• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.15-22
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• 1999

This paper demonstrates the feasibility of Shape Memory Alloy (SMA) actuators in controlling the motion of micro active catheter. The dynamic behavior of SMA is obtained by several experiments for the design of the controller. With the control parameters obtained in experiments, temperature feedback control algorithm is proposed and realized. The prototype of micro active catheter is fabricated, and its control performance which uses the designed controller is investigated. The results obtained show the potential of the SMA as viable means for actuating the micro active catheter.

• Structural Engineering and Mechanics
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• v.49 no.3
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• pp.329-353
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• 2014

Increasing usage of tank cars and their intrinsic instability due to sloshing of contents have caused growing maintenance costs as well as more frequent hazards and defects like derailment and fatigue of bogies and axels. Therefore, varieties of passive solutions have been represented to improve dynamical parameters. In this task, assuming 22 degrees of freedom, dynamic analysis of partially filled tank car traveling on a curved track is investigated. In order to consider stochastic geometry of track; irregularities have been derived randomly by Mont Carlo method. More over the fluid tank model with 1 degree of freedom is also presented by equivalent mechanical approach in terms of pendulum. An active suspension system for described car is designed by using linear quadratic optimal control theory to decrease destructive effects of fluid sloshing. Eventually, the performance of the active suspension system has been compared with that of the passive one and a study is carried out on how active suspension may affect the dynamical parameters such as displacements and Nadal's derailment index.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.13-19
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• 2011

In this paper, the active monitoring and control system is developed. This system can monitor the status of high the speed spindle in real time during its processing, and can analyze its influence of dimensional accuracy and processing if any, and can control the machining condition to realize the machining system equipped with active monitoring and self-diagnostic features. Machining experiment was performed on 3 materials Al, Brass and S45C in order to derive the relation between active monitoring and control algorithm by the machining load. In addition, we measured surface roughness of processing specimen along with the data change of spindle rotating speed and conveying speed according to variation of machining load. Based on these experiments, we derived relations for each material that can be applied to the control algorithm to allow self control of the rotating speed and conveying speed according to the machining load.

• Current Optics and Photonics
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• v.1 no.3
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• pp.239-246
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• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.937-941
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• 2004

Since semi-active suspension systems of automobile, of which suspension damper are controlled actively, exhibit high performance with light system weight, low cost and low energy consumption. From this view point, semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspension systems. In this Paper, mathematical modeling and dynamic characteristics analysis of a reverse continuously variable damper and valve used for semi-active suspension systems are investigated. The mathematical model of piston with valve are proposed by IMAGINE/AMESim in the paper. To verify the mathematical model developed, the dynamic characteristics are simulated by IMAGINE/AMESim and are compared with experimental results. It was confirmed that the developed models represent well the actual system and can be used for control system design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2179-2186
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• 1997

In this paper, the performance of a semi-active suspension system for a passenger car has been investigated. Alternative semi-active suspensions control laws has been compared via simulations. The control laws investigated in this study are : sprung mass velocity feedback control law, sky-hook damping control law, and state feedback control law. Simulation results show that a semi-active suspension has potential to improve ride quality of automobiles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.660-664
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• 2003

The optimal thickness distribution of an active damping layer is sought so that it satisfies a certain constraint on the dynamic performance of a system minimizing control efforts. To obtain a topologically optimized configuration, which includes size and shape optimization, thickness of the active damping layer is interpolated using linear functions. With the control energy as the objective function to be minimized, the state error energy is introduced as the dynamic performance criterion for the system and used lot a constraint. The optimal control gains are evaluated from LQR simultaneously as the optimization of the layer position proceeds. From numerical simulation, the topologically optimized distribution of the active damping layer shows the same dynamic performance and cost as the Idly covered counterpart, which is optimized only in terms of control gains, with less amount of the layer.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.50 no.3
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• pp.130-137
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• 2001

In this paper, we propose a new Active Noise Filter Control System which operate as a control performance when a adaptive filter fault. In this system, half-fixed filter which is new filter, connected to parallel with adaptive filter. An adaptive filler use to continuous parameter estimating, but adaptive filter is fault, half-fixed filter update newly data which is continuous estimating date each during sampling period. We simulate and apply the proposed active noise filter system to in the cylinder type duct. Experimental results show that proposed Active Noise Filter Control System has better control performance than existing filter which Eriksson's or Parallel Filter System in term of noise reduction.

• Journal of Industrial Technology
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• v.18
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• pp.317-322
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• 1998

The purpose of this present experiments was to simulate the Active noise control system using MATLAB Tool kit. The Least-Mean-Square algorithm is the most applicable one to optimize the ANC systems, even it has tight limitation. This paper shows the influence of choosing step size to the performance of the LMS adaptive filters. In addition to the simulation, this paper describes the method to design the filtered LMS algorithm to get the better performance in Active noise control. It contains the secondary-path modeling to realize the real Active noise control system in the requesting fields.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.8
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• pp.517-524
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• 2004

In this paper, a novel zero-voltage-switching(ZVS) resonant DC-DC converter is proposed. It is composed of two symmetrical active-clamped circuits, the converter can be achieve ZVS in each switches. Also, active clamp capacitor ratios($\alpha$) of proposed circuit can be reduce a peak stress of switching voltage for each main switch. Simulation results using Pspice 9.2 ver and $C^{++}$ characteristic analysis show a provement for the validity of theoretical analysis. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and achieved an evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.