Quick picking and heavy lifting are the most common problems in current workplaces. They can cause lumbar muscle damage. The operator then must spend energy, time, and money for recovery or rehabilitation. To solve this problem, we developed a passive-type assistive suit using air mesh material, elastic band, and wire. To determine the strength support effect of the passive-type assistive suit, electromyography (EMG) was performed for eight muscles and the maximum voluntary contraction (MVC) was analyzed when lifting weights of 0%, 15%, and 30% of the subject’s weight in a Semisquat motion. Results showed that MVC increased as the weight of the heavy object increased. However, its increase was not proportional to the decrease in MVC according to the presence or absence of assistive suits or the weight of the heavy object. The highest MVC was observed for the erector spinae muscle under all conditions. The greatest decrease in MVC according to working clothes was measured for the vastus lateralis muscle (lifting: 17.7±2.95%, lowering: 18.3±0.55%). These results show that lifting work performed while wearing a passive-type assistive suit using wires and elastic bands is effective in assisting muscle activity.
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If fatigue failure occurs during aircraft operation, it can cause catastrophic injuries. So, it is necessary to study fatigue failure at the design stage. Frequency domain fatigue analysis is used to predict fatigue failure. During frequency domain fatigue analysis, results can be calibrated by PSD analysis. In this study, fatigue failure is predicted by the Dirlik method, Lalanne method and Steinberg method. Regarding results, life determined by the Dirlik method, Lalanne method and Steinberg method were 8.737, 8.314, and 7.901 times the standard life, respectively. The Steinberg method is the most conservative but the difference with other methods was approximately 10%. In the cycle histogram, the Dirlik method had more counts than the Lalanne method in lower stress range. However, it does not affect the life of material used in this study. However, if material has a lower fatigue limit or stronger PSD data is used, life difference will occur.
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Scoliosis is a complex musculoskeletal dieses requiring 3-D treatment with surgical instrumentation. To investigate the effects of correction surgery, a finite element model of personalized model of the scoliotic spine that will allow the design of clinical test providing optimal estimation of the post-operation results was developed. Three dimensional skeletal parts, such as vertebrae, clavicle and scapular were modeled as rigid bodies with keeping their morphologies. Kinematical joints and spring elements were adapted to represent the inter-vertebral disc and ligaments respectively. With this model, two types of surgery procedure, distraction procedure with Harrington device and rod derotation procedure with pedicle screw and rod system had been carried out. The obtained simulation results were comparatively corresponding to the post operational outcomes and successfully demonstrated qualitative analysis of surgical effectiveness. From this analysis, it has been found that the preparing of appropriate rod curvature and its insertion was more important than just performing the excessive derotation for scoliosis correction.
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