• Journal of Environmental Science International
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• v.12 no.12
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• pp.1269-1276
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• 2003

In order to know the effect of atuoclaving on the heavy metal removal using chitosan, lead removal capacities and removal rates by various chitosans in aqueous solution were compared according to the various autoclaving time. The lead removal efficiencies and removal rates by the autoclaved chitosan were found to be on the order of 15 min(98％) ＞ 10 min(95％) ＞ 30 min(83％) ＞ 5 min(53％) ＞ 60 min(47％) ＞ 0 min(22％) chitosan. The molecular weight of chitosan was decreased by the increase of autoclaving time. Therefore, the heavy metal removal capacity was not well correlated to the molecular weight. Langmuir isotherm was well fitted to experimental results of equilibrium adsorption on chitosan. In order to examine the process of lead removal by the autoclaved chitosan, TEMs, SEMs and FT-IR analyses were used. The surface of autoclaved chitosan was much more porous and the lead removal was mainly occurred on the surface of chitosan. The structure of autoclaved chitosan was same as that of controlled chitosan.

• Journal of Nutrition and Health
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• v.17 no.3
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• pp.193-198
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• 1984

Rice, the staple food in Korea, is deficient to some extent in protein, lipid and vitamins. This study was carried out in order to investigate the effects of dietary supplementation to the rice diet of cellulose, ginseng, and ${\alpha}$-tocopherol on lead toxicity in rats. Using male rats fed the rice diet with the distilled drinking water containing 750mg of lead as nitrate per liter, for 11 weeks, organ weights, hemoglobin levels, serum glutamic pyruvic transaminase activity and accumulation of lead in liver, blood and kidney were observed. Supplementation of cellulose, ginseng and ${\alpha}$-tocopherol to the lead groups showed the protective effect significantly in the weight of liver but no influence in hemoglobin levels. Ginseng especially decreased the serum glutamic pyruvic transaminase activity to normal level. The three supplemented diets reduced the lead accumulation in kidney and blood, but not in liver.

• IE interfaces
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• v.12 no.3
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• pp.414-423
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• 1999

A nuclear power plant requires a huge amount of initial investment and long construction lead time. As we expect that there may exist a relationship between investment and construction lead time, a number of researchers have reported that nearly a half of investments is incurred due to time factors such as the time value of money and inflation or escalation rates. Therefore, we investigated in this paper a relationship between the initial investment and the construction lead time of a nuclear power plant construction, and proposed a method for a trade-off analysis between the annual equivalent worth and the investment alternatives to reduce the construction lead time. Finally, we presented a real case to numerically explain the steps of the method presented in this paper.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.77-80
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• 2001

IC lead frame needs the precision shape for good efficiency. In the blanking process, there are many parameter effected the dimensional accuracy : lead width, blanking order, striper force, tool clearance etc. In this research, the4 undesirable defects appeared in the final blanking process. so we measured the deflection of lead according to the stripper force using $PAM-STAMP_{TM}$. In the result, the deflection was decreased by increasing the stripper force properly. and we changed the blanking order on the test model. In the blanking order, deflection is good from the outer line position blanking to center line position. so we can design the precision die without tryout by the prediction of the lead deflection.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.49-55
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• 2002

For making a lead terminal(condenser, resistor etc.), it is the matter that lead wire have to be supplied smooth without twisting and curving when it is supplied to the further processing (cutting, forming, attach process) after it being forwarded. The purpose of this study is to solve the winding claims of lead wire through the structural expansion of winding equipment to which the improvement of packing equipment to forward safely and supply the lead wire and QFD method are applied. The results of this study is available to solve the technical problem caused by the installation of the existing flyer system for the prevention of twisting and can expect the quality assurance as it prevents the claim(surface fault) caused by the bumping among lead wire which are involved in the packing equipment in its moving stage.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.389-395
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• 2006

The use of pine bark, a natural adsorbent prepared from Korean Red Pine (Pinus densifloral), was studied for its adsorption behavior of lead ion from aqueous solution. Adsorption experiments were carried out on lead ion concentrations of 10mg/L. Adsorption of lead ion could be described by both Langmuir and Freundlich adsorption isotherms. Treatment of the bark with nitric acid greatly increased initial adsorption rate, and equilibrium sorption capacity increased by approximately 48%. A pseudo second-order kinetic model fitted well for the kinetic behavior of lead ion adsorption onto the bark. Acid-treated bark demonstrated its adsorption capacity quite close to that of granular activated carbon. Results of this study indicated that ion exchange and chelation were involved in the adsorption process.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.98-103
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• 1998

A study on the removal of mercury and lead by microorganisms, Saccharomyces cerevisiae and Aureobasidium pullulans, was performed, in which the comparison of adsorption model between these two heavy metals was done. The amounts of mercury removed were more than those of lead in both microorganisms. In case of mercury, the adsorption isotherm of S. cerevisiae was accorded with Langmuir model but A. pullulans was followed to Freundlich model. In the case of lead, however, the adsorption isotherm had opposite results. The adsorption rate of mercury to S. cerevisiae was faster than that of A. pullulans, but in the case of lead, it revealed contrary results. It seems, therefore, that the type of microorganisms used as biosorbents should be selected differently with the type of heavy metals removed for applying these to real adsorption process.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.113-117
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• 2003

To reduce the doming of the shadow mask due to thermal expansion and to prevent the color discrepancy, the electron reflecting layer with lead tungsten oxides on the electron gun side of shadow mask was formed by screen printing method and doming property was evaluated in CRT. First, the lead tungsten oxides were prepared by calcining the mixture of lead oxide and tungsten oxide above 600$^{\circ}C$. Second, the paste which has the anti-doming composition including the lead tungsten oxides was coated by screen-printing method. As a result, the doming of the shadow mask was reduced about from 30 to 45%.

• Biomedical Science Letters
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• v.12 no.4
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• pp.371-374
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• 2006

This study was carried out to investigate the relationship of the cadmium and lead levels in blood by age, gender and smoking status among 181 students in Gyeongnam province from June 2005 to July 2006. The cadmium and lead levels in blood was analyzed by atomic absorption spectrophotometer. Subjects were classified for the investigation according to smoking status as smokers and nonsmokers, age and gender. Mean blood cadmium level in male and female was $1.65{\mu}g/dl,\;1.10{\mu}g/dl$ respectively. Male was significantly higher than that of female. Blood cadmium levels in heavy smokers ($11{\sim}20\;ea/day$) and light smokers ($1{\sim}10\;ea/day$) were $2.34{\mu}g/dl,\;1.10{\mu}g/dl$ respectively. Heavy smokers were significantly higher than those of light smokers. In the comparison of age, gender and smoking status in blood Lead levels were no significant differences. In conclusion, heavy smoking was the most significant risk factor to increase blood cadmium levels. The further study will need analysis of the other factors related to the elevation of the cadmium and lead levels.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.131-136
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• 2001

In this paper, a high-temperature superconductor(HTS) current lead operating in current sharing mode is described. The minimum heat dissipation and the optimum safety factor(cross-sectional area) is obtained analytically for partial current sharing HTS leads. It is assumed that the current lead is in conduction cooled state, and the sheath material is the alloy of silver and gold. The reduced cross-sectional area results partial current sharing state, and consequently reduces conduction heat transfer, but the Joule heat generation is increased. The optimized HTS current lead is different from the conventional copper leads. In the copper leads, the minimum heat dissipation is obtained for the zero gradient of temperature at warm end. However, the temperature gradient at warm end is not zero when the HTS lead operates at minimum dissipation state.