• Safety and Health at Work
• /
• v.13 no.3
• /
• pp.315-325
• /
• 2022

Background: Firefighters are required to carry self-contained breathing apparatus (SCBA), which increases the risk of musculoskeletal disorders. This study assessed the newly recruited firefighters' internal forces and potential musculoskeletal disorders when carrying SCBA. The effects of SCBA strap lengths were also evaluated. Methods: Kinematic parameters of twelve male subjects running in a control condition with no SCBA equipped and three varying-strapped SCBAs were measured using 3D inertial motion capture. Subsequently, motion data and predicted ground reaction force were inputted for subject-specific musculoskeletal modeling to estimate joint and muscle forces. Results: The knee was exposed to the highest internal force when carrying SCBA, followed by the rectus femoris and hip, while the shoulder had the lowest force compared to the no-SCBA condition. Our model also revealed that adjusting SCBA straps length was an efficient strategy to influence the force that occurred at the lumbar spine, hip, and knee regions. Grey relation analysis indicated that the deviation of the center of mass, step length, and knee flexion-extension angle could be used as the predictor of musculoskeletal disorders. Conclusion: The finding suggested that the training of the newly recruits focuses on the coordinated movement of muscle and joints in the lower limb. The strap lengths around 98-105 cm were also recommended. The findings are expected to provide injury interventions to enhance the occupational health and safety of the newly recruited firefighters.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.84-87
• /
• 2009

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.9
• /
• pp.866-871
• /
• 2010

Gait analysis is essential for leg diagnosis and rehabilitation for the patients, the handicapped and the elderly. The use of 3D motion capture device for gait analysis is very common for gait analysis. However, this device has several shortcomings including limited workspace, visibility and high price. Instead, we developed gait estimation system using gyroscopes. This system provides gait information including the number of gaits, stride and walking distance. With four gyroscope (one for each leg's thigh and calf) outputs, the proposed gait modeling estimates the movements of the hip, the knees and the feet. Complete pedestrian localization is implemented with gait information and the heading angle estimated from the rate gyro and the magnetic compass measurements. The developed system is very useful for diagnosis and the rehabilitation of the pedestrian at the hospital. It is also useful for indoor localization of the pedestrians.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.10 no.1
• /
• pp.101-106
• /
• 2016

In this paper, we analysed correlation between scores and posture of amateur archer with inertial sensor based motion analysis system. Four 13 to 15 yeared subjects are participated and accelerations of upper and forearms are measured during shooting. Each subject carried out six end. And they shoot arrows six times per each end from 30 meters away. We extracted and analyzed acceleration values during full throw. In the case of left arm, we could not found any meaningful correlation with score. Meanwhile, acceleration values of right arm have certain correlation with score. It seems that aiming skill of right arm is very important while left arm settles stably.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.1-8
• /
• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• Cartoon and Animation Studies
• /
• s.28
• /
• pp.125-153
• /
• 2012

This study is regarding what motion modality has influences on aspects of genre and media. Nowadays, motion modality becomes an element which is actively manipulated in live actions as well as animations. And, it has been generally accepted that a strategy on manipulation of motion depends on matters of genre or medium. As respected, can we say the premise is correct? if it is, can we refine the premise more theoretically, without using the words, 'genre' or 'media' which have not been are not been defined on an academic aspect. I intend to discuss on this issue. I will speculate the issue of manipulation of motion modality on theoretical bases. According to McLuhan's hot/cool media theory and Bolter's oscillation theory, the effect of it turns out to be same as manipulation of sentience ratio of media readers, and the ideal result will be examined by an example analysis. In the analysis, I will explore what effects manipulation of motion has on several examples. Then, by examining what kind of correlation these effects has with media/genre positioning, I ultimately will evaluate the genre/medium-based determinism of motion modality, which is represented by a typical premise like "Animation is most realistic when it has the most animation-like movement." Conclusively I suggest a refined premise like the following. Modality of motion is a strategy depending on issues of genre, with no regard to issues of medium, and the issue of genre is a category which is positioned considering mixture ratio of sentience. With this reason, A strategy of modality of motion depends to sentience a certain sequence needs. So, motion modality becomes a strategy which has to be approached in functionality of genre rather than economic values which spring from technical devices like a motion capture.

• Physical Therapy Korea
• /
• v.27 no.4
• /
• pp.227-232
• /
• 2020

Background: Hallux valgus (HV) is a foot deformity developed by mediolateral deviation of the first metatarsophalangeal joint. Although various foot-toe orthoses were used to correct the HV angle, verification of the effects of kinetics variables such as ground reaction force (GRF) through three-dimensional (3D) gait analysis according to the various type of orthoses for HV is insufficient. Objects: This study aimed to investigate the effect of soft and hard types of foot and toe orthoses to correct HV deformity on the GRF in individuals with HV using 3D motion analysis system during walking. Methods: Twenty-six subjects participated in the experiment. Participants had HV angle of more than 15° in both feet. Two force platforms were used to obtain 3D GRF data for both feet and a 3D motion capture system with six infrared cameras was used to measure exact stance phase point such as heel strike or toe off period. Total walk trials of each participant were 8 to 10, the walkway length was 6 m. Two-way repeated measures ANOVA was used to determine the effects of each orthosis condition on the various GRF values. Results: The late anteroposterior maximal force and a first vertical peak force of the GRF showed that the hard type orthosis condition significantly increased GRF compared to the other orthosis conditions (p < 0.05). Conclusion: There were significant effects in GRF values when wearing the hard type foot orthosis. However, the hard type foot orthosis was uncomfortable to wear during walking. Therefore, it is necessary to develop a new foot-toe orthosis that can compensate for these disadvantages.

• Annals of Rehabilitation Medicine
• /
• v.42 no.6
• /
• pp.872-883
• /
• 2018

Objective To replace camera-based three-dimensional motion analyzers which are widely used to analyze body movements and gait but are also costly and require a large dedicated space, this study evaluates the validity and reliability of inertial measurement unit (IMU)-based systems by analyzing their spatio-temporal and kinematic measurement parameters. Methods The investigation was conducted in three separate hospitals with three healthy participants. IMUs were attached to the abdomen as well as the thigh, shank, and foot of both legs of each participant. Each participant then completed a 10-m gait course 10 times. During each gait cycle, the hips, knees, and ankle joints were observed from the sagittal, frontal, and transverse planes. The experiments were conducted with both a camera-based system and an IMU-based system. The measured gait analysis data were evaluated for validity and reliability using root mean square error (RMSE) and intraclass correlation coefficient (ICC) analyses. Results The differences between the RMSE values of the two systems determined through kinematic parameters ranged from a minimum of 1.83 to a maximum of 3.98 with a tolerance close to 1%. The results of this study also confirmed the reliability of the IMU-based system, and all of the variables showed a statistically high ICC. Conclusion These results confirmed that IMU-based systems can reliably replace camera-based systems for clinical body motion and gait analyses.

• Coupled systems mechanics
• /
• v.7 no.2
• /
• pp.111-139
• /
• 2018

A successful methodology for modelling controlled destruction and progressive collapse of 2D reinforced concrete frames is presented in this paper. The strategy is subdivided into several aspects including the failure mechanism creation, and dynamic motion in failure represented with multibody system (MBS) simulation that are used to jointly capture controlled demolition. First phase employs linear elasto-plastic analysis with isotropic hardening along with softening plastic hinge concept to investigate the complete failure of structure, leading to creation of final failure mechanism that behaves like MBS. Second phase deals with simulation and control of the progressive collapse of the structure up to total demolition, using the nonlinear dynamic analysis, with conserving/decaying energy scheme which is performed on MBS. The contact between structure and ground is also considered in simulation of collapse process. The efficiency of the proposed methodology is proved with several numerical examples including six story reinforced concrete frame structures.

• Korean Journal of Applied Biomechanics
• /
• v.31 no.1
• /
• pp.44-49
• /
• 2021

Objective: The purpose of this study was to analyze kinematic variables according to ground slope angle during golf putting. Method: 26 collegiate golfers (age: 22.54±2.15 kg, height: 174.64±6.07 cm, weight: 71.35±9.27 kg, handicap: 5.11±4.50) were participated, and 8 motion capture cameras (250 Hz), Nexus, and Kwon3DXP software were used to collect data. It was performed repeated measures ANOVA and Bonferroni adjustment. Alpha set at .05. Results: Body alignments were not significantly different at address. Putter head trajectory and loft angle were significantly different, and AP direction of acceleration of putter head was significantly different. However, ML and SI direction of acceleration of putter head were not significantly different. Conclusion: Therefore, it was identified that ground slope angle was affected the kinematic variables during putting, and it will be performed that correlation analysis between putting success rate and kinematic variables according to ground slope angle during golf putting.