• Bulletin of the Korean Chemical Society
• /
• v.23 no.8
• /
• pp.1149-1153
• /
• 2002

CH4/CO2 dry reforming was carried out to make syn gas on the Ni/Al2O3 catalysts calcined at different temperatures. The Ni/Al2O3 (850 $^{\circ}C)$ catalyst gave good activity and stability w hereas the Ni/Al2O3 $(450^{\circ}C)$ catalyst showed lower activity and stability. The NiO/Al2O3 catalyst calcined at $850^{\circ}C$ for 16 h (Ni/Al2O3 $(850^{\circ}C))$ formed the spinel structure of nickel aluminate, which was confirmed by TPR. The carbon formation rate on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was very low till 20 h, and then steeply increased with reaction time without decreasing the activity for CH4 reforming. The Ni/Al2O3 $(450^{\circ}C)$ catalyst showed high carbon formation rate at the initial reaction time and then, the rate nearly stopped with continuous decreasing the activity for CH4 reforming. Even though the amount of carbon deposition on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was higher than that on the Ni/Al2O3 $(450^{\circ}C)$ catalyst, the activity for CH4ing was also high, which could be attributed to the different type of the carbon formed on the catalyst surface.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.5
• /
• pp.364-368
• /
• 2007

The objective of this study was to characterize organic mater decomposition with application of livestock manure compost in upland soil. Six different composts, which were chicken (CHM), pig (PIM), and cow (COM) manure compost added and chicken (CHMS), pig (PIMS), cow (COMS) manure compost with sawdust added, were prepared for this study. These composts have different composition of crude carbohydrate (hemicellulose, cellulose, and lignin). The buried-bag method was used to determine the rate of organic mater decomposition and the changes of crude carbohydrate content during 36 months in the field. In all treatment, hemicellulose content was sharply decreased within 8 months, but considerable amount of lignin was remained after 36 months. After 40 months, the rates of carbon decreasing were 81, 80, 72, 69, 67, and 64 % for CHM, PIM, COM, CHMS, PIMS, and COMS, respectively. The estimated equation of carbon decreasing rate (D), $D=aT^b$, was fit to the carbon decreasing rate vs. elapsed time (T) using a non-linear regression procedure. After 40 months, significant difference of carbon decreasing rate between observed and estimated was not found. The relationship between constant a, b and hemicellulose content in the compost was not observed in this experiment. The cellulose and lignin content in the compost were positively correlated to the constant b and negatively correlated to the constant a.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.10a
• /
• pp.456-459
• /
• 2005

Continuous cooling transformation behaviors were studied fur low carbon HSLA steels containing three different level $(1\~3\;wt\%)$ of Ni addition. Thermo-mechanical processing (TMP) simulations to construct continuous cooling (CCT) diagram were conducted by using Gleeble system. As cooling rate increased, pearlite, granular bainite, acicular ferrite, bainitic ferrite and lath martensite were transformed from deformed austenite. Fully bainitic microstructure were developed at all cooling rate condition in high Ni containing steel due to hardenability increasing effects of Ni. Ni also influenced the transformation kinetics. At the slowest cooling rate of $0.3^{\circ}C/s$, transformation delayed with decreasing Ni contents because of the diffusion of substitutional alloy elements. However, cooling rate slightly increased to $1^{\circ}C/s$, transformation kinetics accelerated with decreasing Ni contents because nucleation of bainite was sluggish due to hardening of residual austenite.

• Journal of Microbiology and Biotechnology
• /
• v.1 no.1
• /
• pp.75-78
• /
• 1991

The carotenoid biosynthesis of a red oleaginous yeast, Rhodotorula glutinis was significantly changed when the yeast was grown on different carbon substrates. The highest carotenoid production was obtained on culture medium containing glucose when the carbon to nitrogen ratio (C/N ratio) was adjusted to 25.7. Galactose stimulated the biosynthetic rate of torularhodin, a xanthophyll component of the yeast. With decreasing C/N ratio of the medium, significant changes of $\gamma$-carotene and torularhodin were observed such that increase in the torularhodin concentration was nearly equal to the decrease in $\gamma$-carotene. It was speculated that the nature of carbon substrate affected the metabolic rate of the cell, and accompanied by the different pattern of carotenoid accumulation in the cell.

• Journal of the Korean Society of Tobacco Science
• /
• v.20 no.1
• /
• pp.124-130
• /
• 1998

This study was conducted to evaluate the ability of anion generating air cleaner to remove gases, vapor and particles from closed room contaminated with environmental tobacco smoke (ETS). The measurements covered particle sizes of 13.8-542.5nm, particle concentration, surface area, volumes UVPM, FPM, solanesol, and the following gases and vapor; carbon dioxide, carbon monoxide, nicotine, and 3-ethenylpyridine. Tobacco smoke was generated and mixed in a closed room in which the airflow rates were in the range of 0.00-0.04 m/s. The anion generating air cleaner was startedl and the decay rates for the gases, vapor and particles were measured, When the use of anion generating air cleaner, solid components of ETS, such as respirable suspended particle (RSP), utraviolet particulate matter (UVPM, fluorescent particulate matter (FPM) and solanesol was sharply decreased, and vapor phase components of ETS, such as nicotines 3-ethenylpyidine were modelately decreased by time elapse. Even the use of anion generation air cleaner, the decreasing rate of carbon dioxide concentration was similar with control, and the decreasing rate of carbon monoxide was slower than that of control. Our results indicated that the use of anion generting air cleaner had an effect on reduction of solid and vapor components from ETs, but it had no effect on gaseous components of ETS.

• Journal of the Korean institute of surface engineering
• /
• v.21 no.2
• /
• pp.53-67
• /
• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.

• Journal of Environmental Health Sciences
• /
• v.19 no.2
• /
• pp.69-77
• /
• 1993

In the present study, the comparison of liver damage in carbon tetrachloride (CCl$_4$)-treated rats with that those pretreated with ethanol and an effect of liver injury on the serum and liver xanthine oxidase (XOD) activity were evaluated. The increasing rate of liver weight per body wt., the levels of serum alanine aminotransferase, and the decreasing rate of hepatic glucose-6-phosphatase activity and the protein contents in the liver cell were higher in carbon tetrachloride-treated animals pretreated with ethanol than the carbon tetrachloride-treated group. Especially, the histopathological findings also showed more severe liver damage in the ethanol-pretreated rats than the rats treated with carbon tetrachloride only. In such a experimental condition the xanthine oxidase activity of serum and liver both of carbon tetrachloride-treated rats and those pretreated with ethanol were higher than that of each control group. And the increasing rate of xanthine oxidase enzyme activity to the control group was higher in carbon tetrachloride-treated group pretreated with ethanol than those treated with CCl$_4$. In addition, the heptic uricase activity and the serum levels of uric acid were more increased in carbon tetrachloride-treated group pretreated with ethanol than those in the CCl$_4$-treated rats. On the other hand, there were no statistical differences in hepatic catalase and glutathione S-transferase activities between the CCl$_4$-treated rats and those pretreated with ethanol. In conclusion, it is assumed that the more severe liver damage in ethanol pretreated rats would be due to oxygen free radical produced by the xanthine oxidase system.

• Corrosion Science and Technology
• /
• v.2 no.4
• /
• pp.183-188
• /
• 2003

Corrosion of carbon and weathering steels were evaluated under 3 environmental exposures in Thailand (urban, rural and marine) for a year. The seasonal study was designed to determine different corrosion mechanisms by 6 months of dry season and 6 months of rainy season in a year. The sheltered exposure racks were used to determine the washing effect of min. At each site, climatic and pollutants analyses were carried out. The present study showed that the difference in corrosion rates of carbon and weathering steels was not so distinguished in both rural (AIT) and urban (TISTR) environments. The corrosion rate of weathering steel was somewhat lower than that of carbon steel and the decreasing tendency of corrosion rate with time was slightly higher for weathering steel than for carbon steel. In marine (Rayong) environment, the corrosion rate was higher and the effect of wet and dry seasons was observed. The corrosion rate in 6 dry months was higher for direct exposure than for sheltered exposure. However, in 6 rainy months. the corrosion rate of sheltered exposure was higher than that of direct exposure. In direct exposure for I year, that is, the first 6 dry months and the next 6 rainy months, the corrosion rate decreased with time. but in sheltered exposure, the corrosion rate did not decrease with time. instead, increased in the next 6 rainy months. This indicated that the protect ive layer formed in the first 6 dry months could be destroyed by high deposition of chloride to r sheltered exposure in the next 6 rainy months; whereas the rust layer for direct exposure could be kept sound due to washing effect in rainy season, even though the deposition rate of chloride was almost the same for direct and sheltered exposures. In marine environment, the weathering steel showed higher corrosion resistance than carbon steel but its corrosion rate was higher than those in other environments.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.231-234
• /
• 2000

Vertically aligned carbon nanotubes were synthesized on Ni-coated Si substrates using microwave plasma-enhanced chemical vapor deposition. The grain size of Ni thin films was varied with the RF power density during the RF magnetron sputtering process. It was found that the diameter, growth rate, and density of carbon nanotubes could be controlled systematically by the grain size of Ni thin films. With decreasing the grain size of Ni thin films, the diameter of the nanotubes decreased, whereas the growth rate and density increased. High-resolution transmission electron microscope images clearly demonstrated synthesized nanotubes to be multiwalled. The number of graphitized wall decreased with decreasing the diameter. Field emission properties will be further presented.

• Journal of the Korean Ceramic Society
• /
• v.21 no.2
• /
• pp.156-164
• /
• 1984

The characteristic of pyrolytic carbon deposited in a fluidized bed as measured by density apparent crystallite size and viewed metallographically under polarized light can be easily controlled by adjusting the deposition parameters such as deposition temperature and propane flow rate or silicon content. The density of isotopic pyrolytic carbons deposited from propane between 120$0^{\circ}C$ and 140$0^{\circ}C$ increases with increasing propane flow rate and decreasing deposition temperature from 1, 73g/cc to 2.08g/cc. The apparent crystallite size Lc parameter appears to depend only on deposition temperature being entirely independent of the propane flow rate. The carbon matrix density of the silicon-alloyed carbonds deposited from propane and methyltrichlorosil-ane from 2.05g/cc for a silicon content around 9wt% to 2.67g/cc for a silicon content of 36.7wt% The Lc parameter of the deposition temperature being entirely independent of the silicon content.