• Korean Journal of Applied Biomechanics
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• v.34 no.2
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• pp.45-52
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• 2024

Objective: The purpose of this study was to measure the morphological characteristics of the foot and biomechanical variables of the lower extremity joints during vertical jump and investigate the relationship between foot morphology and biomechanics of vertical jump. Method: 24 men in their 20s (age: 22.42 ± 1.41 yrs, height: 173.37 ± 4.61 cm, weight: 72.02 ± 6.21 kg, foot length: 251.70 ± 8.68 mm) participated in the study. Morphological characteristics of the foot included the length of the first toe, the length of the second toe, and the horizontal length from the center of ankle joint to the achilles tendon (Plantar Flexion Moment Arm [PFMA]). Biomechanical variables were measured for plantar flexor strength of the ankle joint and peak angular velocity, moment, and power of the lower extremity joint during vertical jump. Results: There was a significant correlation between the length of the first toe and plantar flexion strength at 30°/s [r=.440, p=.016], the angular velocity of the metatarsophalangeal [MTP] joint [r=-.369, p=.038] while significant correlations between PFMA and the angular velocities of the knee joint [r=.369, p=.038] and ankle joint [r=.420, p=.021] were found. There were also significant correlations between the length of the first toe and the maximum moment of the hip joint [r=.379, p=.034], and the length of the second toe and the power of the hip joint [r=-.391, p=.029]. Finally, significant correlations between PFMA and the power of the ankle joint [r=.424, p=.019] and MTP joint [r=.367, p=.039] were found. Conclusion: Based on the results of this study, the length of the toe and PFMA would be related to the function of the lower extremity joint. Therefore, this should be considered when designing the functional structure of a shoe. Furthermore, this relationship can be applied to intensive training for the plantar flexors and toe flexors to improve power in athletic performance.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.53-61
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• 2003

The purposes of this study were to describe and compare pint moments according to 6 types of gait methods during free speed. 15 volunteers(7 male, 8 female: mean age = 23.33 yrs.) participated and performed 6 types of gait methods. From the 3 types of pint moments of lower extremities(hip, knee, ankle and foot), the following results were made: 1. In left hip pint, the flexion-extension moment was not significantly different, but the adduction-abduction moment and rotation moment were showed different curves during stance phase. 2. In left knee pint, the flexion-extension moment was not significantly different, but the varus-valgus moment and rotation moment were showed different curves during stance phase. 3. In left ankle and foot the dorsiflexion-plantarflexion moment was not significantly different but the varus-valgus moment and rotation moment were showed different curves during stance phase. In conclusion, because weight loading gait with 10-20% of body weight were normal gait patterns, It was inferred that all weight loading gaits did not indicate noxious reactions of human body.

• Physical Therapy Korea
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• v.15 no.2
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• pp.64-72
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• 2008

The purpose of this study was to determine the differences in joint moment in the intact limb of uni-transfemoral amputees and to identify the implications of knee osteoarthritis. As an experimental method, three-dimensional gait analysis was performed on 10 uni-transfemoral amputees and 10 healthy males. Kinematics and kinetics at the hip, knee, and ankle joint were calculated. As a statistical method, independent t-tests were conducted to perform a comparison between the transfemoral amputee group and the control group. The results showed that the external knee adduction moment increased in the transfemoral amputee group (.22 Nm/kg) compared with that of the control group (.13 Nm/kg) at terminal stance (p=.008). External knee flexion moment also increased in the transfemoral amputee group (.24 Nm/kg) but this difference was not statistically significant. External hip flexion moment increased in the transfemoral amputee group (1.35 Nm/kg) compared with that of the control group (.45 Nm/kg) at initial stance, and external hip extension moment decreased in the transfemoral amputee group (-.26 Nm/kg) compared with that of the control group (-.76 Nm/kg) at terminal stance. Although external ankle plantarflexion moment of the transfemoral amputee group increased, it was not found to be statistically significant. The results suggest that the intact limb joint moment of the uni-transfemoral amputees during walking can be different from that of healthy subjects. In conclusion, it was found that there is a link between the increase of external knee adduction moment and the prevalence of knee osteoarthritis in uni-transfemoral amputees. This result is expected to provide some objective data for rehabilitation programs related to knee osteoarthritis in transfemoral amputees.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.369-375
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• 2016

Objective: The purpose of this study was to investigate the possibility of injuries and the types of movement related to damage by body parts, and to prepare for prevention of injuries and development of a training program. Method: For this study, the experiment was conducted according to levels of 60 percentages (ST) and 85 percentages (MA) and 10 subjects from the Korean elite national weightlifting team were included. Furthermore, we analyzed joint moment and muscle activation pattern with three-dimensional video analysis. Ground reaction force and EMG analyses were performed to measure the factors related to injuries and motion. Results: Knee reinjuries such as anterior cruciate ligament damage caused by deterioration of the control ability for the forward movement function of the tibia based on the movement of the biceps femoris when the rectus femoris is activated with the powerful last-pull movement. In particular, athletes with previous or current injuries should perceive a careful contiguity of the ratio of the biceps femoris to the rectus femoris. This shows that athletes can exert five times greater force than the injury threshold in contrast to the inversion moment of the ankle, which is actively performed for a powerful last pull motion and is positively considered in terms of intentional motion. It is activated by excessive adduction and internal rotation moment to avoid excessive abduction and external rotation of the knee at lockout motion. It is an injury risk to muscles and ligaments, causing large adduction moment and internal rotation moment at the knee. Adduction moment in the elbow joint increased to higher than the injury threshold at ST (60% level) in the lockout phase. Hence, all athletes are indicated to be at a high risk of injury of the elbow adductor muscle. Lockout motion is similar to the "high five" posture, and repetitive training in this motion increases the likelihood of injuries because of occurrence of strong internal rotation and adduction of the shoulder. Training volume of lockout motion has to be considered when developing a training program. Conclusion: The important factors related to injury at snatch include B/R rate, muscles to activate the adduction moment and internal rotation moment at the elbow joint in the lockout phase, and muscles to activate the internal rotation moment at the shoulder joint in the lockout phase.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.303-308
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• 2000

The design of column joint is an important part of earthquake resistant design of reinforced concrete moment resisting frames. Beam column joints must provide sufficient stiffness and strength to resist and sustain the loads induced by adjacent beams and columns. This paper investigates the difference of the current design codes which provide a different approach for the design of beam column joint in seismic zone. The model provided by Hitoshi Shiohara(1998) is reviewed in this paper, which provides a good relationship between moment and shear action of interior beam column joint and a role shear reinforcement according to their position.

• Computers and Concrete
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• v.14 no.2
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• pp.109-125
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• 2014

The force transfer mechanism in positive moment continuity details for prestressed concrete girder bridges is investigated in this paper using a three-dimensional detailed finite element model. Positive moment reinforcement in the form of hairpin bars as recommended by the National Cooperative Highway Research Program Report No 519 is incorporated in the model. The cold construction joint that develops at the interface between girder ends and continuity diaphragms is also simulated via contact elements. The model is then subjected to the positive moment and corresponding shear forces that would develop over the service life of the bridge. The stress distribution in the continuity diaphragm and the axial force distribution in the hairpin bars are presented. It was found that due to the asymmetric configuration of the hairpin bars, asymmetric stress distribution develops at the continuity diaphragm, which can be exacerbated by other asymmetric factors such as skewed bridge configurations. It was also observed that when the joint is subjected to a positive moment, the tensile force is transferred from the girder end to the continuity diaphragm only through the hairpin bars due to the lack of contact between the both members at the construction joint. As a result, the stress distribution at girder ends was found to be concentrated around the hairpin bars influence area, rather than be resisted by the entire girder composite section. Finally, the results are used to develop an approach for estimating the cracking moment capacity at girder ends based on a proposed effective moment of inertia.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5766-5772
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• 2011

This study was to investigate the change of gait temporal parameter and ankle joint moment between patients with achilles tendinitis and healthy people. Thus, the purpose of this study is to clarify biomechanical change of gait in patients with achilles tendinitis and to find risk factor for prevention of achilles tendinitis. We recruited 20 patients with an achilles tendinitis and 20 healthy people. While subjects shuttled 5 times on 13 m distance with comfortable pace, we examined gait function marker with three-dimensional gait analysis system. All subject outstepped center of forceplate during gait and calculated ankle joint moment using software. Obtained data was analyzed using SPSS 12.0 software. In results, we confirmed that patients with achilles tendinitis showed reduction of extension moment in early initial phase and reduction of flexion moment in mid-stance on hip joint. and reduction of flexion moment in early initial phase and reduction of extension moment in late phase on knee joint. And we identified that patients with achilles tendinitis showed reduction of dorsiflexion moment in early stance phase, maximal plantarflexion moment in mid stance phase, and dorsiflexion moment in late stance phase. Thus, there are biomechanical changes on gait in patients with achilles tendinitis compared to healthy people. And, in clinical settings, they should focus on changes of gait in patients with achilles tendinitis. Further study will be undertaken for the biomechanical changes of patietns with achilles tendinitis.

• Structural Engineering and Mechanics
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• v.87 no.4
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• pp.391-403
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• 2023

In this study, a new type of self-centering beam-column joint with tapered steel plate links is proposed. Firstly, mechanical property of the basic joint (with the prestressed steel strands only, to provide the self-centering ability) and the combined joint (with both the prestressed steel strands and tapered steel plate links, to provide self-centering and energy dissipation simultaneously) is theoretically analyzed. Then, three joints with different dimensions and combinations of tapered plate links are designed and tested through a series of quasi-static cyclic loading tests. Test results show that a nearly bilinear elastic moment-rotation relationship for the basic joint is obtained. With the addition of tapered steel plate links, typical flag-shape hysteretic curves are obtained, which indicates good self-centering and energy dissipating ability of the combined joint. By installing multiple tapered plate links, stiffness and bearing capacity of the beam-column joint can be enhanced. The theoretical moment-rotation relationships agree well with the test results. A simplified macro model of the proposed joint is developed using OpenSees, which simulates reasonably well its hysteretic behavior.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.6
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• pp.283-292
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• 2015

In the moment frame subjected to earthquake loads, beam-column joint is structurally important for ductile behavior of a system. ACI Committee 352 proposed guidelines for designing beam-column joint details. The guidelines, however, need to be updated because of the lack of data regarding several factors that may improve the performance of joints. The purpose of this study is to investigate the seismic performance of reinforced concrete exterior joints with high-strength materials and unbonded tendons. Three specimens with different joint shear demand-to-strength ratios were constructed and tested, where headed bars were used to anchor the beam bars into the joint. All specimens showed satisfactory seismic behavior including moment strength of 1.3 times the nominal moment, ductile performance (ductility factor = at least 2.4), and sufficiently large dissipated energy.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.13-20
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• 2012

In this study, 5-story structures were designed in accordance with KBC2009 for inelastic time history analysis of RC IMRF. Bending moment-curvature relationship for beam and column was identified with fiber model and bending moment-rotation relationship for beam-column joint was calculated with simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The hysteretic behavior was simulated with three-parameter model suggested in IDARC program. The analytical results showed that the inelastic shear behavior of the joint could be neglected in the structural design for seismic design category C but the structure of category D did not satisfy the criteria of FEMA 356 for collapse prevention performance level.