• Journal of KSNVE
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• v.10 no.5
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• pp.886-891
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• 2000

In this paper, an iterative array shape estimation technique is presented, which is based on the use of the least squares polynomial fitting to the data from heading sensors. The estimated polynomial shape model is then used for calculating the hydrophone positions on the assumption that the arc distances between sensors are constant. In order to verify the applicability of the proposed algorithm, numerical simulations are performed using two types of non-linear array shapes. In addition the noise effects of heading sensors on the array shape estimation results and the performance of beamformer are also investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.792-800
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• 2021

This paper presents a new structure for a linear active magnetic bearing using a Halbach magnet array. The proposed magnetic bearing consisted of a Halbach magnet array, center magnet, and single coil. The proposed linear active magnetic bearing has a high dynamic force compared to the previous study. The high dynamic force could be obtained by varying the thickness of a horizontally magnetized magnet. The new structure of Halbach linear active magnetic bearing has a high dynamic force. Therefore, the proposed linear active magnetic bearing increased the bandwidth of the system. Magnetic modeling and optimal design of the new structure of the Halbach linear active magnetic bearing were performed. The optimal design was executed on the geometric parameters of the proposed linear active magnetic bearing using Sequential Quadratic Programming. The proposed linear active magnetic bearing had a static force of 45.06 N and a Lorentz force constant of 19.54 N/A, which is higher than previous research.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.87-92
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• 2002

A short-ended electromagnetically coupled coaxial dipole array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are obtained by solving the simultaneous linear equations. The effects of slot and strip numbers on the radiation efficiency, beamwidth and directivity gain of the antenna are presented.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.154-161
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• 2005

In the machine tool industry, direct drive linear motor technology is an interesting means to achieve high acceleration, and to increase reliability. This paper analyzes and compares the characteristics of a tubular linear motor with Halbach and radial magnet array, respectively. First, the governing equations are established analytically in terms of the magnetic vector potential and two dimensional cylindrical coordinate systems. Then, we derive magnetic field solutions due to the PMs and the currents. Motor thrust, flux linkage and back emf are also derived. The results are shown to be in good conformity with those obtained from the commonly used finite element method. Finally, control parameters are obtained from analytical solutions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.739-748
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• 1992

A CGM iterative systolic algorithm to solve large sparse linear systems of equations is presented. For implementation of the algorithm, a systolic array using the stripe structure is proposed. The matrix A is decomposed into a strictly lower triangular matrix, a diagonal matrix, and a strictly up-per triangular matrix, and the two formers and the tatter· are concurrently computed by different linear arrays. Hence, the execution time of this approach Is reduced to half of the execution time of the that a linear array is used. computation of the Irregularly distributed sparse matrix can be executed effectively by using the stripe structure.

• Journal of Magnetics
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• v.21 no.1
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• pp.110-114
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• 2016

Magnetic couplings are widely used in various industrial applications because they can transmit magnetic force without any mechanical contact. In addition, linear couplings have many advantages. For example, they do not need to convert rotary motion to linear motion. This paper shows an analytical analysis of tubular type linear magnetic couplings (TLMCs) with a Halbach array magnetized permanent magnet (PM). An analytical method for magnetic fields owing to PMs is performed by using magnetic vector potential as well as Poisson and Laplace equations. Then, the magnetic force is calculated by using the Maxwell stress tensor. The analytical analysis results were compared with finite element method (FEM) results. In addition, we predicted the magnetic force characteristic according to design parameters such as the iron core thickness, inner PM thickness to -outer PM thickness ratio, PM segment ratio of the axial magnetized PM segment and radial magnetized PM segment, and various pole numbers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.503-504
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• 2010

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.39-49
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• 2013

The effect of the finite substrate size on the radiation characteristics of H-plane linear microstrip array antennas is investigated. The radiation characteristics versus scan angle are systematically analyzed for 5-element H-plane linear array antennas with various substrate sizes and element spacings for the substrates with different dielectric constants. The distance between the antenna center and the substrate edge on the E-plane for the enhancement of the radiation characteristics of the array antenna is presented.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.46-53
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• 2011

The effect of a finite substrate on the radiation characteristics of a linear 7-element array antenna positioned along the E-plane is investigated. Active reflection coefficients and average active element patterns are simulated for various substrate sizes. The E-plane radiation pattern of a fully excited array for various scan angles is correlated with the active reflection coefficient and average acitive element pattern. The effect of E-plane substrate size on the radiation characteristics of a linear array along the E-plane is larger than that of H-plane substarte size.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1132-1138
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• 2011

In this paper, a method for synthesizing the linear antenna array patterns with broad nulls(BN) at the interference directions is newly presented. Opposit to the conventional methods in which the weights of array elements are optimized for BN control, this method simplifies the control process for multiple BN directions and widths by optimally perturbing the zero positions inherent to Schelkunoff polynomial transformed from the array factor. It is also shown that this method can be easily applicable to the phased array antennas. The proposed scheme is numerically verified by substituting the extracted complex weights into the array factor.