• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.353-354
• /
• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.317-318
• /
• 2010

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.2 s.54
• /
• pp.137-144
• /
• 2009

This paper provides the results from evaluating the stiffness of Hi-Form joint by an experiment and the system identification method using the dynamic modal data, and the reasonable modeling method of Hi-Form joint which is proposed for improved stair construction recently. Based on the crack pattern and load-displacement relationship and the damage distribution, it can be judged that Hi-Form joint can't fully transfer the forces between the elements linked, and we propose that the joint is modeled as a element which have a stiffness with 50% decrease.

• Korean Journal of Applied Biomechanics
• /
• v.28 no.1
• /
• pp.61-67
• /
• 2018

Objective: The human body is often modelled as a spring-mass system. Lower extremity stiffness has been considered to be one of key factor in the performance enhancement of running, jumping, and hopping involved sports activities. There are several different classification of lower extremity stiffness consisting of vertical stiffness, leg stiffness, joint stiffness, as well as muscle and tendon stiffness. The primary purpose of this paper was to review the literature and describe different stiffness models and discuss applications of stiffness models while engaging in sports activities. In addition, this paper provided a current update of the lower extremity literature as it investigates the relationships between lower extremity stiffness and both functional performance and injury. Summary: Because various methods for measuring lower extremity stiffness are existing, measurements should always be accompanied by a detailed description including type of stiffness, testing method and calculation method. Moreover, investigator should be cautious when comparing lower extremity stiffness from different methods. Some evidence highlights that optimal degree of lower extremity stiffness is required for successful athletic performance. However, the actual magnitude of stiffness required to optimize performance is relatively unexplored. Direct relationship between lower extremity stiffness and lower extremity injuries has not clearly been established yet. Overall, high stiffness is potentially associate risk factors of lower extremity injuries although some of the evidence is controversial. Prospective injures studies are necessary to confirm this relationship. Moreover, further biomechanical and physiological investigation is needed to identify the optimal regulation of the lower limb stiffness behavior and its impact on athletic performance and lower limb injuries.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.243-250
• /
• 2004

This paper reports on the evaluation of the initial stiffness of steel joints using component method as well as experimental tests. The so-called component method corresponds precisely to a simplified mechanical model composed of extensional springs and rigid links, whereby the joint is simulated by an appropriate choice of rigid and flexible components. An application to a cantilever beam-to-column steel joint is presented and compared to the experimental results obtained under cyclic loading condition. Comparison between numerical and experimental results allows to conclude that the numerical model is able to simulate, with a good level of accuracy for initial stiffness, the behaviour of beam-to-column joints.

• The Journal of Korea Robotics Society
• /
• v.2 no.2
• /
• pp.168-177
• /
• 2007

In a number of fields, robots are being used for two purposes: efficiency and safety. Most robots, however, have single-actuator mechanism for each joint, where the tasks are performed with high stiffness. High stiffness causes undesired problems to the environment and robots. This study proposes redundant actuator mechanism as an alternative idea to cope with these problems. In this paper, Double-Actuator Unit (DAU) is implemented at each joint for applications of multi-link manipulators. The DAU is composed of two motors: the positioning actuator and the stiffness modulator, which enables independent control of positioning and compliance. A three-link manipulator with DAUs enables adaptive control of RCC. By modulating the joint stiffness of the manipulator and controlling the position of RCC, we can significantly reduce contact force during assembly tasks and surgical procedures.

• Journal of Korean Foot and Ankle Society
• /
• v.16 no.1
• /
• pp.58-61
• /
• 2012

Motion of the metatarsophalangeal joints is essential for the normal gait. Therefore it is important to recover the motion of normal joint in the treatment of stiffness of the metatarsophalangeal joints. However, there have been no report about the treatment of stiffness of the four lateral lesser metatarsophalangeal joints yet. We report an experience that good clinical and radiographic results were obtained after resection arthroplasty for the post-traumatic stiffness of the four lateral lesser metatarsophalangeal joints.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.6
• /
• pp.657-682
• /
• 2011

This paper presents the dynamic analysis on the joint torque of a finger for the tip pinch task. The dynamic model on finger movement was developed in order to predict the joint torques of an index finger, and the finger was assumed as a three-link planar manipulator. Analysis of the model revealed that the joint stiffness was one of the most important parameters affecting the joint torque. The stiffness of the finger joint was experimentally measured, and it was used in analyzing the finger joint torque required for performing the tip pinch task. The obtained joint torque for the tip pinch task will be used as the design requirements of the finger exoskeletal orthosis actuated by the polymer actuator whose allowable torque limit is relatively low compared to that of a mechanical actuator.

• Structural Engineering and Mechanics
• /
• v.53 no.2
• /
• pp.373-392
• /
• 2015

In the present work, structural joints have been modeled as a pair of translational and rotational springs and frequency equation of the overall system has been developed using sub-structure synthesis. It is shown that using first few natural frequencies of the system, one can obtain a set of over-determined system of equations involving the unknown stiffness parameters. Method of multi-linear regression is then applied to obtain the best estimate of the unknown stiffness parameters. The estimation procedure has been developed first for a two parameter joint model and then for a three parameter model, in which cross coupling terms are also included. Two cases of structural connections have been considered, first with a cantilever beam with support flexibility and then a pair of beams connected through lap joint. The validity of the proposed method is demonstrated through numerical simulation and by experimentation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.5
• /
• pp.1445-1457
• /
• 1996

In building a finite element model of as automotive structure, the pillars and rockers are generally modeled as beam elemnts. The finite elemtns modeling using beam is faster and more efficient than that using shell elemetns. A joint is defined as theintersectio region of beam elemts and generally modeled with coupled rotational springs. In this study, hoint modeling technique is presented. First, the definitions of and anlaysis hypothesis for the joint are defined. Second the evaluation method of the joint stiffness from the static test is proposed. This method is simpler than existing evaluaiton methods. Third, the sensitivity analysis method and updating algorithm forjoint stiffness are presented. To verify these melthods, the finite element results of structural models with rigid joints and rotational spring joints are compared with experimental results.