• 한국자동차공학회논문집
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• 제14권6호
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• pp.160-170
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• 2006

If hydraulic pump controlled by mechanical type regulator has more than one control function, the construction of regulator will be very complicated and control performance falls drastically. It is difficult to have more than one control function for hydraulic pump controlled by electronic type hydraulic valve due to the inconsistency of controllers. This paper proposes a multi-function control technique which controls continuously flow, pressure and power by using EPPR(Electronic Proportional Pressure Reducing) valve in swash plate type axial piston pump. Nonlinear mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. A reaction spring is installed in servo cylinder to secure the stability of the control system. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

• Structural Engineering and Mechanics
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• 제88권6호
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• pp.589-598
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• 2023

This article addresses the quasi-static analysis of time-dependent honeycomb sandwich plates with various geometrical properties based on the bending analysis of elastic honeycomb sandwich plates employing a time function with three unknown coefficients. The novel point of the developed method is that the responses of viscoelastic honeycomb sandwich plates under static transversal loads are clearly formulated in the space and time domains with very low computational costs. The mechanical properties of the sandwich plates are supposed to be elastic for the faces and viscoelastic honeycomb cells for the core. The Boltzmann superposition integral with the constant bulk modulus is used for modeling the viscoelastic material. The shear effect is expressed using the first-order shear deformation theory. The displacement field is predicted by the product of a determinate geometrical function and an indeterminate time function. The simple HP cloud mesh-free method is utilized for discretizing the equations in the space domain. Two coefficients of the time function are extracted by answering the equilibrium equation at two asymptotic times. And the last coefficient is easily determined by solving the first-order linear equation. Numerical results are presented to consider the effects of geometrical properties on the displacement history of viscoelastic honeycomb sandwich plates.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.237-240
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• 2000

A new control method using average comparison strategy have been proposed in this paper. This control method realizes sinusoidal input and output current. unity input displacement factor regardless of load power factor. Moreover compensation of the asymmetrical and harmonic containing input voltage is sautomatically realized and calculation time of control function is reduced.

• Journal of Mechanical Science and Technology
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• 제15권2호
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• pp.225-231
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• 2001

A mathematical model for the analysis of roll gap phenomena in the strip temper rolling process is described. A new approach to solve the roll indentation and diverging problem in modeling of severe temper rolling cases is obtained by adopting the preliminary displacement principle of two contacted rough bodies to describe the friction behavior in the roll gap. The mechanical peculiarities of the temper rolling process, such as a high friction value with high roughness rolls and a non-circular contact arc, low reduction and non-negligible entry and exit elastic zones as well as central preliminary displacement zone etc., are all taken into account. The deformation of work rolls is calculated with the influence function method and an arbitrary contact are shape is permitted. The strip deformation is modeled by the slab method and the entry and exit elastic deformation zones are included. The preliminary displacement principle is used to determine the boundaries and to calculate the friction of the central preliminary displacement zone. The model is calibrated against the production mill data and installed in the setup computer of a temper rolling mill in POSCO. The validity and precision of the model have been proven through a comparison of the measured roll forces and the predicted ones.

• 한국정밀공학회지
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• 제25권1호
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• pp.79-84
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• 2008

For the precision measurement of industrial products, the location of holes inside the products, if they exist, are often selected as feature points. The measurement of hole location would be performed by vision and laser-vision sensor. However, the usage of those sensors is limited in case of big change of light intensity and reflective shiny surface of the products. In order to overcome the difficulties, we have developed a hole displacement measuring device using contact-type displacement sensors (LVDTs). The developed measurement device attached to a robot measures small displacement of a hole by allowing its X-Y movement due to the contact forces between the hole and its own circular cone. The developed device consists of three plates which are connected in series for its own function. The first plate is used for the attachment to an industrial robot with ball-bush joints and springs. The second and third plates allow X-Y direction as LM guides. The bottom of the third plate is designed that various circular cones can be easily attached according to the shape of the hole. The developed system was implemented for its effectiveness that its measurement accuracy is less than 0.05mm.

• 대한기계학회논문집A
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• 제28권10호
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• pp.1500-1508
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• 2004

Stress and displacement fields for a crack propagating along interface between isotropic material and functionally gradient one with linear property gradation along X direction are developed. The stress and displacement fields are obtained from the complex function of steady plane motion for isotropic and functionally gradient material (FGM). The stresses and displacement in isotropic material of bimaterial are not influenced by nonhomogeneity, however, the fields in FCM are influenced by nonhomogeneity in the terms of higher order, n$\geq$3. When the nonhomogeneous parameter in FGM is zero, or in area close to crack tip, the fields are identical to those of isotropic-isotropic bimaterial. Using these stress components, the effects of nonhomogeneity on stresses are discussed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.281-288
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• 2000

In this study, we tried to determine failure criteria for joints of soft rock using ring shear test machine. The residual stress fellowing shear behavior was determined by the result of ring shear test and direct shear test. Ring shear test with the specimens which cover a large deformation range was adapted to measure a residual stress, and was possible to present the peak stress to present the peak stress to the residual stress at the same time. Residual stress is defined a minimal stress of specimens with a large displacement and the result of the peak residual stress is shown by a size of displacement volume. Therefore, the residual stress in soil was decided by shear stress of maximum shear stress - shear displacement(angle) based on the test result of a hyperbolic function ((equation omitted), a, b ＝ experimental constant). In this study, it was proved that the residual stress of rock joint can be determined by using of this method.

• 대한정형도수물리치료학회지
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• 제1권1호
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• pp.49-63
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• 1995

Examination at the spine is dependent on assessment of function. At all spine levels a number of general anatomical considerations hold sway which together dictate the format of the evaluation. Because disc lesions are common and generally responsive to treatment, the examination sets out to differentiate between disc lesions and the other sources of pain as well as establishing the particular treatment that will benefit any given displacement. As elsewhere in the body, displacements give rise to certain characteristic symtoms and signs. First, the history is indicative. Second, any loose fragment in the joint restricts spinal movement in some but not all directions, producing the non-capsular pattern characteristic of internal derangement. Third, a displacement protruding posteriorly interferes with the dura mater ; apart from pain, this adversely affects the dura's normal painless mobility. Fourth, a displacement protruding laterally connects with the appropriate nerve root emerging from the dura mater. Finally, compression of the spinal cord strongly contraindicates manipulation, the primary treatment for cartilaginous displacements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1-4
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• 1996

It is difficult that a non-translational motion in a block is estimated by the block matching algorithm (BMA). In this paper, a nodal-displacement-based deformation model is used for this reason. This model assumes that a selected number of control nodes move freely in a block and that displacement of any interior point can be interpolated from nodal displacements. As a special case with a single node this model is equivalent to a translational model. And this model can represent more complex deformation using more nodes. We used an iterative gradient based search algorithm to estimate nodal displacement. Each iteration involves the solution of a simple linear equation. This method is called the deformable block matching algorithm (DBMA).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.105.1-105
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• 2001

In this paper, a technique is described for classifying normal cases and abnormal cases in automatic spinal deformity detection by computer based on moire topographic images of human backs. Displacement is evaluated statistically between the middle line extracted from the entire moire image and the middle line obtained from a small rectangle area defined on the moire image. The middle line is calculated employing a developed potential symmetry analysis technique. The displacement is calculated in several regions and the mean and the standard deviation of the displacement values are chosen as two features. A linear discriminant function (LDF) is defined on the 2-D feature space based on the Mahalanobis distance and the features are classified into two categories, i.e., normal and ...