• Polymer Science and Technology
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• v.23 no.6
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• pp.615-623
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• 2012

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.4-5
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• 1992

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.702-707
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• 2005

Spinel $LiMn_2O_4$ has become appealing because manganese is inexpensive and environmentally benign. In general, cathodes for lithium ion batteries include carbon as a conductive agent that provides electron transfer between the active material and the current collector. In this work, we selected Acetylene Black and Super P Black as conductive agents, and then carried out their comparative investigation for the performances of the $Li/LiMn_2O_4$ cells using different conductive agents with different particle size. In addition, their electrochemical impedance characteristic of $Li/Mn_2O_4$ cells using different conductive agents is effectively identified through a.c. impedance technique. As a consequence, $Li/LiMn_2O_4$ cells with Super P Black show better electrochemical performances ascribed to the significant contribution of feasible ionic conduction due to larger particle size than those with Acetylene Black.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.16-21
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• 1992

Increase in nodulation and nitrogen fixation was achieved partly through the isolation of supernodulating soybean mutant plants. This experiment was conducted to compare nodulation, nitrogen fixation, and early growth characters of wild type 'Bragg' with those of its supernodulating soybean mutant, 'nts 382' and 'nts 246'. At 31 days after planting, nodule dry weight of nts mutants was 2.5 to 3.7 times greater than that of Bragg. Higher nodulation of nts mutants showed the reduced top growth, indicating that photosynthates might be translocated and used for nodule growth attached to the root system. Total acetylene reduction activity was higher in nts mutants than Bragg, whereas specific acetylene reduction activity of nts mutant was the half of that of Bragg. Mixture of nts mutants and Bragg did not affect nodulation characters each other, suggesting that factors affecting supernodulating characters exist inside rather than outside the root system.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.926-934
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• 1992

Uniform diamond films in a few $\textrm{mm}^2$ size and locally isolated diamond single crystals in size of 60 $\mu\textrm{m}$ were synthesized on Si-wafer and Al2O3 substrate by the method of acetylene flame. The effects of substrate temperature and flow ratio of oxygen to acetylene on the morphology of deposited diamond were investigated. According to the observations of growth behavior of diamond on Si substrate with respect to substrate surface pretreatment and flow ratio, it was shown that well faceted diamonds could grow uniformly when flow ratio was above 0.9 and substrates were densely scratched. With increasing substrates temperature, the crystal morphology changes from octahedron bounded by only {111} plane below 850$^{\circ}C$ to cubo-octahedron with almost equal development of {111} and {100} plane in the temperature range of 850∼950$^{\circ}C$. Between 950∼1050$^{\circ}C$, the {111} faces become rough and concave. Above 1050$^{\circ}C$, new crystallites begin to grow on concave {111} surface and overall morphology looks like cubo-octahedron with degenerated {111} faces. These changes of morphology can be understood in terms of the different growth mode of each crystallographic plane with respect to the substrate temperature and supersaturation. And the observed phenomena on {111} planes can be related to the face instability and twin generation.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.51-56
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• 2011

The various process parameters of thermal spray process affects on quality of Ni-based coatings. Thus, there is need to analyze the effect of process parameters on quality of Ni-based coatings. In this paper, the effects of process parameters on hardness and wear rate of Ni-based coatings were investigated using 4 design of experiments. First, the Ni-based coatings were fabricated according to $L_9(3^4)$ orthogonal array. The hardness tests and the wear tests were performed on the Ni-based coatings. The analysis of variance for the hardness and wear rate were carried out. As a results, the acetylene gas flow and the powder feed rate were identified as main factors effected on the hardness and the oxygen gas flow and the acetylene gas flow were identified as main factors effected on the wear rate. The full factorial experiments design with different levels was applied for investigation of effect of these main factors.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.20-24
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• 2012

Denitrification rate was determined for various freshwater wetland types in the Mississippi River Coastal delta plain. Site 1 and 4 were collected from forested-tupelo dominated wetland, and site 2 and 3 were from floating emergent marsh. The maximum $N_2O$ emission was $7.47mg\;N\;m^{-2}$ for site 1 at day 6 after the addition of nitrate, $6.96mg\;N\;m^{-2}$ for site 2 at day 4, $6.63mg\;N\;m^{-2}$ for site 3 at day 3, and $9.64mg\;N\;m^{-2}$ for site 4 at day 4. The denitrification rate was determined using the acetylene inhibition method $1.24mg\;N\;m^{-2}d^{-1}$ for site 1, $1.93mg\;N\;m^{-2}d^{-1}$ for site 2, $2.24mg\;N\;m^{-2}d^{-1}$ for site 3, and $2.78mg\;N\;m^{-2}d^{-1}$ for site 4. The maximum denitrification rate was in the order of site 4 > site 3 > site 2 > site 1.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.58-65
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• 2012

The influence of magnetic field on propane and acetylene diffusion flames have been experimentally investigated using an electromagnetic system. Periodically induced magnetic field having various frequencies and duty ratios was established in square wave form. The maximum intensity and gradient of magnetic field were 1.3 T and 0.27 T/mm, respectively. The width of a propane flame was reduced up to 4.5% and the brightness was enhanced up to 25% when the magnetic field was induced. The soot emission from an acetylene flame was ceased when magnetic field was induced. The alteration of flow field, which is due to the paramagnetic characteristics of oxygen molecule, is most likely to be responsible for the change in flame size and brightness. The effect of magnetic field on diffusion flames, which competes with the gravitational effect, was more apparent from a smaller size flame. The magnetic field effect, therefore, could be important under microgravity conditions. Since the time required to alter the flow field must be finite, the magnetic field effect is likely to be less significant for a periodically oscillating magnetic field at a high frequency or having a small duty ratio.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1913-1916
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• 1996

With a progress of electrical and electronic technology, radio-frequency circuits including high frequency components are widely applied to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of acetylene-air and ethylen-air mixtures experimentally based on the IEC 79-3 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a $10{\Omega}$, $20{\Omega}$, $30{\Omega}$, $40{\Omega}$ or $50{\Omega}$ resistor and a power amplifier with frequency range up to almost 1 MHz. Experimental results show that the ignition of the acetylene-air and ethylen-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit: the minimum ignition voltage increases gradually with the increase of the frequency.

• Polymer(Korea)
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• v.26 no.6
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• pp.778-784
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• 2002

Chemical modification of a dextran film to improve its physical properties was carried out by addition of plasticizers and crosslinking agents. Moreover, low-temperature plasma treatment with acetylene gas was done. The dextran film showed high mechanical strength but was brittle and vulnerable to moisture. When plasticizer was added, it became very soft but with large reduction of mechanical strength. However, a flexible film with fairly high mechanical strength and water resistance was prepared when the film was crosslinked by adding crosslinking agent with or after the addition of plasticizer. Treatment with an acetylene plasma changed the dextran film surface from hydrophilic to hydrophobic with little influence on the bulk properties of the film.