• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.49-56
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• 2015

Objectives : The purpose of this study was to present quantitative data and basic references to decrease the accident risk of soccer instructors. Methods : To obtain data, we conducted an investigation on how H/Q ratio affects the dynamic stability of the lower extremity at the time of drop landing. The study targeted 13 soccer players from C University who have not had any injuries or wounds in the lower extremity joints and in any other parts of their bodies over the last 6 months. By using CMIS (USA), the players were divided into two groups according to H/Q ratios higher and lower than 69%, respectively. The subjects in each group were instructed to perform a drop landing. Results : The H/Q ratio did not affect the maximal flexion angle of the knee joints at the time of drop landing. In addition the dominant group with a relatively high H/Q ratio was observed to have increased time to reduce shock and to efficiently absorb the ground reaction force during drop landing. Also, the dominant group with a relatively high H/Q ratio utilized the strong performances of the antagonistic muscles around the hamstrings and the controlled rotatory powers of the thighs that were applied to the tibias supported by the ground. Finally, H/Q ratio, load factors, and mean and maximum EMG were significantly negatively related, whereas GRFx showed a positive relationship. In fact, these factors all affected the impact of the load from the H/Q ratio to the knee joints. Conclusion : From these findings it can be concluded that unbalanced H/Q ratio can be considered as a predictor of knee joint injury at the time of drop landing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.114-117
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• 2000

We developed a motion capture system to get angle data of human joints in walking mode. The data are used to coordinate the biped-walking robot developed in our laboratory. A pair of motion capture system is composed of three links with the ankle, knee, and pelvis joints. The system has six axes attached with potentiometers. We used an A/D converter was used to get digital data from joint angles. We filterd the data using the Butterworth 4th order digital filter, and simulated walking motion based on the data using the Matlab.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.41-49
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• 2007

This study was to investigate the kinematical analysis using ski simulator. Twelve people(six skilled, six unskilled) participated in the experiment. Each phase of motion time was slight differences between the skilled group and the unskilled group but not significant difference in statistics. In displacement of vertical on COG(Center of Gravity), left and right down motion showed significant difference between group. In velocity of horizontal on COG, both left and right down motion showed significant difference between group, and up motion of between down motion showed significant difference. In displacement of angle on ankle, knee, hip joint almost showed significant difference between group. Almost in body position was lower skilled group than unskilled group.

• PNF and Movement
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• v.11 no.1
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• pp.63-68
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• 2013

Purpose : The purpose of this study was to examine changes in spatiotemporal gait parameters(STGPs) in healthy adults before and after a immediate intervention of a Mulligan taping program(MTP). Methods : A total of 12 healthy adults(mean age, 20.82 years; age range, 19-24 years) participated in the study. performance was assessed by recording changes in the STGPs using GaitRite. comparisons of changes in the STGPs at pre-intervention and at dischange were analyzed using the Wilcox signed rank test and Mann-Whithney U test. Results : There was a significant improvement in the outcome measures of STGPs(stride length, velocity) after immediate of MTP(p<0.05). However, no significant different pre-test and post-test step width, toe angle(p>0.05). Conclusion : Participants in a MTP improves STGPs, thereby increasing the ability of healthy adults to maintain gait. MTP appears to be a safe and efficacious, noninvasive treatment modality for patients with knee joint disease.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.1-9
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• 2013

The purpose of this study was to provide information on athletes' characteristics and advantages and disadvantages by analyzing the kinematic factors having a decisive influence on competitive abilities such as release conditions in the delivery phase on major Korean javelin athletes. Two supported javelin throwers of the Korean national team participated in this study. The total average time required of the delivery phase was 0.31(${\pm}0.016$). The athletes' release angle was 33.2 to 41.7 degrees. The attack angle varied widely from -3.5 to 5.9 degrees. The Javelin heights of Subject A and B were 95.9 and 89.2%Ht. The average stride length were 180.6 and 176.7cm. The center of mass velocity of LFD and REL was relatively low in all the subjects. The average deceleration rates of center of mass velocity of Subject A and B were 57.2 and 48.9%lose. The left knee angles of Subject A and B were 160.1 and 155.5 degrees in LFD, 153.0 and 164.0 degrees in REL. The joint velocity of upper limb segments was relatively low in all the subjects. The maximum average wrist velocity of Subject A and B was 18.2 and 16.3 m/s in REL.

• 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.26 no.4
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• pp.383-390
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• 2016

Objective: Gymnastics on rings needs a high level of muscle strength with balance ability for controlling the body. A study on a new balance training program is necessary for elite gymnasts. Therefore, the purpose of this study was to investigate the effects of an 8-week pilates core-muscle training on balance ability and asymmetry index of the L-sit on the rings in male elite gymnasts. Method: Ten elite gymnasts (age: $20.6{\pm}0.7years$, height: $169.9{\pm}4.9cm$, weight: $65.4{\pm}5.6kg$, career duration: $20.6{\pm}0.7years$), who are students at K-university, participated in this study. Results: First, the range of the COM tended to decrease in the anterior-posterior direction. Second, the left hip joint angle and knee extension and ankle dorsiflexion angles significantly increased after the pilates training. Third, the ROM also increased. Fourth, the symmetry value increased in the hip angle, while the symmetry index in all joints of the ROM decreased. As a result, the pilates core-muscle training influenced the static balance ability during the L-sit on the rings. Conclusion: Accordingly, the pilates core-muscle training is suitable in enhancing the basic balance ability in gymnastics on rings.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.65-75
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• 2002

The study has a goal that produces abundant documents that needed for athletes to teach and progress skills by analyzing 3-dimensional action analysis of C-difficulties Ring jump included in body original elements among techniques constructing Rhythmic Sport Gymnastics. 1. It was the longest applied time delay that E-3 indicates 0.409${\pm}$0.017sec in each event applied time delay. 2. It was the tallest height that E-3 indicates 88.5${\pm}$1.3% in displacement of body's center. 3. It was the fastest velocity in E-2 where the velocity of left foot is 732.4${\pm}$46.1cm/sec, the velocity of right foot is 1958.4${\pm}$25.1cm/sec. 4. the lowest angle was founded at 97.8 degree in the E-3 on the trunk extension angle. 5. The lowest angle of both sides were seen at 92.8${\pm}$14.9degree and 69.2${\pm}$5.7degree in the E-3 on the each displacement of knee joint. 6. The highest angle of both sides were seen at 171.3${\pm}$6.9degree and 167.9${\pm}$8.4degree in the E-3 on the each displacement of ankle joint As a result of these studies, by jumping with ankle joint extension to accomplish the Ring jump action, it is considered to have the time of flexiblity and staying in the air which we can see in a back.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.149-163
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• 2006

The purpose of this study was to compare the lower extremity's joint and segment coupling patterns between forward and backward running in subjects who were twelve healthy males. Three-dimensional kinematic data were collected with Qualisys system while subjects ran to forward and backward. The thigh internal/external rotation and tibia internal/external rotation, thigh flexion/extension and tibia flexion/extension, tibia internal/external rotation and foot inversion/eversion, knee internal/external rotation and ankle inversion/eversion, knee flexion/extension and ankle inversion/eversion, knee flexion/extension and ankle flexion/extension, and knee flexion/extension and tibia internal/external rotation coupling patterns were determined using a vector coding technique. The comparison for each coupling between forward and backward running were conducted using a dependent, two-tailed t-test at a significant level of .05 for the mean of each of five stride regions, midstance(1l-30%), toe-off(31-50%), swing acceleration(51-70%), swing deceleration(71-90), and heel-strike(91-10%), respectively. 1. The knee flexion/extension and ankle flexion/extension coupling pattern of both foreward and backward running over the stride was converged on a complete coordination. However, the ankle flexion/extension to knee flexion/extension was relatively greater at heel-strike in backward running compared with forward running. At the swing deceleration, backward running was dominantly led by the ankle flexion/extension, but forward running done by the knee flexion/extension. 2. The knee flexion/extension and ankle inversion/eversion coupling pattern for both running was also converged on a complete coordination. At the mid-stance. the ankle movement in the frontal plane was large during forward running, but the knee movement in the sagital plane was large during backward running and vice versa at the swing deceleration. 3. The knee flexion/extension and tibia internal/external rotation coupling while forward and backward run was also centered on the angle of 45 degrees, which indicate a complete coordination. However, tibia internal/external rotation dominated the knee flexion/extension at heel strike phase in forward running and vice versa in backward running. It was diametrically opposed to the swing deceleration for each running. 4. Both running was governed by the ankle movement in the frontal plane across the stride cycle within the knee internal/external rotation and tibia internal/external rotation. The knee internal/external rotation of backward running was greater than that of forward running at the swing deceleration. 5. The tibia internal/external rotation in coupling between the tibia internal/external rotation and foot inversion/eversion was relatively great compared with the foot inversion/eversion over a stride for both running. At heel strike, the tibia internal/external rotation of backward running was shown greater than that of forward(p<.05). 6. The thigh internal/external rotation took the lead for both running in the thigh internal/external rotation and tibia internal/external rotation coupling. In comparison of phase, the thigh internal/external rotation movement at the swing acceleration phase in backward running worked greater in comparison with forward running(p<.05). However, it was greater at the swing deceleration in forward running(p<.05). 7. With the exception of the swing deceleration phase in forward running, the tibia flexion/extension surpassed the thigh flexion/extension across the stride cycle in both running. Analysis of the specific stride phases revealed the forward running had greater tibia flexion/extension movement at the heel strike than backward running(p<.05). In addition, the thigh flexion/extension and tibia flexion/extension coupling displayed almost coordination at the heel strike phase in backward running. On the other hand the thigh flexion/extension of forward running at the swing deceleration phase was greater than the tibia flexion/extension, but it was opposite from backward running. In summary, coupling which were the knee flexion/extension and ankle flexion/extension, the knee flexion/extension and ankle inversion/eversion, the knee internal/external rotation and ankle inversion/eversion, the tibia internal/external rotation and foot inversion/eversion, the thigh internal/external rotation and tibia internal/external rotation, and the thigh flexion/extension and tibia flexion/extension patterns were most similar across the strike cycle in both running, but it showed that coupling patterns in the specific stride phases were different from average point of view between two running types.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.249-256
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• 2015

Objective : The purposes of this study was to perform a kinematical analysis on age and walkway types in elderly women subjects. Method : Forty subjects participated in the experiment (A1 group - age: $67.30{\pm}1.49yrs$, height: $153.81{\pm}4.47cm$, weight: $61.80{\pm}5.24kg$, A2 group - age: $71.70{\pm}1.10yrs$, height: $152.01{\pm}2.84cm$, weight: $59.69{\pm}7.34kg$, A3 group - age: $76.80{\pm}0.98yrs$, height: $150.16{\pm}6.08cm$, weight: $57.27{\pm}6.42kg$, A4 group - age: $81.80{\pm}0.60yrs$, height: $152.18{\pm}4.77cm$, weight: $55.80{\pm}7.78kg$). The study method adopted was the 3D analysis with six cameras. Ground type were classifed as gait pattern on flat, ascent and descent ramp. For the statistical analysis, the SPSS 21.0 was used to perform Repeated measured Two-way ANOVA. Results : In velocity of CM, there was faster movement on flat ground. When it came to the velocity of right toe, there was no significance in early mid-swing of right foot, but A4 was the slowest in late mid-swing of right foot on flat ground. In joint angle in left foot strike, the left hip joint and knee joint were more flexed in descent ramp, In addition left and right ankle joints were more plantarflexed in descent ramp, and left ankle joint was more plantarflexed in the over 75 yrs age groups. Conclusion : The higher age group were more flexed in lower body joints during descent ramp.