• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.101-107
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• 2020

In this paper, step-curing, which includes the change of curing temperature on the curing process, was applied to reduce curing day of HTPB/AP based propellant. This study targets the improvement of productivity of HTPB/AP based solid rocket motor. Comparison of mechanical properties of propellant resulted in the change of normal curing condition (60℃, 5 days) to step-curing condition (60℃, 1 day / 65℃, 3 days). Post-cure test was conducted to determine the impact on the shelf life of the solid rocket motor. The aging characteristics of propellants were analyzed by measuring mechanical properties and thermal expansion factor. To step-cured propellant, accelerated aging test was performed for 12 weeks, followed by tensile test. Sm(bar) and Em(%) were higher than 8 bar and 40% each, showing excellent mechanical properties.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.650-652
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• 2001

The permanent magnet in hybrid step motor is magnetized to the axial direction. Accordingly the 2D analysis method such as 2D finite element method cannot guarantee the analysis accuracy. In this paper, the characteristics of hybrid type step motor are analyzed by using 3D equivalent magnetic circuit network method(3D EMCNM). 3D EMCNM supplements magnetic equivalent circuit by numerical technique using distributive magnetic circuit parameter and 3D EMCNM is used for the accurate and efficient analysis. The validity of the analysis results is confirmed by comparing with the experimental ones.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.220-226
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• 2000

High precision step motor using Terfenol-D linear actuators is proposed and its performance is tested. Four Terfenol-D linear actuators are set up perpendicular to the rotor and saw-tooth current signals are applied on the actuators. It was found that the rotation angle is increased as the excitation current, the inertia of the rotor, and the contact force between the rotor and the push device are increased. The rotation angle per step of $0.001^{\circ}$ and blocking torque of 0.2Nm are achieved. The effect of the time delay between the excitation signals is also investigated.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.777-779
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• 2001

In this study, we have estimated the brushless DC motor parameters by means of back-emf measurement and step input test. The validity of proposed parameter estimation method is confirmed by step res pons experiment. And the reasonable digital controller is designed with the root locus method of motor transfer function and revised Ziegler-Nichols gain determination method. The system stability is experimentally verified by the frequency domain analysis used Bode plot.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.12
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• pp.797-806
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• 2000

In this paper, the torque characteristics and the bar loss distribution are analyzed when a general cage induction motor with skewed slots is fed by a 6-step inverter. For the electromagnetic analysis, time-stepping finite element method is used. And the multi-slice technique and sliding surface technique are respectively utilized to consider the skew effect and the rotation of the rotor. As a result, the effects of skewed rotor bar and the inverter output voltage on the characteristics of the torque and bar loss in the rotor are investigated. The simulation results are verified by measurement of flux density distribution axially in the stator teeth.

• Asia pacific journal of information systems
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• v.8 no.1
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• pp.27-42
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• 1998

In a competitive environment, selecting and effectively pursing the right information system investments can be a key factor in sustaining corporate viability and prosperity. This study applies quality function deployment(QFD) to the determination of information system development priority. The intent of QFD is to incorporate the needs of a customer through the various stages of product planning and manufacturing into a final product. The basic idea of our study is to translate the core competence and the competitive environment into the business strategy, and the critical success factors, and subsequently into information system development priority. Our method is applied to a motor company for the determination of the information system development priority. The company case is illustrated step by step with real data of the company and motor market.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.723-725
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• 2000

This paper presents a parameter identification method to estimate the stator resistance. stator inductance, rotor resistance and rotor inductance of the induction motor. A step voltage is applied across the stator terminals while the machine is in the standstill condition, and the resulting stator voltage and current response are measured. Observer/Kalman Filter Identification(OKID) algorithm is used to estimate induction motor parameters. Simulation results are presented to verify the identified model.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.870-872
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• 2000

This paper deals with the effect of rotor thickness variation and winding method in high torque hybrid Permanent Magnet(PM) step motor. As these parameters vary. The flux distribution in airgap and torque characteristics are influenced, which is related to output power. efficiency and cost. These parameters and characteristic variations were evaluated by using Finite Element Method (FEM) and experiment method. From these results. Characteristic analysis for the optimum design was studied and prototype motor was made to test performance analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.749-751
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• 2004

This paper analyzed the characteristics of the claw pole PM step motor by using 3D FEM. In case of analysing this type of motor, 3 dimensional analysis is necessary for an accurate analysis due to the magnetizing component of the z-axis direction. As a main design variable, the magnetization, width and the effects of skewing was selected. The variation of the detent torque and the back EMF depending on the shape of the pole is also shown.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.69-77
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• 2012

We propose a PLL-type position control method for step motors. Our control method considerably improves the instability problem at rapid acceleration or deceleration, which is a major problem of conventional open loop control methods. Moreover, our controller reduces the steady state position error to zero and guarantees lower vibration and acoustic noise at high speed. Also, our controller can produce more torque at high speed, and hence it can extend the controllable velocity range. To demonstrate the practical significance of our control method, we present some simulation results for a commercially available step motor using Simulink.