• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.193-195
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• 1994

In this study, the structural, dielectric and piezoelectrical properties of $xPb(Mg_{1/2}W_{1/2})O_3-(1-x)[0.41Pb(Ni_{1/3}Nb_{2/3})O_3-0.36PbTiO_3-0.23P Zr)_3]$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated. The dielectric constant ${\varepsilon_{33}}^{\tau}$ at loon temperature increased up to 3mol% PMW and decreased with further PMW content. The specimen with 1mol% $Pb(Mg_{1/2}W_{1/2})O_3$, which has the ${\varepsilon_{33}}^{\tau}=5509$, kp=59[%] and $d_{33}=758{\times}10^{-12}[C/N]$, exhibits good characteristics.

• Journal of radiological science and technology
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• v.26 no.1
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• pp.45-50
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• 2003

In this work, we characterized the shieldability and lightweight of radiation protective aprons which were consisted of various metal(Pb, Sn, Ni, Ti and Cu) by measuring the x-ray dose transmitted through the filters. The transmitted ratio and lead equivalent of various metal were obtained by linear interpolation and the lead equivalent of double layered filters contained Pb layer was determined. The transmitted ratio of the apron(0.25 mmPb) specified in KS B 0845 was 5.2%. The transmitted ratio of the filters at the thickness of 0.6 mm was decreased in the other of Ni(32.60%), Ti(17.75%), Cu(13.25%) and Sn(3.84%). From the results of experimental evaluation for combined filter of Pb and Sn, it was founded that in the case of the first Sn layer, the lead equivalent was higher than that of the first Pb layer. The lead equivalent corresponding to apron of 0.25 mmPb was obtained in the double layered filters of Sn(0.19 mm) - Pb(0.1 mm) and Pb(0.1 mm) - Sn(0.37 mm). Thus, the Sn-Pb filter had the lower weight about 13% than apron of 0.25 mmPb.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.532-538
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• 2020

Objectives: The study evaluated correlations among monthly PM_2.5, PM₁₀, Cd, Pb concentrations and the number of Asian dust days. Methods: Based on data from 'The annual report on air quality in Korea from 1999 to 2017', concentrations of PM₁₀, PM_2.5, Cd, Pb, and the number of Asian dust days were recalculated to mean, standard deviation, minimum, and maximum. Correlation coefficients were calculated among PM_2.5, PM₁₀, Cd, Pb, and Asian dust days. Results: Asian dust days were correlated only with PM₁₀ among the four factors of PM₁₀, PM_2.5, Cd, and Pb. The four factors of PM₁₀, PM_2.5, Cd, and Pb were very significantly correlated with each other (p<0.01). Their correlation coefficients for PM₁₀ were 0.800 for PM_2.5, 0.823 for Cd, and 0.892 for Pb. PM_2.5 was also correlated strongly with Cd (0.845) and Pb (0.830). Cd had a correlation with Pb of 0.971. The maximums of PM_2.5, PM₁₀, and Pb were shown to exceed the atmospheric environmental standard of Korea, which necessitates national continuous exposure control. Based on exposure data, Asian dust days were thought to be an exposure factor for Cd and Pb. Conclusion: Asian dust might be a factor in Cd and Pb exposure. National exposure controls are required for exposure to PM_2.5, PM₁₀, Cd, and Pb.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.341-344
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• 2004

The superconducting properties of $YBa_2Cu_3O_x$ with different content impurities of PbO and $BaPbO_3$ were studied. When the PbO was used as an additive in $YBa_2Cu_3O_x$, although the melting point could be reduced, the superconductivity became poor. From the XRD pattern of the sintered mixture of $YBa_2Cu_3O_x$ and PbO it was known that there is a reaction between $YBa_2Cu_3O_x$ and PbO, and the product is $BaPbO_3$. In the process of the reaction the superconducting phase of $YBa_2Cu_3O_x$ was decreased and $BaPbO_3$ would be the main phase in the sample. Therefore, $BaPbO_3$ was chosen as the impurity additive for the comparative study. The single phase of $BaPbO_3$ was synthesized by the simple way from both mixtures of $BaCO_3$ and PbO, $BaCO_3$ and $PbO_2$. Different contents of $BaPbO_3$ (10%, 20%, 30%) were added in the $YBa_2Cu_3O_x$. By the Phase analysis in the XRD patterns it was proved that there was no reaction between $YBa_2Cu_3O_x$ and $BaPbO_3$. When $BaPbO_3$ was used as impurity in $YBa_2Cu_3O_x$ the superconductivity was much better than PbO as an impurity additive in $YBa_2Cu_3O_x$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.297-299
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• 1999

Effects of additives on the ceramic and electrical properties of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ceramics in a perovskite type structure were investigated. The dielectric and piezoelectric properties of the base composition were improved markedly through selection of Fe$_2$O$_3$ additives in proper amounts. The composition Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ obtained the dielectric constant ($\varepsilon$$_{r}$=1,425). Also, electromechanical couping factors for planar(k$_{p}$) and piezoelectric constant(d$_{33}$) were obtained 0.50 and 294[pC/N] at the additives 0wt% Fe$_2$O$_3$ respectively. The mechanical quality facor(Q$_{m}$) of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$+Fe$_2$O$_3$(0.3 wt%) is about 510.510.510.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.09a
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• pp.1-26
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• 2004

The implementation of Pb-free solder technology is making good progress in electronic industry. Further understanding on fundamental issues on Pb-free solders/processes is required to reduce reliability risk factors of Pb-free solder joints. Several reliability issues including thermal fatigue, impact reliability, IMC growth, spalling, void formation are reviewed for Pb-free solder joints. Several applications of Pb-free technology are discussed, such as Pb-free, CBGA, CuCGA, flip chips, and wafer bumping by IMS.

• Asian Journal of Turfgrass Science
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• v.12 no.1
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• pp.31-48
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• 1998

In this paper, pollen types of plants and Pb, N, P, K, Ca and Na in pallens of trees were investigated to control the air and soil pollutions. Morphological types of about 500 species of plants were identified to make the best use of paleontology, medicine and pharmacy. There were the positive correlations between Pb, N, P, K,Ca and Na contents in pollens and soils, respectively. A heavy metal, Pb, contained in pollens was not absorbed by rats. This fact should be utilized to purify air and soils polluted by Pb. Key words: Pb, Pollen, Pollution, puripication, Control.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.446-452
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• 2008

This study was conducted to research the biosorption characteristics using algae, Spirulina platensis, for the removal of Pb and Cu ions in wastewater. Both of free algal cell and immobilized algae by Ca-alginate were used as bioadsorbent, and experiment was proceed in batch reactor for Pb and Cu ions removal, respectively. In the biosorption of Pb and Cu ions by free Spirulina platensis cell, the adsorption equilibrium reached within 20 minute. The higher adsorbed amount of Pb and Cu was shown as increasing of initial concentration of Pb and Cu, and pH of solution, respectively, and the optimum pH was 4.5$\sim$5.0. Under the conditions of initial concentration of Pb or Cu are 200 mg/L, the maximum amounts of Pb and Cu adsorbed to the unit weight of Spirulina platensis were 86.43 and 57.02 mg/g, respectively, and these values were 1.94 and 1.48 times higher than those of activated carbon under same conditions, respectively. The biosorption kinetics of Pb and Cu ions by free Spirulina platensis cell fitted very well to the Freundlich and Langmuir isotherm. The maximum amount of Pb or Cu adsorbed to the unit mass of adsorbent by the Langmuir isotherm($q_{max}$) represented as 95.24 and 62.50 mg/g, respectively. The FT-IR results of free Spirulina platensis biomass showed that biomass has different functional groups and these functional groups are able to react with metal ions in aqueous solution. In the biosorption of Pb and Cu ions by Ca-alginate immobilized algae Spirulina platensis, the adsorption equilibrium reached within 40 min. and observed a little diffusion limitation differed from the free algal cell adsorption.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.120-127
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• 2006

The hammer-milled characteristics of waste wood materials such as lumber, plywood, particleboard(PB), MDF and railroad tic were investigated in this study. The physical and mechanical properties of recycled boards according to types of recycled particle and the mixing ratios were also studied. The hammer-milled, waste wood materials had the dimensional distributions suitable for the core layer panicle. Bending strengths of recycled boards (one layer) were shown in order of plywood, PB(laboratory-fabricated with particles used in the PB factory), lumber, tego film-overlaid plywood, MDF, waste railroad tie, PB(factory-made) and LPL-overlaid PB. Cured resin and creosote containing waste wood contributed to dimensional stability of reconstituted boards. Considering the mixing effects between lumber and plywood with recycled PB particle, lumber particle was contributive to bending strength, MOE and internal bond(IB) strength, whereas plywood particle was contributive to dimensional stability. The bending and IB strength of 3 layer boards composing only recycled waste wood particles in core layer of board were in order of lumber, plywood, PB and MDF. On the other hand, the thickness swelling was in order of PB, lumber, plywood and MDF. Bending strength of the 3 layer boards mixed with recycled PB-particle in the core layer had a decreasing tendency, as the mixing ratios of recycled PB-particles increased. The dimensional stability of 3 layer recycled board was improved as the mixing ratio of recycled PB-particle increased same as in one layer. Formaldehyde emission of boards fabricated with recycled PB-particles in the core layer of the PB was in the range of E2 grade (below 5.0mg/l).

• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.647-655
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• 2016

Lead dioxide ($PbO_2$) is an electrode material that is effective for organic pollutant degradation based on hydroxyl radical ($^{\bullet}OH$) attack. Representative parameters for $PbO_2$ electrodeposition are summarized to current, temperature, reaction time, concentration of Pb(II) and electrolyte agent. In this study, $Ti/PbO_2$ electrodes were fabricated by electrodeposition method under controlled reaction time, current density, temperature, concentration of $HNO_3$ electrolyte. Effects of deposition parameters on $^{\bullet}OH$ evolution were investigated in terms of electrochemical bleaching of p-Nitrosodimethylaniline (RNO). As major results, the $^{\bullet}OH$ evolution was promoted at the $PbO_2$ that was deposited in longer reaction time (1-90 min), lower current density ($0.5-50mA/cm^2$), higher temperature ($5-65^{\circ}C$) and lower $HNO_3$ concentration (0.01-1.0 M). Especially, the $PbO_2$ which was deposited in 0.01 M of lowest $HNO_3$ concentration by applying $20mA/cm^2$ for above 10 min was most effective on $^{\bullet}OH$ evolution. The performance gap between $PbO_2$s that was best and worst in $^{\bullet}OH$ evolution was about 41%. Among the properties of $PbO_2$ related on $^{\bullet}OH$ evolution performance, conductivity of $Ti/PbO_2$ significantly influenced on $^{\bullet}OH$ evolution. The increase in conductivity promoted $^{\bullet}OH$ evolution. In addition, the increase in crystal size of $PbO_2$ interfered $^{\bullet}OH$ evolution at surface of some $PbO_2$ deposits.