• Proceedings of the KSME Conference
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• 2007.05a
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• pp.861-866
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• 2007

This paper presents development of a vehicle lateral and longitudinal control for autonomous driving control and test results obtained using an electric vehicle. Sliding control theory has been used to develop a vehicle speed and distance control algorithm. The longitudinal control algorithm that maintains safety and comfort of the vehicle consists of a cruise and STOP&GO control depending on traffic conditions. Desired steering angle is determined through the lateral position error and the yaw angle error based on preview optimal control. Motor control inputs have been directly derived from the sliding control law. The performance of the autonomous driving control which is integrated with a lateral and longitudinal control is investigated by computer simulations and driving test using an electric vehicle. Electric vehicle system consists of DC driving motor, an electric power steering system, main controller (Autobox)

• Journal of Drive and Control
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• v.14 no.3
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• pp.18-24
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• 2017

The purpose of this paper is to develop a new submersible fish cage operated by a pneumatic system for offshore aquaculture. Although some researchers have investigated modeling and control of fish cages, such cages consist of variable ballast tanks that with closed cylinders and thus present a maintenance issue. In solving the issue the new submersible fish cage investigated consists of bottom-opening cylinders. Accordingly, we designed a mathematical model of the concept and applied Sliding Mode Control for nonlinear angle control. Some experiments conducted under assumed conditions indicate that the angle of the system converges to zero under all conditions and the control has the stability to balance the fish cage.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.526-529
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• 1998

In this paper, we proposed a nonlinear sliding mode controller to regulate the swinging angle of Overhead Crane System. Roughly speaking, the controller is designed to regulate an output(the swing angle) while providing internal stability. It is difficult to apply many of standard nonlinear control design techniques. In contrast to control that use a command generator and possibly a time-varying feedback, our control law is simple autonomous nonlinear controller. We analyze the stability of the closed-loop system using an $L_2$ Sliding surface conditions approach on a nonlinear feedback linearization of the system about the desired periodic orbit. One can easily extend this approach to analyze the robustness of the control system with respect to disturbances and parameter variations.

• Korean Journal of Materials Research
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• v.22 no.8
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• pp.416-420
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• 2012

Recently nanoscience and nanotechnology have been studied intensively, and many plants, insects, and animals in nature have been found to have nanostructures in their bodies. Among them, lotus leaves have a unique nanostructure and microstructure in combination and show superhydrophobicity and a self-cleaning function to wipe and clean impurities on their surfaces. Coating films with combined nanostructures and microstructures resembling those of lotus leaves may also have superhydrophobicity and self-cleaning functions; as a result, they could be used in various applications, such as in outfits, tents, building walls, or exterior surfaces of transportation vehicles like cars, ships, or airplanes. In this study, coating films were prepared by dip coating method using polypropylene polymers dissolved in a mixture of solvent, xylene and non-solvent, methylethylketon, and ethanol. Additionally, attempts were made to prepare nanostructures on top of microstructures by coating with the same coating solution with an addition of carbon nanotubes, or by applying a carbon nanotube over-coat on polymer coating films. Coating films prepared without carbon nanotubes were found to have superhydrophobicity, with a water contact angle of $152^{\circ}$ and sliding angle less than $2^{\circ}$. Coating films prepared with carbon nanotubes were also found to have a similar degree of superhydrophobicity, with a water contact angle of 150 degrees and a sliding angle of 3 degrees.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.495-500
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• 2013

This paper proposes a double sliding surfaces based on a sliding mode control for a tracking control of nonholonomic mobile robots in the Cartesian coordinates. In order to remove sliding surface constraints, we design the additional sliding surface for the heading angle with respect to the newly defined coordinates. Then, we define the switching law based on the posture error to combine the designed sliding surface with the previous one. By using the double sliding surfaces and the switching law, we obtain the control law for arbitrary trajectories. It is proved that the position tracking error and the heading direction error asymptotically converge to zero, respectively, with the Lyapunov stability theory. Finally, through computer simulations, we demonstrate the effectiveness of the proposed control system.

• Journal of Power Electronics
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• v.10 no.4
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• pp.412-418
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• 2010

This paper proposes a new algorithm to generate a reference signal for an active power filter using a sliding-window FFT operation to improve the steady-state performance of the active power filter. In the proposed algorithm the sliding-window FFT operation is applied to the load current to generate the reference value for the compensating current. The magnitude and phase-angle for each order of harmonics are respectively averaged for 14 periods. Furthermore, the phase-angle delay for each order of harmonics passing through the controller is corrected in advance to improve the compensation performance. The steady-state and transient performance of the proposed algorithm was verified through computer simulations and experimental work with a hardware prototype. A single-phase active power filter with the proposed algorithm can offer a reduction in THD from 75% to 4% when it is applied to a non-linear load composed of a diode bridge and a RC circuit. The active power filter with the proposed reference generation method shows accurate harmonic compensation performance compared with previously developed methods, in which the THD of source current is higher than 5%.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1156-1158
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• 1997

This paper presents the proposed full-order observer-based sliding mode power system stabilizer(FOOSMPSS) for finding unmeasurable state variables(torque angle, quadratic-axis transient voltage, exciter output voltage, voltage regulator output voltage and output voltage) by measuring angular velocity. The simulation results is shown by the comparison of the FOOPSS with the proposed FOOSMPSS.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.299-308
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• 2007

This study proposes a two-layer hierarchical control system that integrates active front wheel steering and four wheel braking torque control to improve vehicle handling performance and stability. The first layer is a robust model matching controller (R-MMC) based on linear matrix inequalities (LMIs), which optimizes an active front steering angle compensation and a desired yaw moment control, and calculates reference wheel slip for the target wheel according to the desired yaw moment. The second layer is a moving sliding mode controller (MSMC) that can track the reference wheel slip in a predetermined time by commanding proper braking torque on the target wheel to achieve the desired yaw moment. Since vehicle sideslip angle measurement is difficult to achieve in practice, a sliding mode observer (SMO) that requires only vehicle yaw rate as the measured input is also developed in this study. The performance and robustness of the SMO and the integrated control system are demonstrated through comprehensive computer simulations. Simulation results reveal the satisfactory tracking ability of the SMO, and the superior improved vehicle handling performance, stability and robustness of the integrated control vehicle.

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.247-267
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• 2012

Calculating the displacements of retaining walls under seismic loads is a crucial part in optimum design of these structures and unfortunately the techniques based on active seismic pressure are not sufficient alone for an appropriate design of the wall. Using limit analysis concepts, the seismic displacements of retaining walls are studied in present research. In this regard, applying limit analysis method and upper bound theorem, a new procedure is proposed for calculating the yield acceleration, critical angle of failure wedge, and permanent displacements of retaining walls in seismic conditions for two failure mechanisms, namely sliding and sliding-rotational modes. Also, the effect of internal friction angle of soil, the friction angle between wall and soil, maximum acceleration of the earthquake and height of the wall all in the magnitude of seismic displacements has been investigated by the suggested method. Two sets of ground acceleration records related to near-field and far-field domains are employed in analyses and eventually the results obtained from the suggested method are compared with those from other techniques.

• Computers and Concrete
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• v.26 no.6
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• pp.483-495
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• 2020

Dams are vital infrastructures that are expected to maintain their stability during seismic excitations. Accordingly, cemented material dams are an emerging type, which are being increasingly used around the world owing to benefiting from advantages of both earth-fill and concrete gravity dams, which should be designed safely when subjected to strong ground motion. In the present paper, the seismic performance of a cemented sand and gravel (CSG) dam is assessed using incremental dynamic analysis (IDA) method by accounting for two failure modes of tension cracking and base joint sliding considering the dam-reservoir-foundation interactions. To take the seismic uncertainties into account, the dam is analyzed under a suite of ground motion records and then, the effect of friction angle for base sliding as well as deformability of the foundation are investigated on the response of dam. To carry out the analyses, the Cindere dam in Turkey is selected as a case study, and various limit states corresponding to seismic performance levels of the dam are determined aiming to estimate the seismic fragilities. Based on the results, sliding of the Cindere dam could be serious under the maximum credible earthquake (MCE). Besides, dam faces are mostly to be cracked under such level of intensity. Moreover, the results indicate that as friction angle increases, probability of sliding between dam and foundation is reduced whereas, increases tensile cracking. Lastly, it is observed that foundation stiffening increases the probability of dam sliding but, reduces the tensile damage in the dam body.