• 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.

• The Journal of the Korean dental association
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• v.22 no.12 s.187
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• pp.1059-1066
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• 1984

As an appraisal of Water Fluoridation Program in Chungju, fluoride content in the water of that city was examined, and 1176 K primary school children aged from 6 to 13 were surveyed on their oral hygiene status. The results were as followings: 1. Fluoride content ............ 0.8 ppm 2. dmf rate ............ 59.27% DMF rate ............ 39.46% 3. dmf t rate/index ............ 27.75%/2.40 dmf s rate/index ............ 11.91%/5.14 4. DMF T rate/index ............ 6.12%/0.93 DMF S rate/index ............ 1.65%/1.26

• Textile Coloration and Finishing
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• v.16 no.1
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• pp.59-64
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• 2004

As a simulation of solvent-assisted dyeing, the solvent effects on the structure of polyethylene terephthalate(PET) film treated by dimethylformamide(DMF) were investigated. The effects were evaluated by the atomic force microscopy(AFM) topographical changes and FT-IR spectrum analysis. PET films treated with DMF at $70^{\circ}C$ for several different treatment time(20, 40, and 60 min). AFM topography showed that, with increasing treatment time by DMF, PET surfaces became smooth due to the swelling phenomenon and the rigid structure changed into flexible state which was contributed to increase the surface area of PET films. FT-IR spectrum analysis showed that DMF and molecular chains of PET interacted each other via their polar carbonyl groups and that DMF also affected the out-of-plane bending vibration mode of phenyl ring of PET.

• Textile Coloration and Finishing
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• v.14 no.5
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• pp.277-283
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• 2002

Poly(ethylene terephthalate)(PET) filaments of regular(monodenier 2.08d) and ultramicrofiber (monodenier 0.05d) were treated with dimethylformamide(DMF) to observe the structure change of the PET such as shrinkage, density, X-ray diffraction of the UMF treated with DMF were measured. Also, dyeing experiments were performed to see the effects of DMF. The dyeability was improved by DMF treatments, and the equilibrium dye uptake increased in spite of the increase in the density and birefringence and crystallinity. The heat shrinkage appeared in PET UMF treated PET UMF treated with DMF at $80^\circ{C}$ by TMA, DSC, and Reovibron analysis and $T_m$ peak was shown by DSC analysis.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.89-102
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• 1981

1147 preschool children aged from 3 to 6 living in some farm villages in Kyungki-do were surveyed on dmf and distribution of dental caries in primary dentition. The results were as follows: 1. dmf rate ... 92.76 % boy ... 94.52 % girl ... 90.5.5 % 2. dmf t rate ... 37.07 % dmf t index ... 7.09 3. dmf s rate ... 13.74 % dmf s index ... 13.14 % 4. df t index ... 6.94 5. Each percentage of d, m & f per dmf teeth d rate ... 89.96 % m rate ... 7.24 % f rate ... 2.67 % 6. Most frequent site of dental caries in each tooth $\underline{A}$ mesial $\overline{A}$ distal $\underline{B}$ mesial $\overline{B}$ distal $\underline{C}$ distal $\overline{C}$ distal $\underline{D}$ disto-occlusal $\overline{D}$ disto-occlusal $\underline{E}$ linguo-occlusal $\overline{E}$ occlusal 7. Order of caries susceptibility $\overline{E}$ $\underline{E}$ $\overline{D}$ $\underline{D}$ $\underline{A}$ $\underline{B}$ $\overline{C}$ $\underline{C}$ $\overline{B}$ $\overline{A}$ 8. All the values in caries criteria showed a marked increae from those of 1968.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.345-350
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• 1992

Proton lineshapes and chemical shifts of paramagnetic solutions of Ln$(NO_3)_3$ in DMF have been measured over the temperature range 240K to 3807K. Solvation sphere exchange rates and the thermodynamic exchange parameters for CHO group of the DMF molecules have been extracted from these data. The results were established through a detailed analysis and discussion of the temperature depending data of the 1/$T_2$ and ${\Dellta}{\omega}$ data were analyzed in detail, and it has been found that delocalization of the unpaired electron spin from some $Ln^{3+}$ ion to DMF molecules beyond the first solvation shell would occur, giving rise to a scalar relaxation contribution in the bulk solvent.

• The Journal of the Korean dental association
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• v.21 no.12 s.175
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• pp.979-984
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• 1983

As an appraisal of Water Fluoridation Program in Chungju, fluoride content in the water of that city was examined, and 1317 K primary school children aged from 6 to 13 were surveyed on their oral hygiene status. The results were as follows: 1. Fluoride content ....................... 0.8 ppm 2. dmfrate ..................................... 81.17% DMF rate .......................................... 38.88% 3. dmf t rate/index ................................ 29.17%/2.55 dmf s rate/index ............................... 14.33%/6.27 4. DMF T rate/index ............................. 6.32%/0.92 DMF S rate/index ............................ 1.86%/1.35

• Journal of the Korean Chemical Society
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• v.25 no.6
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• pp.376-382
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• 1981

The rates and the activation parameters for the reaction of phenacyl bromide with substituted anilines in methanol and dimethylformamide were measured. The effects of substituted anilines were discussed. The rate of the reaction was increased with the electron donating power of substituent and showed larger value in DMF than in MeOH. The isokinetic relationship was shown between ${\delta}H^{\neq}$ and ${\delta}S^{\neq}$, isokinetic temperature was 539 and $400^{\circ}C$ in MeOH and DMF respectively, but p-nitro aniline was deviated from linearity in both solvents caused by solvent effects. The excellent linear relationship between log k and p$K_a$ of substituted anilines was observed by following equation. log k = 0.57p$K_a$-1.28 (r = 0.996) in MeOH at $45^{\circ}C$, log k = 0.65p$K_a$-0.88 (r = 0.970) in DMF at $45^{\circ}C$. From the Hammett plot, this reaction was a nucleophilic displacement of aniline to phenacyl bromide and the following equation was obtained at $45^{\circ}C$. log k/$k_0$ = -2.00${\sigma}$ + 0.06 (r = 0.985) in MeOH; log k/$k_0$ = -2.22${\sigma}$ + 0.08 (r = 0.995) in DMF. Large deviation of p-nitro aniline in DMF is resulted from solvent effects too. From above results, the substituent effect of this reaction can be described as $S_N2$ mechanism and bond formation more proceeds in DMF relative to MeOH.

• Advances in environmental research
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• v.7 no.1
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• pp.39-52
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• 2018

Direct membrane filtration (DMF) of wastewater has many advantages over conventional biological wastewater treatment processes. DMF is not only compact, but potentially energy efficient due to the lack of biological aeration. It also produces more biosolids that can be used to produce methane gas through anaerobic digestion. Most of ammoniacal nitrogen in wastewater is preserved in effluent and is used as fertilizer when effluent is recycled for irrigation. In this study, a technical feasibility of DMF was explored. Organic and nitrogen removal efficiencies were compared between DMF and membrane bioreactor (MBR). Despite the extremely high F/V ratio, e.g., $14.4kg\;COD/m^3/d$, DMF provided very high COD removal efficiencies at ~93%. Soluble microbial products (SMP) and extracellular polymeric substances (EPS) were less in DMF sludge, but membrane fouling rate was far greater than in MBR. The diversity of microbial community in DMF appeared very narrow based on the morphological observation using optical microscope. On the contrary, highly diverse microbial community was observed in the MBR. Microorganisms tended to form jelly globs and attach on reactor wall in DMF. FT-IR study revealed that the biological globs were structurally supported by feather-like materials made of secondary amines. Confocal laser scanning microscopy (CLSM) study showed microorganisms mainly resided on the external surface of microbial globs rather than the internal spaces.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.80-90
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• 2008

This study was carried out to investigate the correlation of urinary NMF concentration in workers exposed to DMF and concentration of DMF in the workplace. Samples were collected in workers exposed to high dose solvent in the synthetic leather factory by using silicagel tubes for 5-15 minutes, and were analyzed by GC. Geometric mean concentrations of DMF in the workplaces were 4.67 ppm in normal operation and 63.95 ppm in high exposure operation. The concentration of case uppers and machine cleaning process were more than 100 ppm in short time. The correlation of urinary NMF in workers and DMF in workplace was statistically significant in normal operation and high exposure operation. Correlation coefficient are 0.215(p<0.05) and 0.263(p<0.05). The result implied that STEL of DMF should be established in normal operation processes as well as high exposure operation processes.