• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.76-82
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• 1996

PLZT ceramics having two nominal compositions, $Pb_{1-3x/2}La_xV_{x/2}(Zr_{03}Ti_{03})O_3$ and $Pb_{1-x}La_x(Zr_{0.2}Ti_{0.5})_{1-x/4}V_{x/4}O_3$ (V: vacancy) with x=0.00~0.30, were prepared. The physical, structural, and dielectric properties were investigated by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and measurements of bulk density and dielectric constant. The two series with A-stie and B-site vacancies showed different physical, structural, dielectric properties, and, specially, Curie temperature. In comparison to PLZT with B-site vacancies, PLZT with A-site vacancies showed high Curie temperatures and low maxima of dielectric constant. Consequently, it is evident that the properties of PLZT ceramics depend on the vacancy formula adopted as a batch composition in preparation.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.11-13
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• 2006

[ $M\"{o}ssbauer$ ] spectra of $Ti_{1-x-y}Co_xFe_yO_2(0.01{\leq}x,\;y{\leq}0.05)$ prepared with $^{57}Fe$ enriched iron have been taken at various temperatures ranging from 80 to 300K. The Mossbauer spectrum of $Ti0.94Co_{0.03}Fe_{0.03}O_2$ consists of a ferromagnetic (six-Lorentzian), a paramagnetic phase (doublet) and armorphous phase over all temperature ranges. Isomer shifts indicate $Fe^{3+}$ for the ferromagnetic phase and the paramagneic phase of $Ti_{1-x-y}Co_xFe_yO_2$ samples. It is noted that the magnetic hyperfine field of ferromagnetic phase had the value about 1.5 times as large as that of u-fe. The XRB data for $Ti_{1-x-y}Co_xFe_yO_2$ showed mainly rutile phase with tetragonal structures without any segregation of Co and Fe into particulates within the instrumental resolution limit. The magnetic moment per (Co+Fe) atom in $Ti0.94Co_{0.03}Fe_{0.03}O_2$, under the applied field of 1T was estimated to be about $0.332{\mu}_B$ which is ten times as large as that of $Ti0.97Co_{0.03}Fe_{0.03}O_2,\;0.024{\mu}_B$ per Co atom, suggesting a high spin configuration of Co and fe ions.

• Journal of The Korean Astronomical Society
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• v.52 no.2
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• pp.41-47
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• 2019

We report on the timing properties of the 'Crab twin' pulsar PSR B0540-69 measured with X-ray data taken with the Swift telescope over a period of 1100 days. The braking index of the pulsar was estimated to be $n=0.03{\pm}0.013$ in a previous study performed in 2015 with 500-day Swift data. This small value of n is unusual for pulsars, and a comparison with an old estimate of $n{\approx}2.1$ for the same target determined ~10 years earlier suggests a dramatic change in the braking index. To confirm the small value and therefore the large change of n, we used 1100-day Swift observations including the data used in the earlier determination of n = 0.03. In this study we find that the braking index of PSR B0540-69 is $n=0.163{\pm}0.001$, somewhat larger than 0.03. Since the measured value of n is still much smaller than 2.1, we can confirm the dramatic change in the braking index for this pulsar.

• Nonlinear Functional Analysis and Applications
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• v.28 no.4
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• pp.887-902
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• 2023

In this article, we investigate an approximate quadratic Lie *-derivation of a quadratic functional equation f(ax + by) + abf(x - y) = (a + b)(af(x) + bf(y)), where ab ≠ 0, a, b ∈ ℕ, associated with the identity f([x, y]) = [f(x), y²] + [x², f(y)] on a 𝜌-complete convex modular *-algebra χ_𝜌 by using ∆₂-condition via convex modular 𝜌.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.355-362
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• 2015

In this study, we have fabricated 9.385[GHz] circulator that is composed of WR112 waveguide and Ferrite for X-band radar. For designing Ferrite, B/R mode(Below Resonance mode) was used and calculated the condition of 120 degree rotation of the electric field in Ferrite and calculated internal DC magnetic field and external DC magnetic field. Also, dielectric materials of the same shape with Ferrite was filled between two Ferrite for improving the performance of the circulator, including impedance matching, bandwidth, quality factor, insertion loss. To obtain optimum shape of the Ferrite and dielectric material, we used CST MWS. Simulation result of the circulator is that 1.02 : 1 VSWR, -40dB isolation, 0.2dB insertion loss and measurement result is that 1.03 : 1, -38dB, 1.2dB at 9.385[GHz]. We can get good agreement at isolation and VSWR, but insertion loss was 1 dB great than simulation result.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.603-607
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• 2010

Turquoise blue pigment of Vanadium-zircon blue (DCMA number 14-42-2), which was already commercialized, was stable to be reproduced but insufficient to give strong blue. However, it possible to obtain more intense blue by partially substituting cobalt ions into the willemite($Zn_2SiO_4$) lattice classified into DCMA number 7-10-2 for blue ceramic pigment. By the composition of willemite $Co_xZn_{2-x}SiO_4$(X=0.01, 0.03, 0.05, 0.07, 0.09 mole), this study used reagent grade zinc oxide, cobalt oxide and silicon dioxide as starting materials, carrying out the synthesis with solid reaction method by adding $H_3BO_3$ as a mineralizer. The firing temperature was between $1200^{\circ}C$ and $1400^{\circ}C$. The characteristics of synthesized pigment were analyzed by X-ray diffraction, Raman spectroscopy and SEM and the characteristics of color tones were analyzed by UV-Vis spectroscopy and CIE-$L^*a^*b^*$ measurement. As a result, the optimal composition was $Zn_{1.95}Co_{0.05}$ with 1wt% of $H_3BO_3$ as a mineralizer and firing condition was $1350^{\circ}C$/3 h. $L^*a^*b^*$ value was 29.25, 41.03, -59.93 for on glaze pigment and 37.03, 36.41, -60.03 for under glaze pigment.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.94-96
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• 2002

The $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%) were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD and SEM. According to the X-ray diffraction patterns of the $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%), the ilmenite $MgTiO_3$ and perovskite $SrTiO_3$ structures were coexisted and secondary phase $MgTi_2O_5$ were appeared. Increasing the sintering temperature. the grain size was increased. In the case of $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency were $13.52{\sim}18.13,\;32750{\sim}51736GHz$, $-15.78{\sim}25.64ppm/^{\circ}C$, respectively.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.56-62
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• 1992

The GaAs bulk crystals are grown by the Synthesis Solute Diffusion(SSD) method and its properties are investigated. The crystal growth rate at optimum condition is 0.28 cm/day and their temperature dependence is R(T) = 2.92 x 10S04T exp(-1.548eV/kS1BTT) [cmS02T/day.K]. Etch pits density distribution along radial direction is order of 10S04TcmS0-2T and 10S03TcmS0-2T at the edge and middle of the wafers, respectively, and it increased exponentially along vertical direction of ingot. Moreover,it is uniformly distributed as order of 10S03TcmS0-2T in radial direction of In doped GaAs. The carrier concentration and mobilities are measured to 0.34-2.1 x 10S016T cmS0-3T and 2.3-3.3x10S03T cmS02T/V.sec, respectively.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.405-409
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• 2003

The effect of substitution of Gd ions for Ca ions in the B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$(C $a_{1-x}$ G $d_{x}$)$_{2.03}$ C $u_{3.06}$ $O_{ 10+{\delta}}$/ (x=0.0~0.06) was investigated by measuring x-ray diffraction patterns, lattice constants, do resistivity and Hall effect. We found the solubility limit of Gd in the 110 K phase to be x < 0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature $T_{c}$ gradually decreased with an increasing the Gd concentration x, corresponding to a small change of the carrier concentration.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.29-33
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• 1973

This experimental work was carried out to examine the relation between the filament characteristic and the tensile property of various cocoon varieties. Cocoons of 21 varieties were used as materials, from which, bave denier (X$_1$), sericin solubility (X$_2$), tenacity (Y$_1$), elongation (Y$_2$), and Young's modulus (Y$_3$) were tested. The formulae estimating tensile properties with denier and sericin solubility are as follows: A) In case of denier. Y$_1$= -0.4X$_1$＋5.03 Y$_2$=1.2X$_1$＋2.7 Y$_3$= -25.2X$_1$＋140.95 B) In case of sericin solubility Y$_1$= -2.4X$_2$＋3.43 Y$_2$=20X$_2$＋3.7 Y$_3$= -120X$_2$＋78.37.