• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.327-338
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• 2008

A fault tolerant control system design technique has been proposed and analyzed for managing performance degradation in the presence of multiple faults in actuators. The method is based on a control structure with a model reference reconfigurable control design in an inner loop and command input adjustment in an outer loop. The reduced dynamic performance requirements in the presence of different actuator faults are accounted for through different performance reduced (degraded) reference models. The degraded steady-state performances are governed by the reduced levels of command input. The reconfigurable controller is designed on-line automatically in an explicit model reference control framework so that the dynamics of the closed-loop system follow that of the performance reduced reference model under each fault condition. The reduced command input level is determined to prevent potential actuator saturation. The proposed method has been evaluated and analyzed using an aircraft example against actuator faults subject to constraints on the magnitude and slew-rate of actuators.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.657-658
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• 2005

We designed 10bit source driver LSI, then the high color depth and the low power consumption are realized thru it. It is adopted mini-LVDS receiver with high speed data transmission and good data recovery performance, Hybrid type DAC to reduce decoder size and OP-AMP with low power consumption and high slew rate. In addition we show our results of the 10-bit gray scale TFT-LCD source driver for 42inch diagonal size and WXGA resolution TFT-LCD TV applications.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2032-2034
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• 2000

The performance of ac plasma display panels (PDP) is influenced strongly by the surface glow discharge characteristics on the MgO thin films. This paper deals with the surface slew discharge characteristics and some physical properties of MgO thin films prepared by reactive RF planar unbalanced magnetron sputtering in connection with ac PDP. The samples prepared with the do bias voltage of -10V showed lower discharge voltage and lower erosion rate by ion bombardment than those samples prepared by conventional magnetron sputtering or E-beam evaporation. The main factor that improves the discharge characteristics by bias voltage is considered to be due to the morphology changes or crystal structure of the MgO thin film by ion bombardment during deposition process.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.341-342
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• 2007

The IRFPA (InfraRed Focal Plane Array) ROIC (ReadOut Integrated Circuit) was designed in folded-cascode Op-Amp using $0.35{\mu}m$ CMOS technology. As the folded-cascode has high open-loop voltage gain and fast settling time, that used in many analog circuit designs. In this paper, folded-cascode Op-Amp for ROIC of the $32{\times}32$ IRFPA has been designed. HSPICE simulation results are unit gain bandwidth of 13.0MHz, 90.6 dB open loop gain, 8 V/${\mu}m$ slew rate, 600 ns settling time and $66^{\circ}$ phase margin.

• Journal of IKEEE
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• v.20 no.1
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• pp.103-106
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• 2016

PWM buck converters usually use a type-III error amplifier. Since this amplifier has a big capacitor with slow slew rate, they can generate an unintended large overshoot/undershoot at the output when a large load current change occurs. They can also respond slowly by varying the reference voltage. In order to increase battery lifetime, power supplies require a various range of load current and output voltage. PWM buck converter also should have a characteristic of both fast load response and reference tracking. This paper surveys a few recent techniques for reducing the settling time, and discusses their merits and limitations.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.537-541
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• 2003

In order to control the missiles by aerodynamics, control surfaces sometime called fins are used. Deflection angles of these fins are the right control variables of the aerodynamics, but aerodynamicists prefer to use analytic variables called aileron, elevator and rudder instead of these physical variables, because these three analytic variables dominantly influence on the roll, pitch and yaw channels of the missile maneuver, respectively, and each can be assumed a linear combination of four fin deflection angles. On that basis, roll, pitch and yaw autopilots for controlling the attitudes or lateral acceleration of the missile are designed, and as a consequence outputs of each autopilot are aileron, elevator and rudder commands, respectively. In the existing fin control scheme for the typical tail-fin controlled cruciform missiles, firstly these outputs are distributed to four fin defection commands, and after that four fins are actuated by fin controllers so that their deflections follow the commands. This paper shows that performance of such control schemes can be degraded significantly when fin actuators have certain physical constraints such as slew rate, voltage or current limit, uncertainty of actuator dynamics, and so on, and propose a new control scheme which alleviates such problems. This scheme can be widely applied to various fin actuation systems. But in this paper, for convenience, tail-fin controlled cruciform missile is taken as an example, and it is shown that a proposed control scheme gives better performance than the existing one.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.118-125
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• 2006

A new error amplifier is presented for fast transient response of DC-DC converters. The amplifier has low quiescent current to achieve high power conversion efficiency, but it can supply sufficient current during large signal operation. Two comparators detect large-signal variations, and turn on extra current supplier if necessary. The amount of extra current is well controlled, so that the system stability can be guaranteed in various operating conditions. The simulation results show that the new error amplifier achieves significant improvement in transient response than the conventional one.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.146-153
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• 2008

Integrated humidity sensor system with two stages operational amplifier has been designed and fabricated by $0.8{\mu}m$ analog mixed CMOS technology. The system (28 pin and $2mm{\times}4mm$) consisted of Wheatstone-bridge type humidity sensor, resistive type humidity sensor, temperature sensors and operational amplifier for signal amplification and process in one chip. The poly-nitride etch stop process has been tried to form the sensing area as well as trench in a standard CMOS process. This modified technique did not affect the CMOS devices in their essential characteristics and gave an allowance to fabricate the system on same chip by standard process. The operational amplifier showed the stable operation so that unity gain bandwidth was more than 5.46 MHz and slew rate was more than 10 V/uS, respectively. The drain current of n-channel humidity sensitive field effect transistor (HUSFET) increased from 0.54 mA to 0.68 mA as the relative humidity increased from 10 to 70 %RH.

• Tribology and Lubricants
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• v.38 no.5
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• pp.191-198
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• 2022

With the world's fast expanding energy usage comes a slew of new issues. Because one-third of energy is lost in overcoming friction, tremendous effort is being directed into minimizing friction. Surface texturing is the latest surface treatment technology that uses grooves and dimples on the friction surface of the machine to significantly reduce friction and improve wear resistance. Despite the fact that many studies on this issue have been conducted, most of them focused on parallel surfaces, with relatively few cases of converging films, as in most sliding bearings. This study investigated the lubrication performance of surface-textured inclined slider bearings. We analyzed the continuity and Navier-Stokes equations using a commercial computational fluid dynamics code, FLUENT. The results show the pressure and velocity distributions and the lubrication performance according to the number and orientation of rectangular dimples. Partial texturing somewhat improves the lubrication performance of inclined slider bearings. The number of dimples with the maximum load-carrying capacity (LCC) and minimum friction is determined. When the major axis of the dimple is arranged in the sliding direction, the LCC and friction reduction are maximized. However, full texturing significantly reduces the LCC of the slider bearing and increases the flow rate. The results have the potential to improve the lubrication performance of various sliding bearings, but further research is required.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.6
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• pp.39-47
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• 1998

A fourth-order $\Sigma$-$\Delta$ modulator is designed and implemented in 0.6 $\mu\textrm{m}$ CMOS technology. The modulator is verified by introducing nonlinear factors such as DC gain and slew rate in system model that determines the transfer function in S-domain and in time-domain. Dynamic range is more than 110 dB and the peak SM is 102.6 dB at a clock rate of 2.8224 MHz for voiceband signal. The structure of a ∑-$\Delta$ modulator is a modified fourth-order ∑-$\Delta$ modulator using direct feedback loop method, which improves performance and consumes less power. The transmission zero for noise is located in the first-second integrator loop, which reduces entire size of capacitors, reduces the active area of the chip, improves the performance, and reduces power dissipation. The system is stable because the output variation with respect to unit time is small compared with that of the third integrator. It is easy to implement because the size of the capacitor in the first integrator, and the size of the third integrator is small because we use the noise reduction technique. This paper represents a new design method by modeling that conceptually decides transfer function in S-domain and in Z-domain, determines the cutoff frequency of signal, maximizes signal power in each integrator, and decides optimal transmission-zero frequency for noise. The active area of the prototype chip is 5.25$\textrm{mm}^2$, and it dissipates 10 mW of power from a 5V supply.