• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.647-653
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• 2011

In this study, a method to measure the thickness of thin film by EDS (energy dispersive spectroscopy) is suggested. We have developed a model which calculates the thickness of thin film from the characteristic x-ray intensity ratio of the elements in thin film and substrate by considering incident electron beam energy, x-ray generation curve, backscattering and absorption of x-ray, take-off angle of x-ray and tilt angle of the sample. We obtained the relation curve between the film thickness measured experimentally and the x-ray intensity ratio of elements. The film thicknesses calculated from the model agrees quite well with those measured experimentally. Therefore, the thin film thickness can be measured rapidly and accurately by using the model developed in this study and the x-ray intensity ratio obtained in EDS analysis.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.48-52
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• 2003

The substituted yttrium iron garnet systems $Y_{ 3-x}$/Gd$_{x}$X$0.2_{0.2}$ $Fe_{4.8}$ $O _{12}$ (x = 0.2, 0.4, 0.6) have been investigated by means of X-ray diffraction, Mossbauer spectroscopy and SQUID. The X-ray diffraction patterns at room temperature confirm the samples to have a single phase of the garnet structure over the whole composition range. The lattice constants of all the samples linearly change with increasing x due to the size of substituted ions in the dodecahedral sites. $Y_{3-x}$ $Gd_{x}$ X$Fe_{4.8}$ $In_{0.2}$ $O_{12}$ system which $Y_{3-x}$ ions are substituted with Gd$^{ 3＋}$ ions, the Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the $Fe^{3＋}$ ions on the octahedral(a-) sites and the others due to the $Fe^{3＋}$ ions on the tetrahedral(d-, d'-) sites, respectively. From the hysteresis loop measured by means of SQUID over the whole composition range, the saturation magnetization $M_{s}$ and magnetic moments $\mu_{ B}$ per unit cell have been obtained. The increment of Gd-ion content causes $M_{s}$ and $\mu_{B}$ decrease while the increment of In-ion content does not.

• Journal of the Chungcheong Mathematical Society
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• v.19 no.3
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• pp.275-281
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• 2006

In this article, we establish the stability of the orthogonally cubic type functional equation 2f(x + 2y) + 2f(x - 2y) + 2f(2x)+7[f(x)+f(-x)] = 4f(x)+8[f(x+y)+f(x-y)], $x{\bot}y$ in which ${\bot}$ is the orthogonality in the sense in the R$\ddot{a}$tz.

• 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.

• Proceedings of the KWS Conference
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• 1993.05a
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• pp.82-84
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• 1993

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.478-484
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• 2000

The structural changes and the microwave dielectric properties of $Ba_{1-x}$/A$_{x}$/(Mg$_{1}$3//Nb$_{2}$3/)O$_3$(A=Sr, Ca=x0, 0.2, 0.4, 0.6, 0.8, 1.0) were investigated. The densities of samples are gradually decreased with increasing x(BMN=6.1, SMN=5.22 and CMN=4.26 g/m$^3$)The crystal structure of BMN was untilting of oxygen octahedral. The structural changes of BSMN showed the antiphase tilting at x>0.4, and those of BCMN showed the antiphase tilting at 0.20.8. The variation of dielectric constant with Sr was small(BMN=32, SMN=30) However the variation with Ca was large the highest value was 42 at Ca=0.2(CMN=25) The maximum quality factor was 68,000 GHz at Sr=0.2 and the minimum quality factor was 3,000 GHz at Ca=0.2 (BMN=35,000, SMN=20,000 and CMN=23,000 GHz) The temperature coefficients of resonant frequency of BSMN were about 2 times larger than those of BCMN in all composition.ion.

• Current Photovoltaic Research
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• v.3 no.1
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• pp.16-20
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• 2015

Ag addition in chalcopyrite materials is known to lead beneficial changes in aspects of structural and electronic properties. In this work, the effects of Ag alloying of $Cu(In,Ga)Se_2$-based solar cells has been investigated. Wide bandgap $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x = 0.75~0.8) films have been deposited using a three-stage co-evaporation with various Ag/(Ag+Cu) ratios. With Ag alloying the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films were found to have greater grainsize and film thickness. Device were also fabricated with the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films and their J-V and quantum efficiency measurements were carried out. The highest-efficiency $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ solar cell with Eg > 1.5 eV had an efficiency of 12.2% with device parameters $V_{OC}=0.810V$, $J_{SC}=21.7mA/cm^2$, and FF = 69.0%.

• Journal of Life Science
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• v.13 no.1
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• pp.118-127
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• 2003

$\rho$-Fluorophenylalanine (FPA), a phenylalanine analog, is able to induce apoptotic cell death of human acute leukemia Jurkat T cells. To better understand the mechanism by which FPA induces apoptotic cell death, the effect of ectopic expression of antiapoptotic proteins, Bcl-2 and Bcl-xL, on FPA-induced apoptosis was investigated by employing lurkat T cells transfected with Bcl-2 gene (JT/Bcl-2) or Bcl-xL gene (1/Bcl-xL) and Jurkat T cells transfected with vector (JT/Neo or J/Neo). When Jurkat T cells, JT/Neo or J/Neo, were exposed to FPA at concentrations ranging from 0.63 to 5.0 mM, the cell viability determined by MTT assay declined in a dose-dependent manner. In addition, apoptotic DNA fragmentation along with several apoptotic events such as caspase-8 activation, Bid cleavage, mitochondrial cytochrome c release, caspase-9 activation, caspase-3 activation, and degradation of PARP was induced. However, the FPA-induced cytotoxic effect, activation of caspase-8, and cleavage of Bid were significantly abrogated by ectopic expression of Bcl-2 or Bcl-xL. At the same time, there was marked reduction in the level of cytochrome c release from mitorhondria, caspase-9 activation, caspase-3 activation, and degradation of PARP. These results indicate that caspase-8 activation, Bid cleavage, and mitochondrial cytochrome c release with subsequent activation of the caspase cascade are negatively regulated by Bcl-2 or Bcl-xL, and are thus required for FPA-induced apoptosis in Jurkat T cells

• 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 Korean Chemical Society
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• v.27 no.3
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• pp.189-193
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• 1983

The lithium isotopes separation experiments were carried out in hydrochloric acid with cation exchanger systerns. In these experiments were employed porous sulfonated styrene-divinylbenzene copolymer and Dowex 50w-x8 as cation exchanger. The contents of lithium of the fraction were determined with atomic absorption spectrophotometer. The relative mass of lithium isotopes of the fractions was analyzed on a mass spectrometer. The isotope separation factors of lithium were calculated from the isotope compositions of these eluted fractions. Separation factor for the system in hydrochloric acid and porous sulfonated styrene-divinylbenzene copolymer was found to be 1.0020, and for the case of system in hydrochloric acid and Dowex 50w-x8 was 1.0011${\om}$0.0002. From these results, we found that the separation factor for porous sulfonated styrene-divinylbenzene copolymer ionexchanger is larger than value of Dowex 50w-x8 ionexchanger.