• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.291-298
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• 2000

This paper describes a theoretical and experimental investigation into an active vibration isolation system in which four electromagnetic actuators are installed in parallel with each of four passive mounts placed between a piece of equipment and a vibrating base structure. Decentralised velocity feedback control is employed, where each actuator is operated independently by feeding back the absolute equipment velocity at the same location. Although one end of each actuator acts at the sensor positions on the equipment, the control system is not collocated because of the reactive forces acting on the flexible base structure, whose dynamics are strongly coupled with the mounted equipment. Isolation of low frequency vibration is considered where the equipment can be modelled as a rigid body and the mounts as lumped parameter springs and dampers. Control mechanisms are discussed, and some experimental and simulation results are reported.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.113-118
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• 1999

This paper presents a new approach to the design of neural control system using digital signal processors in order to improve the precision and robustness. Robotic manipulators have become increasingly important n the field of flexible automation. High speed and high-precision trajectory tracking are indispensable capabilities for their versatile application. The need to meet demanding control requirement in increasingly complex dynamical control systems under significant uncertainties, leads toward design of intelligent manipulation robots. The TMS320C31 is used in implementing real time neural control to provide an enhanced motion control for robotic manipulators. In this control scheme, the networks introduced are neural nets with dynamic neurons, whose dynamics are distributed over all the network nodes. The nets are trained by the distributed dynamic back propagation algorithm. The proposed neural network control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Performance of the neural controller is illustrated by simulation and experimental results for a SCARA robot.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.844-849
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• 2008

A nano-imprinting stage has been widely used in various fields of nano-technology. In this study, A 4-axis nano-imprinting stage is modeled with using the 3D-CAD Tool. Structural components such as an upper-plate, bearings and cross-roller-guides are modeled with finite elements to analyze flexibility effect during the precision stage motion. In addition, Dynamic analysis is executed to reproduce actual motion of 4-axis nano imprinting stage.

• Korea-Australia Rheology Journal
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• v.20 no.3
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• pp.143-152
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• 2008

Simulations of solutions of flexible polymer molecules during flow in simple or complex confined geometries are performed. Concentrations from ultradilute up to near the overlap concentration are considered. As concentration increases, the hydrodynamic migration effects observed in dilute solution unidirectional flows (Couette flow, Poiseuille flow) become less prominent, virtually vanishing as the overlap concentration is approached. In a grooved channel geometry, the groove is almost completely depleted of polymer chains at high Weissenberg number in the dilute limit, but at finite concentration this depletion effect is dramatically reduced. Only upon inclusion of hydrodynamic interactions can these phenomena be properly captured.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.42.1-42.1
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• 2011

NREL NWTC Deside codes are analyzed and introduced to develop the system performance simulation program for wind turbine generator systems. In this paper, The FAST performing multi-body and flexible body dynamics, control and the AeroDyn calculating aerodynamic forces with airfoil data and wind data are explained. Furthermore, initialization and process for transfer of aerodynamic force between AeroDyn and FAST at each time step are also introduced.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.950-953
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• 1988

The equations of motion for linearly elastic bodies undergoing large displacement motion are derived. This produces a set of equations which are efficient to numerically integrate. The equations for the elastic bodies are formulated and simplified to provide as much efficiency as possible in their numerical solution. A futher efficiency is obtained through the use of floating reference frame. The equation are presented in two forms for numerical integration. 1) Explicit numerical integration 2) Implicit numerical integration. In this paper, there was used the numerical integration. The implicit numerical integration is extended to solved second order equation, futher reducing the numerical effort required. The formulation given is seen to be occulate and is expected to be efficient for many types of problems.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.495-505
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• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.448-448
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• 2011

We investigated the fabrication method of superhydrophobic nanocoating prepared by a simple spin-coating and the chemisorption of fatty acid. The resulting coating showed a tremendous water repellency (static water contact angle = $154^{\circ}$) and the water contact angle can be modulated by changing the number of deposition cycles of ZnO and the carbon length of Self-Assembled Monolayers (SAM). Varying the number of deposition cycles of ZnO controlled the surface roughness, and affected to the superhydrophobicity. This simple coating method can be universally applicable to any substrates including flexible surfaces, papers and cotton fabrics, which can effectively be used in various potential applications. We also observed the thermal and dynamic stabilities of SAM on ZnO nanoparticles. The superhydrophobicic surface maintained its superhydrophobic properties below $250^{\circ}C$ and under dynamic conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.263-270
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• 1995

The use of the shape memory alloy, Nitinol wire, is investigated as an actuator for enhancing the damping in structural vibration systems. The first-order mathematical model of the Nitinol wire is obtained from the experimental data for an actuator. Finite element method is utilized for the strain gage sensor model, which is installed at the root of cantilever beam. A simple system, cantilever beam, is built as a flexible structural system to implement a control law with the Nitinol wire actuator. The system model including sensor and actuator is derived, which agrees with the experimental results. The actuator dynamics is augmented with the system so as to design PI controller and the one of robust controllers, LQG/LTR controller, and the control laws are implemented experimentally. The experimental study shows the feasibility of utilizing the Nitinol wire as an actuator for the purpose of vibration control.

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.29-29
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• 1996

The structure of an antimicrobial peptide buforin II has been studied by $^1$H NMR and CD spectroscopy. Buforin II is flexible and random structure in H$_2$O but the parts of buforin II become helical structure in trifluoroethanol (TFE)/H$_2$O (1:1, v/v) solution. From the restrained molecular dynamics calculation using NMR data, we obtained the possible conformation of buforin II in TFE/H$_2$O solution. (omitted)