• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.657-661
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• 2002

PZT powder was prepared by partial oxalate method using $(Zr_{0.53}Ti_{0.47})O_2$, $Pb(NO_3)_2$ and $(COOH)_2{\cdot}2H_2O$ as a precipitant. $Nb_2O_5$ additive effect on microstructure and piezoelectric properties of PZT ceramics were investigated. The coexistence of rhombohedral and tetragonal phases of PZT ceramics at the sintering temperature of $1100^{\circ}C$ was revealed from the X-ray diffraction patterns. The grain size PZT ceramics was decreased with the increase $Nb^{5+}$. and the sinterbility of PZT ceramics was decreased with the increase $Nb^{5+}$ addition. The electromechanical coupling factors $K_p$ show above 0.60 at $1100^{\circ}C$ sintering temperature by $Nb_2O_5$ addition above 0.6mol%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.375-378
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• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.61-64
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• 2004

In this paper, we investigated the variations of initial fault current limiting instant according to fault angles in the flux-lock type SFCL. The flux-lock type SFCL consists of the coil 1 and the coil 2 that are wound in parallel each other through an iron core. The operation of the flux-lock type SFCL can be divided into the subtractive polarity winding and the additive polarity winding operations according to the winding directions between the coil 1 and coil 2. The subtractive polarity winding operation could be analyzed with three modes. On the other hand, the additive polarity winding operation could be analyzed with five modes. The variations of initial fault current limiting instant in two winding directions were dependent on the fault angles. It was confirmed from experiment that the fault current limiting instant was getting faster and the magnitude of fault current at the initial fault time was getting higher for higher fault angle.

• 한국정밀공학회지
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• 제31권12호
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• pp.1077-1083
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• 2014

Multi-material Additive Manufacturing (AM) is being focused to apply for direct manufacturing of a product. In this paper, a three-dimensional circuit device (3DCD) fabrication technology based on the multi-material AM technology was proposed. In contrast with conventional two-dimensional Printed Circuit Board (PCB), circuit elements and conducting wires of 3DCD are placed in threedimensional configuration at multiple layers of the structure. Therefore, 3DCD technology can improve design freedom of an electronic product. In this paper, 3DCD technology is proposed based on AM technology. Two types of 3DCD fabrication systems were developed based on the Stereolithography and the Fused Deposition Modeling technologies. And the 3DCD samples which have same function were fabricated, successfully.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.123-126
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• 2003

The electrophoretic deposition method using the suspension solution with additives under the electric potential was applied for the fabrication of YBCO superconductor wire. This method was able to simplify the fabrication facilities, and produce an uniform and dense thick film. To improve the critical current density of deposited films, the additive PEGs(Poly Ethylene Glycole) with the molecular weight of 600, 1000 and 3400, were used as chemical binders for the suspension solution. The organic additive PEG showed better effects to the properties of YBCO superconductor wire. The PEG improved the adhesion between superconductor particles and suppressed the crack on the surface, which enhanced the surface uniformity and density of YBCO deposited film. It was found that acetone suspension solution showed better deposition properties than the others. The samples fabricated in the solution with the additive, 8 vol.% of 1% PEG(1000), showed the highest critical current density measured as $2300{\sim}2400\;Acm^2$ at 77 K, 0 T.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.960-966
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• 2004

On the bases of the results from "Additive Coating of BaTiO$_3$ Powder using Sol Coating Method I", experimental condition was defined. Representative additives for BaTiO$_3$, that is to say, Mg, Ca and Mn were experimented. The sources of the metal ion were used by organometal complex. As added it, the stability of BaTiO$_3$ sol was evaluated. Mg and Ca were stable, however, The solubility limit of Mn-ATH was 0.05 mol ratio in Mn-ATH/sol. The solubility limit of Mg ion in BaTiO$_3$ was lower than 2 mol%. From the x Ray diffraction patterns, lattice parameters were different with temperature and additives, because the solubility of metal ion was varied in BaTiO$_3$. The dielectric constant of BaTiO$_3$ powders which coated with the 1.5 mol% Mg and calcined at 1200$^{\circ}C$ was increased with 20%.

• Journal of Welding and Joining
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• 제35권2호
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• pp.6-12
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• 2017

Ti-alloys have high specific strength and are widely used for the filed of space aeronautics plant. However, it is difficult to process Ti-Alloys due to its high yield strength and it cannot raise the machining speed because it has a possibility of catching fire while processing. In order to reduce the number of processes for the Ti-alloys, the researches related to Additive Manufacturing(AM) have been actively carried out at the moment. As for the initial stage of AM market related to Ti-alloys, it started to use the raw material of powder metal, and it is currently being developed based on welding. In this study, Interpass peening reduced the size of the primary ${\beta}$ grain in the z-axis direction, increased the nucleation site of ${\alpha}-colony$, and decreased the length and width of ${\alpha}$ laths as though interpass rolling. Interpass peening leads to an increase in yield/ultimate tensile strength without decrease elongation, resulting decrease in anisotropy of the material.

• 한국전기전자재료학회논문지
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• 제29권2호
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• pp.110-113
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• 2016

(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of $(YNdSm)_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting $(YNdSm)_2BaCuO_5$ inclusions of the melt-textured (YNS)1.8 sample with $CeO_2$ additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without $CeO_2$ additive, showed an onset $T_c{\geq}90K$ and sharp superconducting transition. The critical current density $J_c$ value of the (YNdSm)1.8 superconductor with $CeO_2$ additive were 840 A, $1.2{\times}104A/cm^2$ in 77 K, 0 Tesla by direct current transport method.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.308-313
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• 2002

Samples with the norminal composition, $Bi_{2-x}Au_xSr_2CaCu_2O_{8+\delta}$ (x = 0, 0.05. 0.1, 0.15) were prepared by the solid-state reaction method. The superconducting properties, x-ray powder diffraction patterns, critical temperature and microstructure of surface were measured the samples. x-ray patterns show the single phase(2212) nature of the samples. But, the peaks of 2201 at $2\theta=30^{\circ}$ and Au peak at $2\theta=38.31^{\circ}$ are observed in the Au additive samples. The grain sire are enlarged with the increase of x. As the result of enlargement the grain size, the onset and offset critical temperature($T_c^{on}$,$T_c^{zero}$) increased with increase of x.

• 한국전기전자재료학회논문지
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• 제28권9호
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• pp.607-614
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• 2015

To provide the clear images from the direct light on electrical board and display devices, anti glare treatment of display cover glass is needed. In this study, the effects of surface treatment temperature, concentration, and etching solution coating thickness of the gel phase on optical elements control such as gloss, haze of reflected light and transmittance, were investigated. Cover glasses were treated at different coating thickness and additive concentration. The optical properties were examined using spectrophotometer, gloss and haze meter. The surface morphology and roughness were measured by the optical microscope and Ra measuring instrument. The etching rate and surface morphologies were dramatically affected by the concentration of acid additive in the viscous gel because of re-crystallization of components in the etching solution, hydrogel formation and coagulant after coating on glass substrate. In our experimental range, cover glass which is surface-treated with various optical properties as well as the morphology uniformity was obtained; in particular, optical properties could be controlled by etching solution coating thickness of the gel phase and the concentration of additive. The gloss was depended on the surface roughness and it showed the linear relationship between optical transmittance and haze of reflected light, respectively.