSCC growth rate consistently observed in the vicinity of Ni/NiO equilibrium is then attributed to weak thermodynamic stability of NiO. Redox-induced phase transition between Ni metal and NiO may undermine the integrity of NiO and enhance presumably the percolation of oxidizing environment through the oxide film, especially along grain boundaries. The redox-induced grain boundary oxide degradation mechanism has been postulated and will be tested by using the in-situ Raman facility.

• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.61-75
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• 2011

Mantle-derived xenoliths, corresponding to spinel harzburgite and lherzolite in alkali basalts from Jeju Island, are metasomatized to various extents. They contain distinctive secondary orthopyroxene, forming corona or poikilitic textures. It clearly indicate that this secondary orthopyroxene has been produced at the expense of olivine along the grain boundaries and margins, suggesting silica-enriched metasomatic melt infiltrated through grain boundaries. Based on the geotectonic characteristics of Jeju Island and textural characteristics and major elements composition of mantle xenoliths, it is suggested that the silica-enriched melt/fluid could have derived from the ancient subducted slab, possibly in the mantle wedge, implying that the high $SiO_2$ activity in the lithospheric upper mantle beneath Jeju Island at that time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.19-23
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• 2018

In a Pb-included piezoelectric composition, $Sr_yPb_{1-y}[(Zn_{1/3}Nb_{2/3})_x-(Ni_{1/3}Nb_{2/3})_{0.2}-(Zr_{0.46}Ti_{0.54})_{0.8-x}]O_3$ was selected in order to attain high piezoelectric properties. According to the PZN ratio (x) and the amount of Sr doping (y), the crystal structure, microstructure and piezoelectric properties were measured and evaluated. In the case of Sr 4 mol% doping, the piezoelectric properties were the highest for a PZN ratio of 0.1. In this condition, the grain size was larger and the intensity was higher. With the PZN ratio fixed and varying the Sr doping, the piezoelectric properties increased until 10 mol% doping and then decreased for over 12 mol% doping. In the case of x＝0.1 and y＝10 mol%, the best piezoelectric properties were obtained, i.e., $d_{33}=660pC/N$ and $k_p=68.5%$, and these values seem to be related to the grain size and crystal structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.403-406
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• 2000

The piezoelectric properties and the doping effect of N $b_2$ $O_{5}$ and Mn $O_2$for 0.95PbZ $r_{x}$ $Ti_{x}$ $O_3$+0.05Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$ compositions have been investigated. In the composition of 0.95PbZ $r_{0.54}$ $Ti_{0.46}$ $O_3$+0.05Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$the Values Of $k_{p}$ find and $\varepsilon$$_{33}$ $^{T}$ are maximized, but $Q_{m}$ Was minimized ( $k_{p}$ =0.51, $Q_{m}$ =1750). The grain size was suppressed and the uniformity of grain was improved with doping concentration of N $b_2$ $O_{5}$ for 0.95PbZ $r_{0.54}$ $Ti_{0.46}$ $O_3$+0.005Pb(M $n_{0.42}$ $W_{0.26}$S $b_{0.32}$) $O_3$sample. The values of $k_{p}$ increased and the values of $Q_{m}$ slightly decreased when 0.5 wt% of N $b_2$ $O_{5}$ is doped. And the values of $k_{p}$ was the same formation of the N $b_2$ $O_{5}$ dopant when 0.5 wt% of M $n_2$ $O_{5}$ is doped. But the values of $Q_{m}$ was deeply decreased when 0.5 wt% of Mn $O_2$is doped. As a experiment results under high electric field driving, this piezoelectric ceramics are very stable. Conclusively, piezoelectric ceramic compsiton investigated at this paper is suitable for application to high power piezoelectric devices.. devices..ices.. devices..

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.5
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• pp.852-856
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• 2004

This study was conducted to determine on the proximate analysis and the several structural carbohydrate for 11 kinds of new vegetables. The samples were dried at 6$0^{\circ}C$ for 24 hrs and ground to pass a 0.5 mm screen. The crude protein and crude fat contents of new vegetables were 2∼3 times higher than those of grain as dry matter basis. However the crude ash content of new vegetables was 7 times higher than that of grain. Total dietary fiber was ranged from 32.61% (Costamary) to 41,22% (Treviso) as dry matter basis. Insoluble dietary fiber was ranged from 21.58％ (Red leaf beet) to 28.95％ (Treviso) as dry matter basis. Soluble dietary fiber was ranged from 6.60% (Nakai) to 14.70% (Common danelion) as dry matter basis. Total carbohydrates was ranged from 73.62% (Salad bowl) to 36.30% (Red leaf beet) as dry matter basis. Neutral detergent fiber was ranged from 48.83% (Nakai) to 29.60% (Red leaf beet) as dry matter basis. Acid detergent lignin was ranged from 27.65% (Salad bowl) to 2.92% (Corn salad) as dry matter basis. Hemicellulose was ranged from 22.55% (Nakai) to 2.15% (Salad bowl).