• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.6
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• pp.361-366
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• 2014

$MnO_2$-doped $0.985[Li_{0.04}(Na_{0.545}K_{0.46})_{0.96}(Nb_{0.81}Ta_{0.15}Sb_{0.04})]O_3+0.015KNbO_3(0.985LNKNTS+0.015KNbO_3)$ lead-free ceramics were fabricated by conventional solid state method to develop excellent dielectric and piezoelectric properties. The result of X-ray diffraction patterns obviously indicated that all of the specimen has pure perovskite structure without secondary phase. In addition, orthorhombic phase and coexistance region of orthorhombic-tetragonal phase (MPB) were observed with amount of $MnO_2$. The optimal values of ${\rho}$=4.70 $g/cm^3$, $d_{33}=238$ pC/N, $k_P=0.46$, $Q_m=121$, ${\varepsilon}_r=849$, and $T_C=225^{\circ}C$ were obtained at 0.01 mol% $MnO_2$ doped $0.985LNKNTS+0.015KNbO_3$ ceramics sintered at $990^{\circ}C$ for 5 h, respectively. Hence, it was indicated that the suitable amount of $MnO_2$ could improve the electrical properties of $0.985[Li_{0.04}(Na_{0.545}K_{0.46})_{0.96}(Nb_{0.81}Ta_{0.15}Sb_{0.04})]O_3+0.015KNbO_3$ ceramics.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.140-142
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• 2011

• Bulletin of the Korean Chemical Society
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• v.15 no.7
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• pp.545-549
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• 1994

Using the extended Hackel molecular orbital method in connection with the tight binding model, we have studied electronic structure and related properties of the charged cluster models relating to superconducting $YBa_{2}Cu_{3}O_{7-x}$, crystals in which O-atoms in regular sites were selectively replaced with Se atoms. In analogy to the isomorphism problem with molecules, we discuss all possible combinations of Se-substitutions in O-sites with one, two, and four Se atoms. The calculations are carried out within charged cluster models for analogues of YBa-copper oxide. Our results suggest that the electronic structure of the symmetrically Se-substituted or Se-added compound is closer to that of the YBCO superconducting compound than that obtained from the unsymmetrical substitution. This applies in particular if O is replaced with Se around the Cu(1) site. Symmetrical substitutions in the $CuO_2$ layers give rise to large variations in the electronic structure of $YBa_{2}Cu_{3}O_{7}$. This is consistent with the fact that superconductivity is very sensitive to the electronic population of the $CuO_2$ layers.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.322-327
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• 2000

This paper investigates the time-dependent crack growth in X20CrMoV 12 1 steel weld joints. Crack growth test are carried out $545^{\circ}C$ on side-grooved 1/2T CT specimens under static loads. A simulated material is produced for the intercritical HAZ, where fracture normally occurs. Constitutive properties are obtained for the simulated HAZ material as well as for the base metal and weld metal. Finite element analyses of crack growth are performed on the models with and without a HAZ layer, using the experimental crack length-time history. The inclusion of HAZ layer increase the load line velocities significantly. The crack growth rates are correlated reasonably well with $C^*$. The smallest crack size for the validity of $C^*$ is found much smaller than the ASTM crack initiation size for 1T CT specimen of creep ductile materials.

• Macromolecular Research
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• v.11 no.3
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• pp.194-197
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• 2003

A new 2,5-di(t-octylphenoxy) group substituted poly(p-phenylenevinylene) derivative was synthesized by Gilch polymerization. The obtained polymer was characterized by NMR, FT-IR, and chemical analysis and completely soluble in common organic solvents. The polymer showed good thermal stability with T$_{g}$ of 105$^{\circ}C$. The polymer dissolved in chloroform showed maximum emission at 514 nm with a shoulder peak at around 560 nm. The EL spectrum of the ITO/PEDOT/TOP-PPV/Al device was observed maximum emission at 545 nm with a shoulder peak at around 585 nm.m.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.545-545
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• 2003

Chitosan is applied as a dressing for oral mucous wound and a tampon following radical treatment of maxillary sinus. Furthermore, it is being investigated as an absorbing membrane for endodontic and periodontic surgeries. A few studies have reported osteoconduction and osteogenesia at the site of chitosan implant in vivo. However, compared with soft tissue healing processes, the mechanisms concerning effects of chitosan for biological mineralization have not yet been resoil In the present study, we studied the gene expression pattern using cDNA microarray and RT-PCR analyses in hard tissue forming osteoblasts cultured with water-soluble and low molecular weight chitooligosaccharide. cDNA microarray analysis revealed that 16 genes were expressed at 〉1.5-fold higher signal ratio levels in the experimental group compared with the control group after 3 days. RT-PCR analysis showed that chitosan oligomer induced an increase in the expression of two genes, CD56 antigen and tissue-type plasminogen activator. Furthermore, the expression of mRNAs for BMP-2 was almost identical in the experimental and control groups after 3 days of culture, but slightly increased after 7 days of culture with chitosan oligomer. These results suggest that a super-low concentration of chitooligosaccharide could modulate the activity of osteoblastic cells through mRNA levels and that the genes concerning cell proliferation and differentiation can be controlled by water-soluble chitosan.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.545-550
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• 2013

Piezoelectric PMN-29PT single crystal multilayer actuators [100 $mm^2$ in cross section and 22 mm in length] are designed and fabricated by stacking square plates [$10{\times}10{\times}0.5(t)\;mm^3$] of PMN-29PT single crystals having a $d_{33}$ of about 1,500 pC/N. The characteristics of PMN-29PT multilayer actuators are compared with those of P-025.40P multilayer PZT ceramic actuators [490 $mm^2$ in cross section and 60 mm in length] produced by PI in Germany. Even though the total volume of the PMN-29PT single crystal multilayer actuator is only about 7.5% of that of the P-025.40P ceramic multilayer actuator, PMN-29PT single crystal multilayer actuators are expected to show very similar properties to P-025.40P ceramic actuators in terms of static stroke and blocking force. Therefore, on the basis of their smaller mass and volume compared to the conventional PZT ceramic multilayer actuators, piezoelectric PMN-29PT single crystal multilayer actuators have significant potential regarding the development of various high performance actuators for aerospace subsystems.

• Computers and Concrete
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• v.13 no.4
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• pp.531-545
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• 2014

The purpose of this paper is to develop a prediction model for the compressive strength of waste LCD glass applied in concrete by analyzing a series of laboratory test results, which were obtained in our previous study. The hyperbolic function was used to perform the nonlinear-multivariate regression analysis of the compressive strength prediction model with the following parameters: water-binder ratio w/b, curing age t, and waste glass content G. According to the relative regression analysis, the compressive strength prediction model is developed. The calculated results are in accord with the laboratory measured data, which are the concrete compressive strengths of different mix proportions. In addition, a coefficient of determination $R^2$ value between 0.93 and 0.96 and a mean absolute percentage error MAPE between 5.4% and 8.4% were obtained by regression analysis using the predicted compressive analysis value, and the test results are also excellent. Therefore, the predicted results for compressive strength are highly accurate for waste LCD glass applied in concrete. Additionally, this predicted model exhibits a good predictive capacity when employed to calculate the compressive strength of washed glass sand concrete.

• Journal of fish pathology
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• v.26 no.3
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• pp.149-161
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• 2013

Viral haemorrhagic septicaemia virus (VHSV), the causative agent of viral haemorrhagic septicaemia (VHS), is an epidemic virus of cultured olive flounder Paralichthys olivaceus in Korea. In the present study, the entire glycoprotein (G) gene including several hypervariable regions from 36 isolates of diverse geographic and host origin and 8 Korean VHSV isolates from cultured olive flounder were analyzed. Phylogenetic analysis indicated that most of Asian VHSV belong to the genotype IVa group, suggesting that they originated from a common ancestral virus. Comparative sequence analysis of the complete G protein from Korean VHSV isolates revealed 3 Korean strain-specific nucleotide residues (nucleotide number of G-region: A755, T834 and T1221). These results suggest that Korean VHSV originated from a common ancestor, but these regional specific nucleotide sequences suggest that genetic differences of VHSV are more related to geographic areas than to host fish species.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1050-1053
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• 2006

We fabricated white organic light emitting diodes consisting of three emitting layers of red-emitting DCM2 doped ${\alpha}-NPD$, blue-emitting DPVBi and green-emitting C545T doped Alq3. By optimizing the thickness of the hole-transport layer of ${\alpha}-NPD$ and the electron-transport layer of Alq3, efficient white OLEDs were obtained with a luminous efficiency of 4.40lm/W at luminance of $1000cd/m^2$, and a max-imum luminance of $51,939cd/m^2$