• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1359-1365
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• 2014

In this study, 1-way fluid structure interaction analysis(FSI) for the shutter, component of side jet thruster was performed to evaluate the safety. Driving torque to open nozzle, thermal and high pressure load of hot gas was applied to shutter. Thus, the shutter must be designed to endure this load during combustion. We carried out computational fluid dynamics analysis to obtain the pressure, temperature, and heat transfer coefficient of hot gas of side jet thruster. We then used the data as the load condition for a thermal structural analysis using a mapping method. The locations with the maximum stress and temperature distributions were found. We compared the maximum stress with the tensile stress of shutter material according to temperature to evaluate the safety. We also analyzed the radial deformation of the shutter to set the proper interface gap with the side jet thruster parts.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.32-38
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• 2004

A comprehensive understanding is given for the hot-firing test results, which were obtained throughout the verification program of mono-propellant hydrazine rocket engines (thrusters) producing 0.95 lbf (4.2 N) of nominal steady-state thrust at an inlet pressure of 350 psia (2.41 Mpa). A scrutiny for the engine performance is made in terms of thrust and temperature behavior of steady state firing mode at the given propellant injection pressures: Pinj = 400, 250, 100, and 50 psi. The thrust and specific impulse are compared with a reference performance of 1-lbf standard rocket engines and their normalization procedure is introduced. A practical engineering approach to the data measurement and reduction is addressed, too.

• Bulletin of the Korean Space Science Society
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• 2006.04a
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• pp.96-96
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• 2006

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.72-78
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• 2005

We conducted the performance test of micronozzle having nozzle throat diameter of 1.0, 0.5, 0.25 mm in an ambient pressure. We used N2 gas as a cold gas propellant. We varied chamber pressure from 2 to 20 bar and measured the thrust and mass flow rate. Through the test, we concluded that viscous losses were increased with decreasing chamber pressure. We found that micronozzle performance was higher than orifice performance through thrust comparison.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.364-367
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• 2011

The development of the DCS thrust unit during the attitude control thruster of the launch vehicle and guided missile is introduced. The DCS thrust unit using solid propellants based on a two-axis control is designed and through the thermo-structural and flow analysis is designed in detail. The performance of the thrust unit based on the detail design is demonstrated through a combustion test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.791-797
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• 2018

In this work, the high-altitude environment simulation study was carried out at an altitude of 65 km exceeding Mach number of 6 after the launch of Korean Space Launch Vehicle using a shock tunnel. To minimize the flow disturbance due to the strut support of test model as much as possible, a few different types of strut configurations were considered. Using the configuration with minimum disturbance, the high-altitude environment simulation experiment including a propulsion system with a single-plume, was conducted. From the thruster test through flow visualization, not only a shockwave pattern, but a general flow-field pattern from the mutual interaction between the exhaust plume and the free-stream undisturbed flow, was experimentally observed. The comparison with the computation fluid dynamic(CFD) results, showed a good agreement in the forebody whereas in the afterbody and the nozzle the disagreement was about ${\pm}7%$ due to unwanted shockwave formation emanated from the nozzle-exit.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1399-1404
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• 2012

Because satellites operate in space, it is impossible to repair them when they malfunction. Therefore, to ensure the normal function of the payload used in the satellites, accurate assembly and installation of parts are crucial. To prevent abnormal functioning in the extreme environments during launch and in space, it is essential to test changes at the parts and system levels by performing alignment measurement before and after the launch environment test and the space environment test. Recently, noncontact three-dimensional precision machinery for medium- and large-sized parts has been developed. One of these is the theodolite measurement system, which is widely used in the aerospace industry. This study measures the angle of the dual thruster module that is used to control the attitude of KOMPSAT by using a theodolite, and alignment measurement and a reliability analysis are performed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.799-804
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• 2007

The behavior of spray emanating from an injector to be employed in a liquid-propellant thrust chamber is investigated by optical measurement techniques. The injector has eight holes, each of which has 30 cant angle from the center-axis with the diameter of 0.406 mm. In order to examine an atomization process according to the spray-generation conditions and the evolution along spray downstream, variational features in the velocity and size of droplets obtained through Dual-mode Phase Doppler An 799emometry (DPDA) are delineated and discussed together with instantaneous plane images captured by using Nd:Yag laser sheet beam. A categorization of spray-flow regime representing the atomization and turbulent nature is made through evaluating the non-dimensional parameters, i.e., Reynolds number and Weber number based upon the theoretical injection velocity. These qualitative and quantitative data of spray breakup will be a firm basis for the design of brand-new thruster

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1056-1062
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• 2008

The interaction between thrust plume and satellite base region was investigated by using direct simulate Monte-Carlo calculations. For the accurate simulation of N2 and H2 collisions and rotation-translation transition, a variable soft-sphere model and a recent rotational relaxation model of N2 and H2 were used. For the investigation of the interaction between thrust plume and base region, the number density distribution for each species, translational and rotational temperature distributions, heat flux, and pressure were examined by direct simulation of Monte-Carlo calculations. It was found that most of the surface properties are affected by H2 collisions and a strong non-equilibrium state is observed at the base region. It was demonstrated that an accurate model is needed to simulate H2 collisions and the rotation-translation transition. The results by the present calculation are more accurate than previous direct simulation Monte-Carlo calculations because more accurate rotational relaxation models were used in simulating the inelastic collisions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.838-842
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• 2017

The thruster valve, which is one of the key components applied to the mono-propellant system for the satellite, has a circular plate spring structure. It can be designed as a structure that does not have positional deformation and particles by friction and repetitive motion. In this study, finite element analysis and verification were performed by setting the width of the circular plate spring as a design parameter with the material, thickness and radius of the circular plate spring as fixed variables. The linearity of the spring constant is shown by the graph that is spring force with displacement. It is confirmed that the optimization design of the circular plate spring is possible by the spring force tendency according to the total area of circular plate spring.