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Jang, Jeong-Hwan;Joo, Byeong-Don;Lee, Jae-Ho;Moo, Young-Hoon
- Journal of the Korean Society for Heat Treatment
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- v.21 no.4
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- pp.183-188
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- 2008
Hot press forming allows geometrically complicated parts to be formed from sheet and the rapid cooling hardens them to extremely high strength. The main purpose of this research is to characterize Al coated layer in Al coated boron steel during hot press forming. For the hot press hardening experiment, test specimens were heated up to $810{\sim}930^{\circ}C$ and held for 3, 6 and 9 minutes, respectively. And then, some specimens were press hardened and others were air-cooled without any pressing for the comparison purpose. Al coated layer shows four distinct micro-structural regions of interest; diffusion zone, Al-Fe zone(I) low-Al zone(LAZ) and Al-Fe zone(II). Band-like LAZ is clearly shown at temperature ranges of $810{\sim}870^{\circ}C$ and sparsely dispersed at temperature higher than 900oC. The micro-cracking behavior in the Al coated layer during forming were also analyzed by bending and deep drawing tests. The strain concentration in softer LAZ is found to be closely related with micro-cracking and exfoliation in coated layer during forming.
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Jeon, Sang-Youl;Byun, Jae-Ho;Hahm, Ju-Hee;Hyoun, So-Young;Kim, Kwon-Hee
- Proceedings of the KSME Conference
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- 2000.11a
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- pp.712-717
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- 2000
Hydrostatic bearings have been applied to high precision machine tools and instruments, because the bearing has high stiffness, high damping and excellent straightness. This paper treats a procedure for designing a high precision press with linear hydrostatic bearings.
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Yoo, Nam-Hyun
- The Journal of the Korea institute of electronic communication sciences
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- v.13 no.6
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- pp.1243-1248
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- 2018
Metal Powder Metallurgy is a manufacturing technology that makes unique model parts or a certain type of product by using a hardening phenomenon when a powder of metal or metal oxide is put it into a mold and compression-molded by a press and then heated and sintered at a high temperature. Powder metallurgical press equipment is mainly used to make the parts of automobile, electronic parts and so on, and most of them are manufactured using precise servo motor. The intelligent precision servo control powder molding press system which is designed and implemented in this paper has advantages of lowering the price and maintaining the precision by using the mechanical camshaft for the upper ram part and precisely controlling the lower ram part using the high precision servo system. In addition, OPC-based monitoring and process data collection systems are designed and implemented to provide scalability that can be applied to smart manufacturing management systems that utilize Big Data in the future.
https://doi.org/10.13067/JKIECS.2018.13.6.1243 인용 PDF KSCI HTML

Kim, Min-Jae;Lee, Jun-Key;Hwang, Yeon;Kim, Hye-Jeong;Kim, Jeong-Ho
- Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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- 2009.06a
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- pp.290-290
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- 2009
Blu-ray Disk, the next generation optical information storing equipment used Blu-ray is the next generation leading storing equipment that has capacity is about from six times to thirty-five times bigger than the existing CDs, DVDs. Especially, we need elaborate optical pick-Up equipment to record and recognize detailed date. Moreover, Blu-ray disk has so narrow track-pitch so it is used high NA(Numerical Aperture) aspheric glass objective lens. In this research, we processed optical pick-up aspheric glass objective lens molding press core by parallel grinding method with ultra precision machining and mold core surface measured form accuracy(PV), surface roughness(Ra).
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