• Structural Monitoring and Maintenance
• /
• v.3 no.3
• /
• pp.215-232
• /
• 2016

This paper presents a multi helical ultrasonic imaging approach for quantitative corrosion damage monitoring of cylindrical structures. The approach consists of two stages. First a multi helical ultrasonic imaging (MHUI) algorithm is used to provide qualitative images of the structure of interest. Then, an optimization problem is solved in order to obtain quantitative damage information, such as thickness map. Experimental tests are carried out on a steel pipe instrumented with six piezoelectric transducers to validate the proposed approach. Three thickness recesses are considered to simulate corrosion damage. The results show the efficiency of the proposed approach for quantifying corrosion location, area and remnant thickness.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.6
• /
• pp.647-652
• /
• 2015

Pull-in voltage model of nano-electro-mechanical system with graphene is investigated for the device optimization. In the pull in voltage model, thickness of graphene layer is assumed to be uniform in vertical and lateral direction. Finite element analysis simulation has verified the feasibility of the suggested model. From the suggested model, pull-in voltage change with graphene thickness and cantilever length can be estimated. Maximum induced stress and graphene thickness have a reciprocal relationship.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.5
• /
• pp.556-561
• /
• 2007

The rapid thermal response(RTR) molding is a novel process developed to raise the temperature of mold surface rapidly in the injection stage and then cool rapidly to the ejection temperature by air or water. The objectives of this paper are to investigate the effect of mold temperature, pressure and thickness of micro pattern molding and to provide a optimization of RTR injection molding for micro pattern from Moldflow simulation. Optimal minimum temperature and pressure was found without shortcut according to thickness. Filling percentage was influenced by glass transition temperature with the kinds of resin. Optimal temperature is slightly higher than glass transition temperature irrespectively of pressure, thickness, the kinds of resin in the micro pattern molding.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2011.09a
• /
• pp.95-100
• /
• 2011

In general, thickness of bottom floor in fore/aft cargo hold region for container ship has been determined based on FEM analysis result of mid cargo hold region. But this approach has room for improvement because section shape and frame spacing in fore/aft cargo hold of container ship are quietly different from those of mid cargo hold. From this study, correlation between FEM result and grillage analysis result has been investigated and simple method for thickness determination of bottom floor in fore/aft cargo hold using newly improved grillage analysis is proposed.

• Journal of Surface Science and Engineering
• /
• v.28 no.3
• /
• pp.164-173
• /
• 1995

Based on the potential-theory model for secondary current distribution, we could predict the thickness distributions of electroplating on patterned substrates with the different size of the auxiliary electrode. The substrates contain lithographic patterns at each sample geometry. Each sample geometry had different current distribution at the same condition except the size of the auxiliary electrodes. The size effect of the auxiliary electrode on thickness distribution of electrodeposition on patterned electrode was investigated in a series of experiments. Copper was galvanostatically deposited from an acid-sulfate solution in a reciprocating paddle cell. The thickness distributions of the workpiece scale measured by profilometry across the specimen were in good agreement with the current distribution predicted by boundary element method.

• Journal of Korean Society of Steel Construction
• /
• v.12 no.5 s.48
• /
• pp.515-525
• /
• 2000

The purpose of this paper was to develop size & shape optimization programming algorithm of plane trusses. The optimum techniques applied in this study were extended penalty method of Sequential Unconstrained Minimization Techniques(SUMT) and direct search method with multi-variables proposed by Hooke & Jeeves. Upper mentioned two methods were used iteratively at each level of size and shape optimization routines. The design variables of size optimization were circular steel tube(structural member) diameter and thickness, those of shape optimization were joint coordinates, and the objective function was represented as total weight of truss. During the optimum design, two level procedures of size and shape optimization were interacted iteratively until the final optimum values were attained. At the previous studies about shape optimization of truss, the member sectional areas and coordinates were applied as design variables. So that they could not apply the buckling effect of compression member. In this paper, actual sizes of member and nodal coordinates are used as design variables to consider the buckling effect of compression member properly.

• Steel and Composite Structures
• /
• v.34 no.3
• /
• pp.409-421
• /
• 2020

In the optimized structure sizing, the optimization methods are inserted in this context in order to obtain satisfactory solutions, which can provide more economical structures, besides allowing the consideration of the factors related to the environmental impacts in the structural design. This work proposes a mathematical model for the optimization of steel-concrete composite beams aiming to minimize the monetary cost and the environmental impact, using the Harmonic Search optimization method. Discrete variables were the dimensions of the steel profiles and the thickness of the collaborating slab of the composite steel-concrete beam. The proposed model was implemented in Fortran programming language and based on improvements in the structure of the optimization method proposed by Medeiros and Kripka (2017). To prove the effectiveness and applicability of the model, as well as the Harmonic Search method, analyzes were performed with different configurations of steel-concrete composite beams, in order to provide guidelines that make the use of these systems more streamlined. In general, the Harmonic Search optimization method has proved to be efficient in the search for the optimized solutions, as well as important considerations on the optimization of the monetary and environmental costs of steel-concrete composite beams were obtained from the developed examples.

• Transactions of Materials Processing
• /
• v.18 no.2
• /
• pp.177-182
• /
• 2009

A work of thin-walled outsell injection molding technology for a plastic part of moldframe applicable in a display product was performed in the present study. The thin-walled plastic part is one of the core parts in the display product, which supports and protects a light guide plate and back light unit from external environmental conditions. It globally has the shape of rectangular and surrounds the light guide plate and back light unit for each class of inch, however, the cross section of the part is not clear to define the thickness. This causes the difficult problem of injection molding itself for the part. Moreover, a metal outsell part makes a difficult problem in injection molding over it. Because the mold temperature control of the parts are not uniform in thickness direction due to the metal part. A careful injection melding analysis and injection mold design from the analysis results have to be proceeded to obtain a production of precision moldframe. Therefore, optimization for injection molding process and analysis of warpage characteristics were studied. Consequently, it was possible from the presented virtual manufacturing process that the manufacturing of precision thin-walled outsell moldframe.

• Tribology and Lubricants
• /
• v.23 no.3
• /
• pp.103-108
• /
• 2007

In this paper, the optimized design and strength analysis have been presented based on the finite element and Taguchi's experimental methods. The stress, strain and displacement characteristics of OPC drum tubes are affected by rolling contact pressures between an OPC drum tube and a paper, design parameters of an aluminum tube and material properties. The OPC drum tubes with nine different geometrical models are analyzed for design parameters that are related to the outer diameter, the thickness, and the length of an aluminum tube for a toner cartridge. The optimized design parameters for an aluminum tube may be selected as the outer diameter of 28 mm, the thickness of 0.8 mm, and the length of 220 mm. But the currently used aluminum tube for a laser printer is fairly optimized based on the Taguchi's design analysis. The calculated FEM results showed that the affection ratio of the design parameter t, which may control the strength of an aluminum tube, is the most influential parameter among the length and an outer diameter of a tube.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.7
• /
• pp.1232-1240
• /
• 2002

Recently, linear motors are applied to many small precision products. Thus high generating power with small size is required of it. In order to increase the motor efficiency, the design variables need to be optimized. In this study, Vector Fields FEM software, OPERA-3d, was used for simulating linear motor. The thrust and magnetic flux density at the air-gap center were simulated and compared with the experimental results. Taguchi method was applied to investigate the effects of each variables. As a result, the thickness of conductor and magnet was important for the thrust but the thickness of the yoke. The temperature of the conductor was determined by finding the thermal conductivity that was determined by experimentation. Correlation equation relating to the thrust and temperature was proposed by Latin square and Least Square method. The optimum design variables were determined by correlation equation, and compared with simulation results. According to this analysis, thrust force of linear motor was improved about 7% comparing with conventional model.