• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.623_624
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• 2009

This paper deals with the characteristic analysis of electro-magnet (EM)-permanent magnet (PM) hybrid levitation and propulsion device for magnetically levitated (maglev) vehicles. Several machine characteristics such as levitation force with/without control current and thrust are described. In order to verify the analysis results and feasibility of high-speed operation of the maglev vehicle, real-scale static test set is implemented and tested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.240-243
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• 2008

An experimental study was conducted to understand spray characteristics of rotating fuel nozzle by using high speed rotational system. The experimental apparatus consist of a fuel injection system, high speed rotational system, and acrylic case. The test is performed with several diameters and number of injection orifices. Spray characteristics such as droplet size and velocity are measured by PDPA(Phase Doppler Particle Analyzer). From the test results, we could understand the spray characteristics of rotating fuel nozzle with orifice number and diameter.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.83-88
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• 2007

The spray characteristics and liquid column penetration of steady and pulsed injection measurements have been experimentally studied using high speed camera in liquid jets injected into subsonic crossflow. The objectives of this research are to comparison the spray characteristics of steady injection with pulsed injection. Moreover. the effects of frequency are also studied. As the result, This research has been showed that pulsed injection has different penetration compared with steady injection.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.813-818
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• 2005

In this paper, a re-adhesion control scheme is proposed for 1C2M propulsion system of TTX. The possibility of slip between wheel and rail in railway system is increasing because of the tendency of high speed and a climatic change. This slip results in the decrease of adhesive effort between this wheel and rail, so the control strategy of traction effort which can reduce the speed promptly and make most use of the maximum adhesive force is absolutely necessary. This paper describes the modeling of the TTX system, and this system is verified by the simulation.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.175-175
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• 2012

Proper shaft alignment is one of the most important actions during the design of the propulsion system. The stiffness of recently designed marine propulsion shafting has been increasing remarkably, whereas hull structures have become more likely to deform as a result of optimized design of the scantlings and the high tensile steel. Therefore, to obtain the optimum status in shafting alignment at the design stage, it is strongly recommended that the change of bearing reaction force depending on ballast/load condition, the bending moment force occurred by propeller thrust, elastic deformation of bearing occurred by vertical load of shaft mass and etc., should be considered. This paper dealing with introduction of shaft alignment concerning long shaft for high speed vessel and review its reliability evaluation theoretically.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.150-155
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• 2012

Water jet propulsion system has low efficiency than screw propeller at low speed, but has been applied in high speed ship due to its better cavitation performance and high rotation capacity. In this study, a numerical analysis was conduct to understand the flow in the propulsion system of 200HP grade water jet for small ship. As the result, it could be confirmed that total pressure and force of the flow was increased through the impeller and the straight-ability of discharging flow to outlet was improved by guide vane. Also, the reliability of numerical analysis was secured by comparing peripheral velocity calculated by design values with that calculated by numerical analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.240-244
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• 2004

Characteristics of steady and unsteady cavitation in a turbopump inducer were investigated in this paper. To see the effect of tip clearance on the inducer performance, three cases of tip clearance were tested. The helical inducer, which has two blades with inlet tip blade angle of 7.8 degree and tip solidity of 2.7, was tested in the water. In the non-cavitating condition, the inducer head decreased with increase in the tip clearance. Rotating cavitation and cavitation surge were observed through unsteady pressure measurements at the inducer inlet. The cell number and propagation speed of the rotating cavitation were determined through cross-correlation analysis. During the rotating cavitation one cell rotated at the same rotational speed as that of the inducer rotation and the cavitation surge did not rotate. The critical cavitation number increased with increase in the tip clearance at the same flow rate, but the change of critical cavitation number was small at the nominal flow rate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.335-340
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• 2004

On a liquid propellant PPT, the discharge processes that discharge was initiated and plasma was accelerated was observed by using a ultra high speed camera. Liquid propellant PPT is a pulsed plasma thruster using liquid as propellant. Our past study showed the successful operation of liquid propellant PPT and the thruster showed high specific impulse. However, its acceleration mechanism has not been clarified. In this study we observed the plasma acceleration processes in order to deepen our understanding of the acceleration mechanism.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.347-352
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• 2004

The unsteady aerodynamic characteristics of an aerofoil gradually accelerating or decelerating at subsonic speeds are investigated through two-dimensional, unsteady, compressible Navier-Stokes simulations. An acceleration factor is defined to provide various acceleration or deceleration characters of the time-dependent flow over the aerofoil. The results show that an increase in the absolute value of the non-dimensional acceleration factor leads to a lesser change in the location and range of flow featues such as shockwave and boundary layer separation in a specific time range. Generally, the gradual speed-up and speed-down of the subsonic aerofoil results in different aerodynamic characteristics whose changes are more significant at angles of attack.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.401-407
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• 2004

This study proposes a interim development result for the l-㎾ class small wind turbine system, which is applicable to relatively low wind speed regions like Korea and has the variable pitch control mechanism. In the aerodynamic design of the wind turbine blade, parametric studies were carried out to determine an optimum aerodynamic configuration which is not only more efficient at low wind speed but whose diameter is not much larger than similar class other blades. A light composite structure, which can endure effectively various loads, was newly designed. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Moreover both structural safety and stability were verified through the full-scale structural test.