• BMB Reports
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• v.56 no.5
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• pp.287-295
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• 2023

The tumor microenvironment (TME) is a complex system composed of many cell types and an extracellular matrix (ECM). During tumorigenesis, cancer cells constantly interact with cellular components, biochemical cues, and the ECM in the TME, all of which make the environment favorable for cancer growth. Emerging evidence has revealed the importance of substrate elasticity and biomechanical forces in tumor progression and metastasis. However, the mechanisms underlying the cell response to mechanical signals-such as extrinsic mechanical forces and forces generated within the TME-are still relatively unknown. Moreover, having a deeper understanding of the mechanisms by which cancer cells sense mechanical forces and transmit signals to the cytoplasm would substantially help develop effective strategies for cancer treatment. This review provides an overview of biomechanical forces in the TME and the intracellular signaling pathways activated by mechanical cues as well as highlights the role of mechanotransductive pathways through mechanosensors that detect the altering biomechanical forces in the TME.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.1-6
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• 2009

Recently, importance of the rehabilitation of hand pathologies as well as the development of high-technology hand robot has been increased. The biomechanical model of hand is indispensable due to the difficulty of direct measurement of muscle forces and joint forces in hands. In this study, a three-dimensional biomechanical model of four fingers including three joints and ten muscles in each finger was developed and a mathematical relationship between neural commands and finger forces which represents the enslaving effect and the force deficit effect was proposed. When pressing a plate under the flexed posture, the muscle forces and the joint forces were predicted by the optimization technique. The results showed that the major activated muscles were flexion muscles (flexor digitorum profundus, radial interosseous, and ulnar interosseous). In addition, it was found that the antagonistic muscles were also activated rather than the previous models, which is more realistic phenomenon. The present model has considered the interaction among fingers, thus can be more powerful while developing a robot hand that can totally control the multiple fingers like human.

• Journal of the Ergonomics Society of Korea
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• v.1 no.2
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• pp.3-9
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• 1982

This study demonstrates that certain personal and task factors can be modelled to predict slip potential as well as back loadings durings dynamic pushing and pulling tasks. Such tasks are com- mon to many manual material handling jobs in industry and the results of this work will hopefully be of use in improved job design. The objective of this research is to formulate and validate a dynamic biomechanical model of pushing and pulling a cart. For pushing and pulling tasks, the model can : (1) estimate foot forces for given hand forces, and (2) estimate tors muscle and vertabral column loadings. In order to formulate and validate the model, experiments involving pushing and pulling of a cart were performed. These experiments produced data of the following type : (1) dynamic forces on the feet, (2) hand forces required to move the cart, (3) body motions as functions of various cart motion and (4) back muscle actions. The model was validated using three different methods; precision was tested using correlation between predicted and measured results, accuracy using standard error between of predicted and measured results, and intuitive comparison of predicted results using sensitivity analyses.

• International Journal of Stem Cells
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• v.16 no.3
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• pp.251-259
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• 2023

Mesenchymal stromal cells (MSCs) have attracted scientific and medical interest due to their self-renewing properties, pluripotency, and paracrine function. However, one of the main limitations to the clinical application of MSCs is their loss of efficacy after transplantation in vivo. Various bioengineering technologies to provide stem cell niche-like conditions have the potential to overcome this limitation. Here, focusing on the stem cell niche microenvironment, studies to maximize the immunomodulatory potential of MSCs by controlling biomechanical stimuli, including shear stress, hydrostatic pressure, stretch, and biophysical cues, such as extracellular matrix mimetic substrates, are discussed. The application of biomechanical forces or biophysical cues to the stem cell microenvironment will be beneficial for enhancing the immunomodulatory function of MSCs during cultivation and overcoming the current limitations of MSC therapy.

• The korean journal of orthodontics
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• v.47 no.5
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• pp.289-297
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• 2017

Objective: The objective of this study was to analyze the patterns of tooth movements when distalization of mandibular molars using a mini-plate took place. A finite element analysis was applied to analyze patterns of tooth movements. Methods: The model of the mandible and teeth were used to build a finite element analysis model, and a mini-plate was inserted in the mandibular ramus. Two different orthodontic forces were established for displacement of mandibular molars. Orthodontic forces were applied at the level of the bracket and at the level of the cemento-enamel junction in the mandibular canine respectively. Results: Applying orthodontic forces at the level of the cemento-enamel junction resulted in a greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of the bracket. Applying orthodontic forces to the cemento-enamel junction also resulted in unwanted greater extrusive movements in distalization of the mandibular molars compared to the bracket level. Conclusions: With considering the mode of orthodontic teeth movement, applying different vertical orthodontic forces for distalization of mandibular molars can lead to more effective distalization of teeth.

• Korean Journal of Computational Design and Engineering
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• v.13 no.1
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• pp.58-66
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• 2008

The artificial discs have recently used to preserve the motion of the treated segment in lumbar spine surgery. However, there have been lack of biomechanical information of the artificial discs to explain current clinical controversies such as long-term results of implant wear and excessive facet contact forces. In this study, we investigated the biomechanical effects of three artificial implants on the lumbar spinal segments by finite element analysis. The finite element model of intact lumbar spine(L1-S) was developed and the three implants were inserted in L4-L5 segment of the spine model. 5 Nm of flexion and extension moments were applied on the superior plate of L1 with 400 N of compressive load. Excessive motions and high facet contact forces at the surgical level were generated in the all three implanted models. In the flexion, the peak von-Mises stresses in the semi-constrained type implant was higher than those in the un-constrained type implant which would cause wear on the polyethylene core. The results of the study would provide a biomechanical guideline for selecting optimal surgical approach or evaluating the current design of the implants, or developing a new implant.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1990.04a
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• pp.140-150
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• 1990

Further developments on a dynamic biomechanical model are presented to assess musculoskeletal stresses and human responses. The model being developed is an extension of the Articulated Total Body (ATB) Model, originally developed by Calsapan Corp. for the study of human dynamics during automobile crashes, later adopted to the U.S.Air Force to simulate the reactions of aircrew personnel to such forces typically encountered in various phases of flight operations. Further refinements were introduced by Freivalds and Kaleps(1984) to account for a human neuromusculature. In this study, modelling of active neuromusculature was described and simulations of whole-body human motion were performed using the ATB Model. It indicated the potential of using a muscularized biomechanical model coupled with CAD capabilities to simulate human responses in a variety of industrial settings as well. This will serve as a basis of incorporating computer aided design methods into a muscularized biomechanical models.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1864-1873
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• 1993

A biomechanical approach was carried out to analyze foot-floor reaction forces acting on five male subjects performing a walking task. The task analyzed was walking over an obstacle with the right bare foot. The foot-floor reaction data were measured from a force plate, and then processed using a software developed. The source program was coded in the C language for easier on-line data acquisition and graphic displays. High repeatability was found in the reaction data acquired from three trials by each subject. For obstacle height from 0 to 25 cm, the maximum in reaction force reached up to 1.048 BW in the vertical, 0.174 BW in the anterior-posterior, and 0.054 BW in the medio-lateral components, respectively. A quantity was defined by the difference between two vertical reaction values, and this quantity was found to be proportional to the obstacle height. It was also shown that the whole body motion could be predicted the measured foot-floor reaction data.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.4
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• pp.207-223
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• 2015

In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.83-92
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• 2016

Objective: This study aimed to compare differences in biomechanical factors according to distance changes in relation to approaches during a round of golf to obtain basic data on golf swings. Methods: The research subjects were 8 KPGA-affiliated professional golfers who performed approach shots that put a ball into a circle of 8 feet in diameter from distances of 30, 50, and 70 m. Data were collected by using six infrared cameras and a ground reaction force device, which were applied to calculate biomechanical factors by using Kwon3D XP. The calculated data were subjected to one-way ANOVA by using SPSS 20.0, with the significance level set at p value of 0.05. Results: Elapsed time, stance width, clubhead position variation, clubhead synthesis speed, and cocking angle significantly differed according to distance change during the approach swing. Clubhead speed was positively related with stance width and clubhead displacement. Ground reaction force significantly differed according to distance change during the approach swing. Factors before and after showed differences in other states, except in the impact state. Conclusion: In the present study, we drew several conclusions regarding biomechanical factors and ground reaction forces according to distance change in the approach swing of professional golfers. According to these conclusions, we suggest that distance control with swing range is more important than power control in maintaining the accuracy and consistency of golf swing and is the most important mechanism of golf swing.