• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.142-149
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• 1995

This paper presents a new kinematic control strategy for serial redundant manipulators which gives repeatability in the joint space when the end-effector undergoes some general cyclic motions. Theoretical development has been accomplished by deriving a new inverse kinematic equation that is based on springs being conceptually located in the joints of the manipulator. Although some inverse kinematic equations for serial redundant manipulators have been derived by many researchers, the new strategy is the first to include the free angles of torsional springs and the free lengths of the translational springs. This is important because it ensures repeatability in the joint space of a serial redundant manipulator whose end-effector undergoes a cyclic type motion. Numerical verification for repeatability is done in terms of Lie Bracket Condition. Choices for the free angle and torsional stiffness of a joint (or the free length and translational stiffness) are made based upon the mechanical limits of the joints.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.158-164
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• 2000

In recent year, desire and request fer micro automation are growing rapidly covering the whole range of the industry. This has been caused mainly by request of more accurate manufacturing process due to a higher density of integrated circuits in semiconductor industry. This paper presents a six d.o.f fine motion stage using magnetic levitation technique, which is one of actuating techniques that have the potential for achieving such a micro motion. There is no limit in motion resolution theoretically that the magnetically levitated part over a fixed stator can realize. In addition, it Is possible to manipulate the position and the force of the moving part at the same time. Then, the magnetic levitation technique is chosen into the actuating method. However, we discuss issues of design, kinematics, dynamics, and control of the proposed system. And a few experimental results fur step input are given.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.691-700
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• 2000

A powerful analytical procedure and strain energy analysis to investigate the free vibration of antisymmetric angle-ply laminated plates, having one pair of opposite edges simply supported, are develped on the basis of the Yang, Norris and Stavsky (YSN) theory. The equation of motion of the plate are solved by the use of collocation method. A range of results are presented for plates to show the effects of modulus ratio and number of layers on natural frequency. In addition, an analysis of the strain energy distributions is used as an aid for the better understanding of the vibration characteristics of the plates.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.479-484
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• 2003

A non-contact 6D motion tracking system is proposed. The system consists of two color cameras, a color image grabber and a host computer, Motions of a floating vessel was measured by the constructed system. The instantaneous forces of the floating vessel are analyzed. The floating vessel was put on the water in a small water container in free conditions. The measured forces are reconstructed by the measurement results. The system can be used to non-contact measurements for 6D dynamic analysis of floating vessels.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.252-257
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• 1995

전자기력을 이용한 능동 진동제어는 1979년 Ellis 및 Mote가 원형 톱의 횡 진동의 감쇠에 관한 연구를 수행하였고, 1990년 Hong Su 및 T.S.Sankar등은 시스템의 절대 위치, 절대 속도 및 상대 위치 등의 제어 변수에 대하여 전자기 액튜에이터의 동적 특성이 진동 절연 성능에 미치는 영향에 관한 연구를 하였다. 본 연구는 상부질량과 하부질량이 스프링으로 연결된 2자유도 모델의 능동 진동제어에 대하여 이론해석과 실험해석을 수행하고 각각의 결과를 비교하였다. 실험모델은 직선운동 가이드에 설치된 2개의 질량과 하나의 전자기 액튜에이터를 이용하였다. 진동제어 방법으로서는 모우드 해석에 의한 제어, 스카이 훅 감쇠 제어, Viscous damping 제어 방법을 적용하였다. 본 연구의 목적은 이론해석 결과와 실험 결과를 비교하고 비슷한 제어효과에 대해서 에너지 소비가 작은 효율적인 제어방법을 찾는데 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.25-32
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• 1988

A formulation of an isoparametric quadrilateral higher-order plate bending finite element is presented. The 8-noded 28-d.o.f. plate element has been degenerated from the three-dimensional continuum by introducing the plate assumptions and considering higher-order in-plane displacement profile. The element characteristics have been derived by the Galerkin's weighted residual method and computed by using the selective reduced integration technique to avoid shear-locking phenomenon. Several numerical examples are given to demonstrate the accuracy and versatility of the proposed quadrilateral higher-order plate bending element over the other existing plate finite elements in both static and dynamic analyses.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.959-965
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• 1986

본 논문에서는 모듀울 로봇은 공장 자동화를 달성하기 위한 경제적인 방법으 로 기대되고 있다. 모듀울 로봇을 구성하는 모듀울을 개발 설계하기 위해서는 먼저 유용한 로봇을 기본 구조를 연구하여야 한다. 일반적으로 로봇의 처음 3개의 관절은 로봇 손의 위치를 결정하는 데 쓰이고 나머지 관절은 로(positional maneuverability matrix)과 방향기동행열로 구성됨음을 보이고, 가분성(separability)의 조건을 제시하 였다.또한 희전관절이나 미끄름관절로 이루어진 3자유도 로봇 팔의 3차원 공간에서 의 기본형태는 12개임을 밝히고, 3자유도 손목이 3개 방향을 완전히 조정할 수 있기 위해서는 3개의 회전관절축이 서로 직교하여야 함을 보였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.727-730
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• 2011

본 논문에서는 3차원 자기부상열차에 대한 열차-가이드웨이 상호작용 해석기법을 제시하고자 한다. 수직 및 수평방향 변위, 피칭, 롤링 그리고 요잉에 대한 자유도를 각 보기와 차체에 대해 고려하여 총 25자 유도 자기부상열차에 대한 운동방정식을 유도하였다. 제어방식으로는 UTM01에 적용된 제어기법을 이용하였고, 궤도 틀림을 고려하기 위하여 미국 FRA에 적용하고 있는 궤도 불규칙성에 대한 밀도 스펙트럼 함수를 이용하여 조도를 생성하였다. 같은 조건하에 2차원 모델과 3차원 모델의 동적응답 결과를 비교하여 타당성을 확인하였고, 2차원 모델에서 고려할 수 없는 수평방향 조도를 도입하였을 때 수직방향 부상공극에는 두드러진 영향을 미치지 않았으나, 수평방향 부상변위에 있어서 중요하게 작용함을 확인하였다.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.251-256
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• 1999

Viscosities of toluene were experimentally determined by the falling-ball method at several temperatures and pressures to investigate the pressure and temperature dependence of the viscosity of toluene. With the shear stress of the viscous flow of toluene, the shear free energy, the shear entropy, and the shear enthalpy were defined to discuss the variations of the shear thermodynamic properties with pressure. The effect of temperature and pressure on the shear thermodynamic properties obtained experimentally can be explained by means of the molecular thermal agitation due to temperature incleasing and the steric effect of the closed molecules of to Iuene due to pressure elevation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2297-2307
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• 1995

An experimental study on the structure of a separated shear layer downstream of the backward-facing step has been performed by examining mean flow and turbulent quantities in terms of free stream turbulence. When free stream turbulence exists, the entrainment rate of the separated shear layer and the flow rate in the recirculation region are enhanced, resulting in shorter reattachment length. The production and diffusion terms in the turbulent kinetic energy balance are shown to increase more than the dissipation term does. Rapid decrease of the pressure-strain term in the shear stress balance implies the enhancement of the three-dimensional motion by free stream turbulence.