David Michael M I C H A E L O'Sullivan | Seoul National University (original) (raw)

Papers by David Michael M I C H A E L O'Sullivan

Korean Journal of Sport Biomechanics, Jun 1, 2019

Aquatic exercise therapy has been shown to be an effective exercise method to maintain health and... more Aquatic exercise therapy has been shown to be an effective exercise method to maintain health and help rehabilitation in diverse groups such as patients with arthritis, hemiplegic, injured athletes, and the elderly. By applying the body movement which is free from the stresses of exercising on ground, water has the merit that it enables more free movement all while maintaining water resistance which helps build and maintain muscle (Koury, 1996). In Korea, interest in aquatic exercises and therapy have been rapidly increasing since the 1990s, focusing mainly in the welfare centers for the disabled and the older (over 65 years of age) population (Kim, Moon, & Yu, 2014). Recently, several researchers have conducted various studies on the effect of underwater rehabilitation exercise, and reported on the positive effect of improving physical strength and walking ability through aquatic

International Journal of Information and Communication Technology Education, Jul 12, 2021

The objectives of this study were to investigate the feasibility of applying computer vision tech... more The objectives of this study were to investigate the feasibility of applying computer vision techniques and to analyse changes in behaviour and movement of high school students during class. The study was performed over two phases. Phase 1 focused on developing a feasible method to use computer vision-based techniques in high school classes, and Phase 2 focused on the testing of aromatherapy to affect student movement. All camera data was processed and analysed by OpenPose, Matlab, and EyesWeb. Movement features such as velocity, acceleration, and kinetic energy and postural variables, spinal extension, and neck flexion were calculated. Results of Phase 1 showed significant differences in the overall segment velocity, acceleration, energy, and neck flexion. Similarly, the second phase showed significant differences in velocity, acceleration, and jerk for the left shoulder and elbow joints of the group exposed to aroma. In conclusion, the results show the feasibility of using computer vision techniques in a classroom setting.

ISBS - Conference Proceedings Archive, 2012

The purpose of this study was to investigate gait patterns of children with autism using temporal... more The purpose of this study was to investigate gait patterns of children with autism using temporal-spatial and foot pressure variables. A total of 30 children participated; 15 autistic children and 15 age matched controls. Group differences were tested using an independent t-test performed by SPSS. The cadence and step/extremity ratio was significantly lower for the experimental group than the control group. The step width was wider; while cycle time, double support time, stance time was longer for the experimental group. The active pressure area and maximum pressure in the hind foot were lower for the experimental group. There were reduced gait velocities and reduced pressure areas in the hind foot and mid foot.

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2020

Concern about the consequences of head impacts in US football has motivated researchers to invest... more Concern about the consequences of head impacts in US football has motivated researchers to investigate and develop instrumentation to measure the severity of these impacts. However, the severity of head impacts in unhelmeted sports is largely unknown as miniaturised sensor technology has only recently made it possible to measure these impacts in vivo. The objective of this study was to measure the linear and angular head accelerations in impacts in mixed martial arts, and correlate these with concussive injuries. Thirteen mixed martial arts fighters were fitted with the Stanford instrumented mouthguard (MiG2.0) participated in this study. The mouthguard recorded linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. A total of 451 verified head impacts above 10g were recorded during 19 sparring events (n = 298) and 11 competitive events (n =...

Physical education in the United States underwent a massive overhall of curriculum in the 1960s l... more Physical education in the United States underwent a massive overhall of curriculum in the 1960s leading to theory based curricula and a more scientific foundation of principles. From two international faculty members of one department of physical education in Korea, we present a comparison of well known exercise and sport science programs from two Western universities (Republic of Ireland and the United States of America). From this comparison we provide suggestions for improvement of curriculum and overall learning objectives for Korean institutions.

This is the first known laboratory study comparing head impacts among junior and senior amateur b... more This is the first known laboratory study comparing head impacts among junior and senior amateur boxers. The results indicate that young boxers impart larger impacts than their older counterparts in this cohort. It is alarming that the junior boxers recorded impacts similar to those of their Olympic counterparts.

The objective was to compare head impacts by junior and senior taekwondo athletes following a tur... more The objective was to compare head impacts by junior and senior taekwondo athletes following a turning kick. It is worrisome that junior athletes may be subject to similar impacts produced by adult competitors. This study provides a glimpse into the possible impacts of rotational velocities experienced during full-contact competition. These data may provide a stepping-stone towards developing more age-specific designs for protective headgear.

Computer Methods in Biomechanics and Biomedical Engineering, 2020

This study determined brain stress and strain in an unhelmeted sport and correlated this with con... more This study determined brain stress and strain in an unhelmeted sport and correlated this with concussive injuries. Thirteen MMA athletes were fitted with the MiG2.0 Stanford instrumented mouthguard. The mouthguard records linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. 298 impacts above 10g were recorded during sparring sessions and 153 impacts in competitive events. The competitive events resulted in five concussions which were diagnosed by a medical doctor. The impact with the highest angular acceleration from each sparring session and competitive event was simulated using the GHBMC head and neck model. The model was run on Amazon Web Services using the LS-Dyna explicit solver. The resultant linear acceleration, strain in the corpus callosum and brain stem and shear stress in the corpus callosum were all significantly different in concussed athletes compared to uninjured. Average strain in the corpus callosum of concussed fighters was 0.27 which was 87.9% higher than uninjured fighters and was the best strain indicator of concussion. The best overall predictor of concussion found in this study was shear stress in the corpus callosum which differed by 111.4% between concussed and uninjured athletes. This study is unique in that it measured head accelerations in vivo and determined that high stress and strain in the corpus callosum correlated with the concussive injuries.

Central European Journal of Sport Sciences and Medicine, 2015

Objective: To assess taekwondo sparring performance variables, such as joint ranges of motion, re... more Objective: To assess taekwondo sparring performance variables, such as joint ranges of motion, reaction times, and kicking foot speeds, to serve as a framework for developing sport-specific classification in Para-taekwondo competition. Methods: After a standard taekwondo warm up, athletes executed five popular scoring techniques, back kick, cut kick, fast kick, turning kick, and tornado kick five times each (25 total). Kinematic and kinetic variables were recorded by a motion capture system of seven infrared cameras and two force plates. Maximum joint range of motion, foot velocities, and reaction time were calculated.

The Official Journal of the Korean Academy of Kinesiology, 2017

The purpose was to present incidence of injuries for injuries at an international competition [ME... more The purpose was to present incidence of injuries for injuries at an international competition [METHODS] The study was designed as a prospective observational epidemiological study, set at the 6 th World Para-taekwondo Championships, with 92 males (28.8 +5.7years, 178.3+4.7cm, 73.0+9.6kg) and 21 females (28.6+6.6years, 163.3+4.1cm, 52.6+2.6kg) participating. During the championships musculoskeletal injury data were collected and analyzed. The main outcome measures were the injury incidence rate with 95% confidence intervals (CI). [RESULTS] The overall injury incidence was 49.8 per 1000 athlete exposures (A-E) (95% CI: 16.7 to 80.0) and 24.6 per 1000 minute exposures (M-E) (95% CI: 8.5 to 40.6). Contusions were the predominant injury type (21.5, 95 % CI = 0.43 to 42.6: 10.9 injuries per 1000 ME , 95 % CI = 0.22 to 21.6). The total concussion incidence was 21.5 per 1000 A-E (95% CI:-5.1 to 15.9) and 10.64 per 1000 ME (95% CI:-2.6 to 8.1). Males had an incidence of severe injury of 22.0 per 1000 (5.8 to 38.7) ME and females had an incidence moderate injury of 3.2 per 1000 (-3.0 to 9.4) ME. [CONCLUSION] Contrary to previous taekwondo injury studies, ligament sprains were more common than contusions and therefore, extra attention may be warranted to prevent non-contact injuries.

The Asian Journal of Kinesiology

BACKGROUND Maintaining muscle mass and an efficient cardiovascular system is vital for healthy ag... more BACKGROUND Maintaining muscle mass and an efficient cardiovascular system is vital for healthy aging.OBJECTIVES This study investigates if a low intensity senior strength exercise program for the older females can have an effect cardiovascular function and improve senior functional fitness.METHODS There were 22 older females, randomly divided into a strength exercise (age: 72.18 ± 4.97 yrs; height: 1.54 ± 0.06 m; weight: 58.02 ± 7.29 kg; BMI:24.43 ± 2.69 kg/m2) and control group (age: 77.63 ± 4.96 yrs; height: 1.51 ± 0.05 m; weight: 53.66 ± 6.62 kg; BMI:23.54 ± 2.22 kg/m2). The strength exercise group participated three times per week for 20 weeks, while the control group did not do any additional treatment or exercise. Participants were tested pre and post strength exercise, and the data were statistically analyzed using two-way repeated measures Analysis of Variance (ANOVA), with a significance level of p <0.05.RESULTS The results show significant differences (p<0.001) in ho...

Healthcare

Para taekwondo is a combat sport martial art that requires fast reaction times for successful def... more Para taekwondo is a combat sport martial art that requires fast reaction times for successful defense during fighting. The current classification system is based on the function and the effective length of the upper limbs, which affects the athlete’s ability to block. Therefore, this study aimed to investigate the differences between the different classes in the athlete’s ability to block and move around the ring. A total of 87 Para taekwondo (K42, K43, and K44) athletes’ data were analyzed. Each participant engaged in the blocking reaction time test in a fighting stance with the left leg in front, the right leg in front, and the legs parallel in random order. A foot-stepping reaction test was performed to anlyze how the athletes moved in various directions. The results indicated no significant differences between the classes for the lower body foot stepping reaction times and the upper body blocking performance times. The stimulated blocking time of the Para taekwondo athletes rang...

Human Movement, 2021

Purpose. The purpose of this study was to investigate the effect of stress on movement before and... more Purpose. The purpose of this study was to investigate the effect of stress on movement before and after a computer, application-based simulated stress task. Methods. Differences in the movement of participants was examined by measuring movement quality described by wrist accumulated distance, velocity, acceleration, jerk, and smoothness. Ten high school students performed three horizontal and vertical hand circling movements before and after a simulated concentration-based stress task. Blood pressure was measured, and a saliva sample was collected before and after stress test execution. Participants were instructed to take a 10 minutes relaxation period, perform three horizontal and vertical circling movements, a 20minute stress task, and then perform three horizontal and vertical movements. Results. There were significant differences between before and after the stress task in the level of cortisol (p<0.05), heart rate (p<0.01), smoothness (p<0.01) and jerk movements (p<0.05) in the vertical plane. The stress-related variables were lower after the relaxation phase than the stress task. Likewise, movements were smoother and had less jerk in the vertical plane after relaxation. Conclusions. This study indicates the possibility that stress may affect hand movement quality in the vertical plane and therefore, we recommend that any movement behavior adaptive therapy should focus on movements in the vertical plane.

The Asian Journal of Kinesiology, 2018

Research investigating head injury mechanics during practice and competition are underway in spor... more Research investigating head injury mechanics during practice and competition are underway in sports, such as ice hock-ey1, American football [2,3], soccer [4], boxing [5], and taekwondo[6]. With the different head protective requirements of each of these sports various head impact monitors for helmets and non-helmeted sports have been developed [7,8]. The Head Impact Telemetry (HIT) system (Simbex; Lebenon, USA) developed in 2003, which incorporates a nine-accelerometer array has been mainly in American gridiron football [2,3,8] and ice-hockey [1], but also been modified for use in soccer [4] and boxing [9]. Another head impact measuring device designed for use in helmeted sports the GForceTracker (GFT, Ontario, Canada) can be attached to different helmets [10]. The GFT samples linear accelerations at 3000 Hz and angular velocity at

BACKGROUND Depression is a severe illness that has accelerated with the spread of COVID-19 and as... more BACKGROUND Depression is a severe illness that has accelerated with the spread of COVID-19 and associated lockdowns. As a result, reported physical activity has substantially decreased, further increasing depressive symptoms. OBJECTIVE We aimed to explain the use of gamification principles to develop content for an interactive physical activity game for depression based on clinically proven depression diagnostic criteria. METHODS In the first part, we discuss related work in this field, the game design framework, the users’ depression severity, how we customize the contents accordingly, the gradual progression of the game to match exercise principles, and user flow optimization. RESULTS In this section, we provide a brief description of each of the games developed, including instructions on how to play and design aspects for flow, audio, and visual feedback methods. Interactive physical activity-based games stimulate certain physical fitness factors such as improving reaction time, ...

Journal of Men’s Health, 2021

Background and Objective: The objective of this study was to investigate various issues surroundi... more Background and Objective: The objective of this study was to investigate various issues surrounding participation in Para-Taekwondo Kyorugi (sparring), with the aim of focusing on future research initiatives to improve the classiﬁcation system and safety for participation in Para-Taekwondo. Material and Methods: For this, a series of online questionnaires and in-person round-table discussions were conducted prior to the World Para-Taekwondo Championships (Antalya, Turkey, 2019), with a ﬁnal online questionnaire thereafter. A select group of experts, such as athletes, coaches, administrators, classiﬁers, and athletes were invited to partake, with the main outcome measures being the expert opinions and ranking of importance for research into issues affecting Para Taekwondo athletes. Results: The results of the discuss provide suggestions and opinions for the following areas are provided for the aim of classiﬁcation, minimum impairment criteria, fairness of classes, combination of clas...

The Asian Journal of Kinesiology, 2021

BACKGROUND Current research on genu varum shows the favorable influence of exercise on the biomec... more BACKGROUND Current research on genu varum shows the favorable influence of exercise on the biomechanics of the knee joint by reducing the static malalignment and mechanical imbalances, however the transference to a more optimum gait has not been investigated.OBJECTIVES To investigate the effects of Pilates exercise on the changes of gait and lower limb malalignment in female students with genu varum.METHODS A total of 23 female college students with verified genu varum participated in this study. The participants were randomly assigned to two groups a Pilates exercise group (n=15) and a control group (n=8). The Pilates exercise group participated in 1 hour Pilates exercise 3 times per week for a total of 10 weeks. Each of the participants had an X-ray and performed gait 5 times before and after the exercise treatment. The participants kinetic and kinematic data were gathered using an eight Vicon Motion camera system and two force platforms.RESULTS For the Pilates group gait their ma...

Emergency Radiology, 2021

Objective To investigate the incidence of thromboembolic events, specifically pulmonary embolism ... more Objective To investigate the incidence of thromboembolic events, specifically pulmonary embolism (PE), deep vein thrombosis (DVT), and cerebrovascular accidents (CVA), in patients who tested positive for COVID-19 through RT-PCR in a regional healthcare system in Connecticut. Materials and methods All CT angiogram (CTA) and venous duplex extremity ultrasound (US) examinations performed on 192 consecutively documented cases of COVID-19 were retrospectively reviewed at a multi-centered healthcare system. Clinical characteristics and patient outcomes were evaluated and compared between two groups based on the presence or absence of acute thromboembolic events. Results Of the 16,264 patients tested for COVID-19, 3727 (23%) were positive. Out of those, 192 patients underwent 245 vascular imaging studies including chest CTA (86), venous duplex ultrasound (134), and CTA head and neck (25). Among those who underwent imaging, 49 (26%) demonstrated acute thromboembolic events which included 13/86 (15%) with PE, 34/134 (25%) with DVT, and 6/25 (24%) with CVA. One patient had positive results on all 3 examinations, and 2 patients had positive results on both chest CTA and venous duplex US. Males were more likely to have a thromboembolic event than females (33/103 (34%) vs. 14/89 (16%), p = 0.009). No significant difference was observed with respect to age, cardiopulmonary comorbidities, malignancy history, diabetes, or dialysis. Conclusion Approximately 26% of COVID-19 patients with positive testing who underwent vascular imaging with CTA or venous duplex ultrasound had thromboembolic events including PE, DVT, and CVA. This indicates that COVID-19 patients are at increased risk for thromboembolic complications.

Technology and Health Care, 2020

OBJECTIVE: This study aims to compare and analyze the difference of impact force attenuation acco... more OBJECTIVE: This study aims to compare and analyze the difference of impact force attenuation according to size and impact location on a Taekwondo body protector. METHODS: Body protectors sized 1 to 5, were impact tested by equipment based on the specifications in the European standard manual (EN 13277-1, 3). The impactor release heights were set to match impact energies of 3 and 15 J. The impactor was made from a 2.5 kg cylindrically cut piece of aluminum. Each body protector was impacted 10 times at the two impact energies and two locations. The differences in performance for each body protector size were compared using a two-way analysis of variance with a significance level of p< 005. The effect sizes were investigated using a partial eta squared value (η2). RESULTS: The significant mean differences between the body protector size and impact area (p< 005) and the average impact time of impact strengths 3 and 15 J were 0.0017 and 0.0012 s, respectively In addition, when an i...

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2019

The requirement to measure the number and severity of head impacts in sports has led to the devel... more The requirement to measure the number and severity of head impacts in sports has led to the development of many wearable sensors. The objective of this study was to determine the reliability and accuracy of a wearable head impact sensor: xPatch, X2Biosystems, Inc. The skin-mounted sensor, xPatch, was fixed onto a Hybrid III headform and dropped using an impact test rig. A total of 400 impacts were performed, ranging from 20g to 200g linear acceleration, and impact velocities of 1.2-3.9 m/s. During each impact, the peak linear acceleration, angular velocity and angular acceleration were recorded and compared to the reference calibrated data. Impacts were also recorded using a high-speed video camera. The results show that the linear acceleration recorded by the xPatch during frontal and side impacts had errors of up to 24% when compared to the referenced data. The angular velocity and angular acceleration had substantially larger errors of up to 47.5% and 57%, respectively. The location of the impact had a significant effect on the results: if the impact was to the side of the head, the device on that side may have an error of up to 71%, thus highlighting the importance of device location. All impacts were recorded using two separate xPatches and, in certain cases, the difference in angular velocity between the devices was 43%. In conclusion, the xPatch can be useful for identifying impacts and recording linear accelerations during front and side impacts, but the rotational velocity and acceleration data need to be interpreted with caution.