• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.393-396
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• 1996

This paper studies electrostatically suspended induction motors (ESIM). The ESIM possesses the rotating ability of an ordinary electrostatic induction motor, in addition to providing contactless support by electrostatic suspension. To accomplish these two functions, a feedback control strategy and the operating principle of an ordinary electrostatic induction motor are used. The stator possesses electrodes which exert the electrostatic forces to the rotor and are divided into a part responsible for suspension and one for rotation. Two rotor types are utilized: a polished glass disk without any surface treatment, and a polished glass disk covered with a thin layer of conductive material (ITO layer) on only one side. In this paper, the principle of the ESIM is described, followed by stator electrode design, experimental apparatus, control strategy for stable suspension. Experimental results show that the glass disk has been rotated with a speed of approximately 70 rpm while being suspended stably at a gap length of 0.3 mm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1125-1130
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• 2007

This paper presents a maneuver analysis of a full-vehicle featuring electrorheological (ER) suspension and ER brake. In order to achieve this goal, an ER damper and an ER valve pressure modulator are devised to construct ER suspension and ER brake systems, respectively. After formulating the governing equations of the ER damper and ER valve pressure modulator, they are designed and manufactured for a middle-sized passenger vehicle, and their field-dependent characteristics are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the governing equations of the ER suspension and ER brake. Subsequently, a sky-hook controller for the ER suspension and a sliding mode controller for the ER brake are formulated and implemented. Control performances such as vertical displacement and braking distance of vehicle are evaluated under various driving conditions through computer simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.295-298
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• 1996

In this paper, a self-tuning optimal control algorithm is proposed to retain the optimal performance of an active suspension system, when the vehicle has some time varying parameters and parameter uncertainties. We consider a 2 DOF time-varying quarter car model which has the parameter variation of sprung mass, suspension spring constant and suspension damping constant. Instead of solving algebraic riccati equation on line, we propose a neural network approach as an alternative. The optimal feedback gains obtained from the off line computation, according to parameter variations, are used as the neural network training data. When the active suspension system is on, the parameters are identified by the recursive least square method and the trained neural network controller designer finds the proper optimal feedback gains. The simulation results are represented and discussed.

• 동력기계공학회지
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• 제5권2호
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• pp.87-92
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• 2001

Automotive suspension system is a mechanism for isolation of the vibration coming from the road inputs. Recently, the electronically controlled suspension systems which may improve ride and handling performance have been developed. Here, the continuously controlled semi-active suspension system is focused. As a mechanism to control damping forces continuously, a solenoid valve is used. The modeling for the solenoid valve is introduced briefly, a vehicle dynamics modeling is constructed, and then combined system model is completed. To design the efficient control algorithm for the semiactive suspension system the knowledge based fuzzy logic is applied and the technique how to apply the sky-hook theory to the fuzzy logic is developed. Finally, to confirm the improvement of performance the computer simulation is carried out.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.917-922
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• 2007

Electromagnetic suspension, the suspension system used for Maglev trains, is now being applied to urban and inter-city transportation systems, offering environmental benefits. This suspension system is actively controlled to stabilize the suspended vehicle as it runs over an elevated guideway, which, for various reasons, may have deviations in its height. For this reason, frequency responses of the suspension to height deviations must be predicted in the system design cycle. The equations of motion of the electromagnetic suspension employing the 5 state feedback control law are derived for frequency analysis. The results of this paper could be used to determine design requirements for the urban Maglev transportation system currently under development in Korea.

• 산업기술연구
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• 제19권
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• pp.31-42
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• 1999

This paper presents a method for evaluating the performance of a leaf spring suspension and an air spring suspension systems for trucks in terms of ride and handling. Leaf springs, which generally have non-linear progressive force-deflection characteristics, are modeled using beam and contact elements. The leaf spring analysis model shows good correlation with experimental results. Each component of an air spring suspension system, which is a single leaf, air spring, height control valve, compressor and linkages, is modeled appropriately. Non-linear characteristics of air spring are accounted for using the measured data, and pressure and volume relations for height control system is also considered. The wheel rate of the air suspension is taken lower but roll stiffness is taken higher than those of leaf springs to improve ride and handling performance, which is verified through driving simulations.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.163-170
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• 2005

In this work, we propose a new type of HDD Load/unload (L/UL) suspension featuring shape memory alloy (SMA). The mechanical and thermal properties of the SMA film with respect to the material phase states are experimentally estimated and the SMA film is carefully integrated to the suspension. In order to obtain the desirable dynamic characteristics of the suspension during L/UL process, the design parameters of the SMA film such as geometric properties are determined by considering the vibration modes of the suspension related to the L/UL performance. After analyzing the modal characteristics of the proposed suspension, L/UL performance is evaluated through L/UL simulation by observing the vibration motion and minimum flying height of the slider during L/UL process.

• 동력기계공학회지
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• 제4권1호
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• pp.51-59
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• 2000

Active suspension systems have been using for improving ride quality and stability for vehicles. An active suspension system is composed of a hydraulic pump, pressure control valves, hydraulic dampers, vehicle body, tires and other components. In this study, the mathematical model for the active suspension system based on the quarter car concept is derived, and a program for analysing the dynamic behaviour of the suspension system is developed. The computed results by the developed program are compared with the experimental results for confirming the reliability and usefulness of the developed program.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.364-371
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• 2008

In general Maglev (magnetically levitated vehicle) has about 4 or 5 bogies per one vehicle to improve stability of electromagnetic suspension and 4 air-spring per one bogie are to be equipped to prevent form excessive yawing and pitching motion of bogie. 3 leveling valve per one vehcile will be applied to control the height of carbody. This kind of vehicle is on the design stage, and design review will be carried out before manufacture. The suspension system of Maglev consists of 16 of air-spring, auxiliray reservoir and orifice, 3 leveling valve, which are different composition comparative to conventional rolling stock. To improve operational reliability of vehicle, additional ventilation valve will be equipped with airspring. This kind of new design concept requires fundamental design review. In this study, suspension systems of Maglev will be built as mathematical model. Then designed suspension system will be reviewed in view of various points through proposed suspension simulation.

• Bulletin of the Korean Chemical Society
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• 제4권5호
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• pp.212-217
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• 1983

Depending on the range of shear rates, temperatures and concentrations, the potato starch suspension in water behaves as a typical dilatant system. The flow curves of the suspension at various concentrations and temperatures were obtained by using a Couette type rotational viscometer. The flow mechanism of the suspension is explained by a structure model of starch granules in the suspension. Based on the experimental results, a general flow equation for the dilatant system is proposed. By analyzing the temperature dependency of the relaxation time, the activation enthalpy and activation entropy for flow in the starch-water suspension were calculated, the former being about 10 kcal/mol.