• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1729_1730
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• 2009

This paper presents comparative experimental results of PI sliding mode control and PI control for a heavy duty robot which can handle an object of 600kg, The gains of the PI control was determined by TAE(Trial and Error) method. This paper presents a novel approach for the decoupling of the states cross-coupling using sliding mode control. The sliding mode control methode is based on the error between reference speeds and the actual speed. The proposed method has the advantages of PI control performance and the sliding mode control robustness. Its first step is to design PI controller, then the sliding mode control input term is added to it. This makes actual implementation of the controller easier. The robot and motion controllers were designed and made by author. The good control performance of the heavy duty robot was obtained by using simple algorithm. This means that the robot was designed very well in control respect.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.30-36
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• 2004

We determined equivalent circuit parameters of a 1.5 cell S-band RF gun cavity from the resonant characteristics of its decoupled cavities(half cell and full cell) using the code SUPERFISH. Equivalent circuit parameters of the 1.5 cell RF gun cavity resonated in the 0-mode were obtained easily from the circuit parameters of each decoupled cavities. In order to obtain equivalent circuit parameters for the $\pi$ -mode cavity, we calculated the differences of the resonant frequencies and the equivalent resistances between the 0- and $\pi$ -modes with slight variations of the radius and thickness of the coupling iris. From those differences, we obtained R/Q value and equivalent resistance of the $\pi$ -mode, which are directly related to the equivalent circuit parameters of the coupled cavity. Using calculated R/Q value, we can express equivalent inductance, capacitance and resistances of the RF gun cavity resonated in the $\pi$ -mode, which can be useful for analyzing coupled cavities in a steady state.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1225-1227
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• 1992

This paper presents a study on the variable structure PI(proportional and integrate) control which is insensible to the variation of parameters or external disturbance for driving DC motor. In the presented variable structure PI control (VSPIC), the sliding mode control was used at the below of 4000 rpm and PI control also used at the above of 4000 rpm with no load. In other way, the PI control was used at the below of 4000 rpm and the sliding mode control at the above of 4000 rpm with some loading, and then the output waveform following the variation of load was measured. intel 8031 microcomputer unit and IBM PC was combined to form the full system and the speed control was performed with it. The experimental result of the fast response to speed was more improve than it was open loop state. For load varing, the sliding mode insensible to external disturbance was applied and the improved response was obtained.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.34-37
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• 2001

In this paper the comparison of conventional PI control and nonlinear sliding mode control is presented for Switched Reluctance Motor(SRM). SRM drives require a nonlinear controller for high dynamic Performance but the high nonlinearity makes a poor performance in conventional PI control. However SRMs with sliding mode control achieve a robust performance for speed control. In this paper nonlinear sliding mode controller is suggested for high performance speed. State equation and modeling are proposed. And we present the speed comparison of PI control and SLMC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.53-56
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• 2003

Blending effects for generating a pretilt angle in nematic liquid crystal (NLC) with negative dielectric anisotropy on the blended polyimide (PI) of homeotropic and homogeneous alignment surface were studied. Also, we investigated the EO performances for the advanced VA-$\pi$ cell using this homeotropic blended PI surface. A many decrease of tilt angle on the polymer surface to blend homeotropic PI and homogeneous PI with side chain type was measured, and the tilt angle decreased as blended ratio and rubbing strength increase. The blended effects for generating a pretilt angle were clearly observed, and the many decrease of tilt angle can be achieved by using the blended PI surface. The electro-optical (EO) characteristics using the advanced VA-$\pi$ cell using the homeotropic blended PI surface than that of conventional VA cell can be improved. We suggest that the developed advanced VA-$\pi$ cell on a homeotropic blended PI surface is a promising technique for the achievement of a fast response time, and a high contrast ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.710-719
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• 2008

In this paper, a transmission technique of paging indicator (PI) on the existing preamble is proposed to reduce power consumption of the user equipment in idle mode for OFDM-based cellular systems. Compared with the PI transmission technique using the L1/L2 control channel, the PI transmission technique using preamble has advantages of not requiring additional overhead for PI transmission as well as reducing computational complexity for PI detection. Synchronization and PI detection techniques are descried for OFDM-based cellular systems, especially for mobile WiMAX systems. It is shown by computer simulation that the PI can be transmitted using the preamble (or common synch symbol) without affecting performances of synchronization and cell searching in mobile WiMAX systems.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.398-398
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• 2010

To determine the molecular directionality of PI chains depending on rubbing condition, we measured the angle resolved near edge X-ray absorption fine structure (NEXAFS) spectra at C K-edge of the rubbed PI films. Twisted nematic mode PI (PI-TN) and in plane switching mode PI (PI-IPS) were introduced to examine the effect of rubbing conditions on the chain directionality. The average tilt angle a of the PI molecules was estimated through the measured intensity change of $C=C\;{\pi}^*$ in NEXAFS C K-edge spectrum by controlling the stage speed and the pile contact depth. After rubbing, the irregular molecular direction changed to a regular direction with a molecular tilt angle of $51.2^{\circ}$ for PI-TN and $49.6^{\circ}$ for PI-IPS at the rubbing condition of the roll speed of 1000 rpm, stage speed of 50 mm/sec, and file contact depth of 0.3 mm. The molecular tilt angle $\alpha$ was linearly decreased in the PI-TN and PI-IPS samples with increasing depth of the pile contact.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.616-623
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• 2003

Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the quality of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, acceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically performed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.176-178
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• 2006

This paper is intended to research the speed response of switched reluctance motor (SRM) using sliding mode control method when load is changing. The simulation compare only control by PI controller with control by PI controller and sliding mode controller. It compare with speed response using MATLAB/SIMULINK.

• Journal of Power Electronics
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• v.18 no.3
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• pp.766-777
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• 2018

In this paper, a sliding mode and proportional plus integral (SM-PI) control combined with self-sustained phase shift modulation (SSPSM) for LLC resonant converters is presented. The proposed control scheme improves the transient response while preserving good steady-state performance. An averaged large signal model of an LLC converter with the ZVS modulation technique is developed for the SM control design. The sliding surface is obtained based on the input-output linearization concept. A system identification method is adopted to obtain the transform function of the LLC resonant converter, which is used to design the PI control. In order to reduce the inherent chattering problem in the steady state, the combined SM-PI control strategy is derived with fuzzy control, where the SM control is responsive during the transient state while the PI control prevails in the steady state. The combination of SSPSM and the SM-PI control provides ZVS operation, robustness and a fast transient response against step load variations. Simulation and experimental results validate the theoretical analysis and the attractive features of the proposed scheme.