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Cheongyang, South Korea

Jeon J.,Chungnam National University | Kim T.,Chungnam National University | Ko Y.,Chungnam National University | Kim S.,Chungnam Provincial Cheongyang College
Proceedings of the International Astronautical Congress, IAC | Year: 2012

In this study, a coaxial shear(gas methane)/swirl(liquid oxygen ; lox) type injectors using gas methane and Lox as propellants were designed and combustion tests were performed to evaluate combustion characteristics according to recess length. In order to evaluate reproducibility, every test were tested two times on each injectors. Combustion characteristic and stability would be represented by Characteristic Exhaust Ve!ocity(C*) and fluctuation of chamber pressure. The experimental results showed that combustion efficiencies were not too different between two injectors and combustion stability was confirmed by pressure fluctuations of two injectors showed lower than 5% during combustion tests. Copyright © (2012) by the International Astronautical Federation. Source


Ko K.-J.,Chungnam National University | Jang S.-M.,Chungnam National University | Park J.-H.,Chungnam National University | Cho H.-W.,Chungnam National University | You D.-J.,Chungnam Provincial Cheongyang College
IEEE Transactions on Magnetics | Year: 2011

In this paper, we investigate the electromagnetic performance of wind power generators with outer permanent magnet rotors on the bases of variations in the turbine characteristics over nominal wind speeds by employing various proposed analytical techniques. We have employed an electromagnetic analytical method for calculating electrical parameters such as back EMF constant, synchronous inductance, and phase resistance on the basis of the magnetic field distribution calculated in previous studies. Moreover, curve fitting and finite element methods have been used for core losses analysis, while the d-q model employing the coordinate transformation theorem has been used for analyzing generation performances. To validate our techniques, we compared the performance results obtained using our analytical methods with those obtained by experimental setups. In addition, we propose optimized wind turbine characteristics for our model from the analysis results of electromagnetic performances obtained by considering three types of turbine characteristics. © 2011 IEEE. Source


Jang S.-M.,Chungnam National University | Choi J.-H.,Chungnam National University | Ko K.-J.,Chungnam National University | You D.-J.,Chungnam Provincial Cheongyang College | Lee J.-P.,Korea Electric Power Research Institute
2010 International Conference on Electrical Machines and Systems, ICEMS2010 | Year: 2010

In high speed applications, the slotless permanent magnet motors appear an attractive solution, being almost intensitive to magneto-motive force harmonics and to pulse width modulation(PWM) current ripple and exhibiting lower stator iron losses and rotor losses (significant with square wave current control). In this paper, performance characteristic analysis of slotless synchronous motor/generator with Halbach array magnet will be dealt. Source


Jeon J.S.,Chungnam National University | Min J.H.,Chungnam National University | Jang J.H.,Chungnam National University | Ko Y.S.,Chungnam National University | Kim S.J.,Chungnam Provincial Cheongyang College
Transactions of the Korean Society of Mechanical Engineers, B | Year: 2013

An injector that uses methane gas (CH4) and liquid oxygen (LOx) as propellants was designed to verify the combustion characteristics of an engine that uses methane, which is one of the next-generation propellants. A swirl/shear coaxial-type injector was used, and flow analysis was performed using Fluent to determine the main design parameters of the injector. A hydraulic test was performed to understand the atomization and spray pattern characteristics of the injector. Next, a combustion test was performed at the design point to understand the ignition and combustion stability. Additional combustion tests were performed according to the O/F ratio to investigate the combustion characteristics and stabilities using the characteristic exhaust velocity (C*) and fluctuation of the chamber pressure. The experimental results showed that the combustion efficiency was greater than 90%, and the pressure fluctuation was lower than 2% under all conditions. © 2013 The Korean Society of Mechanical Engineers. Source


Kim K.-H.,Chungnam Provincial Cheongyang College | Park H.-I.,Chungnam Provincial Cheongyang College | Jang S.-M.,Chungnam Provincial Cheongyang College | You D.-J.,Chungnam Provincial Cheongyang College | Choi J.-Y.,Chungnam Provincial Cheongyang College
IEEE Transactions on Magnetics | Year: 2016

The rare-earth permanent magnet (PM) is commonly used to improve the performance of high-speed electrical machines to compensate for their high production costs, while it is very likely that the demand for high-speed machines will increase in the near future as markets for new technologies continue to grow. However, a high-speed machine is required to have high performance and low manufacturing cost, because mass production is needed for these applications. Therefore, in this paper, a high-speed machine using a ferrite PM was designed to significantly decrease the manufacturing costs. To examine the performance of the high-speed machine suggested in this paper, the performance of a high-speed model using a ferrite PM is compared with that of a SmCo PM model. A high-speed machine with a specification of 3 kW and 30 000 r/min is designed and manufactured. The designed model is analyzed using the finite-element method. Finally, the no-load back electromotive force in each model is examined through a back-to-back experiment. © 2016 IEEE. Source

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