• Corrosion Science and Technology
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• 제2권1호
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• pp.1-6
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• 2003

A comprehensive coverage of corrosion in batteries is rendered difficult by the wide choice of materials, environments and physical features as obtained in practical settings. Understanding of the complex processes that occur in these electrochemical systems gets clearer as new theoretical approaches backed by sophisticated analytical and characterization techniques continue to provide valuable insights which aid in controlling/mitigating wasteful corrosion reactions which affect battery shelf-life, cycle life, rate capability and capacity. In the light of the above, I limit myself to a discussion on corrosion aspects in representative system such as conventional Leclanche, lead-acid battery and magnesium batteries, and advanced lithium systems.

• Tribology and Lubricants
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• 제32권1호
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• pp.32-37
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• 2016

The wear characteristics of metal ball and seat in a metal-seated ball valve significantly affect the performances such as leakage and valve torque. In this work, the wear characteristics of metal ball and seat are experimentally investigated. A stainless steel ball and seat with a high corrosion-resistant coating are prepared and a component level test was performed. The hardness and surface roughness of specimens cut from the metal ball and seat are measured before and after the test using a micro-Vickers hardness tester and confocal microscopy, respectively. In order to assess the wear characteristics, the surfaces of the specimens are carefully examined after the test. The confocal microscope data show that the surface roughness values of both the ball and seat increase by a factor of 3-4, which may lead to an increase in valve torque. However, the wear of the seat is found to be more significant than that of the ball. In addition, a comparison of the surfaces of the ball and seat before and after testing revealed that adhesive and abrasive wear are the major wear mechanisms. The results of this study may aid in the design of metal-seated ball valves from the tribological point of view.

• 한국산업보건학회지
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• 제8권2호
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• pp.196-208
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• 1998

To improve the quality of environmental measurements and evaluation of the workplace air in the pigment manufacturing industries, we analyzed metal(chromium, cadmium, lead, iron, cobalt, manganese, antimony, titanium, arsenic, and selenium) concentrations by ICP-AES in sixty seven samples of inorganic bulk pigments which are produced and/or used in Korea. We also collected MSDS which has to be supplied by manufacturer and/or supplier and posted in the workplace according to the Hazard Communication Standards, and compared the number of metals listed in each MSDS with the number of metals determined by ICP-AES. Results were as followed; 1. Among seventeen yellowish-colored samples, chromium(2~19%) and lead(0.1~61%) were the two major metals. In thirteen reddish-colored samples, iron was the major component with 37~81%. Cobalt and manganese were detected in blue-colored samples with less than 1%, while antimony and titanium were the major two metals in white-colored pigments with 178~300 ppm and with 36~65%, respectively. 2. In area samples collected in workplace air(one pigments producing factory and five retailer stores), iron and manganese were detected but the concentrations not exceeded the TLVs(1 and $5mg/m^3$, respectively). In three of fifteen samples, the concentrations of lead exceeded the TLV ($0.05mg/m^3$). 3. Two out of seven companies provided MSDS, and the average provision rate was 22.4%. And the coincidence rate of the number of metals referenced in MSDS and determined by ICP-AES mostly accorded, but in one sample, different metal was detected from MSDS. In summary, metals have to be concerned in evaluation of the workplace air dealing with compounds of inorganic pigments dust are cobalt, chromium, iron, manganese, lead and antimony, and these are simultaneously determined by ICP-AES. Taking this opportunity, it is needed to reinforce that the personnel is to be concerned about prevention of workers' ill health regarding to provision of MSDS.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2737-2740
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• 2012

The use of plants to remove toxic metals from soil (phytoremediation) is emerging as a cost-effective alternative to conventional methods for the removal of heavy metals from contaminated soil. Indian mustard (Brassica juncea) was used as the plant to accumulate high tissue concentrations of lead when grown in contaminated soil. For this study, the application of an electric field combined effectively with EDTA-enhanced phytoremediation. A stimulation of direct and alternating electric potential was compared and EDTA-enhanced phytoremediation of lead using Indian mustard has been performed. The effects of experimental parameters such as operating voltage with different concentration of EDTA, the number of graphite electrodes, and cultivation period on the removal of toxic metal were studied. Shoot lead accumulations in Indian mustard increased as the concentration of EDTA and dc electric potential was increased. Two to four folds was increased when EDTA plus a dc electric potential was applied, compared to an ac electric potential. The maximum lead accumulation in the shoots was achieved by applying EDTA plus dc electric potential with 6 graphite electrodes.

• 한국정밀공학회지
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• 제22권2호
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• pp.133-138
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• 2005

The deformation of sheet metal due to the residual stress during blanking or piercing process, is numerically simulated by means of a commercial finite element code. Two dimensional plain strain problem is solved and then its result is applied to the deformation analysis of the lead frame. The plain strain element is applied to the 2D problem to observe the Von Mises equivalent stress concentration at the both shearing edges. As the punch penetrates into the sheet material, the stress concentration generated on both edges is getting increased to be the shearing surface. The limits of the punching depth applied to the simulation is 16% and 24% of the sheet thickness for the plain strain element and the hexahedral element, respectively. The hexahedral element and the limit of punching depth were applied to the deformation analysis of the lead frame for the blanking process. The FEM results for the lead deformation were very good agreement with the experimental ones. This paper shows that the coarse mesh has enabled to analyze the lead deformation generated due to the blanking mechanism. This simple approach to save the calculation time will be very effective to the design of the blanking tools in industries.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.182-189
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• 2018

A neutron generation system was developed to induce fissile fission in a lead slowing down spectrometer (LSDS) system. The source neutron is one of the key factors for LSDS system work. The LSDS was developed to quantify the isotopic contents of fissile materials in spent nuclear fuel and recycled fuel. The source neutron is produced at a multilayered target by the (e,${\gamma}$)(${\gamma}$,n) reaction and slowed down at the lead medium. Activation analysis of the target materials is necessary to estimate the lifetime, durability, and safety of the target system. The CINDER90 code was used for the activation analysis, and it can involve three-dimensional geometry, position dependent neutron flux, and multigroup cross-section libraries. Several sensitivity calculations for a metal target with different geometries, materials, and coolants were done to achieve a high neutron generation rate and a low activation characteristic. Based on the results of the activation analysis, tantalum was chosen as a target material due to its better activation characteristics, and helium gas was suggested as a coolant. In addition, activation in a lead medium was performed. After a distance of 55 cm from the lead surface to the neutron incidence, the neutron intensity dramatically decreased; this result indicates very low activation.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.97-97
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• 2005

• 소성∙가공
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• 제3권2호
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• pp.147-155
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• 1994

The service life of tools in metal forming technology is to a large extent limited by wear and fatigue fracture of the active elements. This presents a basic request for tool cost minimization and reduction of extensive machine down time, caused by premature tool failure. Currents developments are dominated by steps to reduce the causes of tool failure. A main problem of forming technology remains the insufficient reliability of tools due to a large and incalculable life time fluctuation. Only a systematic investigation of the failure mechanisms and operational loading of tools can lead to future improvements in tool layout, that is optimization of tool usage.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1252-1254
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• 2005

Recently, PDP barrier ribs require the formation of complex structure so that they are usually formed by etching method. For producing the fine ribs structure, during the etching process the metal ions of matrix (glass) of barrier materials should be understood on the etching mechanism with etching condition. We analyzed the quantity of Pb, Si, and B ions from the etch solution as a function of etching time.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.317-318
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• 2010

At the latest industry develops, heavy metals or sludge contaminated surrounding farm land and rivers. In this study, wished to solve problem by saying contaminated sludge and tailing and heavy metals to do solidification using Magnesia phosphate cement. Confirmed through above experiment that magnesia is effect in solidification and stabilization of chromium and lead.