• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.866-869
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• 2001

In this study, (Ba,Sr)TiO$_3$(BST) thin films were etched with a magnetically enhanced inductively coupled plasma(MEICP). Etching characteristics of BST thin films including etch rate and selectivity were evaluated as a function of the etching parameters such as gas mixing ratio, rf power, dc bias voltage and chamber pressure. The maximum etch rate of the BST films was 1700 $\AA$/min at Ar(90)/CF$_4$(10), 600 W/350 V and 5 mTorr. The selectivity of BST to PR was 0.6, 0.7, respectively. To analyze the composition of surface residue remaining after the etching, samples etched with different CF$_4$/Ar gas mixing ratio were investigated with X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). From the results of XPS and SIMS, there are chemical reaction between Ba, Sr, Ti and C, F radicals during the etching and remained on the surface.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.798-800
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• 1998

(Ba,Sr)$TiO_3$ thin films were etched with $Cl_2$/Ar gas mixing ratio in an inductively coupled plasma (ICP) by varying the etching parameter such as f power, do bias voltage, and chamber pressure. The etch rate was $560{\AA}/min$ under Cl_2/(Cl_2+Ar)$ gas mixing ratio of 0.2, rf power of 600 W, do bias voltage of 250 V, and chamber pressure of 5 mTorr, At this time, the selectivity of BST to Pt, $SiO_2$ was respectively 0.52, 0.43. The surface reaction of the etched (Ba,Sr)$TiO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS).

• Journal of the korean Society of Automotive Engineers
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• v.10 no.4
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• pp.75-84
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• 1988

The performance and emission for the 4-cylinder 4-cycle gasoline engine fueled with methanol is predicted in this paper. The model for all the processes is illustrated. It computes the gas pressure, gas temperature and the rate of formation of nitric oxide and carbon monoxide at each crank angle using basic energy equation and reaction kinetic mechanism. The results are obtained at different operating conditions encompassing changes in fuel-air equivalence ratio, engine speed, spark timing and compression ratio. The special characteristics of methanol such as high power output and nitric oxide emissions have been truthfully predicted by the model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.34-38
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• 1999

In this study, molybdenum thin films were etched with the various Cl$_2$/(Cl$_2$+SF$_{6}$) gas mixing ratio in an magnetically enhanced reactive ion etching(MERIE) by the etching parameter such as rf power of 185 watts, chamber pressure of 40 mTorr and B-field of 80 gauss. The etch rate was 150 nm/min under Cl$_2$/(Cl$_2$+SF$_{6}$) gas mixing ratio of 0.25. At this time, the selectivity of Mo to SiO$_2$, photoresist were respectively 0.94, 0.50. The surface reaction of the etched Mo thin films was investigated with X - ray photoelectron spectroscopy (XPS).PS).

• New & Renewable Energy
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• v.20 no.1
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• pp.126-134
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• 2024

Biogas, composed mainly of methane (CH₄) and carbon dioxide (CO₂), is a renewable gas that can serve as an alternative energy source. In this study, we developed a new microwave reformer and analyzed its reforming characteristics. We observed that higher temperatures of the microwave receptor led to increased reforming efficiency. By supplying appropriate amounts of methane and steam, we could prevent carbon generated from the thermal decomposition reaction of carbon dioxide from depositing on the catalytic active layer, thus avoiding the inhibition of catalytic activity. Hydrogen generation was enhanced when maintaining the biogas ratio and steam supply at adequate levels. Increasing the SiC ratio in the receptor improved the uniformity of temperature distribution and growth rate, resulting in higher conversion rates of the reforming process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.1040-1047
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• 1999

The characteristics of flame propagation in inert particle-laden $H_2$/Air premixed gas are numerically investigated on this study. The 2nd order TVD scheme is applied to numerical analysis of governing equations and multi-step chemical reaction model and detailed transport properties are sued to solve chemical reaction terms. Radiation heat transfer is computed by applying the finite volume method to a radiative transfer equation. The burning velocities against the mole fractions of hydrogen agree well with results performed by different workers. The inert particles play significant roles in the flame propagation on account of momentum and heat transfer between gas and particles. Gas temperature, pressure and flame propagation speed are decreased as the loading ratio of particle is increased. Also the products behind flame zone contain lots of water vapor whose absorption coefficient is much larger than that of unburned gas. Thus, the radiation effect of gas and particles must be considered simultaneously for the flame propagation in a mixture of $H_2$/Air and inert particles. As a result, it is founded that because the water vapor emits much radiation and this emitted radiation is released at boundaries as radiant heat loss as well as reabsorbed by gas and particles, flame propagation speed and flame structure are altered with radiation effect.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.356-362
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• 2023

The risk of climate change has been long acknowledged, and ongoing efforts to overcome this issue, within the shipping sector, with the international maritime organization playing a central role. Conducting research on characteristics of soot formation is crucial to control its occurrence within the combustion process. In this study, the laser extinction method and chemical reaction numerical analysis were employed to examine the alterations in the state of chemical species associated with flame temperature, flame visual, and soot formation by mixing nitrogen, an inert gas, in the counterflow diffusion flame based on ethylene gas. The findings of the study suggest that as the mixing ratio of nitrogen increased, both the flame temperature and soot volume fraction decreased. Additionally, the area in which soot particles were distributed also decreased, and the volume fraction decrease rate declined when the mixing ratio increased by more than 30%. The mole fraction of the chemical species involved in soot growth also decreased. the chemical species associated with the HACA reaction were affected by variations in the hydrocarbon fuel ratio, and the chemical species related to the odd carbon path were confirmed to be affected by the flame temperature as well as the hydrocarbon fuel ratio.

• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.175-183
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• 1995

It is difficult to remove such interstitial impurities as sulfur, oxygen, hydrogen and carbon in Fe-Ni alloys. Thermodynamic and kinetic studies were carried out on the behavior of hydrogen gas, oxygen gas, Si, Al and slag, and the reaction time by the $Ar/Ar-H_2$ plasma and electron beam melting. After the addition of Al, Si, they were melted by Ar plasma with reaction time changed. 80%Ni-Fe alloys showed a better deoxidation than 36%Ni-Fe alloys. At $Ar-H_2$ plasma melting, the deoxidation was significant. In the case of the electron beam melting, the residual oxygen was higher than in Ar plasma melting because electron beam melting temperature was lower than that of Ar plasma. For the decaburization, it was melted by $Ar-O_2$ plasma melting, which could remove effectively carbon by activated oxygen in plasma. We added slag to Fe-Ni alloys for the desulfurization. As the result of this experiments, the amount of residual sulfur was not changed according to the slag ratio and reaction time.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.39-46
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• 2011

This study investigates the effects of the DME and n-Butane mixture and of the stratification on combustion characteristics of HCCI engine by chemical reaction calculation. First, the existing DME reaction scheme and n-Butane is combined to make new chemical reaction model, then validating the effectiveness of new scheme. Furthermore, this study verify the HCCI combustion characteristics according to the changes of DME and n-Butane mixture ratio, which shows different auto ignition characteristics. Finally, it confirms the effects of stratification of mixture fuel on the reduction of pressure rise rate.

• Tribology and Lubricants
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• v.25 no.1
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• pp.20-24
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• 2009

TiC-derived carbon coatings have been synthesized at $600^{\circ}C$ temperature treatment with $H_2/Cl_2$ mixture gases. From Raman spectroscopy measurements, the modified layer was covered with carbon and the thick-ness of the layer was increased with increasing reaction time. And $I_D/I_G$ ratio was decreased with increasing reaction time. The superior tribological property was obtained from TiC reacted with $Cl_2$ gas for 2 hrs. And the tribological property measurements indicate that TiC-derived carbon layer has $0.9{\times}10_{-6}mm^3/Nm$ in wear coefficient and 0.13 in friction coefficient.