• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.1-12
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• 2003

This study was performed to provide normative isokinetic strength of knee muscles of middle school non-athletic and athletic populations for rehabilitation and pre-season screening for injury prevention. Seven non-athletic subjects and 8 hockey players participated in this investigation. Each subject was tested at speeds of $60^{\circ}/sec$, $180^{\circ}/sec$, and $300^{\circ}/sec$. The free weight of lower leg was measured at speed of $60^{\circ}/sec$ to take gravity effect Into consideration when peak torque of knee muscles occurred. The results showed that the relative peak torque production of knee flexors did not change but the relative peak torque of knee extensors decreased significantly. Mamstring/quadriceps ratios increased mainly due to significant decreases in knee extensors torque production. No significant differences were found between groups. The hamstring/quadriceps ratios for both groups were significantly lower when the gravity effect was not eliminated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2706-2711
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• 1994

In this work, an experimental type of torque converter has been constructed and its characteristics have been evaluated by adapting an electrorheological fluid(ERF) as an operating medium. The device was designed by using the equations which were proposed by Carlson et al. The correlation between the rheological behaviour of an ERF and mechanical parameters of the clutch has been investigated. The torque generated by an ERF in this device is sum of one due to the yield strength by polarizing dispersed particles in dielectric oil and one due to the viscous drag. The experimental results are presented in terms of torque and current density as a function of rotational speed at various electric field strength applied. Experimental results showed that the measured torque was rapidly increased with the increase of the electric field, generally being proportional to the rotational speed of the motor. The measured current was shown to be increased with the increased electric field. Also, the current was decreased with the increase of increased with the increased electric field. Also, the current was decreased with the increase of the rotational speed of the motor and reached plateau region after f = 5 Hz.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1320-1329
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• 1990

A static performance tester for a torque rod assembly was developed to evaluate the three characteristics of the rod rubber bushing : radial spring characteristic, thrust spring characteristic, and rotational torque characteristic. Among the various schemes considered in the conceptual design stage, the final versatile type was determined to perform three different tests in one machine. The performance testing machine carried out radial spring test, thrust spring test, and torque test of the torque rod assembly. Static performance of the torque rod assembly was evaluated with the tester developed and fatigue strength of the assembly was also tested with the servo-hydraulic structural fatigue testing machine. The life of the component was found to be related with the rubber quality and adhesionability between the rubber and the steel rod. The optimum rubber hardness was experimentally found by changing the chemical compositions of rubber, and the adhesion was improved by optimizing the shape of the outer section of a the rubber, this study ensured the development of a reliable torque rod assembly.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.310-315
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• 2015

Purpose: The purpose of this study was to measure the tightening torque for dental implant in dental laboratory and to analyze of the effects of different tightening torque. Materials and Methods: The tightening torque for dental implant in dental laboratory were measured by digital torque gauge. The length of abutment and analog were measured as tightening torque of manufacturer's instructions and the measured value. And the data were statically analyzed. Results: The mean tightening torque of implant screw in dental laboratory was $1.563{\pm}0.332Ncm$. The external type implant system of total length were showing no significant differences but the internal type implant system had difference significant (P < 0.05) when compared with tightening torque. Conclusion: The implant prosthesis should be made under manufacturer's instructions especially as tightening torque of screw. For the fidelity of implant prosthesis, dental technician should learn how to use the torque gauge.

• Journal of Periodontal and Implant Science
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• v.43 no.1
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• pp.30-36
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• 2013

Purpose: Implant stability at the time of surgery is crucial for the long-term success of dental implants. Primary stability is considered of paramount importance to achieve osseointegration. The purpose of the present study was to investigate the correlation between the insertion torque and primary stability of dental implants using artificial bone blocks with different bone densities and compositions to mimic different circumstances that are encountered in routine daily clinical settings. Methods: In order to validate the objectives, various sized holes were made in bone blocks with different bone densities (#10, #20, #30, #40, and #50) using a surgical drill and insertion torque together with implant stability quotient (ISQ) values that were measured using the Osstell Mentor. The experimental groups under evaluation were subdivided into 5 subgroups according to the circumstances. Results: In group 1, the mean insertion torque and ISQ values increased as the density of the bone blocks increased. For group 2, the mean insertion torque values decreased as the final drill size expanded, but this was not the case for the ISQ values. The mean insertion torque values in group 3 increased with the thickness of the cortical bone, and the same was true for the ISQ values. For group 4, the mean insertion torque values increased as the cancellous bone density increased, but the correlation with the ISQ values was weak. Finally, in group 5, the mean insertion torque decreased as the final drill size increased, but the correlation with the ISQ value was weak. Conclusions: Within the limitations of the study, it was concluded that primary stability does not simply depend on the insertion torque, but also on the bone quality.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.85-91
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• 2007

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any auto lift and auto dropping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1454-1457
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• 2003

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any AUTO LIFT and AUTO Drooping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.208-210
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• 1994

In this paper, the design sensitivity evaluation based on the 2-dimensional finite clement discretization is presented for the voltage source and eddy current problem. And it is applied to the two shape design problems of the rotor slot of 3-phase squirrel cage induction motors. The first is to increase the starting torque while keeping the rated torque fixed. The other is only to increase the torque at the rated speed while keeping the starting torque fixed. As an optimization method, the Gradient Projection method is used to control casily the torques for various speeds of rotor. One fourth of rotor is analyzed by using a semi-periodic boundary condition. Because the shape of rotor slot has much influence on the slip torque characteristic, the 10 design parameters are taken on the interface between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal typo with rounding corners.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.1
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• pp.24-33
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• 2010

Design of a Pump Jet Propulsor (PJP) was undertaken for an underwater body with axisymmetric configuration using axial/low compressor design techniques supported by Computational Fluid Dynamics (CFD) analysis for performance prediction. Experimental evaluation of the PJP was earned out through experiments in a Wind Tunnel Facility (WTF) using momentum defect principle for propulsive performance prior to proceeding with extensive experimental evaluation in towing tank and cavitation tunnel. Experiments were particularly conducted with respect to Self Propulsion Point (SPP), residual torque and thrust characteristics over a range of vehicle advance ratio in order to ascertain whether sufficient thrust is developed at the design condition with least possible imbalance torque left out due to residual swirl in the slip stream. Pumpjet and body models were developed for the propulsion tests using Aluminum alloy forged material. Tests were conducted from 0 m/s to 30 m/s at four rotational speeds of the PJP. SPP was determined confirming the thrust development capability of PJP. Estimation of residual torque was carried out at SPP corresponding to speeds of 15, 20 and 25 m/s to examine the effectiveness of the stator. Estimation of thrust and residual torque was also carried out at wind speeds 0 and 6 m/s for PJP RPMs corresponding to self propulsion tests to study the propulsion characteristics during the launch of the vehicle m water where advance ratios are close to Zero. These results are essential to assess the thrust performance at very low advance ratios to accelerate the body and to control the body during initial stages. This technique has turned out to be very useful and economical method for quick assessment of overall performance of the propulsor and generation of exhaustive fluid dynamic data to validate CFD techniques employed.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.898-899
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• 2015

This paper present a transient experiment to verify the performance of limited angle torque motor(LATM) designed using electromagnetic transient analysis. LATM requires access to the transitional state to the torque performance evaluation. Because LATM moves the rotor using a magnetic torque generated by the interaction of the permanent magnet and the armature winding. A separate control is not applied, it is switched on at the same time under the conditions that the current applied to the armature winding. It was compared to the transient analysis of the experimental data of LATM for the verification of approach method in the transitional state.