• Proceedings of the Korean Vacuum Society Conference
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• 2004.02a
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• pp.90-90
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• 2004

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1211-1214
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• 2003

The film is prepared by electron cyclotron resonance chemical vapor deposition (ECRCVD) employing CH$_4$ and H$_2$ gases. It is deposited by the control of microwave plasma power, gas flow ratio, deposition pressure, and In-situ thermal treatment temperature. The structure of a-C:H (hydrogenated amorphous carbon) thin film is analysed by FT-IR spectroscopy. The fraction sp$^3$ versus sp$^2$ bonding is very important to clear up the surface and interrace of a-C:H film properties such as nano-scale friction behavior. The sp$^3$ versus sp$^2$ bonding of a-C:H thin film is dependent on the deposition conditions, therefore. nano-scale friction behavior is dependent on the deposition conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.145.4-145
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• 1998

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1674-1680
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• 2002

An experimental study was made of a large-scale vortical structure over a backward-facing step. The Reynolds number based on the step height was R $e_{H}$ =33,000. To recognize the large-scale vortex, three components of velocity were measured. The measurements were performed in the recirculation zone (x/H=4.0) and the reattachment zone(x/H=7.5). To measure the wall pressure fluctuations in a turbulent flow over a backward-facing step, a 32-channel microphone array was installed beneath the wall in the streamwise and spanwise directions. From the measured pressure field, the size of large-scale vortex was obtained. As a detailed study, a conditionally-averaging technique was employed to characterize the coherent structure of the large-scale vortex. To see the relationship between the flow field and the relevant spatial mode of the pressure field, the spatial box filtering (SBF) was examined. A cross-correlation between velocity and pressure fluctuations was performed to identify the structure and the length scale of the large-scale vortex.x.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.180-180
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.10a
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• pp.135-136
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1069-1070
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.835-836
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• 2007

• Corrosion Science and Technology
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• v.15 no.3
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• pp.125-128
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• 2016

The ASTM T92 steel was corroded at $600^{\circ}C$ and $800^{\circ}C$ at 1 atm of $N_2/3.1%H_2O/2.42%H_2S-mixed$ gas. The formed scales were thick and fragile. They consisted primarily of the outer FeS scale and the inner (FeS, $FeCr_2S_4$)-mixed scale containing a small amount of the $Cr_2O_3$ scale. This indicated that corrosion occurred mainly via sulfidation rather than oxidation due to the $H_2S$ gas. Since FeS was present throughout the whole scale, T92 steel was non-protective, displaying high corrosion rates.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.139-151
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• 2011

The sulfur-iodine (SI) thermochemical water splitting cycle is one of promising hydrogen production methods from water using high-temperature heat generated from a high temperature gas-cooled nuclear reactor (HTGR). The SI cycle consists of three main units, such as Bunsen reaction, HI decomposition, and $H_2SO_4$ decomposition. The feasibility of continuous operation of a series of subunits for $H_2SO_4$ decomposition was investigated with a bench-scale facility working at ambient pressure. It showed stable and reproducible $H_2SO_4$ decomposition by steadily producing $SO_2$ and $O_2$ corresponding to a capacity of 1 mol/h $H_2$ for 24 hrs.