• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.1
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• pp.89-94
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• 2015

Objectives: The objective of this study was to determine characteristics of workers' exposures to airborne total and hexavalent chromium by job title in electroplating processes. Methods: Total Cr was determined through a modified method based on NIOSH Method 7024. Airborne hexavalent Cr, Cr(VI), was sampled and extracted according to NIOSH Method 7600 and analyzed at 520 nm using an ion chromatograph/visible detector. Results: The geometric mean(GM) of total Cr concentrations from all factories was $11.2{\mu}g/m^3$(GSD=4.9). The GM of Cr(VI) concentrations from all factories was $2.84{\mu}g/m$ (GSD=5.2), and the concentrations among factories were significantly different (p<0.05). The Cr(VI) levels were lower than total Cr levels. Total Cr exposure levels were highest among buffing workers ($21.6{\mu}g/m^3$), but Cr(VI) levels were highest among plating workers($4.15{\mu}g/m^3$). The concentrations of Cr(VI) and total Cr from plating tasks was highly correlated(r=0.91). Conclusions: In the electroplating industry, plating workers were mainly exposed to Cr(VI), but others were not. Oxidation-reduction states of Cr and job titles should be considered in the exposure or risk assessments of chrome electroplating factories.

• Journal of Adhesion and Interface
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• v.18 no.2
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• pp.53-58
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• 2017

In this study, to overcome a complicated shoe adhesion process such as buffing, pre-treatment by primer in the rubber component of the shoe, we studied adhesion and mechanical properties with rubber compound added $MgCl_2$. We determined adhesion properties of $MgCl_2$ content. Especially, the rubber containing $MgCl_2$ exhibited good adhesion properties to water-based adhesion. Since $MgCl_2$ is a water-soluble salt, it was judged that this phenomenon occurred. The results are confirmed by contact angle and surface morphology measurement. In addition, in the case of rubber compound added $MgCl_2$, the crosslinking efficiency was increased and the NBS resistance was increased.

• Journal of Adhesion and Interface
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• v.19 no.2
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• pp.55-59
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• 2018

In this study, to overcome a complicated shoe adhesion process such as buffing, pre-treatment by primer in the rubber component of the shoe, we studied adhesion mechanical properties with rubber compound added water-soluble salt for the purpose of improving the adhesion between midsole and outsole. Acid salts, basic salt and neutral salts were evaluated, rubber containing basic salts showed excellent adhesion to water-based adhesion. Since the basic salt is present as the hydroxy salt, the surface of rubber is hydrophilized. The results are confirmed by contact angle and IR spectroscopy measurement. In addition, in the case of rubber compound added basic salts, NBS abrasion resistance and hardness were increased by increasing crosslink density, but crosslink time was delayed.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.100-100
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• 2009

This paper is concerned with numerical analyses of residual stresses in welds and material's susceptibility to stress corrosion cracking (SCC) for the primary piping system in nuclear power plants: Both the dissimilar metal weld (DMW) for stainless steel to low alloy steel joints and the similar metal weld (SMW) for forged stainless steel to cast stainless steel joints are considered. Thermal elasto-plastic analyses using the finite element method (FEM) are performed to predict residual stresses generated in fabrication welding and its related processes for both the DMW and SMW, including effects of quenching for cast stainless steel piping, machining of the DMW root, and grinding of the SMW root. As a result, the effect of quenching should be included in the evaluation of residual stresses in the SMW for the cast stainless steel piping. It is deemed that residual stresses in both the DMW and SMW would not affect the SCC susceptibility of the welds providing that the welding processes are completed without any weld repair on the inside wall of the joint. However, the grinding process if performed on the safe-end to piping weld, would produce a high level of residual stresses in the inner surface region and thus a stress improvement process (e.g. buffing) should be considered to reduce susceptibilities to SCC.