• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.1015-1021
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• 2014

This paper proposes the center distributed embroidery machine structure with 1,500 RPM, 52 heads for productivity and large sized embroidery goods. The synchronous velocity controller is adopted for control of the 2-axis distributed embroidery machine and the DOB(Disturbance Observer) is also adopted for minimizing disturbances caused by needle cams. For driving experiments of 2-axis center distributed driving structure, two conventional 26 heads 1,500RPM embroidery machines are used. It was shown that the center distributed driving structure with 2-axis synchronous control can be one way for implementing a large embroidery machine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.391-394
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• 2002

This paper introduces that the lathe optimize for main and sub spindle's synchronous in Opening-CNC. In view of optimal design, the mathematical modelling and the frequency domain analysis of spindle's system are performed. For the compensation of synchronous error in compounded manufacture process, the optimization method of motor drive's control parameter and the related parameter is proposed. By the experiment in prototype machines using the server/client program, the validity of the proposed method is verified.

• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.21-26
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• 2001

Superconducting synchronous generators and motors are designed based on 2 dimensional electro-magnetic approach. In the case of generator, if the machine output rating and terminal voltage are decided the armature rating current will be decided automatically according to its power factor. However, in the case of motor, if the output rating is given with [hp] or [kw] units, the armature terminal voltage and current are not decided directly because the machines armature input power and mechanical output are different by way of losses. So in order to calculate the armature current more accurately. the machine losses must be included in the design procedure. In this paper the machine loss of superconducting motor are analyzed and used for decision of the armature input power and current. Moreover, the differences of voltage equations between superconducting synchronous generator and motor are considered.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.812-819
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• 2015

This paper presents a new approach for simulating the internal faults of synchronous machines using distributed computing and Large Change Sensitivity (LCS) analysis. LCS analysis caters for a parallel solution of 3-phase model of a faulted machine within the symmetrical component-based model of interconnected network. The proposed method considers dynamic behavior of the faulty machine and connected system and tries to accurately solve the synchronous machine’s internal fault conditions in the system. The proposed method is implemented in stand-alone FORTRAN-based phasor software and the results have been compared with available recordings from real networks and precisely simulated faults by use of the ATP/EMTP as a time domain software package. An encouraging correlation between the simulation results using proposed method, ATP simulation and measurements was observed and reported. The simplified approach also enables engineers to quickly investigate their particular cases with a reasonable precision.

• Journal of Magnetics
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• v.18 no.3
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• pp.260-267
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• 2013

In this paper a general 2-D model of a large air-gap synchronous machine either with non-magnetic or magnetic core rotor is investigated and electrical characteristics of the machine are analytically calculated. Considering the general model, analytical equations for magnetic field density in different regions of the large air-gap machine are calculated. In addition, self and mutual inductances in the proposed model of the machine have been developed, which are the most important parameters in the electromagnetic design and transient analysis of synchronous machines. Finite element simulation has also been performed to verify the obtained results from the equations. Analytical results show good agreement with FEM results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.207-214
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• 2005

After more than 100 years of development, rotating electric machines are a mature industrial product. Nevertheless, improvements are still possible for specific applications, and it is likely that the major evolution will be promoted by new materials and unconventional structures. Till now, plastic materials are an infrequent choice for the electric machines structural parts, but pioneering applications, such as aeronautical components, let some technological scouting: a low-weight/high-efficiency plastic axial flux motor for a solar flying platform is presented as an example of combined new-material/new-geometry development. The basic design aspects and the prototyping choices are presented and discussed together with the first experimental results.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.93-95
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• 2008

Nowadays more attention is paid to the developing high efficiency electrical machines for energy saving and protection of natural resources. In general, the electromagnetic losses appearing in electrical machines are widely classified into copper loss, core loss and rotor loss. Particularly, in permanent magnet (PM) machines, core loss forms a larger portion of the total losses than in another machine. So, satisfactory prediction of core loss at the design or analysis stage of PM machines is essential to active high efficiency and high performance. This paper deals with analysis of magnetic field distribution due to geometry of stator core for magnetic core loss calculation of multi-pole PM synchronous machine.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.38-43
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• 2004

1MW class superconducting synchronous motor is designed considering several conditions such as superconducting wire length, machine efficiency and size. As the machine is larger and larger, the superconducting machine shows the advantages more and more over the conventional machines. Although the advantages at 1MW rating are not so great, the design approach to get an appropriate result would be very helpful for larger superconducting synchronous machine design. Major design concerns are focused on reducing expensive Bi-2223 HTS(High Temperature Superconducting) wire which is used for superconducting field coil carrying the rating current around 30K(-243$^{\circ}C$) while the machine efficiency is higher than conventional motors or generators with the same rating. Furthermore, some iron cored structure is considered to reduce the HTS wire requirement without bad effect on machine performances such as sinusoidal armature voltage waveform, synchronous reactance and so on.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.143-151
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• 2004

High-speed permanent magnet machines are likely to be a key technology for electric drives and motion control systems for many applications, since they are conductive to high efficiency, high power density, small size and low weight. In high-speed machines, the permanent magnets are often contained within a retaining sleeve. However, the sleeve and the magnets are exposed to high order flux harmonics, which cause parasitic eddy current losses. Rotor losses of high-speed machines are of great importance especially in high-speed applications, because losses heat the rotor, which is often very compact construction and thereby difficult to cool. This causes a danger of demagnetization of the NdFeB permanent magnets. Therefore, special attention should be paid to the prediction of the rotor losses. This paper is concerned with the rotor losses in permanent magnet high-speed machines that are caused by permeance variation due to stator slotting. First, the flux harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. And then, the rectilinear model was used to calculate rotor losses in permanent magnet machines. Finally, Poynting vector have been used to investigate the rotor eddy current losses of high-speed Permanent magnet machine.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.4
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• pp.39-48
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• 2009

Asynchronous sequential machines, or clockless logic circuits, have several advantages over synchronous machines such as fast operation speed, low power consumption, etc. In this paper, we propose a novel robust controller for input/output asynchronous sequential machines with uncertain state transitions. Due to model uncertainties or inner failures, the state transition function of the considered asynchronous machine is not completely known. In this study, we present a formulation to model this kind of asynchronous machines ana using generalized reachability matrices, we address the condition for the existence of an appropriate controller such that the closed-loop behavior matches that of a prescribed model. Based on the previous research results, we sketch design procedure of the proposed controller and analyze the stable-state operation of the closed-loop system.