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Composition-property Relationships of Enamel Glass for Low Carbon Steel

  • Kang, Eun-Tae;Kim, Jong-Po;Cho, Yong-Hyun;Park, Seon-Mi
    • Journal of the Korean Ceramic Society
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    • v.50 no.3
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    • pp.186-194
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    • 2013
  • The relationship between composition and properties of enamel glass was investigated by introducing a mixture design. The enamel glass was manufactured by mixing various components under the following constraints: $45{\leq}SiO_2{\leq}55$, $10{\leq}B_2O_3{\leq}18$, $6{\leq}Na_2O{\leq}15$, $1{\leq}Li_2O{\leq}6$, $5{\leq}K_2O{\leq}10$, $0{\leq}TiO_2{\leq}8$, $0{\leq}ZrO_2{\leq}8$, 13.3MO (mol %). A mathematical model for the calculation of some properties of enamel glasses as a function of their composition was developed by the experimental statistical method. The results showed that the proposed model with the experimental measurement were in good agreement and the mixture experimental design was an effective method for optimizing the composition of the enamel glass with respect to its properties.

X-ray and dielectric study of the phase transition in PbFe1/2Nb1/2O3-PbCo1/2W1/2O3 ceramics

  • Park, Yung;Lee, Hong-Min;Kim, Ho-Gi
    • Proceedings of the KIEE Conference
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    • 1997.07d
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    • pp.1239-1243
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    • 1997
  • A phase analysis in the solid solution of (1-x) PbFe1/2Nb1/2O3-xPbCo1/2W1/2O3 is conducted by dielectric properties, heat capacity and E-P hysteresis at x=0.1 interval. Lattice constants and superlattice intensity are analyzed by the x-ray diffraction, and the temperature - composition phase diagram is determined. The system is found to form a solid solution of perovskite structure throughout the entire composition range, but the nature of phase transitions changes from ferroelectric-paraelectric for $0{\leq}x{\leq}0.5$ to antiferroelectric-paraelectric for $0.6{\leq}x{\leq}1.0$. The transitions of ferroelectric-paraelectric and antiferroelectric-paraelectric for $0.2{\leq}x{\leq}0.5$ and for $0.6{\leq}x{\leq}0.8$, respectively, are diffuse, while those of the ferroelectric-paraelectric and the antiferroelectric-paraelectric for $0.0{\leq}x{\leq}0.1$ and $0.9{\leq}x{\leq}1.0$, respectively are sharp.

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Magnetic Properties of Cu-Zn Ferrites (Cu-Zn 훼라이트의 자기적 성질)

  • 이충섭;이찬영;김철성;지상희
    • Journal of the Korean Magnetics Society
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    • v.3 no.1
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    • pp.18-22
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    • 1993
  • The cationic distributions and magnetic properties of $Cu_{x}Zn_{1-x}Fe_{2}O_{4}(0{\leq}x{\leq}1)$ have been studied by X-ray diffraction and $M\"{o}ssbauer$ spectroscopy. The crystal structures are cubic spinels in the range $0{\leq}x{\leq}0.9$. The ionic distribution of ${(Zn_{1-x}Fe_{x})}_{A}{[Zn_{x}Fe_{2-x}]}_{B}O_{4}$, where x=0.1. The distribution of $Fe^{3+}$ ions was extracted from the $M\"{o}ssbauer$ spectra below Curie temperature in the whole range $0{\leq}x{\leq}1$. The number of $Fe^{3+}$ ions in the tetrahedral sites and Curie temperature of Cu-Zn ferrite increase with increasing Cu-concentration.

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Prediction of Very High Critical Heat Flux for Subcooled Flow Boiling in a Vertical Round Tube (수직 원형관에서 서브쿨비등시 매우 높은 임계열유속의 예측)

  • Kwon, Young-Min;Hahn, Do-Hee
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.288-293
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    • 2001
  • A critical heat flux (CHF) prediction method using an artificial neural network (ANN) was evaluated for application to the high-heat-flux (HHF) subcooled flow boiling. The developed ANN predictions were compared with the experimental database consisting of a total of 3069 CHF data points. Also, the prediction performance by the ANN was compared with those by mechanistic models and a look up table technique. The parameter ranges of the experimental data are: $0.33{\leq}D{\leq}37.5mm$, $0.002{\leq}L{\leq}4m$, $0.37{\leq}G{\leq}134Mg/m^2s$, $0.1{\leq}P{\leq}20MPa$, $50\leq{\Delta}h_{sub,in}\leq1660kJ/kg$, and $1.1{\leq}q_{CHF}\leq276MW/m^2$. $276MW/m^2$. It was found that 91.5% of the total data points were predicted within $a{\pm}20%$ error band, which showed the best prediction performance among the existing CHF prediction methods considered.

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SOME APPLICATION OF THE UNION OF TWO 𝕜-CONFIGURATIONS IN ℙ2

  • Shin, Yong-Su
    • Journal of the Chungcheong Mathematical Society
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    • v.27 no.3
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    • pp.413-418
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    • 2014
  • It has been proved that the union of two linear star-configurations in $\mathbb{P}^2$ of type s and t for either $3{\leq}t{\leq}10$ or $\(\frac{t}{2}\)-1{\leq}s$ with $3{\leq}t$ has maximal Hilbert function. We extend the condition to $\[\frac{1}{2}\(\frac{t}{2}\)\]{\leq}s$, so that it is true for either $3{\leq}t{\leq}10$ or $\[\frac{1}{2}\(\frac{t}{2}\)\]{\leq}s$ with $3{\leq}t$, which extends the result of [6].

APPROXIMATE CONTROLLABILITY FOR NONLINEAR INTEGRODIFFERENTIAL EQUATIONS

  • Choi, J.R.;Kwun, Y.C.;Sung, Y.K.
    • The Pure and Applied Mathematics
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    • v.2 no.2
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    • pp.173-181
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    • 1995
  • Our objective is to investigate approximate controllability of a class of partial integrodifferential systems. This work continuous the investigations of [8]. As a model for this class one may take the equation $\frac{\partialy(t,\;\xi)}{\partialt}\;=\;\frac{\partial}{\partial\xi}(a(t,\;\xi\frac{\partialy(t,\;\xi)}{\partial\xi})\;+\;F(t,\;y(t\;-\;r,\;\xi),\;{{\int_0}^t}\;k(t,\;s,\;y(s\;-\;r,\;\xi))ds)\;+\;b(\xi)u(t),\;0\;\leq\;\xi\;\leq\;1,\;\leq\;t\;\leq\;T$ with initial-boundary conditions y(t,\;0)\;=\;y(t,\;1)\;=\;0,\;0\;\leq\;t\;\leq\;T,\;y(t,\;\xi)\;=\;\phi(t,\;\xi),\;0\;\leq\;1,\;-r\;\leq\;t\;\leq\;0$.(omitted)

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Determination of Nonstoichiometry$(\delta)$and Phase Stability Region of $(Mg_{0.29}Fe_{0.71})_{3-}\deltaO_4$ by a Coulometric Titration Method (전하적정법에 의한 $(Mg_{0.29}Fe_{0.71})_{3-}\deltaO_4$ 훼라이트의 Nonstoichiometry$(\delta)$와 상안정 영역 결정)

  • 강선호;유한일;강대석;유병두
    • Journal of the Korean Ceramic Society
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    • v.31 no.12
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    • pp.1491-1500
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    • 1994
  • Nonstoichiometry($\delta$) and the phase stability region of a ferrite spinel (Mg0.29Fe0.71)3-$\delta$O4 have been investigated by a coulometric titration method as a function of temperature(T) and oxygen partial pressure(Po2). It has been found that the spinel is thermodynamically stable in the ranges -8.0$\leq$log(PO2/atm)$\leq$-2.4, -7.0$\leq$log(PO2/atm)$\leq$-1.7 respectvely at 100$0^{\circ}C$. The nonstoichiometry extends over the ranges of -0.004$\leq$$\delta$$\leq$0.007, -0.008$\leq$$\delta$$\leq$0.006, -0.033$\leq$$\delta$$\leq$0.004 at 100$0^{\circ}C$, 120$0^{\circ}C$, respectvely. The observed PO2-dependence of $\delta$ suggests that the majority ionic defects are cation interstitials in the low PO2 region and cation vacancies in the high PO2 region.

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ON THE HILBERT FUNCTION OF THE UNION OF TWO LINEAR STAR-CONFIGURATIONS IN $\mathbb{P}^2$

  • Shin, Yong Su
    • Journal of the Chungcheong Mathematical Society
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    • v.25 no.3
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    • pp.553-562
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    • 2012
  • It has been proved that the union of two linear star-configurations in $\mathbb{P}^2$ of type $t{\times}s$ for $3{\leq}t{\leq}9$ and $3{\leq}t{\leq}s$ has generic Hilbert function. We extend the condition to $t$ = 10, so that it is true for $3{\leq}t{\leq}10$, which generalizes the result of [7].

AN INEQUALITY OF SUBHARMONIC FUNCTIONS

  • Choi, Chang-Sun
    • Journal of the Korean Mathematical Society
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    • v.34 no.3
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    • pp.543-551
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    • 1997
  • We prove a norm inequality of the form $\left\$\mid$ \upsilon \right\$\mid$ \leq (r - 1) \left\$\mid$ u \right\$\mid$_p, 1 < p < \infty$, between a non-negative subharmonic function u and a smooth function $\upsilon$ satisfying $$\mid$\upsilon(0)$\mid$ \leq u(0), $\mid$\nabla\upsilon$\mid$ \leq \nabla u$\mid$$ and $\mid$\Delta\upsilon$\mid$ \leq \alpha\Delta u$, where $\alpha$ is a constant with $0 \leq \alpha \leq 1$. This inequality extends Burkholder's inequality where $\alpha = 1$.

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UNIFORM AND COUNIFORM DIMENSION OF GENERALIZED INVERSE POLYNOMIAL MODULES

  • Zhao, Renyu
    • Bulletin of the Korean Mathematical Society
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    • v.49 no.5
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    • pp.1067-1079
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    • 2012
  • Let M be a right R-module, (S, ${\leq}$) a strictly totally ordered monoid which is also artinian and ${\omega}:S{\rightarrow}Aut(R)$ a monoid homomorphism, and let $[M^{S,{\leq}}]_{[[R^{S,{\leq}},{\omega}]]$ denote the generalized inverse polynomial module over the skew generalized power series ring [[$R^{S,{\leq}},{\omega}$]]. In this paper, we prove that $[M^{S,{\leq}}]_{[[R^{S,{\leq}},{\omega}]]$ has the same uniform dimension as its coefficient module $M_R$, and that if, in addition, R is a right perfect ring and S is a chain monoid, then $[M^{S,{\leq}}]_{[[R^{S,{\leq}},{\omega}]]$ has the same couniform dimension as its coefficient module $M_R$.