• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.599-607
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• 2011

In this paper, a reaction-force compensation system for an XY linear motion stage, without an additional external isolation structure or extra motors, is developed. This system consists of a movable magnet track, a spring, a dummy weight, and a dedicated sensor module that measures the relative positions of the movable magnet track with respect to the motor coil. The reaction force compensation system is modeled, and simulations are carried out to optimize design parameters such as the moving distance of the magnet track, the transmission force, the dummy weight, and the allowed size of the mechanism. An XY linear motion stage is built, incorporating the reaction force compensation system, and the performance of the system is verified experimentally. For acceleration and deceleration values of 10 m/$s^2$, 85% of the reaction force is absorbed by the reaction force compensation system.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.10-13
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• 2021

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm³. The polystyrene sphere levitated at the current density of 0.83 A/cm² and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.1-10
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• 2017

For dismantling heavy structure under special environment in radioactivity, there are many problems which should be tele-operated and feedback a cutting force for cutting a thick structure such as concrete. When operator dismantles a thick heavy concrete structure, it is in sufficient to judge whether robot is contacting or not with environment by using only vision information. To overcome this problem, force feedback and impedance model based bilateral control are introduced. The sliding mode control with sliding perturbation observer (SMCSPO) based bilateral control is applied and surveyed to a single rod hydraulic cylinder in this paper. The sliding mode control is used for robustness against a disturbance. The sliding perturbation observer is used for estimation of a reaction force such as cutting force. The bilateral control is executed using the information of reaction force estimated by SMCSPO. The contribution of this paper is that the estimation method and bilateral control of the single rod hydraulic cylinder are introduced and discussed by experiment.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.1
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• pp.222-228
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• 2011

With comparison of maximum vertical reaction force and lower limb on drop landing between normal and flat foot group, this study is to provide fundamental data of the prevention of injury and the treatment of exercise which are frequently occurred on flat foot group's drop landing. The surface electrodes were sticked on lateral gastrocnemius muscle, medial gastrocnemius muscle, tibialis anterior and the drop landing on a force plate of 40cm was performed with a normal group who had no musculoskeletal disease and a flat foot group of 9 people who had feet examinations. Vertical reaction force were significantly statistically different between two groups(p<.001). Muscle activity of lower limbs in all three parts were not statistically different but showed high tendency on average in the flat foot group. The flat foot group had difficulties in diversification of impact burden and high muscle activity. Therefore, it was suggested that muscular strengthening of knee joints and plantar flexions of foot joints which were highly affected in impact absorption will be required.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.165-172
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• 2001

Wheel bearing units were almost exclusively used for car front wheel, where the two ball rows are directly side by side with integrated rubber seal. The seal is of important for wheel bearing units due to the adverse environmental conditions with mud and splash water. The seal of wheel bearing units was designed to have geometry with multi lips, which elastic lip contacts and deforms with bearing. The equation of reaction force for deformed lip as cantilever beam was previously used for seal lip design. But it's result was not useful because deflection of the beam differs from lip's. In this study, deformed shape of the lip was assumed to and order function which is more similar to lip deformation and made the equation for reaction force prediction. The Reaction forces from each other equations were compared with results by FEA to prove usefulness of new equation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.79-86
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• 2001

A method for actively minimizing dynamic reaction forces in a flexible structure subject to persistent excitations is presented. One difficulty with the method, however, is that forces and moments do not converge as quickly as displacements in mathematical discretization of continuous systems, so a controller based on a truncated model of a continuous system can produce poor results. A technique using residual flexibility matrix is presented for correcting the truncated force representation. A controller designed for reaction force minimization, using the residual flexibility matrix, is applied to a model of a flexible structure, and the results are presented. Implications of various reaction force penalty combinations on the resulting control performance are also discussed.

• Journal of Ocean Engineering and Technology
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• v.19 no.3
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• pp.11-17
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• 2005

The effect of frequency and amplitude of the OWC (Oscillating Water Column) motion on the nonlinear reaction forces in an air duct are studied experimentally. Experimental owe model is idealized as a simple circular cylinder with an orifice type air duct located at the middle oj the top rid. Reaction forces due to forced heave oscillation are measured and analyzed. By subtracting the effect of inertia forces and restoring forces, pneumatic damping force and added spring force are deduced. The effects of the frequency and amplitude of the heave motion are discussed. Also, the effects of solidity of the duct on the reaction forces are discussed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.212-219
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• 2004

The effect of frequency and amplitude of the OWC (Oscillating Water Column) motion on the nonlinear reaction forces in an air duct arc studied experimentally. Experimental OWC model is idealized as a simple circular cylinder with an orifice type air duct located at the middle of the top rid. Reaction forces due to forced heave oscillation are measured and analyzed. By subtracting the effect of inertia forces and restoring forces, pneumatic damping force and added spring force are deduced. The effects of the frequency and amplitude of the heave motion are discussed. Also, the effects of solidity of the duct on the reaction forces are discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1160-1165
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• 2004

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces of the ankle joint during the waist pulling, and to assess the ankle joint reaction forces according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 cameras, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and joint reaction forces during the recovery of postural balance control. From the experiment using falling mass perturbation, joint moments were larger than those from the experiment using air cylinder pulling system with milder perturbation. However, JRF were similar nevertheless the difference in joint moment. From this finding, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movement of flexion or extension or compensating joint reaction force with surrounding soft tissues. Therefore, biomechanical analysis of human ankle joint presented in this study is considered useful for understanding balance control and ankle injury mechanism.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1864-1873
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• 1993

A biomechanical approach was carried out to analyze foot-floor reaction forces acting on five male subjects performing a walking task. The task analyzed was walking over an obstacle with the right bare foot. The foot-floor reaction data were measured from a force plate, and then processed using a software developed. The source program was coded in the C language for easier on-line data acquisition and graphic displays. High repeatability was found in the reaction data acquired from three trials by each subject. For obstacle height from 0 to 25 cm, the maximum in reaction force reached up to 1.048 BW in the vertical, 0.174 BW in the anterior-posterior, and 0.054 BW in the medio-lateral components, respectively. A quantity was defined by the difference between two vertical reaction values, and this quantity was found to be proportional to the obstacle height. It was also shown that the whole body motion could be predicted the measured foot-floor reaction data.