• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.105-112
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• 2013

This paper presents the structural design and finite element analysis of precision stage based on a double triangular parallel mechanism for precision positioning and large force generation. Recently, with the acceleration of miniaturization in mobile appliances, the demand for precision aligning and bonding has been increasing. Such processes require both high precision and large force generation, which are difficult to obtain simultaneously. This study aimed at constructing a precision stage that has high precision, long stroke, and large force generation. Actuators were tactically placed and flexure hinges were carefully designed by optimization process to constitute a parallel mechanism with a double triangular configuration. The three actuators in the inner triangle function as an in-plane positioner, whereas the three actuators in the outer triangle as an out-of-plane positioner. Finite element analysis is performed to validate load carrying performances of the developed precision stage.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.64.2-64
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• 2001

In this paper, fabricated is a motion capture and attitude detection system for Head Mounted Display HMD composed of three low-price and low-grade micro gyroscopes and a micro-controller, To calculate attitude of a body, modified INS algorithm is used. Because the micro gyroscope has much bias drift error, scale factor error, and run-to-run bias error, the motion of a body can not be measured exactly if the general INS algorithm and micro gyroscopes are used. To reduce the errors, three accelerometers can be used. In this case, however, the size and power consumption become too large to use in HMD system. The modified INS algorithm use the grid map and the characteristics of the human motions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.689-697
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• 1986

In the present work a three degree of freedom modeling of a cylindrical rubber element is studied and its applications to an engine mount system are discussed using a simple test structure. The three degree of freedom model for the rubber mount is composed of three mutually orthogonal springs and dampers jointed at the elastic center of the mount. The test structure is designed and manufactured so simple that its mass center and moment of inertia are accurately and easily obtained. The dynamic properties of each rubber mount, i.e., complex stiffnesses, are experimentally identified using hydraulic exciter and used to predict the modal parameters of the test structure mount system by analytical modal analysis. The predicted modal parameters of the system agree well with those estimated by experimental modal analysis. Hence the three DOF model of the rubber mount is proposed for the practical design of an engine mount system.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.120-131
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• 2020

In order to solve the problem of point clouds coordinate conversion of non-directional scanners, this paper proposes a basic Rodrigues rotation method. Specifically, we convert the 6 degree-of-freedom (6-DOF) rotation and translation matrix into the uniaxial rotation matrix, and establish the equation of objective vector conversion based on the basic Rodrigues rotation scheme. We demonstrate the applicability of the new method by using a bar-shaped emboss point clouds as experimental input, the three-axis error and three-term error as validate indicators. The results suggest that the new method does not need linearization and is suitable for optional rotation angle. Meanwhile, the new method achieves the seamless splicing of point clouds. Furthermore, the coordinate conversion scheme proposed in this paper performs superiority by comparing with the iterative closest point (ICP) conversion method. Therefore, the basic Rodrigues rotation method is not only regarded as a suitable tool to achieve the conversion of point clouds, but also provides certain reference and guidance for similar projects.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1178-1186
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• 2001

This paper presents design and analysis of a 6 degree-of-freedom new haptic device using a par-allel mechanism for interfacing with virtual reality. The mechanism is composed of three pantograph mecha-misms that, driven by ground-fixed servomotors. stand perpendicularly to the base plate. Three spherical joints connect the top of the pantograph with connecting bars, and three revolute joint connect connecting bars with a mobile joystick handle. Forward and inverse kinematic analyses have been performed and the Jacobian matrix is derived by using the screw theroy. Performance indices such as GPI(Global Payload Index), GCI(Global Conditioning index), Traslation and Orientation workspaces, and Sensitivity are evaluated to find optimal pa-rameters in the design stage. The proposed haptic mechanism has better load capability than those of the ex-isting haptic mechanisms due to the fact that motors are fixed at the base. It has also wider orientation work-space mainly due to RRR type spherical joints.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.288-293
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• 2010

This paper presents to calculate the lethality of missile for the simulation test program and to verify the simulation results. In order to calculate a reliable lethality we need may data and experiments of fuse and warhead, but in reality it is hard to perform a task. Therefore, this paper obtained from the reference paper to analyze the lethality data for the calculation of the lethality. We form the 6 DOF simulation model using the MATLAB/SIMULINK. And formed the autopilot algorithm using the vertical and horizontal acceleration feedback and PNG (Proportional Navigation Guidance) command be used to the guidance algorithm. Finally, we evaluate the results about three cases, front launch, side launch and rear launch to simulate the simulation program, and the target is designed to have a constant speed and direction.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.311-317
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• 2010

In the paper, we propose an improved mobility method of modular robots by physical docking in the uneven environments. The modular robot system consists of autonomous docking device, 3 DOF robotic arm, motion controller, and main controller. Real-time location and direction of the robot are estimated using inner GPS and they are used to control direction and path of each robot for physical docking between modular robots. We design a navigation algorithm of modular robot using physical docking and cooperative navigation in the environment with broken road and low stair. The proposed method is verified by navigation experiments of three developed modular robots in the uneven environments.

• Coupled systems mechanics
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• v.11 no.5
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• pp.439-458
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• 2022

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-Of-Freedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Coupled systems mechanics
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• v.12 no.6
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• pp.481-501
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• 2023

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-OfFreedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.162-167
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• 2018

The effect of the average particle size and shape of silver nanoparticles for the transparent conductive film (TCF) was studied. Optical and electrical properties of silver conductive lines coated on the polyethylene terephthalate (PET) film was also measured. Silver nanoparticles produced by Ag-CM, Ag-ME, Ag-EE methods showed an excellent conductivity compared to those produced by Ag-EB, Ag-CR and Ag-PL methods, but a little difference in the transparency. In the case of the former three silver nanoparticles, the average particle size was about 80 nm or less and the size was uniform. For the latter case, the severe agglomeration phenomena of particles was observed and the average particle size was 100 nm or more. This result was consistent with the result of the uniformity of the pattern shape and thickness on conductive line patterns observed by SEM. Therefore, it was confirmed that the electrical characteristics could be obtained when the average particle size of silver nanoparticles is smaller and the uniformity of the particles is maintained.