• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.9-15
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• 2012

This research simulates the ultrasonic wave propagation in multi-layered media using generalized formular of system response function. We made the artificial defect specimen of a rocket motor and compared with experimental wave forms. The simulation results are coincide with measured waves and we found that the pulse echo method is able to detect unbond defect at liner-propellant interface.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.429-435
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• 2015

This study proposes a re-adhesion algorithm that has stable traction effort for rolling stock slip/slide minimization when deliverable traction decreases by slip. The proposed scheme estimates appropriate reference speed using two encoders for reducing slip and controls traction effort stably and has stable control characteristics for disturbance. The algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force stably controls traction effort and gives rolling stock excellent acceleration and deceleration characteristics. And a slip sensing element that can quickly detect slip is used. Load motor and inverter were checked in various slip conditions for creating various line conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.53-56
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• 2005

Hybrid rocket had many advantage with compared to solid and liquid rockets. In this study, swirl flow hybrid motor was designed and manufactured. And the methods of regression rate improvement wire considered. Thrust was calculated with pressure of the combustion chamber and the regression rate was measured in low flow rate of oxidizer. Several problems and solutions of operating hybrid rocket was presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.3
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• pp.61-67
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• 2004

The extinction characteristics of the solid propellant were studied experimentally in this paper. These characteristics are required for designing TCO (thrust cut off) system of the solid rocket motor Parameters to characterize solid propellant extinction were defined by physical observation. A device was designed (or acquiring these parameters and the firing tests were implemented to get the preliminary data for the extinction characteristics of HTBP propellant.

• Journal of Power Electronics
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• v.8 no.1
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• pp.23-34
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• 2008

This paper deals with a Direct Torque Control (DTC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) for the Electric Vehicle (EV) propulsion system using a Neural Network (NN). The Conventional DTC with optimized switching lookup table and three level torque controller generates relatively large torque ripples in an electric vehicle motor drive. For reducing the torque ripples, a three level torque controller is hereby replaced by the five level torque controller. Furthermore, the switching lookup table of the five level torque controller based DTC is replaced with a Neural Network. These DTC schemes of an IPMSM drive are simulated using MATLAB/SIMULINK. The simulated results are compared with the conventional DTC and it is found that the ripples in the torque, as well as in the stator current, are reduced drastically.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.393-397
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• 2006

In this study, combustion characteristics of solid propellants using sorbitol and potassium nitrate were found out. Burning rate was calculated with several combustion experiments, also specific impulse and characteristic exhaust velocity were compared with theoretical value. Thrust measured with thrust measurement system using plate spring. Mixture ratio of propellants was varied in experiments, also combustion characteristics of solid propellants which consulted experimental results was used micro solid rocket design having 1mm nozzle throat.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.311-317
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• 2005

Hybrid rocket had many advantage with compared to solid and liquid rockets. In this study, swirl flow hybrid motor was designed and manufactured. And the methods of regression rate improvement were considered. Thrust was calculated with pressure of the combustion chamber and the regression rate was measured in low flow rate of oxidizer. Several problems and solutions of operating hybrid rocket was presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.912-918
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• 2011

This research simulates the ultrasonic wave propagation in multi-layered media using generalized formular of system response function. We made the artificial defect specimen of a rocket motor and compared with experimental wave forms. The simulation results are coinciede with mesuared waves and we found that the pulse echo method is able to detect disbond at liner-propellant interface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.332-335
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• 2011

Electro-Mechanical Ignition Safety Device(EMISD) for solid rocket motor is designed and manufactured. The EMISD utilizes a true rotary solenoid for arming mechanism and an electric squib(initiator) for generating ignition energy. In order to prove the ignition capability of the EMISD, 10-cc Closed Bomb Test(CBT) is performed, which measures the pressure built by high temperature and high pressure gas generated by operating EMISD.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.6-10
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• 2003

Accurate description of starting transient history allows and justifies the use of small margin of safety for the engine parts, resulting in high motor mass ratio in addition to satisfying the control and guidance requirements of the vehicle. Studies have been carried out for the prediction and reduction of ignition peak and pressure-rise rate during the starting transient of solid rocket motors. Numerical studies have been carried out using a two dimensional Navier-Stokes solver. It has been inferred through the parametric studies that, in the case of solid rocket motors with uniform port, high ignition peak is observed at high spread rate and low pressure-rise rate. In the case of the port with sudden expansion configuration, high ignition peak is observed at relatively high average spread rate and high-pressure rise rate. These studies are expected to aid the designer in reducing the ignition peak by altering the propellant properties or igniter characteristics without sacrificing the motor performance.