• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.227-237
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• 2007

Various methods and torque generating devices are developed and employed to apply proper torque clinically. In this study, clinically used torque control devices are measured whether uniformed and precise torque are generated. Digital torque gauge are employed for measurement and torque driver, torque limiting device, torque indicating device are used for torque generating devices. ${\chi}^2$ distribution was formed and One-way ANOVA(Turkey test) was performed to measure torque values generated by each torque generating device. In the results, all companies have been shown slight errors and deviations. This indicates a difficulty of applying precise torque. Therefore, it would be recommended torque generating device should be checked whether uniformed and precise torque can be generated and an error should be corrected.

• Journal of Power Electronics
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• v.13 no.6
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• pp.964-974
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• 2013

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.155-162
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• 2006

It is necessary to monitor periodically the operability of safety-related motor-operated valves (MOVs) in nuclear power plants. However, acquiring diagnostic signals for MOVs is very difficult, and doing so requires an excessive amount of time, effort, and expenditure. This paper introduces an accurate and economical method to evaluate the performance of MOVs remotely. The technique to be utilized includes electrical measurements and signal processing to estimate the motor torque and the stem thrust, which have been cited as the two most effective parameters in diagnosing MOVs by the US Nuclear Regulatory Commission. The motor torque is calculated by using electrical signals, which can be measured in the motor control center (MCC). Some advantages of using the motor torque signature over other signatures are examined. The stem thrust is calculated considering the characteristics of the MOV and the estimated motor torque. The basic principle of estimating stem thrust is explained. The developed method is implemented in diagnostic equipment, namely, the Motor Operated Valve Intelligent Diagnostic System (MOVIDS), which is used to obtain the accuracy of and to validate the applicability of the developed method in nuclear power plants. Finally, the accuracy of the developed method is presented and some examples applied to field data are discussed.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.160-167
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• 2018

This paper analyzed the effect of temperature on the permanent magnet flux and output torque. The major parameter which will impact the torque control accuracy of a surface mounted permanent magnet motor is the variation of the permanent magnet temperature. In addition, the temperature variation of the permanent magnet will also influence the maximum torque per ampere of the motor. To analyze the effect of temperature on the permanent magnet, the rotor of the motor was directly heated to measure the temperature and the permanent magnet flux was measured. As a result, the output torque of the motor decreases as the temperature of the rotor permanent magnet increases. Therefore, this paper proposes a technique to compensate the phase current of the motor by estimating permanent magnet flux, and it is proved through theoretical basis and several experiments.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.117-121
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• 2023

Research on walking assistance exoskeletons that provide optimized torque to individuals has been conducted steadily, and these studies aim to help users feel stable when walking and get help that suits their intentions. Because exoskeleton auxiliary efficiency evaluation is based on metabolic cost savings, experiments on real people are needed to evaluate continuously evolving control algorithms. However, experiments with real people always require risks and high costs. Therefore, in this study, we intend to actively utilize human musculoskeletal simulation. First, to improve the accuracy of musculoskeletal models, we propose a body segment mass distribution algorithm using body composition analysis data that reflects body characteristics. Secondly, the efficiency of most exoskeleton torque control algorithms is evaluated as the reduction rate of Metabolic Cost. In this study, we assume that the torque minimizing the Metabolic Cost is the optimal torque and propose a method for obtaining the torque.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.434-439
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• 2002

A diagnostic methodology, which utilizes only the remotely-measurable signals, has been requested to be developed in order to evaluate and monitor conditions of MOVs. It is proven that the stem thrust are the most important variables which provide the operability of MOVs. Therefore the stem thrust estimator was developed and validated, which estimates stem thrust by use of the motor torque. The motor torque is calculated using electrical signals which can be measured in Motor Control Center(MCC). The procedures to evaluate the accuracy of the diagnostic variables were set up and the accuracy of each variable was obtained through the experiments under various conditions. In addition, the applicability of the stem thrust estimator was tested in the plants.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.1-8
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• 2004

Applications of the deep hole drilling process can be found in many industries ranging from large aerospace manufacturer to small tool and die shop. Deep hole drilling process with small diameter generally requires high quality and accuracy. But problems which may arise or result from the deep hole drilling process include drill breakage, the generation of a finished part surface which does not satisfy required quality, and process instability. To guaranty the required machining quality and accuracy, it is important to understand and improve the deep hole drilling process. In this study, deep hole drilling experiments using tingle edge drill with small diameter under 2mm have been carried out for difficult to cut materials such as C42CrMo4 and C45pb and the experimental results were analyzed. Feed force and torque versus feed showed linear relationship in both materials. The feed force and torque are decreased as cutting speed is increased but the trends are not uniform in C42CrMo4.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.78-83
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• 1997

The paper presents the experimental analysis of a Stewart platform-based force-torque senor. The closed-form solution of forward kinematics of the Stewart platform is derived approximately by way of a linearization technique, and the solution is used in the force analysis of the force-torque sensor. An exper- mental studies show that the proposed method including gravity compensation algorithm is valid for Stew- art platform-based force-torque sensors. The performance of the developed force-torque sensor is evaluated in view of accuracy and linearity in measurements.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.63-70
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• 1994

This paper presents manufacturing and evaluation of a non-contact rotational torque measurement system which consists of torque cell, telemeter system, transmitter and receiver coil, transmitter, receiver and telemeter indicator. Static calibration test results show that the system has a maximum uncertaintry of 05% or less. A standar calibration system for rotational torque is used to evaluate the measurement system, As a result, the maximum uncertainty for measuring rotational torque by this system is 2% or less. We may conclude that the measurement system is sufficient to measure rotational torque of shaft in industry.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1097-1112
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• 1989

An iterative learning control scheme is incorporated to the computed torque method as a means to enhance the accuracy and the flexibility. A learning rule is constructed by utilizing a gradient descent algorithm and data compressing techniques are illustrated. Computer simulation results show a good performance of the scheme under a relatively high speed and a heavy payload condition.