• Journal of Mechanical Science and Technology
• /
• v.19 no.spc1
• /
• pp.444-451
• /
• 2005

The analysis of human arm motion during steering maneuver is carried out for investigation of man-machine interface of driver and steering system Each arm is modeled as interconnection of upper arm, lower arm, and hand by rotational joints that can properly represents permissible joint motion, and both arms are connected to a steering wheel through spring and damper at the contact points. The joint motion law during steering motion is determined through the measurement of each arm movement, and subsequent inverse kinematic analysis. Combining the joint motion law and inverse dynamic analysis, joint stiffness of arm is estimated. Arm dynamic analysis model for steering maneuver is setup, and is validated through the comparison with experimentally measured data, which shows relatively good agreement. To demonstrate the usefulness of the arm model, it is applied to study the effect of steering column angle on the steering motion.

• Tunnel and Underground Space
• /
• v.7 no.1
• /
• pp.65-74
• /
• 1997

Underground structures show different behaviors depending upon the space and the mechanical characteristics of discontinuities, such as joints, beddings, faults and shear zone. Desingning the rock structeres without considering the significance of these discontinuities can lead to false conclusions. This paper includes study on the following topics; the numerical analysis of continuous rock and discontinuous rock around a tunnel, the influences on shotcrete moment and rock-bolt axial force of tunnel due to different joint orientation and stiffness.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1993.04a
• /
• pp.151-157
• /
• 1993

In this paper a useful method on evaluating the joint stiffness of bolted memeber was introduced using optimization technique on the basis of Finite Element Method. A finite element model having one directional gap element at bo undary area was introduced to compensate the prying force in jointed members which might caused by geometrical configuration of members. Results showed a good aggrement with classical method in certain range and will be available to definine the design margine of pre-load design.

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

• The Journal of Korean Physical Therapy
• /
• v.36 no.1
• /
• pp.27-32
• /
• 2024

Purpose: This study was conducted to verify the effect of applying a pressure biofeedback unit on walking ability and knee joint function while performing knee joint extensor strengthening exercises using resistance exercise equipment in total knee replacement (TKR) patients. Methods: This study was conducted on twelve patients receiving rehabilitation treatment after being admitted to a rehabilitation hospital post-TKR. Of these, six were allocated to a feedback group with a pressure biofeedback unit, and the other 6 were allocated to a control group without a pressure biofeedback unit. The subjects performed an exercise program for 45 minutes per session, five times a week, for two weeks. Walking ability and knee joint function were evaluated and analyzed before and after exercise. Results: The feedback group showed significantly better improvements in walking speed, gait cycle, step length on the non-operation side, time on the foot on the operation side, K-WOMAC stiffness, and K-WOMAC function than the control group (p<0.05). Conclusion: When strengthening the knee joint extensor muscles using resistance exercise equipment in TKR patients, the provision of a pressure biofeedback unit was found to improve walking ability and knee joint function by inducing concentric-eccentric contraction of the knee joint extensor muscles. Therefore, the study shows that exercise based on the provision of a pressure biofeedback unit should be considered when strengthening knee joint extensor muscles to improve the walking ability and knee joint function of TKR patients in clinical practice.

• Journal of Acupuncture Research
• /
• v.20 no.2
• /
• pp.77-84
• /
• 2003

Objective : In order to study the effects of bee venom(BV) on the pain, edema, and acute inflammatory reactant of rheumatoid arthritis(RA) patients. Methods : Patients with RA who met the ACR(American College of Rheumatology) 1987 revised criteria for the diagnosis of RA were treated with the BV therapy twice a week for 3 months. Tender joint counts, swollen joint counts, Visual analog scale(VAS), morning in stiffness, ESR, C-reactive protein(CRP) were analyzed before and after BV therapy. Results : The results as follows: 1. Tender joint counts in patients after BV therapy were significantly lower than those before BV therapy($9.0{\pm}7.9$ vs $15{\pm}11.4$, p=0.002). 2. Swollen joint counts of the patients after BV therapy were significantly lower than those before BV therapy ($5.0{\pm}6.1$ vs $1.5{\pm}2.3$, p=0.001). 3. VAS in patients after BV therapy was significantly lower than before BV therapy($60.8{\pm}17.6$ vs $38.0{\pm}15.9$, p=0.000). 4. Duration of morning stiffness in patients after BV therapy was significantly reduced compared with that before BV therapy($119.1{\pm}112.6min$ vs $59.0{\pm}89.7min$, p=0.009). 5. ESR and CRP were not significantly changed before and after BV therapy, suggesting BV itself could make inflammatory reaction as well as therapeutic effect. Conclusions: BV therapy improved tender joint counts, swollen joint counts and duration of morning stiffness in this study, and further study is needed in log-term effect of BV therapy.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.2
• /
• pp.104-112
• /
• 2012

The failure of tenon in a traditional wood-framed structure may collapse of the entire structure. This study evaluates the strength and stiffness of tenon joints between the beams and pillars through experimental study and suggests reinforcing method of the tenon joint without dismantling the main structures. The main experimental parameters are the number, distance, shape, and inserting depth of spiral-shaped reinforcing steels. As the thickness of the tenon in beams increases, the strength and the initial shear stiffness of the joint increases and, however, the tenons in pillar becomes weaker, resulting in the safety problem of the structure. It is recommended that three spiral-shaped reinforcing steels be placed in the central parts of the tenon to effectively improve the strength and the shear stiffness of the joint.

• PNF and Movement
• /
• v.18 no.3
• /
• pp.323-331
• /
• 2020

Purpose: This study was conducted to determine the effects of motion taping on muscle activity and the WOMAC in a rehabilitation exercise program for elderly women with knee joint osteoarthritis. Methods: The subjects were 28 elderly women aged over 65 years with knee joint osteoarthritis. The subjects were divided into two groups: one experimental and one control group. During the study period, a total of 26 patients completed the experiment, with one drop each from the experimental group and control group. The experimental group applied motion taping and conducted a rehabilitation exercise program. The control group experienced a rehabilitation exercise program without motion taping. The rehabilitation exercise program consisted of warm-up exercises, maximum isometric exercises, the range of motion of the joints, and leg stretching exercises. The intervention was conducted three times a week for six weeks. To investigate the effects of the intervention, muscle activity and the WOMAC were measured. The WOMAC is a tool that can be used to evaluate the pain, stiffness, and physical function of osteoarthritis patients; it has 29 items in three areas. Results: The change in muscle activity according to the intervention showed a statistically significant increase in both the experimental group and control group. The WOMAC also showed statistically significant changes in terms of pain, stiffness, and physical function in both the experimental and control groups. The experimental group showed a greater functional improvement than the control group. Conclusion: For older women with osteoarthritis of the knee, a rehabilitation exercise program is a good intervention. When motion-taping is applied, it is considered to be an intervention program that can be expected to have a better effect on knee joint osteoarthritis.

• Structural Engineering and Mechanics
• /
• v.88 no.5
• /
• pp.481-492
• /
• 2023

The past earthquakes revealed the importance of the design of moment-resisting reinforced concrete framed structures with ductile behavior. Due to seismic activity, failures in framed structures are widespread in beam-column joints. Hence, the joints must be designed to possess sufficient strength and stiffness. This paper investigates the effects of fibers on the ductility of hybrid fiber reinforced self-compacting concrete (HFRSCC) when subjected to seismic actions; overcoming bottlenecks at the beam-column joints has been studied by adding low modulus sisal fiber and high modulus steel fiber. For this, the optimized dose of hooked end steel fiber content (1.5%) was kept constant, and the sisal fiber content was varied at the rate of 0.1%, up to 0.3%. The seismic performance parameters, such as load-displacement behavior, ductility, energy absorption capacity, stiffness degradation, and energy dissipation capacity, were studied. The ductility factor and the cumulative energy dissipation capacity of the hybrid fiber (steel fiber, 1.5% and sisal fiber, 0.2%) added beam-column joint specimen is 100% and 121% greater than the control specimen, respectively. And also the stiffness of the hybrid fiber reinforced specimen is 100% higher than the control specimen. Thus, the test results showed that adding hybrid fibers instead of mono fibers could significantly enhance the seismic performance parameters. Therefore, the hybrid fiber reinforced concrete with 1.5% steel and 0.2% sisal fiber can be effectively used to design structures in seismic-prone areas.

• Earthquakes and Structures
• /
• v.15 no.5
• /
• pp.499-511
• /
• 2018

This paper aims to investigate the seismic performance of the prestressed steel strips retrofitted RC beam-column joints. Two series of joint specimens were conducted under compression load and reversed cyclic loading through quasi-static tests. Based on the test results, the seismic behavior of the strengthened joints specimens in terms of the failure modes, hysteresis response, bearing capacity, ductility, stiffness degradation, energy dissipation performance and damage level were focused. Moreover, the effects of the amount of the prestressed steel strips and the axial compression ratio on seismic performance of retrofitted specimens were analyzed. It was shown that the prestressed steel strips retrofitting method could significantly improve the seismic behavior of the RC joint because of the large confinement provided by prestressed steel strips in beam-column joints. The decrease of the spacing and the increase of the layer number of the prestressed steel strips could result in a better seismic performance of the retrofitted joint specimens. Moreover, increasing the axial compression ration could enhance the peak load, stiffness and the energy performance of the joint specimens. Furthermore, by comparison with the specimens reinforced with CFRP sheets, the specimens reinforced with prestressed steel strips was slightly better in seismic performance and cost-saving in material and labor. Therefore, this prestressed steel strips retrofitting method is quite helpful to enhance the seismic behavior of the RC beam-column joints with reducing the cost and engineering time.