• 한국가스학회:학술대회논문집
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• 2005.05a
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• pp.220-220
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• 2005

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.211-213
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• 2002

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.469-470
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• 2005

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.198-202
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• 2015

We present a series of simple but novel nanopatterning methodologies inspired by traditional mechanical machining processes involving rolling, pullout, and forging. First, we introduce roll-to-roll nanopatterning, which adapts conventional rolling for continuous nanopatterning. Then, nano-inscribing and nano-channel lithography are demonstrated, whereby seamless nanogratings can be continuously pulled out, as in a pullout process. Finally, we discuss vibrational indentation micro- and nanopatterning. Similarly to the forging/indentation process, this technique employs high-frequency vertical vibration to indent periodic micro/nanogratings onto a horizontally fed substrate. We discuss the basic principles of each process, along with its advantages, disadvantages, and potential applications. Adopting mature and reliable traditional technologies for small-scale machining may allow continuous nanopatterning techniques to cope with scalable and low-cost nanomanufacturing in a more productive and trustworthy way.

• Macromolecular Research
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• v.17 no.8
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• pp.568-574
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• 2009

We investigated the sintering and consolidation phenomena of silver nanoparticles under various thermal treatment conditions when they were patterned by a contact printing technique on polyimide substrate films. The sintering of metastable silver nanoparticles commenced at 180 $^{\circ}C$, where the point necks were formed at the contact points of the nanoparticles to reduce the overall surface area and the overall surface energy. As the temperature was increased up to 250 $^{\circ}C$, silver atoms diffused from the grain boundaries at the intersections and continued to deposit on the interior surface of the pores, thereby filling up the remaining space. When the consolidation temperature exceeded 270 $^{\circ}C$, the capillary force between the spherical silver particles and polyimide flat surface induced the permanent deformation of the polyimide films, leaving crater-shaped indentation marks. The bonding force between the patterned silver metal and polyimide substrate was greatly increased by the heat treatment temperature and the mechanical interlocking by the metal particle indentation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1507-1510
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• 2005

This study was carried out as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-\mu{m}-deep$ indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.49 GPa and 100 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46-0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined area during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.439-445
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• 2011

Forensic Engineering is the art and science of professionals qualified to serve as engineering experts in courts of law or in arbitration proceedings. Buses using compressed natural gas (CNG) trend to be extended in use internationally as optimal counterplan for reducing discharge gas of light oil due to high concern about environment. However, CNG buses have to be equipped with composite pressure vessels (CPVs); since the CPVs contain compressed natural gas, the risks in the case of accident is very high. Hence, the investigation of such accidents is usually associated with engineering analysis. Among the possible reasons for such CNG explosion accidents is vehicle fire and vessel fracture. By conducting formal inspection and engineering tests, in this study, the cause of vessel explosion is investigated by analyzing the failure mechanism by fractography and by comparing the material properties of a reference part with those of a problem part by adopting instrumented indentation technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1663-1668
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• 2012

A spacer grid, which is one of the structural components in a PWR fuel, is an interconnected array of slotted grid straps that are welded at the intersections to form an egg-crate structure. The spacer grid is required to have sufficient lateral crush strength to enable nuclear reactor shut-down during abnormal operating environments. Previous studies on the lateral crush strength analysis of the spacer grid were performed using only the base material properties. In this study, to investigate the effect of the lateral crush strength of the spacer grid when using the mechanical properties in the weld zone instead of the base material properties, lateral crush strength analysis by considering the mechanical properties in the weld zone as obtained from the instrumented indentation technique was performed, and the results were compared with those of previous studies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1727-1732
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• 2010

Forensic engineering is the area of expertise of people qualified to serve as engineering experts in courts of law or during arbitration proceedings. An aerial-lifter can lift and carry load, including people, using power. Recently, failure of aerial-lifter internal parts while working and sweeping causing injuries and damage to property almost always generates conflict between the automaker and customer. Hence, the investigation of such events generally involves an engineering analysis. One of the possible reasons for accidents, such as a vehicle catching fire is the failure of oil pressure machine and the supporting pin. The results of formal inspections and engineering tests can reveal the cause for the failure of the mechanical parts. Therefore, the failure mechanism is analyzed by adopting fractography methods and by applying an instrumented indentation technique to compare the material properties of the reference part with those of the malfunctioning part.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.255-261
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• 2010

Forensic engineering is the area of expertise of those qualified to serve as engineering experts in courts of law or arbitration proceedings. Especially failure of internal parts during vehicle fire accidents causing injuries and damage to property almost always generates conflict between the automaker and customer. Hence, the investigation of such events generally involves an engineering analysis. One of the possible reasons for such accidents caused by vehicle fire is the failure of the piston and connecting rod. By formal inspections and engineering tests, this study shows the results of investigation and the cause of failure of the mechanical parts. For this purpose the failure mechanism is analyzed by using fractography methods and by applying an instrumented indentation technique to compare the material properties of the reference part with those of the malfunctioning part.