• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
• /
• pp.157-160
• /
• 2001

We have investigated the Dielectric and Piezoelectric properties of $xPb(R_{1/2}Ta_{1/2})O_3-(1-x)Pb(Zr_{0.52}Ti_{0.48})O_3$ (R=Al,Y) solid solutions in which R ions are substituted for Al and Y ions. The maximum value of electromechanical coupling factor kp of 55% and 51% were obtained at the composition of 5mol% PAT and 5mol% PYT. However mechanical quality factor$(Q_m)$ had a minimum value of 44 and 69 at the composition of 5mol% PAT and 5mol% PYT. Also, the maximum value of piezoelectctric constant of $d_{33}(329[pC/N])$ and $d_{33}(310[pC/N])$ were obtained at the composition of 5mol% PAT and 5mol% PYT.

• Journal of IKEEE
• /
• 제23권3호
• /
• pp.768-776
• /
• 2019

With the deployment of 4-th generation industrial revolution, the computer based manufacturing technologies employing advanced IT technology are much more popular than any other past years. In this research, some novel S/W technologies related to the industrial X-ray CT (computed tomography) for the inspection of the industrial parts are introduced. First, newly constructed industrial X-ray CT is presented in this paper, where some basic principles and functions of the CT are described. Then some research platforms are developed to generate more advanced functionalities of the industrial CT. Especially, the data transform from CT to general S/W such as Matlab is conducted. And based on this techniques, some supplementary S/W platform such as GUI (graphical user interface) of the CT S/W and some 3D voxel based image processing technologies can be developed in this paper. The industrial CT is one of the rare research items and it's values can be much more enhanced when it is used with advanced IT technologies.

• Korean Journal of Crystallography
• /
• 제13권1호
• /
• pp.25-30
• /
• 2002

The M/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O (M = Ca and Sr) solid solution systems have been shown interstitial solid solutions and continuous substitutional solid solutions. The symmetry around the Eu site of yEu/sup 3+/ : M/sub 1-x/Na/sub 2x/Al/sub 2-y/Mg/sub /(BO₃)₂O (M = Ca and Sr) changes the intensities and the chromaticities of transitions. The Eu/sup 3+/ion can be very bright and efficient and have the desired emission wave-length depending on the site symmetry of the Eu/sup 3+/ion site. As the amount of Na in the Eu/sup 3+/ion doped Ca/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O system increases, the Eu site symmetry is going to be a noncentrosymmetric site. With increasing x, the decreased intensity in the /sup 5/D/sub 0/→/sup 7/F₁(590 nm) transition relates to the low symmetry of the Eus/up 3+/-doped Ca/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O system, because of the Ca-centered octahedron in the CaAl₂(BO₃)₂O compound. The SrAl₂(BO₃)₂O compound also provides an improved chromaticity due to the lower site symmetry of Eu/sup 3+/ion.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
• /
• pp.229-232
• /
• 1999

We have measured the temperature dependence of thermoelectric power (TEP) and resistivity for the Sr$_{1-x}K_xBiO_3$ superconductor (x=0.45-0.6). At T=10.2K, the resisitivity starts to increase from zero and a rather broad superconducting phase transition (${\Delta}$T ${\sim}$ 2.3K) is observed. TEP at room temperature has a small negative value ( S =-1.96${\mu}$V/K), characteristic of metallic-like TEP. The temperature dependence of TEP shows two distinct features. With decreasing temperature from room temperature, the absolute value of TEP decreases and the sign of TEP changes from negative to positive around 200k. Also, the negative slope of TEP(dS/dT) decreases substantially and becomes rather flat at around 160k, which is a feature already noted in Ba$_{1-x}K_xBiO_3$[1].

• Bulletin of the Korean Mathematical Society
• /
• 제47권3호
• /
• pp.551-561
• /
• 2010

In this paper we give a new characterization of real hypersurfaces of type B, that is, a tube over a totally geodesic $\mathbb{Q}P^n$ in complex two-plane Grassmannians $G_2(\mathbb{C}^{m+2})$, where m = 2n, with the Reeb vector $\xi$ belonging to the distribution $\mathfrak{D}$, where $\mathfrak{D}$ denotes a subdistribution in the tangent space $T_xM$ such that $T_xM$ = $\mathfrak{D}{\bigoplus}\mathfrak{D}^{\bot}$ for any point $x{\in}M$ and $\mathfrak{D}^{\bot}=Span{\xi_1,\;\xi_2,\;\xi_3}$.

• Transactions of Materials Processing
• /
• 제33권2호
• /
• pp.123-131
• /
• 2024

Plastic, the main material of FFF-type 3D printing, exhibits lower strength compared to metal. research aimed at increasing strength is needed for use in various industrial fields. This study analyzed three X-shape infill patterns(grid, lines, zigzag) with similar internal lattice structure. Moreover, tensile test considering weight and printing time was conducted based on the infill line multiplier and infill overlap percentage. The three X-shape infill patterns(grid, lines, zigzag) showed differences in nozzle paths, material usage and printing time. When infill line multiplier increased, there was a proportional increase in tensile strength/weight and tensile strength/printing time. In terms of infill overlap percentage, the grid pattern at 50% and the zigzag and lines patterns at 75% demonstrated the most efficient performance.

• Journal of Magnetics
• /
• 제19권3호
• /
• pp.221-226
• /
• 2014

Significantly enhanced low-field magnetoresistance (LFMR) and maximum dMR/dH {$(dMR/dH)_{max}$} values were successfully achieved from $La_{0.7}Sr_{0.3}MnO_3$(LSMO)-manganese oxide composite samples prepared by liquid phase sintering, compared with those of the same composites prepared by solid state reaction. For this study, pure LSMO and LSMO-manganese oxide composites with various nominal compositions of (1-x)LSMO-$xMn_2O_3$ (x = 0.1, 0.2, 0.3, 0.4, and 0.8) were sintered at $1450^{\circ}C$, above the eutectic temperature of $1430^{\circ}C$, for 1 h in air. The highest LFMR value of 1.28% with the highest $(dMR/dH)_{max}$ value of 21.1% $kOe^{-1}$ was obtained from the composite sample with x = 0.3 at 290 K in 500 Oe. This enhancement of LFMR and $(dMR/dH)_{max}$ values is ascribed to efficient suppression of magnetic disorder at the LSMO grain boundary, by forming a characteristic LSMO-manganese eutectic structure.

• Journal of the Korea Society of Computer and Information
• /
• 제28권9호
• /
• pp.105-111
• /
• 2023

Currently, most of content restoration using artificial intelligence learning is 2D learning. However, 3D form of artificial intelligence learning is in an incomplete state due to the disadvantage of requiring a lot of computation and learning speed from the existing 2 axes (X, Y) to 3 axes (X, Y, Z). The purpose of this paper is to secure a data-set for artificial intelligence learning by analyzing and 3D modeling the stone pagodas of ourinari by era based on the two-dimensional information (image) of cultural assets. In addition, we analyzed the differences and characteristics of towers in each era in Korea, and proposed a feature modeling method suitable for artificial intelligence learning. Restoration of cultural properties relies on a variety of materials, expert techniques and historical archives. By recording and managing the information necessary for the restoration of cultural properties through this study, it is expected that it will be used as an important documentary heritage for restoring and maintaining Korean traditional pagodas in the future.

• Bulletin of the Korean Chemical Society
• /
• 제5권1호
• /
• pp.3-16
• /
• 1984

The effect of solvent on the dipole moments for (chloromethyl) stannanes has been investigated by applying EHT calculation for the isomers of trigonal bipyramidal Sn(Ⅳ)$Cl_4X$ and $Cl_n$Sn(Ⅳ) $(CH_2Cl)_{4-n}$, octahedral Sn(Ⅳ)$Cl_42X$ and $Cl_nSn$(Ⅳ)$(CH_2Cl)_{4-n}$ 2X type complexes in dioxane and ethylacetate solutions (X: dioxane or ethylacetate). For Sn(Ⅳ)$Cl_4$ in dioxane solution, the calculated dipole moment for the trigonal bipyramidal Sn(Ⅳ)$Cl_4X$ type complex [isomer (b)] is closer to the experimental dipole moment than octahedral Sn(Ⅳ)$Cl_4X$2X type complexes. This calculated dipole moment suggests that Sn(Ⅳ)$Cl_4X$ may have the trigonal bipyramidal structure in dioxane solution. However, the calculated dipole moment for octahedral $Cl_3$Sn(Ⅳ) ($CH_2$Cl)2X type complex [Isomer (d)], ClSn(Ⅳ)(CH2Cl)32X type complex [Isomer(k)] and Cl2Sn(Ⅳ)(CH2Cl)22X type complex [Isomer(h)] are closer to the experimental dipole moments than other isomers for octahedral complexes and trigonal bipyramidal complexes. Such theoretical results indicate that $Cl_3Sn$(Ⅳ )($CH_2Cl$), ClSn(Ⅳ)$(CH_2Cl)_3$ and $Cl2Sn$(Ⅳ)$(CH_2Cl)_2$ complexes may have octahedral structures, Isomer(d), (k) and (h) in ethylacetate solution, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• 제11권1호
• /
• pp.6-13
• /
• 2001

By using a vertical Bridgeman method, single crystalline structures of $Mg_xZn_{1-x}Te(0{\le}X{\le}0.48)$ were grown for various Mg mole compositions. With the increasing Mg fraction, the lattice constant is linearly increased from 6.103 to 6.239$\AA$ for the range of $0{\le}X{\le}0.48$ and the lattice constant of zincblende MgTe was linearly extrapolated to the value of 6.433$\pm$0.002$\AA$. The optical properties of the crystalline structure were characterized with photocurrent measurements. As a results of photocurrent spectra, the single crystalline $Mg_xZn_{1-x}Te$ show the energy bandgap of 2.380 and 2.260eV at 4.2 and 294 K, respectively. The photocurrent peak blueshifts with increasing Mg mole fraction and show the linear dependence of energy bandgap, $E_g$(X)=b+(0.8)X. The extrapolation shows the energy bandgaps of MgTe of 3.18 and 3.06eV at the temperatures of 4.2 and 294K, respectively. Furthermore, the photocurrent peaks redshifts with increasing temperature and the temperature coefficient is given to the value of $dE_g$/dT=-(5.6~$6.1){\times}10^{-4}$eV/K. for the temperature range above 100K.