• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1005-1016
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• 2002

In this paper, a 2 GHz tapered shape of multiport power divider/combiner modified from the model published by [10] and adopted PBG(Photonic Band Gap) structure is proposed. Parameters determining electrical property of the circuit structure have been analyzed by HFSS simulation. For input matching, balance of output signals and phase linearity at each output port, one circular hole has been etched out on the circuit surface. 1:2 and 1:3 power dividers/combiners designed by this study have been compared with the same circuits designed by the method of [10] in terms of S-parameters. As a result, it has been found that tile modified structure and PBG of power divider/combiner have improved return loss more than 20 dB and another 18 dB. respectively, at 2 GHz.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.585-590
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• 2002

Abrasive water-jet(AWJ) machining is a new cutting technology. The AWJ can cut various materials touch as metal, glass and stone. However, the AWJ machining makes troubles including kerf, rounding and side taper. In this study, we investigated the correlation between parameters of abrasive water-jet machining arid cutting characteristics. The machining parameter were the material thickness and the traverse speed. The experiment was conducted to cut the stainless steel(STS41) and the mild steel(SS41) specimens. The results of the experiment weirs presented as the relation between cutting conditions and trouble of a dimension error, a conner error, an uncut width and a kerf.

• Structural Engineering and Mechanics
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• v.45 no.1
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• pp.69-93
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• 2013

The present study deals with the dynamics of the flapwise (out-of-plane) vibrations of a rotating, internally damped (Kelvin-Voigt model) tapered Bernoulli-Euler beam carrying a heavy tip mass. The centroid of the tip mass is offset from the free end of the beam and is located along its extended axis. The equation of motion and the corresponding boundary conditions are derived via the Hamilton's Principle, leading to a differential eigenvalue problem. Afterwards, this eigenvalue problem is solved by using Frobenius Method of solution in power series. The resulting characteristic equation is then solved numerically. The numerical results are tabulated for a variety of nondimensional rotational speed, tip mass, tip mass offset, mass moment of inertia, internal damping parameter, hub radius and taper ratio. These are compared with the results of a conventional finite element modeling as well, and excellent agreement is obtained.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.137-144
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• 1999

The finite element method was adopted to find out the natural frequencies of a sinusoidally tapered beam with simply supported boundary conditions. The parameters considered in the numerical analysis are the taper parameter, $\alpha$ ($\alpha$=0.0, 0.1, ~ , 2.0) and the sectional property parameters, m and n [(m, n):(0, 2), (1, 3), (2, 4)]. It is generally known that the results of the numerical analysis corresponding to each pair of sectional property parameters, (m, n) are represented by second order polynominals of $\alpha$ . The coefficients of a in the polynominals are determined by using the regression technique, which reveals small m in most cases of given sectional property parameters (m, n).

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.315-320
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• 2000

The optimal design for the shape of metal ring obturator under the high pressure using parameter study on the stress analysis considering effects of design variable is presented and is compared to experimental results. The design variables are such as thickness, taper, radius of shape of the obturation ring. For optimization of the obturation ring, the weight is maximized subject to maximum stress of the obturator within allowable stress. The design constraints are geometric elements of design variables. The trends of parametric study are in good agreement with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.919-928
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• 2010

Four patterns for width adjustment were studied with an aim to increase the width-adjustment speed in continuous casting. The main goals are to minimize the actuating force of a WAM actuator, to develop a deformation analysis model of a solidified shell in the mold, and to induce the main limit factor for the speedup of width adjustment. On the basis of the width-adjustment experiment, the notable features of four patterns types were considered, and we compared the corresponding actuating forces. For comparing the driving forces of the patterns, during the experiment, the same casting speed was maintained for each pattern. To optimize the parameter of the deformation analysis model of the solidified shell, the experiment results were applied to them. To speed up width adjustment and to reduce the driving force, we controlled the pattern parameters. The most effective pattern was the fast-mode pattern, and the taper was the main parameter that helped reduce the driving forces during the motion of the actuator.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.3
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• pp.1-5
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• 2005

There are two types of solenoid actuator for force and position control of the fluid power system. One is an on-off solenoid actuator and the other is an electro-magnetic proportional actuator. They have some different characteristics for attraction force according to solenoid shape. Attraction force of the on-off solenoid actuator only depends on flux density. And the stroke-force characteristics of the proportional solenoid actuator are determined by the shape of the control cone. In this paper, steady state characteristics of the solenoid actuator for electro-hydraulic proportional valve determined by the shape of control cone are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attractive force in the control region independently on the stroke position. And the shape of control cone is optimized using 1+1 evolution strategy to get a constant force. In the optimization algorithm, control cone length, thickness and taper length are used as a design parameter.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.275-283
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• 2021

A parametric study was conducted on the effects of five fundamental design parameters on springback, including die clearance, step height, step width, punch radius, and taper relief in an L-bending process, controlled by the compression force. The experiment was also conducted to verify the usefulness of the parametric study procedure for process design, as well as the finite element predictions. The elastoplastic finite element method was utilized. The L-bending process of the york product, which is a key part of the breaker mechanism, was employed. The deformation of the material was assumed to be due to plane strain. Five samples of each design parameter were selected based on experiences in terms of process design. The finite element predictions were analyzed in detail to show a shortcut towards the process design improvement which can replace the traditional process design procedure relying on trial-and-errors. The improved process design was verified to meet all the requirements and the predictions and experiments were in good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1059-1068
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• 2016

This paper proposes slow wave structure(SWS) utilized to increase antenna gain of printed dipole antenna(PDA) and to suppress sidelobe level simultaneously, and makes sure of electrical characteristics of the antenna according to parameter variations of components of the slow wave structure. The printed slow wave structure which is composed of a dielectric substrate and a metal rods array is located on excited direction of the PDA, affecting the radiation pattern and its intensity. Parasitic elements of the metal rods are arrayed in narrow consistent gap and have a tendency to gradually decrease in length. In this paper, array interval, element length, and taper angle are selected as the parameter of the parasitic element that effects radiation characteristics. Magnitude and phase distribution of the electrical field are observed and analyzed for each parameter variations. On the basis of these results, while the radiation pattern is analyzed, array methods of parasitic elements of the SWS for high gain characteristics are provided. The proposed antenna is designed to be operated at the Wifi band(5.15~5.85 GHz), and parameters of the parasitic element are optimized to maximize antenna gain and suppress sidelobe. Simulated and measured results of the fabricated antenna show that it has wide bandwidth, high efficiency, high gain, and low sidelobe level.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.357-365
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• 2011

The current trends in steel construction intend to use tapered sections to minimize as much as possible the use of excess material. This can be done by choosing the cross-sections to be as economical as possible, leaving the classical approach of using prismatic members. In addition, it is important to predict the buckling behavior of tapered member with large depth-to-thickness ratio in order to prevent the collapse of PEB system subjected to overloads. An experimental investigation of buckling behavior of tapered beam was presented. The primary test parameter was depth-to-thickness ratio and taper ratio. Using initial stiffness and load-carrying capacity proposed by current provision, the simple plastic hinge method using modified Yoda's model and finite element analysis, the prediction of a moment-rotation curve of linearly tapered member was presented. Moreover, comparisons between analytical and experimental data for moment-rotation curves were accomplished.