• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.265-271
• /
• 1997

A bond graph modeling approach which is equivalent to a finite element method is formulated in the case of the piezoelectric thickness vibrator. This formulation suggests a new definition of the generalized displacements for a continuous system as well as the piezoelectric thickness vibrator. The newly defined coordinates are illustrated to be easily interpreted physically and easily used in analysis of the system performance. Compared to the Mason equivalent circuit model, the bond graph model offers the primary advantage of physical realizability. Compared to circuit models based on standard discrete electrical elements, the main advantage of the bond graph model is a greater physical accuracy because of the use of multiport energic elements. While results are presented here for the thickness vibrator, the modeling method presented is general in scope and can be applied to arbitrary physical systems.

• Journal of electromagnetic engineering and science
• /
• v.10 no.3
• /
• pp.127-131
• /
• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside a conducting screen of finite thickness has been considered in the case that the transverse electric(to the slit axis) polarized plane wave is incident on a slit. The problem is solved numerically by the method of moments and the results are compared with those obtained from an equivalent circuit suitable for a case in which the slit width is infinite and the structure is modified to the two partially overlapped conducting planes. It is observed that when the cavity is resonated, the effective slit width reaches its maximum value of $1/\pi$ wavelengths, irrespective of the actual slit width and the incidence angle. When the thickness of the conducting plane is much smaller than the wavelength, the numerical results for the effective slit width(or transmission width) agree well with those obtained from the equivalent circuit, even though the slit is as narrow as the thickness of the conducting plane.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1394-1397
• /
• 2005

The object of this study was to design of micro stage, which is one of the equipments embodied in ultra precision positioning mechanism. Design factors for micro stage were decided a roundness of hinge, a thickness of hinge, a thickness of stage, a length of arms and a clearance of division. To obtain the $1^{st}$ natural frequency and equivalent stresses, FEM simulation was performed using the table of orthogonal arrays and Taguchi method was used to determine the optimal design parameters. As results of this study, the size of 1st natural frequency and equivalent stresses on micro stage was influenced significantly by a thickness of hinge and a length of arm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.359-360
• /
• 2009

In this study, we propose a practical method to improve the clarity and the period of the beat in a Korean bell. Proper beating in vibration and sound is very important feature in Korean bell. An equivalent ring theory is applied and finite element analysis is performed to determine the condition of the asymmetry of the bell. The clearity and the period of the beat are improved by attaching a counter mass or decreasing local thickness. This paper shows that the improved the attaching a counter mass or decreasing local thickness. This paper of the beat are improved by attaching a counter mass or decreasing local thickness. This paper shows that the amount and position of the local variation for the required beat condition can be predicted by using the equivalent model, The predicted results are verified by the experiment.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.464-468
• /
• 2008

In most of the passenger side airbag door in hard type IP today is designed with invisible tear-seam line. In order to design the tear-seam invisible, the tear-seam must be designed with required RWT (residual wall thickness) that is just thick enough to be broken by the PAB pressure on deployment and not by other surrounding impact forces. Hence, keeping the right optimum opening force is very important, and finding the right RWT became the key in designing the tear-seam. The study conducted in this paper describes the search for the optimum RWT around the tear-seam by using finite element method and the optimum RWT is suggested for milling type tear-seam having V-shape cross-section.

• Imaging Science in Dentistry
• /
• v.32 no.3
• /
• pp.135-139
• /
• 2002

Purpose: To determine the proper reference step wedge for digital Cu-Equivalent Image analyzing systems for measurement of bone density. Meterials and Methods : Radiograms of lumbar vertebrae phantom (1g/㎠) with 3 test copper step wedges of 0.03, 0.05 and, 0.1 mm thickness unit were taken and analyzed using NIH image software on a Macintosh personal computer. Measured densities of the lumbar areas in the Cu-Equivalent images made by utilizing 3 different copper stepwedges were compared with a known bone density. Results: The values of r2 for all copper equivalent images were over 0.99. The mean Cu-Eq value of lumbar in copper equivalent image made by a 0.1 mm copper stepwedge was 0.22 ± 0.06 mm and converted to hydroxyapatite density of 1.03 g/㎠. The stepwedges of 0.03 and 0.05 mm produced results having higher values than the actual known bone density. They did not show the blue and green color level that appeared in lumbar on color enhanced image. Conclusion : A copper stepwedge of adequate thickness and range of steps which can express the range of density of bone being measured should be used.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1094-1102
• /
• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside conducting screen of finite thickness is considered for the case that the TE(to the slit axis) polarized plane wave is incident on the slit in conducting screen. Using the method of moments the variations of the transmitted power through the slits are obtained and compared with those computed from an equivalent circuit constructed using an equivalent slit admittance. It is found that the effective slit width of a narrow slit, at resonance, becomes $1/{\pi}$ wavelengths independently of the actual slit width. The transmission resonance phenomena in the proposed geometry are explained in connection with the variations of an equivalent admittance of the slit in the cavity.

• Proceedings of the Optical Society of Korea Conference
• /
• 1989.02a
• /
• pp.225-229
• /
• 1989

Taking the normal mode transmission direction perpendicular to the substrate, an alternative equivalent network formulation is developed for the analysis of optical strip waveguides. All kinds of mode couplings between the normal modes are included in this formulation. Compared to the previous equivalent network formulations, the calculations are simplified especially when the thickness of the uniform slab is thin enough such that no well guided modes are available along the uniform slab waveguide.

• Structural Engineering and Mechanics
• /
• v.51 no.5
• /
• pp.867-891
• /
• 2014

An equivalent single layer trigonometric shear deformation theory taking into account transverse shear deformation effect as well as transverse normal strain effect is presented for static flexure of cross-ply laminated composite and sandwich plates. The inplane displacement field uses sinusoidal function in terms of thickness coordinate to include the transverse shear deformation effect. The cosine function in thickness coordinate is used in transverse displacement to include the effect of transverse normal strain. The kinematics of the present theory is much richer than those of the other higher order shear deformation theories, because if the trigonometric term (involving thickness coordinate z) is expanded in power series, the kinematics of higher order theories (which are usually obtained by power series in thickness coordinate z) are implicitly taken into account to good deal of extent. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The closed-form solutions of simply supported cross-ply laminated composite and sandwich plates have been obtained. The results of present theory are compared with those of the classical plate theory (CPT), first order shear deformation theory (FSDT), higher order shear deformation theory (HSDT) of Reddy and exact three dimensional elasticity theory wherever applicable. The results predicted by present theory are in good agreement with those of higher order shear deformation theory and the elasticity theory.

• Journal of Welding and Joining
• /
• v.10 no.3
• /
• pp.54-62
• /
• 1992

Large steel water pipes are joined prevalently by bell and method and welded at inside and outside of lapped parts. According to the Korean Standard(KS) for fabrication of water pipes, the weldments are designed to have the length of leg which is same as or larger than the thickness of the pipe. It is recently pointed out that the standard size of weldments is too large, which results in an excessive consumption of material and labor. In this study, several cases of weldments having different sizes were investigated to reduce the length of leg to the effective size. For each case, the analysis of stresses was carried out to evaluate the safety of the welded pipes by using a package program, ANSYS, under the consideration of the loading condition of water pipes which includes the soil pressure on the pipe, the load over the road, and temperature change of the pipe. The results of this study revealed that the weldment which has the length of leg of the size over 0.7*thickness of the pipe could provide a stress level below the yield strength. Especially when the length of leg is 85% of the wall thickness, the maximum equivalent stress is only slightly higher than that of the leg of fillet of the size of 1.0*pipe thickness.