• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.3
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• pp.153-160
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• 2017

Gait analysis has been conducted in various environments, but the biomechanics during the transition from uphill walking to downhill walking have not been reported. The purpose of this study is to investigate the knee and ankle joint kinematics and kinetics during walking on a triangle-shaped slope compared with those during level walking. Kinematic and kinetic data of eighteen participants were obtained using a force plate and motion capture system. The greater peak ankle dorsiflexion angle and moment and the peak knee extension moment were observed (p<0.05) during both uphill and downhill walking on the triangle-shaped slope. In summary, uphill walking on a triangle-shaped slope, which showed a peak knee flexion of more than $50^{\circ}$ with greater peak knee extension moment, could increase the risk of patellofemoral pain syndrome. Downhill walking on a triangle-shaped slope, which involved greater ankle dorsiflexion excursion and peak ankle dorsiflexion, could cause gastrocnemius muscle strain and Achilles tendon overuse injury.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.203-212
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• 2008

The purpose of this study is to propose appropriate model for 3 staged Didimsae movement to Jajinmori rhythm and to provide information for ideal foot step movements. For the locational change of body center, the height of body center is lowered at the moment of forward step and during forward intersection of the feet, forward direction linear motion is converted to vertical motion to maintain stability. Speed change of body center reduces flow of body on step forward moment and controls rapid forward movement for stabled movement and position when preventing fast forward horizontal direction movement of centroid speed while knee joint and foot joint are vertically risen for heel bone contacts the ground. For angle changes of joints, in order to prevent hyperextension of lower leg, hip joint is extended and knee joint is curved to secure stability of movement for smooth curves and extension. When centroid of foot joint is moved from top of the feet to whole foot sole and when left foot makes dorsal curve, stabled movement is accomplished.

• Physical Therapy Korea
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• v.25 no.3
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• pp.19-26
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• 2018

Background: Genu varum is also known as bow leg. It is a deformity wherein there is lateral bowing of the legs at the knee. it does give rise to pain, and persistent bowing can often give rise to discomfort in knees, hips and ankles. Objects: This study investigated the effect of narrow squats on the knee joint during a gait and distance between the knees of person with genu varum. Methods: This study analyzed 23 patient with genu varum that grade III, 12 narrow squat group and 11 genenal squat group in motion analysis laboratory. The subjects of experiment took gait before and after intervention, the range of joint motion, moment of knee joint adduction, power, distance of the knees were measured. And in order to make an analysis between groups, an paiered t-test and independent t-test was carried out. For statistical significance testing, it was decided that significance level ${\alpha}$ be .05. Results: It was shown that the group of narrow squat exercise significantly decreased in distance of knees (p<.05),In moment of adduction of knee joint, it was shown to significantly decrease in two groups (p<.05), was significantly decreased in adduction, abduction, and rotation (p<.05). In relation of peak-knee adduction moment and valgus angle, there was significant decrease in narrow squat group (p<.05). Conclusion: When the above result of study were examined, a narrow squat exercise given to the genu varum patients significantly decreased the distance between the knees, range of knee adduction and abduction, knee adduction moment, knee power. And stability gains through the decrease of excursion of knee medial part be effective for the correction of genu varum deformation.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.85-90
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• 2013

Efficient gait is compensate for a lack of exercise, but the wrong walking can cause disease that joints, muscles, brain and body structure(Scott & Winter, 1990). Also many researchers has been studied gait of positive mechanism using analytical methods kinetic, kinematic. This study is to identify nature of knee adduction moment, depending on different foot progression angle and the movement of rotation of pelvis and body. Health study subject conducted intended walking with three different angles. The subjects of this study classified three types of walking; walk erect, pigeon-toed walk and an out-toed gait. Ten university students of K without previous operation and disease record selected for this study. For accuracy of this study, three types of walking carried out five times with 3D image analysis and using analysis of ground reaction force to analyze nature of knee adduction moment and the movement of rotation of pelvis and body. Firstly, the HC(heel contact) section value of intended walk erect, pigeon-toed walk and an out-toed gait was not shown statistically significant difference but TO(toe off) section value was shown that the pigeon-toed walk statistically significant. The value of pigeon-toed walk was smallest knee adduction moment(p< 0.005). Secondly, X axis was the change of rotation movement body and pelvis when walk erect, pigeon-toed walk and an out-toed gait. Shown statistically Y axis was not shown statistically significant but Z axis statistically significant(p<0.05). These result show the significant differences on TO section when walking moment reaches HC, it decides the walking types and rotates the foot.

• Korean Journal of Applied Biomechanics
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• v.33 no.3
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• pp.110-117
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• 2023

Objective: The purpose of this study was to find out kinematic and kinetic differences the lower extremity joint according to the landing type during vertical jump movement after jump landing, and to present an efficient landing method to reduce the incidence of injury in youth players. Method: Total of 24 Youth players under Korean Sport and Olympic Committee, who used either heel contact landing (HCG) or toe contact landing (TCG) participated in this study (HCG (12): CG height: 168.7 ± 9.7 cm, weight: 60.9 ± 11.6 kg, age: 14.1 ± 0.9 yrs., career: 4.3 ± 2.9 yrs., TCG height: 174.8 ± 4.9 cm, weight: 66.9 ± 9.9 kg, age 13.9 ± 0.8 yrs., career: 4.7 ± 2.0 yrs.). Participants were asked to perform jump landing consecutively followed by vertical jump. A 3-dimensional motion analysis with 19 infrared cameras and 2 force plates was performed in this study. To find out the significance between two landing styles independent t-test was performed and significance level was set at .05. Results: HCG showed a significantly higher dorsi flexion, extension and flexion angle at ankle, knee and hip joints, respectively compared with those of TCG (p<.05). Also, HCG revealed reduced RoM at ankle joint while it showed increased RoM at knee joint compared to TCG (p<.05). In addition, HGC showed greater peak force, a loading rate, and impulse than those of TCG (p<.05). Finally, greater planta flexion moment was revealed in TCG compared to HCG at ankle joint. For the knee joint HCG showed extension and flexion moment in E1 and E2, respectively, while TCG showed opposite results. Conclusion: Compared to toe contact landing, the heel contact landing is not expected to have an advantage in terms of absorbing and dispersing the impact of contact with the ground to the joint. If these movements continuously used, performance may deteriorate, including injuries, so it is believed that education on safe landing methods is needed for young athletes whose musculoskeletal growth is not fully mature.

• Korean Journal of Applied Biomechanics
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• v.24 no.2
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• pp.121-129
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• 2014

The purpose of this study was to investigate the effect of the toe headings on the biomechanics of knee joint in drop landing in an attempt to find the potential risk of non-contact anterior cruciate ligament (ACL) injury. Seventeen male college students ($20.5{\pm}1.1$ yrs; $175.2{\pm}6.4$ cm; $68.8{\pm}5.8$ kg), having no neuromuscular injury within an year, participated in this study. Three different toe headings such as toe-in (TI), neutral (N), and toe-out (TO) positions were tested. Motion capturing system consisting of eight high speed cameras and two force platforms were used to collect three-dimensional motion data and ground reaction force data during landing. Results indicated joint angles and peak joint moments were significantly affected by the toe headings. TI position produced larger valgus angle due to reduce knee distance in addition to higher flexion and valgus moment than other positions, which was somewhat vulnerable to the potential risk of non-contact ACL injury. TO position caused the largest internal rotation angle with smaller joint moments. Therefore, it is recommended that athletes need to land on the ground with neutral toe-heading position as possible in order to minimize the potential risk of non-contact ACL injury.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.35-41
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• 2008

The structural stability for preliminary model of supersonic rocket which has large L/D ratio is investigated. Large L/D ratio can cause a critical problem on the structural stability by the increase of bending-moment. By using the ANSYS and the CFX codes, we inspected the structural stability for Ma=2 and angle of attack for $20^{\circ}$. The optimum number of bolts and their joints required on the rocket surface are predicted.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.393-397
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• 1997

본 연구에서는 손동작(Hand Motion)과 수작업(Manual Task) 분석에 VR환경에서 사용되는 각도 측정 장갑(3-D Glove)을 이용하는 방법을 제안하였다. 본 연구에서 개발된 손동작(Hand Motion)과 수작업(Manual Task)의 분석 시스템은 18-sensor $Cyberglove^{TM}$정 시스템으로부터 측정된 angle data를 기초로 손동작이나 수작업에 대한 totalmuscle moment값과 total muscle excursion값을 구하고, digit와 joint의 moment값을 X,Y.Z방향별고 구하는 기능을 가지고 있다. 시스템의 구성은 : (1) $Cyberglove^{TM}$ System과 분석 시스템의 digital data 처리를 기반으로 하는 손동작의 측정 시스템 ; (2) $Cyberglove^{TM}$ System에서 얻어진 자료를 바탕으로 3차원 공간에서 손동작을 표현할 수 있는 Kinematic Hand Model ; (3) Hand Model과 $Cyberglove^{TM}$ Systme을 기반으로 3차원에서 손동작의 역학적 분석을 할 수 있는 3-D Hand Biomechanical Model ; 등으로 되어있다. 본 시스템은 Telerobotics, Medicine, Virtual Reality 등 다양한 분야에 응용이 가능하며, 수작업에 관련되는 Product Design, Manual Control Device, Computer I/O Device의 설계에도 도움이 될 것으로 기대된다.

• Korean Journal of Applied Biomechanics
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• v.28 no.3
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• pp.175-180
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• 2018

Objective: Anterior cruciate ligament reconstruction (ACLR) has been considered the primary treatment for anterior cruciate ligament (ACL) injured patient. However, there is little biomechanical evidence regarding bilateral knee joint biomechanics during landing and cutting task after ACLR. Method: Eighteen females with ACLR participated in this investigation. Double leg jump landing (DLJL) and single leg jump cut (SLJC) biomechanics were assessed. Results: During DLJL, the healthy knee showed greater knee valgus angle at initial contact ($^{\circ}$) compared to the injured knee (Injured: $2.93{\pm}2.59$, Healthy: $4.20{\pm}2.46$, t=2.957, p=0.009). There was a significant difference in anterior tibial shear force ($N{\times}N^{-1}$) with greater in the injured knee (Injured: $1.41{\pm}0.39$, Healthy: $1.30{\pm}0.35$, t=2.201, p=0.042). During SLJC, injured knee showed greater knee extension moment ($N^*m{\times}[N^*m]^{-1}$) compared to healthy knee (Injured: $0.51{\pm}0.19$, Healthy: $0.47{\pm}0.17$, t=2.761, p=0.013). However, there was no significant differences between the knees in the other variables. Conclusion: ACLRfemales exhibited a greater knee valgus angle at initial contact and lesser anterior tibial shear force on the healthy knee during double leg jump landing. In addition, ACLR females showed a greater knee extension moment on the injured knee during single leg jump cut.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.55-61
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• 2018

The purpose of this study was to analyze the biomechanical differences of lower extremity joints of the frontal plane during sidestep cutting in male and female Judo athletes. In the knee and hip joint, the female group showed a smaller angle than the male group at the time of IC(initial contact). But peak knee joint adduction moment of female group was greater than male group(p<.05). Therefore, female Judo athletes were more likely to injure their knees at the point where their initial foot contacted the ground than male athletes during sidestep cutting.