• 한국소음진동공학회논문집
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• 제20권12호
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• pp.1190-1199
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• 2010

This paper reports active control of clamped beams using acceleration feedback controllers (AF). The equations of motion of clamped beam under force and moment pairs were derived and the equations of AF controllers were formulated. The effect of the parameters - gain and damping ratio - of the AF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the AF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies. The increase of the damping ratio of the AF controller leads to decrease the magnitude of the open loop transfer function and modifies its phase characteristics to be more stable. Three AF controllers connected in parallel were then proposed. Each AF controller is tuned at the 2nd, 3rd and 4th modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the 3 modes can be obtained.

• Journal of Power Electronics
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• 제13권3호
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• pp.447-457
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• 2013

For grid-connected LCL-filtered inverters, resonance yields instability and low bandwidth. As a result, careful designs are required. This paper presents a systematic current control structure, where pole assignment consisting of one or more feedbacks is the inner loop, and the outer loop is the direct grid current control. Several other issues are discussed, such as the inner-loop feedback choices, pole-assignment algorithms, robustness and harmonic rejection. Generally, this kind of strategy has three different types according to the inner-loop feedback choices. Among them, a novel pole-assignment algorithm has been proposed, where the inner control maintains four freely-assigned poles which are just two pairs of conjugated poles located at the fundamental and resonance frequencies separately. It has been found that with the different types, the steady-state and dynamic performances are quite different. Finally, simulations and experiments have been provided to verify the control and design of the proposed methods.

• 한국인공지능학회지
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• 제12권3호
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• pp.9-15
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• 2024

This paper addresses the critical need for quadcopters in GPS-denied indoor environments by proposing a novel attitude control mechanism that enables autonomous navigation without external guidance. Utilizing AR marker detection integrated with a dual PID controller algorithm, this system ensures accurate maneuvering and positioning of the quadcopter by compensating for the absence of GPS, a common limitation in indoor settings. This capability is paramount in environments where traditional navigation aids are ineffective, necessitating the use of quadcopters equipped with advanced sensors and control systems. The actual position and location of the quadcopter is achieved by AR marker detection technique with the image processing system. Moreover, in order to enhance the reliability of the attitude PID control, the dual closed loop control feedback PID control with dual update periods is suggested. With AR marker detection technique and autonomous attitude control, the proposed quadcopter system decreases the need of additional sensor and manual manipulation. The experimental results are demonstrated that the quadrotor's autonomous attitude control and operation with the dual closed loop control feedback PID controller with hierarchical (inner-loop and outer-loop) command update period is successfully performed under the non-GPS aided indoor environment and it enhanced the reliability of the attitude and the position PID controllers within 17 seconds. Therefore, it is concluded that the proposed attitude control mechanism is very suitable to GPS-denied indoor environments, which enables a quadcopter to autonomously navigate and hover without external guidance or control.

• 융합신호처리학회논문지
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• 제2권3호
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• pp.57-64
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• 2001

본 논문은 시스템의 불확실성과 외란의 불확실성에도 불구하고 원하는 시스템 성능을 만족할 수 있는 강인한 제어기 설계에 대하여 서술한다. QFT(Quantitative Feedback Theory)에 근거한 강인한 제어기 설계과정은 시스템 파라미터 변동과 설계사양을 고려하여 결정되는 템플레이트, 한계조건 그리고 루프형성을 거친다. 설계된 제어기의 성능을 입증하기 위해 파라미터 변동에 매우 민감하고, 비선형성이 강하며 불안정한 특성을 지닌 도립진자시스템에 대하여 적용한다. 설계된 제어기에 대한 시뮬레이션과 실험결과들은 파라메파 변동과 외란에 강인한 제어성능을 보인다.

• 제어로봇시스템학회논문지
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• 제9권2호
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• pp.117-123
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• 2003

Rotational machines such as optical disk drives, hard disk drives, and so on are subject to periodic disturbances caused by their mechanical characteristics. In the meanwhile, it is well known that repetitive control rejects periodic disturbance effectively. This paper presents a practical application of repetitive control to the track-following servo of an optical disk drive. The repetitive control system is composed of two repetitive controllers which compensate for periodic disturbances generated by track geometry and eccentric rotation of disk and a feedback controller stabilizing the feedback loop. A robust stability for all plant uncertainties is proved using linear matrix inequalities (LMIs). In the controller design, a weighting function is introduced for the feedback controller to ensure a minimum loop gain and a sufficient phase margin. The repetitive controllers and the feedback controller are designed by solving an optimization problem which can consider the robust stability condition and the system performance. The developed repetitive control system is implemented in the digital control system with a 16-bit fixed-point digital signal processor (DSP). Through simulation and experiment. The feasibility of the proposed repetitive control system is verified.

• 전기전자학회논문지
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• 제21권2호
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• pp.154-157
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• 2017

본 논문에서는 하나의 입력 전압을 받아 두 개의 출력전압을 가지는 LDO 레귤레이터를 제안한다. 두 개의 출력은 각각의 피드백단을 갖는다. 또한 각각의 피드백 단은 서로 피드백 루프를 공유하며, 서로 피드백 루프를 공유 할 시 서로 미치는 영향을 최소화 하기 위하여 피드백 역할을 하는 PMOS를 추가하여 Load Transient Response를 완화 시켰다. 또한 하나의 바이어스 회로와 하나의 패스 트랜지스터를 사용함으로써 기존 두 개의 출력전압을 얻기 위해 두 개의 LDO 레귤레이터를 사용할 때 대비 면적이 절반으로 줄어들었다.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.56-64
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• 2019

Recently, as the environmental regulation for earth moving equipment has been tightened, advanced systems using electronic control have been introduced for energy savings. An IMV(Independent Metering Valve), which consists of four 2-way valves, is one of the electro-hydraulic control systems that provides more flexible controllability and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully realize an IMV, a two-stage bi-directional flow control valve which can regulate the large amount of flow in both directions, should be developed in advance. A simple design that allows proportional flow control to apply the pilot pressure from the current-controlled solenoid to the spring loaded flow control spool and thus valve displacement, is proportional to the solenoid current. However, this open-loop type valve is vulnerable to flow force which directly affects the valve displacement. Force feedback servo of which the position loop is closed by the feedback spring which interconnects the solenoid valve and flow control spool, could compensate for the flow force. In this study, linearity for the solenoid current input and robustness against load pressure disturbance is investigated by linear analysis of the static nonlinear equations for the IMV proportional flow control valve with feedback spring. Gains of the linear system confirm the performance improvement with the feedback spring design.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.525-536
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• 2017

Course keeping is hard to implement under the condition of the propeller stopping or reversing at slow speed for berthing due to the ship's dynamic motion becoming highly nonlinear. To solve this problem, a practical Maneuvering Modeling Group (MMG) ship mathematic model with propeller reversing transverse forces and low speed correction is first discussed to be applied for the right-handed single-screw ship. Secondly, a novel PID-based nonlinear feedback algorithm driven by bipolar sigmoid function is proposed. The PID parameters are determined by a closed-loop gain shaping algorithm directly, while the closed-loop gain shaping theory was employed for effects analysis of this algorithm. Finally, simulation experiments were carried out on an LPG ship. It is shown that the energy consumption and the smoothness performance of the nonlinear feedback control are reduced by 4.2% and 14.6% with satisfactory control effects; the proposed algorithm has the advantages of robustness, energy saving and safety in berthing practice.

• Journal of Power Electronics
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• 제12권6호
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• pp.886-894
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• 2012

This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.

• 한국시스템다이내믹스연구
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• 제10권4호
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• pp.53-72
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• 2009

More than 24.43 million people received a special pardon to mark the anniversary of Liberation Day on Aug. 15 and to commemorate other national event, during 15years(1995-2009), in this period six times of presidential pardon was implemented. The special pardon allows traffic law violator to drive again with their violation records wiped clean. But traffic records show that traffic accidents used to increase very fast in a short period by up to 3-15 percent after implementing the every massive pardons. This study explores the causal feedback relationship between presidential special pardon for traffic law violators and the occurrence of an traffic accidents using a system thinking approach and simulation modelling. Particularly, this study focused on the analysing significant negative impact of the traffic pardon on the occurrence of worrisome traffic accidents. The results of this study show that presidential special pardon have had impact on the traffic accidents as a increasing leverage of positive feedback loop and the obedience of traffic law as a decreasing leverage of negative feedback loop. Finally, this study conclude that the cyclical increasing pattern of traffic accident is resulting from the periodically conducted presidential pardons with political aims.