• The International Journal of Costume Culture
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• v.5 no.2
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• pp.53-65
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• 2002

Morphology of polyester fiber was physically modified by solvent treatment. PET fiber was treated with N,N-dimethylformamide (DMF) at 100, 120, $140^{circ}C$ for 10 minutes without tension. The structural changes in the morphology of DMF-induced modified PET fiber were FTIR and SEM analysis. Also dyeing behavior of DMF-treated polyester fibers with various disperse dyes was studied to detect changes of amorphous area in fine structure. DMF treatment resulted in increases in total void content, degree of crystallinity, trans isomer content, chain folding, segmental mobility and molecular packing, but it resulted in decreases in amorphous orientation, intermolecular forces and individual void size through longitudinal shrinkage, lateral welling and removal of oligomers. Void-size distribution could be estimated from the dye uptake with various sizes of disperse dyes. In contrast to the large increases in dye uptake with small dye molecules, there is no and little dye uptake with the bulkiest dye, which means that void size is bigger or smaller than the volume of each dye. Diffusion rates of dye molecules showed increases. This dyeing study revealed that the disperse dyeing is very effective method for characterizing the internal morphology of polyester fiber.

• Journal of the Korean institute of surface engineering
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• v.16 no.4
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• pp.188-194
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• 1983

The method of trivalent chromium plating has been studied. The relations between the mixing ratio of chromic chloride and DMF, and the corrosion resistance and throwing power of plated chromium have been investigated. As a result, the best result has been obtained, when the mole ratio of chromic chloride and DMF are 0.8 and 5.4M respectively, and it has been learned that the amounts of DMF added have particularly the delicate effects in chromium plating procedures. The results of measuring of pH and reduction potentials of chromium plating bath with addition of DMF showed that the functions of DMF have both the buffer actions for the solution and the complex formation of trivalent chromium.

• Polymer(Korea)
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• v.26 no.3
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• pp.360-366
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• 2002

The electrospinning of polyacrylonitrile dissolved in N,N-dimethyl formamide (DMF) successfully produced nano-scale fibers. The processing parameters such as charged voltage, velocity of collected roller, and tip-to-collector distance (TCD) , affected the ultimate fiber size. At TCD of 5 cm, the average tiber diameter increased with increasing charged voltage because of the more aggregation between fibers due to the remaining DMF solvent on the fiber surface. But, at TCD of 9 cm, the average fiber diameter decreased as the charged voltage was increased because of complete evaporation of DMF. Also, the fiber diameter decreased with increasing the velocity of collected roller. Cross direction width (CWD) of nonwoven mat increased with decreasing the charged voltage and with increasing TCD.

• Toxicological Research
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• v.30 no.3
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• pp.199-204
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• 2014

The aim of this research was to improve our understanding of human toxicity due to exposure to DMF, MEK, or TOL individually as compared to exposure to DMF-MEK or DMF-TOL mixtures, by comparing $EC_{50}$ values as well as the morphological changes in HepG2 cells treated with these substances. We found that there was marked cell necrosis in the groups treated with mixtures than in those treated with the compounds alone, and that the amount of cell death and the $EC_{50}$ value were more dependent on MEK and TOL than on DMF. Moreover, analysis of the changes in effective concentration curves revealed that MEK had an antagonistic effect on the human toxicity of DMF, whereas TOL had a synergistic effect. Accordingly, these results suggest that in workplaces involved in the manufacture of synthetic leather, mixtures of DMF and TOL should be avoided as much as possible in order to minimize environmental toxicity and protect the health of the workers.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.22-32
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• 2001

In this paper, we propose an average acquisition time and hardware design of high speed PN code synchronous acquisition system using DMF(Digital Matched Filter) with new switching method in DS-SS/CDMA(Direct Sequence Spread Spectrum Code Division Multiple Access). In reality, the PN code synchronous acquisition system using DMF has very complicated hardware, high cost and high power consumption. The PN code synchronous acquisition system using proposed switching method DMF can overcome those disadvantages. Therefore, we can make hardware simple and obtain low power and high density by reducing the area by 1/5 against the conventional approaches of using either the matched filters or the serial correlators. The proposed system architecture is also simple and easily controllable since there is no square-term circuit after execution of digital filtering.

• Fire Science and Engineering
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• v.33 no.4
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• pp.9-15
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• 2019

The flash points of DMF based organic solvent mixtures used in the synthetic leather manufacturing process were measured. The test group was composed of seven types of solvent mixtures, which included DMF, toluene, and MEK. Each flash point was tested according to the international standard test methods of KS M 2010. The flash points were then predicted using some prediction models and compared with the measured data. From the analysis results, the binary mixtures with a mole ratio of less than approximately 0.7 showed that the measured values were under 25 ℃. This showed that the expectation for the flammable risk lowering effects due to the mixing of high flash point materials was reduced. In addition, the predicted values were evaluated using the average absolute deviation (A.A.D). The results showed that the Le Chatelier's models had an "A.A.D" of 1.95 ℃ and were the closest to the measured values.

• Journal of Preventive Medicine and Public Health
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• v.32 no.1
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• pp.88-94
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• 1999

Objectives. In order to gain a better understanding of the mechanism of DMF toxicity, recent studies have focused on hepatic drug metabolizing enzymes. In this study, we investigated the effects of DMF on the induction of P450 and the activities of other related enzymes in rat liver microsomes. Methods. DMF was administered to male Sprague Daweley rats by intraperitoneal injection at 0(control), 450(D1), 900(D2), 1,800(D3) mg DMF/kg body weight in olive oil once a day for three days. Hepatic P450 was measured by method of Omura and Sato. We evaluated selective assays for the three drug metabolizing cytochrome P450 isoenzymes 1A1, 2B1 and 2E1. Results. The content of microsomal protein, P450 and b5 were tended to be decreased in DMF treated group, but they were not statistically significant. The activity of NADPH-cytochrome P450 reductase was significantly increased dose dependently(p<0.01), but the activity of NADH-b5 reductase was decreased in the treated group(p<0.01). The activities of PROD and EROD were not significant between control and treated group. The activities of pNPH in the DMF treated groups were higher than that of the control group(p<0.01). When Western immunoblottings were carried out utilizing three monoclonal antibodies which were specific against P4501A1/1, P4502B1/2 and P4502E1, the strong density band corresponding to P4502E1 was observed with the microsomes obtained from the rats treated with DMF. But there were no significant increased in the P4501A1/2 and P4502B1/2 band densities in immunoblotting. Conclusions. These result suggested that P4502E1 was inducible by DMF and P4502E1 isozyme might be responsible for the hydroxylation of DMF to HMMF.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.594-599
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• 2011

$SrAl_2O_4:Eu$ green phosphor was prepared by spray pyrolysis and its luminescence properties were controlled by replacing the Al sites with boron and using organic modifier or drying control chemical additive. It was clear that the substitution of B into the Al sites was helpful to obtain pure monoclinic $SrAl_2O_4$ phase and greatly enhance the emission intensity. In terms of the emission intensity, the optimal content of boron was about 1 at% with respect to the aluminum element. The luminescence intensity of $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ phosphor could be improved by the use of 0.2 M organic additives in the spray solution. Futhermore, using 0.5 M dimethylformamide(DMF) as a drying control chemical with organic additives made it possible to improve about 172% the emission intensity of $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ phosphor. According to XRD analysis, the organic additive and DMF used enhanced the crystallinity without any change in the crystal phase. When used only the organic additive without DMF, the surface area of the prepared $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ phosphor became enlarged. The use of DMF with the organic additive resulted in significant reduction in the surface area. It was concluded that the increase of the crystallinity as well as the reduction of surface area mainly contribute to the improvement in the luminescence intensity of $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ phosphor prepared using DMF and organic additives.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.582-587
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• 1989

Rates for aquation of $[Cr(NH_3)_5(DMF)]^{3+}$ ion in aqueous acidic solution have been measured by spectrophotometric method at various temperatures and pressures. The volume of activation for the aquation is small negative and lies in the limited range -2.76 ∼ -3.65 $cm^3mol^{-1}$. The entropy and compressibility coefficient of activation are small negative values. From the results of thermodynamic activation parameters, it can be inferred that the aquation of $[Cr(NH_3)_5(DMF)]^{3+}$ ion proceeds through an associative interchange($I_a$) mechanism.

• Journal of Korean Society for Quality Management
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• v.45 no.4
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• pp.769-780
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• 2017

Purpose: The aim of this study is to conduct a survey of dimethylformamide(DMF) content in polyurethane(PU)-based consumer products and provide the information for the PU manufacturer and company to prepare a countermeasure for improving the quality competitiveness. Methods: This study selected PU-based consumer products(toddler shoes, children's bag, children's play mat, safety gloves), which is closely used in everyday life, and analyzed the residual DMF content in the consumer products. Results: In this study, it was confirmed that the average DMF content of toddler shoes, children's bag, children's play mat and safety gloves are 38 ppm, 119 ppm, 396 ppm and 826 ppm, respectively. In addition, most of the samples were found to meet the internationally accepted standard of 1,000 ppm and the DMF contents were reduced from at least 63 % to 85 % with a single washing process. Conclusion: The domestic PU manufacturers should seek ways to reduce the DMF through their production facility applications and introducing new materials such as water-soluble PU, and preparing the process development for their quality competitiveness.