• Journal of the Chungcheong Mathematical Society
• /
• v.20 no.1
• /
• pp.37-45
• /
• 2007

Let X, Y be vector spaces. In this paper, we investigate the generalized Hyers-Ulam-Rassias stability problem for a cubic function $f:X{\rightarrow}Y$ satisfies $$r^3f(\frac{\Sigma_{j=1}^{n-1}x_j+2x_n}{r})+r^3f(\frac{\Sigma_{j=1}^{n-1}x_j-2x_n}{r})+8\sum_{j=1}^{n-1}f(x_j)=2f{\sum_{j=1}^{n-1}}x_j)+4{\sum_{j=1}^{n-1}}(f(x_j+x_n)+f(x_j-x_n))$$ for all $x_1,{\cdots},x_n{\in}X$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.3
• /
• pp.231-237
• /
• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.8
• /
• pp.840-845
• /
• 2004

The microstructure and microwave dielectric properties of $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics were investigated. The specimens were prepared by the conventional mixed oxide method with sintering temperature of 140$0^{\circ}C$∼150$0^{\circ}C$. To improve the quality factor and the temperature coefficient of resonant frequency,$ Ti{O}_2(\varepsilon\Gamma=100, Q\times f_\Gamma=40,000 GHz,\ta_f= +450 ppm\diagup^{\circ}C $ was added in ${Mg}_4{Ta}_2{O}_9$ceramics. The dielectric and structural properties were investigated. According to the XRD patterns, $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics had the ${Mg}_4{Ta}_2{O}_9$ phase(hexagonal) and ${MgTi}_2{O}_5$phase(orthorhombic). The dielectric constant($\varepsilon_r$). quality($Qtimes{f}_r$${\tau}_f$) of the $(1-x){Mg}_4{Ta}_2{O}_9-xTi{O}_2(x=0\sim0.9)$ ceramics were 8.12∼18.59, 18,750∼186,410 GHz and －36.02∼＋3.46 ppm/$^{\circ}C$, respectively.

• Communications of the Korean Mathematical Society
• /
• v.31 no.4
• /
• pp.857-868
• /
• 2016

Let (X, ${\mu}$) be a generalized topological space (GTS) and $\mathcal{H}$ be a hereditary class on X due to $Cs{\acute{a}}sz{\acute{a}}r$ [8]. In this paper, we define an operator $()^{\circ}:\mathcal{P}(X){\rightarrow}\mathcal{P}(X)$. By setting $c^{\circ}(A)=A{\cup}A^{\circ}$ for every subset A of X, we define the family ${\mu}^{\circ}=\{M{\subseteq}X:X-M=c^{\circ}(X-M)\}$ and show that ${\mu}^{\circ}$ is a GT on X such that ${\mu}({\theta}){\subseteq}{\mu}^{\circ}{\subseteq}{\mu}^*$, where ${\mu}^*$ is a GT in [8]. Moreover, we define and investigate ${\mu}^{\circ}$-codense and strongly ${\mu}^{\circ}$-codense hereditary classes.

• 한국초전도학회:학술대회논문집
• /
• v.12
• /
• pp.8-8
• /
• 2002

• 한국전기화학회:학술대회논문집
• /
• 1999.04a
• /
• pp.8-8
• /
• 1999

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.229-231
• /
• 1996

We are studied the stability of amorphous and crystalline $Te_{100-x}Ge_x$ (x=10, 15. 25, 40, 50, 60 at.%) thin films by observing the degradation in 8O%RH/$66^{\circ}C$ environment and the reflectance ratio. The degradation was observed with the transmittance and reflectance, the reflectance was measured at 780nm in the wavelength range of diode laser. In amorphous $Te_{100-x}Ge_x$ thin films of below x=4O at.%, the degradation was observed, the thin film of x=10 at.% was shown the degradation degree of 12.5%. In crystalline $Te_{100-x}Ge_x$ thin films of x=10, 40 at.%, the degradation degree were 12.8%, 13%, respectively. The reflectance ratio were shown above 20% in. all composition ratio. Therefore, we are expected that $Te_{100-x}Ge_x$ thin films of x=50, 60 at.% has the long life for the optical recording media.

• Korean Journal of Materials Research
• /
• v.28 no.8
• /
• pp.474-477
• /
• 2018

$Ca_3MgSi_2O_8:Eu^{2+}$(x = 0.003, 0.005, 0.007, 0.01, 0.03 mol) white phosphors for Light Emitting Diodes(LED) are synthesized with different concentrations of $Eu^{2+}$ ions using a solid state reaction method. The crystal structures, surface and optical properties of the phosphors are investigated using X-Ray Diffraction(XRD), Scanning Electron Microscope(SEM) and photoluminescence(PL). The X-Ray Diffraction results reveals that the crystal structure of the $Ca_3MgSi_2O_8:Eu^{2+}$ is a monoclinic system. The particle size of $Ca_3MgSi_2O_8:Eu^{2+}$ white phosphors is about $1{\sim}5{\mu}m$, as confirmed by SEM images. The maximum emission spectra of the phosphors are observed at 0.01 mol $Eu^{2+}$ concentration. The decrease in PL intensity in the $Ca_3MgSi_2O_8:Eu^{2+}$ white phosphors with $Eu^{2+}$ concentration is interpreted by concentration quenching. The International Commission on Illumination(CIE) coordinate of 0.01 mol Eu doped $Ca_3MgSi_2O_8$ is X = 0.2136, Y = 0.3771.

• Korean Journal of Medicinal Crop Science
• /
• v.12 no.6
• /
• pp.490-493
• /
• 2004

Karyotypes were established in five Pulsatilla species from Korea : P. cernua, P. davurica, P. koreana, P. chinensis and P. tongkangensis. The somatic chromosome numbers of five species were all 2n=2x=16 with the basic number of x=8. The chromosome complement of P. cernua consisted of 5 pairs of metacentric, 1 pair of submetacentric and 2 pairs of subtelocentric. P. davurica, P. koreana and P. chinensis consisted of 5 pairs of metacentric and 3 pairs of subtelocentric. P. tongkangensis consisted of 5 pairs of metacentric, 2 pairs of submetacentric, and 1 pair of subtelocentric. Karyotype formulas of P. davurica, P. koreana, and P. chinensis were the same as K (2n) = 2x = 16 = 10m + 6st, while those of P. cernua was K (2n) = 2x = 16 = 10m + 2sm + 4st and P. tongkangensis was K (2n) = 2x = 16 = 10m + 4sm + 2st, respectively.

• Korean Journal of Animal Reproduction
• /
• v.15 no.3
• /
• pp.189-193
• /
• 1991

This study was carried out ot investigate effects of X-537A on hydrogen ion concentration insperm washed solution and sperm acrosome reaction. The results obtained were as follows. 1. When bovine sperm was twice washed with SHP solutions of pH 6.8 and 7.4 and again washed with SHP solution containing 4$\mu$M of X-537A, in case of pH 6.8 the sperm washed with 4$\mu$M of X-537A showed signifciantly(p<0.01) higher hydrogen ion concentration in sperm washed solution than the sperm washed without X-537A. 2. When the sperm was twice washed with SHP solution and then washed with SHP solution containing 4$\mu$M of X-537A, sperm acrosome rection rate was signifciantly(p<0.01) increased from 12min after incubation in the sperm washed without X-537A, but was signifciantly(p<0.01) increased from 8 min after incubation in the sperm washed with 4$\mu$M of X-537A. 3. When the sperm was twice washed with SHP solution and then washed with SHP solution containing 0, 4 and 40$\mu$M of X-537A, and then incubated in m-TALP for 120 min, sperm acrosome reaction rate was significantly(p<0.01) increased from 15 min after incubation in 0, 4 and 40$\mu$m OF X-537A. However at 60 min incubation 40$\mu$M of X-537A showed significantly(p<0.01) higher sperm acrosome reaction rate than 0 and 4$\mu$M and at 120 min incubation 4 and 40$\mu$M of X-537A showed signifciantly(p<0.01) higher acrosome reaction rate than 0$\mu$M of X-537A.