• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.38-44
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• 2000

The background of this study lies in he investigation of the formation mechanism of ductile mode(nkanometer-size) chips of brittle materials such as fine ceramics glass and silicon. As the first step to achieve this purpose this paper intends to observe the micro-deformation behavior of these materials in sub${\mu}{\textrm}{m}$ depth indentation tests using a diamond indentor. In this study it was developed Ultra-Micro Indentation. Device using the PZT actuator. Experimentally by using the Ultra-Micro Indentation device the micro fracture behavior of the silicon wafer was investigated. It was possible that ductile-brittle transition point in ultimate surface of brittle material can be detected by adding an acoustic emission sensor system to the Ultra-Micro Indentation appartus.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.51-55
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• 1999

Recently, manufacturing work has been transformed to advanced technology intensive form from mass production with a little items required in the past. It was demanded that superior workpiece surface integrity. However, the study of ductile mode machining was proceeded actively.In this paper, it is developed Ultra-Micro Indentation Device using the PZT actuator. Experimentally, by using theUltra-Micro Indentation device, the micro fracture behavior of the silicon wafer was invesgated. It was possible that ductile-brittle transition point in ultimate surface of brittle material can be detected by adding an acoustic emission sensor system to the Ultra-Micro Indentation apparatus.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1139-1143
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• 2007

A simple method for the fabrication of 3D micro-nano hybrid patterns was presented. In conventional fabrication methods of the micro-nano hybrid patterns, micro-patterns were firstly fabricated and then nano-patterns were formatted on the micro-patterns. Moreover, these micro-nano hybrid patterns could be fabricated on the flat substrate. In this paper, we suggested the fabrication method of 3D micro-nano hybrid patterns using micro-indentation on the anodized aluminum substrate. Since diameter of the hemispherical nano-pattern can be controlled by electrolyte and applied voltage in the anodizing process, we can easily fabricated nano-patterns of diameter of loom to 300nm. Nano-patterns were firstly formatted on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns of diameter of 150nm were fabricated by anodizing process, and then micro-pyramid patterns of the side-length of $50{\mu}m$ were formatted on the nano-patterns using micro-indentation. Finally we successfully replicated 3D micro-nano hybrid patterns by hot-embossing process. 3D micro-nano hybrid patterns can be applied to nano-photonic device and nano-biochip application.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.5-13
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• 1995

Various techniques to measure fracture toughness which is an important parameter to predict fracture behavious of structural materials have been reported. Among these mathods, this paper describes the micro-Vickers indentation crack method to estimate the fracture toughness of some WC-Co composites. Two indentation crack patterns (such as radial-median cracks (orhalf-penny cracks) and Palmqvist cracks generated during indentation) are referred precisely. The fracture toughness of WC-4.7wt%Co, WC-6wr%Co and WE-9wr%Co composites were estimated by using some equations given by Shetty et al., Nihara et al. in this study. We show the reliability of indentation method by comparing the results with those from literatures. The appropriate equation to estimate the fracture toughness in the case of WC-Co composite is given. In addition, some technical informations in terms of the crack length by indentation in estimating the existence of the surface residual stress that prevents to obtain an accurate fracture toughness are presented.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.63-68
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• 2015

Micro/nano patterns for optical concentration and diffusion have been studied in the various fields such as displays, optics, and sensors. Conventional micro patterns were continuous and linear shapes due to using linear-type light sources, however, recently non-continuous patterns have been applied as point sources are used for dot-type light sources such as LEDs and OLEDs. In this study, a hybrid machining technology combining an indentation machining method and an AAO process was developed for manufacturing the non-continuous micro patterns having nano patterns. First, mirror-like surfaces ($R_a<20nm$) of pure Aluminum substrates were obtained by optimizing cutting conditions. Then, The letter of 'K' consisting of the arrays of the micro patterns was manufactured by the indentation machining method which has a similar principle to indentation hardness testing. Finally, nano patterns were machined by AAO process on the micro patterns. Conclusively, a specific letter having nano-micro hybrid patterns was manufactured in this study.

• Tribology and Lubricants
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• v.25 no.3
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• pp.163-170
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• 2009

We developed a compact micro indentation testing device (designated SNUT) which is capable to measure Young's modulus of a sample using depth and applied load data during indentation. Performance of this device was evaluated using pure Ti, pure Ni, and die steel (SKD11). As a result of analysing the indentation test data, the frame compliance $C_f$ was found to influence mainly the modulus by 80% among several factors affecting accuracy of Young's modulus. Project area, which was determined by indirect indentation method, was modified using direct SEM observation. Finally, Young's modulus error was reduced to 5% after taking into consideration the frame compliance and modified projected area from 80% error without any these two correction factors. The performance of SNUT and MTS instruments was compared using same specimen (pure Ti).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.405-406
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• 2006

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.385-392
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• 2016

Recently in the display industry, demands for high-luminance and resolution of display devices have been steadily increasing. Generally, micro linear patterns are applied to an optical film in order to improve its properties of light. However, these patterns are easily viewed to eyes and moire phenomenon can be occurred. Micro random patterns are proposed as a method to solve these problems, increasing light-luminance and light-diffusion. However, conventional pattern manufacturing technologies have long processing times and high costs making it difficult to apply to large area molds. In order to combat this issue, micro-random patterns are formed by using a roll to plate indentation method along with abrasive paper tools composed of AlSiO2, SiC, and diamond grains. Also, forming properties, such as size and fill-factor of random patterns, are analyzed depending on type, mesh of abrasive paper tools, and indentation forces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.227-228
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.743-744
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• 2007