• Journal of Korean Society of Rural Planning
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• v.4 no.2
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• pp.58-69
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• 1998

This paper is to describe the characteristics of the Small Towns development in Rural China. The policies to develop Small Towns have been induced for solving the problem raised during the rural reform. The changes and adaptations of rural reform processes are integrated in Small Towns. The characteristics in the process of development of Ronggang, a small town, are as follows. First, it was the fund raised by rural inhabitants that was used for construction and development of the small town, Second, by implementing the policies of selective migration, the inhabitants of the small town have been differentiated from those of rural region. Third, the activities of commerce and industry of Ronggang have progressed to joint-stock system. Fourth, Having the spatial characteristics of self- development, the small town has grown and is expected to grow higher hierarchy of settlement system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.1-8
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• 1998

The explicit and implicit time integration methods are applied effectively to analyze sheet metal stamping processes, which include the forming stage and the springback stage consecutively. The explicit time integration method has better merits in the forming stage including highly complicated three-dimensional contact conditions. By contrary, the implicit time integration method is better for analyzing springback since the complicated contact conditions are removd and the computing time to get the final static state is short. In this work, brief descriptions of the formulation and the factor study for springback simulations are presented. Further, the simulated results for the S-rail and the roof pannel stamping processes are shown and discussed.

• Transactions of Materials Processing
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• v.14 no.6 s.78
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• pp.491-495
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• 2005

Micro injection molding analysis for microneedle fabrication was performed in the present study. The dimensions of width and thickness for in-plane microneedle are $600{\mu}m$, $500{\mu}m$, respectively. A delivery system based on guidelines for traditional injection molding was designed for four-cavities molding system. To investigate the effects of processing conditions in the mirconeedle fabrication, injection molding analysis using commercial code was performed. It was shown that the total injection time has a significant effect on the fabrication of in-plane microneedles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.55-59
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• 2005

Micro injection molding analysis for microneedle fabrication was performed in the present study. The dimensions of width and thickness for microneedle are 600um, 500um, respectively. A delivery system based on guidelines for traditional injection molding was designed for four-cavities molding system. To investigate the effects of processing conditions in the mirconeedle fabrication, injection molding analysis using commercial code was performed. It was shown that the total injection time has a significant effect on the fabrication of microneedles.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.389-392
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• 2005

In the modern days, a galvannealed sheet steel(GA) instead of a cold rolled steel sheet has been widely used as an alternative to extend the life of automotive body. Accordingly, the mechanical properties of GA for automobiles were taken Into account and studied by comparing with the temperature variation on annealing in this study. To clarify the effect of surface features in the mechanical properties of GA, the several tests such as nanoindentation and FE-analysis were executed. For this goal use is made of the method of neural networks. The developed neural networks apply also to obtain reliable mechanical properties of the thin films. Load-displacement curve was computed by the analysis procedure and compared with experimental results.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.614-622
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• 2004

A new approach for the automatic elimination of free edges in the finite element model for the analysis of sheet metal forming processes is presented. In general, the raw finite element model constructed from an automatic mesh generator is not well suited for the direct use in the downstream forming analysis due to the many free edges which requires tedious time consuming interactive graphic operations of the users. In the present study, a general method for the automatic elimination of free edges is proposed by introducing a CAD/CAE hybrid method. In the method a trimmed parametric surface is generated to fill the holes which are orginated from the free edges by using the one step elastic finite element analysis. In addition, mesh generation algorithm is suggested which can be used in the general trimmed surface. In order to verify the validity of the proposed method, various examples including actual automobile sheet metal parts are given and discussed.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.421-432
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• 2003

The dies & molds are a very economical production tool and a high value-added product because of its mass production capability compared to other production methods. Due to the very stiff international competitiveness, the industries meet many obstacles. For the promotion of the industry, the status and the international trends of the industry are measured. The vision and strategy are driven. In Korea, large portion of dies and molds are still low value-added and make large number of tools. In order to advance this industry to the high-tech area and gain competitiveness in the global marketplaces, effective means of resource investment and strategy should be properly provided.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.73-78
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• 2010

Recently, many researches on the development of super-hydrophobic surface have been concentrated on the fabrication of nano-patterned products. Nano-patterned mold is a key to replicate nano-patterned products by mass production process such as injection molding and UV molding. The present paper proposes the new fabricating method of nano-patterned mold at low cost. The nano-patterned mold was fabricated by electroforming the anodic aluminum oxide membrane filled with UV curable resin in nano-hole by capillary phenomenon. As a result, the final mold with nano-patterns which have the holes with the diameter of 100~200 nm was fabricated. Furthermore, the UV-molded products with clear nano- patterns which have the pillars with the diameter of 100~200nm were achieved.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.243-246
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• 2008

The press machine is actuated by the rotating motion of crank shaft and the reciprocating motion of slide. In recent years, unbalance moments and forces to the main frame attract many researches, as press technology becomes more miniaturized, precise, and rapid. In order to control vibrations caused by the rapid motions of the crank shaft and slide, this paper studies a resolution reducing the unbalance at the high speed knuckle press.

• Transactions of Materials Processing
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• v.30 no.2
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• pp.74-82
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• 2021

Stretch-flangeability, which is the ability of sheet steels to be deformed into complex shapes, is a critical formability property in automobile body parts. In this study, the center-hole for hole expansion test, which is normally used to evaluate the stretch-flangeability of sheet steels, was prepared by both punching and electrical discharge machining (EDM) methods. Hole expansion ratio (HER) of punched hole was far lower than the HER of EDM drilled hole because of damage/crack in hole-edge due to punching process. The effect of hole-edge condition on HER was quantified by mechanical, fractographic and geometric factors. Based on these factors, the empirical equation used to determine HER for various sheet steels was derived using non-linear regression.