The purpose of this paper is to demonstrate that vibrations of a truss structure can be suppressed nicely by a magneto-rheological (MR) fluid variable damper for semiactive vibration suppression. A variable MR fluid damper was designed and fabricated for this study. The principal characteristics of an MR damper were measured in dynamic tests, and a mathematical model of the damper was proposed. To investigate if the variable damper effectively suppresses the vibration of actual truss structures, semiactive vibration suppression experiments were performed using a cantilevered ten-bay truss beam. The experimental result has shown that the vibration was suppressed nicely by the variable MR damper, and that was compared with that of an electro-rheological (ER) damper investigated in previous research. The MR damper showed a higher performance than that of the ER damper.

Purpose: In this study, the effects of laughter therapy on levels of depression, quality of life, resilience and immune responses in breast cancer survivors were examined. Methods: A quasi-experimental nonequivalent control group, pretest-posttest design was used. Participants (n= 37) included breast cancer survivors who finished chemotheraphy and radiation therapy: 16 in the experiment group and 21 in the control group. Data were collected from August to November 2009. The experimental group participated in laughter therapy eight times, twice a week for 60 min per session. Questionnaires were used to measure pretest and posttest levels of depression, quality of life and resilience. A blood test was used to analyze changes in Total T cell, T helper, T suppressor, Th/Ts ratio, Total B cell, T cell/B cell ratio and NK cell for immune responses. Results: The results showed that laughter therapy was effective in increasing the quality of life and resilience in breast cancer survivors. but depression and immune responses did not differ significantly between the groups. Conclusion: The results of the study indicate that laughter therapy may be an effective nursing intervention to improve quality of life and resilience in breast cancer survivors.

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Ensuring the structural safety of a deployable solar panel under a severe launch vibration environment is one of the important factors for a successful CubeSat mission. A CubeSat’s deployable solar panel proposed in this study is effective to guarantee the structural safety of solar cells by attenuating launch loads owing to the superior damping characteristic achieved by a multilayered stiffener with viscoelastic acrylic tapes. The demonstration model of 3 U CubeSat’s deployable solar panel was fabricated and tested to validate the effectiveness of the proposed design. The basic dynamic characteristics of the solar panel were measured through free-vibration tests according to the various layers of the stiffener. Moreover, the characteristics of the deployed solar panel were measured and investigated under various temperatures to predict its capability under in-orbit operation. The effectiveness of the proposed design for launch vibration attenuation was demonstrated through qualification level sine and random vibration tests.

A low-power-consumption magneto-rheological (MR) fluid damper has been designed and fabricated to suppress the vibration of a space flexible structure. The MR damper fabricated in this study has advantages of both semi-active and optimal passive dampers, unlike the conventional MR and electro-rheological (ER) fluid semi-active damper. The vibration is thus damped quickly when the damper is controlled semi-actively, and the vibration energy is dissipated by an optimal passive damper in the absence of control. To implement the aforementioned damper, we fabricated an electromagnet combined with a permanent magnet. Its performance and the characteristics of the damper with the newly developed electromagnet were subsequently measured. The performance of the damper has been confirmed by vibration suppression experiments using 10-bay truss structures.

A stepper-actuated mechanism, such as a gimbal type antenna, is a major source of micro-jitters that affect the image quality of a high-resolution observation satellite. Attenuating micro-jitter disturbances induced by a stepper motor activation is one method of enhancing image quality of an observation satellite. In this study, we propose a novel gear with micro-jitter attenuation capability for stepper-actuated mechanism. This can be achieved by implementing a pseudoelastic shape memory alloy mesh washer on the gear wheel. This application makes it possible to achieve the gear with lower torsional stiffness and higher damping in the torsional direction of the gear, whose characteristics will assist in resolving the micro-jitter attenuation issues of a gear. The effectiveness of the gear proposed in this study was demonstrated by numerical simulation and jitter measurement tests using the gimbal type antenna mechanism actuated by the stepper motor.