• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.427-431
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• 1996

The MRAS proposed by Schauder [8] is modified to improve robustness to the change of load torque and/or the variation of the stator resistance. The difference between the voltage and the current model is fed into the current model via proportional and integral gains. In order to generalize the MRAS, supposing that the rotor speed is time varying, we add a compensating term to the current model. It does not alter the Popov's integral inequality condition. Also, the asymptotic stability of the modified MRAS (MMRAS) is shown with the stability proof technique as in the original paper. By the simulation works, it is verified that the MMRAS obtains improved performance than the original MRAS.

• Journal of Magnetics
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• v.19 no.4
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• pp.411-417
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• 2014

This paper presents the shape optimization of a permanent magnet synchronous motor to reduce the torque ripple and iron loss. Specifically, the harmonics of the electromotive force and cogging torque are decreased by adjusting the permanent magnet arrangement and non-uniform air gap length. In addition, an additional flux path along the q-axis is proposed with a unique rotor shape to increase the q-axis inductance and reluctance torque. The improvement in the performance of the proposed model is verified with simulated and experimental results.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.146-149
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• 1999

A 30kVA superconducting generator has been designed, developed and successfully tested recently. The design is based on 2-dimensional electromagnetic field analysis. The rotor has been wound with superconducting wire of Nb-Ti alloy. The stator has the air-gap type armature windings. Open-circuit test, short-circuit test and lamp load test have been conducted. The details of design program, design, machinebuilding, test results and conclusions are given in this paper.

• Fibers and Polymers
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• v.5 no.3
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• pp.204-208
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• 2004

The present paper reports the detailed study on the splicing behavior of viscose staple fiber yarns made from ring, rotor, friction and air-jet spinning technologies. The linear density of all the yearns was kept constant at 29.5 tex. The splicing parameters like splicing pressure and duration of the splicing were taken as variables. Three levels of splicing pressure at constant splicing duration and three levels of splicing durations at constant splicing pressure were considered. Splices were introduced at all these levels for the four different technologies. These splices were tested for their tensile properties and the properties of splices were evaluated in terms of retained splice strength (RSS) and splice break ratio (SBR). The splice photographs were taken and splices were analyzed for their structure and for diameter profile along the length of the splice.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.75-78
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• 1989

In this paper, A last time delay damper is presented for HB ( HyBrid ) step motor, which has large oscillation characteristics.The design objective is to develop a cost-effective and good-performance damper that would be applyed to HB step motor / driver system without the addition of transducer that would add a weight, size and cost to the system. The Back EMF signal which is recovered from current and voltage signal is used for the measuring the rotor position. It would be possible to get more accurate delay time for the motor driver system. It is proved that the maximum overshoot can be reduced to 13% at stopping through experiment.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.264-267
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• 1989

In the vector controlled induction machine drives, mechanical speed sensors such as shaft encoder and resolver have been used. However, the mechanical speed sensors present some problems and restrict the wide applications of high performance AC drives. This paper describes the vector control strategy with the speed estimation algorithm in which motor slip frequency is calculated. Also, the angle deviation of the rotor flux vector is calculated and instaneously compensated to keep the q axis flux zero in the rotationary reference frame.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2281-2283
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• 2004

In this paper, we show the vector control performances for the parallel-connected motor drive system using the indirect vector control and the proposed vector control. The suggested estimation scheme of the rotor flux position is presented to reduce the sensitivity due to the load difference between the motors. To confirm the validity of the proposed control method, we compare the simulation results of the proposed control method with those of the conventional indirect vector control method. The simulation results show that the proposed control method is more effective for a change in the load torque.

• 열병합발전
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• s.36
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• pp.16-21
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• 2003

For many years, T/G Supplier has constructed a number of thermal power plants and researched to improve the performance and the reliability of steam turbine, which are achieved by advances in design and materials technology. In recent, interest is renewed in advance steam condition as means of improving economy of thermal power plant and reducing environmental pollution. Improvements in the maximum power have been driven by the development of advanced rotor and bucket material and longer last stage bucket. Improvements in efficiency have been brought through advance in mechanical efficiency and thermodynamic efficiency. This paper describes a number of new steam path design features introduced to the steam turbine product. And also this paper describes new design technologies' development, new technologies' trend and technologies' development for ultra-super critical steam turbine.

• The KSFM Journal of Fluid Machinery
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• v.5 no.1 s.14
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• pp.42-48
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• 2002

In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stalls, were observed alternately and irregularly at some flow rates where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the wavelet transform analysis. It was about 45 percents of rotor circumferential space at 300 rpm and not dependent on flow rate.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.99-105
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• 2001

In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stall, were observed alternately and irregularly at some flow rate where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the Wavelet transform analysis. It was about 45 percents of rotor circumferential space at 3000 rpm and not dependent on flow rate.