• Communications of the Korean Mathematical Society
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• v.8 no.4
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• pp.569-578
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• 1993

• Bulletin of the Korean Mathematical Society
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• v.26 no.1
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• pp.95-95
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• 1989

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.875-880
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• 2016

A new hybrid permanent magnet biased magnetic levitation actuator (maglev) is developed. This new maglev actuator is composed of two C-core electromagnetic cores separated with two permanent magnets. Compared to the conventional hybrid maglev actuators, the new actuator has unique flux paths such that bias flux paths are separated with control flux paths. The control flux paths have minimum reluctances only developed by air gaps, so the currents to produce control fluxes can be minimized. The gravity load can be compensated with the permanent magnet bias fluxes developed at off-centered air gap positions while external disturbances are controlled with control fluxes by currents. The consumed power to operate this levitation system can be minimized. 1-D magnetic circuit model is developed for this model such that the flux densities and magnetic forces are extensively analyzed. 3-D finite element model is also developed to analyze the performances of the maglev actuator.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.36-42
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• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.

• Land and Housing Review
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• v.15 no.1
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• pp.23-38
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• 2024

This study examined the residential environment of public rental housing by type at a microscale, using ANOVA and multinominal logistic models, based on the minimum and specific housing standards. The key findings are as follows. First, it was confirmed that each type of public rental housing, as well as resident characteristics, varied in meeting the minimum and specific housing standards. Second, Happy House turned out to have the worst residential environments, as a high proportion of this type did not meet the minimum housing standard and the remaining specific standards, excluding facility standards. Third, among permanent rental, national rental, and purchase/jeonse rental housing types, permanent rental housing was poor by the minimum housing standards, and area and room standards, while purchase and jeonse rental housing types showed a high proportion of failure to meet structural, performance, and environmental standards. Fourth, it was confirmed that purchase/jeonse rentals had higher rental anxiety than other types of public rental housing. In particular, anxiety about rent increases and the loss of deposits was high. These findings suggest that public efforts are called for to improve the residential environment through tailored support, depending on the type of public rental housing.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.66-68
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• 2003

This paper is deal with the method of design for the optimum model using genetic algorithms in slotted Permanent Magnet Linear Synchrous Motor (PMLSM). The objective functions are maximum thrust and minimum detent force. Characteristic analysis method is used 2D space harmonic analysis method. Design parameters are PM width, PM height and slot width.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.3
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• pp.112-119
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• 2001

This paper proposes an adaptive reclosing scheme which is based on the classification of fault patterns. In case that the first reclosing is unsuccessful in distribution system employing with two-shot reclosing scheme, the proposed method can determine whether the second reclosing will be attempted of not. If the first reclosing is unsuccessful two fault currents can be measured before the second reclosing is attempted, where these two fault currents are utilized for an adaptive reclosing scheme. Total harmonic distortion and RMS are used for extracting the characteristics of two fault currents. And the pattern of two fault currents is respectively classified using a mountain clustering method a minimum-distance classifier. Mountain clustering method searches the cluster centers using the acquired past data. And minimum-distance classifier is used for classifying the measured two currents into one of the searched centers respectively. If two currents have the different pattern it is interpreted as temporary fault. But in case of the same pattern, the occurred fault is interpreted as permanent. The proposed method was tested for the fault data which had been measured in KEPCO's distribution system, and the test results can demonstrate the effectiveness of the adaptive reclosing scheme.

• Bulletin of the Korean Mathematical Society
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• v.41 no.2
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• pp.199-211
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• 2004

For positive integers $\kappa$ and p$\geq$3, let(equation omitted) where $J_{p}$ is the p${\times}$p matrix whose entries are all 1. Then, we determine the minimum permanents and minimizing matrices over (1) the face of $\Omega$(D) and (2) the face of $\Omega$($D^{*}$), where (equation omitted).

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.7
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• pp.323-328
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• 2005

This paper is proposed maximum thrust design of slotted permanent magnet linear synchronous motor(PMLSM) using surface harmonic method(SHM) considering slot effect. The genetic a1gorithm is used for optimization. The functional are selected the maximum thrust and the minimum detent force. This time. design parameters are set as permanent magnet(PM) width. PM height and slot width. Thrust is increased from 272[N] to 295[N] and detent force is decreased from 5[N] to 2.43[N] greatly in optimum design. Therefore, thrust ripple isn't generating almost. Also, the results of 2D EMC considering slot-effect are compared with ones of experimental and finite element analysis..

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.621_622
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• 2009

This paper presents an efficient calculation method for torque and torque ripple of a permanent magnet synchronous motor by using superposing method of load angle torque curves from finite element method. The load angle range having minimum torque ripple as well as average torque according to load angle can be induced by proposed method. We selected a permanent magnet assisted synchronous reluctance motor (PMa-SynRM) as a study model because of its high torque ripple. We performed experiment of torque ripple and average torque according to load angle for the verification of proposed method in the paper.