• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.242-247
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• 2013

In order to prepare for weakening of the productivity of agriculture due to serious climate change, the researches on promoting the growth of plant are required. Although the method of using magnetic field for improving the growth of plant was introduced, the effective method of imposing the field on the plant have yet to be studied thoroughly in the literatures. In this paper, we investigated the effects of static magnetic field on the growth and the early seed germination of radish sprouts according to the strength, direction of excitation and the expose time of the magnetic field, and present the effective method of imposing magnetic fields. From the measurements, it was found that the radish sprouts exposed in the field shows a rapid germination of about 3~4 days than those which had no field, and in order to the effective growth, the strength of the magnetic field should be properly selected, and the excitation direction of magnetic field has little effect on the radish sprouts growth.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1776-1779
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• 2002

In this paper, we measured the heating time on the key measuring point of the meridian of the human body's left and right by using heating machine. Then, based on the fuzzy theory, this study diagnosed the each meridian's strength and weakness, After that, both the strengthening and weakening stimulus of magnetic field was applied to the dominant direction to find out how the degree of strength and weakness of the meridian changed. Ultimately, the magnetic therapy that can stimulate the magnetic field at the time of diagnosis and thereby balancing the interactive of a five system has been materialized. For the stimulation of magnetic field, a stimulating device which can change the direction and time on a specific part of the key measuring points has been developed and used. The therapeutic method is as follows. first, the strength and weakness of the meridian has been determined. Second, both the extremely weak meridian of Yin(Shade) and Yang(Shine), and the extremely strong meridian of Yin and Yang were adjusted by applying appropriate ascending and descending stimuli respectively.

• Journal of Labour Economics
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• v.41 no.1
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• pp.83-124
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• 2018

In this study, with the data of Human Capital Corporate Panel(HCCP) we find that the explaining power of the new hiring rate of experienced regular workers is very strong and statistically significant as a main causal factor to the decreasing trend of investment on education and training for workers in corporates, which means a sign of weakening of the internal labor market. Possibility of wage penalty from switching jobs has been weakened considerably too. The effective alternative policy measures to the weakening or laxity of the internal labor markets and whereby followed reduction in investment on education and training for workers in corporates are construction of social system outside of individual corporates to upbring field-tailored manpower of high quality for young generations and small and medium sized enterprises.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.4
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• pp.211-216
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• 2004

Inductance characteristics, torque variations and ripple according to current, and position of multi-layer buried magnet synchronous machines with field-weakening operations are presented. The rotor structure optimal design of a buried magnet synchronous machine with high performance is investigated, and optimization results and comparison among design candidates are shown. For the fast and accurate search of multiple optima, the auto-tuning niching genetic algorithm is used and a final solution is selected considering various design factors.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1473-1479
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• 2011

In this paper, speed control of IPMSM drives for the next generation domestic high speed railway system using multilevel inverter is presented. Multilevel inverter is suitable for the high-voltage high-capacity motor drive system because noise and switching frequency of power semiconductor devices is reduced. For the speed control of IPMSM using multilevel inverter, maximum torque control is applied in a constant torque region, and field weakening control is applied in a constant power region. Simulation programs based on Matlab/Simulink are developed. Finally the designed system is verified by simulation and their characteristics are analyzed by the simulation results.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.1-11
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• 1996

The rotor flux level need be changed frequently for field weakening or power efficiency control. Motor inductances depend on rotor flux but not on machine temperature. On the other hand, rotor resistance varies greatly with the machine temperature. Motor parameters such a sinductances and rotor resistance should be known precisely in order to attain high dynamic performance of inductin motor. In this paper, efficient an dnovel identification algorithms for motor inductances and rotor resistance are presented. The rotor flux is changed. As the result, the slip frequency is varied. The identificatin algorithm for rotor resistance measures the varied slip frequency and alters the estimated rotor resistance. Then, the estimated value of rotor resistance will approach its real value. The proposed identification algorithms are computationally simple and have very small identification errors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.391-397
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• 2018

This paper proposes a interpolation error compensation method for PMSM torque control. In PMSM torque control, two dimensions look-up table(2D-LUT) is used for current reference generation due to its stable and robust torque control performance. However, the stored data in 2D-LUT is discreet, it is impossible to store all over the operation range. To reduce the reference generation error in this region, the 2D-Interpolation method is conventionally used, however, this method still remains the error affected by the number of stored data. Besides, in the case stored by fixed unit, this error is increased in field weakening region because of the small number of stored data. In this paper, analyzing the cause of this interpolation error, and compensating the method to reduce this error. Proposed method is verified by the simulation and experiment.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.448-452
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• 2001

This paper describes the nonlinear sensorless control of induction motor by using feedback linearization and current error; the feedback linearization technique and the current error are applied for independent between rotor flux and electric torque and for speed estimation. The dynamic characteristics of the proposed nonlinear control algorithm involving field weakening area are verified by simulation and experiment.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.985-986
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• 2011

This paper deals with d-q axis equivalent circuit analysis of IPMSM(Interior Permanent Magnet Synchronous Motors) considering voltage harmonics. In the field weakening region, as the current vector angle increased, back-emf contains large harmonics, therefore, significant underestimation of voltage or overestimation of speed can be occurred from the conventional d-q axis equivalent circuit analysis. In order to consider the effects of voltage harmonics, a harmonic coefficient is introduced and verified by experiments.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.586-588
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• 2008

농형 유도전동기의 센서리스 벡터제어시 기존의 약계자 알고리즘은 오토튜닝 오차에 의해 자속기준값이 크게 계산되어질 때 역기전력과, 전압제한값에 의해 최대전류를 출력할 수 없다. 본 논문에서는 약계자 영역에서 토크분 전류제어 오차를 이용하여 자속 기준값을 보상함으로써 전류부족에 의한 속도강하를 방지하는 알고리즘을 소개하였고, 시뮬레이션을 통해 그 타당성을 검증하였다.