• Journal of the Korean Ceramic Society
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• v.45 no.12
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• pp.760-765
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• 2008

In this study, the effects of small amounts (${\leq}3\;mol%$) of Li doping on the sintering characteristics and electrochemical performance of $(ZrO_2)_{0.89}(ScO_{1.5})_{0.1}(CeO_2)_{0.01}$ (ScSZ) were investigated. By adding 3 mol% lithium, the densification temperature of ScSZ was reduced from the conventional temperature of $1400^{\circ}C$ to $1200^{\circ}C$. It was found that Li doping also led to changes in the Zr:Sc ratio at the grain boundaries. Correspondingly, the dispersion of lithium zirconia at the grain boundaries accelerated the growth of ScSZ grains and increased the grain boundary resistance at temperatures below $450^{\circ}C$. At elevated temperatures of $450{\sim}750^{\circ}C$, the electrical conductivity of the ScSZ after doping remained almost unchanged under air and reducing atmospheres. These results suggest that the addition of lithium is promising for use in low temperature co-firing of ScSZ-based components for intermediate temperature solid oxide fuel cells.

• Korean Journal of Materials Research
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• v.13 no.2
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• pp.120-125
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• 2003

A low melting borosilicate glass frit was used as an adhesion promoter, which enables $MnWO_4$to be sintered with in a reasonable sintering temperature range ($800∼1000^{\circ}C$). The glass was evaluated for glass transition temperature ($Τ_{g}$ X) and thermal expansion coefficient($\alpha$). Mechanical property (Vickers hardness), grain growth, the comparison of lattice parameter and pore distribution of sintered $MnWO_4$ with the frit were methodically discussed. As sintering temperature increased, a typical liquid phase sintering showed the rapid grain growth and high densification of X$MnWO_4$grain, improvement of hardness (until $920^{\circ}C$) and different pore size distribution. Resistance of sintered $MnWO_4$varied from 450k$\Omega$ to 8.8M$\Omega$ under the measuring humidify ranging from 30 to 90%. Thus, the results will contribute to the application of glass frit containing sensor materials and their future use.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.97-100
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• 1992

The Degradation mechanism of the ZnO-varistor fabricated with the content of a 3-Composition seed grain is discussed using the method of Thermally Stimulated Current (TSC). The spectra of TSC is measured in the temperature range of -130～270$^{\circ}C$ with a various forming electric fields E$\sub$f/, temperature T$\sub$f/ time tf, and a various rising rate of temperature. It is observed that there are appeared the peaks of ${\alpha}$, ${\alpha}$$_2$, ${\beta}$ and ${\gamma}$from high temperature in a TSC spectrum. It seems that ${\alpha}$$_1$ peak is due to thermal depolarization of donor ions forming the space charge in the depletion layer, and ${\alpha}$$_2$peak is due to the detrapping of trapped electrons in deep trap level of intergranular layer, and ${\beta}$ peak is due to the thermal exciting of carrier existing in the donor level of grain itself, and ${\gamma}$ peak is due to the thermal exciting of trapped carrier in all shallow trap site randomly distributed in the inner of sample and/or a intrinsic impurity existing in it.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.309-314
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• 2004

Static and transient behaviour of Low Temperature Poly-Si TFTs (LTPS-TFTs) and Single Grain TFTs (SG- TFTs) are compared 3-D simulation is applied here for the first time to TFTs to account for the structure and twin boundaries in SG-TFTs.

• Applied Microscopy
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• v.1 no.1
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• pp.3-10
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• 1969

By the use of electron microscope, the study has beek made on the grain size in photo graphic emulsions, which are made at different temperature. It is found that ,the optimum temperature is $60^{\circ}C$, at which the average grain size obtained is the biggest. Also electron micrographs show NaCl-type crystal structure of AgBr and AgCl, as we expected.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.155-160
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• 2005

The objective of this research was to establish a domestically available cooling storage technique by cold-air in winter, using winter cool air ventilation fur determining rough rice cooling method in the storage and dry bin. The rough rice storage characteristics of two test conditions, winter cool-air ventilation storage and ambient temperature storage, were evaluated from January to July 2001, using a storage and dry bin of 300-ton capacity. Results of this research are as follows: Grain temperature was from $-5.1\~-8.5^{\circ}C$ after winter cool-air ventilation, and grain initial temperature for ambient temperature bin storage was $0.3\~1.9^{\circ}C$. Moisture content of rough rice decreased from $0.28\;to\;0.93\%$ and from $1.53\;to\;1.92\%$ to compare with original moisture contents for winter cool-air ventilation, and for ambient temperature bin storage, respectively. Broken ratio of brown rice from winter cool-air ventilation bin increased from $0.16\;to\; 0.92\%$, and brown rice broken ratio was from $2.24\;to\;2.86\%$ for ambient temperature bin storage to compare with initial broken ratio. Hardness of stored rice increased along storage period increase in alt storage methods, and cooling bin storage increased rice hardness of 0.271kgf: this increasing was lower then the other methods from 0.059 to 2.239kgf. Germination rates were decreased approximately 9.03, 3.14 and $3.20\%$ for upper, middle, and bottom of ventilating winter air bin, respectively, and germination rates of 2.70, 3.47 and $4.14\%$ were approximately decreased for upper, middle, and bottom parts of ambient temperature bin storage, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.182-182
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• 2009

The effect of Re-oxidation on the PTCR properties of Sm-doped barium titanate ceramics was investigated by means of impedance spectroscopy. Electrical properties such as resistance vs. temperature, I-V curve were measured and microstructure was observed with SEM photography. Sample was fabricated with thick film process such as tape casting of green sheet, screen printing of electrode pattern, stacking, firing in reduced atmosphere and re-oxidation, etc. As the temperature of re-oxidation increases, resistance jump as a function of temperature enhances but resistance at room temperature increases. These behavior of resistance as a function of temperature, dependent on the re-oxidation condition, is analyzed with Cole-Cole impedance plot and is shown to be related with the degree of oxidation of grain boundary regardless of grain core during re-oxidation process of sample.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.40-46
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• 1985

The effect of calcining temperature ranged from $700^{\circ}C$ to 110$0^{\circ}C$ on sintering characteristics of morphotropic $Pb(Zr_{0.53}Ti_{0.47})O_3 doped with $Nb_2O_5$ has been investigated. The ratio of sintered grain size to calcined grain size decreased as the calcining temperature increased. The hardness as well as the sintered density of the samples reached a maximum at about 90$0^{\circ}C$. The X-ray diffraction pattern of the sintered sample showed both tetragonal and rhombohedral phases. The tetragonal phases intensity increased with the calcining temperature going through a maximum at about 90$0^{\circ}C$ while the rhombohedral phase intensity remained uneffected. The both intensity were about the same at 90$0^{\circ}C$ The dielectric constant of the sintered samples reached a maximum um while the dielectric dissipation factor showed a minimum at the calcining temperature of about 100$0^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.179-182
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• 2000

The dynamic softening behavior of type 430 ferritic stainless steel could be characterized by the hot torsion test in the temperature range of 900-110$0^{\circ}C$ and the strain rate range of 0.05-5/sec. It is found that the continuous dynamic recrystallization (CDRX) was a major dynamic softening mechanism. The effects of process variables strain ($\varepsilon$) stain rate($\varepsilon$)and temperature (T) on CDRX could be individually established from the analysis of flow stress curves and microstructure. The effect of CDRX individually established from the analysis of flow stress curves and microstructure. The effect of CDRX increased with increasing strain rate and decreasing temperature in continuous deformation. The multipass deformation processes were performed with 10 pass deformations. The CDRX effect occurred in multipass deformatioon. The grain refinement could be achieved from multipass deformation The grain refinement increased with increasing strain rate and decreasing temperature. Also the CDRX in multipass deformation was affected by interpass time and pass strain. The total strain was to be found key parameter to occur CDRX.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.1
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• pp.1-9
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• 1998

The objective of this study is to investigate the effect of solution-treatment temperature on the microstructure and damping capacity of a martensitic Fe-7%Ni-0.4%C alloy. The size of lath increased from $0.3{\mu}m$ to $0.55{\mu}m$ with increasing the solution-treatment temperature from 700 to $1100^{\circ}C$. In addition, the size of block, packet, and austenite grain had tendency to increase with increasing solution-treatment temperature. The damping capacity of the Fe-7%Ni-0.4%C martensitic alloy decreased with increasing the solution treatment temperature. The reason is not attributed to the increase in the size of lath, block, packet, and austenite grain, but to the increase in vacancy concentration which hinders dislocation motion.