• 한국재료학회지
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• 제23권5호
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• pp.276-280
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• 2013

Coal tar is the primary feedstock of premium graphitizable carbon precursor. Coal tars are residues formed as byproducts of thermal treatments of coal. Coal tar pitches were prepared through two different heat treatment schedules and their properties were characterized. One was prepared with argon and oxidation treatment with oxygen; the other was prepared with oxygen treatment at low temperature and then argon treatment at high temperature; both used coal tar to prepare coal tar pitches. To modulate the properties, different heat treatment temperatures ($300{\sim}400^{\circ}C$) were used for the coal tar pitches. The prepared coal tar pitches were investigated to determine several properties, such as softening point, C/H ratio, coke yield, and aromaticity index. The coal tar pitches were subject to considerable changes in chemical composition that arose due to polymerization after heat treatment. Coal tar pitch showed considerable increases in softening point, C/H ratio, coke yields, and aromaticity index compared to those characteristics for coal tar. The contents of gamma resin, which consists of low molecular weight compounds in the pitches and is insoluble in toluene, showed that the degree of polymerization in the pitches was proportional to C/H ratio. Using an oxidizing atmosphere like air to prepare the pitches from coal tar was an effective way to increase the aromaticity index at relatively low temperature.

• 한국환경성돌연변이발암원학회지
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• 제20권1호
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• pp.34-39
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• 2000

Although shipbuilding workers were exposed to a variety of genotoxic compounds including polycyclic aromatic hydrocarbons (PAHs), limited number of studies were conducted to evaluate the biomarkers related to PAH exposure in painting workers in shipbuilding industry. One hundred and thirty three workers including 73 employees using coal tar paints were recruited from a shipbuilding company located in South Korea. Urinary 1-hydroxypyrene glucuronide (1-OHPG), as internal dose of PAH exposure, were measured by synchronous fluorescence spectroscopy after immunoaffinity purification using monoclonal antibody 8E11. Glutathione S-transferase (GST)M1 and GSTT1 genotypes were assessed by multiplex PCR. Information on demographic characteristics, smoking gabit, diet, job title, use of personal protective equipments were collected by self-administered questionnaire. Urinary 1-OHPG were higher in workers using coal tar paints than in workers using general paints, however, the difference was not statistically significant (p=0.20, Mann-Whitney U test). Urinary 1-OHPG levels in smokers were higher than in non-smokers (p<0.05 by Mann-Whitney U test) and there was a significant increase in urinary 1-OHPG levels with the numbers of cigarettes consumed per day (Spearman's correlation coefficient = 0.28, p=0.02). Genetic polymorphisms of GSTM1 and GSTT1 did not influence the level of 1-OHPG in study subjects. Multiple regression analysis show that smoking is the only significant predictor for lon-transformed 1-OHPG (overall model R2=0.1). These results suggest that workers using coal tar paints were exposed to significant amount of PAHs and individual difference in xenobiotic metabolism might affect the levels of internal dose of PAHs.

• 공업화학
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• 제32권5호
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• pp.569-573
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• 2021

본 연구에서는 코크스, 바인더 피치 및 함침 피치를 사용하여 고밀도 탄소 블록을 제조하고, 함침 공정 시 피치의 유동성이 탄소 블록의 고밀도화에 미치는 영향을 고찰하였다. 코크스와 바인더 피치의 고압 성형을 통해 그린블록을 제조하고 열처리 공정을 통하여 탄소 블록을 얻었다. 열처리 공정 시 바인더 피치의 휘발에 의해 생성된 기공을 제거하고자 함침 공정을 진행하였다. 함침 공정은 함침 피치를 용융하는 전처리 단계와 피치를 탄소 블록에 함침하는 고압 반응 단계로 나누어 진행하였다. 함침 피치의 용융은 140~200 ℃에서 진행하였으며, 열처리 온도가 증가할수록 함침 피치의 점도가 감소하였다. 함침 피치의 점도 감소는 유동성을 향상시켜 탄소 블록 내부 기공을 효율적으로 함침하여 탄소 블록의 기공률을 83% 감소시켰고 겉보기 밀도를 5% 상승시켰다.