• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2665-2671
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• 2000

Dimensional Synthesis, which is apart of kinematic synthesis, is to determine the dimensions of a mechanism of preconceived typer for a specified task and prescribed performance. In this paper, in an effort to provide designers with flexibility, a dimensional approximate synthesis method is presented for utilizing prescribed tolerance both the displacement and joint positions of a mechanism to be synthesized. For this, a constrained optimization problem is formulated with displacement parameters and joint positions as variables. The proposed method is applied to the synthesis of a 5-SS multi link suspension mechanism. The method discussed here, however, can be easily applied to any mechanism of which the kinematic constraint equations can be derived.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.477-480
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• 2016

Based on the Jansen mechanism theory, a walking robot is developed, which is able to overcome the given obstacles. Taking joint positions and leg directions as design parameters, the walking robot is analyzed. In order to analyze and optimize the leg motion, Edison program and Jansen mechanism optimization solver are used, respectively. It is found that Edison program is so effective to determine joint variables and position of leg direction. With the help of these programs, lots of trials or errors could be saved.

• The Journal of Korea Robotics Society
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• v.12 no.2
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• pp.194-205
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• 2017

A redundantly actuated planar 3-degree-of-freedom parallel mechanism is analyzed to show its high application potential as a haptic device. Its structure along with the closed form forward position solutions is briefly discussed. Then its geometric and kinematic characteristics via singularity analysis, the kinematic isotropy index, and the input-output force transmission ratio are investigated both for the redundantly actuated cases and for the non-redundantly actuated case. In addition, comparative joint torque simulations of the mechanism with different number of redundant actuations as well as without redundant actuation are conducted to confirm the improved joint torque distribution characteristics. Through these analyses it is shown that the geometric and kinematic characteristics of the redundantly actuated mechanism are superior to the ones of the mechanism without redundant actuation. Thus, it can be concluded that the suggested planar mechanism with redundant actuation has a very high potential for haptic device applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.355-360
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• 2002

To calibrate a non-redundantly actuated parallel mechanism, one can find actual kinematic parameters by means of geometrical constraint of the mechanism's kinematic structure and measurement values. However, the calibration algorithm for a non-redundant case does not apply fur a redundantly actuated parallel mechanism, because the angle error of the actuating joint varies with position and the geometrical constraint fails to be consistent. Such change of joint angle error comes from constraint torque variation with each kinematic pose (meaning position and orientation). To calibrate a redundant parallel mechanism, one therefore has to consider constraint torque equilibrium and the relationship of constraint torque to torsional deflection, in addition to geometric constraint. In this paper, we develop the calibration algorithm fir a redundantly actuated parallel mechanism using these three relationships, and formulate cost functions for an optimization algorithm. As a case study, we executed the calibration of a 2-DOF parallel mechanism using the developed algorithm. Coordinate values of tool plate were measured using a laser ball bar and the actual kinematic parameters were identified with a new cost function of the optimization algorithm. Experimental results showed that the accuracy of the tool plate improved by 82% after kinematic calibration in a redundant actuation case.

• Geomechanics and Engineering
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• v.13 no.4
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• pp.535-570
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• 2017

There are only few cases where cause and location of failure of a rock structure are limited to a single discontinuity. Usually several discontinuities of limited size interact and eventually form a combined shear plane where failure takes place. So, besides the discontinuities, the regions between adjacent discontinuities, which consist of strong rock and are called material or rock bridges, are of utmost importance for the shear strength of the compound failure plane. Shear behaviour of persistent and non-persistent joint are different from each other. Shear strength of rock mass containing non-persistent joints is highly affected by mechanical behavior and geometrical configuration of non-persistent joints located in a rock mass. Therefore investigation is essential to study the fundamental failures occurring in a rock bridge, for assessing anticipated and actual performances of the structures built on or in rock masses. The purpose of this review paper is to present techniques, progresses and the likely future development directions in experimental testing of non-persistent joint failure behaviour. Experimental results showed that the presence of rock bridges in not fully persistent natural discontinuity sets is a significant factor affecting the stability of rock structures. Compared with intact rocks, jointed rock masses are usually weaker, more deformable and highly anisotropic, depending upon the mechanical properties of each joint and the explicit joint positions. The joint spacing, joint persistency, number of rock joint, angle of rock joint, length of rock bridge, angle of rock bridge, normal load, scale effect and material mixture have important effect on the failure mechanism of a rock bridge.

• Computers and Concrete
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• v.27 no.2
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• pp.99-109
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• 2021

Experimental and discrete element methods were used to investigate the effects of echelon non-persistent joint on the failure behaviour of joint's bridge area under uniaxial compressive test. Concrete samples with dimension of 150 mm×100 mm×50 mm were prepared. Uniaxial compressive strength and tensile strength of concrete were 14 MPa and 1MPa, respectivly. Within the specimen, three echelon non-persistent notches were provided. These joints were distributed on the three diagonal plane. the angle of diagonal plane related to horizontal axis were 15°, 30° and 45°. The angle of joints related to diagonal plane were 30°, 45°, 60°. Totally, 9 different configuration systems were prepared for non-persistent joint. In these configurations, the length of joints were taken as 2 cm. Similar to those for joints configuration systems in the experimental tests, 9 models with different echelon non-persistent joint were prepared in numerical model. The axial load was applied to the model by rate of 0.05 mm/min. the results show that the failure process was mostly governed by both of the non-persistent joint angle and diagonal plane angle. The compressive strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the shear behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint angle. The strength of samples increase by increasing both of the joint angle and diagonal plane angle. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.

• Journal of TMJ Balancing Medicine
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• v.12 no.1
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• pp.1-6
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• 2022

Objectives: For the deviation phenomenon occurring during the treatment process in temporo-mandibular balancing medicine (TBM), hypotheses were established regarding the cause and mechanism of formation from the perspective of neuro-science and material mechanics, and a verification method was proposed. Methods: The deviation phenomenon was theoretically analyzed based on the structure theories of material mechanics of the joint and the neurological pain mechanism. Results: Deviation occurs due to temporary yield by the accumulation of heterogeneous stress in the temporo-mandibular joint and the affected joint. Because the joint structures are corresponding with material mechanics showing compressive and tensile properties. The size of the deviation is expressed in terms of strain. The occlusal surface of the teeth is level with the axial joint. Since the magnitude of the deviation has a proportional relationship with the degree of abnormality of the temporo-mandibular joint, the magnitude of the deviation calculated by the balance measurement can be replaced by the strain. The major variables involved in the occurrence of deviations are the strength of joint structures and neurological conditions. Therefore plastic deformation and adaptation occur as a long-term depression of neural circuits is strengthened in different ways at different locations each time in various clinical situations. This is the reason why the sequence of the restoration process while correcting deviations is following reverse order of the accumulation in many layers in the muscular nervous system. Conclusions: From the above results, it can be inferred that the occurrence and correction of the deviations are corresponding with the plastic deformation and neuro-plasticity.

• IE interfaces
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• v.2 no.2
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• pp.25-32
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• 1989

We study the joint cost allocation based on the book profit producing power of the output through the A-S price mechanism. We show what part of the A-S book profit is allocated to the joint cost and what part is allocated to the variable total book profit of the short-run book profit function. Also we compare some other classical joint cost allocation methods with this A-S price method.

• Structural Engineering and Mechanics
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• v.56 no.1
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• pp.67-83
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• 2015

The load transfer mechanism and load-bearing capacity of cast steel joints for H-shaped beam to square tube column connection are studied based on the deformation compatibility theory. Then the monotonic tensile experiments are conducted for 12 specimens about the cast steel joints for H-shaped beam to square tube column connection. The findings are that the tensile bearing capacity of the cast steel joints for beam-column connection depends on the ring of cast steel stiffener. The tensile fracture happens at the ring of the cast steel stiffener when the joint fails. The thickness of square tube column has little influence on the bearing capacity of the joint. The square tube column buckles while the joint without concrete filled, but the strength failure happens for the joint with concrete filled column. And the length of welding connection between square tube column and cast steel stiffener has little influence on the load-bearing capacity of the cast steel joint. Finally it is shown that the load-bearing capacity of the joints for H-shaped beam to concrete filled square tube column connection is larger than that of the joints for H-shaped beam to square tube column connection by 10% to 15%.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.4
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• pp.19-30
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• 2002

The stability of slope using root-pile like to the reinforcements is affected by the interaction behavior mechanism of soil-reinforcements. Through the studying on the interaction in joint of its, therefore, the control roles can be find out in installed slope. In study, the stress level ratio based on the insert angle of installed reinforcements in soil used to numerical analysis, which was results from the duty direct shear test in Lab. The maximum shear strain variation on the reinforcements was observed at insert angle, which was approximately similar to the calculated angle based on the equation proposed by the Jewell. The elasto-plastic joint model on the contact area of soil-reinforcements was presumed, the reinforced soil assumed non-linear elastic model and the reinforcements supposed elastic model, respectively. The finite element analysis of assumed models was performed. The shear strain variation of non-reinforced state obtained by the FEM analysis including elasto-plastic joint elements were shown the rationality of general limit equilibrium analysis for the slope failure mode on driving zone and resistance zone, which based on the stress level step according to failure ratio. Through the variation of shear strain for the variation of inserting angle of reinforcements, the different mechanism on the bending and the shear resistance of reinforcements was shown fair possibility.