• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.56-64
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• 2013

We propose an efficient minimum-time cornering motion planning algorithms for differential-driven wheeled mobile robots with motor control input constraint, under piecewise constant control input sections. First, we established mobile robot's kinematics and dynamics including motors, divided the cornering trajectory for collision-free into one translational section, followed by one rotational section with angular acceleration, and finally the other rotational section with angular deceleration. We constructed an efficient motion planning algorithm satisfying the bang-bang principle. Various simulations and experiments reveal the performance of the proposed algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1322-1325
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• 1997

A new feedback control law design techniqed usign of-off thrusters for the rotational maneuver of a flexible arm is discussed in this study. a two state on-off thruster actuator is taken as a primary actuation device for theis study. The on-off thruster operation is emulated in conjunction with the conventioal minimum-time trackig control law. The actuator input region is divided into two separate parts ; one is constant input and the other is time varying tegion. the new control law has potential applicatioin for the relatively low frequency structure such as large flexible space structure being currently used in various space echnology areas.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.86-88
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• 2008

The rotational loss is one of the most important problems for the practical use of the high power Flywheel Energy Storage System (FESS). This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized any and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the high power FESS.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.883-886
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• 1998

In order to detect the user's gaze position on a monitor by computer vision, the accurate estimations of 3D positions and 3D motion of facial features are required. In this paper, we apply a EKF(Extended Kalman Filter) to estimate 3D motion estimates and assumes that its motion is "smooth" in the sense of being represented as constant velocity translational and rotational model. Rotational motion is defined about the orgin of an face-centered coordinate system, while translational motion is defined about that of a camera centered coordinate system. For the experiments, we use the 3D facial motion data generated by computer simulation. Experiment results show that the simulation data andthe estimation results of EKF are similar.e similar.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.898-902
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• 2006

The motion of a system composed of a plate, constant springs and varying dampers is considered when the system is subject to harmonic force. Letting the frequencies of harmonic force and damper variation ${\Large f}_1\;and\;{\Large f}_2$ respectively, the displacement at the center of the plate has the strongest component at frequency ${\Large f}_1$. The angular displacement of the plate has strong components at ${\Large f}_1-{\Large f}_2$ and the natural frequency of the rotational mode of the system. If these two frequencies coincide, the plate oscillates with almost single frequency and a large amplitude. Part of these simulation results are proved analytically.

• 전기학회논문지
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• 제62권9호
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• pp.1223-1227
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• 2013

If the factory test efficiency and field operation efficiency of water turbine are different from each other, issues for efficiency warranty can be raised. So, This paper shows the result for comparative analysis of field operating efficiency vs plant testing efficiency of the water turbine generator installed in agricultural reservoir. The efficiency of the induction generator is analyzed by the change of rotational speed with the parameter obtained by test, the efficiency of water turbine is calculated by the change of head with the design flow. Efficiency deviation of induction generator is lower but the variation of developed power is pretty high near the rated speed and the efficiency variation of water turbine is high by the fluctuation of head for constant flow. It was found that factory test efficiency and total efficiency of water turbine generator calculated according to the rotational speed are very close.

• 한국소음진동공학회논문집
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• 제16권9호
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• pp.958-963
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• 2006

The motion of a system composed of a plate, constant springs and varying dampers is considered when the system is subject to harmonic force. Letting the frequencies of harmonic force and damper variation $f_1\;and\;f_2$, respectively, the displacement at the center of the plate has the strongest component at frequency $f_1$. The angular displacement of the plate has strong components at $f_1-f_2$ and the natural frequency of the rotational mode of the system. If these two frequencies coincide, the plate oscillates with almost single frequency and a large amplitude. These results can be applied to development of a moment shaker with low frequencies.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.103-106
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• 2004

The new rheology fabrication process has been developed to rheo die casting and rheo forming process. Thixoforming process has disadvantages in terms of induction reheating process, scrap recycling, loss of raw material and cycle time. Therefore, to reduce the number of process, new rheology fabrication process with specially designed the rotational barrel type equipment has been proposed to apply in various part productions. The barrel type equipment, which could continuously fabricate the rheology materil, was specially designed to have a function to control cooling rate, shear rate and temperature. During the continuous rotation of barrel with a constant temperature, the shear rate is controlled with the rotation speed. The barrel surface has both the induction heating system and the cooling system to control the temperature of molten metal. By using this system, the effect of the rotation speed and the rotation time on the microstructure was widely examined. The possibility for the rheoforming process was investigated with microstructural characteristic.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.358-361
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• 2005

The rotational barrel type equipment has been designed for the new rheology fabrication process. During the continuous rotation of barrel with a constant temperature, the shear rate is controlled with the rotation speed and rotation time of barrel. The barrel surface can be controlled the temperature by the induction heating and cooling system. Many experiments were widely examined by using this system with controlling the rotation speed and the rotation time. The possibility for the rheoforming process was investigated with microstructural characteristics.

• 오토저널
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• 제12권4호
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• pp.66-74
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• 1990

Friction between piston-ring assembly and cylinder wall of a spark ignition engine was evaluated under various engine operating conditions utilizing a grasshopper linkage system. The friction force was estimated by the force balance relation at the small end of connecting rod. Three forces were chosen to be measured for the objective. They were gas pressure inside the cylinder, inertia force of the piston-ring assembly, and the force exerted by the connecting rod. These forces were measured by a piezo type pressure sensor, an accelerometer and strain gauges, respectively. Comparisons were made with the frictional force evaluated by the conventional method where the assumption of constant rotational speed of engines was adopted. Due to the variation of rotational speed of engines, the conventional method was found to lead to a large error in the evaluation of the frictional force.