• Journal of the Korean GEO-environmental Society
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• v.3 no.4
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• pp.5-10
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• 2002

Pistia stratiotes(Water Lettuce) can be applied to remove inorganic pollutants from the wastewater for the advanced treatment. This study attempts to remove heavy metals from the secondary treated wastewater. Three different initial concentrations of heavy metals were applied as 0.5, 1.0 and 1.5 mg/L for Lead(Pb) and Chromium(Cr(VI)). In addition, the removal efficiency for the mixture of Lead and Chromium was also observed. The removal efficiency of Pb was in the range of 41.0~72.0% for Pb and it was in the range of 25.0~30.0% for Cr(VI) by Pistia stratiotes. The plants placed in static systems were able to remove the heavy metals in a few days of exposure. However, it was observed that the heavy metals affected produce phytotoxic effects on plants resulting in inhibition of chlorophyl synthesis, decrease in biomass production, and finally plant necrosis. The removal efficiencies of Pb and Cr(VI) by Pistia stratiotes were increased with plant growth.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.755-760
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• 2021

In this study, the shielding rate of major X-ray protective equipment used in the medical environment was calculated using X-ray spectrum data emitted from the diagnostic X-ray generator of The Institute of Physics and Engineering(IPEM) Report-78, and the applicability of radiation protection was investigated. Radiation shielding rates were calculated through reduction rates of air-kerma and total intensity for lead apron (0.3 mmPb), thyroid shield (0.5 mmPb), lead goggles (0.5 mmPb), and lead glass (1.8, 2.7, 3.3 mmPb) used for diagnostic X-ray protection. As a result, the shielding rate calculated as the air kerma reduction rate ranged from 96.31 to 100% at 80 kV, and 90.35 to 100% at 120 kV. In addition, the results of this calculation were well matched with the results of previous studies measuring the actual shielding rate, and it is expected that the X-ray spectrum data of IPEM Report-78 can be used for radiation protection.

• Resources Recycling
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• v.21 no.5
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• pp.65-71
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• 2012

The equilibrium distribution of bismuth and lead between molten PbO-$SiO_2$ slag and bismuth phase was studied in the temperature range of $775^{\circ}C$ to $850^{\circ}C$ in a MgO crucible. The oxygen partial pressure of atmosphere was controlled by $P_{CO2}/P_{CO}$ ratio. The value of $(%PbO)_{slag}/[%Pb]_{metal}$ increased with increasing $SiO_2$ content of slag, and the value of $(%Bi_2O_3)_{slag}/[%Bi]_{metal}$ decreased with increasing $SiO_2$ content of slag. The concentration of Pb in metal increased with increasing temperature. These experimental results agreed well with the thermodynamic prediction.

• Journal of the Korean Society of Radiology
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• v.2 no.3
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• pp.19-25
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• 2008

Commercial analog x-ray detectors based on film cassettes have been showing problems such as with image storage and image transmission. Recently direct conversion material, photoconductor whit flat panel have been researched which generate the electron hole-pair (EHP). In this paper, we researched the electrical properties of the PbO and Lead(II) oxide PbO. film which fabricated by Particle-In-Binder(PIB) method. We compared tetragonal ${\alpha}$-PbO with orthorhombic ${\beta}$-PbO physical property. Tetragonal material was more than orthorhombic material in other paper. The solution was Poly Vinyl Butyral(PVB) in the PIB. We discussed about the sample of x-ray sensitivity, leakage current, Signal to Noise Rate and investigated SEM for the physical property of sample. We need to think more research ${\alpha}$-PbO material fabrication.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.3
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• pp.1-8
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• 2002

In order to study electric properties of (Pb$\_$0.9/La$\_$0.1/)Ti$\_$0.975/O$_3$(PLT (10)) films with varying excess lead concentration (7.5, 10, 12.5, 15 ㏖% excess lead), the PLT films were deposited by sol-gel process. DTA analyses reveal that the crystallization temperature of the precursor powers decreased with increasing amount of excess lead. XRD patterns of PLT reveal pure perovskite structure and the preferred orientation increased with increasing Pb content in the films. With increasing amount of excess P$\_$b/, the relative permittivity ($\xi$$\_$r/) increased and leakage current density at 100 ㎸/cm transformed 4.01$\times$10$\^$-5/, 2.42$\times$10$\^$-6/, 1.27$\times$10$\^$-6/, 1.56$\times$10$\^$-6/A/㎠ respectively. In the results of hysteresis loops measured at 166 kV/cm, the remanent polarization (P$\_$r/) and the coercive field (E$\_$c) are 6.36$\mu$C/cm and 58.7 ㎸/cm, respectively (at 12.5 ㏖% excess P$\_$b/) With increasing amount of excess Pb, the remanent polarization for PLT thin film degraded to about 44%, 27%, 15%, 16% of the initial value after 10$\^$9/ cycles./TEX>) With increasing amount of excess Pb, the remanent polarization for PLT thin film degraded to about 44%, 27%, 15%, 16% of the initial value after $10^{9}$ cycles.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.429-435
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• 2021

In intracavitary radiotherapy, incorrect location of the source can cause excessive dose to normal tissue, so it is essential to evaluate the location accuracy of the source. In this study, basic research was performed on digital line dosimeter based on lead (II) oxide (PbO) to improve analog verification method. Therefore, a polycrystalline PbO unit cell dosimeter was manufactured and the measurement performance for Ir-192 sources was evaluated. As a result, the reproducibility satisfies the evaluation criteria of 1.5% with a relative standard deviation of 0.85%. Linearity showed excellent results with a linear coefficient of R² of 0.9998. In the case of distance dependence evaluation, the power function R² showed 0.9855 for PbO and 0.9974 for diode, and the overall average difference was 1.66% for PbO and 2.18% for diode. This study presents the basic detection performance of the polycrystalline PbO dosimeter for the Ir-192 source and can provide basic data in the field of radiation measurement.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.409-417
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• 2010

Present study aimed to investigate morphological and physiological change in the tissues of Carassius auratus after exposure against Pb (lead) with various rearing condition. We measured the level of accumulated heavy metal and analyzed ultrastructure with transmission electron microscopy. The heavy metal, Pb, was accumulated in the gill, bone and integument increased drastically for exposure periods, the 40 days. The accumulation of Pb in the gill showed relatively higher than that in other tissues. And accumulated Pb amounts also were increased with exposure time dependent manner in the gill, bone and integument tissues. Also, specific activities of antioxidation enzymes in all tissue after exposure to Pb were increased in the course of exposure. And the activities of SOD from tissues exposed to Pb were increased 2 folds than those from the unexposed but GPX activities were maintained constant. The increased numbers of mucous cells in gill tissues exposed to Pb were determined and morphological changes, such as clubbing and fusion, were shown secondary lamella. Also, exposure of Pb for 40 days on gills tissues cause membrane damage in mitochondria and nucleus. In kidney tissues, the atrophied glomerulus was observed, and the empty space in Bowman's capsule was expanded. Based on the all results, it is suggested that the exposure to the high level of Pb for long period affect on the morphology of tissues, and change the enzymatic balance in C. auratus.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.47-53
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• 1983

A strain of Alcaligenes sp. Isolated from the sludge of industrial area was found to uptake 24.1 mg lead/g dried cell during incubation in medium containing 100g/ml of lead. Analyses of cellular subfractions reveal that fractions of cell wall contain 88.6 percent of lead found associated with the cells and the remainder is found associated with the cytoplasmic fraction. Ultrastructural examination of the cells cultured in media containing 500 and 1000g/ml of lead showed no major irregularities between cells of the treated and untreated cultures.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.538-542
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• 2007

Polymeric electrodes for lead ion based on N,N'-bis-thiophen-2-ylmethylene-pyridine-2,6-diamine as an ion carrier were prepared. The membrane electrode (m-3) containing o-NPOE as a plasticizer and 50 mol% additive of ionophore gives an excellent Nernstian response (29.59 mV/decade) and the limit of detection of ?log a (M) = 5.74 to Pb2+ in Pb(NO3)2 solution at room temperature. The prepared electrode provided good sensitivity and outstanding selectivity and response for Pb2+ over a wide variety of other metal ions in pH 7.0 buffer solutions. The good sensitivity and selectivity towards lead ion are attributed to the strong complexation of lead ion to N,N'-bis-thiophen-2-ylmethylene-pyridine-2,6-diamine which has geometrically the proper cavity to coordinate to the ligand.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.51-56
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• 2005

A PVC membrane electrode for lead ion based on 1-phenyl-2-(2-quinolyl)-1,2-dioxo-2-(4-bromo) phenylhydrazone (PQDBP) as ionophore was demonstrated. The optimum composition of the membrane was 30 wt% poly(vinyl chloride), 60 wt% dibutyl phthalate as a plasticizer, 4 wt% ionophore and 6 wt% sodium tetraphenylborate as additive. The electrode exhibits a Nernstian response (28.7 mV decade$^{-1}$) for Pb$^{2+}$ over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1 ${\times}$ 10$^{-6}$ M) with a detection limit of 6.0 ${\times}$ 10$^{-7}$ M. This sensor has a short response time and can be used for at least 2 months without any divergence in potentials. The proposed electrode could be used in a pH range of 3.0-6.0 and revealed good selectivities for Pb$^{+2}$ over a wide variety of other metal ions. It was successfully applied as an indicator electrode for the potentiometric titration of lead ion with potassium chromate and for the direct determination of lead in mine.