• Title, Summary, Keyword: Average torque

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A Comparison of Muscle Strength by Russian Current and Low Frequency Current Stimulation in Normal Adult (정상성인에서 러시안 전류와 저주파 전류 자극에 의한 근력 증가의 비교)

  • Kim, Jong-Youl
    • Journal of the Korean Society of Physical Medicine
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    • v.6 no.3
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    • pp.353-360
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    • 2011
  • Purpose : The purpose of this study was to compare the effect of muscle strength by stimulation of russian current and low frequency. Methods : The subjects were thirty young healthy volunteers who were divided into two groups including russian current group(n=15) and low frequency group(n=15). The intervention was applied totally 12 times (1 time, 10 minute) for 4weeks in each group. The peak torque and average power were measured and analysed using Biodex system 4 before the treatment, after 2 weeks, 4 weeks. Results : As a result, russians currents and low frequency stimulation increased significantly average power and peak torque with the lapse of time. However, there were not significant differences of the average power and peak torque between the groups in all periods. Conclusion : In conclusion, russians currents and low frequency stimulation had no differences in the increase of muscle strength.

Improvement of Torque Characteristics of a Rotatory Two-phase Transverse Flux Machine Optimizing the Shape of Rotor Pole (자석 형상 최적화를 통한 축방향 이상 횡자속형 전동기의 토크 특성 향상에 관한 연구)

  • Ahn, Hee-Tae;Jang, Gun-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.10
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    • pp.1003-1011
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    • 2009
  • Transverse flux machine(TFM) has been developed to drive a machine of large input power at low-speed. However, it has complicated structure and large torque ripple due to its inherent structure. In this paper the characteristics of torque of a rotatory two-phase TFM are analyzed by using the 3-dimensional finite element method and optimal design. This research shows that one of the effective design variables is the skew angle of permanent magnet. The skew angles of permanent magnet are optimized by using a genetic algorithm. It also shows that the proposed optimal skew magnet not only increases average torque but also decreases torque ripple of a rotatory two-phase TFM.

Study of Permanent Magnet Optimum Design on the Permanent Magnet assisted-Synchronous Reluctance Motor

  • Lee, Hyung-Woo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.11
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    • pp.28-33
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    • 2009
  • Average torque of PMa-SynRM(Permanent Magnet-assisted Synchronous Reluctance Motor) is changed by magnet form inserted to the barrier. Because the magnet structure inserted to the barrier influences to the magnet-torque and reluctance torque. Therefore, this paper present a suitable permanent magnet form design for maximum torque when the magnet quantites are always fixed. And each motor characteristic such as average torque, torque ripple, cogging torque and back-EMF are analyzed by FEM(Finite Element Method) for optimal design.

Study of Permanent Magnet Optimum Design on the PMa-SynRM (PMa-SynRM에서 영구자석 배치에 따른 최적 설계 연구)

  • Kim, Su-Yong;Kim, Won-Ho;Im, Jong-Bin;Lee, Ki-Deok;Ryu, Gwang-Hyeon;Lee, Ju
    • Proceedings of the KIEE Conference
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    • pp.768_769
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    • 2009
  • Average torque of PMa-SynRM(Permanent Magnet-assisted Synchronous Reluctance Motor) is changed by magnet form inserted to the barrier. Because the magnet form influences to the magnet-torque and reluctance torque. Therefore, this paper present a suitable permanent magnet form design for maximum torque when the magnet quantites are always fixed. And each motor characteristic such as average torque, torque ripple, cogging torque and back-EMF are analyzed by FEM(Finite Element Method) for optimal design..

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An Asymmetric Rotor Design of Interior Permanent Magnet Synchronous Motor for Improving Torque Performance

  • Yoon, Myung-Hwan;Kim, Doo-Young;Kim, Sung-Il;Hong, Jung-Pyo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.387-393
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    • 2015
  • Torque ripple is necessarily generated in interior permanent magnet synchronous motors (IPMSMs) due to the non-sinusoidal distribution of flux density in the air gap and the magnetic reluctance by stator slots. This paper deals with an asymmetric rotor shape to reduce torque ripple which can make sinusoidal flux density distribution in the air gap. Meanwhile the average torque is relatively increased by the asymmetric rotor. Response surface method (RSM) is applied to find the optimum position of the permanent magnets for the IMPSM with improved torque performance. Consequently, an asymmetric structure is the result of RSM and the structure has disadvantage of a mechanical stiffness. Finally, the performance of suggested shape is verified by finite element analysis and structural analysis is conducted for the mechanical stiffness.

In-process Immersion Ratio Estimation Using Spindle Motor Current during Face Milling (정면밀링공정중 추축모터전류를 이용한 절입비의 실시간 추정)

  • 조규진;오영탁;권원태;주종남
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.57-64
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    • 2000
  • In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ratio using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to the cutting torque acting on a single tooth at the swept angle of cut and can be acquired from cutting torque signals. Average cutting torque per revolution can also be calculated from cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current. Varying immersion ratio is also estimated well using the presented algorithm.

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Immersion Ration Estimation Using Spindle Motor Current during Milling (밀링공정에서 주축모터전류를 이용한 절입비 추정)

  • Cho, K.-J.;Kwon, W.-T.;Cho, D.-W.;Chu, C.-N.
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.12
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    • pp.222-229
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    • 1999
  • In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ration using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to cutting torque acting on a single tooth at the swept angle of cut and can be acquired form cutting torque signals. Average cutting torque per revolution can also be calculate form cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current.

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New Phase Energization Strategies for the Minimization of Hybrid Step Motor Torque Ripples (하이브리드 스텝모우터의 토오크 리플 최소화를 위한 새로운 상여자방식)

  • Kim, Yoon-Ho;Yoon, Byung-Do;Eum, Tae-Wook
    • Proceedings of the KIEE Conference
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    • pp.133-136
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    • 1991
  • New phase-energization strategies are proposed to minimize torque ripple of closed-loop controlled 2-phase Bifilar Hybrid step motors. Lead angle and conduction angles are important parameters in minimizing torque ripple factors. The phase-energization control strategy that minimizes torque ripples for the given average torque is proposed. In this paper, Fourier series are applied to produce the average torque. The strategy is performed by controlling both lead angle and conduction angle of the input voltage wave-form for each phase.

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Optimum Geometric and Electrical Parameter for Minimization Torque Ripple of Switched Reluctance Motor (스위치드 릴럭턴스 전동기의 토오크 리플 저감을 위한 기하학적인 파라미터와 전기적인 파라미터의 최적화)

  • Choi, Jae-Hak;Kim, Sol;Lee, Kab-Jae;Lee, Ju;Hong, Kyung-Jin;Choi, Dong-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.3
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    • pp.93-100
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    • 2003
  • Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

The Effects of Different Angles of Wedged Insoles on Knee Varus Torque in Healthy Subjects

  • Jung, Do-Young;Kwon, Oh-Yun;Yi, Chung-Hwi;Kim, Young-Ho;Kim, Jang-Hwan
    • Physical Therapy Korea
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    • v.11 no.4
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    • pp.31-41
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    • 2004
  • The purpose of this study was to examine the effect of the angle of a wedged insole on knee varus torque during walking. Fifteen healthy subjects were recruited. Knee varus torque was measured using three-dimensional motion analysis (Elite). Knee varus torque was normalized to gait cycle (0%: initial contact; 100%: ipsilateral initial contact) and stance phase (0%: initial contact; 100%: ipsilateral toe off). The average peaks of knee varus torque during the stance phase of the gait cycle according to the different insole angles (10 or 15 degrees) were compared using one-way ANOVA with repeated measures. The results showed that in the early stance phase, the average peak knee varus torque increased significantly for both the medial 10 and 15 degree wedged insole conditions and decreased significantly for both the lateral 10 and 15 degree wedged insole conditions as compared with no insole (p<.05). However, there were no significant differences between the 10 and 15 degree wedged insole conditions with either the medial or lateral wedged insole (p>.05). In the late stance phase, the average peak knee varus torque increased significantly for the medial 10 and 15 degree wedged insole conditions (p<.05), but not for the lateral 10 and 15 degree wedged insole conditions as compared with no insole (p>.05). We suggest that these results may be beneficial for manufacturing foot orthotic devices, such as wedged insoles, to control medial and lateral compartment forces in the knee varus-valgus deformity. Further studies of the effects of wedged insole angle on knee varus torque in patients with medial-lateral knee osteoarthritis are needed.

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