• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.236-242
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• 2005

Dynamic Positioning(DP) system maintains ship's position (fixed location or predetermined track) exclusively by means of CPPs and thrusters. To generate the control input adequate to various situation an integrated controller for CPPs and thrusters is required. The integrated controller is composed of a thrust calculation algorithm and a thrust allocation algorithm. The thrust calculation algorithm generates thrusts in the surge direction and the sway direction from the desired forward and lateral speed and generates a moment about the yaw axis from desired heading angle. The thrust allocation algorithm allocates the generated thrusts and moment to each CPP and thruster. Computer simulations are executed to confirm the effectiveness of the suggested controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2135-2144
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• 2007

This paper presents system design of the slotless double-side Permanent Magnet Linear Synchronous Machine system (PMLSM) through magnetic field analysis and dynamic modeling. In our analysis, 2-D analytical treatments based on the magnetic vector potential were adopted to predict magnetic field with space harmonics by PM mover magnetization and stator winding current. From these, the design parameters such as inductance, Back-emf, and thrust are estimated. And, the electrical dynamic modeling including synchronous speed is completed by calculation of a DC link voltage in effort to obtain the accurate mechanical power from Space Vector Pulse Width Modulation(SVPWM). Therefore, the system design of PMLSM is performed from estimation of design parameters according to PM size and coil turns in magnetic field and from calculation of a DC link voltage to satisfy base speed and base thrust represented as the maximum output power in dynamic modeling. The estimated values from the analysis are verified by the finite element method and experimental results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.85-90
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• 2003

To control spacecraft including satellite, we should understand precisely the performance of propulsion system and the program logic with appropriate format for satellite operations. In this study, the thruster performance functions was generated by using the best curve fitting for performance data from bi-propellant thrusters. Detailed thruster performance data are, in general, company proprietary information, therefore real firing tests were performed to understand the basic characteristics of the performance curve. Experimental rocket motor utilize liquid oxygen and kerosine as propellant and designed average thrust was 100 pound.

• Journal of KSNVE
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• v.10 no.5
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• pp.792-799
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• 2000

Aircraft noise in the vicinity of Kimpo international airport has damaged to large number of people who live in communities. This paper investigates noise exposed area due to aircraft flight based on prediction modeling program INM and flight path data. Especially effect on route for aircraft has been considered. Ti also examines noise impact for various flight modes, such as a thrust cutback climb method.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.126-131
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• 2007

In this paper, Monte Carlo Simulation (MCS) method was used as an uncertainty assessment tool for air flow, net thrust measurement. Uuncertainty sources of the net thrust measurement were analyzed, and the probability distribution characteristics of each source were discussed. Detailed MCS methodology was described including the effect of the number of simulation. Compared to the conventional sensitivity coefficient method, the MCS method has advantage in the uncertainty assessment. The MCS is comparatively simple, convenient and accurate, especially for complex or nonlinear measurement modeling equations. The uncertainty assessment result by MCS was compared with that of the conventional sensitivity coefficient method, and each method gave different result. The uncertainties in the net thrust measurement by the MCS and the conventional sensitivity coefficient method were 0.906% and 1.209%, respectively. It was concluded that the first order Taylor expansion in the conventional sensitivity coefficient method and the nonlinearity of model equation caused the difference. It was noted that the uncertainty assessment method should be selected carefully according to the mathematical characteristics of the model equation of the measurement.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.47-58
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• 2020

In this study, a thrust modulation through oxidizer mass flow rate control and internal ballistic analysis based on Whitmore and Chandlers' models was conducted on a blow-down hybrid rocket using nitrous oxide. The tank pressure prediction considering mass flow rate control of the self-pressuring oxidizer was conducted, and the results showed good agreements with experimental results. In order to verify the internal ballistic analysis, a ground combustion test using a 500 N class hybrid rocket was conducted, and it was confirmed that the experimental results and the analytical results were quite consistent in the chamber pressure and thrust, thereby, a modeling technique capable of predicting the thrust modulation performance is proposed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.3
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• pp.59-66
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• 1998

In this paper, the thrust control of PWM Inverter-Fed SLIM(Single-sided Linear Induction Motor) is achieved with Space Vector control and PI control. The trembling of air gap length which is occurred between the primary winding core and the secondary structure of the SLIM must be minimized in order to get quick response characteristics. First, the equivalent circuits and voltage equations of SLIM are shown on th suitable d-q axis which analyze characteristics of the thrust and the normal force. Also, modeling and analysis of the equivalent circuits transferred d-q axis are able to make robust transient torque from the current regulation in the equivalent circuit. These results exemplified the direct drive of SLIM with the reference speed and torque were verified by experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.695-700
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• 2014

In this paper, we utilize the CMG's momentum bias to control the roll/pitch attitude of the Quad-rotor. While the previous control approaches have used the thrust control approach, we design and add a new momentum controller (using CMG) in order to improve the transient response over the existing methods. The focal point of this paper is the design of a controller for a Quad-rotor's attitude using CMG. This leads to other tasks such as an identification of the model's parameters and mathematical nonlinear modeling. Then, the previous thrust controller is designed based on the linearized model. Finally, the overall system with our designed controller is implemented and tested in real time to show that the Quad-rotor is kept in a good balanced position faster than the traditional thrust-only control approach.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1661-1666
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• 2009

This paper is analyzed the effect on characteristics of thrust force of linear induction motor(LIM) by arc type tester. Many kinds of tester have a rotational shape because of a finite length of railroad. Whereas effects by using rotational type tester are generally unknown. For reason of that, this paper is analyzed the effect on characteristics by rotational type tester using 2D finite element method(FEM), and then is compared a thrust force between linear type tester and rotational type tester. Analysis model is decided by numerical modeling for fitting the LIM for propulsion system of light rail, and it is changed to proper arc model. And then we analyzed the arc and the linear model. Consequently, arc type tester is not only useful experiment but also efficient simulation method, and small error is occurred between linear and arc model.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.13 no.3
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• pp.9-21
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• 2005

The stable motion has been judged by mathematical modeling of the conditions that a rocket flies flexibly to take an active part in atmosphere. In this paper, the rocket conditions consist of the air speed, thrust and automatic attitude control. Aerodynamic force, a critical trust and a critical air speed are determined by comparing mathematical knowledges with eigenfrequencies of vibration equation. And then rocket object model is designed. Parameters and eigenfrequencies are used in dimensionless forms for in general applications by eliminating restrictions such as dimension, weight and select of materials.