• 한국세라믹학회지
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• 제29권5호
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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.

• 한국세라믹학회지
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• 제31권8호
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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.

• 한국표면공학회지
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• 제22권4호
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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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• 제15권4호
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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.

• 한국안광학회지
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• 제8권1호
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• pp.17-22
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• 2003

$PbO-Bi_2O_3-B_2O_3-SiO_2$ 유리계의 DTA 곡선과 FT-IR 스펙트럼을 조사하였다. 유리전이 온도의 조성비 의존성은 60 mol% $Bi_2O_3$에서 유리계의 구조가 변화하는 것으로 나타났다. 높은 비스무스 함량을 가지는 시료의 FT-IR 스펙트럼 조사에서 무거운 양이온 $Bi^{3+}$의 단위구조와 관계되는 결합이 우세했으며 그리고 고함량의 $Bi_2O_3$ 시료에서도 역시 붕소원자의 3배위와 4배위 진동이 있었다. PbO함량이 높은 유리계의 경우, 비가교 산소밴드의 낮은 강도는 PbO의 망목형성제 역할에 기인 한 것으로 생각된다. 유리의 흡수대는 결정화상태에서 강도가 매우 큰 변화를 보였다.

• 한국전기전자재료학회논문지
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• 제16권3호
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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.

• 한국초전도ㆍ저온공학회논문지
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• 제20권2호
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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.

• 한국토양비료학회지
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• 제19권4호
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• pp.291-296
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• 1986

수도(水稻)에서 납(pb) 흡수양상(吸收樣相) 및 흡수경감효과(吸收輕減效果)를 구명(究明)하기 위(爲)하여 토양(土壤)에 납을 0, 150, 300, 600 ppm 으로 처리(處理)하고 소석회(消石灰) 및 규회석(硅灰石)을 시용(施用)하여 pot 재배(栽培)하고 수도(水稻)의 경엽(莖葉), 현미중(玄米中) 납함량(含量) 및 흡수량(吸收量)과 pH, 칼슘, 마그네슘함량(含量)과의 관계(關係)를 조사(調査)한 결과(結果)는 다음과 같다. 1. 토양중(土壤中) 납처리농도(處理濃度)가 증가(增加)할수록 경엽(莖葉)과 현미중(玄米中) 납함량(含量) 및 흡수량(吸收量)이 증가(增加)하였으나 수량(收量)은 별영향(別影響)이 없었다. 2. 석회물질시용(石灰物質施用)으로 수도(水稻)의 납흡수억제효과(吸收抑制效果)가 인정(認定)되었다. 3. 물관리(管理)에서 수도(水稻)의 납흡수억제효과(吸收抑制效果)는 간단관수구(間斷灌水區)가 상시담수구(常時湛水區)보다 좋았다. 4. 토양중(土壤中) pb/Ca+Mg당량비(當量比)가 증가(增加)할수록 식물체중(植物體中) 납함량(含量)이 증가(增加)하였다. 5. 석회물질시용(石灰物質施用)에 따른 토양(土壤)의 pH는 소석회(消石灰)>규회석(硅灰石)>무시용(無施用)의 순(順)이었다. 6. 시험후(試驗後) 토양중(土壤中) $1N-NH_4$ OAC 가용성(可溶性) 납함량(含量)은 상시담수구(常時湛水區)가 간단관수구(間斷灌水區)보다 높았고 석회물질별(石灰物質別)로는 무시용(無施用)>규회석(硅灰石)>소석회(消石灰)의 순(順)이었다.

• 한국재료학회지
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• 제1권4호
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• pp.221-228
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• 1991

본 연구는 computerdisk drive와 VTR head에 사용되어 지고 있는 ferrite head cores의 gap 형성에 적합한 유리의 봉착특성에 관하여 고찰하였다. 유리의 특성측정은 열팽창 계수, 미세경도, 내마모성을 측정하였으며 계면에서의 원소 농도분포는 WDS에 의해 관찰하였고 젖음성은 고온 현미경으로 측정하였다. 그 결과는 다음과 같다. 1. $PbO-B_2O_3$계 봉착용 유리에 있어서 PbO의 함량이 증가함에 따라 열팽창계수와 마모량이 증가하였으며 $B_2O_3$함량이 증가함에 따라서는 열팽창계수와 마모량이 감소하였다. 2. $PbO-B_2O_3$계 유리에 있어서 contact angle은 PbO함량에 주로 영향을 받는다. 3. 열팽창계수의 증가에 따라 봉착온도는 비례적으로 낮아지는 경향을 나타내었다. 4. Mn-Zn single crystal ferrite와 $PbO-B_2O_3$계 봉착용유리의 융착 계면에서의 확산은 ferrite성분이 glass측으로 소량확산이 이루어졌으며 봉착 열처리 시간에 따라서는 거의 영향을 받지 않았다.

• 한국식품영양과학회지
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• 제33권2호
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• pp.311-317
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• 2004

전통음료의 소재로 애용되는 녹차, 감잎 홍화 및 두충의 열수추출물이 납투여된 흰쥐의 체내 무기질 함량 및 간과 신장조직의 형태학적 변화에 미치는 영향을 구명하기 위하여 체중kg당25mg의 납을 매주 1회 경구투여하였다. 녹차잎, 감잎, 홍화씨 및 두충수피의 열수추출물은 매일 일정시간에 체중 kg당 1.26 g수준이 되도록 4주간 경구투여하였다. 전통음료 소재의 열수추출물 급여시 납투여로 인한 혈청과 간조직의 납축적 억제와 혈청 중의 철과 구리 함량 증가에 효과적인 것을 관찰할 수 있었다. 납투여시 혈청 중 포도당과 알부민 함량은 유의적으로 감소되었으며 크레아티닌과 빌리루빈 할량은 유의 적으로 증가되었다. 반면, 실험식이 급여시 이들 혈청 중 성분함량의 회복을 보였다. 또한 간조직 및 신장조직의 형태학적 변화는 납단독투여군에서 괴사성 소견 및 염증세포의 출현이 관찰되었으나 전통음료 소재의 열수추출물 급여시 조직학적 변화를 완화시키는 것으로 나타났다.