• 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.

• The Journal of the Society of Stroke on Korean Medicine
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• v.14 no.1
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• pp.61-70
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• 2013

■ Objectives The goal of this pilot study is to observe the change of gait pattern in a patient after peroneal nerve electrical stimulation(PNST). ■ Methods We analyzed the gait pattern of stroke patient using treadmill gait analysis system before and after PNST for seven weeks. The PNST was carried out for 20minutes every day except Sunday. In addition, the measurement was carried out every Saturday. At the fifth week, the PNST was not carried out to confirm whether the effect of PNST was disappeared immediately when PNST was not applied. ■ Results After PNST, while heel contact time and heel max force increased and forefoot and midfoot max force decreased, the gait parameters such as cadence, velocity, swing phase, stance phase, total double support, step length, stride length, step time, stride time and forefoot contact time, were not changed. ■ Conclusion Gait of a patient with cerebral stroke was changed positively after PNST.

• Geomechanics and Engineering
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• v.38 no.6
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• pp.553-569
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• 2024

In recent tunneling projects, encounters with multi-layered strata have become more frequent as the desired scale of tunneling increases. Despite substantial practical experience, the design of large-diameter shield-driven tunnels often simplifies the surrounding ground as uniform, overlooking the complexities introduced by non-uniform geotechnical factors. This study comparatively analyzed the influence of design factors, particularly segment stiffness and joint parameters, on segmental lining behavior in layered ground conditions using numerical methods. A comprehensive parametric study revealed the significant impact of deformative interaction between the lining and the soft top soil layer on overall tunnel behavior. Permitting lining deformation in the soft soil layer effectively mitigated the induced internal forces but resulted in considerable tunnel lining convergence, adopting a peanut-shaped appearance. From a practical design perspective, application of a soft segment with lower stiffness near the stiff soil layer is an economically advantageous approach, alleviating internal forces within an acceptable convergence level. Notably, around the interfaces between soil layers with different stiffnesses, the induced internal forces in the lining were minimized based on joint rotational stiffness and location. This indicates the possibility of achieving an optimal design for segmental lining joints under layered ground conditions. Additionally, a preliminary design method was proposed, which sequentially optimizes parameters for joints located near soil layer interfaces. Subsequently, a specialized design based on the proposed method for complex multi-layered strata was compared with a conventional design. The results confirmed that the internal force was effectively relieved at an allowable lining deflection level.

• Structural Engineering and Mechanics
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• v.41 no.2
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• pp.299-312
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• 2012

Stiffened coupled shear walls (SCSW) are under axial load resulting from their weight and this axial load affects the behavior of walls because of their excessive height. In this paper, based on the continuum approach, the optimal position of the stiffening beam on the stiffened coupled shear walls is investigated considering the effect of uniformly distributed axial loads. Moreover, the effect of the height of stiffened coupled shear walls on the optimal position of the stiffening beam has been studied with and without considering the axial force effect. A computer program has been developed in MATLAB and numerical examples have been solved to demonstrate the reliability of this method. The effects of the various flexural rigidities of the stiffening beam on the internal forces and the lateral deflection of the structure considering axial force effect have also been investigated.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.57-62
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• 2015

Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing(ECT) is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. The New ECT sensor which can detect inner defects was developed regardless the condition of surface. This sensor is verified to do experiment which measure the loss of induced electromotive force. The loss of induced electromotive force was measured in 5.4% and this low frequency ECT device can detect internal defects at depth 20 mm.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.198-208
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• 1996

The plunge joints of C.V. Joint for vehicle tend to produce a cyclic axial disturbance at a frequency of three of six times shaft speed, in which this distrubance caused by internal frictional effect is related to joint angle, rotational speed, torque, and joint size. This principal axial thrust force might make vehicle shuddered when coinciding with vehicle frequency of tranverse direction, and be one of reasons to have driver feel uncomfortable, unesay, while driving vehicle. The paper makes analysis of axial thrust force & vehicle shudder through computer simulation, comparing the result with experimental data, and reviewing the effect by changing of variables such as dimensions and driving conditions.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.973-992
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• 2016

A direct and relatively simple method for controlling nodal displacements and/or internal bar forces has been developed for prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation, in which structural matrices being built up from matrices of elementary elements. The method is aimed at static shape control of geometrically sensitive structures. The paper discusses identification of the most effective bars for actuation, without incurring violation in bar forces, and also with objective of minimal number of actuators or minimum actuation. The advantages of the method is that the changes for both force and displacement regimes are within a single formulation. The method can also be used for adjustment of bar forces to either reduce instances of high forces or increase low forces (e.g., in a cable nearing slack).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.985-991
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• 2006

For a shear-deformable beam-column element subjected to non-conservative forces. equations of motion and a finite element formulation are presented applying extended Hamilton's principle. The influence of non-conservative force's direction parameter. internal and external damping forces, and shear deformation and rotary inertia effects on divergence and flutter loads of Beck's columns are intensively investigated based on element stiffness. damping and mass matrixes derived for the non-conservative system.

• Journal of Mechanical Science and Technology
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• v.18 no.3
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• pp.471-480
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• 2004

Statistical simulation approaches are proposed to evaluate the shift feeling for a manual transmission. First, shift force simulator for the manual transmission is developed by considering the dynamic models of the external and internal linkage, synchronizer, and drivetrain. It is found that the shift force by the simulator shows a good correlation with the test results. Using the simulator, two kinds of statistical simulation approaches are proposed and the objective parameters that can be used to evaluate the shift feeling quantitatively are obtained. It is expected that the shift force simulator with the statistical approaches, developed in this study can be used as a useful design tool to evaluate the shift feeling in the initial design stage.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.395-398
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• 2006

this paper provides a novel method to start the linear engine coupled linear generator from dead stop to its final steady state operation. This method depends mainly to use the linear generator mounted on the shaft of the linear engine to provide the required thrust force to move and oscillate the linear engine from bottom to top dead centers. It is a cost effective approach to start the internal linear combustion engine using its coupled tubular permanent magnet linear generator proposed here. This linear generator operates in this case in motoring mode, providing the required thrust force by feeding this linear generator phases with currents by using a three phase PWM inverter controlled by position feedback scheme. In order to provide the desired thrust force with specific value and direction, a position feedback is required to control the free piston engine motion through controlling the inverter switches using PWM control scheme.