• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.48-56
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• 2007

In this paper, the rotor losses in high-speed permanent synchronous motor (PMSM) considering the operating condition are discussed. In order to maintain the mechanical integrity of a high-speed permanent magnet machine rotor intended for high-speed operation, the rotor assembly is often retained within a stainless steel or Carbon-Fiber/Epoxy sleeve. The sleeve is exposed to fields produced by the stator from either the slotting or the mmf harmonics that are not synchronous with rotor losses. On the basis of analytical field analysis, the rotor losses are analyzed. In particular, the no-load, rated with air-cooled, and forced water cooled conditions are considered. The results are validated extensively by comparison with non-linear finite element method (FEM).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.699-704
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• 2007

In this paper, optimized model was designed for the starting characteristic of the Single-Phase Line-Start Permanent Magnet Synchronous Motor by using the Design of Experiment. A field pole angle, thickness and distance from center axis of permanent magnet were selected as design factor. We executed the transient state characteristic analysis of 8 test models. The transient state characteristic analysis was executed by using the 2 dimensional Finite Element Method and the Time Difference Method. We checked the fact that the selected design factor affected starting characteristic of the Line-Start Permanent Magnet Synchronous Motor. Depend on this result we found the optimized design point by using the response optimization.

• Journal of Labour Economics
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• v.38 no.2
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• pp.25-58
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• 2015

This paper compares income and consumption inequalities in Korea and applies the permanent income hypothesis to interpret the linkage between the two inequalities. Income inequality has been increasing since 1990 while consumption inequality had been decreasing until the early 2000s when the two inequalities started to co-move. Permanent income hypothesis explains reasonably well the consumption pattern in the recent period, which reflects the increased access to asset markets by the Korean households. Consequently, the co-movement of income and consumption inequalities in the recent period implies that inequality in permanent income components are fluctuating.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.125-132
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• 2013

This paper has done a three-dimensional FEM analysis of the PM claw pole stepping motor. As magnetization happens in the z-axis, which does not have a constant value, three-dimensional FEM analysis is necessary for characteristic analysis of PM claw pole stepping motors. Because it is a type of permanent magnet motor, the PM claw pole stepping motor naturally has a detent torque. This torque is known to show negative effects on motor performance. To improve motor performance, reducing the detent torque is very important during the motor design. This paper applied DOE for optimization of stator pole design of the motor. Also, we compared motor performance by applying a different type of rotor shape, dividing the permanent magnet. To verify the simulation results, an experiment was done.

• Journal of the Korean Institute of Rural Architecture
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• v.11 no.3
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• pp.37-44
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• 2009

There is a rapid increase of child care centers due to the growth of women's social activities and a nuclear family. Child care center is an important part of community facilities for apartment housing complex. This study aims to collect the basic data required to develop the planning standards for the child care centers. This research limited the child care centers which is situated to permanent rental housing complex. Therefore, this research presents the basic design guidelines for the space composition planning of child care centers by grasping the special quality connected with the space composition of child care centers among the community facilities that is located in the permanent rental apartment housing complex.

• Journal of Power Electronics
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• v.12 no.4
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• pp.604-614
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• 2012

This paper presents a comparative study of position sensorless control schemes based on back-electromotive force (back-EMF) estimation in permanent magnet synchronous motors (PMSM). The characteristics of the estimated back-EMF signals are analyzed using various mathematical models of a PMSM. The transfer functions of the estimators, based on the extended EMF model in the rotor reference frame, are derived to show their similarity. They are then used for the analysis of the effects of both the motor parameter variations and the voltage errors due to inverter nonlinearity on the accuracy of the back-EMF estimation. The differences between a phase-locked-loop (PLL) type estimator and a Luenberger observer type estimator, generally used for extracting rotor speed and position information from estimated back-EMF signals, are also examined. An experimental study with a 250-W interior-permanent-magnet machine has been performed to validate the analyses.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.26-32
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• 2013

Passive attitude stabilization method has been widely usde for attitude determination and control of cube satellite due to its advantage of system simplicity. The permanent magnet installed on the cube satellite passively controls the attitude of the satellite such that the satellite is aligned with the earth magnetic field. In this paper, on-orbit thermal behavior of the cube satellite with the permanent magnet attitude stabilization method has been investigated through on-orbit thermal analysis. THe orbit profile obtained from the aforementioned attitude control method has been reflected in the analysis. The analysis results indicate that the thermal design proposed in this study is effective for satisfying the temperature requirements of the commericial mission equipments.

• Journal of Magnetics
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• v.19 no.4
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• pp.411-417
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• 2014

This paper presents the shape optimization of a permanent magnet synchronous motor to reduce the torque ripple and iron loss. Specifically, the harmonics of the electromotive force and cogging torque are decreased by adjusting the permanent magnet arrangement and non-uniform air gap length. In addition, an additional flux path along the q-axis is proposed with a unique rotor shape to increase the q-axis inductance and reluctance torque. The improvement in the performance of the proposed model is verified with simulated and experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.475-480
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• 1999

Recently domestic building market in the face of 3D, in addition to construction cost increase, materials lack problems and opening a building market to foreign countries, is trying to find out the efficient ways of overcoming these problems. So the necessity to study the permanent form is urgent to escape the problems of constructing human power economy, cost down, noises problem, environmental prevention and efficacy of form work to technical improvement will contribute a practical permanent form in field through economic evaluation of permanent form. In this paper, we compared wood form cost with permanent form cost(made form polymer or fly ash) for frame work

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.189-196
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• 2004

In this study, the colloidal silica grouts (PSG) with novel chemical compositions for permanent reinforcement and water cut-off of the ground were prepared and their engineering charateristics were investigated. The optimum mixing recipes for both homogeneous solution grouts and heterogeneous suspension grouts were investigated and established through many repeated lab tests. The various physical properties(such as compressive strength, durability and syneresis) of the grout gels derived from the colloidal silica were investigated and compared with those of the well-known existing watergalss grouts. The all experimental results showed that the novel colloidal silica grouts(PSG) had greatly excellent performances as permanent grouts, especially in comparison with the existing watergalss grouts.