• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.211-212
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• 2003

Three dimensional flow above a sand dune has been studied numerically by using Large-Eddy Simulation (LES) method. The movement of the sand which is formed by converging wind directions has been investigated. The numerical method employed in this study can be divided into three parts: (i) calculation of the air flow above the sand dune using MAC method with a generalized coordinate system; (ii) estimation of the sand transfer caused by the flow through the friction; (iii) determination of the shape of the sand surface. Since the computational area has been changed due to step (iii), (i)­(iii) are repeated. The simulated dune, which has initially elliptic cross section, extending at the converging direction which is known as linear dunes.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.36-42
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• 2001

In this paper, PSD(Position Sensitive Detector) sensor system that estimates position for moving objects in 2D plane is developed. PSD sensor is used to measure the position the position of and incidence light in real-time. To get the position of light source of moving target, a new parameter calibration algorithm and neural network technique are proposed and applied. Real-time position measurements of the mobile robot with light source is examined to validate the proposed method. It is shown that the proposed technique provides accurate position estimation of the moving object.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.519-523
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• 2016

This paper proposes a method of estimating the actuator faults of a hexacopter without using encoders when one or more of six actuators do not operate normally. In the case of the hexacopter, a Pseudo-Inverse matrix is generally used to obtain the rotational speed of the actuators because the matrix that transforms the rotational speed of the actuators into the thrust and torque of the body coordinate system is not a square matrix. However, the method based on the Pseudo-Inverse matrix cannot detect the actuator faults correctly because the Pseudo-Inverse matrix is approximate. In the proposed method, the actuator faults are estimated by modifying the transform matrix using the property that the actuators of the hexacopter are symmetrical. The simulation results show the effectiveness of the proposed method when faults occur in one or more of the six actuators.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1045-1048
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• 1999

In this paper, we calculate the moving velocity of viewer by using two eye images obtained at different time through the camera. This process is necessary for future 3D display technique, in which moving viewer can see 3D image continuously We firstly extract two eyes image and calculate the pixel coordinate of center point between two eyes. Next, we calculate the moving velocity in two dimension by comparing two center point coordinates obtained at different time.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.984-989
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• 2008

An estimation of high-order damping in flexible multibody dynamic simulation is introduced in this paper. The suggested damping model based on the experimental modal analysis leads to more accurate correlation results comparing to the traditional linear damping model because it directly uses the modal parameters of each mode achieved from experiment even high frequency modes. The modal parameters until the 5th mode are extracted from the experimental modal testing of the flexible beam using a high speed camera. And using the measured damping ratio and natural frequency until the 5th mode, the generic damping model is constructed. Then, the ANCF (absolute Nodal Coordinate Formulation) simulation results are compared to experimental results until the 5th mode.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.366-370
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• 1998

Indirect vector control for induction motors requires the use of observers for estimation or observation of rotor flux magnitude and position. In this paper, authors discribe the induction motor vector control and introduce a nonlinear observer, named ELO(extended Luenberger Observer), without simulation results as a preliminary work for trial application. Normally, design of nonlinear observer need coordinate transfromation and linearization through solving the partial different equation. However, ELO requires minimal solution of nonlinear partial differential equation. Simulation was performed by under the enviroment of Matlab and Simulink without the proposed observer because we are still working. Simulation was performed with conventional flux observer, a dc-ac inverter by SVPWM technique, a vector controller armed with multiple PI controllers

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.304-309
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• 1998

In this paper, authors introduce an application of a nonlinear rotor flux observer, known under the name of ELO(extended Luenberger Observer), for direct rotor field oriented control(DRFOC) of induction motor. ELO requires no solution of nonlinear partial differential equation for its coordinate transformation and linearization used for the nonlinear observer design. Its simulation results concerned to different level of unknown variables of load torque and rotor resistance show high accuracy on rotor flux estimation in steady state.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.188-188
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• 2000

The most important problem in target tracking can be said to be modeling the tracking system correctly. Although the simple linear dynamic equation for this model has used until now, the satisfactory performance could not be obtained owing to uncertainties of the real systems in the case of designing the filters baged on the dynamic equations. In this paper, we propose the extended robust Kalman filter (ERKF) which can be applied to the real target tracking system with the parameter uncertainties. A nonlinear dynamic equation with parameter uncertainties is used to express the uncertain system model mathematically, and a measurement equation is represented by a nonlinear equation to show data from the radar in a Cartesian coordinate frame. To solve the robust nonlinear filtering problem, we derive the extended robust Kalman filter equation using the Krein space approach and sum quadratic constraint. We show the proposed filter has better performance than the existing extended Kalman filter (EKF) via 3-dimensional target tracking example.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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• pp.267-271
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• 2002

The Hotelling transform is based on statistical properties of an image. The principal uses of this transform are in data compression. The basic concept of the Hotelling transform is that the choice of basis vectors pointing the direction of maximum variance of the data. This property can be used for rotation normalization. Many objects of interest in pattern recognition applications can be easily standardized by performing a rotation normalization that aligns the coordinate axes with the axes of maximum variance of the pixels in the object. However, this transform can not be used to rotation normalization of color images directly. In this paper, we propose a new method for rotation normalization of color images based on the Hotelling transform. The Hotelling transform is performed to calculate basis vectors of each channel. Then the summation of vectors of all channels are processed. Rotation normalization is performed using the result of summation of vectors. Experimental results showed the proposed method can be used for rotation normalization of color images effectively.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2927-2929
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• 2009

The hydricities of d$^6$ metal hydride complexes in aqueous solution were calculated by using density functional theoretical (DFT) calculations coupled with a Poisson-Boltzmann (PB) solvent model. Hydricity describes the hydride donor ability of the metal-hydrogen bond, which assists in the study of the mechanism of many catalytic processes and chemical reactions that involve transition metal hydrides. The calculation scheme produced hydricity values that were in good agreement with experimental estimation. The inclusion of a water molecule as a weakly bound ligand to five-coordinate metal complexes gave an improved correlation result.