• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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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.

• 한국정밀공학회지
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• 제20권4호
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• pp.49-58
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• 2003

In this study, the equation of motion of impacting elastic structures was derived through the theory, and the shape control of impact force using correlations of the dynamic characteristics and impact force history between two elastic structures was accomplished. Through numerical analysis and experiments, the classical contact mechanisms were verified, and the effects of the relative motion between impactor and elastic structure on the impact force shape were studied, and then the shape change of impact force depending on the impact position and mode shape of cantilever beam were analyzed. The 2-DOF impactor was designed and used. Reconstruction characteristics of impact force in cantilever beam were reviewed .

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.920-924
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• 2002

This paper presents the reverse design of a cam mechanism using NURBS(Nonuniform Rational B-spline curve). Cam is very difficult to make the accurate shape on the design and the manufacture. Because the cam shape is commonly made in order to move in special functions. The reverse design can be used to check accuracy between the designed data and the manufactured data of the cam shape and also reproduce the cam without the design data. The reverse design procedures consist of motion analysis and curve fitting. The motion analysis is used the central difference method and the relative velocity method to find the displacement and velocity. The curve fitting is used NURBS to develope the whole curve. The central difference method is derived in the 3 dimensional space.

• 대한기계학회논문집
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• 제18권8호
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• pp.1974-1984
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• 1994

This paper presents a relative coordinate formulation for constrained mechanical systems. Relative coordinates are defined along degrees of freedom of a joint. Graph theoretic analyses are performed to identify topological paths in mechanical systems. Cut constraints are generated to handle closed loop systems. Equations of motion are derived in the Cartesian space and transformed to the joint space. Relative generalized coordinates are corrected to satisfy the cut constraints by a parametrizatiom method.

• 한국항공우주학회지
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• 제33권1호
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• pp.39-47
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• 2005

본 논문에서는 정지궤도 위성의 상대 운동과 최적화 기법과의 결합을 통해 새로운 형태의 위치유지 기법을 제안하였다. 상대 궤도 운동을 나타내기 위해 궤도 압축방법을 이용하여 비선형 미분 방정식 형태가 아닌 닫힌 해 형태의 모델을 사용하였으며, 매우 정확한 궤도 전파가 가능함을 확인하였다. 기존의 위치유지 기법은 궤도 요소를 이용하여 목표 궤도를 획득함으로써 궤도 형상을 유지하지만, 본 논문에서는 정밀한 위치유지를 위해 위성의 상대 위치를 직접 제어하였다. 최적화 목적 함수의 설정을 통해 다양한 형태의 기동 전략을 수립하였고, 구속 함수를 이용하여 상황에 따른 위치유지 범위를 설정하였다. 이 방법은 최적화 함수의 변경을 통해 다양한 위치유지 기법을 쉽게 적용할 수 있고, 그에 따른 궤도 운동을 분석할 수 있다. 비선형 시뮬레이션을 통해 위성의 위치가 허용범위 내에 적절하게 유지되고 있음을 확인하였다.

• 한국기계가공학회지
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• 제8권1호
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• pp.77-82
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• 2009

This paper reports a kinematic analysis and experimental results for the polishing process of G7 LCD glass. A kinematic analysis for the relative motion of the upper plate and lower plate has been done and computer simulation has been programmed. A series of polishing experiments has also been carried out and compared with analytical data. The experimental results agreed well with analytical ones. The experimental results indicate that the polishing removal is proportional to the relative speed and pressure.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.355-368
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• 2002

In this paper, we address the numerical investigation on the effect of liquid compressibility onto the natural frequency of liquid-filled containers. Traditionally the liquid motion has been treated as an ideal fluid motion. However, from the numerical experiments for the axisymmetrical free-vibration of cylindrical liquid-storage tanks, we found that the relative difference in natural frequencies between ideal and compressible motions becomes remarkable, as the slenderness of tank or the relative liquid-fill height becomes larger. Therefore, in such cases of dynamic systems, the liquid compressibility becomes an important parameter, for the accurate vibration analysis. For the free-vibration analysis of compressible liquid-structure interaction we employed the coupled finite element formulation expressed in terms of the acoustic wave pressure and the structure deformation.

• 한국전산유체공학회지
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• 제21권3호
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• pp.31-38
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• 2016

The FDS-HCIB method is expanded to simulate water-oil-air flows around oil booms under relative motion, which is intended to increase the thickness of contained oil. The FDS scheme captures discontinuity in the density field and abrupt change of the tangential velocity across an interface without smearing. The HCIB method handles relative motions of thin oil booms with ease. To validate the developed FDS-HCIB code for water-oil-air flow around a moving body, the computed results are compared with the reported experimental results on the shape, length, and thickness of the oil slicks under towing. It is observed that the increase in pressure field between two barriers lifts the oil slick and the interfacial wave propagates and reflects as one barrier gets closer to the other barrier.

• 연구논문집
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• 통권33호
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• pp.89-97
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• 2003

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then detemines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower. Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents shape design of the barrel cam in order to prove the accuracy of the proposed methods

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.1-8
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• 2003

In this paper, an observer-based adaptive controller is proposed to control the longitudinal motion of vehicles. The standard gradient method is used to estimate the vehicle parameters, mass, time constant, etc. The inter-vehicle spacing and its derivatives are estimated by using the sliding mode cascade observer introduced in this paper. It is shown that the proposed adaptive controller is uniformly ultimately bounded. It is also shown that the errors of the relative distance, the relative velocity and the relative acceleration asymptotically converge to zero. The simulation results are presented to investigate the effectiveness of the proposed method.