• Bulletin of the Korean Chemical Society
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• v.18 no.3
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• pp.305-310
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• 1997

The synthesis and characterization of the platinum heterocyclic carboxaldehyde thiosemicarbazone complexes [NC5H4CRNNC(S)NHR'PtCl] (R=H, R'=CH3(1); R=CH3, R'=CH3(2); R=CH3, R=H(3)) and diphenylphosphinophenyl carboxaldehyde thiosemicarbazone complexes [Ph2PC6H4CHNNC(S)NHRPtCl] (R=CH3(5); R=iC3H7(6); R=Ph(7)) are described. Compounds 1-3 were prepared by reaction of Pt(SEt2)2Cl2 with 2-acetylpyridine-4-alkylthiosemicarbazone in the presence of NEt3. Compounds 5-7 were prepared using Pt(SEt2)2Cl2 in toluene with diphenylphosphinophenyl carboxaldehyde alkylthiosemicarbazone. The compounds have been characterized by microanalysis, NMR (1H, 13C, 31P) spectroscopy, and single-crystal X-ray diffraction. X-ray single crystal diffraction analysis reveals that compound 5 is a mononuclear platinum compound with P,N,S-coordination mode.

• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.513-518
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• 2003

La/sub 2/3-x/Li/sub 3x/□/sub 1/3-2x/TiO₃ compounds with x=0.13 and 0.12 were prepared by slow cooling (x=0.13) and rapid quenching (x=0.12) into the liquid nitrogen after sintering at 1350℃ for 6 h. Their crystal structure has been determined by Rietveld refinement of both the powder neutron and X-ray diffraction data. From neutron diffraction data, we found that the main phase was not tetragonal (P4/mmm), but trigonal (R3cH). The refinement of neutron diffraction for the slow cooled samples were in a good agreement with a new model; a mixture of trigonal (R3cH, 45.7 wt％), tetragonal (p4/mmm, 37.0 wt％), and Li/sub 0.57/Ti/sub 0.86/O₂(pbnm, 17.2 wt%), but the quenched sample was found not to contain tetragonal (p4/mmm). X-ray diffraction data couldn't be well fitted because of the Poor scattering factor of lithium ions and the similar reflection patterns among trigonal (R3cH), tetragonal (p4/mmm), and cubic (Pm3m). We also knew that one transport bottlenecks is destroyed by one La vacancy in the case of trigonal (R3cH).

• Journal of the Korean Data and Information Science Society
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• v.7 no.2
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• pp.289-294
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• 1996

This paper considers the limit of the ratio of two incomplete beta functions $I_{x}(p+s,q+r)\;to\;I_{x}(p,q)\;as\;p+q{\rightarrow}{\infty}$. The results show that the limits depend on r,s,x and the limit of p/(p+q).

• Journal of the Korean Ceramic Society
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• v.34 no.4
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• pp.368-372
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• 1997

The microwave dielectric properties of (1-x)La2/3TiO3-xLaAlO3 system in which LaAlO3 having $\varepsilon$r$\geq$90 and positive $\tau$f was investigated. The crystal system of (1-x)La2/3TiO3-xLaAlO3 was pseudo-cubic in the range of 0.1$\leq$x$\leq$0.07. Its lattice constant increased with increasing x in spite that the amount of LaAlO3 containing of smaller Al(0.57 $\AA$) ion than Ti(0.64 $\AA$) increased. As the amount of LaAlO3 increased from x=0.1 to 0.9, the relative dielectric constant ($\varepsilon$r) decreased from 50 to 23 and the temperature coefficient of resonant frequency($\tau$f) decreased from +84 to -50. On the other hand, the value of Q.f0 reached a maximum (148,000 at 7 GHz) at x=0.7, where a rapid increase in the peak intensity of XRD occured, and further increased after prolonged sintering. The microwave dielectric properties of $\varepsilon$r=37, Q.f0=47,000 (at 7 GHz), and $\tau$f=-2 ppm/$^{\circ}C$ were obtained near 0.6La2/3TiO3-0.4LaAlO3 (x=0.4) composition.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.6-12
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• 1995

High Tc superconducting YBa$_{2}$Cu$_{3}$$O_{7-x}$ thin films were prepared on various substrates by off-axis rf magnetron sputtering method to examine the substrate effects on the film structure and its R-T characteristics. The SEM analysis showed that the surface morphology of the grown YBa$_{2}$Cu$_{3}$O.sub 7-x/, film has different characteristic structure with different substrate used. The film on (100) SrTiO$_{3}$ substrate has critical current density of 3*10$^{5}$ A/cm$^{2}$ at 77K under zero magnetic field. The X-ray diffraction measurements revealed that the films on (100) SrTiO$_{3}$ substrate have mixed a-axis and c-axis normal to the substrate surface and the films on (100) MgO and ZrO$_{2}$/sapphire substrates have c-axis normal orientation to the substrate surface. However, YBa$_{2}$Cu$_{3}$$O_{7-x}$ films on (100) sapphire substrates showed no preferential orientation.ion.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.659-663
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• 1998

The effect of Bi-substitution in $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ ceramic was studied on the formation of crystal phases, microstructure, and microwave dielectric properties. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$, solid solution (0$\leq$x$\leq$0.2) were formed by Bi-substitution into the Nd site of $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ ceramics. Average grain size increased with Bi-substitution. Dielectric constant(${\varepsilon}_r$) increased from 84 to U8, and the temperature coefficient of resonant frequency(${\tau}_f$) decreased from 44 ppm/$^{\circ}C$ to -30 ppm/$^{\circ}C$ when Bi contents increased up to x=0.2 in $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ solid solutions. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ solid solutions with x=0.04~0.08 showed the most superior microwave dielectric properties, those are ${\varepsilon}_r$= 89-92, Q . f = 5855~6091 GHz, and (${\tau}_f$)= -7.5-7.5 ppm/$^{\circ}C$.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.63-73
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• 1968

It is well known that mammalian alveolar membrane is covered with a very thin layer of surfactant film which characteristically reduces surface tension of alveolar membrane, and maintains alveolar stability. Since Clements in 1957 demonstrated that the surfactant is extractable by mincing the lung tissue in saline, various studies on the subject have been succeeded by many workers. However, the effect of radiation on the surfactant is not well clarified. Present study was attempted to observe the effect of x-irradiation on the activity of surfactant in rabbits. X-ray in dose of 300 r, 600 r or 900 r was irradiated to the chest of rabbits. The lung was removed from normal or irradiated rabbits sacrificed by arterial blood shedding, and lung-saline extract, adding 3 grams of lung tissue to 50 mili-liters of saline, was prepared by means of Vertis homogenizer. Tension-area diagram of lung extract was recorded automatically by a modified Langmuir-Wilhelmy balance with a synchronized recording system designed in this department. The surface tension of lung extract was measured at 1st, 2 nd, 3 rd, 7 th and 15 th post-radiation day in 300 r irradiated group, at 3 rd, 7 th and 15 th post-radiation day in 600 r irradiated group, 3 rd and 7 th post-radiation day in 900 r irradiated group respectively. For the histo-pathological study, lung tissue preparations were made in all irradiatiated groups on the day of experiment and in normal group. The results obtained are summarized as follows: 1. The minimal surface tension, maximal surface tension and stability index of normal rabbits lung extracts were 7.68 dynes/cm, 38.84 dynes/cm, and 1.39 respectively. 2. The activity of surfactant was depressed prominently by x-irradiation. However, increase in the dose of x-irradiation did not show any significant change in the degree of surfactant activity suppression. The most marked depression in surfactant was observed at the third post-radiation day in all irradiated groups. 3. Activity of surfactant depressed by x-irradiation showed a tendency of recovering to normal on 15 th post-radiation day. 4. The tendency of change in activity of surfactant following x-irradiation was somewhat correlative with histo-pathological changes. But the degree of depression of surfactant by x-irradiation did not correspond to the degree of histo-pathological changes, and recovery of lung tissue from radiation damage, tissue edema and congestion, seemed to be followed by restoration of surfactant activity. 5. The width of the tension-area diagram was measured at the surface area of 40% in lung extract of normal and x-irradiated rabbits. And it was found that the changes of the width corresponded well with that of minimum surface tension and of stability index in all normal and x-irradiated groups.

• Korean Journal of Mathematics
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• v.7 no.2
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• pp.151-158
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• 1999

Let (X, G) be a transformation group and ${\sigma}(X,x_0,G)$ the fundamental group of (X, G). In this paper, we prove that the Reidemeister number $R(f_G)$ for an endomorphism $f_G:(X,G){\rightarrow}(X,G)$ is a homotopy invariant. In particular, when any self-map $f:X{\rightarrow}X$ is homotopic to the identity map, we give some calculation of the lower bound of $R(f_G)$. Finally, we discuss commutativity and product formula for the Reidemeister number $R(f_G)$.

• Journal of Bio-Environment Control
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• v.14 no.4
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• pp.269-274
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• 2005

The purpose of this experiment was to investigate optimal ionic concentration of nutrient solution for water culture of young welsh onion (Allium fistulosum). For the purpose of clarification of optimal nutrient concentration to maximize growth of young welsh onion, different nutrient concentrations of Yamazaki's solution for welsh onion seedling $(NO_3^--N\;9.0,\;NH_4^+-N\;3.0,\;PO_4^{3-}-P\;6.0,\;K^+7.0,\;Ca^{2+}\;2.0,\;Mg^{2+}\;2.0,\;and\;SO_4^{2-}-S\;4.4me{\cdot}L^{-1})$ which selected by prior experiment were treated as 0.6, 1.2, 1.8, and $2.4dS{\cdot}m^{-1}$. Increments of fresh weight, dry weight and top length were the highest in 1.2 and, in the next, were placed by the order of 1.8, 2.4, and $0.6dS{\cdot}m^{-1}$ The regression coefficients for the maximal growth of fresh weight of cv. 'Geurnjanguedaepa' and 'Tokyokuro' were $y=-42.091x^2+171.79x+11.047 (R^2=0.8946,\; R=0.9458^*)\;and\;y=-50.069x2+157.58x+15.414(R^2=0.9343,\;R=0.9692^{**})$, respectively, and optimal EC levels according to regression coefficients were 1.68 and $1.57dS{\cdot}m^{-1}$. As the conclusions, optimal nutrient levels far young welsh onion were $1.2dS{\cdot}m^{-1}$ EC in the early growth stage and $1.6\~l .7dS{\cdot}m^{-1}$ in the later growth stage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.216-221
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• 2010

Employing statistical design of experiments, the difference in doping behaviors of rare-earth ions and their effects on the dielectric property and microstructure of $BaTiO_3$-MgO-$MnO_2$-($Ba_{0.4}Ca_{0.6}$) $SiO_3-Re_2O_3$ (Re = $Y_2O_3$, $Er_2O_3$) system were investigated. Through the statistical analysis we have found that the amount of $Re_2O_3$ are significantly affecting on the dielectric properties. The $Re_2O_3$ improved the dielectric constant, dielectric loss and R*C constant, so the appropriate contents of $Y_2O_3$ and $Er_2O_3$ were 0.8 ~ 1.2 mol% and 0.8 ~ 1.3 mol%, respectively. The MLCC(mutilayer chip capacitor) with $2.0{\times}1.2{\times}1.2mm$ size and 475 nF was also suited for X7R with the above composition. It showed that the dielectric constant and RC constant were 2,839 and 3,675 ${\Omega}F$, respectively in the sintering condition at $1250^{\circ}C$ in $Po_2$ $10^{-7}$ Mpa.