• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.167-174
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• 2016

Objective: The purpose of this study was to determine the interrelationship between ranges of motion of the knee and ankle joints on the sagittal plane and the attenuation magnitude of impact shock at high frequency (9~20 Hz) in the support phase during downhill running. Method: Fifteen male heel-toe runners with no history of lower extremity injuries were recruited for this study (age, $25.07{\pm}5.35years$; height, $175.4{\pm}4.6cm$; mass, $75.8{\pm}.70kg$). Two uniaxial accelerometers were mounted to the tuberosity of tibia and sacrum, respectively, to measure acceleration signals. The participants were asked to run at their preferred running speed on a treadmill set at $0^{\circ}$, $7^{\circ}$, and $15^{\circ}$ downhill. Six optical cameras were placed around the treadmill to capture the coordinates of the joints of the lower extremities. The power spectrum densities of the two acceleration signals were analyzed and used in the transfer function describing the gain and attenuation of impact shock between the tibia and the sacrum. Angles of the knee and ankle joints on the sagittal plane and their angle ranges were calculated. The Pearson correlation coefficient was used to test the relationship between two variables, the magnitude of impact shock, and the range of joint angle under three downhill conditions. The alpha level was set at .05. Results: Close correlations were observed between the knee joint range of motion and the attenuation magnitude of impact shock regardless of running slopes (p<.05), and positive correlations were found between the ranges of motion of the knee and ankle joints and the attenuation magnitude of impact shock in $15^{\circ}$ downhill running (p<.05). Conclusion: In conclusion, increased knee flexion might be required to attenuate impact shock during downhill and level running through change in stride or cadence while maintaining stability, and strong and flexible ankle joints are also needed in steeper downhill running.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.69-81
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• 2005

In this study using two-dimensional system of the analysis of image, when normal males in their twenties who have normal foot and step with heel first are walking and running, they who are wearing running shoes or barefoot are testing and comparing the exchange factors of heel control. There are following results of this test by verifying them with T-Test. 1) When they are running, there are two big different gap which is $6.05^{\circ}$ between barefoot and wearing the running shoes. The former is $174.79^{\circ}{\pm}6.31$ and the latter is $180.84^{\circ}{\pm}4.69$. But it is not statistically significant. The angle of first step with heel is $100.42^{\circ}{\pm}3.95$ with barefoot and $93.97^{\circ}{\pm}094$ with wearing the running shoes. In this case, it is statistically significant(p<.01) 2) When they are running, the angle of the Achilles' tendon has different gap which is $5.24^{\circ}$ between barefoot and wearing the running shoes. The former is $179.70^{\circ}{\pm}4.23$ and the latter is $184.94^{\circ}{\pm}4.09$. It is not statistically significant. The angle of minimal step with heel is $96.30^{\circ}{\pm}3.07$ with barefoot and $90.84^{\circ}{\pm}0.44$ with wearing the running shoes. In this case, it is statistically significant(p<.01). 3) In the angle of the Achilles' tendon and the angle of first step with heel, when they are walking, the angle of the Achilles' tendon has different gap which is $1.81^{\circ}$ between barefoot and wearing the running shoes. The former is $6.39^{\circ}{\pm}0.83$ and the latter is $8.20^{\circ}{\pm}1.85$. It is not statistically significant. The angle of first step with heel is $2.32^{\circ}{\pm}0.51$ with barefoot and $3.22^{\circ}{\pm}1.44$ with wearing the running shoes. It is not statistically significant. 4) In the angle of the take-off of Achilles' tendon, when they are walking, the angle of the take-off of Achilles' tendon has different gap which is $3.88^{\circ}$ between barefoot and wearing the running shoes. The former is $177.62^{\circ}{\pm}8.78$ and the latter is $173.74^{\circ}{\pm}16.31$. It is statistically significant(p<.05). Therefore, they are running, the angle of the take-off of Achilles' tendon is $178.37^{\circ}{\pm}19.28$ with barefoot and $171.26^{\circ}{\pm}12.18$ with wearing the running shoes. It is statistically significant(p<.05).

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1023-1029
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• 2013

Water running animals such as basilisk lizards have an advantage of high-speed movement and high power efficiency on water; so researchers in robotic fields have been interested in the water running locomotion. This paper presents prototype-design and experimental study on the fourand six-legged water running robot. Based on the previously proposed quadruped water running robot, we assemble a hexapedal water running robot. The legs of the water running robot are designed based on four-bar parallel link for repeated motion along to pre-defined path. Stability performance of the quadruped and hexapedal water running robot are investigated by experiments on rolling criterion. As a result, hexapedal robot performs better stability than quadruped robot. Based on the hexapedal robot design, we are planning to optimize the position of legs and operating frequency.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.290-296
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• 2021

Objective: The purpose of this research is to examine the effects of three types of different running shoes with different properties on impact variables (PVRGF and VLR) and the lower extremity joint's dynamic stability variables (LyEs of DPA, IEA, FEA, DPAV, IEAV, and FEAV) during running. Method: The participants in this research were 12 males (Age: 22.0 ± 3.3 years, Height: 177.2 ± 4.1 cm, Weight: 74.3 ± 9.6 kg). One type of N company's running shoes and two types (FA, FB) of F company's running shoes were used. As for the properties of the running shoes, thickness (mm), dwell time (ms), peak acceleration (m/s2), and energy return (%) were measured. The motions running at 3.5 m/s on a treadmill (Instrumented treadmill, Bertec, USA) wearing each type of running shoes were analyzed. Results: Although the VLR of the thick running shoes (FB) was smaller than that of the other running shoes (N, FA), the LyEs of PVGRF and DPA were larger (p<.05). Even though the running shoes' dwell time (i.e., impact absorption time) and peak acceleration showed a positive correlation with the LyEs of DPAV, IEAV, and FEAV, the energy return showed a negative correlation (p<.05). Conclusion: Our results indicated that the running shoes with excellent impact absorption function are predicted to be suitable for running beginners who need to reduce the burden of the lower extremity joint during running. The running shoes with excellent energy return are expected to be suitable for mid-and long-distance running elite athletes or marathoners to whom stability and consistency are essential during running.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.241-248
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• 2021

Objective: The purpose of this study was to investigate the difference in muscle strength, kinematics, and kinetics between injured and non-injured sides of the leg after Achilles Tendon Rupture surgery during walking and running. Method: The subjects (n=11; age = 30.63 ± 5.69 yrs; height = 172.00 ± 4.47 cm; mass = 77.00 ± 11.34 kg; time lapse from surgery = 29.81 ± 10.27 months) who experienced Achilles Tendon Rupture (ATR) surgery participated in this study. The walking and running trials were collected using infrared cameras (Oqus 300, Qualisys, Sweden, 100 Hz) on instrumented treadmill (Bertec, U.S.A., 1,000 Hz) and analyzed by using QTM (Qualisys Track Manager Ver. 2.15; Qualisys, U.S.A). The measured data were processed using Visual 3D (C-motion Inc., U.S.A.). The cutoff frequencies were set as 6 Hz and 12 Hz for walking and running kinematics respectively, while 100 Hz was used for force plate data. Results: In ATR group, muscle strength there were no difference between affected and unaffected sides (p> .05). In kinematic analysis, subjects showed greater ROM of knee joint flexion-extension in affected side compared to that of unaffected side during walking while smaller ROM of ankle dorsi-plantar and peak knee flexion were observed during running (p< .05). In kinetic analysis, subjects showed lower knee extension moment (running at 2.2 m/s) and positive ankle plantar-flexion power (running at 2.2 m/s, 3.3 m/s) in affected side compared to that of unaffected side (p< .05). This lower positive ankle joint power during a propulsive phase of running is related to slower ankle joint velocity in affected side of the subjects (p< .05). Conclusion: This study aimed to investigate the functional evaluation of the individuals after Achilles tendon rupture surgery through biomechanical analysis during walking and running trials. Based on the findings, greater reduction in dynamic joint function (i.e. lower positive ankle joint power) was found in the affected side of the leg compared to the unaffected side during running while there were no meaningful differences in ankle muscle strength and walking biomechanics. Therefore, before returning to daily life and sports activities, biomechanical analysis using more dynamic movements such as running and jumping trials followed by current clinical evaluations would be helpful in preventing Achilles tendon re-rupture or secondary injury.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.160-167
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• 2020

This study analyzes the effects of changes in running velocity and slope on the biomechanical factors of the lower limb joints. For this purpose, 15 adult males in their 20s ran according to changes in running speed (2.7, 3.3 m/s) and slope ( -9°, -6°, 0°, 6°, 9°) on the treadmill, and their running characteristics (stride length, stride frequency). The range of motion of the lower limb joint and the vertical ground reaction force were greater in UR (p <.05), and the moment of the lower limb joint, braking force, thrust and load factor was large in DR (p <.05). In joint power, the ankle joint was greater in DR, and hip joint was greater in the UR (p <.05). These results show that the injuries of the ankle joint will be greater than other cases when running DR at a speed of 3.3 m/s.

• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.164-174
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• 2023

Objective: The aim of this study was to quantitatively analyze the impact characteristics of the lower extremity on strike pattern during running. Method: 19 young subjects (age: 26.53 ± 5.24 yrs., height: 174.89 ± 4.75 cm, weight: 70.97 ± 5.97 kg) participated in this study. All subjects performed treadmill running with fore-foot strike (FFS), mid-foot strike (MFS), and rear-foot strike (RFS) to analyze the impact characteristics in the lower extremity. Impact variables were analyzed including vertical ground reaction force, lower extremity joint moments, impact acceleration, and impact shock. Accelerometers for measuring impact acceleration and impact shock were attached to the heel, distal tibia, proximal tibia, and 50% point of the femur. Results: The peak vertical force and loading rate in passive portion were significantly higher in MFS and FFS compared to FFS. The peak plantarflexion moment at the ankle joint was significantly higher in the FFS compared to the MFS and RFS, while the peak extension moment at the knee joint was significantly higher in the RFS compared to the MFS and FFS. The resultant impact acceleration was significantly higher in FFS and MFS than in RFS at the foot and distal tibia, and MFS was significantly higher than FFS at the proximal tibia. In impact shock, FFS and MFS were significantly higher than RFS at the foot, distal tibia, and proximal tibia. Conclusion: Running with 3 strike patterns (FFS, MFS, and RFS) show different impact characteristics which may lead to an increased risk of running-related injuries (RRI). However, through the results of this study, it is possible to understand the characteristics of impact on strike patterns, and to explore preventive measures for injuries. To reduce the incidence of RRI, it is crucial to first identify one's strike pattern and then seek appropriate alternatives (such as reducing impact force and strengthening relevant muscles) on that strike pattern.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.1
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• pp.31-35
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• 2001

This study is object to structural analysis of running machine frame. The finite element model was developed to compute the stress. strain and natural frequency for running machine frame. The FEM code was used for this analysis. In other to structural analysis of running machine frame, many variables such as load condition, boundary condition and weight condition were considered.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.9-18
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• 2006

These studies show that I applied to functional insole (a specific S company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average $2.0{\pm}0.24$ meter per second by motion analysis, ground reaction force and electromyography that used to specific A company. First of all, Motion analysis was caused by Achilles tendon angle, Angle of the lower leg, Angle of the knee, Initial sole angle and Barefoot angle. Second, Contact time, Vertical impact force peak timing, Vertical active force and Active force timing, and Maximum loading rate under impulse of first 20 percent and Value of total impulse caused Ground reaction force. Third. The tendon fo Quadriceps femoris, Biceps femoris, Tibialis anterior and gastronemius medials caused. electromyography. 1. Ground reaction force also showed that statically approximates other results from impact peak timing (p.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). 2 Electromyography showed that averagely was distinguished from other factors, and did not show about that. Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.

• Journal of the Korean Society for Railway
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• v.4 no.3
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• pp.116-122
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• 2001

As freight traffic becomes heavier, the high speed of existing freight cars is essential, instead of the construction of a new railway. The high speed can be achieved by the modifications of freight bogie design. In this paper, an analytical model of freight bogie is developed to decide the critical speed. The dynamic responses of the analytical model are compared with the experimental data from a running test of freight bogie and showed good agreements between them. The analytical model is used to find the design of freight bogie. The parameter studies show that the reduction of wheelset mass ratio and the increase of the axle distance of freight bogie can increase the critical speed, but the primary lateral stiffness has little effects on the critical speed. And this study also shows that smaller wheel conicity deteriorates the running safety of freight car, which means that the overhauling of the wheel of freight bogie should be done regularly.