• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.76-81
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• 2009

A nonlinear pressure controller to actively regulate the thrust of a solid propulsion system is presented. To compensate for the parametric uncertainties with respect to the chamber pressure induced by changing nozzle throat area, Lyapunov-based parameter adaptation method has been applied. In order to verify the effectiveness of the proposed control method, the experiments were carried out using the cold gas test equipment that can simulate the operating environment of variable thrust solid propulsion system. The experiment results show that the nonlinear pressure controller has better performance than conventional P and PI controller.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.73-80
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• 2015

It had been almost a half century since Apollo Mission was ended. However, in these days, a lot of researches are being conducted for restoration and making improvements in technologies used in Saturn V rocket's development. This study reviews the first stage of Saturn V rocket(S-IC), from development history to technologies in various subsystems such as engine purge system, POGO suppression system, hydraulic and pneumatic control system, propellant dispersion system, telemetry system and retrorocket system. Understandings of S-IC stage's operation systems would be helpful in understanding of launch vehicle system and reduction of time and cost in future development process.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.4
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• pp.47-58
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• 2002

The pressure regulator has been developed as a pressure-control device of propellant tank in KSR-III. The pressurization system of KSR-III is a basic pressurization system composed of pressurant, He tank and propellant tank. The pressure-control regulator is the most important part of gas-pressurized feed system along with He tank, pyrovalve and He fill valve. The first model of the regulator is tested to satisfy in leakage, strength and basic performance. The second model is tested in the overall test of the KSR-III propulsion system using water. From the test result of the second model, we conclude that the capacity of valve(Cv) must be increased in real system. The third model is modified and tested in the overall test of KSR-III propulsion system using propellant. Finally, the pressure-control regulator is qualified from firing test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1612-1618
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• 2021

The telegraph controller is a device used to control the speed of a ship, and it is a device that has a very direct effect on the safety of the crew. Accordingly, ship owners demand very high reliability of the telegraph controller, and the classification trend is to introduce HILS (hardware in loop system) test as a method to verify reliability. Therefore, in this paper, an electric propulsion ship was modeled to perform the HILS test of the Telegraph controller. For modeling, the specifications of the electric propulsion tug boat were defined, and the battery parts, propulsion motor parts, and ship model parts were modeled. In addition, various operation scenarios were defined and the Telegraph controller was modeled accordingly. Finally, the results of the integrated model were confirmed through simulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.2
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• pp.181-187
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• 2018

In order for the probe to perform ocean exploration and survey research, it is necessary to adjust the position of the ship as desired by dynamic positioning system. The dynamic positioning system of T/S NARA is applied to K-POS dynamic positioning system of Kongsberg, which makes maintaining the ship's position, changing position and heading control possible. T/S NARA is not capable of dynamic positioning if one or more propulsive forces are lost with DP Level One. However, it is predicted that dynamic positioning can be achieved even at the time of missing one thrust in a good sea condition. Therefore, we want to analyze the effect of each propulsion on the performance of dynamic position system. When one of the bow thruster and azimuth thrusters lost their propulsion, maintaining the ship's position, changing position and heading control performance were compared and analyzed. If the situation occurred disable from using the bow thruster, they can not maintain ship's position. Azimuth thruster was influential for the ship's position control and bow thruster was influential in heading control. The excellent dynamic positioning performance can be achieved, considering the propulsion power that will have a impact on each situation in the future.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.129-135
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• 2014

In the paper, we propose a design method for the logistics transportation system using magnetic levitation that has a good characteristics without mechanical friction, noise and dust. The proposed transportation system consists of a levitation control system and a propulsion control system. Magnetic levitation system is an electromagnetic suspension system in which electromagnet generates magnetic attractive force and the attractive force pulls the rail. We design a PID controller for the current control of electromagnets. We use linear induction motors for propulsion of the proposed logistics transportation system and adapt the space vector PWM method for the propulsion control system. The proposed transportation system using magnetic levitation is verified performances through levitation and propulsion experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.147-150
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• 2005

Space launch vehicles mainly use the liquid-propellant propulsion system which has easy thrust control ability and high specific impulse for that the payload like satellite and spacecraft should be entered into exact orbit. However, the liquid-propellant propulsion system is very difficult to develop because it is more complicate than the solid rocket propulsion system and demands very high technology. In space launch vehicle developing procedure the system design level is very important thing to reduce cost, shorten schedule, and improve the performance. The system design process was introduced for selecting the best liquid-propellant propulsion system on this paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.923-929
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• 2019

The stability of the propulsion system is crucial for the autonomous vessel. Multiple power generation and propulsion systems should be provided for the stability of the propulsion system. High power generation capacity is calculated for stability, resulting in economical decline due to low load operation. To solve this problem, we need to optimize the power system. In this paper, an OPMS for electric propulsion ship is constructed. The OPMS consists of a hybrid power generation system, an energy storage system, and a control load system. The power generation system consists of a dual fuel engine, the energy storage system is a battery, and the control load system consists of the propulsion load, continuous load, intermittent load, cargo part load and deck machine load. The power system was constructed by modeling the characteristics of each system. For the experiment, a scenario based on ship operation was prepared and the stability and economical efficiency were compared with existing electric propulsion ships.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.26-34
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• 2022

The propulsion system of geostationary orbiting satellites is typically used to raise the orbit into a transfer orbit, maintain the orbital position in the south/north, east/west direction in regular operation, and accumulate momentum in the south/north and east/west direction. Recently, when an electric propulsion system is used in a geostationary orbit satellite, the payload capacity can be increased by about 40% compared to a chemical propulsion system. However, despite these advantages, using an electric propulsion system has several limitations that should apply to all geostationary orbiting satellites. This paper discusses the operational constraints to consider when developing an indigenous geostationary satellite using a fully electric propulsion, radiation exposure, and control mechanism design due to unit displacement and floating ground-design. A high-voltage control unit for electric drives were analyzed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.1
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• pp.71-79
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• 2024

In compliance with environmental regulations at sea and the introduction of unmanned autonomous ships, electric propulsion ships are garnering significant attention. Induction machines used as propulsion electric motor (PEM) have maintenance advantages, but speed control is very complicated and difficult. One of the most commonly used techniques for speed control is DTC (direct torque control). DTC is simple in the reference frame transformation and the stator flux calculation. Meanwhile, two-level and three-level voltage source inverters (VSI) are predominantly used. The three-level VSI has more flexibility in voltage space vector selection compared to the two-level VSI. In this paper, speed is controlled using the DTC method based on the specifications of the PEM. The speed controller employs a PI controller with anti-windup functionality. In addition, the characteristics of the two-level VSI and three-level VSI are compared under identical conditions. It was confirmed through simulation that proper control of speed and torque has been achieved. In particular, the torque ripple was small and control was possible with a low DC voltage at low speed in the three-level VSI. The study confirmed that the application of DTC, using a three-level VSI, contributes to enhancing the system's response performance.