• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.104-107
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• 2001

The fabricated La-modified lead titanate (PLT) thin flim without paling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method. $Pb_{1-x}La_{x}Ti_{1-x/4}O_{3}$ PLT (x=0.1) thin film having 10 mol% La content was deposited on a $Pt/TiO_{x}/SiO_{2}/Si$ substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is $6.6{\times}10^{-9}C/cm_{2}\cdot K$ without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are $1.03{\times}10^{-11}C\cdot cm/J$ and $1.46\times 10^{-9}C\cdot cm/J$, respectively. The PLT(10) thin film has voltage responsivity (Rv) of 5.15 V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity (D*) of the PLT(10) thin film are$9.93{\times}10^{-8}W/Hz^{1/2}$ and $1.81\times 10^{6}cmHz^{1/2}/W$ at the same frequency of 100 Hz, respectively. The results means that PLT thin film having 10 mol % La content is suitable for the sensing materials of pyroelectric IR sensors.

• Journal of the Chungcheong Mathematical Society
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• v.32 no.3
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• pp.337-347
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• 2019

In this paper, we investigate the generalized Hyers-Ulam stability of the quadratic and quartic type functional equations $$f(kx+y)+f(kx-y)-k^2f(x+y)-k^2f(x-y)-2f(kx)\\{\hfill{67}}+2k^2f(x)+2(k^2-1)f(y)=0,\\f(x+5y)-5f(x+4y)+10f(x+3y)-10f(x+2y)+5f(x+y)\\{\hfill{67}}-f(-x)=0,\\f(kx+y)+f(kx-y)-k^2f(x+y)-k^2f(x-y)\\{\hfill{67}}-{\frac{k^2(k^2-1)}{6}}[f(2x)-4f(x)]+2(k^2-1)f(y)=0$$ by using the fixed point theory in the sense of L. $C{\breve{a}}dariu$ and V. Radu.

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.323-332
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• 1976

The x or $x^0+x'$ values of the nonstoichiometric chemical formula $TiO_{2-x}$ or $Ti_{2-(x^0+x')}$ have been measured by a specially made magnetic quartz microbalance in a temperature range from 600 to $1300^{\circ}C$ under oxygen pressures of $1{\times}10^{-6} to 1 atm. The standard x or $x^0$ value of the rutile is 0.00148. The x values $under_xoxygen$ pressure of 1 atm decrease with temperatures and then the stoichiometric rutile (or x = 0) is formed at $1130^{\circ}C$. The x values varied between 0.00148 and 0.01719 at a temperature range from 600 to $1300^{\circ}C$ under $1{\times}10^{-9}{\sim}1{\times}10^{-2}$ atm oxygen pressures. The enthalpies of formation of the nonstoichiometric rutile, $H_f$, varied between 21.05 and 29.97 Kcal/mole under the above conditions. The 1/n values calculated from the plots of log X' vs. log $Po_2$ are -{\frac{1}{2}}{\sim}-{\frac{1}{4}} under low oxygen pressure range of $1{\times}10^{-6}\;to\;1{\times}10^{-4}$ atm. Many physical properties of the titanium dioxide, such as the stability of the rutile, Electrical conductivity, catalytic activity and defects, can be explained through the x values and the thermodynamic data calculated from the temperature and oxygen pressure dependences of the x' values.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.428-438
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• 1995

The gelatinization properties of corn and waxy corn starch doughs were examined at various moisture contents, heating temperatures and heating times. The onset temperatures of gelatinization with 1% CMC using Brabender Amylograph were $64^{\circ}C$ for both corn and waxy corn starch. In the gelatinization properties using DSC, onset temperature$(T_o)$, maximum peak temperature$(T_p)$, completion temperature$(T_c)$ and enthalpy of the corn starch were $68.15^{\circ}C,\;74.01^{\circ}C,\;85.65^{\circ}C$ and $3.2\;cal/gram$ respectively. While those of the waxy corn starch were $68.24^{\circ}C,\;75.43^{\circ}C,\;93^{\circ}C$ and $4.2\;cal/gram$ respectively. In enzymatic analysis, when the moisture content increased from 36% to 52% and heating temperature from $60^{\circ}C$ to $100^{\circ}C$, the gelatinization degree of starch dough increased from about 10% to about 62%. The gelatinization degree of waxy corn starch dough was $15{\sim}20%$ higher than that of corn starch dough under the same gelatinization conditions. The regression equations of gelatinization degree (Y) of starch dough in the range of $36{\sim}52%$ moisture content $(X_1)\;60{\sim}100^{\circ}C$ heating temperature $(X_2)\;and\;0{\sim}2.0$ min heating time $(X_3)$ were examined using response surface analysis. The regression equation of corn starch dough was: $Y=28.659+8.638\;X_}+15.675\;X_2+7.770\;X_3-1.620\;{X_1}^2+10.790\;X_1X_2-4.220\;{X_2}^2+0.510\;X_1X_3+1.980\;X_2X_3-6.850\;{X_3}^2\;(R^2=0.9714)$ and that of waxy corn starch dough was: $Y=32.617+12.535\;X_1+20.470\;X_2+8.608\;X_3+4.093\;{X_1}^2+13.550\;X_1X_2-4.467\;{X_2}^2+1.560\;X_1X_3+2.160\;X_2X_3-9.527\;{X_3}^2$\;(R^2=0.9621)$. As the moisture content, heating temperature and heating time increased, the reaction rate constant(k) of gelatinization increased. The greatest reaction rate constant was observed at initial 0.5 min heating time of 1st gelatinization stage. At the heating temperature of $90^{\circ}C$, gelatinization of starch dough was completed almost in the initial 0.5 min heating time. The reaction rate constant of waxy corn starch dough was higher than that of corn starch dough under the same gelatinization conditions. At the 52% moisture content, the regression equation between reaction rate constant(k) and heating temperature(T) for corn starch dough was $log\;k=11.1140-4.1226{\times}10^3(1/T)$ (r=-0.9520) and that of waxy corn starch dough was $log\;k=10.1195-3.7090{\times}10^3(1/T)$ (r=-0.9064).

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.775-779
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• 1998

The resonant frequency fo and unloaded quality factor Qu of CoTi-substituted Barium ferrites($\textrm{BaCo}_{x}\textrm{Ti}_{x}\textrm{Fe}_{12-2x}\textrm{O}_{19}$, $1.0\leq\textrm{x}\leq5.0$) were measured at frequencies between 5 to 10GHz using the paralleled copper-plate wave guide method. The measurements showed that the permittivities of CoTi-substituted Barium ferrites(CoTi-BF) increased from 14.7 to 23.4 with the contents of CoTi, x, and the loss tangents had values of $\textrm{10}^{-3}$ order. From these results, CoTi-BF are considered to be very promising materials in microwave devices such as dielctric resonator antennas.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.1
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• pp.221-229
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• 2013

We show that if X is a space such that ${\beta}QF(X)=QF({\beta}X)$ and each stable $Z(X)^{\sharp}$-ultrafilter has the countable intersection property, then there is a homeomorphism $h_X:vQF(X){\rightarrow}QF(vX)$ with $r_X={\Phi}_{vX}{\circ}h_X$. Moreover, if ${\beta}QF(X)=QF({\beta}X)$ and $vE(X)=E(vX)$ or $v{\Lambda}(X)={\Lambda}(vX)$, then $vQF(X)=QF(vX)$.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.77-87
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• 2020

In this paper, we investigate the stability of a functional equation f(x + 3y) - 5f(x + 2y) + 10f(x + y) - 8f(x) + 5f(x - y) - f(x - 2y) - 2f(-x) - f(2x) + f(-2x) = 0 by using the fixed point theory in the sense of L. Cǎdariu and V. Radu.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.101-109
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• 2011

The Riemann's zeta function $\zeta(s)$ has been known as answer for a number of primes $\pi$(x) less than given number x. In prime number theorem, there are another approximation function $\frac{x}{lnx}$,Li(x), and R(x). The error about $\pi$(x) is R(x) < Li(x) < $\frac{x}{lnx}$. The logarithmic integral function is Li(x) = $\int_{2}^{x}\frac{1}{lnt}dt$ ~ $\frac{x}{lnx}\sum\limits_{k=0}^{\infty}\frac{k!}{(lnx)^k}=\frac{x}{lnx}(1+\frac{1!}{(lnx)^1}+\frac{2!}{(lnx)^2}+\cdots)$. This paper shows that the $\pi$(x) can be represent with finite Li(x), and presents generalized prime counting function $\sqrt{{\alpha}x}{\pm}{\beta}$. Firstly, the $\pi$(x) can be represent to $Li_3(x)=\frac{x}{lnx}(\sum\limits_{t=0}^{{\alpha}}\frac{k!}{(lnx)^k}{\pm}{\beta})$ and $Li_4(x)=\lfloor\frac{x}{lnx}(1+{\alpha}\frac{k!}{(lnx)^k}{\pm}{\beta})}k\geq2$ such that $0{\leq}t{\leq}2k$. Then, $Li_3$(x) is adjusted by $\pi(x){\simeq}Li_3(x)$ with ${\alpha}$ and error compensation value ${\beta}$. As a results, this paper get the $Li_3(x)=Li_4(x)=\pi(x)$ for $x=10^k$. Then, this paper suggests a generalized function $\pi(x)=\sqrt{{\alpha}x}{\pm}{\beta}$. The $\pi(x)=\sqrt{{\alpha}x}{\pm}{\beta}$ function superior than Riemann's zeta function in representation of prime counting.

• Journal of the Korean Mathematical Society
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• v.45 no.4
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• pp.1089-1100
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• 2008

For a pointed space X, the subgroups of self-homotopy equivalences $Aut_{\sharp}_N(X)$, $Aut_{\Omega}(X)$, $Aut_*(X)$ and $Aut_{\Sigma}(X)$ are considered, where $Aut_{\sharp}_N(X)$ is the group of all self-homotopy classes f of X such that $f_{\sharp}=id\;:\;{\pi_i}(X){\rightarrow}{\pi_i}(X)$ for all $i{\leq}N{\leq}{\infty}$, $Aut_{\Omega}(X)$ is the group of all the above f such that ${\Omega}f=id;\;Aut_*(X)$ is the group of all self-homotopy classes g of X such that $g_*=id\;:\;H_i(X){\rightarrow}H_i(X)$ for all $i{\leq}{\infty}$, $Aut_{\Sigma}(X)$ is the group of all the above g such that ${\Sigma}g=id$. We will prove that $Aut_{\Omega}(X_1{\times}\cdots{\times}X_n)$ has two factorizations similar to those of $Aut_{\sharp}_N(X_1{\times}\cdots{\times}\;X_n)$ in reference [10], and that $Aut_{\Sigma}(X_1{\vee}\cdots{\vee}X_n)$, $Aut_*(X_1{\vee}\cdots{\vee}X_n)$ also have factorizations being dual to the former two cases respectively.

• Elastomers and Composites
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• v.28 no.2
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• pp.103-107
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• 1993

To make new filler for conducting rubber, the sample of perovskite-related ferrite system $Dy_{2-x}Sr_{1+x}Fe_2O_{7-y}$ (x=0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized at 1473K in air. $M{\ddot{o}}ssbauer$ spetrum of x=0.0 sample shows typical six line pattern with $M{\ddot{o}}ssbauer$ parameters, $I.S=3.6{\times}10^{-1}mm/sec,\;E_Q=-7.0{\times}10^{-2}mm/sec,\;H_{int}=5.19{\times}10^2\;Koe$. In case of x=2.0, the spectrum is composed of single line exhibiting coexistance of $Fe^{3+}(I.S.=3.7{\times}10^{-1}mm/sec)$ ions and $Fe^{4+}(I.S.=-1.9{\times}10^{-1}mm/sec)$ ions. With increase in x value electrical conductivity at constant temperature sharply increased and the activation energies decreased from $3.8{\times}10^{-1}\;to\;1.9{\times}10^{-1}\;eV$.