• Journal of the Korean Society for Railway
• /
• v.12 no.2
• /
• pp.236-242
• /
• 2009

This paper presents a numerical analysis method to determine flange contact at variable wheel positions. The shapes of the wheel and rail surface functions with surface parameters. The Newton-Rhapson method for wheel-rail contact can provide fast solutions, but may not yield true values at optimization process with the condition that minimum distance is zero can time-consuming. A compound method, combining the Newton-Rhapson methods the optimization process method is proposed to provide exact solutions efficiently.

• Journal of Navigation and Port Research
• /
• v.33 no.6
• /
• pp.457-462
• /
• 2009

In this paper we suggest optimal positioning algorithm for DER(distributed energy resource)s near ocean side by using Newton-Rhapson load flow calculation. By installing DERs within urban area, electric power can be effectively transmitted to each loads without constructing additional large scale power stations and transmission lines. Therefore, DERs have attracted worldwide attention as urban area energy sources. However, there are quite a few studies for estimation of power loss due to DERs' location change within urban area Hence, in this study, an optimal positioning scheme for DERs is proposed in order to minimizing electrical power loss.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.2 no.2
• /
• pp.29-38
• /
• 1982

Nonlinear hydrological model containing the nonlinearity of effective rainfall, lag time and runoff is presented. In the evaluation of rainfall excess, the polynomial fitting method for total rainfall, 5 day antecedant rainfall and direct runoff is developed. In the application to actual watershed, the estimated model parameters of nonlinear lag model reflecting the nonlinearity of lag time are compared with the parameters, by both the fitting method and the correlation, model which are the modified version of the storage function model. The Successive Approximation Method in mathematical solution and Newton-Rhapson method in numerical solution are found to be superior to the conventional numerical graphic method in the analysis of nonlinear processes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.387-391
• /
• 2009

The experimental study on the ducted fan for the propulsion system of a small UAV has been performed. In this paper, to investigate the three-dimensional unsteady flow field characteristics of the ducted fan, it was measured by using a $45^{\circ}$ inclined hot-wire from hub to tip at inlet, behind the rotor and outlet of the ducted fan. The hot-wire signal data was acquired at fixed yaw angle. The data was averaged by using the PLEAT (Phase Locked Ensemble Averaging Technique), and then three of non-linear equations were solved simultaneously by using the Newton-Rhapson numerical method. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential contour plot.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1994.04a
• /
• pp.57-64
• /
• 1994

The purpose of this paper is to find minimum surface shape of pneumatic structure using the finite element method. The pneumatic membrane structure is a kind of large deformation problem and very flexible composite material, which mean geomatric nonlinearity. It is not to resist for compression and resultant moment. As the displacement due to internal pressure is getting bigger, it should be considered the direction of forces. It becomes non-linear problem with the non-conservative force. The follower-force depends on the deformation and the direction of force is normal to each element. The solution process is obtained the new stiffness matrix (load correction matrix) depending on deformation through each iterated step. However, the stiffness matrix have not the symmetry and influence on the time of covergence. So in this paper Newton-Rhapson method for solving non-linear problem and for using symmetic matrix, the load direction is changed in each iterated step using the transformation matrix.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.894-899
• /
• 2000

An automatic mesh generation system with unstructured quadrilateral elements on trimmed NURBS surfaces has been developed.. In this paper, NURBS surface geometries in the IGES format have been used to represent model shape. NURBS surface is represented as parametric surface. So each surface could be mapped to a 2D parametric plane through the parametric domain. And then meshes with quadrilateral elements are constructed in this plane. Finally, the constructed meshes are mapped back to the original 3D surface through the parametric domain. In this paper, projection plane, quasi-expanded plane and parametric Plane are used as 2D mesh generation plane. For mapping 3D surface to parametric domain, Newton-Rhapson Method is employed. For unstructured mesh generation with quadrilateral elements on 2D plane, a domain decomposition algorithm using loop operators has been employed. Sample meshes are represented to demonstrate the effectiveness of the proposed algorithm.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.2
• /
• pp.97-102
• /
• 2017

A current transformer (CT) is a type of sensor that consists of a combination of electric and magnetic circuits, and it measures large ac currents. When a large amount of current flows into the primary winding, the alternating magnetic flux in the iron core induces an electromotive force in the secondary winding. The characteristics of a CT are determined by the iron core design because the iron core is saturated above a certain magnetic flux density. In particular, when a large current, such as a current surge, is input into a CT, the iron core becomes saturated and the induced electromotive force in the secondary winding fluctuates severely. Under these conditions, the CT no longer functions as a sensor. In this study, the characteristics of the secondary winding were investigated using the time-difference finite element method when a current surge was provided as an input. The CT was modeled as a two-dimensional analysis object using constraints, and the saturation characteristics of the iron core were evaluated using the Newton-Rhapson method. The results of the calculation were compared with the experimental data. The results of this study will prove useful in the designs of the iron core and the windings of CTs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.395-398
• /
• 2009

Currently, a new generation of ducted fan UAVs (Unmanned Aerial Vehicles) is under development for a wide range of inspection, investigation and combat missions as well as for a variety of civil roles like traffic monitoring, meteorological studies, hazard mitigation etc. The current study presents extensive results obtained experimentally in order to investigate the tip clearance effects on performance characteristics of a ducted fan for small UAV systems. Three ducted fans having different tip clearance gap and with same rotor size were examined under three different yawed conditions of calibrated slanted hot-wire probe. Three dimensional velocity flow fields were measured from hub to tip at outlet of the ducted fan. The analysis of data were done by PLEAT (Phase locked Ensemble Averaging Technique) and three non-linear differential equations were solved simultaneously by using Newton -Rhapson numerical method. Flow field characteristics such as tip vortex and secondary flow were confirmed through axial, radial and tangential velocity contour plots. At the same time, the effects of tip clearance on axial thrust and input power were also investigated by using wind tunnel measurement system. For enhancing the performance of ducted fan, tip clearance level should be as small as possible.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.06a
• /
• pp.287-288
• /
• 2009

In this paper we developed positioning algorithm considering distributed energy resource of ocean side by load flow calculation using Newton-Rhapson method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.2 s.173
• /
• pp.329-337
• /
• 2000

An investigation has been performed to develop an analysis tool based on a nonlinear beam theory, which can be used to predict the long-term behavior of an artificial hip joint. The nonlinear behav ior of the femur arise from the coupled dependence of the bone density and the mechanical properties on each other. The beam theory together with its numerical algorithm is developed to take into account the nonlinear bone remodeling process of the femur that is long enough to be assumed as a beam. A piecewise linear curve for the bone remodeling rate is used in the bone remodeling theory and the surface area density of bone is modeled as the third order polynomial function of bone density. At each section of the beam, a constant curvature is assumed and the longitudinal strains are also assumed to vary linearly across the section. The Newton-Rhapson iteration method is used to solve the nonlinear equations for each cross section of the bone and a backward method is used to march along the time. The density and the remodeling signal ar, calculated along with time for the various time steps, and the developed beam theory has been verified by comparing with the results of finite element analysis of a remodeling bone with an artificial hip joint of titanium prosthesis subjected to uni-axial loads and pure bending moment. It is concluded that the developed beam theory can be used to predict the long-term behavior of the femur and thus to design the artificial hip prosthesis.