• Geotechnical Engineering
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• v.3 no.4
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• pp.31-40
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• 1987

A helical probe test (HPT) suitable for in.situ soil exploration to a shallow depth and compaction control were developed and tested in different soils alongside traditional in-situ tests, including Standard Penetration Test (SPT), Cone Penetration Test (CPT) and in-situ density test. The helical probe test is economical and can be performed by a single person. The torque necessary to insert the probe Is used as a measure of soil characteristics. It was found that: the HPT test correlates well with the SPT test and the correlation is not sensitive to the soil type; the HPT test correlates well with the CPT test, but the correlation is sensitive to the soil type; the HPT torque provides a sensitive measure of relative compaction rind in-situ dry density of compacted soils; the reverse torque ratio decreases with increasing average grain sloe.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.1
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• pp.11-24
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• 2017

The present work focuses multi-objective optimization of blade sweep for a Wells turbine. The blade-sweep parameters at the mid and the tip sections are selected as design variables. The peak-torque coefficient and the corresponding efficiency are the objective functions, which are maximized. The numerical analysis has been carried out by solving 3D RANS equations based on k-w SST turbulence model. Nine design points are selected within a design space and the simulations are run. Based on the computational results, surrogate-based weighted average models are constructed and the population based multi-objective evolutionary algorithm gave Pareto optimal solutions. The peak-torque coefficient and the corresponding efficiency are enhanced, and the results are analysed using CFD simulations. Two extreme designs in the Pareto solutions show that the peak-torque-coefficient is increased by 28.28% and the corresponding efficiency is decreased by 13.5%. A detailed flow analysis shows the separation phenomena change the turbine performance.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.318-325
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• 2019

NREX, an upper limb exoskeleton robot, was developed at the National Rehabilitation Center to assist in the upper limb movements of subjects with weak muscular strength and control ability of the upper limbs, such as those with hemiplegia. For the free movement of the shoulder of the existing NREX, three passive joints were added, which improved its wearability. For the flexion/extension movement and internal/external rotation movement of the shoulder of the robot, the ball lock pin is used to fix or rotate the passive joint. The force and torque between a human and a robot were measured and analyzed in a reaching movement for four targets using a six-axis force/torque sensor for 20 able-bodied subjects. The addition of two passive joints to allow the user to rotate the shoulder can confirm that the average force of the upper limb must be 31.6% less and the torque must be 48.9% less to perform the movement related to the axis of rotation.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.12 no.2
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• pp.21-25
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• 2006

Objective: The purposes of this study are to provide fundamental data and a rehabilitation program in physical therapy. It has been operated by 30 male college students for lumbar isokinetic exercises. Method : Subjects have been carried out in an experiment by Biodex system operating isokinetic torso rotation. This performance was activated by left rotation after right rotation repeatedly. Results: 1. The mean peak torques at $60^{\circ}$/sec were $95.6{\pm}20.62$ (Rt) and $93.84{\pm}18.41$ (Lt). 2. The mean peak torques/body weight at $60^{\circ}$/sec were $69.28{\pm}28.31$ (Rt) and $67.07{\pm}27.04$ (Lt). 3. The total works in right side at $60^{\circ}$/sec and $180^{\circ}$/sec were $492.21{\pm}92.37$, $1294.97{\pm}278.96$ and in left side at $60^{\circ}$/sec and $180^{\circ}$/sec were $515.78{\pm}109.47$, $1443.74{\pm}329.67$. 4. The work to body weight ratio at $60^{\circ}$/sec was $78.30{\pm}32.37$ (Rt) and $79.93{\pm}37.30$ (Lt). 5. The average powers in right side at $60^{\circ}$/sec and $180^{\circ}$/sec were $76.75{\pm}16.69$, $117.19{\pm}29.94$ and in left side at $60^{\circ}$/sec and $180^{\circ}$/sec were $78.54{\pm}18.58$, $125.39{\pm}32.90$. 6. The work fatigue at $180^{\circ}$/sec was $21.76{\pm}14.82$ (Rt) and $19.66{\pm}26.23$ (Lt). Conclusion: In right side and left side, there was no significant difference in peak torque. peak torque/body weight, work to body-weight ratio, average power of trunk rotators at $60^{\circ}$/sec(p<0.05). However there was a significant difference in the total work of trunk rotators at $60^{\circ}$/sec(p>0.05). Also there was a significant difference in the average of trunk rotators at $180^{\circ}$/sec(p>0.05).

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.595-597
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• 2002

This paper presents an optimum design, which is able to determine optimal geometric and electric parameters of Switched Reluctance Motor so as to fit respective operating conditions specified in various industrial fields. Those works describe an approach to maximize the average torque while keeping the torque ripple within 10${\sim}$100(%) of respective limited values. This optimum design is obtained by uniting an optimization algorithm of PQRSM to a time stepping finite element method.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.113-115
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• 2003

This paper presents the optimal design of a brushless DC motor(BLDC) keeping the average torque and cogging torque of the initial model while minimizing the volume of magnet pole by FEM and evolution strategy. Experimental tests are performed by the finite element method(FEM), and the random based evolution strategy is applied for the shape optimization. The optimal result shows a largely reduced volume of magnet pole.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.190-192
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• 2003

Single phase induction motor is used widely in various electronic appliances by advantage that is simple structure and a low-cost. As high starting torque characteristic is mostly used capacitor run single phase induction motor. In this paper, it is applied that speed controller of Capacitor run single phase induction motor of digital way used general microprocessor, and phase control method used average voltage. Torque get non-linearity to domain of low speed. Unstable domain of low speed is applied of integral cycle control. so it is wide that Speed control domain. Also, PID controller is used to improve characteristic of fast response. The validity of proposed method is verified from simulation and experiment result

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.150-152
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• 2007

The stator faults yield asymmetrical operation of induction machines, such as irregular current, torque pulsation, increased losses and decreased average torque. So it is necessary to detect the stator faults and develope the monitoring system for detecting faults including vibration and noise. This paper describes the method to analysis the induction motors with the stator winding inter-turn short for investigation of the asymmetrical operation during normal and transient states. And a simple method is used for the simulation and analysis of the induction machines with stator asymmetries. Finally, simulation results, finite element analysis and experimental ones are presented. The results can be useful for real-time on-line monitoring of an induction motor.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.163-165
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• 1993

This study describes the influence of the mutual inductance between the adjacent phase windings of variable reluctance motor[VRM] and presents a new type of inverter for reduction of such influence. In this inverter topology, though an additional power switch is used as compared with the conventional C-dump inverter circuit, unwanted negative torque produced by the mutual inductance is remarkably reduced. Hence, the circuits results in increase of the average torque and contributes to the improvement of overall drive efficiency. Theoretical prediction is verified by experimental results obtained with the integration of presented inverter and prototype 6/4 VRM.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.43-45
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• 2004

This paper presents the optimal design of a brushless DC motor(BLDC) keeping the average torque and cogging torque of the initial model while minimizing the volume of magnet pole. Experimental design method and evolution strategy technique are performed for the shape optimization. The presented optimal designs show the both methods have the almost same result.