• 한국생산제조학회지
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• 제22권3호
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• pp.421-428
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• 2013

The current vibration reduction methods for positioning systems lead to either complicated motion or the need for additional hardware when the positioning systems carry out frequent short-distance movements. This paper proposes a simple yet efficient vibration reduction method for positioning systems subjected to frequent short-distance movements. The essence of the proposed method is the trapezoidal or triangular velocity profiles, whose acceleration/deceleration rates are designed to be related to the natural frequency of concern. The combined use of the proposed method and the input shaping method is also proposed for the possible application to multi-mode systems. Experiments are performed to validate the proposed method. The simulation and experiments prove that the proposed method is of great use for residual vibration reduction in positioning systems subjected to frequent short-distance movement.

• 한국지진공학회논문집
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• 제18권5호
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• pp.221-230
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• 2014

The purpose of this study is to investigate the seismic performance of hollow RC bridge columns with reinforcement details for material quantity reduction. The proposed reinforcement details provide economy, are rational and shorthen the construction periods. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. Solution of the equations of motion is obtained by numerical integration using Hilber-Hughes-Taylor (HHT) algorithm. The adopted numerical method gives a realistic prediction of seismic performance throughout the input ground motions for several test specimens investigated. As a result, the proposed reinforcement details for material quantity reduction develop equal performance to that required for existing reinforcement details.

• 해양환경안전학회지
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• 제8권2호
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• pp.9-15
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• 2002

Ship operators use anchor dredging for the collision avoidance or safety of ship handling in a harbour or narrow channel. This paper clarifies the technique of the anchor dredging known as a common sense for. the seafarers A mathematical model at low speed range is established for the estimation of ship motion under the assumed environment, simulate the advance speed , and turning ability under the anchor dredging or not. The results shows good agreement with the conventional seamanship and their experiences as follows. Ahead speed used the anchor dredging is slower(speed reduction ratio:40%) than the normal ahead speed and the stopping distance is shorter (distance reduction ratio:40%)than the normal ahead distance without the anchor dredging.. Turning speed used anchor dredging is slower(speed reduction ratio:72%)than the normal ahead speed and the tactical diameter is shorter(distance reduction ratio:24%)than the diameter by the normal turning without the anchor dredging.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.59-68
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• 2005

In this study, we establish a theory for dynamic behaviors of an automatic ball balancer, analyze its dynamic characteristics, and provide its design guide line. Equations of motion are derived by using the polar coordinate system instead of the rectangular coordinate system which was previously used in other researches. After non-dimensionalization of the equations, the perturbation method is applied to locate the equilibrium positions and to obtain the linearized equations of motion around the equilibrium positions. The Eigenvalue problem is used to verify the dynamic stability around the equilibrium positions. On the other hand, the time responses are computed from the nonlinear equations of motion by using a time integration method.

• 한국정밀공학회지
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• 제21권1호
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• pp.116-123
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• 2004

The demand for the stable and comfortable cabin of a high speed passenger ship is increasing. The study on shipboard comfort has been mainly concentrated on the motion control of a whole hull body. In this study, however, a new control system operated by two parallel robots (3RPS, 3SPR) such as the active suspension system of motor vehicle is proposed. The goal of this control is keeping zero velocity of the upper robot (cabin) although the lower robot (ship) is moving by the waves. Jacobian matrix was used to design the controller, From the simulation results, the remarkable reduction of motion of the cabin (upper platform) was observed. The 3SPR parallel robot shows better performance compared to the 3RPS robot.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.41-45
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• 2001

This paper presents an implementation of motion control system of Switched Reluctance Motor (SRM) using digital hysteresis controller by TMS320F240 DSP. SRM position control system possess several advantages over other motors, including high efficiency, simple structure, low cost, and four-quadrant operation at a wide speed range, especially for the servo drive systems with precision, stability and fast response characteristics in the industrial applications. In the suggested motion control system, position control using digital hysteresis controller is developed, and is evaluated using experimental testing. The developed system for cost reduction and high-performance by fully digital controller is shown a good response characteristic of motion control results.

• ETRI Journal
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• 제25권5호
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• pp.297-304
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• 2003

A multimedia SoC often requires a large internal buffer, because it must store the whole search window to reduce the huge I/O bandwidth of motion estimation. However, the silicon area of the internal buffer increases tremendously as the search range becomes larger. This paper proposes a new method that greatly reduces the internal buffer size of a multimedia SoC while the computational cost, I/O bandwidth, and image quality do not change. In the proposed method, only the overlapped parts of search windows for consecutive macroblocks are stored in the internal buffer. The proposed method reduces the internal buffer. The proposed method reduces the internal buffer size to 1/5.0 and 1/8.8 when the search range is ${\pm}64{\times}{\pm}$64 and ${\pm}128{\times}{\pm}$128, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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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.

• 한국해양공학회지
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• 제27권1호
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• pp.31-36
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• 2013

In this paper, the effects of a foil attached to a ship on the ship motion, added resistance, and thrust generation in waves are analyzed. The unsteady theory for a two-dimensional foil is introduced to determine the coupled motion responses of the ship and foil. The thrust caused by the oscillating foil is evaluated and compared to the added resistance of the ship, so that a positive net thrust can be possible in waves. A comparison of the results of unsteady, quasi-steady, and experimental analyses is performed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.23-26
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• 2003

In this work. we propose an algorithm for detecting and compensating dynamic false contours in plasma display panels (PDPs). First, we detect the candidate pixels, which are likely to be corrupted by false contours, and merge those pixels into several regions. Second, we estimate the motion vectors of the selected regions. Finally, based on the motion information. we modify the luminance values of the pixels in the regions to alleviate the effects of false contours. Simulation results demonstrate that the proposed algorithm efficiently reduces dynamic false contours at low computational complexity.