• Journal of the Korean Ceramic Society
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• v.20 no.4
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• pp.333-339
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• 1983

Semiconducting glaxe of iron system for the recent use as high Voltage porcelain insulators often showed the tendancy of unstable thermal properties. Thus the development of frit including magnetite was studied to cover the defect. In the experimental process melted and quenched frits were ground pelletized and heat-treated at various temperatures in the range of 800-1 $300^{\circ}C$ for various soaking time within 4 hours and then crystallized specimens were obtained. The speciment were studied with optical and electron microscope DTA x-ray diffractometer and electrometer The results obtained were as follows : 1) The optimum condition for the crystal growth of magnetite in the frite was the heat-treatment of $1300^{\circ}C$ for 3hrs and in this case the range of crystal size was $10-11\mu\textrm{m}$ 2) The activation energy for the crystal growth of magnetite was 21.1 kcal/mole. 3) The heat-treament at $1, 250^{\circ}C$ and $1, 300^{\circ}C$ resulted in the good thermal stability and the range of surface resistivity was $3.5{\times}10^4-4.0{\times}10^7$, /TEX> $\Omega$/$cm^2$ which was adguate to semiconducting frit. 4) The conduction mechanism seems to be due to the electron mobility rather than ion mobility and the activa-tion energy for the conduction was 0.07-0.15eV/mole for the heat-treated specimes in the range of 1, 250-1, 300C

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.152-153
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• 2007

$CuInSe_2$ single crystal thin film was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. After the as-grown $CuInSe_2$ single crystal thin films was annealed in Cu-, Se-, and In-atmospheres, the origin of point defects of $CuInSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Cu}$, $V_{Se}$, $Cu_{lnt}$, and $Se_{lnt}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuInSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that In in $CuInSe_2$/GaAs did not form the native defects because In in $CuInSe_2$ single crystal thin films existed in the form of stable bonds.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.161-170
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• 2007

A submerged biofilm sequencing batch reactor (SBSBR) process, which liquor was internally circulated through sandfilter, was designed, and performances in swine wastewater treatment was evaluated under a condition of no external carbon source addition. Denitrification of NOx-N with loading rate in vertical and slope type of sandfilter was 19% and 3.8%, respectively, showing approximately 5 times difference, and so vertical type sandfilter was chosen for the combination with SBSBR. When the process was operated under 15 days HRT, 105L/hr.m3 of internal circulation rate and 54g/m3.d of NH4-N loading rate, treatment efficiencies of STOC, NH4-N and TN (as NH4-N plus NOx-N) was 75%, 97% and 85%, respectively. By conducting internal circulation through sandfilter, removal performances of TN were enhanced by 14%, and the elevation of nitrogen removal was mainly attributed to occurrence of denitrification in sandfilter. Also, approximately 57% of phosphorus was removed with the conduction of internal circulation through sandfilter, meanwhile phosphorus concentration in final effluent rather increased when the internal circulation was not performed. Therefore, It was quite sure that the continuous internal circulation of liquor through sandfilter could contribute to enhancement of biological nutrient removal. Under 60g/m3.d of NH4-N loading rate, the NH4-N level in final effluent was relatively low and constant(below 20mg/L) and over 80% of nitrogen removal was maintained in spite of loading rate increase up to 100g/m3.d. However, the treatment efficiency of nitrogen was deteriorated with further increase of loading rate. Based on this result, an optimum loading rate of nitrogen for the process would be 100g/m3.d.