• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.592-601
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• 2013

This work, which was about the synthesis of 3-(1,8-Naphthalimido) propyl methacrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect(Q), polar effect(e) and fluorescence effect of 1,8-naphthalicanhydride. Azobisisobutyronitronitryl(AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide(DMF) of solvent for the copolymerization of NIPM. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from F-R and K-T methods. NIPM was found to be more copolymerized than GMA. The fluorescence spectrums of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm.

• 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.

• Korean Journal of Poultry Science
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• v.40 no.3
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• pp.171-178
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• 2013

The purpose of this study was to evaluate the sperm viability, normal acrosome and mitochondrial activity in the frozen-thawed fowl semen by different cryoprotectants. The experiment was carried out on 10 sexually adult roosters of Ogye. The semen was collected twice a week and pooled semen was diluted 1:1 EK extender containing no cryoprotectant at $5^{\circ}C$. After equilibration for 30 minutes, diluted chicken semen was diluted 1:1 extender containing either 7% dimethylacetamide (DMA), 7% dimethylformamide (DMF) or 7.5% methylacetamide (MA) at final concentration and was put in 0.5 mL plastic straws and frozen for 30 minutes by exposure to liquid nitrogen vapor 4 cm above the surface of liquid nitrogen, followed by plunging into liquid nitrogen. Frozen semen was thawed in water bath at $5^{\circ}C$ for 2 minutes. For cytometric analysis, the frozen-thawed semen was diluted with EK extender to a final concentration of 90 million spermatozoa per mL. Sperm membrane integrity was evaluated as SYBR-14 and propidium iodide (PI). Acrosome integrity was assessed with fluorescein isothiocyanate-labeled PSA and PI. The percentage of mitochondrial function was estimated by using Rhodamine123 (R123) and PI. In conclusion, freezing rooster semen by using 7% DMF as cryoprotectant was significantly highest in rates of survival and mitochondrial function while its rate of damage of acrosome was significantly lowest. As a result, DMF is the cryoprotectant that has the lowest influences on sperm membranes and acrosome integrity. Therefore it could be used for freezing method of animal genetic conservation method for poultry diversity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.4
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• pp.303-309
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• 2008

The reduction of risk within the workplace has long been focus of attention both through industry initiatives and legislation. Exposure matrices according to industries and processes treated DMF (N,N-Dimethylformamide) were constructed based on KOSHA (Korean Occupational Safety and Health Agency)'s 2005 exposure database which were gathered from Korean agencies of workplace hazards evaluation for business place. These exposure matrices were assessed by danger value (DV) that was calculated from combination of hazard rating, duration of use rating, and risk probability rating of exposure to chemical hazardous agents in accordance with Hallmark Risk Assessment Tool. The results of risk assessment is divided four kinds of control bands which were related with control measures. The applicability of risk assessment using exposure matrices was performed by field study and survey for high matrices group. This study found that more attentions should be paid to two industries, manufacture of sewn wearing apparel and manufacture of textiles, among 19 industries, and to 3 processes, coating, processing & mixing, and lab, among 80 processes because those were regarded as having the highest risk.

• Membrane Journal
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• v.6 no.2
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• pp.96-100
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• 1996

In order to improve the permeability of the homogenous membrane of poly(carbobenzoxy-L-lysin)(PCLL), which has very high selectivity of helium gas to nitrogen gas, asymmetric porous membranes of PCLL were prepared by casting from 20% solutions in dioxane and dimethylformamide(DMF), respectively. The membranes were characterized by measuring the number of the pores, the pore size distribution of the surface(the skin layer) and the thickness of the skin layer by scanning electron microscope and transmission electron microscope. The mean pore size and the pore density were lower for the membrane cast from dioxane than that from DMF, which was explained by the mechanism of the formation of the pores in the asymmetric porous membrane. The permeability coefficient observed could be roughly explained by the viscous flow through the skin layer. However, the selectivity observed was against the theory of the viscous flow.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.3-18
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• 1997

This study was conducted to evaluate desorption efficiencies by types of desorption solvent for polar and non-polar organic compounds collected on activated charcoal tubes. Analytes tested were toluene, m-xylene, isobutyl alcohol, n-butyl alcohol, cellosolve acetate, and butyl cellosolve. Three different concentration levels of spiked sample were made. Types of cosolvent mixed with the main solvent, $CS_2$, were methanol, pentanol, and dimethylformamide (DMF) and the cosolvent for methylenechloride was methanol. The amounts of cosolvent added to the main solvent were 1, 5, and 10% by volume (v/v%), respectively. The results were as follows: 1. For all mixed solvents except 1% methanol and 1% pentanol with $CS_2$, desorption efficiency significantly increased, compared with that of $CS_2$ alone. 2. Desorption efficiency increased by increasing analyte loading on charcoal tube regardless of mixed solvents used and the material polarity. 3. For all cosolvents mixed with $CS_2$ by 1% and 5% volume, desorption efficiency for non-polar compound was significantly higher than that of polar compound. For the 10% mixed solvents and the methylenechloride mixed with methanol, the results were opposite. 4. The lowest mean percent bias of 4.79% was obtained from the 5% DMF-$CS_2$ mixed solvent, followed by 4.82% from the 10% DMF-$CS_2$ solvent while the highest bias of 23.26% was from the solvent of $CS_2$ alone. Based on the results of this study, in order to increase desorption efficiency, it is recommended to add such cosolvents as methanol, pentanol, and DMF to $CS_2$, preferably 5% by volume for analyzing polar compounds collected in charcoal tubes.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.364-372
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• 2012

Transient mixing states of two different fuel oils, dimethylformamide (DMF) oil and JetA1 oil, were investigated by using a color image processing and a neural network. A tank ($D{\times}H$, $310{\times}370mm$) was filled with JetA1 oil. The DMF oil was filled at a top tank, and was mixed with the JetA1 oil in the tank mixing tank via a sudden opening which was performed by nitrogen gas with 1.9 bar. An impeller was rotated with 700 rpm for mixing enhancements of the two fuel oils. To visualize the mixing state of the DMF oil with the JetA1 oil, the DMF oil was coated with Rhodamine B whose color was red. A LCD monitor was used for uniform illumination. The color changes of the DMF oil were captured by a camcoder and the images were transferred to a host computer for quantifying the information of color changes. The color images of two mixed oils were captured with the camcoder. The R, G, B color information of the captured images was used to quantify the concentration of the DMF oil. To quantify the concentration of the DMF oil in the JetA1 oil, a calibration of color-to-concentration was carried out before the main experiment was done. Transient mixing states of DMF oil with the JetA1 oil since after the sudden infiltration were quantified and characterized with the constructed visualization technique.

• Membrane Journal
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• v.31 no.4
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• pp.282-292
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• 2021

In this work, we tested commercial organic solvent nanofiltration (OSN) membranes using both in-house dead-end and crossflow systems. Four different crosslinked polyimide Duramem (DM) OSN membranes with various MWCO (molecular weight cut off) values were tested in organic solvents such as ethanol, N,N-dimethylformamide, acetone and acetonitrile. The membranes exhibited more reliable and reproducible performance in the crossflow system, and the performance changed significantly depending in the physical properties of the testing solvent. This is due to the initial stabilization period via pressure-induced compaction phenomenon, which can be vastly different between membrane samples. Hence, to obtain reliable and reproducible results, crossflow system is the preferred choice.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.414-419
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• 1975

The insoluble tungsten complexes with 8-hydroxy quinoline (oxine=Hox), aniline (A), and pyridine(Py) in several organic solvents have been synthesized. Using the different solvents with oxine, two different complexes have been synthesized in dichloromethane and dimethylformamide(DMF), respectively. Only one kind of complex has been synthesized with aniline in dichloromethane and with pyridine in acetone. The complexes may be formulated as $WCl_2(Hox)_2,\;[WO_2(Ox_2)],\;[WCl_3A_3],\;and\;[WO_2ClPy]$ by the results of elemental analysis, infrared spectral data, and thermogravimetric analysis.

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.260-266
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• 1990

The electrochemical behavior of N-methyl-2-amino-l-cyclopentene-l-dithiocarboxylic acid $(N-CH_3 acdc) and 2-amino-l-cyclopentene-l-dithiomethyl ester (S-CH_3 acdc) in DMF have been investigated by the use of polarography, cyclic voltammetry and coulometry. The dimer of N-CH_3 acdc is further oxidized at +0.98 V via 2-electron process to produce free sulfur atom and cyclization product. The ring formation between two dithio group occurs along with the elimination of one sulfur atom. The elimination of sulfur atom occurs via two electron oxidation process at + 0.98 V vs. Ag/AgCl electrode. However, the cyclization does not occur in the S-CH_3$ acdc.