RELATIONSHIP BETWEEN JOINT ANGLES AND X-FACTOR IN GOLF SWING

The X-Factor is the most commonly investigated performance parameter in the golf. Although there are several studies have reported the relationship between X-Factor and clubhead speed, ball velocity and golfing skills. However, the associated joint kinematics required to attain large X-Factor during the golf swing has received little attention. Therefore, the purpose of current study was to identify the key joint angles that are associated with X-Factor. Ten low handicap male golfers participated in this study. The motion capture system was used to record full body motion. The results indicate the key joints that associate with the X-factor during two phases of swing. This study provides fundamentals of the movement mechanisms of the major joints and their relationship with the X-Factor that can be integrated with coaches and players to improve the golfing skill

Biomechanical Behaviors in Three Types of Spinal Cord Injury Mechanisms

Clinically, spinal cord injuries (SCIs) are radiographically evaluated and diagnosed from plain radiographs, computed tomography (CT), and magnetic resonance imaging. However, it is difficult to conclude that radiographic evaluation of SCI can directly explain the fundamental mechanism of spinal cord damage. The von-Mises stress and maximum principal strain are directly associated with neurological damage in the spinal cord from a biomechanical viewpoint. In this study, the von-Mises stress and maximum principal strain in the spinal cord as well as the cord cross-sectional area (CSA) were analyzed under various magnitudes for contusion, dislocation, and distraction SCI mechanisms, using a finite-element (FE) model of the cervical spine with spinal cord including white matter, gray matter, dura mater with nerve roots, and cerebrospinal fluid (CSF). A regression analysis was performed to find correlation between peak von-Mises stress/ peak maximum principal strain at the cross section of the highest reduction in CSA and corresponding reduction in CSA of the cord. Dislocation and contusion showed greater peak stress and strain values in the cord than distraction. The substantial increases in von-Mises stress as well as CSA reduction similar to or more than 30% were produced at a 60% contusion and a 60% dislocation, while the maximum principal strain was gradually increased as injury severity elevated. In addition, the CSA reduction had a strong correlation with peak von-Mises stress/peak maximum principal strain for the three injury mechanisms, which might be fundamental information in elucidating the relationship between radiographic and mechanical parameters related to SCI

Comparison of Hybrid Localization Methods Using Images and Wi-Fi Signals

Indoor localization is important for many applications, such as navigation, movement tracking, geotagging, and augmented reality. Most studies have used either Wi-Fi or image signals to determine the user’s location. However, each localization method has advantages and disadvantages. In this study, we propose a hybrid localization system combining the advantages of Wi-Fi- and image-based methods. The localization is calculated based on the best four outputs of either image or Wi-Fi localization system. The system was evaluated by comparing the accuracy and unit errors of image-based, Wi-Fi-based, hybrid (image + Wi-Fi), and hybrid (Wi-Fi + image) methods. The results showed accuracies of 77.2%, 49.5%, 73.1%, and 81.6% in the image-based, Wi-Fi-based, hybrid (image + Wi-Fi), and hybrid (Wi-Fi + image) methods, respectively. The hybrid (Wi-Fi and image) method has the lowest error and highest accuracy of the four methods compared. In addition, the image-based localization system shows the highest error, while the Wi-Fi-based localization system shows the lowest accuracy. The robot tests prove that the proposed hybrid system can achieve excellent performance in indoor localization. The proposed hybrid system uses both image processing and Wi-Fi fingerprinting methods to determine the location of the mobile device by creating the two-phase framework, which can help improve the accuracy of indoor localization

Effects of Impactor Size on Biomechanical Characteristics of Spinal Cord in Hemicontusion Injury Model Using Finite Element Analysis

A cervical hemicontusion spinal cord injury (SCI) produces forelimb deficits on the ipsilateral side of the injury while sparing the function of the limbs on the contralateral side of the injury, allowing for the evaluation of experimental therapeutics for functional recovery. Although the effects of contusion force on the functional and behavioral outcomes were adequately described in previous experimental studies, the size of the impactor tip also had significant effects on the extent of the lesion on the contralateral side of the injury in the hemicontusion rat model. However, studies regarding the effects of impactor size on the spinal cord for the hemicontusion model are limited. In this study, a finite element (FE) model of the rat cervical spinal cord was developed to investigate the effects of impactor size in the hemicontusion SCI model on the stress, strain, and displacement of the spinal cord for the New York University (NYU) and Infinite Horizon (IH) impactors. The impactor tip diameters of 1.2 mm and 1.6 mm with high impact loading resulted in the highest stresses and strains in the right (ipsilateral) side of the spinal cord. Thus, impactor tip diameters between 1.2 mm and 1.6 mm would be convenient to use in the rat hemicontusion SCI models for the cervical region without damaging the left (contralateral) side of the spinal cord. Our findings provide an insight into SCI mechanisms in the rat cervical hemicontusion model

Normal Range of Motion of Lower Extremity Joints in Mongolian Subjects

It is important to identify the normal range of motion (ROM) of the human joints for both biomechanical and clinical applications. For health care providers, including physicians and therapists, the restoration of normal ROM is a difficult task. The severity of impaired joint mobility or the postoperative rehabilitation process must be evaluated in comparison with a normal reference value. However, there are no studies that have reported the ROM of Mongolian subjects. In this study, we measured the hip, knee, and ankle joint angles using multiple wearable inertial sensors. Ten healthy young subjects participated. The three-dimensional (3D) motion data were collected while the subject were walking at normal speed. In our knowledge, this study is the first to analyze the normal ROM of Mongolian male subjects. The collected data can be used as reference values for evaluating the disability of the motion and performance in rehabilitation programs