• 제어로봇시스템학회:학술대회논문집
• /
• 1995.10a
• /
• pp.396-399
• /
• 1995

This paper presents a new formulation of the kinematics of closed-chain mechanisms and its applications to obtaining the kinematic solutions and analyzing the singularities. Closed-chain mechanisms under consideration may have the redundancy in the number of joints. A closed-chain mechanism can be treated as the parallel connection of two open-chains with respect to a point of interest. The kinematics of a closed-chain mechanism is then obtained by imposing the kinematic constraints of the closed-chain on the kinematics of the two open-chains. First, we formulate the kinematics of a closed-chain mechanism using the kinematic constraint between the controllable active joints and the rest of joints, instead of the kinematic constraint between the two open-chains. The kinematic formulation presented in this paper is valid for closed-chain mechanisms with and without the redundancy. Next, based on the derived kinematics of a closed-chain mechanism, we provide the kinematic solutions which are more physically meaningful and less sensitive to numerical instability, and also suggest an effective way to analyze the singularities. Finally, the computational cost associated with the kinematic formulation is analyzed.

• Industrial Engineering and Management Systems
• /
• v.7 no.1
• /
• pp.78-89
• /
• 2008

The need for holistic modeling efforts for returns that capture the extended closed loop supply chain (CLSC) system at strategic as well as operational level has been clearly recognized by the industry and academia. Strategic decision-makers need comprehensive models that can guide them in efficient decision-making to increase the profitability of the entire forward and return chain. Therefore, determination of a near optimal design configuration, which includes the environmental, economical and technological capability factors, is important in strategic decision-making effort that affect the profitability of the closed loop supply chain. In this paper, we adopted an improved system dynamics methodology to tackle strategic issues that affect various performance measures, like market, time/cost, environment etc., for closed loop supply chains. After studying real life implementation issues in CLSC design, we presented guidelines for the PBM (Participative Business Modeling) methodology and presented its extension for the strategic dynamic system modeling of return chains. Finally, we demonstrated the measurement of operational performance by extending SD (system dynamic) application to closed loop supply chain management.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.56-56
• /
• 2010

Using first-principles density-functional theory calculations, we find dramatically different electronic states in the C chains generated on the H-terminated C(111) surface, depending on their length and parity. The infinitely long chain has $\pi$ electrons completely delocalized over the chain, yielding an equal C-C bond length. As the chain length becomes finite, such delocalized $\pi$ electrons are transformed into localized ones. As a result, even-numbered chains exhibit a strong charge-lattice coupling, leading to a bond-alternated structure, while odd-numbered chains show a ferrimagnetic spin ordering with a solitonlike structure. These geometric and electronic features of infinitely and finitely long chains are analogous to those of the closed (benzene) and open (polyacetylene) chains of hydrocarbons, respectively.

• Journal of Mechanical Science and Technology
• /
• v.17 no.12
• /
• pp.1977-1985
• /
• 2003

In the present study, the dynamic modelling of planar mechanisms that consist of a system of rigid bodies is carried out using point coordiantes. The system of rigid bodies is replaced by a dynamically equivalent constrained system of particles. Then for the resulting equivalent system of particles, the concepts of linear and angular momentums are used to generate the equations of motion without either introducing any rotational coordinates or distributing the external forces and force couples over the particles. For the open loop case, the equations of motion are generated recursively along the open chains. For the closed loop case, the system is transformed to open loops by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a multi-branch closed-loop system is chosen to demonstrate the generality and simplicity of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.1
• /
• pp.35-43
• /
• 1996

A computer program for automatic deriving the symbolic equations of motion for robots using the programming language MATHEMATICA has been developed. The program, developed based on the Lagrange formalism, is applicable to the closed chain robots as well as the open chain robots. The closed chains are virtually cut open, and the kinematics and dynamics of the virtual open chain robot are analyzed. The constraints are applied to the virtually cut joints. As a result, the spatial closed chain robot can be considered as a tree structured open chain robot with kinematic constraints. The topology of tree structured open chain robot is described by a FATHER array. The FATHER array of a link indicates the link that is connected in the direction of base link. The constraints are represented by Lagrange multipliers. The parallel robot, DELTA, having three-dimensional closed chains is modeled and simulated to illustrate the approach.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.06a
• /
• pp.201-203
• /
• 2022

Increasing global market of used electric vehicle (EV) battery encourages international firms to establish its subsidiary companies or business units specializing in battery recycling. Such kind of companies predominantly use closed loop supply chain (CLSC) for their operations of battery manufacturing and used battery recycling/reusing in global scale. However, EV battery recycling, as a relatively new industry, makes its global CLSC be exposed to various types of risks, which leads to inefficiency of supply processes and makes supply chains more complicated and vulnerable. Identifying, evaluating, and analyzing possible risks in CLSC has a great importance for optimization and increasing effectiveness for the global supply chain of used EV battery. Itwill assist to elaborate the efficient CLSC management and possible risk mitigation strategies to keep the global EV battery supply chain resilient and sustainable. This study aims to develop a conceptual framework for risk assessment in this new sector. Therefore, it will populate the framework with possible failure modes identified from various literature on EV battery recycling and closed loop supply chains so that future research can validate and utilize the conceptual framework.

• Journal of International Academy of Physical Therapy Research
• /
• v.11 no.4
• /
• pp.2212-2220
• /
• 2020

Background: Repetitive damage to the ankle joint causes chronic ankle instability, and studies comparing the effects of exercise in open and closed chains as a treatment method are very rare. Objectives: To investigate the effects of open and closed kinetic exercises on muscle activity and dynamic balance of ankle joint in adults with chronic ankle instability. Design: Single-blind randomized controlled trial. Methods: The selected 30 subjects are randomly divided into open kinetic chain exercise experimental group (EGI, n=10), closed kinetic chain exercise experimental group (EGII, n=10), and stretching control group (CG, n=10). Open and closed kinetic exercises lasted 30 minutes three times a week for six weeks and stretching exercises performed four actions for 20 seconds and five sets. The measurement tools using surface electromyography to measure muscle activity in the ankle joint. The dynamic balance of the ankle was evaluated using the Y-Balance test. Results: Following the intervention, closed and open kinetic chain exercise group showed significant difference in tibialis anterior and gastrocnemius muscle activity and dynamic balance (P<.05). However, no significant difference in tibialis anterior and gastrocnemius muscle activity and dynamic balance between closed and open kinetic chain exercise group (P<.05). Conclusion: This study provides evidence that closed and open kinetic chain exercise can be presented as an effective exercise for the muscle activity of ankle muscle and dynamic balance of the subject with chronic ankle instability.

• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.2
• /
• pp.215-223
• /
• 2011

Purpose: The purpose of this study was to determine the effect of leg muscle activation by applying proprioceptive neuromuscular facilitation (PNF) arm patterns to unilateral upper extremities under the condition of both open and closed kinetic chains in a seated position. Methods: Twenty-two healthy subjects participated in this study. Four PNF patterns were applied to each subject's unilateral upper extremity. EMG data were collected from the vastus medialis, biceps femoris, tibialis anterior and gastrocnemius. The measured EMG data were digitized and processed to root mean square (RMS) and expressed as percentage maximal voluntary isometric contraction (%MVIC). The data were analyzed using two-way analysis of variance (ANOVA) with repeated measures to determine the statistical significance. Results: The results of this study were summarized as follows: Firstly, in comparison to muscle activation of the biceps femoris, there was a significant increase in the D2 flexion pattern when it was compared with D2 extension pattern and when it was compared with D1 flexion pattern (p<.05). Secondly, there was a significant increase in the muscle activation of the vastus medialis and tibialis anterior with a closed kinetic chain rather than an open kinetic chain (p<.05). Conclusion: In conclusion, in order to increase muscle activation of the biceps femoris, the D2 flexion pattern can be applied, regardless of kinetic chain. In addition, in order to increase muscle activation of the vastus medialis and tibialis anterior, four arm patterns can be applied with a closed kinetic chain.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.8 no.2
• /
• pp.75-86
• /
• 2004

In this study, a recursive algorithm for generating the equations of motion of a chain of rigid rods is presented. The methods rests upon the idea of replacing the rigid body by a dynamically equivalent constrained system of particles. The concepts of linear and angular momentums are used to generate the rigid body equations of motion without either introducing any rotational coordinates or the corresponding transformation matrices. For open-chain, the equations of motion are generated recursively along the serial chains. For closed-chain, the system is transformed to open-chain by cutting suitable kinematic joints with the addition of cut-joints kinematic constraints. An example of a closed-chain of rigid rods is chosen to demonstrate the generality and simplicity of the proposed method.

• Journal of Mechanical Science and Technology
• /
• v.17 no.9
• /
• pp.1287-1296
• /
• 2003

In this paper the dynamic analysis of the Macpherson strut motor-vehicle suspension system is presented. The equations of motion are formulated using a two-step transformation. Initially, the equations of motion are derived for a dynamically equivalent constrained system of particles that replaces the rigid bodies by applying Newton's second law The equations of motion are then transformed to a reduced set in terms of the relative joint variables. Use of both Cartesian and joint variables produces an efficient set of equations without loss of generality For open chains, this process automatically eliminates all of the non-working constraint forces and leads to an efficient solution and integration of the equations of motion. For closed loops, suitable joints should be cut and few cut-joints constraint equations should be included for each closed chain. The chosen suspension includes open and closed loops with quarter-car model. The results of the simulation indicate the simplicity and generality of the dynamic formulation.