• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2005년도 춘계학술발표회 및 정기총회 2권1호(통권2호)
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• pp.125-132
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• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and it happens large deformation phenomenon. And also there are highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore, in this study, to find the structural shape after large deformation caused by Initial stress, we need the shape analysis considering geometric nonlinear ten And the geodesic line on surface of initial equilibrium shape and the cutting pattern generation using the geodesic line is introduced.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.266-273
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• 1998

The object of this study is shape finding and cutting pattern generation of membrane structures under the following assumptions: (1) material is linearly elastic (2) stress state is plane stress. Cable and membrane structures should introduce the nonlinear analysis considering geometric nonlinearity because these structures deform largely under the external loads. The analysis procedure is consisted of three steps considering geometric nonlinearity unlike any other structures. First step is the shape finding analysis to determine the initial equilibrium shape. Second step is the stress-deformation analysis to investigate the behaviors of structures under various external loads. Once a satisfactory shape has been found, a cutting pattern based on the shape finding analysis may be generated from the view point of construction. In this paper, after shape finding analysis, cutting pattern determination procedure using weighted least-square minimization flattening method and some results are presented.

• 전기전자학회논문지
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• 제22권2호
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• pp.446-454
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• 2018

In this work, we summarize the calculation processes of obtaining a scattering factor using with the equilibrium average projection scheme (EAPS), with moderately weak coupling (MWC) interaction, and obtain the line-shape formula of an electron-deformation phonon interacting system interested in the confinement of electrons by squarwell confinement potentials in quantum two dimensional system.. Through the numerical analysis, we analysis the magnetic dependence of absorption power, P(B) in several temperature and frequency difference dependence of absorption power $P({\Delta}{\omega})$, in several external field, where ${\Delta}{\omega}={\omega}-{\omega}_0$ and ${\omega}({\omega}_0)$ is the angular frequency (the cyclotron resonance frequency). The result of equilibrium average projection scheme (EAPS) in SER-MWC explains the properties of quantum transition quite well.

• 로봇학회논문지
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• 제10권4호
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• pp.193-199
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• 2015

This paper dealt with a pincers-type gripper being able to grip a heavy-weighted cylindrical object having various size with itself. This gripper should be designed to seize the objects without any change of jaw shape. Grasping achieved equilibrium after the object slipped on the jaw while grasping it. To cope with this situation, we suggested the slip considered gripper design procedure based on grasping equilibrium. The obtained slip condition can provide a limit friction coefficient depending on the contact angle when initiating contact between jaw and object. Consequently, the gripping force and the required actuating force can be calculated. In order to verify the proposed slip condition, the simulations were performed using a dynamic software.

• 대한기계학회논문집
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• 제5권3호
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• pp.199-206
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• 1981

This paper presents a method of calculation of the stresses, the strains and the deflections due to welding in L shape and in T shape. Using step by step method of plasticity and establishing the equilibrium conditions in section, we calculated thermal stresses and strains during welding and in the final step of calculation we got the residual stresses, strains and the deflections due to welding. Also we measured the stresses and the strains with hole-drilling method and compared the results with the method of calculation presented in this paper. Because of its symmetry of section, the deflection due to welding in T shape is generally much less than that in L shape. The residual stresses are tensile in welded joints and HAZ, and compressive in base metal as butt welding of plates, but the compressive stresses in base metal decrease repidly as the points are away from welded joint except horizontal plates of T shape. The theoretical method of calculaiton presented in this paper coincides faily well with the experiment.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.1-4
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• 2000

This paper presents the analytical results of local - global interaction buckling of orthotropic I-shape compression members. Employing the equilibrium approach, the characteristic equation for local and global interaction buckling of I-shape compression member is derived. Using the derived equation, the buckling coefficients with respect to the ratio of length to width for the I-shape column are suggested as a graphical form. In addition, graphical forms of local, global and FEM results are presents, and they are compared with those in published document.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.775-784
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• 1997

A unified theory is presented for the shape analysis of curved surface with a single layer structure composed by frame, membrane or shell. The shapes produced by the theory have no shear stress in elements, and the stress states in the whole shape are as uniform as possible under an ordinary load. The theory starts from defining an element potential function expressed by the measurement of the element length or the element area. Therefore, the shape analysis can produce various forms according to the definition of the potential function, and each of those form or the cable net form with the potential function of the second power of element length is simply gotten by the linear analysis. The form in tensile stress is mechanically equal to an isotropic tension form.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.212-212
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• 2009

Nano composite sample were irradiated and annealed to study irradiation induced phase transformation behavior by nano indention technique. The specimens with 3mm in diameter were irradiatied. Polycrystalline nano filaments were broken their shape and tended to be equilibrium shape like facted sphere. The hardness of irradiatied nanocomposites was decreased by annealing which resulted from the grooving of silver filaments.

• 드라이브 ㆍ 컨트롤
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• 제17권2호
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• pp.28-37
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• 2020

It is difficult to analytically derive the relationship among volumetric displacement, flowrate, torque, and rotation speed regarding an instantaneous position of gerotor hydraulic pumps/motors. This can be explained by the geometric shape of the rotors, which is highly complicated. Herein, an analytical method for the instantaneous torque, rotation speed, flowrate, and volumetric displacement of a pump/motor is proposed. The method is based on two physical concepts: energy conservation and torque equilibrium. The instantaneous torque of a pump/motor shaft is determined for the posture of rotors from the torque equilibrium. If the torque equilibrium is combined with the energy conservation between the hydraulic energy of the pump/motor and the mechanical input/output energy, the formula for determining the instantaneous volumetric displacement and flowrate is derived. The numerical values of the instantaneous volumetric displacement, torque, rotation speed, and flowrate are calculated via the MATLAB software programs, and they are illustrated for the case in which inner and outer rotors rotate with respect to fixed axes. The degrees of torque fluctuation, speed fluctuation, and flowrate fluctuation can be observed from their instantaneous values. The proposed formula may provide a better understanding of the design or analysis process of gerotor pumps/motors.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.69-76
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• 2019

A stadium roof that uses the pin-jointed spatial truss system has to be designed by taking into account the unstable phenomenon due to the geometrical non-linearity of the long span. This phenomenon is mainly studied in the single-free-node model (SFN) or double-free-node model (DFN). Unlike the simple SFN model, the more complex DFN model has a higher order of characteristic equations, making analysis of the system's stability complicated. However, various symmetric conditions can allow limited analysis of these problems. Thus, this research looks at the stability of the DFN model which is assumed to be symmetric in shape, and its load and equilibrium state. Its governing system is expressed by nonlinear differential equations to show the double Duffing effect. To investigate the dynamic behavior and characteristics, we normalize the system of the model in terms of space and time. The equilibrium points of the system unloaded or symmetrically loaded are calculated exactly. Furthermore, the stability of these points via the roots of the characteristic equation of a Jacobian matrix are classified.