• Membrane Journal
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• v.20 no.2
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• pp.106-112
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• 2010

This study deals with the surface fluorination of poly(phenylene oxide) (PPO) with the direct contact of 100 ppm fluorine gas. To characterize the surface fluorinated membranes, the contac angle measurement, X-ray photoelectron microscopy analysis and the gas permeation experiments were performed. As the fluorination time increases, the hydrophobicity of membrane surfaces is increased by the surface characterization. In general, as expected, the overall gas permeability was reduced. Typically, the permeability reduction of 33% for nitrogen, 23% for oxygen and 3% for carbon dioxide were observed when the membranes were exposed in 100 ppm environment for 60 min., meanwhile the selectivity was increased from 3.92 to 4.47 for $O_2/N_2$ and 18.09 to 25.4 for $O_2/N_2$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.204-207
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• 2003

This paper presents the electrical properties of PTFE (polytetrafluoroethylene) nozzle for circuit breaker. PTFE has been used widely as a nozzle material for circuit breaker. In the arcing environment in a circuit breaker, radiation is considered to be the major energy transport mechanism from the arc to the wall. The fraction of the radiation power is emitted out of the arc and reaches the nozzle wall, causing ablation at the surface and in the depth of the wall. The energy concentration in the material lead to the depolymerization and eventually lead to the generation of decomposed gas as well as some isolated carbon particles. The generation of the decomposed gas in the depth of the material causes inner explosion. The surface of nozzle becomes uneven. The flow of gas is not uniform due to the unevenness of the surface. Adding some fillers into PTFE is expected to be efficient for improving the endurability against radiation. In this experiment, three kinds of fillers that have endurance in the high temperature environment were added into PTFE. Dielectric constant, dissipation factor, electrical resistivity and dielectric strength of PTFE composites were investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.696-696
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• 2013

Solid Oxide Fuel Cells (SOFCs) have been gaining academic/industrial attention due to the unique high efficiency and minimized pollution emission. SOFCs are an electrochemical system composed of dissimilar materials which operates at relatively high temperatures ranging from 800 to 1000oC. The cell performance is critically dependent on the inherent properties and integration processing of the constituents, a cathode, an electrolyte, an anode, and an interconnect in addition to the sealing materials. In particular, the gas transport, ion transport, and by-product removal also affect the cell performance, in terms of open cell voltages, and cell powers. In particular, the polarization of cathode materials is one of the main sources which affects the overall function in SOFCs. Up to now, there have been studies on the materials design and microstructure design of the component materials. The current work reports the effect of thin film processing on cathode polarization in solid oxide fuel cells. The polarization issues are discussed in terms of dc- and ac-based electrical characterizations. The potential of thin film processing to the applicability to SOFCs is discussed.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1727-1732
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• 2017

Pyroprocessing is an alternative method of reprocessing spent fuel, usually involving the dissolving spent fuel in a molten salt media. The National Nuclear Laboratory designed, built, and commissioned a molten salt dynamics rig to investigate the transfer characteristics of molten lithium chloride-potassium chloride eutectic salt. The efficacy and flow characteristics of a high-temperature centrifugal pump and argon gas lift were obtained for pumping the molten salt at temperatures up to $500^{\circ}C$. The rig design proved suitable on an industrial scale and transfer methods appropriate for use in future molten salt systems. Corrosion within the rig was managed, and melting techniques were optimized to reduce stresses on the rig. The results obtained improve the understanding of molten salt transport dynamics, materials, and engineering design issues and support the industrialization of molten salts pyroprocessing.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.67-73
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• 2011

One of the important topics to prepare the up-coming era of so-called ‘hydrogen economy’ is hydrogen transmission. Pipeline is conceivably the most economic way to consistently and safely transport a large amount of hydrogen over a long distance, which may be strongly requested in hydrogen economy era. As a good starting point for the purpose, one might wonder whether conventional API pipeline steels as designed for natural gas transmission can be used as the hydrogen pipeline materials or not. To answer the question, here we performed a series of micro-/nano-indentations together with tensile tests on the hydrogen-charged API X65, X70 and X100 steels having different strength level. In this paper, from the results of tensile tests, the hydrogen effects on the mechanical behavior in the API steels are systematically evaluated.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.234-234
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• 2011

Electron-neutral collision frequency is one of the important parameters in the plasma physics and in industrial plasma engineering. We can understand the momentum, energy, and charge transport properties of the plasma using electron-neutral collision frequency.[1] The wave-cutoff method is a diagnostic method for the electron density measurement, but the cutoff peak value depends on gas pressure. The wave-cutoff signal becomes unclear as increasing gas pressure. The reason of pressure dependence is that the electron-neutral collision disturbs electron motion so that microwave can propagate through plasma at plasma frequency.[2] Using the pressure dependence of wave-cutoff method we can find the electron-neutral collision frequency. At first we tried to confirm this method using well known gas such as Ar. The cutoff signal decrease as increasing gas pressure (the simulation result). The wave-cutoff signal is unclear at a gas pressure of 500 mTorr. (electron density $1.0{\times}10^{10}/cm^3$, electron temperature 1.7 eV, electron -neutral collision frequency~1 GHz). In this condition, the electron-neutral collision frequency is closed to the wave-cutoff frequency.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.199-207
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• 2015

Solid materials of ammonia sources with SCR have been considered for the application of lean NOx reduction in automobile industry, to overcome complex problems of liquid urea based SCR. These solid materials produce ammonia gas directly with proper heating and can be packaged by compact size, because of high volumetric ammonia density. Among ammonium salts and metal ammine chlorides, calcium ammine chloride was focused on this paper due to low decomposition temperature. In order to make calcium ammine chloride in lab-scale, simple reactor and glove box was designed and built with ammonium gas tank, regulator, and sensors. Basic test conditions of charging ammonia gas to anhydrous calcium chloride are chosen from equilibrium vapor pressure by Van't Hoff plot based on thermodynamic properties of materials. Synthetic method of calcium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%) from simple weight calculations which were confirmed by IC. Also, lab-made calcium ammine chloride were analyzed by TGA and DSC to clarify decomposition step in the equations of chemical reaction. To understand material characteristics for lab-made calcium ammine chloride, DA, XRD and FT-IR analysis were performed with published data of literature. From analytical results, water content in lab-made calcium ammine chloride can be discovered and new test procedures of water removal were proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.536-542
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• 2018

Tin dioxide, $SnO_2$, is a well-known n-type semiconductor that shows change in resistance in the presence of gas molecules, such as $H_2$, CO, and $CO_2$. Considerable research has been done on $SnO_2$ semiconductors for gas sensor applications due to their noble property. The nanomaterials exhibit a high surface to volume ratio, which means it has an advantage in the sensing of gas molecules. In this study, SnO nanoplatelets were grown densely on Si substrates using a thermal CVD process. The SnO nanostructures grown by the vapor transport method were post annealed to a $SnO_2$ phase by thermal CVD in an oxygen atmosphere at $830^{\circ}C$ and $1030^{\circ}C$. The pressure of the furnace chamber was maintained at 4.2 Torr. The crystallographic properties of the post-annealed SnO nanostructures were investigated by Raman spectroscopy and XRD. The change in morphology was confirmed by scanning electron microscopy. As a result, the SnO nanostructures were transformed to a $SnO_2$ phase by a post-annealing process.

• Journal of the Korea Convergence Society
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• v.6 no.3
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• pp.13-18
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• 2015

This paper is the study on the safe design of joint controling the pressure and temperature by connecting between pipes laying with the flexible joint. This study aims at decreasing the excessive pressure applied in the pipe and preventing the accident occurrence in order to solve the pipe damage by extraction and contraction due to the pressure of open air and transport gas. The flow properties of each model are investigated through the simulation analysis by applying three kinds of the flexible joints. When transport gas passes the flexible joint, the flow characteristics of heat, pressure and velocity at pipe laying are analyzed. It is thought to be contributed to the safe design due to the shape of the flexible joint by using the result of this study. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.96-103
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• 1996

This paper describes the electron transport characteristics in SF6 gas calculated for range of E/N values from 150~ 800[Td) by the Monte Carlo simulation and Boltzmann equation method using a set of electron collision cross sections detennined by the authors and the values of electron swarm parameters are obtained by TOF method. The results gRined that the values of the electron swarm parameters such as the electron drift velocity, the electron ionization or Rttachment coefficients, longitudinal and transverse diffusion coefficients agree with the experimental and theoretical for a range of E/N. The properties of electron avalanches is concerned electron energy non--equilibrium region. The electron energy distributions function were analysed in sulphur hexafluoride at E/N : 500~800[Td) for a case of non-equilibrium region in the mean electron energy. The validity of the results obtained has been confilll1ed by a TOF method.