• Geomechanics and Engineering
• /
• 제12권2호
• /
• pp.239-255
• /
• 2017

Various centrifuge model tests on the pile foundations were performed to investigate fundamental characteristics of a pile-soil-foundation system recently, but it is hard to find numerical analysis results of a pile foundation system considering the nonlinear behavior of soil layers due to the dynamic excitations. Numerical analyses for a pile-soil system were carried out to verify the experimental results of centrifuge model tests. Centrifuge model tests were performed at the laboratory applying 1.5 Hz sinusoidal base input motions, and nonlinear numerical analyses were performed utilizing a finite element program of P3DASS in the frequency domain and applying the same input motions with the intensities of 0.05 g~0.38 g. Nonlinear soil properties of soil elements were defined by Ramberg-Osgood soil model for the nonlinear dynamic analyses. Nonlinear numerical analyses with the P3DASS program were helpful to predict the trend of experimental responses of a centrifuge model efficiently, even though there were some difficulties in processing analytical results and to find out unintended deficits in measured experimental data. Also nonlinear soil properties of elements in the system can be estimated adequately using an analytical program to compare them with experimental results.

• 전기학회논문지
• /
• 제60권7호
• /
• pp.1417-1426
• /
• 2011

Radiofrequency ablation through cardiac catheterization is one of minimally invasive intervention procedures used in drug resistant arrhythmia treatment. To facilitate more accurate and precise catheter navigation, systems for robotic cardiac catheter navigation have been developed and commercialized. The authors have been developing a novel robotic catheter navigation system. The system is a network-based master-slave configuration 3-DOF (Degree-Of-Freedom) robotic manipulator for operation with conventional cardiac ablation catheter. The catheter manipulation motion is composed of the translation (forward/backward) and the roll movements of the catheter and knob rotation for the catheter tip articulation. The master manipulator comprises an operator handle compartment for the knob and the roll movement input, and a base platform for the translation movement input. The slave manipulator implements a robotic catheter platform in which conventional cardiac catheter is mounted and the 3-DOF motions of the catheter are controlled. The system software that runs on a realtime OS based PC, implements the master-slave motion synchronization control in the robot system. The master-slave motion synchronization performance tested with step, sinusoidal and arbitrarily varying motion commands showed satisfactory results with acceptable level of steady state error. The developed system will be further improved through evaluation of safety and performance in in vitro and in vivo tests.