• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.12-15
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• 1986

Lead tolerance of $Pt/Al_2O_3$ catalysts was evaluated for CO oxidation depending on the properties of the alumina supports and base metals added as promoter. Among the four different alumina supports, the support with a large macropore volume (0.45 cc/g) and 5% Ce has shown the best resistence to lead poisoning. Most of the base metals added to the Pt-catalysts were found to be ineffective for improving lead resistence, but boron has shown an excellent lead tolerence, although it decreases the initial catalytic activity.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.399-400
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• 2020

본 논문은 Sensored BLDC 모터의 제어방법을 설명하고, 효율적인 최적 제어를 하기위해 Lead Angle 제어를 하는 방법에 대하여 설명하였다. Lead Angle 값을 실시간 Auto Tuning 하는 기법을 설계 및 구현하였다. 실제 Microchip 사의 DSC를 사용하여 Software로 동작을 구현하였으며, PWM 스위칭 하기 위한 반도체 소자는 IGBT 모듈인 IPM을 사용하여 BLDC 모터의 구동회로인 인버터를 구성하였다. 실제 사용하는 400W급 BLDC 모터를 사용하여 Lead Angle 제어와 Auto Tuning 실험결과를 비교 검증하였다.

• Korean Management Science Review
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• v.13 no.1
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• pp.47-55
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• 1996

Rapid globalization of production and marketing functions makes choice of international transportation mode of great importance. In this paper, transportation mode is characterized by two factors, mean and variability of transportation lead time. We developed a simple mathematical model to estimate the relative impact of mean lead time, lead time variance and demand variance on the required average inventory level under specified service rates.

• Journal of Preventive Medicine and Public Health
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• v.29 no.3 s.54
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• pp.693-700
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• 1996

The purpose of this study was to determine whether workers at a factory next to a lead recycling factory in Pusan, were affected by lead contamination. The mean air lead concentration of lead recycling factory was $0.21mg/m^3(TWA=0.05mg/m^3)$. Thirty-nine male workers of Factory A, Cr. plating factory next to the lead recycling factory were exposed group and a comparison group, 62 male workers of Factory B were selected from another Cr. plating factory about 8.5km away from lead recycling factory. Air lead concentration of each workplace was checked for 4 times from August f to August 20 in 1995 by low volume air sampler. Each subject was interviewed about age, life-style, smoking, work history, and residence etc, and venous blood was drawn for lead measurement by graphite furnace atomic absorption spectrometry. We have observed that air lead concentration and blood lead concentration of Factory A was higher than Factory $B(2.6{\pm}1.6\;Vs.\;1.2{\pm}0.2{\mu}g/m^3,\;14.9{\pm}1.6\;Vs.\;12.2{\pm}1.6{\mu}g/dl)$. We believe that other environmental lead sources such as transportation and residence did not affect air lead and blood lead concentration differences of both factory. We concluded that high air lead and blood lead concentration of Factory A were caused by lead contamination generated by the neighboring lead recycling factory.

• Journal of Preventive Medicine and Public Health
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• v.31 no.3 s.62
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• pp.449-459
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• 1998

This study was started to find out if plasma malondialdehyde(MDA), $\alpha-tocopherol$ and erythrocyte superoxide dismutase(SOD) activity could be markers of biological activity resulting from exposed to lead in workers. Blood samples were randomly obtained from lead-exposed workers(n=29), $CO_2$, welders(n=60) and office workers(n=60). We used whole blood to analyse blood lead with atomic absorption spectrophotometer. Superoxide dismutase activity in erythrocyte was measured with spetrophotometer. MDA and $\alpha-tocopherol$ in plasma were measured with high performance liquid chromatography. Lead-exposed workers was significantly high in blood lead concentration$(29.37{\mu}g/d\ell)$ compared with welders$(6.42{\mu}g/d\ell)$ and office workers$(5.01{\mu}g/d\ell)$. The level of plasma MDA was significantly higher in the lead-exposed workers($1.87{\mu}mol/g$ cholesterol) than the welders($1.41{\mu}mol/g$ cholesterol) and office workers($1.41{\mu}mol/g$ cholesterol). Erythrocyte SOD activity in lead-exposed workers(56.80 U/g Hb) was significantly increased than those of welders(37.63 U/g Hb) and office workers(20.47 U/g Hb). The plasma $\alpha-tocopherol$ level of lead-exposed workers($4.93{\mu}g/g$ cholesterol) was statistically different from welders($4.25{\mu}g/g$ cholesterol) and office workers$4.28{\mu}g/g$ cholesterol). Neither age nor smoking was related to SOD or MDA level. Blood lead was significantly correlated with erythrocyte SOD activity(r=0.405), plasma MDA(r=0.296) and $\alpha-tocopherol$ (r=0.207). Plasma MDA was also significantly correlated with SOD (r=0.217). In multiple regression analysis, the change of MDA and SOD activity level related to the blood lead concentration. These results suggested that the increase of plasma MDA and erythrocyte SOD activity in lead-exposed workers had a close relationship with the oxidative stress induced by lead.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.1
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• pp.88-96
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• 1996

This study was conducted to establish model between lead and ZPP concentration in blood of workers exposed to lead. Workers employed in secondary smelting manufacturing industry showed $85.1{\mu}g/dl$ of blood lead level, exceeding $60{\mu}g/dl$, the Criteria for Removal defined by Occupational Safety and Health Act of Korea. Average blood lead level of workers in the battery manufacturing industry was $51.3{\mu}g/dl$, locating between $40{\mu}g/dl$ and $60{\mu}g/dl$, the Criteria for Requiring Medical Removal. Blood lead level of in the litharge and radiator manufacturing industry was below $40{\mu}g/dl$, the Criteria Requiring Temporary Medical Removal. Blood lead levels of workers by industry were Significantly different(p<0.05). 50(21 %) showed blood lead levels above $60{\mu}g/dl$, the Criteria for Removal and 66(27.7 %) showed blood lead levels between the Criteria for Requiring Medical Removal, $40-60{\mu}g/dl$. Thus, approximately 50 percent of workers indicated blood lead levels above $40{\mu}g/dl$, the Criteria Requiring Temporary Medical Removal and should receive medical examination and consultation including biological monitoring. Average ZPP level of workers employed in the secondary smelting industry was $186.2{\mu}g/dl$, exceeding above $150{\mu}g/dl$, the Criteria for Removal. Seventy seven of all workers(32.3 %) showed ZPP level above $100-150{\mu}g/dl$, the Criteria for Requiring Medical Removal. The most appropriate model for predicting ZPP in blood was log-linear regression model. Log linear regression models between lead and ZPP concentrations in blood was Log ZPP(${\mu}g/dl$) = -0.2340 + 1.2270 Log Pb-B(${\mu}g/dl$)(standard error of estimate: 0,089, ${\gamma}^2=0.4456$, n=238, P=0.0001), Blood-in-lead explained 44.56 % of the variance in log(ZPP in blood).

• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.119-125
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• 2002

Application of phytoremediation in the polluted area to remove undesirable materials is a complex and difficult subject without detailed investigation and experimentation. We investigated the accumulation patterns of cadmium and lead in plants naturally grown, the bioavailability of plants to accumulate these toxic metals and the responses of P. thunbergii to cadmium and lead. The soil samples contained detectable lead (<17.5$\mu\textrm{g}$/g), whereas cadmium was not detected in the soils of study area. The whole body of Persicaria thunbergii contained detectable lead (<320.8$\mu\textrm{g}$/g) but cadmium was detected only in the stem (<7.4$\mu\textrm{g}$/g) and root (<10.4$\mu\textrm{g}$/g) of P. thunbergii. Cadmium was not detected in Trapa japonica and Nymphoides peltata, whereas lead was detected in T. japonica (<323.7$\mu\textrm{g}$/g) and N. peltata (<177.5$\mu\textrm{g}$/g). Correlation coefficient between lead content in soil and in these plant samples represented positive correlation. The total content of lead in each plant sample increased in the order of N.peltata$\leq$P.thunbergii

• The Korean Journal of Ecology
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• v.25 no.4
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• pp.253-259
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• 2002

Application of phytoremediation in the polluted area to remove undesirable materials is a complex and difficult subject without detailed investigation and experimentation. We investigated the accumulation patterns of cadmium and lead in plants naturally grown, the bioavailability of plants to accumulate these toxic metals and the responses of P. thunbergii to cadmium and lead. The soil samples contained detectable lead (＜$17.5_\mu$g/g), whereas cadmium was not detected in the soils of study area. The whole body of Persicaria thunbergii contained detectable lead (＜320.$8_\mu$g/g/g) but cadmium was detected only in the stem (＜7.$4_\mu$g/g/g) and root (＜10.$4_\mu$g/g/g) of P. thunbergii. Cadmium was not detected in Trapa japonica and Nymphoides peltata, whereas lead was detected in T. japonica (＜323.$7_\mu$g/g/g) and N. peltata (＜177.$5_\mu$g/g/g). Correlation coefficient between lead content in soil and in these plant samples represented positive correlation. The total content of lead in each plant sample increased in the order of N. peltata$\leq$P. thunbergii

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.09a
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• pp.93-99
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• 2004

At present, LG Electronics pushes ahead to eliminate the Pb(Lead) -a hazardous material- from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C-+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• Structural Engineering and Mechanics
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• v.48 no.6
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• pp.809-822
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• 2013

Base isolation is widely used in seismic resisting buildings due to its low construction cost, high reliability, mature theory and convenient usage. However, it is difficult to design the isolation layer in high-rise buildings using the available bearings because high-rise buildings are characterized with long period, low horizontal stiffness, and complex re-distribution of the internal forces under earthquake loads etc. In this paper, a simple and innovative isolation bearing, named Teflon-based lead rubber isolation bearing, is developed to address the mentioned problems. The Teflon-based lead rubber isolation bearing consists of friction material and lead rubber isolation bearing. Hence, it integrates advantages of friction bearings and lead rubber isolation bearings so that improves the stability of base isolation system. An experimental study was conducted to validate the effectiveness of this new bearing. The effects of vertical loading, displacement amplitude and loading frequency on the force-displacement relationship and energy dissipation capacity of the Teflon-based lead rubber isolation bearing were studied. An analytical model was also proposed to predict the force-displacement relationship of the new bearing. Comparison of analytical and experimental results showed that the analytical model can accurately predict the force-displacement relationship and elastic shear deflection of the Teflon-based lead rubber isolation bearings.