• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.737-739
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• 2015

In this paper, a novel method of sensorless control scheme is proposed to apply on a single phase hybrid SRM used in high speed operation. The proposed method utilizes beneficially permanent magnet field whose performance is motor parameter independent to estimate the rotor position. Also, the current slope is adopted to complete the sensorless control when the motor running with heavy torque at high speed condition. Through this approach, the adjustable turn on/off position can be achieved without prior knowledge of inductance profile which is always employed by many sensorless schemes. And this paper may offer an available method to do the sensorless control in hybrid SRM used for high speed running.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.279-284
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• 1999

Although the switched reluctance motor (SRM) has a several advantages such as simple magnetic structure, robustness, wide range of speed characteristics and simple driving, it has a considerable inherent torque ripple and speed variation duet to the driving characteristics of pulse current waveform and the nonlinear inductance profile. The high torque ripple and speed variation inhibits wide application. The minimization of the torque ripple is very important in high performance servo drive applications, which require smooth operation with minimum torque pulsations. This paper presents the new SRM torque modeling technique for the control of instantaneous torque. The SRM is modeled by the database of torque profiles for every small variation in currents and rotor angles, which is inferred from the several measured data by the adaptive neuro-fuzzy inference technique. Simulation results demonstrating the effectiveness of proposed torque modeling technique are presented.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.193-200
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• 1999

An unstructured implicit Euler solver is parallelized on a Cray T3E. Spatial discretization is accomplished by a cell-centered finite volume formulation using an unpwind flux differencing. Time is advanced by the Gauss-Seidel implicit scheme. Domain decomposition is accomplished by using the k-way N-partitioning method developed by Karypis. In order to analyze the parallel performance of the solver, flows over a 2-D NACA 0012 airfoil and a 3-D F-5 wing were investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.753-759
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• 2009

Feed-forward neural networks have been widely used as function approximation tools in the context of global approximate optimization. In the present study, a wavelet neural network (WNN) which is based on wavelet transform theory is suggested as an alternative to a traditional back-propagation neural network (BPN). The basic theory of wavelet neural network is briefly described, and approximation performance is tested using a nonlinear multimodal function and a composite rotor blade analysis problem. Laplacian of Gaussian function, Mexican function, and Morlet function are considered during the construction of WNN architectures. In addition, approximation results from WNN are compared with those from BPN.

• Journal of computational fluids engineering
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• v.10 no.2
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• pp.15-20
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• 2005

Numerical investigations have been performed to examine the effects of the computational grids on the prediction of the flow characteristics inside the turbine cascades. Three kinds of grid system based on H-type grid are applied to the high-turning transonic turbine rotor blades and comparisons with the experimental data and the numerical results of each grid structure have been done. In addition, the grid sensitivity on the estimation of the blade performances has been investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1795-1800
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• 2000

One of the principal sources of vibration and noise in permanent magnetic machines is cogging torque, which is induced by interaction between the rotor poles and the stator teeth. For its analysis, using finite element analysis is very time consuming and the calculation of performance factors is extremely sensitive to the discretization. Especially, Maxwell stress tensor method is sensitive to the location of integral path. In this paper, a cogging permeance fuction is defined and replaced by the straight line. And it is assumed that the flux density acting on the stator's tooth side is the euqal to the flux density of the slot area. Using this definition and assumption, analytical calculation of cogging torque is presented and validated. And several reduction method is introduced.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.258-263
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• 2011

This study is aimed at obtaining basic design data for Savonius wind turbine, available in the domestic wind environments. To the end, the flow field characteristics around the wind turbine attached with 1/4 wind shield were monitored along with numerical analysis. On the top of this, numerical analysis and experiments on the rpm of the turbine rotor were conducted. As a result, this study found that the numerical analysis results squares with the experiment results and the rpm improves by over 70%.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.205-212
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• 2000

Induction motors. having axial cooling channels in stator and rotor are designed for better cooling performance. Traction motors are one of those examples. And, thermal analysis gain more attention with the Increased demand of the motors, for reliable operation and life prolongation. was Induced to effective thermal conductivity through modeling. Through. fundamental comparison experiment, heat source experiment and transient state experiment, the induction motor using inverter was examined to produce heat source with frequency level and traced to thermal variation at starting and stopping. And thermal analysis using thermal network was compared with a transient state experiment.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.857-862
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• 2003

Numerical investigations have been performed to examine the effects of the computational grids on the prediction of the flow characteristics inside the turbine cascades. Three kinds of grid system based on H-type grid are applied to the high-turning transonic turbine rotor blades and comparisons with the experimental data and the numerical results of each grid structure have been done. In addition, the grid sensitivity on the estimation of the blade performances has been investigated.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.124-128
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• 2002

This Paper propose a novel sensorless drive system for the trapezoidal brushless DC motor in Bow speed region. The inverter DC input voltage is controlled by step-down converter for low speed operation. A indirect rotor position sensing technique based on a detailed analysis of the terminal voltage characterisrics is proposed in this paper. A sensorless drive system is implemented using a TMS320F240 for the main process and IPM(Intelligent Power Module) for the inverter.