• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.346-349
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• 2002

High Power and high dose ion implantation is essentially needed to make power MOSFET devices based on SiC wafers, because the diffusivities of the impurities such as Al, N, p, B in SiC crystal are very low. In addition, it is needed high temperature annealing for electrical activation of the implanted species. Due to the very high annealing temperature, the surface morphology after electrical activation annealing becomes very rough. We have found the different surface morphologies between implanted and unimplanted region. The unimplanted region showed smoother surface morphology It implies that the damage induced by high energy ion implantation affects the roughening mechanism. Some parts of Si-C bonding are broken in the damaged layer, s\ulcorner the surface migration and sublimation become easy. Therefore the macrostep formation will be promoted. N-type 4H-SiC wafers, which were Al ion implanted at acceleration energy ranged from 30kev to 360kev, were activated at 1600$^{\circ}C$ for 30min. The pre-activation annealing for damage relaxation was performed at 1100-1500$^{\circ}C$ for 30min. The surface morphologies of pre-activation annealed and activation annealed were characterized by atomic force microscopy(AFM).

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.2
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• pp.48-54
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• 2003

To evaluate the radiation degradation of ethylene propylene rubber (EPR), radiation effects on EPR were investigated by using dielectric analysis and thermal-gravimetric analysis. Permittivity, loss factor, tan$\delta$, and thermal decomposition temperature were observed for ${\gamma}$-ray irradiated EPR. As the radiation dose was increased, the peak temperature of the loss factor and tans of EPR were increased and loss factor and tan$\delta$ at peak temperature were decreased. Activation energies were calculated using loss factor and thermal decomposition for ${\gamma}$-ray irradiated EPR as well. The trends of both calculated activation energies showed the same tendencies as radiation dose was increased.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.347-353
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• 2009

The apparent activation energy, the applied stress exponent, and rupture life have been measured from creep experiments over the range of $200^{\circ}C$ to $220^{\circ}C$ and the applied stress range of 64MPa to 94MPa. The materials were used AZ31 magnesium alloys treated by plasma electrolytic oxidation of $20{\mu}m$ and $40{\mu}m$ at surface to investigate the its influence on creep behavior, and creep tests were carried out under constant applied stress and temperature. The experimental results showed that the dipper the thickness of surface treatment the higher the activation energy and stress exponent. And the higher temperature and applied stress, the lower stress exponent and activation energy, respectively. Also the dipper the thickness of surface treatment the longer creep rupture time.

• Carbon letters
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• v.16 no.2
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• pp.127-131
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• 2015

In this work, highly porous carbons were prepared by chemical activation of carbonized biomass-derived aerogels. These aerogels were synthesized from watermelon flesh using a hydrothermal reaction. After carbonization, chemical activation was conducted using potassium hydroxide to enhance the specific surface area and microporosity. The micro-structural properties and morphologies were measured by X-ray diffraction and scanning electron microscopy, respectively. The specific surface area and microporosity were investigated by $N_2$/77 K adsorption-desorption isotherms using the Brunauer-Emmett-Teller method and Barrett-Joyner-Halenda equation, respectively. Hydrogen storage capacity was dependent on the activation temperature. The highest capacity of 2.7 wt% at 77 K and 1 bar was obtained with an activation temperature of $900^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.140-140
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• 2010

Non-mass analyzed ion shower doping (ISD) technique with a bucket-type ion source or mass-analyzed ion implantation with a ribbon beam-type has been used for source/drain doping, for LDD (lightly-doped-drain) formation, and for channel doping in fabrication of low-temperature poly-Si thin-film transistors (LTPS-TFT's). We reported an abnormal activation behavior in boron doped poly-Si where reverse annealing, the loss of electrically active boron concentration, was found in the temperature ranges between $400^{\circ}C$ and $650^{\circ}C$ using isochronal furnace annealing. We also reported reverse annealing behavior of sequential lateral solidification (SLS) poly-Si using isothermal rapid thermal annealing (RTA). We report here the importance of implantation conditions on the dopant activation. Through-doping conditions with higher energies and doses were intentionally chosen to understand reverse annealing behavior. We observed that the implantation condition plays a critical role on dopant activation. We found a certain implantation condition with which the sheet resistance is not changed at all upon activation annealing.

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.721-724
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• 2003

A Fe-Si-B-Ni amorphous alloy manufactured by one roll melt-spinning method showed the crystallization temperature difference of a maximum $10^{\circ}C$ according to each lot. This temperature difference had a considerable influence on the annealing process to be conducted for obtaining the proper inductance of the alloy. The proper annealing temperature of the alloy was $480^{\circ}C$ and the annealing time increased as the crystallization temperature increased. The activation energy measured by Kissinger method increased as the crystallization temperature increased. Therefore, the annealing process must be adjusted by the crystallization temperature difference of the amorphous alloy.

• Fire Science and Engineering
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• v.34 no.4
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• pp.45-51
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• 2020

The aim of this study is to investigate the gas temperature and velocity during sprinkler activation considering the fire growth scenario based on the thermal response model of the sprinkler. The fire source is assumed to have time square fire growth scenarios with a maximum heat release rate of 3 MW. Eight types of standard and fast-response sprinkler heads with an operating temperature range of 65-105 ℃ and a response time index range of 25-171 m^1/2s^1/2 were adopted. The temperature difference between the gas stream and the sensing element of the sprinkler head decreased as the fire growth slowed down, and the RTI value decreased. The overall gas temperature and velocity conditions predicted using the FDS model at sprinkler activation were in reasonable agreement with those of standard test conditions of the sprinkler head response. However, the sprinkler head could be activated at lower limits of gas temperature and velocity under the current test conditions for a slowly growing fire scenario.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.13-17
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• 2004

The effects of temperature on nitrification of enriched nitrifiers were investigated by using kinetics and thermodynamics method through the batch test. Aquaculture recirculating water, which was sampled at Chung Cheong Buk-Do Inland Fisheries Research Institute, was analized to observe the characteristics of nitrification. Temporal variation of ammonium, nitrite and nitrate concentration was measured at batch experiments. Activation energy was calculated using Arrhenius equation with the oxidation rates of specific ammonium or nitrite ion. These oxidation rates were measured at temperature range of $6-35^{\circ}C$ and ammonium concentration range of 0.2-1.8 mg/L. Two distinct activation energy of Nitrosomonas sp. at temperature $6-15^{\circ}C\;and\;15-35^{\circ}C$ was 93.1 and 25.0 KJ/mol, respectively. Nitrate accumulation was observed at temperature over $15^{\circ}C.$

• Transactions of Materials Processing
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• v.17 no.8
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• pp.558-563
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• 2008

The initial strain, the applied stress exponent, the activation energy, and rupture time in AZ31 magnesium alloy have been measured in order to predict the deformation mechanism and rupture life of creep over the temperature range of 423-443K. Creep tests were carried out under constant applied stress and temperature, and the lever type tester and automatic temperature controller was used for it, respectively. The experimental results showed that the applied stress exponent was about 9.74, and the activation energy for creep, 113.6KJ/mol was less than that of the self diffusion of Mg alloy including aluminum. From the results, the mechanism for creep deformation seems to be controlled by cross slip at the temperature range of 423-443K. Also the higher the applied stress and temperature, the higher the initial strain. And the rupture time for creep decreased as quadratic function with increasing the initial strain in double logarithmic axis.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.55-62
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• 2009

After examining the characteristics of the heat decomposition of the 80~120mesh flour using the Mini cup pressure vessel test and determining the apparent activation energy in a spontaneous combustion, the conclusion is as follows. The heat decomposition of flour occurs at around $100^{\circ}C$ and the peak for the maximum rise in pressure appears at around $290^{\circ}C$. The decomposition pressure against various temperature in the vessel shows the maximum value of $4.7kg/cm^2$ approximately at $440^{\circ}C$. When the thickness of the sample is 3cm, the maximum temperature and the critical temperature of ignition are $398^{\circ}C$ and $204.5^{\circ}C$, respectively; the critical temperature is $194.5^{\circ}C$ when the thickness of the sample is 5cm, and $182.5^{\circ}C$ when the sample is 7cm. In addition, the apparent velocity calculated using the method of least squares is 35.0407Kcal/mol.