• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.2
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• pp.127-138
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• 2009

Rock wool, a kind of asbestos substitutes, was analyzed for its physicochemical properties. After fivers of rock wool were instilled into rat lungs, These pathological changes were evaluated. In addition, the fibers in the lungs were counted and characterized after the lungs were treated for electron microscopical analysis. The lungs of rats showed pathological lesions such as granulomatous changes, but these lesions disappeared at 28 days groups after instilled rats. The rock wool fibers in the lungs decreased more 50 % after 28 days instilled into rat lungs. And rock wool showed early change in fiber compositions after 3 days compare with chrysotile showed after 7 days instilled into rat lungs. This study showed that the durability of rock wool in the lungs is more milder than chrysotile.

• Particle and aerosol research
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• v.9 no.4
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• pp.231-238
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• 2013

Carbon nanotubes (CNTs) are one of the nanomaterials that were discovered by Iijima in 1991 for the first time. CNTs have long cylindrical and axi-symmetric structures. CNTs are made by rolling graphene sheets. Because of their large length-to-diameter ratio, they are called nanotubes. CNTs are categorized as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) based on the shell structures. CNTs are broadly used in various fields, such as scanning probe microscopy, ultra fine nano balance and medicine, due to their extraordinary thermal conductivity, electrical and mechanical properties. Because long, straight CNTs have the same shape as asbestos, which cause cancer in cells lining the lung, there have been many studies on the effects of MWCNTs on human health that have been conducted. Stable atomization of CNTs is very important for the estimation of inhalation toxicity. In the present study, electro-static assisted axial atomizer (EAAA), which is the instrument that uses MWCNTs and aerosolizes them by transforming the single fiber shape using ultrasonic dispersion and electric field, was invented. EAAA consists of a ultrasonic bath for dispersion of MWCNTs and a particle generator for atomizing single fibers. The performance evaluation was conducted in order to assess the possibilities of 6-hour straight atomization with stability, which is the suggested exposure time in a day for the estimation of inhalation toxicity.

• Tuberculosis and Respiratory Diseases
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• v.48 no.2
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• pp.260-267
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• 2000

Giant cell interstitial pneumonia. a synonym for hard metal pneumoconiosis, is a unique form of pulmonary fibrosis resulting from an exposure to hard metal dust. A case of biopsy-proved giant cell interstitial pneumonia in the absence of appropriate history of exposure to hard metal dust is reported. The patient presented with clinical features of chronic interstitial lung disease or idiopathic pulmonary fibrosis. He worked in a chemical laboratory at a fertilizer plant, where he had been exposed to various chemicals such as benzene and toluene. He denied having any other hobby in his house or job at work, which may have exposed him hard metal dust. High-resolution CT scan revealed multi-lobar distribution of ground glass opacity with peripheral and basal lung predominance. The retrieved fluid of bronchoalveolar lavage contained asbestos fiber and showed neutrotphil predominance. Surgical lung biopsy was performed for a definite diagnosis. Lung specimen showed alveolar infiltration of numerous multinucleated giant cells with mild interstitial fibrosis. Upon detailed examination of the lung tissue, one asbestos body was found. An analysis for mineral contents in lung tissue was performed. Compared with the control specimen, the amount of cobalt and several hard metal components in the lung tissue of this patient was ten times higher. We speculated that the inconsistency between occupational history and the findings of pathologic and mineralogical analyses could be explained by the difference in individual immunologic reactivity to hard metal dust despite the relatively small amount of unrecognized environmental exposure(ED: It's hard to understand what this phrase is trying to say).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3177-3183
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• 2013

This paper deals with the robust design of the non-asbestos FCM(Fiber-elastomer Coated Metal) gasket. In order to this, the measurement of the shear stress based on the design of experimet using the orthogonal table was carried out and the control factors for shear stress using the larger-the-better SN ratios with the Taguchi method were evaluated. In addition, the analysis of variance for SN ratios was conducted. The temperature, pressure, duration time and humidity were selected as the control factors. The orthogonal table $L_9(3^4)$ was made of 3 levels for each factor and the measurement of shear stress was acomplished on the base of the table. Delta statistics of time is the highest value 0.93 and therefore the time affect the largest effect on the shear stress of gasket. Also from the analysis, the shear stress shows maximun at the duration time 80 sec, temperature $200^{\circ}C$, pressure 90 $kgf/cm^2$, humidity 60 %RH. P values of duration time and temperature as a results of the analysis of variance are 0.037 and 0.098. Therefore the analysis has significant each with 95% and 90% confidence level.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.1
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• pp.63-69
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• 2010

This study was conducted to compare the concentration of various air contaminants in nine different laboratories during routine activities. Volatile organic compounds (VOC) were sampled and analyzed using NIOSH Method 1500 and asbestos fibers were sampled and analyzed using NIOSH Method 9002 and 7400. Detectable levels of acetone, toluene and ethanol were found in all the laboratories and xylene and n-hexane were detected in eight of the nine laboratories. All the VOC concentrations were well below the Korean Ministry of Labor's Exposure Limit and American Conference of Governmental Industrial Hygienists' (ACGIH) Threshold Limit Values (TLVs). Total VOC concentrations at the university laboratories were significantly higher than those at governmental agency laboratories. Airborne fiber concentrations were below 0.01 fibers/cc, while the concentration of chrysotile was 2% in insulation materials sprayed on the ceiling of one laboratory. While all the governmental agency laboratories (n=4) had fume hoods, two out of the five university laboratories did not have fume hoods. The capture velocity of half of the fume hoods were below the maintenance standard(0.4 m/sec). In conclusion, the study suggests that the current controls in place at both university and government agency laboratories are not sufficient in limiting exposure to harmful chemicals to non-detectable levels, though they appear to be adequate in protecting workers to levels below applicable occupational exposure limits. The study also suggests that researchers working in university laboratories may be exposed to greater levels of contaminant than those working in government agency laboratories.