• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.219-224
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• 2021

Ion flotation is an efficient method to remove metal ions from aqueous solution. In this work, ion flotation was applied to calcium removal from aqueous solution. The parameters used included sodium stearate (SS) and sodium dodecyl sulfate (SDS) as collectors, 1-butanol and 1-propanol as frothers, pH, and air-flow rate. An L16 orthogonal array was chosen according to the mentioned factors and levels, and experimental tests were conducted according to the Taguchi orthogonal array. The results showed that all of the factors except one had significant effect on the flotation performance. The percentage contribution of parameters showed that type of frother and type of collector made the greatest (43.14%) and the lowest (9.86%) contribution, respectively. In optimal conditions, the recovery of Ca (II) ion was 45.67%. Also, the results illustrated that the Taguchi method could predict calcium removal from aqueous solution by ion flotation with 2.63%. This study showed that the use of ion flotation was an effective method for Ca (II) ion removal from aqueous solution.

• Research in Community and Public Health Nursing
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• v.13 no.4
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• pp.817-825
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• 2002

Purpose: This study was carried out to investigate the prevalence and the main factors influencing the farmer's Syndrome in farmers in Korea. Method: A survey questionnaire was completed by 238 farmers who lived in 8 agricultural districts in Seosan City. The data were collected from April 10 to May 5, 2002. Results: The prevalence of the farmer's Syndrome was 42.6%, and its prevalence rate in woman was higher than that in man. The prevalence of the farmers syndrome proportionally increased with advanced age. Variables that were positively correlated with the farmer's syndrome were age, duration of farming, days of resting, and the number of the agricultural chemical's poisoning. On the other hand, variables that were negatively correlated with the farmers syndrome were smoking, sleeping hours, economic condition, and level of educational. In a regression analysis, the factors influencing the farmers syndrome were age, sex, sleeping hours, days of resting, and the number of the agricultural chemical's poisoning, which accounted for 25% of the total variance. Conclusion: Based on these study results, older age and woman gender are the remarkable risk factors influencing the farmer's syndrome. Sleeping hours, days of resting, and the number of the agricultural chemical's poisoning were also the significant attributable variables to the farmers syndrome.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1283-1287
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• 2004

The design rules are being more strict with requirement of operation speed and development of IC industry. For this reason, required minimum line-width has been narrowed under sub-micron region. As the length of minimum line-width is narrowed, local and global planarization are being prominent. CMP(Chemical-Mechanical Polishing), one of the planarizarion technology, is a process which polishes with the ascent of chemical reaction and relative velocity between pad and wafer without surface defects. CMP is performed with a complex interaction among many factors, how CMP has an interaction with such factors is not evident. Accordingly, the studies on this are still carrying out. Therefore, an examination of the CMP phenomena and an accurate understanding of compositive factors are urgently needed. In this paper, we will consider of the relations between the effects of temperature which influences many factors having an effect on polishing results and the characteristics of CMP in order to understand and estimate the influence of temperature. Then, through the interaction of shown temperature and polishing result, we could expect to boost fundamental understanding on complex CMP phenomena.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1351-1353
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• 2003

• Bulletin of the Korean Chemical Society
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• v.18 no.5
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• pp.471-473
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• 1997

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.2
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• pp.26-33
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• 2009

A new testing method to evaluate the deposition potential of white pitch was developed. The new method involves depositing the potential white pitch particles on the air bubble covered plastic film in the pitch deposit tester (PDT) developed by KRICT and analysing the deposited area of white pitch using an image analyzer. In addition, the effect of two important factors (pH and calcium hardness) on white pitch deposition potential was elucidated. When pH of the coated broke stock was increased from neutral to alkali or the calcium hardness of the stock was decreased, the pitch deposit area was decreased, implying that these two factors have to be controlled during the evaluation of pitch deposition potential. It was found that hydrophobicity of the surface of latex binding films repulped is a key factor influencing white pitch deposition.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.187-187
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• 2011

Nowadays, the issue of solar cell durability in local weather and environment is a crucial issue. Above all, surface corrosion on solar cell multilayers is a major factor that determines the durability of commercial solar cells; corrosive chemical interactions between air, humidity and chemical species and solar cell multilayers can unfavorably affect the durability. Here, we study microscopic and spectroscopic surface techniques to investigate the corrosive interaction on the antireflective layers of solar cell multilayers under various conditions such as acid, base, constant temperature and humidity. Surface morphology and adhesion force were characterized with atomic force microscopy before and after chemical treatment. Chemical composition, and transmittance factors were studied with X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy, respectively. Based on these studies, we suggest the dominant factors in the corrosive chemical processes, and their influences on the structural, compositional, and optical properties of the antireflective layers.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.323-327
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• 2008

A focused library of pyrazole-based compounds was constructed towards novel transcription factor inhibitors. Complementary hydrogen bonding interaction with b-sheet peptide structures was the basis for the design of 5-amino-3-pyrazole carboxamide scaffold. From the preliminary inhibition assay against several transcription factors, compounds 7e and 8g were identified as novel lead compounds against HIF-1a and NF-AT transcription factors, respectively.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.257-261
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• 1970

Some factors such as the weight ratio, reaction time and temperature for the separation of rare earth elements from monazite are studied. The influence of the inorganic phosphate for the leaching is also studied.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.703-706
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• 1997

Response surface method was applied to the predicting optimum conditions of benzene synthesis for radiocarbon dating. The weight of carbon dioxide, the temperature of lithium container for producing acetylene and the activation temperature of catalyst which was used for the cyclization of acetylene to benzene were used as experimental factors. The yields of benzene synthesis were measured from twelve experiments which were carried out under various experimental conditions. The polynomial equation was obtained by using three experimental factors and yields. The validity of polynomial equation was confirmed by comparing the calculated yields with the experimental ones.