• Transactions of Materials Processing
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• v.31 no.2
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• pp.96-102
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• 2022

The multi-point dieless forming technology is one of flexible forming technologies that can form 3D curved surfaces of various shapes utilizing a lot of punch arrangements. A new technology that can simultaneously apply high-temperature forming and flexible forming technology by fusing local heating effect to such multi-point dieless forming technology was proposed in the present study. A simple local heating multi-point dieless forming apparatus was fabricated to confirm the applicability of this new technology. This equipment was designed to be used as a heat source by inserting heating cartridges in the head of the multi-point punch. Cartridges were used for all individual punches. Using the manufactured equipment, the time to raise the temperature to the target temperature and the surface temperature of the punch head part in contact with the plate were measured. In addition, forming experiments were carried out according to sheet material temperature (100 ℃, 200 ℃, and 300 ℃) to obtain forming results for each condition. The applicability and feasibility of this technology were confirmed through experimental results.

• Transactions of Materials Processing
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• v.18 no.8
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• pp.601-606
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• 2009

High strength steels are widely used for lightweight automobile parts and the control of springback is very important in sheet metal forming. The object of this study is to develop the forming process for stair type side sill made of high strength steel, DP780. Stair type side sill with local formed area and geometry change area can improve stiffness and design freedom but there are few studies for forming process. The forming technology considered in this paper is form type process, which has many advantages for forming of high strength steel compared with draw type process. Finite element analysis is carried out to predict formability and springback. It is shown that angle calibration of die is essential for reducing springback, and local forming involving bead is effective to control springback also. The effectiveness of local forming and angle calibration is verified by experimental.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.1
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• pp.17-23
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• 2009

The influence of different forming elements on the local paper structure and the related paper properties was investigated in this study. Specifically, a conventional papermaking foil system and a velocity induced drainage (VID) system were compared. The study involved the analysis of the product samples obtained from the commercial machine trials. The paper samples produced with VID forming systems showed better formation. The deterministic patter in the local structural profile map of the Foil samples indicated the structure of foil samples was more supple after forming process and then easier to be marked by various fabrics such as wet pressing fabric. The higher bulk was observed in the VID samples, which resulted in higher scattering coefficient, lower ZDT strength, and higher bending stiffness.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.60.2-60.2
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• 2014

Hierarchical structure of star-forming regions is widespread and may be characteristic of all star formation. We studied the hierarchical structure of star-forming regions in the Local Group galaxies (M31, M33, Phoenix, Pegasus, Sextans A, Sextans B, WLM). The star-forming regions were selected from Galaxy Evolution Explorer (GALEX) far-UV imaging in various detection thresholds for investigating hierarchical structure. We examined the spatial distribution of the hot massive stars within star-forming regions from Hubble Space Telescope (HST) multi-band photometry. Small compact groups arranged within large complexes. The cumulative mass distribution follows a power law. The results allow us to understand the hierarchical structure of star formation and recent evolution of the Local Group galaxies.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.301-306
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• 2009

High strength steels are widely used for lightweight automobile parts and the control of springback is very important in sheet metal forming. The object of this study is to develop the forming process for stair type side sill made of high strength steel, DP780. Stair type side sill with local formed area and geometry change area can improve stiffness and design freedom but there are a few studies for forming process. The forming technology considered in this paper is form type process, which have many advantages for farming of high strength steel compared with draw type process. Finite element analysis is carried out to predict formability and springback. It is shown that angle calibration of die is essential for reducing springback, and local forming involving bead is effective to control springback also. The effectiveness of local forming and angle calibration is verified by experimental.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.349-353
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• 2008

A fundamental study on warm incremental forming of a magnesium alloy sheet has been carried out. In order to enhance the incremental formability of the magnesium alloy sheet, a local heating device was newly designed and manufactured. Through the incremental forming tests of AZ31 under various forming conditions, the effects of process parameters such as the temperature, feeding depth per cycle, and inclination angle on the incremental formability of AZ31 were investigated. In addition, conventional FLDs at elevated temperatures were constructed experimentally and applied to predict the forming failure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.883-884
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• 2011

• Transactions of Materials Processing
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• v.32 no.6
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• pp.360-366
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• 2023

This study is concerned with the surface quality of products according to the material and coating condition of the forming tool in incremental sheet forming. Three forming tools, SKD11 with and without diamond-like-coating (DLC) and polymer tool tip, were used to form conical and pyramidal geometries to take into account the influence of friction between the forming tool and the sheet on the surface quality including geometric accuracy of deformed samples. Each test was performed using SUS304 with a thickness of 0.4 mm according to different incremental depths per lap of 0.5 mm, 1.0 mm, and 1.5 mm for the contour tool path, considering the increase in normal force which is associated with the frictional behavior during local deformation. The surface quality was then investigated through surface roughness measured with KEYENCE VR-6000 and relative strain distribution including deformed shape analyzed with ARGUS which is a non-contact optical strain measurement system. Differences between 3D CAD surfaces and captured geometry from experiments were evaluated to compare the effect of friction on geometric accuracy. From comparisons of experimental results, it was revealed that the polymer-based tool tip can improve surface quality and geometric accuracy by reducing the undesired material flow due to local friction in the increment sheet forming process.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.212-219
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• 2002

The pipe with a long-neck flange is widely used in power plants, chemical plants, and shipbuilding companies. Now the pipe with a long-neck flange is manufactured by welding a thick flange to a pipe. But this long-neck flange pipe has some defects in the welding region such as unfitting and local thermal fatigue, which weaken the strength around the neck of the flange. Moreover, after welding the flange, the contacting surfaces of the flange have to be machined flat. So, that is uneconomical. Therefore, to solve the above problems of the long-neck flange pipe, a new process, which has no defects around the flange neck, is required. In this study, three forming processes are suggested to get an enhanced long-neck flange. First suggested process consists of conical forming and flange forming. Second and third suggested processes consist of the bulging of a long pipe locally heated by induction coils and the flange forming. The differences between second and third suggestions are the thickness and local heating area of the pipe. That is, the thickness of the initial pipe of third suggestion is larger than that of the final product, and the local heating area is smaller than that of second suggestion. These three suggestions for forming a long-neck flange are simulated by FE analyses with a commercial code DEFORM 2D. Especially, the theoretical result of FE analysis on the first suggestion for forming a long-neck flange is verified by the experiment with aluminum 6063 pipes. From the theoretical and experimental results, it is concluded that three suggested processes are very useful in order to manufacture the pipe with a long-neck flange without any defects.

• Korean Journal of Oriental Medicine
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• v.4 no.1 s.4
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• pp.47-62
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• 1998

We explicate the forming mechanism of Sasang constitution as the principle of energy distribution which is based on the evolutionary hypothesis. The result was obtained as follows: 1. The principle of form-image (形象) in oriental medicine can be explained with the relation between structure and function that a life acquires through the adaptation and evolution. 2. The Sung-jung (性情) in Sasang constitutional medicine can be explained as the strategy for survival or the pattern of adaptation by which an individual or a species lives in this world. 3. The forming mechanism of Sasang constitutional organic phase (臟局) can be explained as the principle of energy distribution which includes three hypothesis (hypothesis of limited resources, hypothesis of preference and hypothesis of effectiveness). 4. It is postulated that the local hemodynamics is one of the most important factors that determine the difference of Sasang constitutional organic function. 5. The relation of metabolic rate, local hemodynamics and thermo-metabolism is inseparable and it is the important point of forming mechanism of Sasang constitution and the diagnosis of pulse.