• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.581-592
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• 2009

The purpose of this study is to examine the effect of the functional shoes through the kinetic comparison of normal-design running shoes and spring-loaded running shoes. For this, 12 healthy females from the age from 30 to 40 years participated in the EMG and ground reaction force experiment with testing kinetic variables. 12 subjects walked at the velocity of 1.7m/s. After analyzing variables in the spring-loaded running shoes and normal-design running shoes, the following conclusions were obtained; For the ground reaction force, spring-loaded running shoes have larger antero-posterior GRF than normal-design running shoes in the first and second apexes of antero-posterior ground reaction force. For the analysis of EMG, spring-loaded running shoes showed the higher muscle activation of rectus femoris muscle than norma-design running shoes. So the spring-loaded running shoes help improvement muscle strength of knee extensor.

• Physical Therapy Korea
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• v.12 no.1
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• pp.28-35
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• 2005

The purpose of this study was to determine whether gender differences existed in knee valgus kinematics in college students when performing a vertical drop landing. The hypothesis of this study was that females would demonstrate greater knee valgus motion. These differences in knee valgus motion may be indicative of decreased dynamic knee joint control in females. This study compared the initial knee valgus angle and maximum knee valgus angle at the instant of impact on vertical drop landings between healthy men and women. In this study, 60 participants (30 males, 30 females) dropped from a height of 43 cm. A digital camera and two-dimensional video motion analysis software were used to analyze the kinematic data. There was significant difference in the mean knee valgus angle at initial contact landing between the two groups (Mean=$7.88^{\circ}$, SD=$4.24^{\circ}$ in males, Mean=$12.93^{\circ}$, SD=$2.89^{\circ}$ in females). The range of knee valgus angle on landing (Mean=$3.25^{\circ}$, SD=$5.72^{\circ}$ in males, Mean=$11.44^{\circ}$, SD=$6.39^{\circ}$ in females) was differed significantly (p<.05). The maximal angle of knee valgus on landing (Mean=$10.91^{\circ}$, SD=$6.89^{\circ}$ in males, Mean=$24.25^{\circ}$, SD=$6.38^{\circ}$ in females) was also differed significantly (p<.05). The females landed with a larger range of knee valgus motion than the males and this might have increased the likelihood of a knee injury. The absence of dynamic knee joint stability may be responsible for increased rates of knee injury in females. No method for accurate and practical screening and identification of athletes at increased risk of ACL injury is currently available to target those individuals that would benefit from neuromuscular training before sports participation.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.51-63
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• 2004

The purpose of this study was to investigate a three dimensional kinematic variables about the last stride and the release phase of the throwing technique for female javelin throwers. For the motion analysis, Six female javelin throwers were used as subjects. Three-dimensional coordinates were collected using the Kwon3D Motion Analysis Package Version 2.1 Program. Two S-VHS Video Cameras were used to record the locations and orientations of control object and the performances of the subjects at a frequency of 6.0 HZ. After the kinematic variables such as the time, the distance, the velocity, and the angle were analyzed about the last stride and release phase, the followings were achieved; 1. For the effectively javelin throwing, the subjects appeared to do long the approach time in the phasel of landing phase, and short the delivery time in release phase 2. In the release event, the other subjects except for subject A appeared to throwing in the lower condition than the height of themselves. This result showed to slow the projecion velocity. 3. For increase the projection vcelocity of the upper extremity joint in the release event, it appeared to do extend rather the shoulder angle than increase the extension of elbow joint. 4. The body of COG angle showed to gradually increase nearly at the vertical axis in the release event. But the front lean angle of trunk showed a small angle compare to increase of the body of COG angle. Therefore for the effectively momentum transmission of the whole body in the javelin, the front and back lean angle of trunk appeared to do fastly transfer the angle displacement in the arch posture or the crescent condition during the deliverly motion of the release phase.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.161-172
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• 2004

본 연구의 목적은 각기 다른 수직 점프 동작 시 근육의 길이와 근육의 수축속도 변화를 비교 분석하는데 있다. 피험자의 운동학적 변인들을 분석하기 위해 2대의 고감도 카메라를 (60 Hz, Panasonic AG455) 사용하여 점프 동작을 촬영하였다. 대퇴직근, 내측광근, 외측광근, 중간광근, 대퇴이두근(단두), 내측과 외측 비복근의 길이와 근수축 속도는 Brand et al. (1982)에 의해 제시되어진 하지근 기시 정지점의 3차원 좌표값과 동작분석을 통한 하지 분절간의 회전 및 변환행렬을 사용하여 측정되어졌다. 일반적인 근육 길이와 수축속도의 변화 형태는 각기 다른 점프간에 매우 유사한 형태를 보였다. 상승기 초기에 대퇴사두근의 길이가 최대인것으로 나타났으며, 이에 반해 대퇴이두근과 내외측 비복근은 공중 동작이 발생하는 시점에 근의 길이가 최대인 것으로 나타났다. 근육의 길이 변화 범위는 대퇴직근이 35.9에서 47.5 cm, 외측광근이 29.4에서 38.8 cm, 중간광근이 31.5에서 38.0 cm, 내측광근이 30.9에서 38.6 cm, 대퇴이두근이 21.3에서 39.1 cm, 외측비복근이 31.4에서 33.5 cm, 내측비복근이 30.5에서 33.2 cm인 것으로 나타났다. SQ와 CMJ에서는 대퇴사두근의 최대 단축성 수축 속도와 대퇴이두근과 내외측 비복근의 최대 신장성 수축이 공중동작이 발생하기 바로 전에 이루어졌다. 대퇴사두근의 최대 신장성 수축과 대퇴이두근과 내외측 비복근의 최대 단축성 수축은 일반적으로 피험자가 착지하는 순간에 발생되어졌다. 그러나 HJ와 DJ에서는 대퇴사두근의 최대 신장성 추축과 대퇴이두근과 내외측 비복근의 최대 신장성 수축이 하강기 초반에 발생되어졌다.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.1-6
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• 2020

This study is about the safe arm posture in case of emergency escape using the vertical dive rescue sack at the fire site. The experimental results are as follows. First, the arms extended upward contact with the endothelium and narrowing part of the rescue sack minimized the scratches did not occur. Second, the bent position with both arms open was subject to light abrasions of on the elbows due to friction between the elbows and the scapula and the endothelium. Third, in the posture where both arms were gathered in the chest, the body passed through the narrowing part and friction between the bag's narrowing part, All subjects had light abrasions on their elbows. Fourth, because the arms are lowered, the legs are extended to the width of the shoulders when descending, so that the back of the hand has friction with the narrowing part of the bag and the endothelial skin. Finally, posture with both arms below the front increased the volume of the front of the body, resulting in a slight back injury. As a future research task, it is necessary to study the proper posture of legs and the posture of landing on the ground.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.405-411
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• 2012

The purpose of this study was to determine the effects of landing height information on landing strategy during a drop landing. Ten healthy male subjects(age: $22.1{\pm}1.9year$, height: $178.4{\pm}7.8cm$, mass: $75.3{\pm}9.4kg$) participated in this study. Each participant was asked to jump with both legs off a 40 cm high box on one of the three plates with different thickness (0 cm, 13 cm, 26 cm). In the first condition, subjects were given both cognitive and visual information about the jumping heights. In the second, they were given only cognitive information without visual one, and in the third, no information about the height was provided to subjects. (Only the data collected from the 40 cm height landing were analyzed and reported in the present study.) The results showed that landing strategies during a double-leg drop landing from 40 cm height were not significantly affected by visual and cognitive information blockages. Also, there were no statistically significant differences in landing strategies between the three conditions even though the mean differences attained in this study seemed to warrant further studies investigating the relationship between landing strategies and cognitive information.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.429-435
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• 2012

The purpose of this study was to determine the biomechanical effect of wearing carbon nanotube-based insole on cushioning and muscle tuning during drop landing. Twenty male university students(age: $21.2{\pm}1.5yrs$, height: $175.4{\pm}4.7cm$, weight: $70.2{\pm}5.8kg$) who have no musculoskeletal disorder were recruited as the subjects. Average axial strain, average shear strain, inversion angle, linear velocity, angular velocity, vertical GRF and loading rate were determined for each trial. For each dependent variable, a one-way analysis of variance(ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions(p<.05). The results showed that Average axial strain of line 4 was significantly less in CNT compared with EVA and PU during IP phase. The average shear strain was less in CNT compared with EVA and PU during other phases. The inversion angle was increased in CNT compared with EVA and PU during all phase. In linear velocity, angular velocity, vertical GRF and loading rate, there were no significant difference between the three groups. This result seems that fine particle of carbon nanotube couldn't make geometric form which can absolve impact force by increasing density through eliminating voids of forms. Thus, searching for methods that keep voids of forms may play a pivotal role in developing of insole. This has led to suggestions of the need for further biomechanical analysis to these factors.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.375-383
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• 2014

The purpose of this study was to assess the inter-segmental trunk motion during which multi-segmental movements of the spinal column was designed to interpret the effect of segmentation on the total measured spine motion. Also it analyzed the relative motion at three types of the spine models in drop landing. A secondary goal was to determine the intrinsic algorithmic errors of spine motion and the usefulness of such an approach as a tool to assess spinal motions. College students in the soccer team were selected the ten males with no history of spine symptoms or injuries. Each subject was given a fifteen minute adaptation period of drop landing on the 30cm height box. Inter-segmental spine motion were collected Vicon Motion Capture System (250 Hz) and synchronized with GRF data (1000 Hz). The result shows that Model III has a more increased range of motion (ROM) than Model I and Model II. And the Lagrange energy has significant difference of at E3 and E4 (p<.05). This study can be concluded that there are differences in the three models of algorithm during the phase of load absorption. Especially, Model III shows proper spine motion for the inter-segmental joint motion with the interaction effects using the seven segments. Model III shows more proper observed values about dynamic equilibrium than Model I & Model II. The findings have shown that the dynamic stability strategy of Model III toward multi-directional spinal motion supports for better function of the inter-segmental motor-control than the Model I and Model II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3834-3842
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• 2011

The purpose of this study is to analyze the kinematic characteristics of children with Down syndrome got congenitally joint laxity and muscle hypotonic. The subjects are boys with Down syndrome and don't have the other disabilities. We got three dimensional position data and then calculated spatiotemporal and kinematic variables during walking on treadmill used increasingly for gait analysis and training. In result, in order to overcome their gait instability due to their musculoskeletal characteristics they walked with hip, knee and ankle joints more flexed than the typical gait pattern, and on the propulsion phase they extend the lower limb joints less than the typical, result in propel the body less than. The reason is that the more is the propulsion by extending the joints, the greater is the reaction force from the ground on heel contact. This result is expected to be used to develop the training program for intensification of musculoskeletal system aim to improve the other musculoskeletal disabilities as well as Down syndrome.

• Korean Journal of Applied Biomechanics
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• v.32 no.1
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• pp.9-16
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• 2022

Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing. Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05. Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure. Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of non-contact knee injury as well as the risk of lateral ankle sprain during forward jump landing.