• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.587-597
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• 2007

Steel restrainer cables for multiple frame bridges in California in the United States have been shown to be effective in preventing unseating at internal hinges during the past several earthquakes. Consequently, the steel-cable-restrainer is being tested for applications on multiple-span-simply-supported (MSSS) bridges in the mid-American region. In addition, shape memory alloy (SMA) bars in tension are being studied for the same application, multiple frame bridges, the developed seismic forces are transferred to piers through the restrainers. However, in MSSS bridges, the seismic forces are transferred to abutments by the restrainers. Therefore, the abutment' behavior should also be investigated. In this study, we assessed the seismic performance of the three types of restrainers, such as steel restrainer cables, SMA in tension, and SMA in bending for an MSSS bridge from moderate to strong ground motion, bending test of an SMA bar was conducted and its analytical model was determined for this study. Nonlinear time history analyses were conducted to assess the seismic responses of the as-built and the retrofitted bridges. All three types of restrainers reduced the hinge opening and the SMA in tension was the most effective of the three devices in preventing the unseating, all restrainers produced damage on the abutment from the pulling action of the MSSS bridge due to strong ground motions, was found that the retrofit of the abutment in the pulling action is required in the installation of restrainers in MSSS bridges.

• Journal of Korean Physical Therapy Science
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• v.31 no.1
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• pp.16-32
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• 2024

Background: Exercise equipments and assistive devices for the disabled are being developed, but improvements for usability are still needed. The purpose of this study was to improve and utilize the developed exercise equipment and assistance devices by conducting usability test for people with spinal cord injury. Design: Cross-sectional Study. Methods: Scenarios and usability indicators were derived by conducting a preliminary usability test, 5 non-disabled men and women aged 19 or older. In the scenario, a total of 9 tasks were sequentially performed, including 2 tasks of entry and exit, 5 tasks of assistance devices and weight stack adjustment, and 2 tasks of pre exercise and exercise. The usability indicators were task success (success or fail), execution time (sec), safety, and convenience. For safety, 7 questions (Likert scale, 1~5 point) related to safety, stability and hazard were derived, and for convenience, the system usability scale (SUS score) was used (range: 0~100, 50 percentile rank is 68 point). Results: As a result of the usability test of people with spinal cord injury, there was a large variation among subjects in the task of adjusting the position of the pulley and support in the execution time (11.64~25.44 seconds), and one person failed to adjust the pulley. The safety level showed a lower score (score = 3 points) than other items in the item of entrapment or skin pressure, and in the case of SUS, the average score was 64.5 points, which was close to the acceptable level. Conclusion: Through the usability test, it was confirmed that exercise equipment for the disabled needs improvement in operability, pinching, and pressure, and that it is necessary to develop an assistive device that provides unrestrained posture information (biofeedback) to maintain correct posture during exercise.