• 동력기계공학회지
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• 제21권2호
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• pp.27-34
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• 2017

A heave motion of the offshore crane system with load is affected by unpredictable external factors. Therefore the offshore crane must satisfy rigorous requirements in terms of safety and efficiency. This paper intends to reduce the heave displacement of load position which is produced by rope extension and sea wave disturbance in vertical motion. In this system, the load position is compensated by the winch actuator control. The rope is modeled as a mass-damper-spring system, and a controller is designed by the input-output linearization method. The model system and the proposed control method are evaluated on the simulation results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.387-390
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• 2007

Recently the diameter of the 5MW wind turbine reaches 126m, and the tower height is nearly the same with the wind turbine diameter. The blade will experience periodic inflow oscillation due to blade rotation inside the ground shear flow region, that is, the inflow velocity is maximum at uppermost position and minimum at lowermost position. In this study we compare the aerodynamic data between two inflow conditions, i.e, uniform flow and normal wind profile. From the computed results all of the relative errors for oscillating amplitudes increased due to the ground shear flow effect. Especially My at hub and $F_x$, $M_y$, $M_z$ at LSS increased enormously. It turns out that the aerodynamic analysis including the ground shear flow effect must be considered for fatigue load analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.369-378
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• 1999

This paper presents position control of an electro-hydraulic servo system whoch is operated by four 2-2way high speed on-off valves with either PWM PID control method or sliding mode control method, The advantages of using high speed on-off valves instead of electo-hydraulic servo valves or electro-hydraulic proportional valves are low price robustness for oil contamination and direct control without a D/A converter. The system consists of load cylinder inertia car potentiometer and external load cylinder. The experiments were carried out under several conditions and the results were compared. As a result the sliding mode method has shown good control performance and the robust and stable positioning of the elector-hydraulic servo system can be achieved accurately.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.436-442
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• 2012

This paper develops a design methodology of a decentralized fuzzy load-frequency controller for a large-scale nonlinear power system with valve position limits on governors. The concerned system is locally exactly modeled in Takagi-Sugeno's form. Sufficient design condition for uniform ultimate boundedness of the closed-loop system is derived based on the overlapping decomposition. Convergence of all incremental frequency deviations to zero is also investigated. A simulation result is provided to visualize the effectiveness of the proposed technique.

• 한국분무공학회지
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• 제19권2호
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• pp.64-68
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• 2014

A driving vehicle performance which is driven by FTP-75 mode was simulated by computer. Throttle valve position, engine speed, air mass flow rate, fuel consumption et al. were computer simulated. A set of engine part load performance data, automatic transmission shift map and vehicle specifications were used for the computer simulation. Throttle valve position, engine speed, air mass flow rate et al. measured for evaluating the computer simulation results by driving the vehicle with FTP-75 mode on a chassis dynamometer. GT-Power$^{(R)}$ software was used for the computer simulation of the driving vehicle performance. Experimental fuel consumption rate was measured by using an ECU HILS fuel injection system. The experimental data and simulation results were compared. The computer simulation of the driving vehicle performance predicts the measured data well comparatively.

• 설비공학논문집
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• 제24권4호
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• pp.330-335
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• 2012

A characteristic behavior of the thermal storage tank for varying thermal load in heat pump water heater was studied. The control method was suggested and applied. By measuring the temperature within the storage tank, the heat pump was ON/OFF controlled. The appropriate measuring position and the size of heat exchanger gives the minimized power consumption of heat pump. As the length of heat exchanger increases, the temperature measuring position goes down of the storage tank and the power consumption increases.

• Journal of Power Electronics
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• 제19권6호
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• pp.1449-1457
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• 2019

This paper presents two voltage domain stacking topologies for powering integrated digital loads such as multiprocessors or 3D integrated circuits. Pairs of loads and capacitors are connected in series to form a stack of voltage domains. The voltage is balanced by switching the position of the capacitors in one case and the position of the loads in the other case. This method makes the voltage regulation robust to large differential load power consumption. The first configuration can be named the load stacking topology. The second configuration can be named the capacitor stacking topology. This paper aims at proposing and comparing these two topologies. Models of both topologies and a switching scheme are presented. The behavior, control scheme, losses and overall performance are analyzed and compared theoretically in simulation and experiments. Experimental results show that the capacitor stacking topology has better performance with a 30% voltage ripple reduction.

• 전력전자학회논문지
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• 제26권5호
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• pp.349-356
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• 2021

Permanent magnet synchronous motors are mainly used in the traction of electric vehicle and home application products including air-conditioners and refrigerators. For sensorless control without rotor position sensors, I-F control is applied for initial starting at low speeds, and mode is changed to sensorless control when the rotor speed is sufficiently accelerated for estimating rotor position. When the mode is changed to the sensorless control from the open-loop starting, the initial integral value of the speed controller should be considered by load condition; otherwise, the transition to sensorless control may fail. The sensorless transfer algorithm of PM synchronous motor based on load condition for smooth transition is proposed. The performance of the proposed sensorless transfer algorithm was verified by experiments.

• Wind and Structures
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• 제35권5호
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• pp.353-368
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• 2022

Wind turbine blades are adjusted in real-time according to the wind conditions and blade deformations to improve power generation efficiency. It is necessary to predict and reduce the aeroelastic deformations of wind turbine blades. In this paper, the equivalent model of the blade is established by the finite element method (FEM), and the aerodynamic load of the blade is evaluated based on the blade element momentum (BEM) theory. The aeroelastic coupling model is established, in which the bending-torsion coupling effect of the blade is taken into account. The steady and dynamic aeroelastic deformations are calculated. The influences of the blade section's shear centre position and the blade's sweepback design on the deformations are analyzed. The novel approaches of reducing the twist angle of the blade by changing the shear centre position and sweepback of the blade are presented and proven to be feasible.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.628-631
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• 1992

The position control for DC motor under the unpredictable load variations is presented. Neural network controller trained to deal with this problem provide the estimates of system parameters. Pole placement is also performed in accordance with them. The proposed method is validated through computer simulation.