• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.152-158
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• 2004

Hydrogen has been considered as an important and essential future energy source. But the storage of the hydrogen is a difficult problem and many studies were focused on this matter. However, the MTH-system (methylcyclohexane, toluene, hydrogen) was proposed for storage of hydrogen by Taube et al. and that is the reaction of hydrogen with toluene to give methylcyclohexane. One toluene molecule can store six hydrogen atoms to form methylcyclohexane. In this form the hydrogen can be easily stored in liquid organic hydrides and transported at ambient pressure in tanks. Hence, this study is focused on the catalytic dehydrogenation of methylcyclohexane. Since supported platinum and nickel were employed as catalysts in literature, in this study, porous Pt and Ni were prepared and tested for the dehydrogenation reaction. When the porous Pt catalyst was applied to the dehydrogenation it showed higher activity in the reaction and higher selectivity to toluene. Specially at higher pressure, it showed almost 100 % conversion and 100 % selectivity and hence porous platinum could be considered as best for the given reaction.

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.140-146
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• 2006

The objective of this work is to analyze the atomization and evaporation characteristics of dimethyl ether(DME) fuel for the application of HCCI diesel engine. In order to investigate the spray behavior of DME fuel, the macroscopic and microscopic characteristics were investigated in terms of spray development, spray tip penetration, impingement time, SMD, and axial mean velocity under the various injection timing and ambient conditions. For the illumination of spray, the spray visualization system was composed of a Nd:YAG laser and an ICCD camera and laser-sheet method was used. The atomization characteristics of DME fuel are analyzed by using phase Doppler particle analyzer (PDPA) system It was reveal that the spray development of DME is slower and rapidly disappeared as elapsed time after start of injection at the same injection duration. The impingement timing of diesel fuel was fester than that of DME fuel. The comparison of spray atomization characteristics in both fuels shows that diesel fuel has a large SMD value that DME.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.1
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• pp.47-52
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• 1990

During prolonged exposure to the sun for 8 h each day for 10 days in which the highest ambient temperature around 14:00 h was $39^{\circ}C$, buffaloes exposed to the sun without shade increased the turnover of body water by 35% and 76% on day 5 and day 10 of exposure respectively. The total body water markedly decreased on day five and this amount was maintained thereafter. Plasma and blood volumes did not change significantly on day five but markedly decreased on day 10. Packed cell volume significantly decreased on day five and day 10 of the exposure period. The reduction of packed cell volume on day 10 coincided with the decrease in total plasma water. On day 10 of the exposure, an increase in the rate of liquid flow from the rumen was noted. It is concluded that on the fifth day of exposure, the increase in the evaporative cooling process was attributed to initial mobilization of water from the intracellular compartment. The reduction of both plasma and cell volumes occurring from day five to day 10 indicated a loss of body water from both intracellular and extracellular compartments.

• Progress in Superconductivity and Cryogenics
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• v.14 no.3
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• pp.38-42
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• 2012

Fixtures such as bushings in terminations of high temperature superconducting(HTS) power cable systems are subjected to high voltages, which have to transition from ambient to cryogenic temperatures. As such it is imperative to ensure the integrity of the dielectrics under all operating conditions, including thermal aspects brought about by the passage of current. Gaseous helium(GHe) at high pressure is regarded as a potential coolant for superconducting cables. The dielectric aspects of cryogenic helium gas are both complex and demanding. In this experimental study we looked at the interface between a smooth epoxy surface and high pressure helium gas in a homogeneous electric field. The alternating current(AC) flashover voltages of epoxy samples are presented. The results have been analyzed by using Weibull statistics. In addition to the behavior of the epoxy in gaseous helium as a function of pressure and temperature we also present data of the characteristics of the epoxy in mineral oil and in liquid nitrogen($LN_2$). The breakdown characteristics of a uniform field gap in gaseous helium as a function of pressure and temperature under AC, direct current(DC) and lightning impulse voltages are also given. Electric field calculations have been made for one of the experimental geometries in an attempt to explain some of the anomalies in the experimental results.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.59.1-59.1
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• 2012

Organic thin-film transistors (OTFTs) with printable semiconductors are promising candidate devices for flexible active-matrix (AM) display applications. Yet, stable operation of actual display panels driven by OTFTs has seldom been reported up to date. Here, we demonstrate a flexible reflective type polymer dispersed liquid crystal (PDLC) display, in which inkjet-printed OTFT arrays are used as driving elements with excellent areal uniformity in terms of device performance. As the active semiconductor, a novel, ambient processable conjugated copolymer was synthesized. The stability of the devices with respect to electrical bias stress was improved by applying a channel-passivation layer, which suppresses the environmental effects and hence reduces the density of trap states at the channel/dielectric interface. The combination of high performance and high stability OTFT devices enabled the successful realization of stable operating flexible color-displays by inkjet-printing.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.451-451
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• 2011

적외선 소자의 재료로 쓰이는 액상 에피 성장법(Liquid phase epitaxy: LPE)으로 성장된 HgCdTe (MCT)박막의 Hg 분위기 열처리에 따른 구조적 변화를 고 분해능 투과 전자 현미경으로 관찰하였다. 일반적으로 LPE방법으로 성장된 MCT박막은 성장 방법의 특성상 Te 과다 영역의 성장용액이 사용되므로 상온 냉각 과정에서 박막 내 국부적인 Te 석출물을 형성 시킬 가능성이 높다. 또한, 성장 과정시 높은 Hg 증기압으로 인해 Hg-vacancy가 존재하므로 품질을 저하시키는 요인이 된다. 따라서, 본 실험에서는 Hg-vacancy와 국부적인 Te 석출물의 제거를 위해 Hg 분위기 열처리 공정을 실시하여 박막의 결정성 변화 및 국부적인 조성 변화를 관찰하였다. 실험결과, 열처리에 따른 Hg의 박막 내 공급으로 인한 이차상의 형성 등이 관찰 되었으며 부피 팽창으로 인해 격자의 변형이 관찰 되었다. 이는 투과 전자 현미경의 고 분해능 이미지 와 Gaussian mask filtering 기법으로 보여진 격자 줄무늬상 (lattice fringe)으로 확인 하였다. 또한, 열처리에 따른 국부적인 조성 편기의 해소는 high angle annular dark field scanning TEM(HAADF-STEM)을 이용하여 관찰 하였다.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.147-156
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• 2000

In this study, the optimal operation parameters of MLE(Modified Ludzack-Ettinger) process treating the liquid supernatant separated from the slurry excreta of swine feedlot was studied as a promising biological treatment process. The nitrogen removal characteristics with different volume ratio between nitrification and denitrification reactor and the operational effect with different nitrogen loading rate, and different C/N($COD_{Cr}/TKN$) ratio were investigated. Based on the laboratory results, pilot MLE plant was operated to examine the effect of ambient temperature for five months including winter. The denitrification reactor which is 20% of total volume was proposed as the most optimal volume fraction for nitrification and denitrification. The optimum ratios of F/M and $F_N/M$ were increased with increase of the C/N ratio. However, optimum F/M ratio was changed more rapidly than $F_N/M$ ratio with increase of the C/N ratio. Therefore, MLE process is desirable to be controlled by F/M ratio in the range of high C/N ratio and by $F_N/M$ ratio in the range of low C/N ratio. Pilot MLE plant showed the higher removal efficiencies of COD and TKN in winter than in summer and was operated most stably at the temperature of $20{\sim}25^{\circ}C$ for mixed liqour.

• Aerospace Engineering and Technology
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• v.5 no.2
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• pp.174-180
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• 2006

The present paper describes transient thermal and mechanical analyses of a lox/kerosene type turbopump in a LRE(Liquid Rocket Engine). Turbopumps are used to pressurize propellants to achieve higher specific impulse of LRE. The turbopump under development has been designed and verified by structural analyses using finite element methods. Some parts of the turbopump operate under cryogenic environments, while the others work under ambient and high temperature environments. Therefore, numerical analysis at a turbopump system level is essential. In this study, casing assemblies of lox pump and fuel pump were analyzed to determine strength test and air-tightness test conditions. Also, some operational stress and strains of fuel pump casings were measured and analyzed. Based on these results, stress concentration of fuel pump casings during the operation could be successfully predicted.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.5-8
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• 2010

The GCSC injectors studied in this paper are those applied to the combustion chamber of staged combustion engines. Liquid fuel is injected through tangential holes along the outer wall of the GCSC injector forming a swirling sheet and oxygen rich gas generated by a preburner enters axially through the center orifice of the injector to form a gaseous jet. The spray characteristics of GCSC injectors under ambient/high pressure conditions and the effect of recess on spray characteristics have been examined in this paper. These results are expected to be used as fundamental data to develop of a staged combustion engine.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.61-65
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• 2011

Recently, LCD (liquid crystal display) industry is needed to goods of high reliability and wide range temperature condition and it is interested in products for extremely cold condition without failure of light-up. In this experiment, we made the LED backlight unit for Automotive-navigation under the extremely cold condition. And for making this backlight unit, we used to eight side emitting type white LEDs with 3W high power LED. We could know that this backlight unit releases to 18,000 nit in 24W power consumption and start up voltage time is under the 1ms in the ambient temperature at -40.