• Journal of Korean Physical Therapy Science
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• v.3 no.2
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• pp.951-961
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• 1996

Isokinetic exercise is dynamic, but the spped of movement must be regulated so that the resistance is in ratio to the force applied at each point throughout the full range of motion. The purpose of this study is to comparise with trunk flexors & extensors of isokinetic evaluation of pre-exercise and post-exercise in operated laminectomy & disectomy patients. 7 subjects were examined at $120^{\circ}$/sec and $60^{\circ}$/sec each 15 days. The results were as follows; 1. Peak torque of extensors on $60^{\circ}$/sec showed significant difference statistically(p<0.05), but peak torque of flexors on $60^{\circ}$/sec showed no significant difference statistically. 2. Trunk flexors/extensors ratio of peak torque of $60^{\circ}$/sec showed no significant difference ststistically. 3. Peak torque % B.W of extensors on $60^{\circ}$/sec showed significant difference statistically(p<0.05), but peak torque % B.W of flexors on $60^{\circ}$/sec showed no significant difference statistically. 4. TAE of extensors on $60^{\circ}$/sec showed significant difference statistically (p<0.05), but TAE of flexors on $60^{\circ}$/sec showed no significant difference. 5. Total work of flexors & extensors on $60^{\circ}$/sec showed significant difference statistically (p<0.05). 6. Average power of flexors & extensors on $120^{\circ}$/sec showed significant difference statistically(p<0.05). 7. Endurance ratio of flexors & extensors on $120^{\circ}$/sec showed no significant difference statistically. 8. Set total work of flexors & extensors on $120^{\circ}$/sec showed significant difference statistically(p<0.05). 9. TAE of extensors on $120^{\circ}$/sec showed significant difference statistically(p<0.05), TAE of flexors on $120^{\circ}$/sec showed no significant difference statistically. 10. Total work of flexors & extensors on $120^{\circ}$/sec showed significant difference statistically (p<0.05).

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.525-533
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• 1998

A conventional contact type brake system which uses a hydraulic system has mny Problems such as time delay response due to pressure build-up, brake pad wear due to contact movement, bulky size, and low braking performance in high speed region. As vehicle speed increases, a more powerful brake system is required to ensure vehicle safety and reliability. In this work, a contactless brake system of an eddy current type is proposed to overcome problems. Optimal torque control which minimizes a braking distance is investigated with a scaled-down model of an eddy current type brake. It is possible to realize optimal torque control when a maximum friction coefficient (or desired slip ratio) corresponding to road condition is maintained. Braking force analysis for a scaled-down model is done theoretically and experimentally compensated. To accomplish optimal torque control of an eddy current type brake system, a sliding mode control technique which is, one of the robust nonlinear control technique is developed. Robustness of the sliding mode controller is verified by investigating the braking performance when friction coefficient is varied. Simulation and experimental results will be presented to show that it has superior performance compared to the conventional method.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.404-407
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• 2003

In this paper, we have designed the humanoid robot's leg parts with 12 D.O.F. This robot uses ankle's joints to confirm stability of walking performance. It is less movable to use ankle's joints than to do upper body's balancing joints like IWR-III, which needs three parts of via points, support leg, swing leg and balancing joints. Instead, the proposed humanoid robot needs support leg and swing leg via points. ZMP(Zero Moment Point) is utilized to guarantee the stability of robot's walking. The humanoid robot uses the ankle's joints to compensate for IWR-III's balancing joints movement. Actually we concern about a motor performance when making a real humanoid robot. So a simulator is employed to know each joint torque of humanoid robot. This simulator needs D-H(Denavit-Hartenberg) parameters, robot's mass property and two parts of via points. The simulation results are robot's walking trajectories and each motor torque. Using the walking trajectories, we can see the robot's walking scene with 3D simulator. Before we develop the humanoid robot, simulation of the humanoid robot's walking performance is very helpful. And the torque data will be used to make humanoid's joint module.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.212-216
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• 2016

Purpose: The current study seeks to identify the relationship between torque values of the quadriceps and muscle activity during isometric and isokinetic exercises. Methods: The subjects of the study included 29 healthy individuals 17 men and 12 women) who took part in isometric and isokinetic exercises that utilized the quadriceps. The isometric exercises were performed three times each at 4 different angles (0, 30, 60, and 90 degrees). For the isokinetic exercises, concentric contraction and eccentric contraction were undertaken three times each at two angular velocities (30 and 60 degrees). Results: The muscle activity of the quadriceps during the isometric exercises showed significant differences at the 30, 60, and 90 degree angles. During the concentric contractions and eccentric contractions, muscle activity at the peak torque of the quadriceps indicated significant differences in vastus medialis, vastus lateralis, and rectus femoris at angular velocities of 30 and 60 degrees. Conclusion: When applied clinically based on the biomechanical analysis of the current study, it is possible to anticipate and selectively strengthen muscles with isometric and isokinetic exercises for not only healthy adults and professional athletes, but also for those who experience limited knee movement for long periods following knee surgeries.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1213-1218
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• 2007

The brake judder comes from non-uniformities in the tire/wheel assembly caused by mechanical effects such as a brake torque variation (BTV). A disc thickness variation (DTV) related with the kinematic behavior of the disc was investigated a main source of BTV. In this study, a dynamic model with brake corner assembly of full vehicle using MSC.ADAMS was correlated by experiment of judder phenomenon. Judder was generated and correlated systematically by judder experiment in chassis and brake dynamometer from variation in the thickness of the disc. Also it has been found a judder transfer path and variation of the braking pressure. Through analysis of transfer function and movement of subsystem caused by BTV generation, design parameters have been found. Based on the results obtained from parameter study of suspension module, the effective design process and developed model with brake corner assembly was suggested for vibration reduction of steering wheel caused by the judder phenomenon.

• Tribology and Lubricants
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• v.29 no.1
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• pp.1-6
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• 2013

Hydraulic transmission is the main component delivering power to the drive wheels of an excavator during forward and backward movement, and it has low speed, high torque and high speed, low torque gear change ratios as a forward/backward two-speed main function. It also has additional function of ensuring that the excavator is stably fixed on the ground with the built-in parking brake during excavation operations. In this study, optimal design specifications are determined by modeling and simulating about the multi-disc-type friction clutch, which is the main component improving the reliability of the hydraulic transmission for a 14-ton wheel excavator, and the friction properties of the transmission clutch are analyzed by performing sample tests.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.40-46
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• 2003

Synchronizing errors between the spindle motor and the z-axis motor directly influences the cutting characteristics and the thread quality in tapping, because the tapping process is accomplished by synchronizing the movement of the z-axis with the revolutionary spindle motion. Generally synchronizing errors are decided by tile parameters of the servo system and commanded velocity. The excessive synchronizing errors which are induced by the parameter mismatch and high cutting velocity can cause tap breakage due to the abrupt increase of cutting torque or damage the thread accuracy by overcutting the already cut threads. In this paper, the influences of the synchronizing errors on the tapping characteristics in the ultra high-speed tapping will be described and a minimum level of synchronizing errors necessary to maintain the quality of the cut thread will be presented.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.1
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• pp.28-34
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• 2012

Human generally uses three methods to keep balance. One of them is using reactive momentum such as swing an upper body or arms. In this study, we proposed a balancing controller for the reactive momentum method using an inverted pendulum. We simplified a human or a humanoid robot as a two-link inverted pendulum having two edges. In addition, we proposed a distinctive condition for controller transition. If a human is pushed, he has to change a balancing controller from using an ankle torque to using a reactive momentum or changing foot placement. When the balancing controller is changed from using an ankle torque to using a reactive momentum, it is required a proper timing to keep a stability and make smooth movement. In the experiment, the proposed controller and distinctive condition were verified.

• Journal of Biosystems Engineering
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• v.19 no.3
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• pp.175-184
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• 1994

This study was conducted to investigate experimentally the basic characteristics of the torque of the cutterbar driving shaft as the double-knife was used instead of the conventional standard single-knife type. A new design for inclined setting of the cutterbar relative to the direction perpendicular to combine harvester movement was investigated to test a possible reduction of concentrated load caused by the simultaneous cutting of many rows. It was evaluated that the maximum torque and mean total power of the driving shaft due to the cutting resistance of the rice straw were largely depended upon the rotational shaft-speed and straw feeding rate, but were resepectively 1.1~2.3 and 1.15~1.34 times higher compared to those while idling. It was also proved that the inclined setting of the cutterbar could save a considerable amount of energy required for its driving shaft.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.335-346
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• 2001

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016'X.022', .017'X.022', .017'X.025', .018'X.025', .019'X.025', .020'X.025', .021'X.025'. In 018' bracket, 016'X.022', .017'X.022', .017'X.025' wires were inserted and in 022' bracket, all the sizes of wires except .016'X.022' were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021'X.025' wire was about 1.75 times as large as that on the .016'X.022' wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.