• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.17-26
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• 1996

A submerged vehicle which is a nonlinear multivariable system must be designed to be roubst against inner-outer perturbations and hydrodynamic disturbances induces maneuvering operation. But a practical design of motion controller is limited by both mathematical modeling error and linearization errors. Performance of a motion controller based on traditional design method is very poor when the vehicle motion is under wave force distrubacnes near sea surface. Therefore, this ppaer proposes a design method of $^{\infty}$ controller under model uncertainty and sea wave disturbances. performance of the controllers by both computer simulation and HILS (hardwave in the loop simulation) shows that $H^{\infty}$ controller is more robust than PID controller under model uncertainty and high sea state...

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.61-67
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• 1999

A laser Doppler vibrometer based on the laser heterodyne interferometry is employed to measure the vibration velocity of vibrating objects. In this paper, we propose a real time analog signal processor of a laser Doppler vibrometer to reduce the degradation of Doppler signals mainly caused by environmental noises. In the proposed real time signal processor of an laser Doppler vibrometer, a pre-processor and a logical motion direction detector are designed to reduce the detection errors of the object motion direction. Also, a noise detection and rejection circuit is designed to reject the unfiltered noises.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.92-97
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• 2002

There are a lot of roots of errors in an motion of the optical pick-up actuator being one of the most significant components in a CD-ROM drive. Most of the studies recently performed have a tendency to seek for the causes from an actuator itself. This paper present the dynamic characteristics of an actuator affected by the motion of a feeding deck. The feeding system is modeled as a rigid body with eight degree-of-freedom. Using Largrange's equation, we derive the linear equations of motion with respect to the rectangular coordinate. We found the fact that the ranges of the natural frequencies of a feeding deck and an actuator are close to each other. And the time responses are also computed by the Newmark method and Runge-Kutta method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.201-211
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• 1998

The fundamental object of work measurement is to precisely establish the time standards, which are the indices of labor productivity. This study discussed the development of robot work measurement method that could establish the time standard effectively. In manufacturing industries the various robot tasks are generally classified and standardized by the unit motions. The Robot Modularization of the Unit Motion (ROMUM) was realized by the module of two steps GET and PUT unit motions. This method reduced time and effort of analysis, and could be done with ease. Therefore, ROMUM will increase the convenience of use for the unskilled worker and decrease the time required, cost and errors. And, it will contribute to reduce the unnecessary motion by robot motion analysis.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.281-286
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• 1993

In this paper, a parallel link typed wrist is developed for robotic precision assembly. The developed wrist can make the corrective motion required for compensating lateral and tilting errors. The mechanism of this wrist is one example of a motion simulator generating 6 DOF motion in space by 6 actuators connected in paralle. To make the wrist more compact, miniature DC motors containing reduction gears and servo system were used. The parallel link architecture enables a high positioning accuracy and high nominal load capacity. In this study, inverse kinematic problem is solved by using a Denavet-Hartenberg method and a simulational result about workspace of the proposed parallel mechanism is obtained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.316.2-316
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• 2002

There are a lot of roots of errors in the motion of the optical pickup actuator being one of the most significant components in the CD-ROM drive. Most of the studies recently performed have a tendency to seek fur the causes from an actuator itself. We found the fact that the range of the natural frequencies of a feeding deck and an actuator is close each other through an experiment. This paper present the dynamic characteristics of an actuator affected by the motion of a feeding deck. (omitted)

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1097-1100
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• 1999

Due to the significant computation of full search in motion estimation, extensive research in fast motion estimation algorithms has been carried out. However, most of the algorithms have the degradation in predicted images compared with the full search algorithm. To reduce an amount of significant computation while keeping the same prediction quality of the full search, we propose a fast block-matching algorithm based on gradient magnitude of reference block without any degradation of predicted image. By using Taylor series expansion, we show that the block matching errors between reference block and candidate block are proportional to the gradient magnitude of matching block. With the derived result, we propose fast full search algorithm with adaptively determined scan direction in the block matching. Experimentally, our proposed algorithm is very efficient in terms of computational speedup and has the smallest computation among all the conventional full search algorithms. Therefore, our algorithm is useful in VLSI implementation of video encoder requiring real-time application.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.367-372
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• 2000

Accuracy of a machined component is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the accuracy of this relative motion is the geometric error of machine tools. In this study, geometric error is modeled using form shaping motion of machine tool, where a form shaping function is derived from the homogeneous transformation matrix. Geometric errors are measured by laser interferometer. After that, the local positioning error can be estimated from the form shaping model and geometric error data base. From this information, we can remodel the part by shifting the design surface to the amount of positional error. By generating tool path to the redesigned surface, we can reduce the machining error.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.227-230
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• 1999

In this paper, the machining characteristics of high speed ball end milling affected by the rotational error of high speed spindle using air bearing are investigated. The error motions of a spindle have generally influenced on the surface roughness, the form accuracy, the tool life, etc. in end milling. Experiments are carried out over a wide range of rotational speeds(10,000-50,000rpm). The rotational errors of the spindle are measured by the gap sensor mounted on the spindle shaft at various cutting speeds. The relations between the surface roughness and the spindle error motion are presented. Results show that the rotational accuracy of the spindle directly affects the surface roughness of the machined surface.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.103-111
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• 2009

Multi-climbing hydraulic robots are used to lift construction factory (CF) synchronously for applications in the automation of a high-rise building construction. In this study, synchronous motion controller is proposed for the hydraulic robots, whose strategy is not only to make each robot follow the reference path basically by sliding-mode control, but also to synchronize motions of two adjacent cent robots consecutively by cross-coupled control technique. Simulations are performed by using SIMULINK for a system similar to a practical application that includes unbalance in CF and wind disturbance. The results show that the proposed controller significantly reduces synchronous errors, compared to the individual controller for each hydraulic robot.