• Design & Manufacturing
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• v.6 no.1
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• pp.63-66
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• 2012

In the manufacturing of a LCD TV bottom chassis, the distortion after forming should be suppressed below pre-defined amount to avoid contact with electric components. Finite element analysis procedure of forming and springback of a LCD TV bottom chassis is developed to investigate the distortion behaviour. It is shown that after the first forming large distortion occur due to uneven metal flow induced by various embossings. In the second forming, distortion is decreased by introducing bead that absorbs the excessive metal flow. It is proved that analysis method could describe these behaviour effectively. The developed analysis method can be used to find the proper location and shape of bead more quickly and effectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.941-948
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• 2017

Recently, hydrogen energy has been in the spotlight as an alternative to diminishing fossil fuels and as a potential solution to environmental pollution. The development of hydrogen-fueled vehicles and the demands for improved fuel efficiencies have resulted in the need to increase the volume of the hydrogen pressure vessels. Pressure vessels having an elliptical bottom, as opposed to one that is hemispherical, allow for a greater capacity. However, there are insufficient studies on the feasibility of the forming process required for an elliptical bottom. In this study, the liner capacity is calculated according to the ratios of the major to the minor axes of the elliptical bottom part in a hydrogen pressure vessel. Structural safety is verified through finite element analyses, and the results are compared to the theoretical results. The feasibility of the proposed elliptical shape of the pressure vessel bottom, while filled to maximum capacity, is validated through forming analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.5
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• pp.223-230
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• 2007

Plasticity of clay bodies containing bottom ashes(BA) and small portion of other wastes was investigated. Plasticity indices of clay bodies using Atterberg limits were measured. It was confirmed that the plasticity indices could be applicable in actual forming process by extrusion. The forming possible compositions were found by changing the contents of water, bottom ash, stone dust, and sewage sludge. The relationship between the plasticity and physical properties of the aggregate green body was also investigated. The compositions for extrusion forming can be expected by measured the plasticity indices and these results were confirmed by real extrusion process. There is also strong relationship between the plasticity indices and the property of aggregate green body.

• Korean Journal of Metals and Materials
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• v.47 no.8
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• pp.494-499
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• 2009

As a novel method to produce a steel beam with 6mm thickness for buildings, a continuous roll forming process is reported. The roll shape is asymmetric and consists of 6 pairs of rollers to bend the steel plate from $0^{\circ}$ to $90^{\circ}$. Results obtained upon application of the roll forming process showed that the angle of the section plate is $90^{\circ}$. However, defects such as bowing and camber as high as 3.2 [$^{\circ}/m$] were observed. A FEM (Finite Element Method) analysis was applied to investigate the causes of the results for the region between rollers no. 5 and no. 6. The results of a FEM simulation of deformation and stress showed that there are some strong peak stresses on the upper surface and bottom surface of the material. The positions of the peak stresses did not show a correspondence between the upper and bottom surfaces. Thus, the defects in the process of roll forming with a 6 mm thick steel plate occur by the unbalanced stresses between the upper surface and bottom surface of the material in this study.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.90-96
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• 2016

Incremental sheet forming (ISF) is a highly versatile and flexible process for rapid manufacturing of complex sheet metal parts. Compared to conventional sheet forming processes, ISF is of a clear advantage in manufacturing small batch or customized parts. ISF needs die-less machine alone, while conventional sheet forming requires highly expensive facilities like dies, molds, and presses. This equipment takes long time to get preparation for manufacturing. However, ISF does not need the full facilities nor much cost and time. Because of the facts, ISF is continuously being used for small batch or prototyping manufacturing in current industries. However, spring-back induced in the process of incremental forming becomes a critical drawback on precision manufacturing. Since sheet metal, being a raw material for ISF, has property to resilience, spring-back would come in the case. It is the research objective to investigate how geometrical shaping parameters make effect on shape dimensional errors. In order to analyze the spring-back occurred in the process, this study experimented on Al 1015 material in the ISF. The statistical tool employed experimental design with factors. The table of orthogonal arrays of $L_8(2^7)$ are used to design the experiments and ANOVA method are employed to statistically analyze the collected data. The results of the analysis from this study shows that the type of shape and the slope of bottom are the significant, whereas the shape size, the shape height, and the side angle are not significant factors on dimensional errors. More error incurred on the pyramid than on the circular type in the experiments. The sloped bottom showed higher errors than the flat one.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.38-43
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• 2002

Die-less forming is a cold forming process which is to bend thick flat plates into compound curved plates using two asymmetric rollers. This forming method has several advantages compared with line heating which is widely used to fabricate compound curved pieces in shipyards. The die-less forming, however, has scarcely been studied. Even the deformation mechanism in this forming process has not been understood clearly. So, in this paper, the deformation characteristics of die-less forming is investigated analytically and numerically. for the analytic investigation, slab method based on equilibrium equation is applied. And the mechanism of curvature generation is derived for the asymmetry in roller applied. And three dimensional numerical analyses are performed with realistic modeling of interactions between the rollers and work-piece using finite element program, ABAQUS. It is shown that curvature generation is mainly due to the difference of normal positive strain distribution between the top and bottom surface of the work-piece. And a convex-type curved plate is formed if the center region of the work-piece is rolled with asymmetric rollers of which the lower is larger than the upper in diameter.

• Journal of Korea Foundry Society
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• v.22 no.5
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• pp.231-237
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• 2002

The structure and properties of HSLA steel obtained by Osprey forming process were investigated. The porosities were generated at the bottom of specimen due to the quenching effect of cold substrate during forming. The steel had a bainitic structure. The grain size were different among positions due to the cooling rates. The elements such as Mn, S, Si, Cr, Mo and etc. were contained in inclusions. They were formed at grain boundries. The size of them was $1{\sim}2{\mu}m$ and has nothing to do with the chemical composition. MnS and NbC were precipitated during rolling and aging.

• Transactions of Materials Processing
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• v.31 no.6
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• pp.384-393
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• 2022

The flow forming process consists of a split process, a divide process, and a forming process. The split process is a forming process in which rollers radially permeate a simple disc-shaped forging material and split it in both directions to form a top-bottom bidirectional cup. It is advantageous for post-processing to deepen the forming depth in the split process but this characteristic causes the failure near the edge of the mandrel during the actual process. The split process was analyzed using Rigid Plastic FEM, and the stress analysis of the mandrel was conducted to find the cause of the failure. It was found that the failure occurred due to fatigue accumulation damage caused by repeated residual stress.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.42-49
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• 2016

This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.182-183
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• 2019

In this study, the optimization of mixing proportion of press-forming board with blast furnace slag, pearlite and bottom ash was investigated using the response surface methodology. Ten Mixing proportions of specimens were designed by the response surface design, and then flexural failure load, moisture content and water absorption of specimens were measured. As a result of the reaction surface analysis based on the experimental results, it was possible to derive the optimal mixing proportion with the satisfaction of 93%.