• Journal of Environmental Science International
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• v.19 no.4
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• pp.527-532
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• 2010

Exposure to lead, particularly at chronic low-dose levels, is still a major public health concern. The present study is aimed to evaluate the blood lead levels in populations resident in some abandoned mine areas of Chungbuk, Korea. Eight hundreds and sixty-six subjects who reside in abandoned mine area located in Chungbuk, Korea, were enrolled this study. We evaluated the blood lead level according to the age, gender, and working history in mines. For statistical analysis, SPSS ver 12.0 was used. The geometric mean blood lead levels was $2.93\;{\mu}g/{\ell}$ and nobody showed levels over the guidelines of WHO. Ex-smokers and current-smokers showed significantly higher blood lead levels compared to that of non-smokers. The blood lead levels in individuals with a history of working in a mine was higher than those in individuals without such histories. The populations resident in some Chungbuk abadoned mine area showed low levels of lead in blood. This suggest that lead poisoning might not be induced by abandoned mine in Chungbuk, Korea.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.20-26
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• 2009

In this paper, the switching mode conversion type pulse charger by fly-back converter method for lead battery of the solar cell generator equipment is proposed. And we propose the control circuit and design method of insulated switching mode convert type pulse charger by fly-back convert method in the lead battery. The proposed system can minimize the current consumption by digital pulse. Also the proposed system can generate the constant 10[KHz] frequency, transmit the signal with main control system in the power control system. And it supervises the state of lead battery using one chip micro processor. The proposed the switching mode conversion type pulse charger by the fly-back converter method can charge fast and stabilize lead battery with nominal value 12[V], 20[AH]. Also we propose the design procedure of the power control circuit for turn ratio of fly-back inductor and determining method of values such as the charging current, bulk current, partial current, over current value and fixed charging voltage. The experiment results for the voltage and current wave for partial, bulk, over and fixed charging period show the good charging effect and performance. And the PCB and internal coupling diagram of the switching mode conversion type pulse charger by fly-back converter method is presented.

• Journal of Preventive Medicine and Public Health
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• v.28 no.2 s.50
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• pp.398-405
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• 1995

We experienced a case of occupational lead poisoning employed in a secondary lead smelting plant for 12 years. The patient was 39-year-old male and had been felt dizziness, recent memory impairment and intermittent severe abdominal pain for 2 years. On admission, blood lead level was $92.9{\mu}g/dl$, urinary lead level was $19.9{\mu}g/l$ and zinc protoporphyrin level was $226.0{\mu}g/dl$. On the blood test, hemoglobin was 10.6g/dl and showed normocytic normochromic anemia. There were no abnormal findings in the biochemical and hormonal tests. Decrease of I.Q. and use of words in speaking were found in the psychiatric and psychologic examinations. We observed the finding of motor polyneuropathy in the nerve conduction velocity test. Computed tomographic finding showed calcification lesions in the basal ganglia, dentate nuclei, caudate nuclei, and especially characteristic multiple calcifications were located in the subcortical white matter.

• Environmental Engineering Research
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• v.25 no.4
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• pp.605-613
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• 2020

This study is to investigate the possibility of using activated carbon prepared from Iraqi date-pits (ADP) which are produced from palm trees (Phoenix dactylifera L.) as low-cost reactive material in the permeable reactive barrier (PRB) for treating lead (Pb⁺²) from the contaminated groundwater, and then compare the results experimentally with other common reactive materials such as commercial activated carbon (CAC), zeolite pellets (ZP). Factors influencing sorption such as contact time, initial pH of the solution, sorbent dosage, agitation speed, and initial lead concentration has been studied. Two isotherm models were used for the description of sorption data (Langmuir and Freundlich). The maximum lead sorption capacities were measured for ADP, CAC, and ZP and were found to be 24.5, 12.125, and 4.45 mg/g, respectively. The kinetic data were analyzed using various kinetic models particularly pseudo-first-order, pseudo-second-order, and intraparticle diffusion. COMSOL Multiphysics 3.5a depend on finite element procedure was applied to formulate transmit of lead (Pb⁺²) in the two-dimensional numerical (2D) model under an equilibrium condition. The numerical solution shows that the contaminant plume is hindered by PRB.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.86-95
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• 2017

Active search for lead-free piezoceramics over the last decade has harvested a considerable amount of achievements both in theory and in practice. Few would deny that those achievements are highly beneficial, but agree that this quest of developing the lead-free piezoceramics in replace for PZTs is successfully completed. Nevertheless, few would clearly state where this quest should be directed in our next move. A source of this uncertainty may originate from the fact that it is still not clear how good is good enough to beat PZTs. In this short review, we analyzed the existing literature data to clearly locate the current state of the art of lead-free piezoceramics in comparison to PZT-based piezoceramics. Four strategies of a potential importance were suggested and discussed to help researchers plan and design their future research on lead-free piezoceramics with a recently reported exemplary work.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.462-469
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• 2018

The background spectrum of a $3^{{\prime}{\prime}}{\times}3^{{\prime}{\prime}}$ NaI(Tl) well-type scintillation SILENA detector was measured without shielding, in 6 cm thick lead shielding, and with 2 mm thick electrolytic copper covering the detector inside the lead shielding. The relative remaining background of the lead shield lined with copper was found to be ideal for low-level environmental radioactive spectroscopy. The background total count rate in the (20-2160 KeV) was reduced 28.7 times by the lead and 29 times by the Cu + Pb shielding. The effective reduction of background (1.04) by the copper mainly appeared in the energy range from X-ray up to 500 KeV, while for the total energy range the ratio is 1.01 relative to the lead only. In addition, a strong relation between the full-energy peak absolute efficiency and the detector well height was found using gamma-ray isotropic radiation point sources placed inside the detector well. The full-energy peak efficiency at a midpoint of the well (at 2.5 cm) is three times greater than that on the detector surface. The energy calibrations and the resolution of any single energy line are independent of the locations of the gamma source inside or outside of the well.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.860-866
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• 2019

The lead element or its salts are good radiation shielding materials. However, their toxic effects are high. Due to less toxicity of bismuth salts, the radiation shielding properties of the bismuth salts have been investigated and compared to that of lead salts to establish them as a better alternative to radiation shielding material to the lead element or its salts. The transmission geometry was utilized to measure the mass attenuation coefficient (${\mu}/{\rho}$) of different salts containing lead and bismuth using a high-resolution HPGe detector and different energies (between 81 and 1333 keV) emitted from point sources of $^{133}Ba$, $^{57}Co$, $^{22}Na$, $^{54}Mn$, $^{137}Cs$, and $^{60}Co$. The experimental ${\mu}/{\rho}$ results are compared with the theoretical values obtained through WinXCOM program. The theoretical calculations are in good agreement with their experimental ones. The radiation protection efficiencies, mean free paths, effective atomic numbers and electron densities for the present compounds were determined. The bismuth fluoride ($BiF_3$) is found to have maximum radiation protection efficiency among the selected salts. The results showed that present salts are more effective for reducing the intensity of gamma photons at low energy region.

• Korean Journal of Veterinary Research
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• v.28 no.1
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• pp.179-185
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• 1988

Present study was undertaken in order to evaluate the lead contents of various feedstuffs produced in Korea and the effect of the burning of gasoline by automobiles on the lead contents. Ninety-one samples near and 95 far road were collected from 9 regions(Do). All of the samples were washed, dry-ashed and analyzed for lead content using atomic absorption spectrophotometer. The mean values obtained were checked for significance of difference using computer. The results obtained were summerized as follows: 1. The lead content in ${\mu}g/g$ of agriculture-byproducts were measured with the following mean values and ranges(in parentheses). Rice bran: $2.07{\pm}1.67$ (0-5.00), rice hull $1.84{\pm}1.18$ (0-3.71), rice straw, $1.27{\pm}1.09$ (0-3.62), soybean pod:$4.55{\pm}3.13$ ($1.13{\pm}10.43$), and wheat bran: $1.69{\pm}0.86$ (0-3.65). 2. The lead content in ${\mu}g/g$ of pasture plants were measured with the following mean values and ranges. Kudzu:$2.71{\pm}1.74$ ($0.38{\pm}8.75$), leed: $2.03{\pm}1.61$ (0-4.54), lespedeza:$4.73{\pm}5.93$ (0-31.25), sagebrush: $4.08{\pm}3.75$ (0-12.18), Korean-grass: $2.11{\pm}1.38$ (0-5.50), maizestalk: $2.62{\pm}2.35$ (0-8.65), clover: $3.83{\pm}2.97$ (0-12.19), alfalfa: $7.14{\pm}0.97$ (4.46-9.25), and timothy: $5.86{\pm}4.79$ (0-9.25). 3. Fourteen samples (22.2%) out of 63 agriculture-byproduct samples and 42 (34.2%) out of 123 pasture plant samples showed lead content of more than $3{\mu}g/g$ which are said to be the upper limit value for cattle. 4. No significant difference between the mean lead contents of near road, and those of far road was recorgnized. 5. The regional mean values for all kinds of samples collected in Kyungbuk and Kyungnam were significantly (p<0.05, p<0.10) higher compared to those in Chungnam and Jejudo.6. From these results it may be concluded that the burning of gasoline by automobiler did not affect on the lead contentes of washed feedstuffs produced in Korea at present.

• Journal of Korean Institute of Industrial Engineers
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• v.8 no.1
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• pp.3-12
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• 1982

Three types of repair-ordering polices for the production facility with r-out-of-n configuration are considered. Policies are characterized by states of the system and two types of lead times ; regular lead time and expedited lead time. Optimum repair-ordering policy is determined by minimizing the cost rate for the system. Optimum policy consists of the type of policies and repair-ordering time. Variations of the optimum policies are observed with respect to variations of lead times and associated ordering costs and downtime cost, respectively.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.75-79
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• 2008

To control the lead storage batteries it is necessary to consider the characteristics of each battery connected in series. In this study, the charging and discharging characteristics of sealed lead storage batteries 12V/1.2A was investigated one by one through experiments. The results of the experiment shows that one should consider the state of each battery to prevent overcharge or deep discharge. Also, we designed an equipment to measure battery voltages simultaneously using micro-controller. This equipment will be useful for monitoring batteries at PV generation system.