• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1201-1212
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• 1999

A numerical analysis is performed to predict the thermal response and ablation rate for charring or non-charring material which is designed to be used as thermal protection system (TPS). The numerical program composed of in-depth energy balance equation and the aerotherm chemical equilibrium (ACE) program. The ACE program calculates various thermochemical state from ablation products. The developed numerical program is verified by comparing the reported results from literature. The sensitivity tests for input parameters are performed. The thermal behavior of ablating material is mainly affected by density of ablating material, convective heat transfer coefficient and recovery enthalpy of flow field.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.20-27
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• 2003

In this paper, the fuel transport characteristics during transient condition was studied by using a Fast Response Flame Ionization Detector(FRFID). The quantitative measurement method for the inducted fuel mass into cylinder is studied. The inducted fuel mass into the cylinder was estimated by using calculated air-fuel ratio by hydrocarbon concentration of cylinder and air flow model. In order to estimate the transportation of injected fuel from the intake port into cylinder, the wall wetting fuel model was used. The two coefficient $\alpha$,$\beta$) of the wall-wetting fuel model was determined from the measured fuel mass that was inducted into the cylinder at the first cycle after injection cut-off To reduce an air/fuel ratio fluctuation during rapid throttle opening, the appropriate fuel injection rate was obtain from the wall wetting model with empirical coefficients. Result of air/fuel ratio control, air/fuel excursion was reduced.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.62-69
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• 2000

Present study deals with performance analysis of an inert gas generator (IGG) which can be used as effective means to suppress fire. The IGG uses a turbo-jet engine to generate inert gas for fire extinguishing. It is generally known that a less degree of oxygen content in the product of combustion will increase the effectiveness of fire extinguishing. An inert gas generator system with water injection has advantages of suffocating and cooling effects that are very important factors for fire extinguishing. Some aspects of influencing parameters, such as, air excess coefficient, compressor pressure ratio, air temperature before combustion chamber, gas temperature after combustion chamber, mass flow rate of water injection etc. on the performance of IGG system are investigated.

• Journal of Biomedical Engineering Research
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• v.3 no.1
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• pp.3-8
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• 1982

Solute transfer in artificial kidney dialyzers was analyzed using Kedem-Katcha- Isky's description on membrane transport. Mass transfer coefficient, K was deduced from the diffusive clearance of commercial hemodialyzers. It can to seen that Kd increases with the increase of blood flow rate, which means that there is substantial resistance in the blood phase for solute transport. Total clearance was estimated with the Werynski's formula. The increase in total clearance due to ultrafiltration was most significant for middle molecules like vitamin Bla, however that for smaller molecules such as urea and creatinine was minimal.

• Elastomers and Composites
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• v.24 no.2
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• pp.105-109
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• 1989

Liquid phase adsorption of organic compounds solution on the activated carbon fiber was measured by chromatographic method in a packed column. Adsorption equilibrium constant Ka of dextrose solution was found to be $72.5cm^3/g$ on ACF without bacteria growth, while in the bacterial ACF packed column Ka was $87.9cm^3/g$. It is suggested that for biological ACF there is a large contribution of bacterial activity to the adsorption equilibrium constant. Axial dispersion coefficient Ez was determined to be in proportional to flow rate and Pe=dpu/Ez independent or existence or bacteria.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.6
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• pp.655-667
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• 2017

The results of a numerical study on the performance of a propeller operating near a free surface are presented. The numerical simulations were performed for the various advance coefficients and the submergence depths of the model propeller. The effects of the model propeller size were investigated using two different model propeller sizes for all cases. The wave pattern of the free surface and the flow structure around the propeller as well as the hydrodynamic characteristics of the propeller were investigated through simulation results. The thrust and torque fluctuated and the trajectory of the tip vortex was distorted due to the interaction with the free surface. The wave pattern of the free surface was related to the tip vortex of the propeller. The decreases in thrust and torque at the small model propeller were greater than those of the large model propeller. The reduction rate of the thrust and torque increased with the advance coefficient.

• Tribology and Lubricants
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• v.19 no.6
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• pp.349-356
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• 2003

A damper floating ring seal with round hole pattern surfaces is suggested for better leakage control. The flat plate test of the round hole pattern surfaces has been performed to yield an empirical friction factor model. The exact predictions of the lock­up position of the damper floating ring, the leakage performance, and the rotordynamic coefficients of the seal are necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations including the empirical friction factor model for round hole pattern surfaces are solved by the Fast Fourier Transform method. The lock­up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the damper floating ring seal. Theoretical results show that the damper floating ring seals yield less leakage and better rotordynamic stability than the floating ring seal with a smooth surface.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.38-44
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• 2002

An experimental investigation was performed to observe the cooling performance of cutting oil and the effect of inclination angle on the transport behaviour of a inclined thermosyphons with low integral-fins. Relatively high rates of heat transfer have been achieved by operating this manner. Water has been used as the working fluid. The inclimation angle of thermoryphon and the ratio of Reynolds number of cooling to hot fluid have been used as the experimental parameters. Heat transfer coefficients at the condenser and the evaporator are estimated from experimental results. The experimental results have been assessed and compared with existing theory. Good agreement with the theory of Yiwei has been found. The maximum heat flow rate in the thermosyphon proved to depend upon the inclination angle.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.368-373
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• 1996

A simple set of the transition criterion of the condensation regimes and the heat transfer coefficients on the direct contact condensation of the core makeup tank is developed, and implemented in RELAP5/MOD3.1 The condensation regimes are divided into two regimes: supply limit and condensation limit. In mode]ing the transition criterion between two regimes, a large-eddy model developed by Theofanous is used, and the empirical coefficient of the present large-eddy model is close to that of the large-eddy model. It turns out that the modified code better predicts the experimental data, especially the injection flow rate and the water level trend than the original code does.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.701-707
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• 2007

The information on the incoming load to wastewater treatment plants is not often available to apply to evaluate effects of control actions on the field plant. In this study, a time series model was developed to forecast influent flow rate, BOD, COD, SS, TN and TP concentrations using field operating data. The developed time series model could predict 1 day ahead forecasting results accurately. The coefficient of determination between measured data and 1 day ahead forecasting results has a range from 0.8898 to 0.9971. So, the corelation is relatively high. We made forecasting program based on the time series model developed and hope that the program will assist the operators in the stable operation in wastewater treatment plants.