• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.121-134
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• 2006

The purpose of this study was to analyze the effect of different types of rehabilitation training program on the kinetic and kinematic parameters during sit-to-stand movement(STS) in chronic stroke patients. Two groups of hemiparetic patients, experimental and control, participated in the study. The experimental group participated in a 10-week training program (three sessions/wk, $1{\sim}1.5\;hr/session$) consisting of a warm-up, aerobic exercises, lower extremity strengthening. and a cool-down. The control group participated in an aerobic exercise. Three dimensional kinematic analysis and force platform; were used to analyze the duration of STS, lower extremity angle, and weight bearing ability. The experimental group which had more strength of lower extremity displayed decrease in duration of STS. However, the control group showed increases in duration during sit-to-stand movement. The control group flexed their trunk more than the group did Therefore, it took more time to extend their trunk during STS. The duration in sit-to-stand was affected by the strength of lower extremity and the angle of trunk movement. The angles of ankle and knee joint had an influenced on duration of STS. The post experimental group performed with their feet near the front leg of the chair during sit-to-stand, therefore the duration was decreased. The repetitive sit-to-stand movements as a resistance exercise was effective to hemiparetic patients in learning mechanism of sit-to-stand. The control group showed decreased differences in the vertical ground reaction forces between paretic and non-paretic limbs. Their training program included strengthening exercise that may help improving weight bearing ability. The control group showed increases in the center of pressure in the anteroposterior and mediolateral displacement. This means that the stability of movement was low in the control group. Their training program which combined aerobic and strengthening exercises that are more effective to improve the stability of movement.

• The Journal of Korea Robotics Society
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• v.17 no.3
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• pp.303-307
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• 2022

This paper proposes a method that can generate a smooth trajectory from the discontinuous trajectory in kinematic, dynamic, and task-space trajectory constraints. The problem is defined as the minimization of kinetic energy, and then the simulation is performed by using the MATLAB. Kinematic and inverse kinematic equations are derived for the simulation of the 6-DOF robotic arm. The simulation results showed that the trajectory of each joint is generated while satisfying the constraints without any discontinuity. There are small errors in the Cartesian trajectory, but unnecessary deceleration and acceleration can be eliminated. In addition, it is possible to quickly switch between the robotic tasks by applying the proposed method.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.15 no.2
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• pp.33-41
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• 2020

Objectives The purpose of this report was to study the circulation of meridian WiGi, YoungGi, from the viewpoint of manual medicine. Methods First, the Korean Medical approach analyzes documents about the circulation of meridian WiGi, YoungGi, and the biomechanical approach is to analyze documents about kinetic force and kinematic movement. The third inherent energy approach is to analyze documents about craniosacral rhythm and visceral motility. Finally, it is to study the correlation between the circulation of meridian WiGi, YoungGi, and the viewpoint of biomechanics force and movement, the inherent energy of manual medicine. Results Meridian WiGi is fast, powerful, and changeful. It circulates through the head and extremities in the daytime and visceral organs at night. The deviation pelvis and distorted thoracic cage create kinetic force and kinematic movement. Meridian YoungGi is very small and soft energy and circulates meridians and visceral organs permanently. Craniosacral rhythm and visceral motility radiate continuously from cranial and visceral organs to the whole body. Conclusions Circulation of meridian WiGi is closely related to the biomechanical approach. In addition, circulation of meridian YoungGi is closely related to the inherent energy approach.

• Journal of the Ergonomics Society of Korea
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• v.25 no.2
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• pp.33-42
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• 2006

It is important to analyze the characteristics of normal gait in clinical and biomechanical aspects. Although gait characteristics can be varied by anthropometric, racial and cultural factors, normal gait studies have been performed mostly for Western people. The present study conducted a gait analysis for Korean young adults and compared the gait characteristics with those of Western people for the establishment of Korean normal gait data. A total of thirty-two adults in twenties(20 males and 12 females) were participated in the gait experiment and their spatio-temporal and kinematic/kinetic gait characteristics were analyzed. The comparison of the gait characteristics between Korean and Western people, revealed that the stride length and walking speed of Korean were significantly smaller than those of Western people by 0.1~0.3m and 0.15~0.40m/s respectively. And the knee abduction moment of Korean was larger than that of Western people, while the other moments(such as hip flexion/extension moments, abduction/adduction moments, and knee flexion/extension moments) were smaller than those of Western people. The ranges of joint angles between the gait studies were largely different with each other, but most of motion patterns and excursions were similar.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.365-372
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• 2010

The purpose of this study were to analyze the changes in kinematic and kinetic parameters and to find biomechanical benefits of Nordic Walking and normal gait performed under the same velocity. Nine participants(age: $26.73{\pm}3.28$ year, height: $182.45{\pm}4.62\;cm$, weight: $76.59{\pm}6.84\;kg$) was chosen. The velocity of gait was set by 5.75 km/h which was made by a Nordic Walking professional. The data were collected by using VICON with 8 cameras to analyze kinematic variables with 200 Hz and force platform to analyze kinetic variables with 2000 Hz. The results of this study were as follows. First, when compared with Normal gait, Nordic Walking group showed decreased Plantarflexion angle and ROM. Second, Nordic Walking group showed decreased knee flexion angle and ROM. Third, Nordic Walking group showed increased hip joint movement. Fourth, Nordic Walking group showed higher active GRF but decreased loading rate from delayed Peak Vertical GRF time and increased impulse. Fifth, Nordic Walking group showed longer ground contact time. Through this study, we found that Nordic Walking showed higher stability and efficiency during gait than normal gait and that Nordic Walking may help people who have walking difficulties.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.9-17
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• 2024

Objective: The purpose of this study is to apply 8-week velocity-based training to domestic professional athletes and the kinematic and kinetic analysis of the 1-RM improvement of back squat and power clean, which can represent strength-power ability, to verify the effectiveness of velocity-based training in Korea and to establish a basic basis. Method: The subjects who participated in this study were 10 professional athletes from K University (age: 21.40 ± 0.97 yrs., height: 179.90 ± 3.54 cm., body mass: 71.298 ± 2.98 kg). All subjects performed back squat and power clean 1-RM before and after 8-weeks of velocity-based training. A 3-dimensional motion analysis with 8 infrared cameras and 4 channels of EMG was performed in this study. A paired t-test was used for statistical verification. The significant level was set at α=.05. Results: Both Back squat and Power Clean 1-RM showed statistically significant increases (p<.05). In the case of back squat, there was no statistically significant difference in both kinematic and kinetic variables (p>.05). In the case of Power Clean, only the quadriceps of Phase 1 showed a statistically significant decrease (p<.05). Conclusion: Domestic professional athletes can improve their strength-power ability through velocity-based training, and such training for at least 8-weeks is considered a way to improve their performance.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.259-274
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• 2005

The purpose of this study was to compare the kinematic and kinetic parameters of lower extremity joints between novice and experienced sports aerobic dancers during two heights of depth jumps. Four male dancers were participated in this study and they performed 40cm and 60cm height depth jump three times, respectively. Four ProReflex MCU cameras (100frame/sec) and a Kistler force plate (1000Hz) were used for data collection. The results indicated that the duration of contact phase of experienced group was shorter than that of novice group regardless of jump height. For minimum angle of hip, knee, and ankle joints, the novice group had tendency to decrease the angle but the experienced group had increased the joint angle with jump height. There was no difference of total ground reaction force between the groups but the reaction force had tendency to increase with jump height. Thus, this study implied that repetition of jump and landing may induce joint related injury and further study such as. EMG analysis of lower extremity can be needed to verify the relationship between injury and ground reaction force.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.105-108
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• 2011

The purpose of the present study was to analyze the lower stiffness over the difference between soft and stiff landings during hopping. Five male subjects performed hopping on two legs at 2.5 Hz. During the experiments, 3D motion capture system was used to obtain the kinematic data and two force plates were synchronized to calculate the kinetic data. We determined lower extremity stiffness of the knee and ankle from kinetic and kinematic data. Leg stiffness was approximately 1.2-times significantly higher in stiff landing than in soft landing_ There was no significant difference in knee joint stiffness between soft and stiff landings. Ankle joint stiffness was approximately 1.34-times significantly higher in stiff landing than in soft landing. These results suggest that humans adjust lower extremity stiffness over the comparison of two different landing methods we evaluated.

• Korean Journal of Applied Biomechanics
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• v.31 no.2
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• pp.113-118
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• 2021

Objective: The purpose of this study was to investigate differences of landing strategy between people with or without chronic ankle instability (CAI) during double-leg drop landing. Method: 34 male adults participated in this study (CAI = 16, Normal = 18). Participants performed double-leg drop landing task on a 30 cm height and 20 cm horizontal distance away from the force plate. Lower Extremities Kinetic and Kinematic data were obtained using 8 motion capture cameras and 2 force plates and loading rate was calculated. Independent samples t-test were used to identify differences between groups. Results: Compared with normal group, CAI group exhibits significantly less hip internal rotation angle (CAI = 1.52±8.12, Normal = 10.63±8.44, p = 0.003), greater knee valgus angle (CAI = -6.78±5.03, Normal = -12.38 ±6.78, p = 0.011), greater ankle eversion moment (CAI = 0.0001±0.02, Normal = -0.03±0.05, p = 0.043), greater loading Rate (CAI = 32.65±15.52, Normal = 18.43±10.87, p = 0.003) on their affected limb during maximum vertical Ground Reaction Force moment. Conclusion: Our results demonstrated that CAI group exhibits compensatory movement to avoid ankle inversion during double-leg drop landing compared with normal group. Further study about how changed kinetic and kinematic affect shock absorption ability and injury risk in participants with CAI is needed.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.99-108
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• 2017

Objective: The purpose of this study was to analyze the effects of skill level and width between feet on kinematic and kinetic variables during jump rope single under with both feet. Method: Fifteen subjects in the skilled group (age: $10.85{\pm}0.40yrs$, height: $142.13{\pm}5.41cm$, weight: $36.97{\pm}6.65kg$) and 15 subjects in the unskilled group (age: $10.85{\pm}0.40yrs$, height: $143.31{\pm}5.54cm$, weight: $40.81{\pm}10.39kg$) participated in this study. Results: Participants in the skilled group minimized the anteroposterior displacement of their center of mass by modifying the width between their feet and decreased the range of motion (ROM) of their trunk in the sagittal plane. The preferred width during the jump rope decreased by 5.61~6.11 cm (32~37%) in comparison to width during static standing. The induced width was increased by 16.44~16.67 cm (82~85%), regardless of skill level. The kinematic variables of the left and right legs of members of the unskilled group were significantly different from those of members in the skilled group regarding the ROM of the hip, knee, and ankle joint. Otherwise, the members of the skilled group were consistent in terms of the kinematic variables of the right and left legs. Conclusion: The preferred width between feet during the jump rope was found to be beneficial for maintaining dynamic stability. The unskilled group exhibited asymmetry in left and right motion within the ranges of motion of the ankle, knee, and hip joints, regardless of the width. Therefore, long-term accurate jump rope motions will contribute to an improvement in the left and right imbalances of the entire body.