• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.334-335
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• 2005

Ternary tellurite glassy systems ($Li_2O-V_2O_5-P_2O_5$) have been synthesised using Vanadium oxide as a network former and Lithium oxide as network modifier. The addition of a metal? oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode' materials for solid-state batteries. This glass-ceramics crystallized from the $Li_2O-V_2O_5-P_2O_5$ system are particularly interesting, because they exhibit high conductivity (up to $5.95\times10^{-4}$ S/cm) at room temperature. the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric D.C conductivity result have been analyzed in terms of a small polaron-hopping model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.690-693
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• 2015

In this paper, in order to develop excellent Pb-free composition ceramics for ultrasonic sensor. The $SnO_2$-doped ($Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3$)(abbreviated as NKL-NST) ceramics have been synthesized using the ordinary solid state reaction method. The effect of $SnO_2$-doping on their dielectric and piezoelectric properties was investigated. The ceramics doped with 0 wt% $SnO_2$ have the optimum values of piezoelectric constant($d_{33}$), piezoelectric figure of merit($d_{33}.g_{33}$), planar piezoelectric coupling coefficient($k_p$) and density : $d_{33}=195[pC/N]$, $d_{33}.g_{33}=5.62pm^2/N.kp=0.40$, $density=4.436[g/cm^3]$. suitable for duplex ultrasonic sensor application.

• Clean Technology
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• v.16 no.2
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• pp.95-102
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• 2010

Sulfonic acid (-SO3H) functionalized mesoporous silica containing HMS, SBA 15(S15), MCM 41(M41) were synthesized by post-synthesis and co-condensation method. Their catalytic performance is tested by dehydration reaction of D-xylose to furfural. As a result, good conversion and selectivity was obtained using water as an environmentally friendly solvent. Additionally, increased amounts of sulfuric acid in catalysts resulted in improved conversion of D-xylose. All of the acid-functionalized mesoporous silica showed higher selectivity than other solid acids such as ${\gamma}-Al_{2}O_{3}$ and zeolite.

• Korean Journal of Materials Research
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• v.13 no.2
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• pp.115-119
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• 2003

The thick film type sensor having Pt/Na Super Ionic Conductor(NASICON) solid electrolyte/Pt/$Na_2$$SO_4$/Pt catalyst system for $SO_2$gas was fabricated by screen-print method. The phase of Na Super Ionic Conductor solid electrolyte sintered at different temperature of 1050, 1150,$ 1250^{\circ}C$ and for different time of 1.5, 2.5, 3.5 hr were investigated by XRD. The Electromotive Force variation of the sensor with $SO_2$concentrations and operating temperatures were investigated. The major phase of Na Super Ionic Conductor film sintered at 115$0^{\circ}C$ for 3.5 hr was sodium zirconium silicon phosphate($Na_3$Zr$_2$$Si_2$PO$_{12}$). The Nernst's slope of Na Super Ionic Conductor sensor for $SO_2$gas with the variation of concentration from 10 to 100 ppm was 167.14 ㎷/decade at the operating temperature of $500 ^{\circ}C$. The increase of oxygen partial pressure was not affected to the variation of Nernst's slope.e.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.627-635
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• 2020

3D printing technology is a processing technology in which 3D structures are formed by fabricating multiple 2D layers of materials based on 3D designed digital data and stacking them layer by layer. Although layers are stacked using inkjet printing to release various materials, it is still rare for research to successfully form a product as an additive manufacture of multi-materials. In this study, dispersion conditions are optimized by adding a dispersant to an acrylic monomer suitable for inkjet printing using Co₃O₄ and Al₂O₃. 3D structures having continuous composition composed of a different ceramic material are manufactured by printing using two UV curable ceramic inks whose optimization is advanced. After the heat treatment, the produced structure is checked for the formation and color of the desired crystals by comparing the crystalline analysis according to the characteristics of each part of the structure with ceramic pigments made by solid phase synthesis method.

• Korean Journal of Agricultural Science
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• v.51 no.3
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• pp.391-398
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• 2024

A total of 10 sows (average body weight of 185.5 kg, Landrace × Yorkshire) and their progenies were utilized in this experiment. At first, sows were randomly allotted to 1 of 2 dietary treatments with 5 replicates of 1 sow and its litter per pen following a randomized complete block design. The test treatments were: Control (CON) basal diet and a basal diet supplemented with 0.036% of 25-hydroxyvitamin D₃ (25(OH)D₃). Sows fed diet supplemented with 25(OH)D₃ had no adverse effect on their reproduction performance such as body weight, average daily feed intake, body weight loss, and body weight loss difference during before farrowing, after farrowing, and at weaning. Piglets born from sows fed dietary 25(OH)D₃ showed significantly increased (p < 0.05) weaning weight and average daily gain. Sows fed diet supplemented with 25(OH)D₃ had high total solid (TS) colostrum concentration at week 1, however at the end of week 3 the TS level had decreased approximately 2%. We believe that the positive findings of the present study could establish a major constituent for the swine mammary secretions and provide a reliable groundwork for future experiments in animal husbandry.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.920-923
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• 2000

All solid-state thin film supercapacitor(TFSC) based on $RuO_2$ electrode was fabricated. Ruthenium oxide$(RuO_2)$ thin film was deposited on Pt/Ti/Si subsrate by d.c. magnetron sputtering. LiPON(lithium phosphorus oxynitride) thin film were deposited by r.f. reactive sputtering. X-ray diffraction patterns of $RuO_2$ and LiPON films revealed that crystal structures of both films were amorphous. To decrease resistivity of $RuO_2$ thin film, $RuO_2$ thin film was deposited with $H_2O$ vapor. In order to decide the maximum ionic conductivity, the LiPON films were prepared by various sputtering condition. The maximum ionic conductivity was $9.5\times{10}^7S/cm$. A charge-discharge measurements showed the capacity of $3\times{10-2}\;F/cm^2-\mu{m}$ for the as-fabricated TFSC. The discharging efficiency was decreased after 500 cycles by 40 %.

• Journal of Magnetics
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• v.11 no.4
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• pp.151-155
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• 2006

The electromagnetic engine valve actuator is a key technology to achieve variable valve timing in internal combustion engine and the steel core and clapper of the electromagnetic engine valve actuator are laminated to reduce the eddy current loss. To design and characterize the performance of the electromagnetic engine valve actuator, FE (finite element) analysis is the most effective way, but FE (finite element) 3-D modeling of real lamination needs very fine meshes resulting in countless meshes for modeling and numerous computations. In this paper, the equivalent FE 2-D model of electromagnetic engine valve actuator is introduced and FE analysis is performed using the equivalent FE 2-D model.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.76-81
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• 2006

In this paper, profile error measurement method of a turbine blade using 3D-scanner is developed. The method begins with scanning the upper and lower sides of the blade on which three small balls are attached, and constructs a solid measurement model by registering the two scanned surfaces. Airfoils are derived from the model at each interval by intersecting it with a plane, and arranged with design airfoils. The $2^2$ factorial design search method is engaged in arranging the two airfoils, from which the main blade parameters including the edge radius are computed. The developed measurement technique is applied to practical blade manufacturing and validates its effectiveness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.44-49
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• 1999

In this study, microstructure and electrical conductivity of {(G $d_2$ $O_3$)$_{0.75}$( $Y_2$ $O_3$)$_{0.25}$}$_{x}$ (Ce $O_2$)$_{1-x}$ (0.01$\leq$x$\leq$0.25) was investigated as a function of composition x. GYO addition(x) increased the bulk density and G $d_2$ $O_3$ was found to be monoclinic at x>0.15. From the change of the lattice parameter with the addition(x), GYO solution limit for ceria was exceeded in the range of x=0.05 to 0.09. Thermal expansion coefficient(15~17$\times$10$^{-6}$ $^{\circ}C$) of GYC samples at x=0.01 to 0.07 was higher in value than that of 8YSZ(10.8$\times$10$^{-6}$ $^{\circ}C$). The electrical conductivity of GYC samples at x=0.05 showed the maximum(0.01S/cm) in value at 1073K which was 2 times higher than that of 8YSZ. The activation energy for the electrical conduction was determined to be 0.60eV in the temperature range of 1073K.3K..3K.