• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.335-340
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• 1992

Undoped PbTiO3 ceramics was successfully prepared by using sol-gel process, which had not been fabricated due to its microcracks created by anisotropic stress during phase transition from cubic to tetragonal phase. Fabrication of undoped PbTiO3 ceramics via sol-gel processing was very much affected by the PbO content of the samples as well as PbO vapor from sintering atmosphere. Excess PbO was found to promote rapid grain growth in PbTiO3 ceramics. After sintering at 1100$^{\circ}C$ average grain size of PbTiO3 ceramics with excess PbO was about 8 times greater than that of stoichiometric composition, which may be due to PbO liquid phase from excess PbO.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.841-848
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• 1994

The sintering behavior of La-modified PbTiO3 ceramics was investigated in order to improve the poor sinterability of PbTiO3. Addition of La improved the sinterability. It was confirmed that this improvement was due to the decrease in tetragonality ratio c/a of crystal lattice. The variations of dielectric constant and pyroelectric coefficient were measured with temperature. It was observed that with the increase of La content, Curie temperature decreased and dielectric constant at room temperature increased. La-modified PbTiO3 ceramics had smaller pyroelectric figure of merits than those of pyroelectric materials in use. The effects of grain size on dielectric and pyroelectric properties were also investigated. The change of grain size had effect on maximum dielectric constant and pyroelectric coefficient, but is had little effect on pyroelectric figure of merit at room temperature. The closer examination near ferro-paraelectric phase transition temperature revealed that the behavior of phase transition approached a more relaxor character with the increase of La content and the decrease of grain size.

• Journal of the Korean institute of surface engineering
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• v.22 no.4
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• pp.168-178
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• 1989

The compositions and microstructures of Pb-Sn alloy electrodeposits were investigated in terms of the electrolysis conditions conditions by using fluoborate bath. The Pb content of alloy deposit decreased with increasing dreasing current density until the limting content was obtained. The proferred orientation of Pb-phase in the alloy changed in the sequence of (110)longrightarrow(100)longrightarrow(100)+(110)(311)longrightarrowrandom distribution of crystals with increasing cathode overpotential, while that of $\beta$-Sn phase was (110)(301)(211)n mixed texture. The smooth surface with granular crystallites was obtained below medium current desity, while the rough surface texture was formed at high current density.

• The Korean Journal of Ecology
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• v.15 no.4
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• pp.433-449
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• 1992

Three horticultural herbaceous plants and a natural herbaceous plant were tested to determine the growth responses, biomass and uptake of cadmium(cd), lead(pb) by application of cd and pb soil treatment in pot culture. The ecological effects on the growth of the plants were investigated to determine the tolerance for the heavy metal pollutants cd and pb. the marginal concentrain of cd treatment on the growth of the each plant was below the 1, 000 ppm treatment of cd. The marginal concentration of pb treatment was below the 1, 000ppm treatment of pb in cultivation of salvia splendens ker., celosia cristata l. and below the 3, 000ppm treatment of pb in cultivation of portulaca grandiflora hook., sedum saramentosum bunge. the resistance for cd of sedum saramentosum bunge, celosia criastata l., portulaca grandiflora hook. and salvia splendens ker. was in the listed order. The resistence for pb was in order of sedum saramentosum bunge, portulaca grandiflora hook. Salvia splendens ker.and celosia criastata l.stems. The flowering of portulaca grandiflora hook. was sustained in the pb 1, 000ppm treated group only. The higher the concentration of pb in the soil cultivated the plants was, the less the content of leaf chlorophy11 in each plant was. The number of stomata per unit leaf area was the highest in salvia splendens ker. and in order of celosia l., sedum saramentosum bunge., portulaca grandiflora hook., the higher the cd and pb concentration of cd and pb treatment was, the more the concent of cd and pb in the part of each plant increased. the content of cd and pb in the stems of salvia spiendens ker. was the highest in the 1, 000ppm-treated ground and in order of the roots, the leaves and the flowers.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.17-22
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• 2003

The experimental FT-IR spectra and DTA curves of the $PbO-Bi_2O_3-B_2O_3-SiO_2$ glasses have been investigated. The composition ratio dependence of glass transition temperature showed that the structure of this glass system changes at 60 mol% $Bi_2O_3$. We have observed that the FT-IR spectra of the investigated samples with high bismuth content are dominated by bands associated to the structural units of the heaviest cation, $Bi^{3+}$ and the boron atoms in the treated samples are three and four coordinated even for very high $Bi_2O_3$ content. The low intensity of these non-bridging oxygen bands, for high PbO content glasses, can be attributed to the strong network-forming roles of PbO. The glasses absorption bands exhibited a greater change in intensities on crystallization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.186-189
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• 2003

The role of excess Pb about the crystallization behavior and electrical properties in b(Zr$\sub$0.52/Ti$\sub$0.48/)O3(PZT) thin films has not been precisely defined. In this work, the effect of excess Pb content on the ferroelectric properties of these films was investigated. To analyze the effect, PZT films containing various amounts of excess Pb were Prepared. PZT thin films were deposited on the Pt/Ti bottom electrode by rf magnetron sputtering method and then they were crystallized by rapid thermal annealing (RTA). The experiment showed that all PZT films indicated perovskite polycrystalline structure with preferred orientation (111) and no pyrochlore phase was observed. As higher excess Pb was included, the films showed that value of leakage current shift from 2.03${\times}$10$\^$-6/ to 6.63 ${\times}$ 10$\^$-8/A/cm$^2$ at 100kV/cm, and value of remanent polarization shift from 8.587 ${\mu}$C /cm$^2$ to 4.256 ${\mu}$C/ cm$^2$. Electrical properties of PZT thin film affected by Pb excess content of target were explained to be caused of defect among space charges and defect grain boundaries.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.24-28
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• 2018

To understand the effects of Cd substitution for Cu, $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ (x = 0 ~ 0.5) compounds were synthesized and the structural and superconducting properties of the compounds were characterized. Resistivity data revealed that superconducting transition temperature rises initially up to x = 0.25 and then decreases as the Cd doping content increases. Room-temperature thermoelectric power decreases at first up to x = 0.25 and then increases with higher Cd doping content, indicating that the change in $T_c$ is mainly caused by the change in the hole concentration on the superconducting planes by the Cd doping. The non-monotonic dependence of the lattice parameters and the transition temperature with Cd doping content is discussed in connection with the possible formation of $Pb^{+2}$ ions and the removal of excess oxygen caused by Cd substitution in the charge reservoir layer. A correlation between transition temperature and c/a lattice parameter ratio was observed for the $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ system.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.291-296
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• 1986

A pot experiment was conducted to find out the effects of water management and application of slaked lime and wollastonite on Pb uptake of rice in a Pb added soil. The soil was adjusted to 0, 150, 300 and 600 ppm of Pb concentration. The slake lime was applied at the equivalent amount of lime requirement with 150kg/10a adding and the wollastonite, 200kg/10a, respectively. The results obtained were as follows. 1. The lead contents in leaf stem and brown rice increased with increasing the soil Pb content and the ratio of Pb/(Ca+Mg) equivalent in soil but they showed no influence on yields. 2. The application of lime and wollastonite reduced Pb content in plant. 3. The lead content in plant was higher in intermittently irrigated treatment than in submersed irrigation. 4. The soil pH was increased in the order of lime, wollastonite and control. 5. $1N-NH_4$ OAC soluble Pb content in soil was higher in the submersed irrigation than in the intermittently irrigated and was higher in wollastonite application treatment than the slaked lime after harvesting.

• Korean Journal of Materials Research
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• v.1 no.4
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• pp.221-228
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• 1991

In this study we have investigated the sealing characteristics of glasses suitable for producing the magnetic gap of the ferrite head cores which have been widely used for VTR and computer magnetic heads. $PbO-B_2O_3$ g1asses were evaluated by measuring microhardness, thermal expansion coefficient and sliding wear resistance. Concentration distribution of elements at the interface was observed by WDS. wettability was measured by high temperature microscopy. The results were as follows ; 1. In sealing glasses of $PbO-B_2O_3$ system, thermal expansion coefficient and wear volume were increased with increasing PbO content, and were decreased with increasing $B_2O_3$ content. 2. The contact angle of $PbO-B_2O_3$ Systems was mainly influenced by PbO content. 3. The sealing temperature showed a tendency to decrease proportionally with the increase of the coefficient of thermal expansion. 4. The diffusion at the interface between Mn-Zn single crystal ferrite and sealing glasses of $PbO-B_2O_3$ system was dominated by small amount of diffusion of ferrite content into glass part, which was very little affected by sealing heat treatment time.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.311-317
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• 2004

This study was designed to investigate the effect of Korean traditional tea materials on lead (Pb) accumulation and histological changes in Pb-administered rats. Male rats were divided into six groups: a normal, Pb, and Pb-water extract of Korean traditional tea materials (green tea: GT, persimmon leaf: PL, safflower seed: SS, Eucommia ulmoides: EU) groups. Pb (25 mg/kg BW) was orally administered once a day for 4 weeks. The extract of GT, PL, SS, and EU were administered based on 1.26 g of raw traditional tea materials/kg Bw/day. Pb contents of serum and liver were significantly higher in the Pb group than in the normal group. However the water extracts of GT, PL, SS, and EU administration lowered Pb contents of serum and liver in the Pb-administered rats, respectively. Serum Zn content was significantly higher in the Pb group than in the normal group, whereas, Cu and Fe contents were lower in the Pb group. Hepatic Ca content was significantly lower in the Pb group compared to the normal group. In the present study, water extract of Korean traditional tea materials administration effectively improved Cu and Fe contents of serum and liver. Infiltration of the local inflammation was found in Pb group, whereas water extracts of Korean traditional tea materials administration attenuated histological changes of tissues.