• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1013-1018
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• 2003

This paper deals with the secondary excited induction generator applied to random energy input generation system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled inverter connected to the secondary windings supplies the secondary current with slip frequency. For testing the appropriateness of this paper, the input torque simulator, which generate the statistically varied wave power input torque in the laboratory to drive the secondary excited induction generator, are constructed. The experimental and numerical results show the advantage of secondary excited induction generator system for the random input wave generation system.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.29-33
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• 1998

In this paper, a new dynamic overmodulation strategy is proposed for vector-controlled induction motor drive, and a comparison experiment with conventional schemes are also performed. In overmodulation region, the proposed overmodulation scheme allocates the output voltage of inverter so that synchronous d-axis voltage is diminished in proposed overmodulation scheme allocates the output voltage of inverter so that synchronous d-axis voltage is diminished in proportion as reference voltage exceeds hexagon boundary. As a result, d-axis current is decreased in the overmodulation region, which improves the dynamic performance of torque control considering the current dynamics of induction motor. The conspicuous improvement of the proposed scheme over conventional ones is observed in experimental results.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.623-630
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• 2010

This paper presents the implementation and characteristic analysis of a drive system for a three-phase permanent magnet motor with independent excitation winding that is applicable for electric bicycles. The design features improves the phase current waveform, output power, and torque by using advance angle control. This adjusts the phase angle of each phase current in relation to back EMF. In addition, a DC-side PI current control is performed through PWM generation circuit using a low-cost one-chip microcontroller and a CPLD chip, resulting in reduced system costs. Finally, the validity of this control scheme for driving electric bicycles and output/torque improvement characteristics are verified through analysis and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.42-48
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• 2011

Generally, the structure without the stator core Axial Field Permanent Magnet (AFPM) generator was simple and there was nearly no cogging toque. And because it had the wide driving rate area, it had been being mainly used in the small wind power generation system. However, AFPM generator with non-slotted stator can't generate high voltage at low wind speed due to long air-gap. It is the reason of output efficiency drop. Therefore, in this paper, the AFPM synchronous generator with internal rotor and dual slotted stators for the small wind turbine is studied, and deal with a cogging torque minimization through the determination of optimum pole-arc ratio.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.51-56
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• 2007

In this paper, control schemes are developed for a propulsion system(Converter/Inverter) in electrical train. A robust controller for PWM converter is proposed. The converter controller consists of a PI controller for DC output voltage and a current controller using error-space approach for maintaining the sinusoidal current waveform and unity power factor. This proposed method is based on characteristic ratio assignment(CRA) method which has the advantage to design the optimal gain to meet the referenced response and overshoot within the limit range. Inverter system is controlled by vector control and slip frequency control. At low speed region, vector control scheme is applied to control instantaneous torque and slip frequency control is performed under overmodulation region and one pulse mode. Because output voltage of converter contains harmonics ripple at twice input ac line frequency, control scheme is developed to reduce the pulsating torque current. The performance of propulsion system will be verified by simulation and prototype experimental results.

• Proceedings of the KIEE Conference
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• summer
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• pp.914-916
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• 2004

In this paper, finite element analysis for a PMASynRM is presented and the characteristic analysis of inductance and torque is performed under the effect of saturation. The focus of this paper is characteristic analysis of d and q-axis inductances and torque according to magnetizing quantity of interior permanent magnet for PMASynRM. The d and q-axis current component ratios, load angles of a PMASynRM are investigated quantitatively on the basis of the proposed analysis method and the experimental test. Comparisons are given with output characteristic curves of normal SynRM and those according to the load in PMASynRM, respectively. And it is confirmed that the proposed model results in high output power performance.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.785-788
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• 2003

Many application in robotics, telecommunication, automation systems etc require powerful actuator. The powerful actuator have Speeds up to high speed and high output torque efficiencies. To accomplish a powerful actuator, these powerful motor have to be combined with gearheads of the same outer diameter. So, we have developed BLDC motor and planetary type gearheads as powerful actuator. The BLDC motor have advantages that compact structure, high efficiency, high reliability. The Planetary type gearheads have advantages that same-axle structure, high torque transmission, low noise in comparison with spur gearheads. In this study included BLDC motor and planetary type gearheads design, manufacture. This time study performed for actuator of precision mechanism.

• Journal of Periodontal and Implant Science
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• v.43 no.5
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• pp.221-226
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• 2013

Purpose: This study aimed to assess the combined effect of dismantling before sterilization and aging on the accuracy (${\pm}10%$ of the target torque) of spring-style mechanical torque devices (S-S MTDs). Methods: Twenty new S-SMTDs from two different manufacturers (Nobel Biocare and Straumann: 10 of each type) were selected and divided into two groups, namely, case (group A) and control (group B). For sterilization, 100 cycles of autoclaving were performed in 100 sequences. In each sequence, 10 repetitions of peak torque values were registered for aging. To measure and assess the output of each device, a Tohnichi torque gauge was used (P<0.05). Results: Before steam sterilization, all of the tested devices stayed within 10% of their target values. After 100 cycles of steam sterilization and aging with or without dismantling of the devices, the Nobel Biocare devices stayed within 10% of their target torque. In the Straumann devices, despite the significant difference between the peak torque and target torque values, the absolute error values stayed within 10% of their target torque. Conclusion: Within the limitations of this study, there was no significant difference between the mean and absolute value of error between Nobel Biocare and Straumann S-S MTDs.

• Tribology and Lubricants
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• v.33 no.2
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• pp.71-78
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• 2017

The drag torque in the wet clutch system of a dual clutch transmission system is investigated because it is relatively high, up to 10 of the total output torque of the engine, even when the clutch is in the disengagement state with zero torque transfer. Drag torque results from the shear resistance of the DCTF between the friction pad and separator plate. To reduce the drag torque for ensuring fuel economy, the groove pattern of the wet clutch friction pad is designed to have a high flow rate through the pattern groove. In this study, four types of groove patterns on the friction pad are designed. The volume fraction of the DCTF (VOF) and hydrodynamic pressure developments in the gap between the friction pad and separator plate are computed to correlate with the computation of the drag torque. From the computational results, it is found that a high VOF and hydrodynamics increase the drag torque resulting from the shear resistance of the DCTF. Therefore, a patterned groove design should be used for increasing the flow rate to have more air parts in the gap to reduce the drag torque. In this study, ANSYS FLUENT is used to solve the flow analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.4
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• pp.10-18
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• 2007

A tested micro axial-type turbine consists of two stages and its mean radius of rotor flow passage is 8.4 mm. This turbine could be applied to a driver of micro power system, and its rotational speed in the unloaded state reaches to 100,000 RPM. The performance of this system is sensitive depending on the blade angles of the rotor and stator because it is operated in a low partial admission rate, so a performance test is conducted through measuring the specific output power and the net specific output torque with various blade angles on the nozzle, stator and rotor. The experimental results show that the net specific output torque is varied by 15% by changing the rotor blade angle, and the optimal incidence angle is about $10.3^{\circ}$.