• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.551-557
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• 2006

The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.610-614
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• 2000

Torque pulsation generated in every commutation period is the main drawback of BLDC motor which deteriorates the precision of BLDC motor. Many methods to solve this problem have been proposed. In this paper a new torque model considered with decaying phase back EMF is introduced and from it the cause of torque pulsation in commutation period is analyzed. Form this analysis new algorithms to reduce the torque pulsation by commutation time are proposed and with simulation the validity is verified.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.657-682
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• 2011

This paper presents the dynamic analysis on the joint torque of a finger for the tip pinch task. The dynamic model on finger movement was developed in order to predict the joint torques of an index finger, and the finger was assumed as a three-link planar manipulator. Analysis of the model revealed that the joint stiffness was one of the most important parameters affecting the joint torque. The stiffness of the finger joint was experimentally measured, and it was used in analyzing the finger joint torque required for performing the tip pinch task. The obtained joint torque for the tip pinch task will be used as the design requirements of the finger exoskeletal orthosis actuated by the polymer actuator whose allowable torque limit is relatively low compared to that of a mechanical actuator.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.8-13
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• 2016

Purpose: The aim of this study was to compare the accuracy of two different styles of mechanical implant torque wrenches before and after sterilization and repeated use. Materials and methods: Thirty new spring-style and friction-style mechanical implant torque wrenches from five different manufacturers were selected as subjects of study and assessed in terms of accuracy. Three manufacturers produced, spring-style (Dio, Neobiotech, Osstem) torque wrenches, and other three manufactures produced friction-style (Dentium, Osstem, Shinhung) torque wrenches. The procedure of target torque measurement was performed 10 times for each device and a digital torque gauge (MGT-12, Mark-10 Corp, USA) was used to record the measurements. All torque wrenches were used repeatedly for 20 times and then sterilized. This whole procedure was repeated 100 times and all torque wrenches were retested. The collected data was analyzed using a SPSS Statistics Analysis program to evaluate the accuracy of the torque wrenches and Mann-Whitney-U test was used for a comparative analysis. Results: After sterilization and repeated use procedure, results did not show any significant difference between error values in the spring-style torque wrench group. However, the results demonstrated an increase in error values within the friction-style torque wrench group (P<.05). Conclusion: There was no difference between the accuracy of new spring-style torque wrenches before and after 100 cycles of sterilization and repeated use (P>.05). There was significant difference between the accuracy of new friction-style torque wrenches before and after 100 cycles of sterilization and repeated use (P<.05). Within the limitation of this study, spring-style torque wrenches were more accurate than friction-style torque wrenches in delivering target torque values.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.26-31
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• 2011

In this paper, torque characteristics analysis of Synchronous Reluctance Motor with the cylindrical rotor type by winding function theory(WFT) is described. The stator is same as one of the induction motor. From the d-axis, q-axis flux density distribution, to calculate self and mutual inductances needed to calculate the torque of the machine by using winding function theory the new equivalent geometry of rotor was proposed. D-axis, q-axis flux densities, self inductance and torque characteristics were obtained. From the comparison with results of finite element analysis the proposed method was verified.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.103-110
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• 2000

In this study, the angular twist type torque-meter was designed and manufactured with STS 304 and fiber-reinforced composite materials to improve the dynamic properties of the existing torque-meter. From the Experimental and analytical results, it was found that the dynamic characteristics of co-cured bonded torque-meter rotating shaft were better than those of the adhesively and unreinforced torque-meter rotating shaft. For the torque-meter rotating shaft manufactured by co-cured bonded with the glass fiber-epoxy composite and with a stacking sequence of $[$\pm$30$^{\circ}$/STS304]_{2s}$, the natural frequency and the radial spring constant were increased by 64% and 137% compared to those of the unreinforced torque-meter rotating shaft.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.393-397
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• 1996

A stewart platform-based force/torque sensor with 6 elastic legs was designed and manufactured Kinematic design parameters were determined so that the force/torque sensor might have the isotropic force/torque properities. In a force/torque analysis, it was used the solution of forward kinematics by linearization of the solution of the inverse kinematics. The performance of te force/torque sensor was investigated by measurement experiments. The gravity compensation was conducted to reduce the force and torque effects by the weights of the upper plate, joints and other sensor parts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.785-790
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• 2011

This paper presents the effects of an assisting motor torque ripple on a driver's steering feeling using a simulink. The EPS(Electric Power Steering) System is modeled as a 5 degrees of freedom for simulation. To find out the influence of a torque ripple on a driver's steering feeling, which is the purpose of this study, we observed the assisting torque in various different speeds, when the torque ripple increased by 0%~40%. The torque ripple had a small but definite influence on the assisting torque, and it had a greater influence in low speeds rather than high speeds.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.85-89
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• 2012

This paper presents a study on the system identification of the in-situ output shaft torque measurement system using a non-contacting magneto-elastic torque transducer installed in a vehicle drivline. The frequency response (transfer) function (FRF) analysis is conducted to interpret the dynamic interaction between the output shaft torque and road side excitation due to the road roughness. In order to identify the frequency response function of vehicle driveline system, two power spectral density (PSD) functions of two random signals: the road roughness profile synthesized from the road roughness index equation and the stationary noise torque extracted from the original torque signal, are first estimated. System identification results show that the output torque signal can be affected by the dynamic characteristics of vehicle driveline systems, as well as the road roughness.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.705-710
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• 2004

In the present study, a transient incompressible viscous turbulent flow is simulated for the automotive torque converter with moving mesh technique. For the analysis, entire torque converter flow passages are modeled. Computed torque ratio, capacity factor and efficiency show a good agreement with the experiment data. The flow instabilities characterized by back-flow and wake etc. appeared in some cascade passages are shown to be Propagating along tangential direction. These flow patterns are mainly influenced by the pump and turbine blade passing and can't be predicted through conventional steady simulation with a mixing plane approach. The understanding of the unsteady flow characteristics in a torque converter achieved in the present study may lead to the optimal design of a torque converter.