• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.6
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• pp.249-256
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• 2003

Samples with the nominal composition, Ag-$Bi_{1.84}Pb_{0.34}Sr_{1.91}Ca_{2.03}Cu_{3.06}O_{10+{\delta}}$ high $T_{c}$ superconductors containing Ag as an additive were fabricated by a solid-state reaction method. Samples with Ag of 10 wt%, 30 wt%, and 50 wt% each were sintered at $860^{\circ}C$~$870^{\circ}C$ for 24 hours. The structural characteristics, the microstructures and the critical temperature with respect to the each samples were investigated by XRD, four-prove methode, SEM and EDS respectively. The $T_{c}\;^{zero}$ of the sample with the 50 wt% Ag additive at the surface showed 94 K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.11
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• pp.870-875
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• 2011

The $(Na_{0.52}K_{0.44})(Nb_{0.9}Sb_{0.06})O_3-0.04dLiTaO_3$ (NKNS-LT) ceramics with various $Cu_2O$ concentration were prepared by the conventional solid state reaction method. The $Cu_2O$ content was varied in the range of 0.1~0.4 wt%. The effects of Cu on microstructure, crystallographic phase transition, and piezoelectric properties were investigated. The material with perovskite structure had a tetragonal phase (T1) when $Cu_2O$ concentration was less than 0.3 wt% and it transformed to another tetragonal phase (T2) when the $Cu_2O$ amount was greater than 0.3 wt%. The phase boundary between T1 and T2 phases appeared at around 0.3 wt% of $Cu_2O$ concentration. The piezoelectric properties were shown the maximum values at the composition of the phase boundary. The electro-mechanical coupling factor ($k_p$) was 0.42 and the piezoelectric charge constant ($d_{33}$) was 245 pC/N at the 0.3 wt% of $Cu_2O$ concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.522-531
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• 2003

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{\delta}}$ high- $T_{c}$ superconductors containing MgO as an additive were fabricated by a solid-state reaction method. Samples with MgO of 5~30 wt% each were sintered at 820~86$0^{\circ}C$ for 24 hours. The structural characteristics, critical temperature, grain size and image of mapping with respect to MgO contents were analyzed by XRD(X-Ray Diffraction), SEM(Scanning Electron Microscope) and EDS(Energy dispersive X-ray spectrometer) respectively. As MgO contents increased, intensity of MgO Peaks and ratio of Bi-2212 phase in superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1104-1109
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• 2001

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+}$$\delta$/ high $T_{c}$ superconductors containing As as an additive were fabricated by a solid-state reaction method. Samples with Ag of 10wt%, 30 wt% and 50 wt% each were sintered at 86$0^{\circ}C$~875$^{\circ}C$ for 24 hours. The structural characteristics, critical temperature and grain size with respect to Ag contents were analyzed by XRD(X-ray Diffraction) and SEM(Scanning Electron Microscope), respectively. As Ag contents increased, XRD peaks of g in Bi-2223 phase superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.increased.

• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.530-538
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• 2003

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+}$$\delta$/ (110 K phase) high $T_{C}$ superconductors containing MgO as an additive were fabricated by a solid-state reaction method. Samples with 5~50 wt％ MgO were sintered at 820~86$0^{\circ}C$ for 24 h. The structural characteristics, critical temperature and grain size of the samples with different MgO contents were analyzed by XRD and SEM. As the MgO content increased, the intensity of MgO peaks and ratio of Bi-2212 phase in superconductors were intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.d.creased.d.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.24-34
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• 1998

In this research, effects of the types and amounts of binders and additives on desulfurization and regeneration reactivities of zinc titanate were investigated. Bentonite and kaolinite were used as binders and Mo-based, Ni-based, and Cu-based compounds were used as additives. A thermogravimetric analyzer (TGA) was utilized to investigate reactivities of desulfurization and regeneration for each sorbent. Two-cycle reactions of desulfurization-regeneration were performed in the TGA reactor. Results of XRD analysis showed that all sorbents had the crystalline phases of $Zn_2TiO_2$ and $Zn_2Ti_3O_8$ irrespective of the type and amount of binder and additive. Kaolinite-bound sorbents gave higher surface areas than bentonite-bound ones and the surface areas and pore volumes of sorbents increased with amount of binder increased. It was found that the most suitable temperatures for desulfurization and regeneration were 680$^{\circ}$C and 730$^{\circ}$C, respectively, and the sorbent prepared by the addition of 3 mol% CuO showed the best performance in terms of desulfurization and regeneration. Nio-added sorbents had good regenerability whereas $MoO_3-based$ sorbents showed poor performance. In cycle experiments in a fixed bed reactor 3 mol% CuO-added sorbents showed high reactivity.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.238-243
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• 2001

Mass reduction and physicochemical properties of the produced compost were investigated during composting domestic food wastes without additive. A small composter used in this study had the height of 15 cm from the center of bottom half circle (diameter 24 cm) up to under the lid, the side length of 50 cm and the horizontal lid angle of $50^{\circ}$ and was operated at the heating unit temperature of $85^{\circ}$. It was mixed by the rotating arm for two minutes in every half hour while supplied with air flow at 3 L/min for 10 minutes in every half hour. This condition was found in a preliminary experiment as optimal for keeping the water content of composting material in the optimal range without adding any bulking materials. The domestic food wastes were added into the composter at the rate of 1 kg/day without additives during composting. The results were as follows; during the composting process, water content maintained in the range of $51.0{\sim}53.5%$. Hemicellulose and lignin contents did not show any tendency, but cellulose content decreased. During the composting process, $NH_3-N$ and $NO_2-N$ were not detected due to nitrification. The contents of inorganic compounds did not increase during the composting process. They were in the range of $1.32{\sim}1.71%\;P_2O_5$, $1.29{\sim}1.48%\;CaO$, $0.41{\sim}0.49%\;MgO$, and $0.38{\sim}0.74%\;K_2O$. For 20 days, weight reduction rate was 67.5% in wet basis, and decomposition rate was 48% in dry basis. Concentration of heavy metals (Cu, Cr, Cd, Pb, Zn, Hg, As) was less than the limiting value of the compost. Maturity of the produced compost was 3 grade through reaching maximum temperature of $46{\sim}48^{\circ}C$.