• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1137-1146
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• 2016

• Journal of Biosystems Engineering
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• 제14권4호
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• pp.229-241
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• 1989

The purposes of this study were to develop an electronic-hydraulic draft control system for tractor implements, to investigate the control performance of the system and the possibility of adaptation to the conventional tractor. Experiments were carried out to investigate the responses of the system to the step and sinusoidal inputs in draft control. The effects of control mode, hydraulic flow rate, reference deadband, and proportional constant on control performance of the system were investigated. Moreover, the effects of filtering signals from draft sensor were also investigated. The following conclusions were derived from the study; 1. In draft control, there were hunting problems in controlling the implement without filtering the draft signals. Filtering was performed by a control program of electronic controller and the control performance and stability of the system were improved significantly. 2. For the draft control system operated on on-off control mode, draft was controlled within ${\pm}27-{\pm}55kg_f$ to the reference draft when the hydraulic flow rates were 5-15 l/min. For the draft control system operated on PWM control, draft was controlled within ${\pm}27kg_f$ to the reference draft regardless of hydraulic flow rates. 3. In the frequency responses of the draft control system, control performance on PWM control mode was not better than on on-off control mode because of characteristics of hydraulic valve and drafe sensor. As the hydraulic flow rates increased for the system operated on on-off control mode, the corner frequency of amplitude attenuation increased, but the corner frequency of phase-angle change remained nearly the same. But, the system was unstable beyond the frequency of 3.1 rad/s. 4. The electronic-hydraulic hitch control system developed in this study showed superior control performance, stability and convenience compared to conventional mechanical-hydraulic hitch control system. It is considered to be a superior replacement for the conventional mechanical-hydraulic hitch control system.

• Journal of the Optical Society of Korea
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• 제2권1호
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• pp.34-37
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• 1998

We present a novel method for the stabilization of the Sagnac current sensor with active twist control. The sensor output was improved more than 8 times by employing the proposed stabilization method. Stability within $\pm$1.7% was demonstrated between 36$^{\circ}C$ and 62$^{\circ}C$.

• 전자공학회논문지C
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• 제36C권7호
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• pp.56-64
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• 1999

본 논문에서는 연속 어핀 Takagi-Sugeno 퍼지 시스템의 안정도를 판정하는 새로운 방법을 제안한다. 제안된 방법은 최근 각광을 받고 있는 선형 행렬 부등식이라는 컨벡스 최적화 기법을 이용하여 쉽게 구현할 수 있다. 우선 어핀 Takagi-Sugeno 퍼지 시스템이 안정하도록 되는 조건을 유도하고 이를 선형 행렬 부등식의 형태로 변형하고 수치적 접근방식을 제안한다. 끝으로 컴퓨터 모의 실험을 통하여 제안한 방법의 타당성을 확인한다.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.123-141
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• 2018

Hardware-in-the-loop (HiL) simulation is a very powerful tool to design, test and verify automotive control systems. However, well-validated and high degree of freedom vehicle models have to be utilized in these simulations in order to obtain realistic results. In this paper, a vehicle dynamics model developed in the Carsim Real Time program environment and its validation has been performed using experimental results. The developed Carsim real time model has been employed in the Tofas R&D hardware-in-the-loop simulator. Experimental and hardware-in-the-loop simulation results have been compared for the standard FMVSS No. 126 test and the results have been found to be in good agreement with each other. Two electronic stability control (ESC) algorithms, named the Basic ESC and the Integrated ESC, taken from the earlier work of the authors have been tested and evaluated in the hardware-in-the-loop simulator. Different evaluation methods have been formulated and used to compare these ESC algorithms. As a result, the Integrated ESC system has been shown superior performance as compared to the Basic ESC algorithm.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.150-155
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• 1998

Sliding mode control is a powerful control methodology for the control of uncertain systems. However, it and its variations have some disadvantages such as chattering and imprecise tracing performance. A novel scheme of the sliding mode control is presented for the accurate tracking control of the uncertain systems. The fuzzy logic-baced control law maintaining stability and consistent performance in the face of modeling imprecise is derived and simulation results showing its effectiveness are presented.

• 반도체디스플레이기술학회지
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• 제9권4호
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• pp.7-12
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• 2010

Field-emission characteristics of carbon nanotubes(CNTs), which were grown on conical-type tungsten micro-tips by using an electrophoretic deposition(EPD) method, were examined. The EPD method proved to be convenient to manipulate and arrange CNTs from well dispersed suspensions onto such tip-type substrates. The growth rate of CNTs was proportional to the applied d.c. bias voltage and the process time. It was observed from the Raman study that the EPDproduced CNTs showed better crystal qualities with the Raman intensity ratio( $I_D$/$I_G$) of 0.41-0.42 than the CVD-produced CNTs and their crystal qualities could be further improved by thermal annealing. The electron emitters based on the EPDCNTs showed excellent field emission properties, such as the threshold voltage for electron emission of about 620 V and the maximum emission current of about 345 ${\mu}A$. In addition, the EPD-CNTs exhibited the stable long-term(up to 40 h) emission capability and the emission stability was enhanced by thermal annealing.

• Transactions on Control, Automation and Systems Engineering
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• 제1권1호
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• pp.44-49
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• 1999

This paper presents a new T-S(Tae-Sugeno) fuzzy controller design method satisfying the output energy bound. Maximum output energy via a quadratic Lyapunov function to obtain the bound on output energy is derived. LMI(Linear Matrix Inequality) problems which satisfy an output energy bound for both of the continuous-time and discrete-time T-S fuzzy control system are also derived. Solving these LMIs simultaneously, we find a common symmetric positive definite matrix P which guarantees the global asymptotic stability of the system and stable feedback gains K's satisfying the output energy bound. A simple example demonstrates validity of the proposed design method.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권3호
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• pp.171-180
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• 2014

In this paper, a multiple sliding surface (MSS) controller for a twin rotor multi-input-multioutput system (TRMS) with mismatched model uncertainties is proposed. The nonlinear terms in the model are regarded as model uncertainties, which do not satisfy the standard matching condition, and an MSS control technique is adopted to overcome them. In order to control the position of the TRMS, the system dynamics are pseudo-decomposed into horizontal and vertical subsystems, and two MSSs are separately designed for each subsystem. The stability of the TRMS with the proposed controller is guaranteed by the Lyapunov stability theory. Some simulation results are given to verify the proposed scheme, and the real time performances of the TRMS with the MSS controller show the effectiveness of the proposed controller.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1220-1223
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• 2002

In this paper, numerical robust stability analysis method and its design are presented. L$_2$robust stability of the fuzzy system is analyzed by casting the systems into the diagonal norm bounded linear differential inclusions (DNLDI) formulation. Based on the linear matix inequality (LMI) optimization programming, a numerical method for finding the maximum stable ranges of the fuzzy feedback linarization control gains is proposed.