• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.80-85
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• 2000

The hydroforming process is rapidly gaining popularity in the sheet metal forming industry. In this study, hydroforming process is applied to the seat back frame. The load-deformation characteristics of seat frame are simulated according to the test requirements by FMVSS. Structural analyses were performed with an analysis package program named I-DEAS for the conventional and the hydroforming seat back frame. The seat back frame made by hydroforming is not only about 23 percent lightweight, but also about 20 percent high strength compared with conventional that.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.64.1-64.1
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• 2012

Next generation displays such as high performance LCD, AMOLED, flexible display and transparent display require specific TFT back-planes. For high performance TFT back-planes, low temperature poly silicon (LTPS), and metal-oxide semiconductors are studied. Flexible TFT backplanes require low temperature processible organic semiconductors. Not only development of active semiconducting materials but also design and synthesis of semiconductor corresponding gate dielectric materials are important issues in those display back-planes. In this study, we investigate the high heat resistant polymeric gate dielectric materials for organic TFT and inorganic TFT with good insulating properties and processing chemical resistance. We also controlled and optimized surface energy and morphology of gate dielectric layers for direct printing process with solution processible organic and inorganic semiconductors.

• Proceedings of the KWS Conference
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• 1995.10a
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• pp.79-83
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• 1995

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

• 전자공학회논문지 IE
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• v.48 no.4
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• pp.7-12
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• 2011

This paper described a metal mount RFID tag that works reliably on metallic surface. The proposed method is to use commercial RFID tags, Styrofoam103.7 material is attached on back side of RFID tag. Styrofoam103.7 material which has 2.5 mm thickness and 1.03 relative permittivity, was attached on back side of RFID tag. In order to verify the performance of proposed method, we evaluated the experiment on the supply chain system of electric transformers using RFID. The experimental results on supply chain of electric transformers show that the proposed tags can communicate with readers from a distance of 2 m. The results of recognition rates are comparable to commercial metallic mountable tags.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.4
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• pp.1437-1448
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• 1996

This paper presents a simplified model for approximate analysis of the solute redistribution in coarsening dendrite arms during solidification of binary metal alloys. By introducing a quadratic concentration profile with a time-dependent coefficient, the integral equation for diffusion in the solid phase is reduced to a simple differential relation between the coefficient and the solid-liquid interface position. The solid fraction corresponding to the system temperature is readily determined from the relation, phase equilibrium and the overall solute balance in which the liquid phase is assumed to be completely mixed. In order to validate the developed model, calculations are performed for the directional solidification of Al-4.9 mass Cu alloy. The predicted eutectic fractions for a wide range of the cooling rate reasonably agree with data from the well-known experiment as well as sophisticated numerical analyses. Also, the results for the back diffusion limits are consistent with available references. Additional calculations show that the characteristic parameters such as the coarsening, density variation and nonlinarity in the phase diagram significantly affect the microsegregation. Owing to the simplicity, efficiency and compatibility, the present model may be suitable for the micro-macroscopic solidification model as a microscopic component.

• Design & Manufacturing
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• v.13 no.4
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• pp.17-22
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• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.104-109
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• 2011

The metal front case of a mobile phone is manufactured by press forming and welding of thin metal sheets. Twisting of the frame after the forming process is one of main obstacle for the assembly with reinforcement by welding. This study introduces a method preventing twisting of the metal front case frame in press forming. The spring-back after forming produces twisting of the frame, which leads to a low structural stiffness. To reduce twisting, connectors are required to reinforce the structural stiffness of the frame. In this study, the twisting profile is evaluated using a finite element(FE) analysis for various connector shapes. The actual connector shape is determined by minimization of the frame twisting within the tolerance of the FE-analysis. To verify the validity of the proposed blank shape, a forming experiment is performed and the twisting profile is measured using a 3D laser scanning method. The dimensional accuracy is found to be within the tolerance and in good agreement with the FE-analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4735-4741
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• 2010

The ultrasonic metal welding is highly used in extensive field due to the possibility for welding of various materials such as new materials, plated structures and etc, and its welding conditions has been diversify. In this paper, one-wavelength tool horn of step type designed for ultrasonic metal welding of dissimilar metal sheets has performed by FEM analysis. FEM analysis is applied to predict the natural frequency of ultrasonic tool horn and use of in the optimal design of ultrasonic horn shape. And the optimal design of one-wavelength step horn is confirmed experimentally using natural frequency analysis system.

• Design & Manufacturing
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• v.14 no.2
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• pp.49-55
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• 2020

Recently, when a new component of construction equipment is designed, a stamping process capable of producing parts having high appearance quality and precision has been gaining attention. However, in general, as it is developed based on existing parts made by welding metal sheets and tubes, frequent to die modification occurs, which increases the time and cost of developing new parts. Thus, it is necessary to reduce the cost by shortening the die development period. In this study, a stamping process was designed for the urea tank cover, which is a part for excavators, to reduce the die development period through sheet metal forming analysis. The stamping process was designed by determining the blank holding force after selecting the initial blank shape and size. The round value at the corner was modified such that formability is ensured. After selecting process parameters, the thickness reduction rate and spring-back effect were reviewed.