• Journal of the Korean Society of Visualization
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• v.16 no.2
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• pp.31-37
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• 2018

Ischemic mitral regurgitation (IMR) is the primary mitral valve (MV) pathology in the aftermath of myocardial infarction as a consequence of regional left ventricular (LV) remodeling. We investigated the effect of asymmetric papillary muscle (PM) displacement and annular dilation on IMR development. Virtual MV modeling was performed to create a normal human MV. Asymmetric PM displacement, asymmetric annular dilation, and the combination of these two pathologic characteristics were modeled. Dynamic finite element evaluation of MV function was performed across the complete cardiac cycle for the normal and three different IMR MV models. While the normal MV demonstrated complete leaflet coaptation, each pathologic MV model clearly revealed deteriorated leaflet coaptation and abnormal stress distributions. The pathologic MV model having both asymmetric PM displacement and annular dilation showed the worst leaflet malcoaptation. Simulation-based biomechanical evaluation of post-ischemic LV remodeling provides an excellent tool to better understand the pathophysiologic mechanism of IMR development.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.195-202
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• 2006

The degenerative lumbar spinal stenosis (DLSS) is a disease inducing low back pain, leg pain, convulsion. numbness, and neurogenic claudication from compression of nerve root. Intervertebra fixation was reported to increase the degeneration of neighbor lesion after treatment. Recently, a new surgical technique of inserting a fixator between interspinous processes has been introduced. The purpose of this study is to design the interspinous process fixator with flexibility to complement the trouble of using fixator in DLSS. This study evaluated the existing fixator through the mechanical test and modified it using the finite element analysis (FEA). The evaluation was based on the displacement, stiffness and von-Mises stress obtained from the mechanical test and calculated from the FEA in the biomechanical loading condition. Effects of variation in length and thickness were investigated to design an optimal fixator. Three prototypes were manufactured using FEA results. Mechanical tests under the biomechanical loading condition were performed to select the best one from these three. The selected fixator increased flexiblity by 32.9%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1489-1490
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.997-998
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1419-1420
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• 2011

• Advances in biomechanics and applications
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• v.1 no.4
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• pp.239-252
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• 2014

This study aimed to assess the biomechanical performance of a new generation of artificial ligament, which can be considered "bioactive" and "biointegrated," implanted in sheep. Thirty sheep were implanted: 15 sheep received the artificial ligament grafted with a bioactive polymer (grafted) and 15 received the artificial ligament without a bioactive polymer (non-grafted). The animals were sacrificed 3 or 12 months after implantation. The knee kinematics, namely flexion-extension, anterior drawer, and varus-valgus tests, were evaluated using a fully characterized custom-made device. Afterward, the specimens were tested under uniaxial tension until failure. The flexion-extension showed significant differences between (grafted or non-grafted) artificial and native ligaments 3 months after implantation. This difference became non-significant 12 months postoperatively. The anterior tibial drawer was significantly increased 3 months after implantation and remained significantly different only for non-grafted ligament 12 months after implantation. Twelve months after implantation, the differences between grafted and non-grafted ligament biomechanical properties were significant in terms of stiffness. In terms of load to failure, grafted ligaments seem to have had slightly better performance than non-grafted ligaments 12 months postoperatively. Overall these results suggest that grafted artificial ligaments have slightly better biomechanical characteristics than non-grafted artificial ligaments 12 months after implantation in sheep.

• Journal of Biomedical Engineering Research
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• v.34 no.1
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• pp.14-23
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• 2013

In this study, biomechanical stability of the newly developed revision total knee arthroplasty (rTKA) was evaluated through strain and stress distribution analysis within the implanted proximal tibia using a three-dimensional finite element (FE) analysis. 2000N of compressive load (about 3 times body weight) was applied to the condyle surface on spacer, sharing by the medial (60%) and lateral (40%) condyles simulating a stance phase before toe-off. The results showed that PVMS within the revision total knee arthroplasty and the proximal tibia were less than yield strength considering safe factor 4.0 (rTKA: less than 10%, Cortical bone: less than 70%, Cancellous bone: less than 70%). The materials composed of them and the strain and stress distributions within the proximal tibia were generally well matched with those of a traditional revision total knee arthoplasty (Scorpio TS revision system, Stryker Corp., Michigan, USA) without the critical damage strain and stress, which may reduce the capacity for bone remodeling, leading to bone degeneration. This study may be useful to design parameter improvement of the revision total knee arthoplasty in biomechanical stability point of view beyond structural stability of revision total knee arthoplasty itself.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.27-32
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• 2004

In this study, method of PMMA injection is suggested for vertebroplasty in patients with osteoporotic compression fracture. The finite element analysis is used to investigate the vertebroplasty quantitatively. In order to improve previous works with simplified geometry of vertebral body more exact geometry has been constructed from CT image data with 1m thickness. An ideal method of PMMA delivery, with respect to location and amount of injectate, into vertebral body has been suggested based on evaluation of the insert positions and the insert shapes of injected PMMA. It is shown that vertebral body can be compensated most efficiently when PVIMA is highly concentrated on the top-front of trabecular bone of compressed vertebra.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.2
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• pp.40-52
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• 2000

The aim of this study was to evaluate the prevailing ergonomic conditions regarding low back injury in an assembly factory, In this study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 10 jobs with greater back compressive forces than 350kg at L5/S1. Also there were 44 jobs over Action Limit in terms of 1981 NIOSH guidelines. This could in part be explained by the ergonomic conditions of the companys analysed as not hazardous, with a relatively low duration of 'combined' extreme work posture. However, more ergonomic intervention could be done based on those results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.555-556
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• 2006