• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3154-3158
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• 2008

A liquid rocket engine performance has been analyzed as a function of combustion pressure with LOx/RP-1R. The present method is verified by comparing the specific impulse for various combustion pressure with given pump head model. The optimal combustion pressure is between 150 bar and 200 bar for given efficiencies. Both the optimal combustion pressure and the specific impulse increase for increased turbine efficiency. The optimal combustion pressure decreases and the specific impulse increases for increased combustion efficiency. The pump efficiency and the turbine inlet temperature have the same qualitative effect as the turbine efficiency.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.133-139
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• 2009

An analysis has been performed on the specific impulse for a liquid rocket engine of gas generator cycle. The present analysis method has been validated through the comparison of the optimal specific impulse for the 300t thrust conceptual engine against the published data. The engine specific impulse can be increased by applying film coolant decreasing the fuel pump head for regenerative cooling despite the decrease of specific impulse of the combustion chamber when the film coolant participates combustion more than the critical amount. The improved condition shows that higher combustion chamber pressure is achieved with less fuel pump head rise by additional film cooling.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.93-97
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• 2010

The analysis of specific impulse of the liquid rocket engine employing gas generator cycle with LOx/kerosene as propellant has been performed. The relative error of performance of 300 ton level engine is 0.1%s for specific impulse and 12% for optimal combustion pressure comparing with the published data. The difference of the performance model and the material property models of gas generator product gas are the presumed major reason of discrepancy. The optimal condition of 30 ton level engine is combustion pressure of 68 bar and mixture ratio of 2.2 for maximum specific impulse. This optimal condition can be changed by performance models.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3518-3523
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• 2007

An analysis program of specific impulse has been developed for a gas generator cycle rocket engine. The program has been verified by comparing the published performance data of the same cycle engine with RP-1 as fuel. A model for pressure drop of regenerative cooling and film cooling mass flow rate has been suggested to satisfy the necessary cooling condition with Jet-A1 as fuel. The engine mixture ratio is defined by the film cooling mass flow rate and the core mixture ratio. The optimal condition of the combustor pressure and engine mixture ratio has been found for maximum specific impulse.

• International Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.11-16
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• 2019

A system analysis program has been developed for a gas generator cycle liquid rocket engine of 30 ton class. Numerical models have been proposed for a combustor, a turbopump, a gas generator and pressure drop through a regenerative cooling system. Numerical algorithm has been validated by comparing with the published data of MC-1. The major source of error is not the numerical algorithm but the imperfect performance models of subsystems. So the precision of the program can be improved by revising the performance models using experimental data. The sea level specific impulse and vacuum specific impulse have been demonstrated for a 30 ton class gas generator engine. The optimal condition of combustor pressure and mixture ratio for specific impulse which is a typical characteristic of a gas generator cycle engine has been illustrated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.135-140
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• 2007

An analysis has been conducted of the optimal condition to maximize the specific impulse for a liquid rocket engine with film cooling. The present engine performance has been compared with the published conceptual design to be verified satisfactorily accurate. The optimal combination of film coolant flow rate and the regenerative cooling capacity has been found for maximum specific impulse. The optimal fuel pump pressure increases and the optimal film coolant flow decreases for a larger thrust engine. Higher turbine inlet temperature increases both the fuel pump pressure and the film coolant flow rate as the optimal condition. The coking temperature has the same qualitative effect as the turbine inlet temperature.

• Culinary science and hospitality research
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• v.23 no.8
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• pp.27-39
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• 2017

This study was to examine how consumption value of female consumers affects impulse consumption and purchase satisfaction when they buy bakery goods, present specific determinant factors that affect them, and identify its influencing factors. The survey was conducted with those who have bought bakery goods of female consumers in Seoul and Kyonggi area, using a convenience sampling method. After a total of 400 responses was collected, 366 responses were included for the multiple regression analyses in order to test the hypotheses. To summarize findings from this study, analysis of the first hypothesis showed that "emotional impulse buying," "stimulating impulse buying," "reminder impulse buying," and "situational impulse buying" among impulse buying factors in consumption value factors had positive effects. The second hypothesis analyzed that "emotional impulse buying," "stimulating impulse buying," and "situational impulse buying" gave positive impacts on "purchase satisfaction," while "reminder impulse buying" had no influence. Analysis of the third hypothesis demonstrated that "consumption value" had positive effects on "purchase satisfaction." These findings were significant to examine consumption value that show the consuming pattern of consumers, analyze influencing factors on impulse buying of female consumers, and further present marketing strategies used for advantageous tools with competing stores to bakery owners or marketers.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.284-290
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• 2006

For the case of high head and critical low flow rate range of micro hydropower resources, it requires very low specific speed turbines which are lower than conventional impulse turbine's specific speed. In order to satisfy the request for very low specific speed turbine with high efficiency, a new positive displacement turbine is developed. The performance characteristics of the new turbine is tested and compared with a conventional impulse turbine, which is used for automatic water faucet system. The purpose of present study is to develop an high performance turbine that can be used to extract micro hydropower potential of a water supply system. The test results show that the positive displacement turbine is much more efficient than the conventional turbine and it can sustain high efficiency under the wide range of operating conditions. The pressure pulsations at the inlet and outlet of the positive displacement turbine can be considerably minimized by using simple pressure damper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.148-154
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• 2004

As a rocket propellent of hydrocarbon fuels, the characteristics of liquefied natural gas was evaluated with the viewpoint of the constituents and content, the cooling performance as a coolant, and characteristic velocity and specific impulse as parameters of the engine performance. Content of methane was a principal factor to determine the characteristics as a rocket propellant and more than 90 % of it was needed as a fuel and coolant in the regenerative cooled liquid rocket engine. Some constituents of the liquefied natural gas can be frozen by the pre-cooling of the pipe lines, therefore they can be a factor disturbing the normal working of engine. In case the content of methane is around 90% in the liquefied natural gas, a normalized stoichiometric O/F mixture ratio of 0.75 is suggested for a nominal operation condition to get the maximum specific impulse and characteristic velocity.

• Korea Trade Review
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• v.46 no.6
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• pp.163-190
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• 2021

The paper studies the impulse buying behavior of Chinese consumers during the online shopping festivals of the specific situations and their influencing factors with empirical analysis. We carried out an empirical analysis on 302 Chinese consumers with shopping experience in the online shopping festival. The study result shows that (1) marketing stimulation, preferential promotion and features of consumers have a significant positive influence on the impulse buying behavior; while the freight reduction has no significant influence on impulse buying behavior; (2) the perceived value has a significant positive influence on the Chinese consumers to have impulse buying behavior; (3) perceived value works as an in the relationship between the marketing stimulation, preferential promotion and features of consumers and the impulse buying behavior, but it has no meditating role between the freight reduction and the impulse buying behavior.