• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.97-100
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• 2003

Globally, the various machine components, as in electronics and communications, are demanded to being high-performance and micro-scale with abrupt development of the fields of computers, mobile communications. As this current tendency, production of the parts that must have high accuracy, so called milli-structure, are accomplished by the method of top-down, differently as in the techniques of MEMS, NANO. But, in the case of milli-structure, production procedure is highly costs, difficult and demands more accurate dimension than the conservative forming, processing technique. In this paper, forming analysis of the micro-former as the milli-structure are performed and then calculate the punch force etc. This information calculated is applied to decide the forming capacity of micro-former and design the process of forming stage, dimension of dies in another forming bodies. And, for the better precise forming analysis, elasto-plastic analysis is to be performed, then the consideration about effect of elastic recovery when punch and die are unloaded, have to be discussed in change of dimensions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.49-53
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• 2005

The objective of this research was to establish the size limitation of micro metal forming and analyze the formability of foil. Flat-rolled ultra thin metallic copper foil($3{\mu}m$ in thickness) was used as a forming material and foil was annealed to improve the formability at the temperature of $385^{\circ}C$. Forming die was fabricated by using etching technique of DRIE(deep reactive ion etching) and HNA isotropic etching. For the forming die and coupe. foil were vacuum packed and the forming was conducted as applying hydrostatic pressure of 250MPa to the vacuum packed unit. We successfully obtained the micro channels of $12\~14{\mu}m$ width and $9{\mu}m$ depth from micro forming process we designed. We also investigated the thickness strain distribution of foil from experiment and FE simulation result. Micro channels had a good formability of smooth surface and size accuracy. We expect that micro metal forming technology will be applied to production of micro parts.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.100-105
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• 2001

The manufacturing of metal bellows consists of the four main forming processes, deep-drawing, ironing, tube bulging and folding. Among these, the bulging and folding processes are critically important because the quality of metal bellows is greatly influenced by the forming conditions of these processes. In the present study, the finite element analysis technique is applied to the bulging and folding processes to obtain information about the design parameters of a metal bellows.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.141-145
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• 2000

A systematic method to find the optimal blank shape for sheet forming is proposed by coupling the numerical simulation technique. A weighted parameter was introduced in order to simplify the multi-variable optimization problem to a single-variable problem. The proposed method has been applied to the blank design of drawing processes to obtain the near-net shape within the required error bound after forming, Excellent results have been obtained between the numerical results and the target contour shapes. Through the investigation the proposed systematic method for optimal blank design is found to be effective in the practical forming processes

• International Journal of Quality Innovation
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• v.6 no.3
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• pp.204-215
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• 2005

This paper explores innovative manufacturing processes, which can be used to manufacture the national musical instrument of Trinidad and Tobago, the Musical Steel Drum or Steel Pan. The main manufacturing process used today is the manual hand-forming technique. In order to achieve more consistent and deeper formed components while maintaining the high quality of the instrument, it is proposed that the Marforming process and the Flow-forming process, an adaptation of the Spinforming process, be used more frequently in the future to replace the traditional Hand-forming method. In the traditional Spinforming technique material is pushed from the outer circumference of the metal disc to the center in progressive passes of the former. This results in a thinning of the outer region of the formed component with thickening of the center, however the opposite is required for the musical steel drum and by adapting the process the required strain distributions were achieved. Evaluation took the form of strain analyses of pre-formed steel drums and visual inspection of the quality of the surface finish. It was found that the Marformed components had the smallest range of strain values while the Spinformed components had the largest range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1338-1346
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• 2003

Three-dimensional formability of the thermoplastic laminar composite was studied according to manufacturing conditions. Five different types of the plain weave fabric were used as reinforcement with PET matrix. The square blank was made by press consolidation technique and formed in the type hemisphere. B-factor defined as the ratio of width of yarn and distance between yarns was used as the factor of formability in the type of plain weave fabric. The formability of PET/Glass fabric laminar composite was estimated in terms of forming rate and B-factor with the thickness distribution, area ratio of blank, and intra-ply shear angle. The thickness distribution across hemisphere was strongly affected by the B-factor, forming rate and blank thickness. The area ratio of blank was increased with B-factor, forming rate and blank thickness. Also, it was found that the intra-ply shear angle depends on the B-factor and forming rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.632-639
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• 2004

In this paper, an inverse problem of glass forming process is studied to determine a number of unknown heat transfer coefficients which are imposed as boundary conditions. An analysis program for transient heat conduction of axi-symmetric dimension is developed to simulate the forming and cooling process. The analysis is repeated until it attains periodic state, which requires at least 30 cycles of iteration. Measurements are made for the temperatures at several available time and positions of glass and moulds in operation. Heat removal by the cooling water from the plunger is also recorded. An optimization problem is formulated to determine heat transfer coefficients which minimize the difference between the measured data and analysis results. Significant time savings are achieved in finite difference based sensitivity computation during the optimization by employing distributed computing technique. The analysis results by the optimum heat transfer coefficients are found to agree well with the measured data.

• Journal of Institute of Convergence Technology
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• v.5 no.1
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• pp.7-12
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• 2015

Sheet metal formability can be defined as the ability of metal to deform without necking or fracture into desired shape. Every sheet metal can be deformed without failure only up to a certain limit, which is normally known as forming limit curve(FLC). In this paper, the dome stretching tests and tensile tests have been performed to obtain forming limit curve of aluminum alloy. During the experiment, failure strain is measured using digital image correlation(DIC) method. DIC method is a whole-field measurement technique that acquires surface displacements and strains from images information which characterized a random speckle as intensity grey levels. Recently years, this DIC method is being developed and used increasingly in various research. DIC results demonstrated the usefulness and ability to determine a strain.

• Journal of Korea Foundry Society
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• v.30 no.3
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• pp.94-99
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• 2010

When the returned scrap of bulk amorphous alloy is remelted, impurities such as oxides and intermetallic compounds increase. Glass forming ability of its scrap is deteriorated remarkably. Melt fluxing technique is introduced to enhance the glass forming ability during melting and freezing of bulk amorphous alloys. Cu and Zr based alloys are chosen. Small pieces of these alloy scraps and $B_2O_3$ flux are put together in a quartz tube. Cyclic heating and cooling are done by induction heating and water quenching or air cooling. Melting fluxing was effective for both Cu-based and Zr-based alloy, and their glass forming abilities were improved with increasing the number of fluxing.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1136-1141
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• 2003

Among various methods to manufacture the PDP barrier ribs, the pressing and the roll forming methods are simple and economical because they form the ribs by utilizing the plastic flow of the green tape in a relatively short time without generating air-polluting dusts. In the present study, the roll forming method was investigated by experiments as well as numerical analyses and in result the groove roll and the preform were designed. The effect of draft angle, comer radius, and initial thickness of the green tape on the plastic flow was examined by a series of parametric studies. The preform was recommended to ease the plastic flow into the grooves and to avoid the occurrence of crack during rolling and sintering processes.