• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.337-339
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• 2001

High speed brushless permanent magnet (PM) machines are a key technology for electric drives and motion control systems for many application, since they are conductive to high efficiency, high power density small size and low weight. Proposed slotless PM machine is constructed without stator winding slots. Its stator magnetic material is in the form of a ring and winding have a toroidal configuration and its rotor consists of a 4-pole Halbach array or radially magnetized PM rotor.

• 전기의세계
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• v.28 no.1
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• pp.43-52
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• 1979

Recently, interest in multivalued(MV) logic system has been increased, despites the apparent difficulties for practical application. This is because of the many advantages of the MV compared with the 2-valued logic systems, such as; (a) higher speed of arithmetical operation on account of the smaller number of digits required for a given data, (b) better utilization of data transmission channels on account of the higher information contents per line, (c) potentially higher density of information storage. This paper describes a MV switching theory and experimental MV logic elements based on current-mode logic technique. These elements tried were a 3-stable pulse generator, a ternary AND, a ternary OR, a MT circuit and a ternary inverter. Tristable flops which are indispensable for constituting a ternary shift register are synthesized using these gates. A BCD to TCD decoder, and vice versa, are proposed by using a ternary inverter and some binary gates. Thus, the feasibility of a large scale MV digital system has been demonstrate.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.103-107
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• 2004

Recently, greater attention has been paid to the high-speed generator for its many merits, such as ease of installation, high efficiency and high power density. However, due to their high fundamental frequency, careful consideration needs to be given to both electromagnetic and mechanical design issues. This paper deals with the comparison of two types of permanent magnet high-speed machines. Specifically, the effect of the permanent magnet magnetization pattern on the rotor losses is investigated. On the basis of analytical field analysis and the 2-D finite element method, this paper predicts the flux harmonics and rotor losses under the no-load condition. It is shown that the Halbach magnetization is superior to parallel magnetization in terms of producing rotor losses.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1554-1555
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• 2006

We have studied the backward wave oscillator, a power pulsed generator oscillator at 20 GHz has higher frequency then current one. An absolute instability linear analysis was used for the purpose of designing the slow wave structure. A large diameter of the slow wave structure was adopted to prevent the breakdown brought about by the increase of power density.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1718-1723
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• 2015

The diameter of the rotor of 2MW wind turbine is being developed by a number of companies with more than 80m, reliability and economic efficiency of the wind power generator has been improved. The need for large-scale wind turbine with excellent economy has been attracting attention because the new orders and the location of the wind turbine market has reached a limit. Technology development for enlargement of wind turbine is possible not only the improvement of energy efficiency but also reduce the construction costs per unit capacity. However, mechanical gearboxes used in wind generators have problems of wear, damage, need for lubrication oil and maintenance. Therefore, we want to configure the gearbox of a large-scale wind turbine using a magnetic gear in order to solve these problems of mechanical gearbox.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.633-635
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• 2007

To cope with increasing power demand in metropolitan area, the power system in Korea has equipped with unit generator of large capacity, high density and uneven distribution, and transmission line of long distance, large capacity and high voltage. As the power system growing up enormous, it has become difficult to maintain the standard voltage in case of radical fluctuation of load or severe change of voltage by power system fault for its weakness of responsive characteristics although the power condenser has been installed to solve the unstability by lack of reactive power. Consequently, we review harmonic wave production and control characteristics to solve unstability problem of voltage in northern metropolitan, to reduce transmission restriction cost and to minimize load shedding by relocation of SVC (Static Var Compensator), which is highly effective for improvement of responsive characteristics for radical voltage fluctuation.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.3-5
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• 2005

The overhang parameter is required to maximize the power density of generator. However, the use of overhang design causes the rise of material cost. Moreover there is somewhat different overhang effect according to the rotor types. This paper presents the overhang effect on the overhang length according to the rotors with permanent magnet of generators. To examine the phenomenon of overhang effect, the new dynamic analysis method with 2D FEM is suggested and verified by the test results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.209-214
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• 2005

In this paper, finite element simulation of three-dimensional bulk metal forming processes is performed by an automated adaptive tetrahedral mesh generation scheme. A dynamic data exchange scheme is employed between tetrahedral mesh generator and forging simulator to minimize user intervention. Both number of elements and density distributions are controlled by the octree technique. The presented approach is applied to automatic forging simulation in order to evaluate the efficiency of the developed schemes and the simulation results are compared with $DEFORM^{TM}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.741-744
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• 2004

In concrete pavements with uniform tining space, the whine noise which has high frequency spectrum related to the uniform tining space exist. In this paper, randomization procedure of tining space for concrete pavements is proposed. The proposed procedure developed based on the LCG(Linear Congruential Generator) algorithm. And the factor concerned in the procedure are drag span length, number of different tining space, ratio of each tining space, total tinings of each size, sequence of actual tining.

• Progress in Superconductivity and Cryogenics
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• v.12 no.2
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• pp.13-16
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• 2010

The superconducting synchronous motor or generator mostly has high permeability iron only around outer yoke portion. Therefore, if excitation voltage (Back E.M.F) is calculated from 2 dimensional magnetic field distributions, it can be largely different from actual value due to additional voltage originated from end coils. In order to calculate the excitation voltage more accurately, 3 dimensional magnetic field calculation is necessary for including the end coil effect from large air-gap structure. The excitation voltage can be calculated by stator (armature) coil linkage flux originated from rotor (field) coil excitation, but it is difficult to calculate the flux linkage exactly because of complicated structure of the stator coil. This paper shows a method to calculate the excitation voltage from 3 dimensional magnetic energy that can be calculated directly from volume integration of magnetic flux density and field intensity scalar product through FEM (Finite Element Method) analysis software.