• Structural Engineering and Mechanics
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• v.82 no.4
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• pp.503-515
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• 2022

The multi-rigid-body matrix method (MRBMM) is a generalized modeling method for obtaining the displacements, forces, and dynamic characteristics of a compliant mechanism without performing inner-force analysis. The method discretizes a compliant mechanism of any type into flexure hinges and rigid bodies by implementing a multi-body mass-spring model using coordinate transformations in a matrix form. However, in this method, the deformations of bodies that are assumed to be rigid are inherently omitted. Consequently, it may yield erroneous results in certain mechanisms. In this paper, we present a multi-compliant-body matrix-method (MCBMM) that considers a rigid body as a compliant element, while retaining the generalized framework of the MRBMM. In the MCBMM, a rigid body in the MRBMM is segmented into a certain number of body nodes and flexure hinges. The proposed method was verified using two examples: the first (an XY positioning stage) demonstrated that the MCBMM outperforms the MRBMM in estimating the static deformation and dynamic mode. In the second example (a bridge-type displacement amplification mechanism), the MCBMM estimated the displacement amplification ratio more accurately than several previously proposed modeling methods.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.209-215
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• 2022

In this paper, a forearm Mechanism design inspired by ligamentous structure of the human body is proposed. The proposed mechanism consists of four rigid bodies and fourteen wires without any mechanical joints. Actually, the mechanism is based on the concept of the tensegrity structure. Therefore, the proposed mechanism has inherently compliant characteristics due to the flexibility of the wires composing the structure. Rigid bodies and wires of the mechanism mimic bones and major ligaments in the forearm of the human. The proposed mechanism is classified as one of the interconnected hybrid flexure systems. The analysis method of the degree of freedom (DOF) of the proposed mechanism is also introduced through analyzing technique of the interconnected hybrid flexure systems, in this paper. Ultimately, the proposed mechanism, whose structure is complicated with rigid bodies and wires, mathematically drives that it has 3-DOFs.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2165-2172
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• 1995

Optimization of mesh discretization has been proposed to improve the accuracy of limit analysis solution of collapse load by using the Rigid Body Spring Model(R. B. S. M) under the plane strain condition. Moreover, the fracture behaviour of materials was investigated by employing the fracture mechanism of a spring connecting the triangular rigid body element. It has been clarified that the collapse load and the geometry of slip boundary for optimized mesh discretization were close to those of the slip line solution. Further, the wedge-shaped fracture of a cylinder under a lateral load and the central fracture of a strip in the drawing process were well simulated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1699-1703
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• 2000

While the booming occurs in a cabin, the powertrain and subframes which are the main sources and paths of the booming, show the rigid body motions. This paper presents a technique to predict the booming noise in a car using the rigid body information of the important parts. The rigid body information comes from the CAD data, from which we can predict the response of the complex system. Since the mechanism of this technique is very similar to the finite element formulation, we can apply it to the complex system with ease.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.182-189
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• 2012

This study suggests a dynamic design process for deciding properly design parameters of a mass-spring type Wave Energy Converter (WEC) to achieve sufficient energy conversion from wave to power generator. The WEC mechanism, in this research, consists of a rigid sprung body, a platform, suspension springs and dampers. The rigid sprung body is supported on the platform via springs and dampers and vibrates translationally in the heave direction under wave excitation. At last the resulting heave motion of the sprung body is transmitted to rotating motion of the electric generator by rack and pinion, and transmission gears. For the purpose of vibration analysis, the WEC mechanism has been simply modelled as a mass-spring-damper system under harmonic base excitation. Its maximum displacement transmissibility and steady state response can be determined by using elementary vibration theory if the harmonic ocean wave data were provided. With the vibration analysis results, the suggested dynamic design process of WEC can determine all the design parameters of the WEC mechanism, such as sprung body mass, suspension spring constant, and damping coefficient that can give sufficient relative displacement transmissibility and the associated inertia moment to drive the electric generator and transmission gears.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.745-750
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• 2012

This study extends the constraint force design method allowing topology optimization for planar rigid-link and string mechanisms. To our best knowledge, by applying conventional machine and mechanism design theories, it is likely that it is possible to find out optimal locations of joints and lengths of rigid-links but somewhat difficult to find out optimal topology of rigid-links. To achieve optimal topology of rigid links, there is our previous contribution so called the new constraint force design method with the binary design variables determining the existence of the auxiliary forces imposing apparent lengths among unit masses. By adding new binary design variables, this research extends the constraint force design method to find out optimal mechanism consisting of stringy links as well as rigid links that seems impossible in the conventional machine and mechanism design theories.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.113-118
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• 1997

This paper presents the dimensional synthesis and kinematic analysis of the RSCS-SSP motion generating spatial mechanism using the displacement matrix method. This type of spatial mechanisms is used for the Mcpherson suspension in small automobiles. It is modeled for the wheel bump/rebound and steering motion. First, the suspension is modeled as a multiloop spatial rigid body guidance mechanism for the two major motions. Then the design equations for SSP, RS, and SC strut links are applied to synthesize an RSCS-SSP for up to three prescribed positions for the steering motiom from the suspension design specification. Thus a RSCS-SSP mechanism which is synthesized is also analyzed for the displacement during the steering motion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.464-466
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• 2014

The mechanism synthesis methods, graphical, analytical and computer-aided technique have been proposed for selecting and scaling mechanical system. According to developing computation tools, mechanism could be synthesized much faster and more correct than previous analytical ways by improved techniques. In this paper, the improved synthesis method is proposed to solve body guidance synthesis problem. To perform the mechanism synthesis for body guidance, a planar linkage is modeled as a set of free three bushings located in design space. The values of bushing stiffness and x, y position of bushings yielding a desired functional requirement related to input motion are found by using an optimization technique.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.1-7
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• 2006

The Green Wall system, developed in Austria early 1960, is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Green wall has pro-environmental advantages that able to grow grass in front space of stretchers and decrease cutting ground. In Europe, Green wall used without other reinforcement method. However, green wall used with other reinforcement method like a soil nailing because of environmental problem. This study was performed to introduce the design case by 'Two-Body Translation mechanism' to be able to consider distribution of earth pressure in the soil nailing when designing the green wall using soil nailing system. Also, this study attempts to evaluate the earth pressure change when advanced soil nailing system is constructed using $FLAC^{2D}$ ver. 3.30 program and 'Two-Body Translation mechanism'.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.89-94
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• 2010

The pretensioner is used to retract the belt webbing and tighten up any slack in the event of a crash. The retracting force of the pretensioner helps move the passenger into the optimum crash position in his or her seat. In this paper, the new concept of an operating mechanism of the pretensioning system is presented. The internal gear design program is developed using MATLAB. Two kinds of numerical analysis model are created. The first one, the rigid body dynamic model, is used to estimate the performance of several gear pairs. The initial performance of the new operating mechanism is analyzed and the best combination of the gear pairs is selected. The second one, the structural dynamic model, is used to calculate the deformation of the gear teeth. To decrease the deformation and interference of the teeth, the shape of the gear pairs is changed.