• Journal of ILASS-Korea
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• v.2 no.2
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• pp.43-50
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• 1997

The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

• Journal of Powder Materials
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• v.15 no.2
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• pp.87-94
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• 2008

In order to investigate a nitriding process of spent oxide fuel and the subsequent change in thermal properties after nitriding, simulated spent fuel powder was converted into a nitride pellet with simulated fission product elements through a carbothermic reduction process. Nitriding rate of simulated spent fuel was decreased with increasing of the amount of fission products. Contents of Ba and Sr in simulated spent fuel were decreased after the carbothermic reduction process. The thermal conductivity of the nitride pellet was decreased by an addition of fission product element but was higher than that of the oxide fuel containing fission product elements.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.123-126
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• 2011

A Fuel-rich preburner using kerosene fuel is operated in a non-equilibrium condition and a prediction of burnt-gas properties is not easy from a chemical equilibrium analysis. A premixed counter-flow flame analysis was conducted for the prediction of burnt-gas properties. JP10 was selected for a representative kerosene fuel and a non-equilibrium combustion analysis was accomplished in supercritical condition using UC San Diego reaction mechanism. The premixed counter-flow flame was assumed for stationary and stable flame, and the temperature result in present study was overestimated rather than the experimental results from Huzel. From the difference of the temperature result, other properties, heat capacity, specific heat ratio and molecular weight had some differences against the experimental results. Moreover, the present results was more similar to the experimental results than those of the equilibrium analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.88-92
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• 2003

The correlationship between heat treatment condition and electrical properties of the Mn-Co-Ni oxide NTC thermistor for fuel level sensor was investigated by the X-ray diffractometry, density measurement, and electrical properties measurement such as resistivity, B constant, and thermal dissipation constant. It was shown that the heat treatment of NTC thermistor was responsible for sinterability of Mn-Co-Ni oxide. The highest density of 5.10 g/㎤ was obtained at $1250^{\circ}C$, 2 hours, at which the densification was almost completed. This is also manifested from the microstructural observation. It is found that the electrical resistivity and B constant are increased at the elevated sintering temperatures. The NTC specimens prepared in this study showed the conventional decrease of resistance with the measured temperature and the linear behavior of output voltage with fuel levels. Therefore, the electrical properties of thermistor were closely correlated with sintering condition. and the Mn-Co-Ni oxide thermistor prepared in this study has a great possibility enough to apply for an automobile fuel level sensor.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.39-48
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• 2010

In order to investigate the effects of tempering temperature and heat-treatment path on the microstructural and mechanical properties of ASTM Gr.92 steels, four samples with different tempering temperatures and heat-treatment paths wer prepared. THeree experimental steels showed tempered martensitic microstructures, but the sample tempered at $810^{\circ}C$ was presumed to retain partially untempered martensitic microstructures due to a lower ${\alpha}$+${\gamma}$ phase regime. $M_{23}C_6$, V(C,N), and Nb(C,N) precipitates were observed in all samples. In addition $Cr_2N$ was observed to be precipitated finely and uniformly by isothermal heat-treatment. The lath width and precipitate size in the isothermal heat-treated samples were much smaller than those of the tempered-only specimens. Because of a fine and uniform precipitate, a reduction of lath width would enhance precipitation hardeing, and it was shown that mechanical propertiesincluding the hardness and tensile properties of the steels were improved by isothermal heat-treatment.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.409-418
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• 2008

Because the interaction layers that form between U-Mo particles and the Al matrix degrade the thermal properties of U-Mo/Al dispersion fuel, an investigation was undertaken of the undesirable feedback effect between an interaction layer growth and a centerline temperature increase for dispersion fuel. The radial temperature distribution due to interaction layer growth during irradiation was calculated iteratively in relation to changes in the volume fractions, the thermal conductivities of the constituents, and the oxide thickness with the burnup. The interaction layer growth, which is estimated on the basis of the temperature calculations, showed a reasonable agreement with the post-irradiation examination results of the U-Mo/Al dispersion fuel rods irradiated at the HANARO reactor. The U-Mo particle size was found to be a dominant factor that determined the fuel temperature during irradiation. Dispersion fuel with larger U-Mo particles revealed lower levels of both the interaction layer formation and the fuel temperature increase. The results confirm that the use of large U-Mo particles appears to be an effective way of mitigating the thermal degradation of U-Mo/Al dispersion fuel.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.10a
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• pp.193-194
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• 2016

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.914-921
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• 2010

Studies were carried out to assess the microstructural and mechanical properties of ferriticmartensitic steel under a flowing sodium environment. HT9 (12Cr-MoVW) and Gr.92 (9Cr-MoVNbW) steel were exposed to liquid sodium at $650^{\circ}C$ containing dissolved oxygen of 20 ppm for 2333 hours and evaluations of the microstructure as well as the mechanical properties of the microhardness and nanoindentation were carried out. The result showed that both HT9 and Gr.92 exhibited macroscopic weight loss caused by general corrosion as well as localized types such as intergranular corrosion and pitting. Decarburization at the steel surface took place as the test proceeded. As the Cr content increased, dissolution and decarburization were suppressed. Assessment of the actual cladding geometry revealed that an aging process rather than decarburization governed the mechanical properties, which resulted in a decrease of the microhardness and yield stress.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.91-91
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• 2010

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.275-281
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• 2007

GTL (Gas To Liquid) has the potential to be used in diesel engines as a clean alternative fuel due to advantages in emission reduction, particularly soot reduction. Since the physical properties of GTL fuel differ from those of diesel fuel to some extent, studying how this difference in characteristics of GTL and diesel fuels affects spray and combustion in diesel engines is important. In this study, visual investigation of sprays and flames from GTL and diesel fuels in a vessel simulating diesel combustion was implemented. The effects of various parameters and conditions, such as injection pressure, chamber temperature and pilot injection on liquid-phase fuel length and auto-ignition delay were investigated. It was determined that GTL has a somewhat shorter liquid-phase fuel length, which explains why there is less contact between the fuel liquid-phase and flame for GTL fuel compared to diesel fuel.