• Proceedings of the KSME Conference
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• 2001.06a
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• pp.181-186
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• 2001

JLF-1 steel (Fe-9Cr-2W-V-Ta), low activation ferritic steel, is one of the promising candidate materials fer fusion reactor applications. High temperature fatigue life and tensile strength of JLF-1 steel and its TIG welded joints were investigated at the room temperature and $400^{\circ}C$. The strength of base metal (JLF-1) is in between those of weld metal and the HAZ. When the test temperature was increased from room temperature to $400^{\circ}C$, both strength and ductility decreased for base metal, weld metal and the HAZ. The longitudinal specimens of base metal showed similar strength and ductility compared with those of the transverse specimens at room temperature and $400^{\circ}C$. Little anisotropy was observed in the JLF-1 steel base metal in terms of rolling direction. Fatigue limit of weld metal which was obtained from cross-weld specimen is 495MPa. Thus, the weld metal showed the higher fatigue limit than those of base metal at both room temperature and $400^{\circ}C$. Little anisotropy of fatigue properties was observed for JLF-1 base metal in terms of rolling direction. When the test temperature was increased from room temperature to $400^{\circ}C$, the fatigue limit of both base metal and weld metal decreased substantially.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1161-1168
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• 1999

The redox property of oxide materials of the 3rd period transition metals(Cr~Zn), V, Mo, and W was studied with temperature-programmed reduction/temperature-programmed oxidation(TPR/TPO) experiment. The peak temperatures of TPO spectra were equal to or lower than those of TPR spectra. And the peak shapes of TPO spectra were broader than those of TPR ones. The activation energies of TPR/TPO for the oxides of the 3rd period transition metals showed in the range of 33~149 kJ/mol, while for the oxides of V, Mo, and W, they showed relatively higher values. The change of activation energies of TPR/TPO with various metal oxides showed a similar trend to the change of their metal-oxygen bond strengths. The change of activation energies of o-xylene oxidation for various metal oxides was proportional to the difference (${\Delta}E_a$) between the activation energy of TPR and that of TPO. From these results, we concluded that the oxidation of o-xylene over various metal oxide catalysts follows the Mars-van Krevelen mechanism including the surface reduction-oxidation of the metal oxide itself.

• Journal of Environmental Science International
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• v.10 no.5
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• pp.373-380
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• 2001

In recent years, the demand of activated carbon has been increasing steadily because of the environmental problems. Among them waste and water treatment and removal of poisonous gas were invorved. Therefore, in this study, activated carbon was made from the waste chinese cabbage and measured the iodine adsorption ability, carbonization yield, and activation yield of the produced activated carbon. The result showed that the carbonization yield was decreased when carbonization temperature was increaed and that the optimal carbonization temperature was $600{\circ}C$. The optimal concentration of NaOH for removing ash in the raw sample was 1~2N. The range of iodine adsorption number of activated carbon using chinese cabbage at $600{\circ}C$. carbonization was 610.82mg/g to 1019.58mg/g. The activation result of carbonization sample showed that the optimal activation condition was the carbonization at $400\circ}C$ and the activation at$700{\circ}C$. So the production of activated carbon using chinese cabbage was possible in the aspect of reuse of resource and decrease of environmental pollution compared to the commercial activated carbon.

• Carbon letters
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• v.10 no.4
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• pp.293-299
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• 2009

Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at $-196^{\circ}C$. The adsorption of iodine and methylene blue was also investigated at $30^{\circ}C$. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to $800^{\circ}C$. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.539-542
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• 2001

In SiC semiconductor device processing, it needs high temperature anneal for activation of ion implanted dopants. The macrosteps, 7~8nm in height, are formed on the surface of SiC substrates during activation anneal. We have investigated the effect of thermally-grown SiO$_2$layer on the suppression of macrostep formation during high temperature anneal. The cap oxide layer was found to be efficient for suppression of macrostep formation even though the annealing temperature is as high as the melting point of SiO$_2$. The thin cap oxide layer (10nm) was evaporated during anneal then the macrosteps were formed on SiC substrate. On the other hand the thicker cap oxide layer (50nm) remains until the anneal process ends. In that case, the surface was smoother and the macrosteps were rarely formed. The thermally-grown oxide layer is found to be a good material for the suppression of macrostep formation because of its feasibility of growing and processing. Moreover, we can choose a proper oxide thickness considering the evaporate rate of SiO$_2$at the given temperature.

• Journal of the Korean institute of surface engineering
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• v.25 no.4
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• pp.189-206
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• 1992

The effect of activation and electroless nickel plating conditions on contact properties was investi-gated for selective electroless nickel plating of Si wafers in order to obtain an optimum condition of con-tact hole filling. According to RCA prosess, p-type silicon (100) surface was cleaned out and activated. The effects of temperature, DMAB concentration, time, and strirring were investigated for activation of p-type Si(100) surface. The optimal activation condition was 0.2M HF, 1mM PdCl2, 2mM EDTA,$ 70^{\circ}C$, and 90sec under ultrasonic vibration. In electroless nickel plating, the effect of temperature, DMAB concentra-tion, pH, and plating time were studied. The optimal plating condition found was 0.10M NiSO4.H2O, 0.11M Citrate, pH 6.8, $60^{\circ}C$, 30minutes. The contact resistance of films was comparatively low. It took 30minutes to obtain 1$\mu\textrm{m}$ thick film with 8mM DMAB concentration. The film surface roughness was improved with decreasing temperature and decreasing pH of the plating solution. The best quality of the film was obtained at the condition of temperature $60^{\circ}C$ and pH 6.0. The micro-vickers hardness of film was about 800Hv. Plating rate of nickel on the hole pattern was slower than that of nickel on the line pattern.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.109-112
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• 2018

Optical properties of InAs/GaAs submonolayer-quantum dot (SML-QD) have been investigated using excitation intensity ($I_{ex}$)- and temperature-dependent photoluminescence (PL). At a low temperature (13 K) strong PL was observed at 1.420 eV with a very narrow full-width at half maximum, of 7.09 meV. The results of the $I_{ex}$ dependence show that the PL intensities increase with increasing $I_{ex}$. The enhancement factors (k) of PL increment as a function of $I_{ex}$ are 3.3 and 1.22 at low and high $I_{ex}$ regime, respectively. The high k value at low $I_{ex}$, implies that the activation energy of the SML-QDs is low. The calculated activation energy of the SML-QDs from temperature dependence is 30 meV.

• Journal of Powder Materials
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• v.1 no.1
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• pp.35-41
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• 1994

Mechanical alloying process of Al-8wt.% Ni powder was investigated for the various milling time in order to get the steady state powder. High temperature deformation behaviors of the sintered specimens were investigated by activation energy calculated after high temperature compression tests at the strain rates of 2.5$\times$10-3 s-1, 2.5$\times$10-2 s-1 and 2.5$\times$10-1 s-1 at the temperature range between $350^{\circ}C$ and $450^{\circ}C$. The steady state was obtained after 1000 minutes of milling with the PCA of 1.5 wt.% stearic acid under the condition of grinding media to powder weight ratio of 50 : 1 and impeller rotating speed of 300 rpm. True activation energy of Al-8wt.% Fe alloy was estimated to be 181 kJ/mole at the temperature range of 350~ $400^{\circ}C$ and 265 kJ/mole at the range of 400~$450^{\circ}C$.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.83-88
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• 2001

This study was preformed by measuring the minimum ignition temperature of MBS according to the change of sample vessel size and the minimum ignition temperature of MBS dust cloud The minimum ignition temperature of MBS product decreased as the vessel size was large, and it was obtained in the range from $120.5^{\circ}C$ to $94.5^{\circ}C$ and the apparent activation energy was obtained with 32.94Kcal/mol. The minimum ignition temperature of MBS dust cloud was measured by using Godbert-Greenwald furnace and it was obtained at $407^{\circ}C$ with the sample of 0.4g in the air and the ignition of dust cloud was not occurred below 13% oxygen concentration.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.261-267
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• 2006

Understanding the mechanism of carbon oxidation is important for the successful modeling of diesel particulate filter regeneration. Carbon oxidation characteristics were investigated by temperature programmed oxidation(TPO) method as well as constant temperature oxidation(CTO) with a flow reactor including porous bed. The activation energy of carbon oxidation was increasing with temperature and had two different constant values in the early and the later stage of the oxidation process respectively in TPO experiment. Kinetic constants were derived and the reaction mechanisms were assumed from the experimental results and a simple reaction scheme was proposed, which approximately predicted the overall oxidation process in TPO as well as CTO.