• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.75-80
• /
• 2007

This paper is concerned with the dynamic modeling and controller design for a cylindrical shell equipped with MFC actuators. The dynamic model was derived by using Rayleigh-Ritz method based on Donnel-Mushtari shell theory. The actuator and sensors for the MFC actuator equations were derived based on pinforce model. The boundary conditions at both ends were assumed to be shear diaphragm. After calculating the natural vibration characteristics, the positive position feedback controller was designed to cope with the first two modes. To this end, the equations of motion were reduced to modal equations of motion by considering the modes of interest. The theoretical results show that vibrations can be successfully suppressed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.103.3-103
• /
• 2001

Recently Electro active polymer has been discussed in various researches as new actuators replacing the human muscles. Since they have confronted a limitation of more advanced application with traditional actuator. IPMC (Ion exchange Polymer Metal Composite) is one of candidate materials for new actuators. In this paper, we propose a new approach and design principle for the IPMC polymer actuator to conquer the weaknesses of IPMC that is intrinsic weak structural stiffness and low trust forces. In the first we performs some experimental works about how the basic specific characteristics of IPMC vary and what the optimal operating conditions are. And we have applied IPMC as active cilium for realization of annelida motion like ...

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.7
• /
• pp.36-42
• /
• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.

• Wind and Structures
• /
• v.2 no.3
• /
• pp.201-251
• /
• 1999

Flexible structures may experience excessive levels of vibration under the action of wind, adversely affecting serviceability and occupant comfort. To ensure the functional performance of a structure, various design modifications are possible, ranging from alternative structural systems to the utilization of passive and active control devices. This paper presents an overview of state-of-the-art measures that reduce the structural response of buildings, including a summary of recent work in aerodynamic tailoring and a discussion of auxiliary damping devices for mitigating the wind-induced motion of structures. In addition, some discussion of the application of such devices to improve structural resistance to seismic events is also presented, concluding with detailed examples of the application of auxiliary damping devices in Australia, Canada, China, Japan, and the United States.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.1
• /
• pp.92-106
• /
• 1990

Active compliance is often used in the control of robot manipulators for the implementation of complex tasks such as assembly, multi-finger fine motion, legged-vehicle adaptive control,etc. This technique balances the interactive force between the manipulator tip and its working environment with its position and velocity errors to achieve the operation of a damped spring. This paper investigates the effecft of passive compliance on system stability with regard to force feedback implementation for actively compliant motion. Usually it is understood that accurate position control require a stiff system. However, theoretical examination of control experiments on a legged suspension vehicle suggests that, if the control includes discrete-time force feedback, some passive compliance is necessssary at the legs of the vehicle for system stability. This can be an important factor to bl considered in manipulator design and control. A theoretical analysis, numerical simulation, and experimental result, confirming the above conclusion, are introduced in this paper.

• Structural Engineering and Mechanics
• /
• v.51 no.5
• /
• pp.743-754
• /
• 2014

Investigations of regular and chaotic vibrations of the autoparametric pendulum absorber suspended on a nonlinear coil spring and a magnetorheological damper are presented in the paper. Application of a semi-active damper allows controlling the dangerous motion without stooping of system and additionally gives new possibilities for designers. The investigations are curried out close to the main parametric resonance. Obtained numerical and experimental results show that the semi-active suspension may reduce dangerous motion and it also allows to maintain the pendulum at a given attractor or to jump to another one. Moreover, the results show that, for some parameters, MR damping may transit to chaotic motions.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.317-319
• /
• 1996

Utilizing a Calcium filter, a large two ribbon flare of an importance 2.5Xj31? was recorded at. King Abdul-Aziz University Solar Observatory (KAAUSO) at the 30th of October 1991. This chromosphenc flare observation, which is of special importance since it is rarely reported, was for a flare that occurred near the south west of the equator at the vicinity of a large sunspot group on an active region known as AR 6891. The observed foot points of this flare had a strange behavior in which the separating motion of the ribbons were not typical of most flares, rather were nearly orthogonal. In this article we present the characteristics of the main sunspot group of this active region and try to investigate its evolution and fragmentation with time. Information regarding magnetic fields and velocity fields are necessary to understand the restructuring of the magnetic field pattern and plasma motion, and hence the changes that could lead to the occurrence of such an interesting flare.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.3 s.303
• /
• pp.15-22
• /
• 2005

This paper proposed a object tracking algorithm which can track contour of fast moving object through motion estimation. Since the proposed tracking algorithm is based on the radial representation, the motion estimation of object can be accomplished at the center of object with the low computation complexity. The motion estimation of object makes it possible to track object which move fast more than distance from center point to contour point for each frame. In addition, by introducing both gradient image and difference image into energy functions in the process of energy convergence, object tracking is more robust to the complex background. The results of experiment show that the proposed algorithm can track fast moving object in real-time and is robust under the complex background.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.44 no.5
• /
• pp.64-72
• /
• 2007

In this paper we proposed a combined active contour model and motion estimation-based object tracking technique. After assigning the initial contour, we find the object's boundary and update the initial contour by using object's motion information. In the following frames, similar snake algorithm is repeated to make continuously estimated object's region. The snake algerian plays a role in separating the object from background, while motion estimation provides object's moving direction and displacement. The proposed algorithm provides equivalently stable, robust, tracking performance with significantly reduced amount of computation, compared with the existing shape model-based algorithms.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.30 no.2
• /
• pp.1-12
• /
• 2024

Background: This study aimed to determine the effects of pectoralis minor stretching, lower trapezius strengthening exercise with serratus anterior strengthening exercise to find an effective therapeutic exercise for alignment, shoulder range of motion, muscle imbalance of rounded shoulder patient. Methods: This study targeted on a total of 28 male subjects, aged 20s and 30s, and randomly divided the subjects into each group, with 14 subjects each. The experimental group performed pectoralis minor stretching, lower trapezius strengthening exercise, and serratus anterior strengthening exercise, while the control group performed pectoralis minor stretching and lower trapezius strengthening exercise. Results: both group showed an increase in active range of motion for shoulder flexion, a muscle activity of the serratus anterior muscle and the lower trapezius muscle, a decrease in muscle activity of the upper trapezius muscle, and a significant improvement in scapular alignment after the intervention. In the comparison between group, the experimental group showed greater increased shoulder joint flexion range of motion, serratus anterior muscle activity, and decreased upper trapezius muscle activity than the control group. Conclusion: Performing serratus anterior strengthening exercises with pectoralis minor stretching and lower trapezius strengthening exercises is effective for improving the active range of motion in shoulder joint flexion and muscle imbalance