• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.114-122
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• 1995

A digital preview controller is designed for tandem cold mills to achieve a more improvement of the thickness accuracy. Simultaneously a blocked noninteracting controller is synthesized for rejecting the interactive effects among adjacent stands and for controlling independently each roll stand of tandem cold mills. The performance effects and characteristics of the suggested roll contol system are discussed in the practical viewpoint. The simulaltion results show that the thickness accuracy of tandem cold mills can be largely improved by the blocked noninteracting and digital preview controller.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.138-147
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• 1995

The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.85-90
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• 2001

Recent general Press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending ang1e and marking-off works to calculate bending length. Also, the hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time and high accuracy bending work.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.26-36
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• 2010

This paper provides a description of the combustion model to obtain an accurate dynamic engine phenomena that satisfies real-time simulation for model-based engine control. The combustion chamber is modeled as a storage device for mass and energy. The combustion process is modeled in terms of a two-zone model for the burned and unburned gas fractions. The mass fraction burnt is modeled in terms of a Wiebe function. The instantaneous net engine torque is calculated from the engine speed and the instantaneous piston work. The modeling accuracy has been tested with a cylinder pressure data on a test bench and also the ability of real-time simulation has been checked. The results show that combustion model yields sufficiently good performance for the model-based control logic design. However the influence factors effected on model accuracy are some room for improvement.

• Journal of the Korean Mathematical Society
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• v.49 no.3
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• pp.549-569
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• 2012

In this paper asymptotic error expansions for mixed finite element approximations to a class of second order elliptic optimal control problems are derived under rectangular meshes, and the Richardson extrapolation of two different schemes and interpolation defect correction can be applied to increase the accuracy of the approximations. As a by-product, we illustrate that all the approximations of higher accuracy can be used to form a class of a posteriori error estimators of the mixed finite element method for optimal control problems.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.987-988
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• 2008

In this paper, we propose a rotation invariant face detection method using Haar-like feature variation. Previous approaches using rectangular features can be calculated very fast. But rectangular features is weak in rotated face. Rotated Haar-like features can get high accuracy, but the performance is slow because it can't use the integral image. Our method vary Haar-like features keeping rectangular. this method makes the performance a bit slow, but gives better accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1139-1143
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• 1991

Using industrial robots and sensors, we developed an inline car body inspection system which proposes high flexibility and sufficient accuracy. Car Body Inspection(CBI) cell consists of two industrial robots, two corresponding carriages, camera vision system, a process computer with multi-tasking ability and several LDS's. As industrial robots guarantee sufficient repeatabilities, the CBI cell adopts the concept of relative measurement instead of that of absolute measurement. By comparing the actual measured data with reference data, the dimensional errors of the corresponding points can be calculated. The length of the robot arms changes according to ambient temperature and it affects the measuring accuracy. To compensate this error, a robot arm calibration process was realized. By measuring a reference jig, the differential changes of the robot arms due to temperature fluctuation can be calculated and compensated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.20-24
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• 1997

In general, pantograph type manipulators are used for carrying heavy payloads with positional accuracy. In this paper, a double pantograph type manipulator, activated by two slider joints, is studied for applying to file handing machine in atomic power plant. In order to realize the stable horizontal movement of a heavy fuel rod whit good positional accuracy, methods for allocating slider and finding constant joint rates are proposed. In addition, the static deflection of the proposed mechanism was studied using transfer-stiffness matrix method. A neural network control algorithm which compensates static deflections is explored with computer simulations.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.902-906
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• 2008

The linear motors are easily affected by load disturbance, force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbance. For highspeed/high-accuracy position control of a linear-motor-driven two axes, a nonlinear adaptive controller including a cross-coupling algorithm is designed in this paper. The nonlinear effects such as friction and force ripple are estimated and compensated. An enhanced approach for cross-coupling algorithm is proposed to effectively improve the biaxial contour accuracy with the closed-loop stability. The proposed controller is evaluated through the computer simulations.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.729-737
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• 2009

This paper introduces the machine tools feed system, which can be optimized the control's performance through simulation and the adjustment of the mechanical components. One method simulates the frequency response of the speed-loop with the design value using the MATLAB application, so that all of the interpolation axis can be equal to the response bandwidth, resulting in a high accuracy rate. The other method sees the mechanical component being adjusted by analyzing the results of various experiments. Lastly, this client's program is able to change the parameters that are related to the FFD, as well as the parameters in the friction compensation of the OPEN-CNC.