• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
• /
• pp.159-164
• /
• 1997

Pyrolytic carbon layer was coated on A1203 balls by fluidized bed type chemical vapour deposition unit to develop the coating technology for the preparation of coated nuclear fuel. The deposition was carried out at the temperature ranges between 110$0^{\circ}C$ and 130$0^{\circ}C$ with various gas contents and flow rates. Source and carrier gas were propane and argon, respectively. X-ray analysis shows that the deposition layer was typical carbon spectra. The growth rate of carbon layer depended on the amount of source gas and the deposition temperature. For the alumina balls with 2mm in diameter, the deposition rate was 11${\mu}{\textrm}{m}$/hr in the flow gases containing 30% source gas at 130$0^{\circ}C$ with a total flow rate of 2.0$\ell$/min. Microstructural observation of the deposits with scanning electron microscope revealed that the deposits had relatively dense and isotropic structure. Chemical analysis by energy dispersive spectroscopy showed that the layer was pure carbon.

• 항공우주시스템공학회지
• /
• 제17권5호
• /
• pp.11-18
• /
• 2023

The architecture of the Fuel Thermal Management System (FTMS) in a commercial aircraft engine was built to model and simulate the fuel system. The study shows the thermal interactions between the fuel and engine lubrication oil through the mission profile of a high bypass ratio, two-spool turbofan engine. Fuel temperature was monitored as it flowed through each sub-component of the fuel system during the mission. The heat load in the fuel system strongly depended on the fuel flow rate, and was significantly increased for the periods of cruise and descent with decrease of fuel flow rate, rather than for the periods of take-off. Due to the thermal interaction in the pump housing, the fuel temperature at the outlet of the low-pressure pump was increased (4.0, 9.2, and 30.0) % over the case without thermal interaction for take-off, cruise, and descent, respectively.

• 한국환경보건학회지
• /
• 제28권5호
• /
• pp.93-101
• /
• 2002

We have studied that the prediction of desulfurization efficiency by limestone in fluidized-bed coal combustor. The results were presented as follows : Firstly, the bed temperature had a great deal of effect on the desulfurization and the optimum temperature of limestone was 85$0^{\circ}C$~90$0^{\circ}C$. Secondly, as the velocity and temperature increased, $K_{s}$, K and the desulfurization efficiency increased. So, $k_{s}$, $k_{d}$ highly depended on the air velocity and bed temperature, and $k_{s}$, $k_{d}$ were 82.53 mm/sec, 0.0041/sec at 0.2 m/sec, 85$0^{\circ}C$, $k_{s}$, $k_{d}$ were 125.62 mm/sec. 0.00532/sec at 0.3 m/sec, 80$0^{\circ}C$ respectively. And $k_{s}$, $k_{d}$ were 143.78 mm/sec, 0.00568/sec at 0.3 m/sec, 85$0^{\circ}C$. Thirdly, as a result of desulfurization modeling, there was good agreement between theory and experiments as anthracite fraction increased. At 3.0 of optimum Ca/S molar ratio, there was very good agreement between theory and experiments.riments.riments.s.

• 대한기계학회논문집A
• /
• 제31권12호
• /
• pp.1157-1164
• /
• 2007

Ceramic honeycomb structures have performed successfully as catalyst supports for meeting hydrocarbon, carbon monoxide and nitrous emissions standards for gasoline-powered vehicles. Three-way catalyst converter has to withstand high temperature and thermal stress due to pressure fluctuations and vibrations. Thermal stress constitutes a major portion of the total stress which the ceramic catalyst support experiences in service. In this study, temperature distribution was measured at ceramic catalyst supports. Thermal durability was evaluated by power series dynamic fatigue damage model. Radial temperature gradient was higher than axial temperature gradient. Thermal stresses depended on direction of elastic modulus. Axial stresses are higher than tangential stresses. Tangential and axial stresses remained below thermal fatigue threshold in all engine operation ranges.

• 한국응용과학기술학회지
• /
• 제17권2호
• /
• pp.132-138
• /
• 2000

Excess enthalpies ($H^{E}$) were measured by isothermal flow calorimetry for the nonionic amphiphile 2-butoxyethanol/water mixtures at 10 different temperatures (48.5 to $70^{\circ}C$) around and above the lower consolute solution temperature, $T_{lc}$. $H^{E}$ exhibits U-shape for the binary mixtures, and is large and negative which reflects substantial interaction between two chemical species. When the commonly used, semi-empirical Redlich-Kister (RK) polynomials were fitted to the measured $H^{E}$, plots of $H^{E}$ vs. weight fraction provided more accurate fitting with fewer parameters than conventionally drawn $H^{E}$ vs. mole fraction plots. This was due to the enhanced symmetry of $H^{E}$ vs. weight fraction plots. Using the fitted Redlich-Kister polynomials and the Gibbs-Helmholtz relation, temperature dependence of the activity coefficients were found and compared to the values determined from vapor-liquid equilibria. The activity coefficients were in the range of one to three, indicating that the binary system deviates from ideality but not substantially. They slightly depended on temperature and the temperature effect was equivalent to 10 % change in the activity coefficients.

• Structural Engineering and Mechanics
• /
• 제67권6호
• /
• pp.565-578
• /
• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

• 동력기계공학회지
• /
• 제19권6호
• /
• pp.68-74
• /
• 2015

NOx emission has been controlled because it is a major cause of the acid rain and effects considerably on formation and destruction of ozone. A SCR system on diesel engine is necessary to clear TierIII, because IMO(International Maritime Organization) plans on tightening regulations to TierIII at $1^{st}$ January 2016. In this study, flow analysis was accomplished with ANSYS Fluent program so that the SCR system would be retrofitted in training ship KAYA and the temperature distributions of exhaust gas in SCR sytem were investigated after it was installed. As a result, it was confirmed that pressure and velocity distributions in SCR system were depended on pipe line shapes, then it was designed as the pressure was lower. The temperature differential between 1 and 3 point was $15^{\circ}C$ because of evaporative latent heat of urea and the temperature of 4 point after catalyst was increased by $5^{\circ}C$ than 3 point because of exothermic reaction.

• 한국주조공학회지
• /
• 제23권5호
• /
• pp.268-275
• /
• 2003

The mechanism of the hydrogen gas pore formation was investigated in Lost Foam Casting of Al-alloy by reduced pressure test and real casting. The hydrogen gas pick-up was affected by the formed gas during the decomposition of polystyrene in addition to the liquid product. It depended on pouring temperature and a proper temperature of metal front gave the minimum hydrogen pick-up. At a low pouring temperature, the hydrogen went into the melt mainly from entrapped liquid product of polystyrene but pores were formed from the gas as well as the liquid product at a high pouring temperature. The mold flask evacuation down to 710torr decreased the gas porosity down by around 0.4% vol%. The entrapped decomposition product of polystyrene in the melt was observed through the visualization of filling behavior of Al alloy-melt with the high speed camera.

• 대한기계학회논문집A
• /
• 제28권4호
• /
• pp.333-342
• /
• 2004

Tensile and low cycle fatigue (LCF) tests on prior cold worked 316L stainless steel were carried out at various temperatures from room temperature to 650$^{\circ}C$. At all test temperatures, cold worked material showed the tendency of higher strength and lower ductility compared with those of solution treated material. The embrittlement of material occurred in the temperature region from 300$^{\circ}C$ to 600$^{\circ}C$ due to dynamic strain aging. Following initial cyclic hardening for a few cycles, cycling softening was observed to dominate until failure occurred during LCF deformation, and the cyclic softening behavior strongly depended on temperature and strain amplitude. Non-Masing behavior was observed at all test temperatures and hysteresis energy curve method was employed to describe the stress-strain hysteresis loops at half$.$life. The prediction shows a good agreement with the experimental results.

• Transactions on Electrical and Electronic Materials
• /
• 제1권4호
• /
• pp.25-29
• /
• 2000

In this paper, PET(Ployethylene Terephthalate) films with semiconducting and interface layers were investigated, The electrical properties, such as volume resistivity, tan$\delta$(dissipation factor) and breakdown strength at various temperatures were measured. Thermal analysis of PET and semiconducting films were measured and compared by differential scanning calorimeter(DSC) of each film. It is found that the volume resistivity of films(dependence on semiconducting interface layers)and electrical properties of PET films are changed ,Breakdown strength and dissipation factor of PET films with semiconducting layer (PET/S/PET) are decreased more greatly than PET and PET/PET films, due to the increase of charge density of charges at two contacted interfaces between PET and semiconductor, The dissipation factor of each films in increased with temperature,. For PET/S/PET film, is depended on temperature more than PET of PET/PET. However, the breakdown strength is increased up to 85$\^{C}$ and then decreased over 100$\^{C}$The electrical properties of PET films with semiconducting/interface layer are worse than without it It is due to a result of temperature dependency, which deeply affects thermal resistance property of PET film more than semiconducting/interface layers.