• Journal of the Korean Ceramic Society
• /
• v.22 no.6
• /
• pp.71-79
• /
• 1985

In order to fabricate the translucent electrooptic ceramics which are comparable to PLZT, $PNZT^*$ has been prepared from aqueous solutions of their itrate and chlorides. In the quarternary $Pb^{1-x} Nd_x(Zr_{0.63} Ti_{0.37})^{1-\frac{x}{4}O_3$, (PNZT) $(0.02\le x\ge 0.12)$ system cold-pressed PNZT slugs were sintered in $O_2$ in pt-crucible for 45 min. at 118$0^{\circ}C$ and were then heat-treated in air for 60 hrs. at 120$0^{\circ}C$ in Al2O3 crucibles containing $PbZrO_3$ powder to control the atmosphere. Mean particle size of calcined PNZT powders was 0.1~0.15${\mu}{\textrm}{m}$. It was found that the maximum value of optical transmission has been revealed at 6~8 at. % $Nd_2O_3$ added body and that their dielectric constant has been decreased as the frequency increased. Curic temperature has been varied inversely with $Nd^{3+}$ ion content up to 8 at. % and become constant above this value. $^*Pb_{1-x}Nd_x(Zr_{0.63} Ti_{0.37})_{1-2/4}O_3$

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.12 no.3
• /
• pp.2035-2042
• /
• 1970

Korean Janggi and Western plow to have developed for a long time in the east and west were tested and compared in their draft resistance. The charaderistic of Korean Janggi and plow to be able to make deep plowing, on of the most important factors influeneed the increased yield, were ofserved. The study was undertaken to obtain these basic factors' to device and construct the deep plowing Janggi. The results were as follow; 1. The draft resistance of Korean Janggi far less than that of plow and on the dry field, the influence of soil moisture contant to the draft resistance was larger in the Korean Janggi than in the western plow, but on the rice paddy, there was not differences between them. 2. The plow was more stable than that of Janggi in their operation. 3. The relation ship between the specific draft resistance and plowing depth was shown bygthe carved equation. $$K=Ax+\frac{B}{x}+C$$(K ; specific draft restance, x; plowing depth) A, B, C; Constant controled by soil and instrument factor) 4. Minimam values of the specific draft resistance were as follow; a. On the dry field; Korean Janggi; x = $8{\sim}14cm$ $4K=280{\sim}330gr/cm^2$$ Westean plow; x=$10{\sim}12cm$ $$K=480{\sim}490gr/cm^2$$ 6. On the rice paddy; Korean Janggi; x=$8{\sim}12cm$ $$K=255{\sim}280gr/cm^2$ Western plow; x=$7{\sim}10cm$ $$K=415{\sim}420grc/m^2$$

• Journal of Microbiology and Biotechnology
• /
• v.26 no.7
• /
• pp.1267-1277
• /
• 2016

Currently, enzymatic synthesis of lactulose, a synthetic prebiotic disaccharide, is commonly performed with glycosyl hydrolases. In this work, a new type of lactulose-producing biocatalyst was developed by displaying β-galactosidase from Bacillus stearothermophilus IAM11001 (Bs-β-Gal) on the surface of Bacillus subtilis 168 spores. Localization of β-Gal on the spore surface as a fusion to CotX was verified by western blot analysis, immunofluorescence microscopy, and flow cytometry. The optimum pH and temperature for the resulting spore-displayed β-Gal was 6.0 and 75℃, respectively. Under optimal conditions, it showed maximum activity of 0.42 U/mg spores (dry weight). Moreover, the spore-displayed CotX-β-Gal was employed as a whole cell biocatalyst to produce lactulose, yielding 8.8 g/l from 200 g/l lactose and 100 g/l fructose. Reusability tests showed that the spore-displayed CotX-β-Gal retained around 30.3% of its initial activity after eight successive conversion cycles. These results suggest that the CotX-mediated spore-displayed β-Gal may provide a promising strategy for lactulose production.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.8
• /
• pp.2215-2218
• /
• 2010

The series of alkali metal perhalogenates, $MXO_4$ (M=Li, Na, K and X=F, Cl, Br, I) were theoretically studied with the help of MP2 methods. Bidentate as well as tridentate structures were found to be stable minima. The bidentate structures are becoming preferred as the size of halogen increases and as the size of metal decreases. Geometrically, the M-O and M-X distances of both bidentate and tridentate structures, increase with the size of metal. Generally, the M-$O_1$ distances of tridentate forms are longer than the corresponding distances of bidentate forms, while the M-X distances of tridentate forms show the opposite trend. Similarly, the X-O bonds increase with the size of halogens except $MXO_4$ pairs, where the X-O bonds are unusually long due to the enhanced oxygen-oxygen repulsions. In short, the relative energetics as well as the geometrical parameters are found to be strongly dependent on halogen and metal elements.

• Korean Journal of Crystallography
• /
• v.11 no.1
• /
• pp.16-21
• /
• 2000

(Yb/sub x/Y/sub 1-x/)Ca₄O(BO₃)₃ single crystals where x=0.3,8,15,20% were grown by Czochralski Method. The crystals grown under the optimum conditions were transparent and colorless with good crystal form. Using polarizing microscope, crystal defects such as parasite crystals and bubbles were detected depending on the composition of melts and pulling rates. The optimum growth parameters for high quality of single crystals were 15∼20 rpm of rotation rate and 2mm/h of pulling rate at the flow rate of 2 l/min of Nitrogen gas. The relationship between crystal axes and optical axes was investigated by optical crystallographic method, polarization technique and single crystal X-ray method. From the spectroscopic measurements, it was confirmed that there were strong absorption bands at 900 and 976.4 nm and strong emission band at 976.4 nm in Yb/sup 3+/ ion doped YCa₄O(BO₃)₃ crystal. For the application of second harmonic generation of 1.064 ㎛ laser, non-linear optical devices with θ=32.32° and Ψ=0°, λ/10 of flatness and the size of 6x8x5.73 mm were fabricated from the grown YCa₄O(BO₃)₃ crystal.

• Journal of the Korean housing association
• /
• v.8 no.3
• /
• pp.153-162
• /
• 1997

Personalities. human relations. living patterns. and so on of the aged have been moulded respectively for a long period of time and their present situation of health. family make-up. economic condition etc. are different individually. Various characteristics - physiological. psychological and social peculiarities - of the aged are analyzed and studied in preceding paper to grope planning factors of architectural spaces by referring to sundry records from many branch gerontology, medical science. psycology. sociology. etc. - of knowledge in a position of architectural planning. So. in this paper. the directions of planning residential environment for the aged are studied on the base of those planning factors of architectural spaces. there are room(X$_1$). unit home(X$_2$), public housing(X$_3$), residential district(X$_4$) as dwelling spaces for the aged in X axis and safety(Y$_1$). hygiene(Y$_2$). convenience (Y$_3$), comfortableness (Y$_4$). psychology ($Y^5$), aesthetics ($Y^6$). society ($Y^7$). economy ($Y^8$) as the terms desired to spaces in Y axis. And the directions of planning residential environment for the elderly are studied by discussing mutual matters relevant to the subject on the cells of matrix formed by X. Y axis. In planning residential environment for the elderly. their physiological. psychological. social characteristics should be considered thoroughly and many types of dwelling spaces should be built. Then they can take up their abode to suit their conditions easily.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.8
• /
• pp.894-900
• /
• 2006

The electrical characteristics associated with crystal structure changes as a function of La content for $(Pb_{1-x}La_x)(Zr_{0.5}Ti_{0.5})O_3$ thin films were investigated for applications in memory capacitors. Tetragonality of PLZT films decreased with increasing La content. Thin films with La $\geq$ 20 mol% were found to be cubic. Films with La $\geq$ 12 mol% exhibited broader dielectric peaks compared to those of bulk ceramics and behaved as relaxer ferroelectrics. Tetragonal PLZT film with 12 mol% La had a dielectric constant maximum of 1330 at room temperature and a charge storage density of ${\sim}18{\mu}C/cm^2$ at 5 V. Decrease in coercive field and remnant polarization with increase in La content were resulting from less dipolar response caused by the decreased crystal anisotropy. The leakage current densities $<10^{-8}A/cm^2$ up to 5 V bias voltage were observed for the films with La $\geq$ 14 mol%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.05a
• /
• pp.46-50
• /
• 1996

In this paper, xPb(Zn$\_$1/3/Nb$\_$2/3/)O$_3$-yPbTiO$_3$-zPbZrO$_3$-zPbZrO$_3$ (0.5wt%)MnO$_2$ ceramics were fabricated by the mixed oxide method sintered at 1250$^{\circ}C$ for 2[hrs] and then the dielectric and pyroelectric properties were investigated. In 0.10PZN-0.45PT-0.47PZ sample, dielectric constant was 829 and in the case of 01.5PZN-0.45PT-0.40PZ sample, pyroelectric current and pyroelectric coefficient were 0.95 x 10$\^$-7/ [A] and 7.6 x 10$\^$-1/ [C/$\textrm{cm}^2$$.$$^{\circ}C$]. Figure of merits of pyroelectric current and voltage and detectivity, in same sample, has shown good properties, that were 2.4 x 10$\^$-8/[C$.$cm/J], 5.5 x 10$\^$-11/[C$.$cm/J], 1.6 x 10$\^$-8/ [C$.$cm/J].

• Korean Journal of Materials Research
• /
• v.10 no.2
• /
• pp.166-170
• /
• 2000

Nuclear fuel $UO_{2+x}$ power was produced from concentrated $UF_6$ by the DCP(Dry Conversion Process). The characterstics of $UO_{2+x}$ powder, prepared with respect to steam flowing conditions and temperature variations in a rotary kiln reactor, have been investigated with a uranium analyzer, water vapor measurement, and SEM. Fluorine content of the powder could be reduced to 8ppm. The moisture content was found to be optimized.

• Current Photovoltaic Research
• /
• v.8 no.2
• /
• pp.60-65
• /
• 2020

In perovskite solar cells with planar heterojunction configuration, selection of proper charge-transporting layers is very important to achieve stable and efficient device. Here, we developed solution processible Cu doped NiO_x (Cu:NiO_x) thin film as a hole-transporting layer (HTL) in p-i-n structured methylammonium lead trihalide (MAPbI₃) perovskite solar cell. The transmittance and thickness of NiO_x HTL is optimized by control the spin-coating rate and Cu is additionally doped to improve the surface morphology of undoped NiO_x thin film and hole-extraction properties. Consequently, a perovskite solar cell containing Cu:NiO_x HTL with optimal doping ratio of Cu exhibits a power conversion efficiency of 14.6%.