• Journal of the Korean Chemical Society
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• v.50 no.2
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• pp.141-152
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• 2006

In this study computer assisted instruction materials for the ‘Solution' chapter in high school chemistry II textbook were developed based on a view of particle and analyze the effect of the materials on 10th and 11th high school students. The contents of developed materials are dissolution, vapor pressure, the change of boiling point and freezing point, osmosis, and so on which are the major contents of Solution chapter in high school chemistry II textbook. Materials were developed with using animation and simulation for students understanding of the phenomena with a particle view point. Many phenomena in a solution were not simplified by colligative property of solution, but tried to explain by the concept of attraction between solute and solvent molecules. This computer assisted learning materials were developed using Flash 5.0 and Flash 6.0 Action Script. Educational effects of the materials on 10th and 11th grade students represented statistically meaningful increase of concept understanding. Especially the materials were effective to the transition stage or formal stage students in 10th grade and formal stage or the natural science major students in 11th grade.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.238-245
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• 2014

Objectives: It was known that workers in synthetic leather company are mainly co-exposed to dimethylformamide(DMF) with methyl ethyl ketone(MEK) or toluene(TOL) instead of a single dimethylformamide. This study was examined to the physico-chemical properties in single DMF and binary mixture DMF with MEK or TOL. Materials: Physico-chemical properties were measured by Korean and American Standard Test Methods. Results: Boiling point, specific gravity and flash point in single DMF were significantly higher than binary mixture DMF with MEK or TOL and such difference was dependent on the mixing ratio of MEK and TOL, and low explosion limit in binary mixture DMF with TOL was only significantly lower than single DMF. However, Reid vapor pressure had significantly higher in binary mixture DMF with MEK or TOL compared with single DMF. Conclusions: Our results demonstrate that the binary mixture DMF with MEK or TOL synergistically increases volatilization of DMF. It was concluded that the interaction between DMF and MEK and/or TOL might play a key role in the volatilization process of DMF under environmental conditions of workplace.

• Toxicological Research
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• v.32 no.4
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• pp.337-343
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• 2016

We determined the toxicity of mixtures of ethyl acetate (EA), isopropyl alcohol (IPA), methyl ethyl ketone (MEK), toluene (TOL) and xylene (XYL) with half-maximal effective concentration ($EC_{50}$) values obtained using human hepatocytes cells. According to these data, quantitative property-activity relationships (QPAR) models were successfully proposed to predict the toxicity of mixtures by multiple linear regressions (MLR). The leave-one-out cross validation method was used to find the best subsets of descriptors in the learning methods. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP) and flash point (FP) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of EA and IPA was significantly lower than that of contained TOL and XYL. The mixture toxicity was related to the mixing ratio of MEK, TOL and XYL (MLR equation $EC_{50}=3.3081-2.5018{\times}TOL-3.2595{\times}XYL-12.6596{\times}MEK{\times}XYL$), as well as to BP, SG, VP and FP (MLR equation $EC_{50}=1.3424+6.2250{\times}FP-7.1198{\times}SG{\times}FP-0.03013{\times}rVP{\times}FP$). These results suggest that QPAR-based models could accurately predict the toxicity of polar and nonpolar mixtures used in rotogravure printing industries.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3637-3641
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• 2014

In this study, we analyzed the toxicity of mixtures of dimethylformamide (DMF) and methyl ethyl ketone (MEK) or DMF and toluene (TOL) and predicted their toxicity using quantitative structure-activity relationships (QSAR). A QSAR model for single substances and mixtures was analyzed using multiple linear regression (MLR) by taking into account the statistical parameters between the observed and predicted $EC_{50}$. After preprocessing, the best subsets of descriptors in the learning methods were determined using a 5-fold cross-validation method. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP), flash point (FP), low explosion limit (LEL), and octanol/water partition coefficient (Pow) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of DMF and TOL was significantly lower than that of DMF. The mixture toxicity was directly related to the mixing ratio of TOL and MEK (MLR $EC_{50}$ equation = $1.76997-1.12249{\times}TOL+1.21045{\times}MEK$), as well as to SG, VP, and LEL (MLR equation $EC_{50}=15.44388-19.84549{\times}SG+0.05091{\times}VP+1.85846{\times}LEL$). These results show that QSAR-based models can be used to quantitatively predict the toxicity of mixtures used in manufacturing industries.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.220-229
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• 1997

Extraction of valuable light hydrocarbon from atmospheric residue using pentane as a solvent has been carried out. The SIMDIS was used to calculate the true boiling point of atmospheric residue containing complex components before the modeling of the extraction process could by performed. In order to simplify the procedure, modeling was adopted and a lumping method was used, such that a large number of compounds were divided into similar component classes called pseudocomponents. The modeling of the extraction process of the atmospheric residue-pentane system was based on the isothermal flash calculation, and the Peng-Robinson equation of state was used to calculate the fugacity coefficient of vapor and liquid phase during calculation steps of modeling. The agreement between the experiments and the calculations was reasonable considering the uncertainties involved in modeling such complex processes.

• Analytical Science and Technology
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• v.6 no.1
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• pp.65-75
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• 1993

A number of alternative cleaning solvents to CFC 113 which was identified as a ozone-depleting meterial were collected to measure their experimental physecal properties of density, surface tension, Refractive Index, boiling point, pH, viscosity, flash point, and soltbility. They might be classified as aqueous, simi-aqeous, alcohol ketone, and halogen cleaning solvents. The solubilities of abietic acid, a major component of flux used in PCB (Printed Circuit Board) of the electronic indystry, into the cleaning solvents including CFC 113 were determined for comparison. The assorted cleaning solvents have their own advantages and disadvantages. Therefore a end-user carefully needs to choose the best-fit cleaning solvent after the safety, stability, and economics as well as the effectiveness by physical properties of the alternative cleaning solvents are integratedly considered.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.73-80
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• 2002

Dimethyl ether (DM) is one of the most attractive alternative fuel far compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 ㎜/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was farmed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.9-17
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• 2013

Butanethiol is known as a typical odorant with hydrogen sulfide, methyl mercaptan, methyl sulfide, but on the physical and chemical properties and biological hazard assessment, including inhalation toxicity data are very scarce. Butanethiol as a colorless transparent liquid, and has physic-chemical characteristics with flash point as $-23^{\circ}C$ and strong fire risk, boiling point $84-85^{\circ}C$, vapor pressure 80.71 mmHg ($25^{\circ}C$), freezing point $-140.14^{\circ}C$. From whole body exposure with SD rats, the $LC_{50}$ is above 2,500 ppm (9.22mg/L), and then it is classified as the acute toxic chemical (inhalation) category 4 according to the governmental notification No. 2012-14.