• 국제물리치료학회지
• /
• 제4권2호
• /
• pp.566-572
• /
• 2013

This study aims to compared effect of balance between general walking exercise and power walking exercise. Twenty subjects were classified into two groups, general walking exercise(n=10) and power walking exercise(n=10). As a result, two group showed difference within the group and there is significant difference between two groups. 1) In compared static balance of sway area at pre-post test to exercise group, general walking exercise group did not change significantly. however, power walking exercise group did change significantly. and At sway distance, two group showed significant changes. 2) In compared Static balance between the groups sway area and sway path at pre-post test, two group showed significant changes. 3) In compared dynamic balance of center distance at pre-post test to exercise group, general walking exercise group was no significant difference in all directions. power walking exercise group was significant difference in all directions. 4) In compared dynamic balance between the groups sway area and sway path at pre-post test, there was no significant difference in leftward, rightward, forward directions and was significant difference in backward, overall direction. Therefore, power walking exercise can be recommended promote balance.

• 동력기계공학회지
• /
• 제2권1호
• /
• pp.73-79
• /
• 1998

In practical fields, the sway of crane systems leads to extra stress to the crane structure during the transporting operation and it is in close connection with its life. Usually, when we operate the cranes with high speed and manual control, the sway motion is irreducible. In this paper, a new type of crane system is proposed to avoid the irreducible sway of the crane systems. The proposed system is composed of mechanical arm with function of anti-sway based on conventional line system. By the anti-sway arm, we can realize to prevent the sway of the container box but cannot avoid the oscillation for the overall body of the crane. So, a controller design method to solve the above stated problem must be considered. The problem is solved by adopting the velocity pattern control methods of trapezoidal and curve types and its effectiveness is proved through experimental results.

• 동력기계공학회지
• /
• 제7권4호
• /
• pp.74-81
• /
• 2003

An LQ controller design method is proposed for effective anti-sway control of boom type crane in this paper. It is important for high productivity that the sway of a load is controlled as fast as possible when the trolley arrives to the destination with maximum velocity. To prove the effectiveness of the proposed LQ controller. simulations and experiments using the boom type crane as experimental device is carried out. Tracking performance for a step type reference and robustness for the change of working environment such as the change of load weight and parameters produced by a wire rope and disturbance by the wind arc proved by the experiment. It will be examined that boom type crane can be applied to industrial fields through experiment in this paper.

• 동력기계공학회지
• /
• 제7권3호
• /
• pp.54-60
• /
• 2003

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In this paper, we suggest a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In this paper, we apply the $H_{\infty}$ based control technique to the anti-sway control system design problem. And the experimental result shows that the proposed control system is shown to be useful and robust to disturbances like winds and initial sway motion.

• 동력기계공학회지
• /
• 제8권1호
• /
• pp.55-61
• /
• 2004

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In this paper, we suggest a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. In this paper, we apply the $H_{\infty}$ based control technique to the anti-sway control system design problem. And the experimental result shows that the proposed control system is useful and robust to disturbances like winds and initial sway motion.

• 동력기계공학회지
• /
• 제8권3호
• /
• pp.58-66
• /
• 2004

The sway motion control problem of a container hanging on the trolly is considered in the paper. In the container crane control problem, suppressing the residual swing motion of the container at the end of acceleration, deceleration or the case of that the unexpected disturbance input exists is main issue. For this problem, in general, many trolley motion control strategies are introduced and applied. In this paper, we introduce and synthesize a swing motion control system in which a small auxiliary mass is installed on the spreader made by ourselves. In this control system, the actuator reacting against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. Especially, we apply the $H_{\infty}$ based gain-scheduling control technique the anti-sway control system design problem of the controlled plant. In this control system, the controller dynamics are adjusted in real-time according to time-varying plant parameters. And the simulation result shows that the proposed control strategy is shown to be useful to the case of time-varying system and, robust to disturbances like winds and initial sway motion.

• 동력기계공학회지
• /
• 제2권1호
• /
• pp.67-72
• /
• 1998

In crane control system, it is required that the travelling time of crane must be reduced as much as possible and there is no the swing of load at the end and starting points. In this paper, we present a hybrid control method which includes two control methods of the optimal regulator and the velocity pattern control in order to realize high performance of the anti-sway. To implement the control algorithm, the dynamic equation is linearlized at an equilibrium point, so that the linear time invariant state equation can be obtained. A 1/10 sized model crane of the usual gantry cranes is made and used to show the applicability of the developed hybrid control method. The effectiveness of developed hybrid control method is proved by experimental results which show us good performance for anti-sway control comparing to conventional velocity pattern control. Practically, it is expected that the proposed control system will make an important contribution to the automatic crane control system of the industrial fields.

• 동력기계공학회지
• /
• 제7권1호
• /
• pp.51-59
• /
• 2003

The recent amount of container freight continuously has been increased, but the low efficiency of container crane causes jamming frequently in transportation and cargo handling at port. It is required that the working velocity and safety are improved by control of moving the trolley as quick as possible without large overshoot and any residual swing motion of container at the destination. In this paper, a LQ Fuzzy controller for a container crane is proposed to accomplish an optimal design of improved control system for minimizing the swing motion at destination. In this scheme a mathematical model for the system is obtained in state space form. Finally, the effectiveness of the proposed controller is verified through computer simulation.

• 동력기계공학회지
• /
• 제10권3호
• /
• pp.88-96
• /
• 2006

While the crane system operate in port, one of main objective is to transport containers to the goal position as soon as possible. Because this is one of the biggest problem in terms of productivity of port, the container crane is operated by an expert operator until now. However recently an automatic control system with high performance is required to improve the performance of the crane system and to make high productivity. Therefore we developed an optimal controller based on Humoral Immune Algorithm with PID controller. The proposed system has a real time structure and can improve the performance such as anti-sway problem. Some computer simulations are implemented to assess the characteristics of the proposed controller.

• Ocean Systems Engineering
• /
• 제9권3호
• /
• pp.219-240
• /
• 2019

This paper presents the comparison between SFT response with linear and nonlinear cables. The dynamic response analysis of submerged floating tunnel (SFT) is presented computationally with linear and nonlinear tension legs cables. The analysis is performed computationally for two wave directions one at 90 degrees (perpendicular) to tunnel and other at 45 degrees to the tunnel. The tension legs or cables are assumed as linear and non- linear and the analysis is also performed by assuming one tension leg or cable is failed. The Response Amplitude Operators (RAO's) are computed for first order waves, second order waves for both failure and non-failure case of cables. For first order waves- the SFT response is higher for sway and heave degree of freedom with nonlinear cables as compared with linear cables. For second order waves the SFT response in sway degree of freedom is bit higher response with linear cables as compared with nonlinear cables and the SFT in heave degree of freedom has higher response at low time periods with nonlinear cables as compared with linear cables. For irregular waves the power spectral densities (PSD's) has been computed for sway and heave degrees of freedom, at $45^0$ wave direction PSD's are higher with linear cables as compared with nonlinear cables and at $90^0$ wave direction the PSD's are higher with non-linear cables. The mooring force responses are also computed in y and z directions for linear and nonlinear cables.