• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.203-206
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• 2006

We have studied, for maximizing the total impulse of liquid propulsion system, Propellant Utilization System (PUS) to minimize outage of propellant. Propellant outage is mainly influenced by propellant mixture ratio during flight and real quantity of loaded propellant. If one employs cryogenic propellant, the variation of propellant density due to the temperature change has major effect on outage control. Feedback control of propellant level of each tank during flight could deplete both tanks simultaneously. To introduce this system, however, the mixture ratio control system of rocket engine is necessary.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.141-145
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• 2004

The residual propellant of satellite is the primary factor of satellite life. This propellant used in the satellite is stored as liquid in tanks. But it is very difficult to accurately measure propellant to be used for maintaining of satellite by an irregular influence of environment. In this paper, a new method of gauging propellant residual of satellite employing multi-tank system by measuring mass flow of thermal pumping liquid propellant is presented. In cases of being connected between tanks, propellant in tanks move by temperature difference of tanks. If propellant mass flow is measured at line between tanks, residual propellant in tanks is able to be estimated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.10
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• pp.1264-1270
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• 2004

In this paper research on micro solid propellant thruster is reported. Micro solid propellant thruster has four basic components; micro combustion chamber, micro nozzle, solid propellant and micro igniter. In this research igniter, solid propellant and combustion chamber are focused. Micro igniter was fabricated through typical micromachining and the effect of geometry was evaluated. The characteristic of solid propellant was investigated to observe burning characteristic and to obtain burning velocity. Change of thrust force and the amount of energy loss following scale down at micro combustion chamber were estimated by numerical simulation based on empirical data and through the calculation normalized specific impulses were compared to figure out the efficiency of combustion chamber.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.9-19
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• 2003

Nitrogen oxide gases which were produced by spontaneous reaction of nitrocellulose(NC) in the single base propellant accelerate the decomposition of propellant, and result in the reduction of shelf life. The amount of nitrogen oxide was reduced by the addition of 0.3wt% $CaCO_3$ to conventional stabilizer(DPA) and down of the solvent leaching temperature from $64^{\circ}C$ to $56^{\circ}C$, which extended the shelf life of the single base propellant as much as twice compare with commercial propellant. The perforation diameter increase of propellant from 0.64mm to 0.77mm could compensate for the drop of burning rate which was caused the addition of $CaCO_3$.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1280-1285
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• 2004

Microsystem technology has been applied to space technology and became one of the enabling technology by which low cost and high efficiency are achievable. Micro propulsion system is a key technology in the miniature satellite because micro satellite requires very small and precise thrust force for maneuvering and attitude control. In this paper research on micro solid propellant thruster is reported. Micro solid propellant thruster has four basic components; micro combustion chamber, micro nozzle, solid propellant and micro igniter. In this research igniter, solid propellant and combustion chamber are focused. Micro igniter was fabricated through typical micromachining and evaluated. The characteristic of solid propellant was investigated to observe burning characteristic and to obtain burning velocity. Change of thrust force and the amount of energy loss following scale down at micro combustion chamber were estimated by numerical simulation based on empirical data and through the calculation normalized specific impulses were compared to figure out the efficiency of combustion chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.79-82
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• 2004

Propellant feeding system is the system to satisfy propellant feeding requirements(mass flow rate, pressure, temperature) at engine inlet of launch vehicle. Propellant feeding test facility is being constructed for the development scheme of pressurization system, processing in tank, propellant piping system, and flow control system that are main technologies in order to develope propellant feeding system. This paper introduces the propellant feeding test facility being constructed in KARI.

• Journal of Applied Reliability
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• v.5 no.3
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• pp.357-371
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• 2005

Nitrogen oxide gases which were produced by spontaneous reaction of nitrocellulose (NC) in the single base propellant accelerate the decomposition of propellant, and result in the reduction of shelf life, The amount of nitrogen oxide was reduced by the addition of $0.3wt\%$ CaCO3 to conventional stabilizer(DPA) which extended the shelf life of the single base propellant as much as twice compared with commercial propellant.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.34-42
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• 2007

Ultrasonic inspection method is more profitable than X-ray radiographic inspection in cost and effect of defect detection such as debond, damage, and it doesn't need special constructions. The method can also be a possible real time inspection with safety. This report explains 1)the experiment and analysis of ultrasonic property of solid propellant, 2)the inspection methods of propellant/liner debond by inside or outside inspection, and 3)the inspection methods of propellant microcrack by damage. From the results, it is possible to detect the defect of propellant/liner debond by inside or outside inspection. Futhermore, it can be possible to detect the propellant microcrack caused by damage using the ultrasonic attenuation.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.125-132
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• 2004

The radial slot configuration in the solid propellant grain is usually fabricated by the polyurethane foam slot former The foam cannot be easily removed from the solid propellant, some can remain in the slot. Analogue solid propellant rocket motors using polyurethane foam to shape the slot are static fired with the foam former still in place in the slot. The pressure increases at the slot part are measured and there are indications of the propellant cracks at the insulations above the slot. The pressure increase is produced at the beginning of the burning sequence as the foam will hinder the combustion gas of the burning propellant from flowing into the central bore. The pressure increase up to about 300psi is predicted for the motor tested and this pressure increase depends on the gap between the propellant and foam surfaces and remaining foam volume. This amount of pressure increase inside of the slot is estimated to cause the propellant crack. To prevent this pressure increase, minimizing the foam remainder in the slot and making sufficient chamfering at the comer of the slot entrance are suggested.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.870-877
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• 2014

Geostationary satellites undergo various orbital perturbations and this results in location change. Therefore, all the geostationary satellites use the thruster in order to control the location change. For this purpose, the suitable amount of liquid propellant is mounted and the amount of propellant is reduced as time goes by. This means that the lifetime of the satellite depends on the residual propellant amount. Therefore precise residual propellant gauging is very important for the mitigation of economic losses arised from premature removal of satellite from its orbit, satellites replacement planning, slot management and so on. In this paper, we introduce the propellant gauging methods used in the geostationary satellites and the propellant gauging method studied in the laboratory level.