• Journal of Korean Physical Therapy Science
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• v.26 no.3
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• pp.70-75
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• 2019

Purpose: The purpose of this study was to investigate the changes of static and dynamic balance control ability according to the stability of shoes in elderly woman and female university student. Design: Cross-sectional study. Methods: Six elderly women and seven female university students were recruited for this study. The subject's static and dynamic balance were evaluated while wearing two different types of shoes (comfortable running shoe and masai walking shoe). The BT4 system was used to measure the static (postural sway area and velocity) and dynamic balance (limit of stability on forward, backward and left and right side). The measurement of static and dynamic balance control ability was performed in standing posture wearing comfortable running shoes and masai walking shoes. Results: In the static balance control ability, both female university students and elderly women showed significant increase in postural sway area and velocity when wearing unstable shoes (p<0.05) In addition, in the dynamic balance control ability, both female university students and elderly women showed significant decrease in limit of stability on forward and backward when wearing unstable shoes (p<0.05). Conclusion: In selecting shoes for the elderly, the stability of shoe should be considered for prevention of falls.

• Advances in concrete construction
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• v.16 no.6
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• pp.291-302
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• 2023

As the first part of the body that strikes the ground during running, sports shoes are especially important for improving performance and reducing injuries. The use of new nanotechnology materials in the shoe's sole that can affect the movement angle of the foot and the ground reaction forces during running has not been reported yet. It is important to consider the material of the sole of the shoe since it determines the long-term performance of sports shoes, including their comfort while walking, running, and jumping. Running performance can be improved by polymer foam that provides good support with low energy dissipation (low energy dissipation). Running shoes have a midsole made of ethylene propylene copolymer (EPP) foam. The mechanical properties of EPP foam are, however, low. To improve the mechanical performance of EPP, conventional mineral fillers are commonly used, but these fillers sacrifice energy return. In this study, to improve the magnificence of physical education training with nanotechnology, carbon nanotubes (CNTs) derived from recycled plastics were prepared by catalytic chemical vapor deposition and used as nucleating and reinforcing agents. As a result of the results, the physical, mechanical, and dynamic response properties of EPP foam combined with CNT and zinc oxide nanoparticles were significantly improved. When CNT was added to the nanocomposites with a weight percentage of less than 0.5 wt%, the wear resistance, physical properties, dynamic stiffness, compressive strength, and rebound properties of EPP foams were significantly improved.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.153-168
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• 2005

The purposes of this study were to determine the influence of midsole hardness and sole thickness of sports shoes on ball flex angle and position with increment of running velocity. The subjects employed for this study were 10 college students who did not have lower extremity injuries for the last one year and whose running pattern was rearfoot striker of normal foot. The shoes used in this study had 3 different midsole hardness of shore A 40, shore A 50, shore A 60 and 3 different sole thickness of 17cm, 19cm, 21cm. The subjects were asked to run at 3 different speed of 2.0m/sec, 3.5m/sec, 5.0m/sec and their motions were videotaped with 4 S-VHS video cameras and 2 high speed video cameras and simultaneously measured with a force platform. The following results were obtained after analysing and comparing the variables. Minimum angle of each ball flex position were increased with the increment of running velocity and shoe sole thickness(P<0.05), but mid-sole hardness did not affect minimum ball flex angle. The position which minimum angle was shown as smallest was 'D'. Midsole hardness and sole thickness did not affect time to each ball flex minimum angle, total angular displacement of ball flex angle, and total angular displacement of torsion angle(P<0.05). The position which minimum angle was appeared to be earliest was similar at walking velocity, and E and F of midfoot region at running velocity. Total angular displacement of ball flex position tended to increase as shifted to heel. It was found that running velocity had effects on ball flex angle variables, but shoe sole thickness partially affected. It would be considered that running velocity made differences between analysis variables at walking and running when designing shoes. Also, it was regarded that shoes would be developed at separated region, because ball flex angle and position was shown to be different at toe and heel region. It is necessary that midsole hardness and thickness required to functional shoes be analyzed in the further study.

• Fashion & Textile Research Journal
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• v.23 no.3
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• pp.390-405
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• 2021

Gait analysis trackers have been developed to monitor daily gait patterns to improve users' running performance and reduce the risk of injuries. A variety of gait analysis trackers are available on the market(e.g., foot pods, insoles). Depending on the type of gait analysis tracker, users' discomfort or satisfaction as well as required properties may differ. Hence, the purpose of this study was to compare and analyze user experience of three different types of commercial shoe-mounted gait analysis trackers and their mobile applications in a laboratory environment using questionnaires based on actual experiences of each product. Ten males and ten females who regularly enjoy walking and running exercises participated in the experiment. After the participants set up the tracker and application themselves without support from researchers, ten to thirty minutes' exercise was permitted on each product. Following this, the participants answered questionnaires containing evaluation variables on the device and mobile application, as well as satisfaction, intention to use, recommendation, and purchase. In addition, they were asked questions about the attractive features and shortcomings of each device and application. The results showed that the PRO-SPECS^® smart insole was preferred over the others for ease of use, perceived durability, psychological burden of the design, and usefulness of the information provided by the application. Along with the results of questionnaire, this study also discussed strategies and recommendations for future product design and development.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.197-204
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• 2020

Objective: The purpose of this study was to investigate the effect of increased running speed on the magnitude of impact shock attenuation in high frequency (9~20 Hz) at support phase on the treadmill running. Method: Twenty-four healthy male heel-toe runners participated in this study. Average age, height, mass, and preference running speed were 23.43±3.78 years, 176.44±3.38 cm, 71.05±9.04 kg, and 3.0±0.5 m/s, respectively. Three triaxial accelerometer (Noraxon, USA) were mounted to the tuberosity of tibia, PSIS (postero-superior iliac spine), and forehead to collect acceleration signals, respectively. Accelerations were collected for 20 strides at 1,000 Hz during treadmill (Bertec, USA) running at speed of 2.5, 3.0, 3.5, and 4.0 m/s. Power Spectrum Density (PSD) of three acceleration signals was calculated to use in transfer function describing the gain and attenuation of impact shock between the tibia and PSIS, and forehead. One-way ANOVA were performed to compare magnitude of shock attenuation between and within running speeds. The alpha level for all statistical tests was .05. Results: No significant differences resulted for magnitude of the vertical and resultant impact shock attenuation between the tibia and PSIS, and forehead between running speeds. However, significant differences within running speed were found in magnitude of the vertical shock attenuation between tibia and PSIS, tibia and forehead at speed of 2.5, 3.0 m/s, respectively. Conclusion: In conclusion, it might be conjectured that muscles covering the knee and ankle joints and shoe's heel pad need to strengthen to keep the lower extremities from injuries by impact shock at relatively fast running speed that faster than preferred running speed.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.117-122
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• 1999

Track rubber parts has heat built-up as long as dynamic loading is applied from running tracked vehicles. Durability is required for rubber part to sustain the heat accumulation and heat exchange between rubber-metal assembly and environmental air and ground. For this research, the track assembly was divided into four parts i.e., bottom track shoe, upper track pad, pin busing and metal structure. Three rubber parts and metal structure were modelled and analyzed with MARC package program to obtain time-temperature data which was induced form mechanical work of tracked vehicles. heat accumulation data was obtained from special experiments under the room temperature of 25$^{\circ}C\;and\;35^{\circ}C$ to simulate the actual environmental conditions. From this research, it is cleared that the environmental temperature does not affect to the heat accumulation speed in rubber parts. Also, the heat built-up mechanism was clarified from the thermo-mechanical work based on numerical analysis and experiments.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.1-8
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• 2006

The purpose of this study was to evaluate normalized jerk according to shoes, slope, and velocity during walking. Eleven different test subjects used three different types of shoes (running shoes, mountain climbing boots, and elevated forefoot walking shoes) at various walking speeds(1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2, 2.11, 2.33m/sec) and gradients(0, 3, 6, 10 degrees) on a treadmill. Since there were concerns about using the elevated forefoot shoes on an incline, these shoes were not used on a gradient. Motion Analysis (Motion Analysis Corp. Santa Rosa, CA USA) was conducted with four Falcon high speed digital motion capture cameras. Utilizing the maximum smoothness theory, it was hypothesized that there would be differences in jerk according to shoe type, velocity, and slope. Furthermore, it was assumed that running shoes would have the lowest values for normalized jerk because subjects were most accustomed to wearing these shoes. The results demonstrated that elevated forefoot walking shoes had lowest value for normalized jerk at heel. In contrast, elevated forefoot walking shoes had greater normalized jerk at the center of mass at most walking speeds. For most gradients and walking speeds, hiking boots had smaller medio-lateral directional normalized jerk at ankle than running shoes. These results alluded to an inverse ratio for jerk at the heel and at the COM for all types of shoes. Furthermore, as velocity increased, medio-lateral jerk was reduced for all gradients in both hiking boots and running shoes. Due to the fragility of the ankle joint, elevated forefoot walking shoes could be recommended for walking on flat surfaces because they minimize instability at the heel. Although the elevated forefoot walking shoes have the highest levels of jerk at the COM, the structure of the pelvis and spine allows for greater compensatory movement than the ankle. This movement at the COM might even have a beneficial effect of activating the muscles in the back and abdomen more than other shoes. On inclines hiking boots would be recommended over running shoes because hiking boots demonstrated more medio-lateral stability on a gradient than running shoes. These results also demonstrate the usefulness of normalized jerk theory in analyzing the relationship between the body and shoes, walking velocity, and movement up a slope.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.103-111
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• 2015

Objective : The purpose of this study was to evaluate the effect for running shoes with resilience of midsole on biomechanical properties. Methods : 10 healthy males who had no history of injury in the lower extremity with an average age of 26.5 year(SD=1.84), height of 172.22 cm(SD=4.44) and weight of 67.51 kg(SD=6.17) participated in this study. All subjects ran on the treadmill wearing three different running shoes. Foot pressure data was collected using Pedar-X system(Novel Gmbh, Germany) operating at 100 Hz. Surface EMG signals for biceps femoris, rectus femoris, vastus lateralis, medial lateralis, tibialis anterior, medial gastrocnemius, soleus and peroneus longus were acquired at 1000 Hz using Bignoli 8 System(Delsys Inc., USA). To normalize the difference of the magnitude of muscle contractions, it was expressed as a percentage relative to the maximum voluntary contraction (MVC). The impact resilience of the midsole data was collected using Fastcam SA5 system(Photron Inc., USA). Collected data was analyzed using One-way ANOVA in order to investigate the effects of each running shoes. Results : TPU midsole was significantly wider in contact area than EVA, TPE midsole in midfoot and higher in EMG activity than EVA midsole at biceps femoris. TPE midsole was significantly wider in contact area than EVA midsole in rearfoot and higher in peak pressure than EVA midsole in forefoot. EVA midsole was significantly higher in EMG activity than TPU midsole at tibia anterior. In medial resilience of midsoles, TPE midsole was significantly higher than EVA, TPU midsole. Conclusion : TPU midsole can reduce the load on the midfoot effectively and activate tibialis anterior, biceps femoris to give help to running.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.369-377
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• 2009

The purpose of this study was to determine the relationship between different soccer cleat designs and knee joint moments. Twelve physically active males (mean(SD): age: 26.4(6.2)yrs; height: 176.4(4.1)cm; mass: 74.0 (7.4)kg) were recruited Kinematic and force plate data were collected for all subjects during normal running and a $45^{\circ}$ cutting maneuver, called a v-cut. Both motions were performed at $4.0{\pm}0.2\;m/s$ on infilled artificial turf with three pairs of soccer cleats of different sole plate designs, and one pair of neutral running shoes. Inverse dynamics were used to calculate three dimensional knee joint moments, with repeated measures ANOVA and post hoc paired Student's t-test used to determine significance between shoe conditions. Significant differences were found in the extension moments of the knee for running trials, and for external rotation and adduction moments in the v-cutting trials. Knee moments were greater in v-cut than running, and the traditional soccer cleats (Copa Mondial and World Cup) tended to result in greater knee moments than the Nova runner or TRX soccer cleat. Cleat design was found to influence 3-dimensional knee moments in a v-cut maneuver. In the translational traction test, there were significant differences between all conditions. In the rotational traction test, friction with soccer shoes were greater than friction with running shoes. However, no differences were found between soccer shoes. Higher moments may lead to increased loads and stresses on knee joint structures, and thus, greater injury rates.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.89-97
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• 2008

The purpose of this study was to analyze the foot-pressure distribution of Tennis Shoes for assessing their functionality. 10 university male students (shoe size: 265mm) who had no history of injury in the lower extremity and a normal gait pattern participated in this study. Four types of tennis shoes, most popular in Korea (A, B, C & D company), were selected and tested. Using the PEDAR-X system and PEDAR-X insoles, 4 different motion stages were analyzed for the foot-pressure distribution: (a) straight running; (b) c-cut($45^{\circ}$ left turn running; (c) forehand stroke; and (d) backhand stroke. Results revealed that in all stages, there were no statistically significant differences among the types of shoes; however, descriptive statistics indicated that functionality of shoe types was somewhat different depending on the type of stages. The order in functionality found was C>A>B>D.