• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.527-528
• /
• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.93-94
• /
• 2012

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.02a
• /
• pp.325-326
• /
• 2009

• Proceedings of the Optical Society of Korea Conference
• /
• 2004.07a
• /
• pp.184-185
• /
• 2004

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.10a
• /
• pp.605-606
• /
• 2009

• Proceedings of the Optical Society of Korea Conference
• /
• 2004.02a
• /
• pp.114-115
• /
• 2004

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.9-10
• /
• 2010

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.2
• /
• pp.83-88
• /
• 2018

Additive manufacturing (AM) technologies have attracted wide attention as key technologies for the next industrial revolution. Among AM technologies using various materials, powder bed fusion (PBF) processes and direct energy deposition (DED) are representative of the metal 3-D printing process. Both of these processes have a common feature that the laser is used as a heat source to fabricate the 3-D shape through melting of the metal powder and solidification. However, the material properties of the deposited metals differ when produced by different process conditions and methods. 17-4 precipitation-hardening stainless steel (17-4PH SS) is widely used in the field of aircraft, chemical, and nuclear industries because of its good mechanical properties and excellent corrosion resistance. In this study, we investigated the differences in microstructure and mechanical properties of deposited 17-4PH SS by PBF and DED processes, including the heat treatment effect.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.21 no.1
• /
• pp.34-40
• /
• 2011

The bulk density, water absorption and microstructure of the artificial aggregates were controlled as a function of sintering temperature (1100 and $1200^{\circ}C$) and time (10~60 min) in the fabrication process of the artificial aggregates by the direct sintering process using dredged soil, the inorganic wastes. Also, the physical properties of the artificial aggregates fabricated according to the different sintering methods such as the direct sintering method used in this study and the increasing temperature sintering method used in the previous report, were compared and analysed. The bulk density of aggregates sintered at $1200^{\circ}C$ by the direct sintering method showed below 1.0, and the thickness of a shell and the pore size of the black core were increased with sintering temperature. Also, in the same sintering temperature, the area of black core was decreased, the thickness of shell was increased and the water absorption was decreased with sintering time. The black core of artificial aggregates of bulk density below 1.0 had the similar microstructure, regardless of sintering methods. In contrast, the shell of aggregates fabricated by the increasing temperature sintering method showed more dense microstructure than that by direct sintering method, hence the water absorption of aggregate sintered using direct sintering was relatively high. Thus, the direct sintering method is suitable for fabrication of artificial aggregates in ceramic carriers or absorbents applications.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.2 s.233
• /
• pp.228-231
• /
• 2005

In this paper, we present reusable quartz master fabricated by electron-beam lithography and dry etching process of quartz, and results of injection molding based on the reusable quartz master for the manufacturing of nano-scale information media. Since patterned structures of photoresist can be easily damaged by separation (demolding) process of nickel stamper and master, a master with photoresist cannot be reused in stamper fabrication process. In this work, we have made it possible of the repeated use of master by directly patterning on quart in nickel stamper fabrication process. We have designed and fabricated four different specimens including 100nm, 140nm 200nm and 400nm pit patterns. In addition, both intaglio and embossed carving patterns are fabricated for each specimen. In the preliminary test of injection molding, we have fabricated polycarbonate patterns with varying mold temperature. We have experimentally verified the fabrication process of the reusable quart master and possibility of quartz master as direct stamper.