• Magazine of RCR
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• v.3 no.1
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• pp.10-19
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• 2007

• Economic and Environmental Geology
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• v.49 no.2
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• pp.77-88
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• 2016

Chrysotile is a 1:1 sheet silicate mineral belonging to serpentine group. It has been highlighted studies because of uses, shapes and structural characteristics of the fibrous chrysotile. However, it was designated as Class 1 carcinogen, so high attentions were being placed on detoxification studies of chrysotile. The objectives of this study were to investigate changes of mineralogical characteristics of chrysotile and to suggest detoxification mechanism of chrysotile by thermal decomposition. Samples for this study were obtained from LAB Chrysotile mine in Canada. The samples were heated in air in the range of 600 to $1,300^{\circ}C$. Changes of mineralogical characteristics such as crystal structure, shape, and chemical composition of the chrysotile fibers were examined by TG-DTA, XRD, FT-IR, TEM-EDS and SEM-EDS analyses. As a result of thermal decomposition, the fibrous chrysotile having hollow tube structure was dehydroxylated at $600-650^{\circ}C$ and transformed to disordered chrysotile by removal of OH at the octahedral sheet (MgOH) (Dehydroxylation 1). Upon increasing temperature, it was transformed to forsterite ($Mg_2SiO_4$) at $820^{\circ}C$ by rearrangement of Mg, Si and O (Dehydroxylation 2). In addition, crystal structure of forsterite had begun to transform at $800^{\circ}C$, and gradually grown 3-dimensionally to enstatite ($MgSiO_3$) by recrystallization after the heating above $1,100^{\circ}C$. And then finally transformed to spherical minerals. This study showed chrysotile structure was collapsed about $600-700^{\circ}C$ by dehydroxylation. And then the fibrous chrysotile was transformed to forsterite and enstatite, as non-hazardous minerals. Therefore, this study indicates heat treatment can be used to detoxification of chrysotile.

• Analytical Science and Technology
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• v.27 no.3
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• pp.153-160
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• 2014

While variety of cases of studies about asbestos analysis methods are released internationally, the results of Asbestos Containing Materials (ACM) according to differences in the method of the analysis is becoming an issue. In this study, homogeneity ensured ACM samples were analyzed by visual estimation method and point counting method, and the result cound be used not only to improve the reliability on asbestos analysis of the institutions and analysts but also to obtain the basic data of Polarizing Light Microscope (PLM) analysis by comparing and evaluating. Asbestos analysis were divided into qualitative and quantitative analysis method. The quantitative analysis was performed by visual estimation method and point counting method (total 400 points) of EPA 600-R-93-116 method by using PLM. Firstly, The following was the result of homogeneity of the samples by ANOVA (Analysis of variance) and the results were satisfied. The results of qualitative analysis showed that the samples were chrysotile and amosite, and about the results of quantitative analysis, asbestos concentration determined by point counting method tend to be lower than concentrations determined by visual estimation method and also, pont counting method was a little more complicated and time-consuming.

• Journal of Life Science
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• v.16 no.1
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• pp.58-63
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• 2006

There was cross-sectional study on investigating the factors related asbestos-related disease on chest radiograph of workers exposed to asbestos in ship repair. According to Occupational Safety & Health Administration asbestos standard, medical surveillance, chest radiologic study, pulmonary function test and medical questionnaire are performed in 118 subjects exposed to asbestos for 10 years or more in ship repair. The sixteen out of 118 subjects $(13.6\%)$ were observed asbestos-related disease finding on chest radiography. Significant factors related to those finding on chest radiography were abnormal pulmonary function test, cough, sputum, past history of respiratory disease, work duration. Workers with Significant factors related asbestos-related disease finding on chest radiography should be managed on a strict program. Further, factors unrelated with asbestos-related disease finding on this study should be evaluated prospectively for medical surveillance program of workers exposed to asbestos.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.223-228
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• 2021

The final disposal method for asbestos building materials is to be landfilled at a designated waste landfill in accordance with the Waste Management Act. However, it is difficult to secure a domestic designated waste landfill site to landfill the entire amount of asbestos waste, which is expected to emit more than 400,000 ton/year by 2044. In this study, a detoxification treatment was performed on a ceiling tex with a density of 1.0 to 1.2g/cm³ containing 3 to 7% of chrysotile, and it was used as a reinforcing fiber for extruded panels. It was confirmed that asbestos components were detoxified through the reaction process using 30% oxalic acid and carbon dioxide, and it was recognized that these detoxifying properties were maintained even after extrusion molding. However, it was found that milling to a fiber size of less than 1mm for complete detoxification of asbestos resulted in a decrease in reinforcing performance. Therefore, in the case of using detoxified asbestos fibers in the extrusion molding process, it is considered desirable to add fibers with a length of 5mm or more to improve the reinforcing performance.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.613-623
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• 2013

This study is purposed to evaluate the airborne asbestos concentrations in life environment surroundings in Seoul. In study, we investigated airborne asbestos concentrations in thirteen subway stations, four monitoring networks and each vicinity roadside, six stream surroundings, four tunnels quarterly and we also investigated relationship between the airborne asbestos concentrations and ambient temperature in monitoring networks and time-based airborne asbestos concentration variability for two typical monitoring networks, two subway stations transferred and used by lots of people through Phase Contrast Microscopy (PCM) and Transmission Electron Microscopy (TEM). The airborne asbestos concentrations by PCM for 4 objects of study were less than the detection limit (7 fiber/$mm^2$) in 111 (50%) out of 223 samples. The highest concentration was 0.0130 f/cc. But additional TEM analysis result for samples exceeding the guideline value for indoor air quality (0.01 f/cc) proposed by the Ministry of Environment (Korea), no asbestos was detected. Similarly TEM analysis result for 124 samples, no asbestos was detected. The average airborne asbestos concentrations by PCM in subway stations, monitoring networks, streams and tunnels were $0.0041{\pm}0.0027$ f/cc, $0.0015{\pm}0.0011$ f/cc, $0.0024{\pm}0.0012$ f/cc and $0.0016{\pm}0.0020$ f/cc. All objects of study were satisfied with the guideline value for indoor air quality. The relationship between the airborne asbestos concentrations and ambient temperature in monitoring networks was generally positive correlation (r = 0.660). The higher ambient temperature was and the more transient population was, the airborne asbestos concentrations by time for two subway stations were increased. While the airborne asbestos concentrations for two monitoring networks showed no variation pattern according to time.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.407-417
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• 2020

The capacity of the designated landfill site for asbestos-containing waste is approaching its limit because the amount of asbestos-containing slate is increasing every year. There is a need for a method that can safely and inexpensively treat asbestos-containing slate in large capacity and at the same time recycle it. A cement kiln can be an alternative for heat treatment of asbestos-containing slate. We intend to develop a pilot scale device that can simulate the high temperature environment of a cement kiln using a high temperature plasma reactor in this study. In addition, this reactor can be used to inactivate asbestos in the slate and to synthesize one of the minerals of cement, to confirm the possibility of recycling as a cement raw material. The high-temperature plasma reactor as a pilot scale experimental apparatus was manufactured by downsizing to 1/50 the size of an actual cement kiln. The experimental conditions for the deactivation test of the asbestos-containing slate are the same as the firing time of the cement kiln, increasing the temperature to 200-2,000℃ at 100℃ intervals for 20 minutes. XRD, PLM, and TEM-EDS analyses were used to characterize mineralogical characteristics of the slate before and after treatment. It was confirmed that chrysotile [Mg3Si2O5(OH)4] and calcite (CaCO3) in the slate was transformed into forsterite (Mg2SiO4) and calcium silicate (Ca2SiO4), a cement constituent mineral, at 1,500℃ or higher. Therefore, this study may be suggested the economically and safely inactivating large capacity asbestos-containing slate using a cement kiln and the inactivated slate via heat treatment can be recycled as a cement raw material.

• 월간낙농육우
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• v.34 no.12
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• pp.109-113
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• 2014

강원도 홍천강의 수원지인 서석면의 물 맑고 공기 좋은 마을에 자리 잡은 어른목장(강원도 홍천군 서석면 어론리)은 매일 깨끗하게 목장을 청소하고 주변을 정리하는 장인학 이순이 부부의 일터이자 생활공간이다. 계절마다 이름 모를 야생화가 피어나고 한가로이 젖소가 쉬고 있는 모습을 보기 위해 유치원 아이들도 찾는다는 어론 목장을 찾아가 보았다.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.171-183
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• 2010

• 월간산업보건
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• no.7 s.243
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• pp.83-84
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• 2008