• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.494-497
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• 2003

A rotating device driven by an Inchworm motor was designed and fabricated to be used as an angie standard system. 1. PZT was adopted as a driving source, while the movement of PZT was guided by the leaf spring employing the elastic transformation of metals. 2. The device could rotate in a 360-degree arc. continuously Performance test of the device showed about 0.02 sec. of the minimum revolution angle and 1/15 rpm of the maimum revolution speed. 3. To improve its performance requires further studies on realizing a shifting device with faster response time, on increasing the output current (capacity) of the power amplifier used to drive PZT, on the dynamic motion of clamping. and on determining the optimum clamping condition

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.703-709
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• 2002

In the present paper, approximate coordinate transformations for simulation of turbulent flows with wall deformation, significantly reducing computational cost with little degradation in numerical accuracy, are presented. The Wavier-Stokes equations are coordinate-transformed with an approximation of Tailor-series truncation. The performance is evaluated by performing numerical simulations of a channel flow at Re$\sub$$\tau$/ = 140 with active wall motions of η$\sub$m/$\^$+/ $\leq$5. The approximate transformations provide flow structures as well as turbulence statistics in good agreement with those from a complete transformation [Phys. Fluids 12, 3301 (2000) ] and allow 25-30% savings in the CPU time as compared to the complete one.

• Interaction and multiscale mechanics
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• v.2 no.4
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• pp.431-454
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• 2009

This paper presents a simple model for studying the dynamic response of multi-span bridges resting on piers with different heights and subjected to earthquake forces acting transversely to the bridge, but varying spatially along its length. The analysis is carried out using the modal superposition technique, while the solution of the resulting integral-differential equations is obtained via the Laplace transformation. It has been found that the piers' height and the quality of the foundation soil can affect significantly the dynamic behavior of such bridges. Typical examples showing the effectiveness of the method are presented with useful results listed.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.304-309
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• 1986

This paper is about the Inverse Jacobian for the TOP-1 robot. The robot Jacobian is used for the movement in accordance with differental changes. A Matrix and Homogeneous Transformation Matrix, Differential Motion Vector D are applied to Jacobian equation for the movement of the robot in accordance with the minut changes. The solution of Jacobian equation is acquired and applied for the subtle movement of each arms of the robot. The interface with APPLE-II Micro-computer is searched out too. The Software and the interface resulted from this paper are considered to be higly useful in the accurate control on the robot when they are linked with dynamics of robot.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1601-1608
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• 2000

This paper is concerned with the forced flexural vibration analysis of hard disk drive (HDD) spindle systems with multiple thin disks, supported by two ball bearings based on the finite element model. This is the extension of the previous work which analytically modeled every system component taking into account its structural flexibility and also the centrifugal stiffening effect especially for the disks. Among the end results, the forced time response is expectedly useful for the vibration control of the spindle itself or the position servo control of the magnetic head. On the other hand, the steady state responses such as the frequency response function and the unbalance response are useful for system identification. Futhermore, through a coordinate transformation the equations of motion is also derived with respect to the inertial frame for convenient analyses of certain classes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.127-132
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• 1992

To relize the future intelligent robot the development of a special-purpose processor for a coordinate transformation is evidently challenging task. In this case the complexity of a hardware architecture strongly depends on the adopted algorithm. In this paper we have used an inverse kinemetics algorithm based on incremental unit computation method. This method considers the 3-axis articulated robot as the combination of two types of a 2-axis robot: polar robot and 2-axis planar articulated one. For each robot incremental units in the joint and Cartesian spaces are defined. With this approach the calculation of the inverse Jacobian matrix can be realized through a simple combinational logic gate. Futhermore, the incremental computation of the DDA integrator can be used to solve the direct kinematics. We have also designed a hardware architecture to implement the proposed algorithm. The architecture consists of serveral simple unitsl. The operative unit comprises several basic operators and simple data path with a small bit-length. The hardware architecture is realized byusing the EPLD. For the straight-line motion of the KAIST arm we have obtained maximum end effector's speed of 12.6 m/sec by adopting system clock of 8 MHz.

• Smart Structures and Systems
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• v.26 no.2
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• pp.185-193
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• 2020

Nonlinear vibration of sandwich plate with functionally graded material (FGM) core and carbon nano tubes reinforced (CNTs) nano-composite layers by considering temperature-dependent material properties are studied in this paper. Base on Classical plate theory (CPT), the governing partial differential equations of motion for sandwich plate are derived using Hamilton principle. The Galerkin procedure and multiple scales perturbation method are used to find relation between nonlinear frequency and amplitude of vibration response. The dynamic responses of the sandwich plate are also investigated in both time and frequency domains. Then, the effects of nonlinearity, excitation, power law index of FG core, volume fraction of carbon nanotube, the function of material variations of FG core, temperature changes, scale transformation parameter and damping factor on the frequency responses are investigated.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.237-254
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• 2005

The vast mechanical systems could be classified as closed loop system, open loop system and open & closed (switching) system. In the closed loop system, the kinematics and dynamics of 3-D mechanisms will be reviewed and closed form solutions using the direction cosine matrix method and reflection transformation method will be introduced. In the open loop system, kinematic & dynamic analysis methods regarding the redundant system which has more degrees of freedom in joint space than those of task space are reviewed and discussed. Finally, switching system which changes its phase between closed and open loop motion is investigated with the principle of dynamical balance. Among switching systems, the human gait in biomechanics and humanoid in robotics are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1643-1649
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• 2000

When markers attached to body segment are captured by camera, they generally have many noises due to intrinsic biomechanical characteristics. In this study, one technique to reduce these noises is suggested, which constructs a local coordinates of the markers using time-mean lengths of the measured markers and calculates a linear transformation matrix of the interesting body using least square error technique. This matrix is decomposed into two matrices of rotation and flexibility. Suggested method does well for 3 markers or more, and shows consistent results without regard to choice of reference axis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.459-463
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• 1996

The lateral-shearing interferometer specially devised for production line inspection lenses is presented. The interferometer is composed with immersion oil and four prisms whose relative sliding motion provide lateral-shearing and phase-shifting. A special phase-measuring algorithm of a-bucket is adopted to compensate the phase-shifting error caused by the thickness reduction in the immersion oil Three different algorithm for determinating quantitative aberration of aspherical lenses are presented and compared with one another.