• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.167-168
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• 2010

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.135-141
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• 2003

MEMS structures generally have been fabricated using surface-machining method, but the interface failure between silicon substrate and evaporated thin film frequently takes place due to the residual stress inducing by the applied the various loads. And the very important physical property in the heated environment is the linear coefficient of thermal expansion. Therefore this paper studied the residual stress caused the thermal loads in the thin film and introduced the simple method to measure the trend of the residual stress by the indentation. Specimens were made of materials such as Al, Au and Cu and thermal load was applied repeatedly. The residual stress was measured by nano-indentation using AFM and FEA. The existence of the residual stress due to thermal load was verified by the experimental results. The indentation length of the thermal loaded specimens increased minimum 11.8％ comparing with the virgin thin film caused by tensile residual stress. The finite element analysis results are similar to indentation test.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.1-6
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• 2010

Patterned optical components are widely used for optical products such as LCD and lighting. Since CCFL was used as a light source in the products, prism films having linear continuous optical patterns were widely used. However, LED which is a dot light source is popular recently, therefore, the optical products need new optical components having non-continuous optical patterns. Indentation machining method is a powerful method for machining of non-continuous pattern. When a copper mold and a brass mold were machined by this method, severe plastic deformation called pile-up was observed around the patterns. Since pile-up has negative relationship to ductility, this deformation can be eliminated by annealing treatment which makes the materials ductile. No plastic deformation occurred when machined after annealing at $600{^{\circ}C}$ and $575{^{\circ}C}$ for copper and brass, respectively. Finally, non-continuous optical patterns with high quality were machined on a copper mold and a brass mold successively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.1-6
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• 2018

Recently nano meter size pattern (sub-micro scale) can be machined mechanically using a diamond tool. Many studies have found a 'size effect' which referred to a specific cutting energy increase with the decrease in the uncut chip thickness at micro scale machining. A new analysis method was suggested in order to observe 'size effect' in nano scale machining and to verify the cause of the 'size effect' in this study. The diamond tool was indented to a vertical depth of 1,000nm depth in order to simplify the stress state and the normal force was measured continuously. The tip rounding was measured quantitatively by AFM. Based on the measurements and theoretical analysis, it was verified that the main cause of the 'size effect' in nano scale machining is geometrically necessary dislocations, one of the intrinsic material characteristics. st before tool failure.

• Journal of Powder Materials
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• v.4 no.3
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• pp.188-195
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• 1997

In most of sintered metal powder compacts, the sintered density distribution is controlled to be as high and uniform as possible to ensure the required mechanical properties. In general, the density distribution in the compacts is not uniform and not easy to measure. In the present study, a method for measuring the density distribution was developed, based on the indentation force equation by which the hardness and the relative density were related. The indentation force equation, expressed as a function of strength constant, workhardening coefficient and relative density, was obtained by finite element analysis of rigid-ball indentation on sintered powder metal compacts. The present method was verified by comparing the predicted density distribution in the sintered Fe-0.5%C-2%Cu compacts with that obtained by experiments, in which the density distribution was directly measured by machining the compacts from the outer surface progressively.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.163-170
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• 2004

Atomic force microscope (AFM) techniques are increasingly used fur tribological studies of engineering surfaces at scales ranging from atomic and molecular to micro-scale. Recently, AFM with suitable tips is being used for nano fabrication/nano machining purposes. In this paper, machining characteristics of silicon were investigated by nano indentation and nano scratch. Nano-scale material removal mechanisms are studied and the Taguchi method was introduced to acquire optimum parameters for nano machining. Also, Acoustic Emission (AR) is used for the monitoring of nano machining.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.50-55
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• 2003

Atomic force microscope(AFM) techniques are increasingly used for tribological studies of engineering surfaces at scales ranging from atomic and molecular to microscale. AFM with suitable tips is being used for nanofabrication nanomachining purposes. In this paper, machining characteristics of silicon have been investigated by nano indentation and nano scratch. Mechanisms of material removal on the microscale are studied and the Taguchi method is introduced to acquire optimum parameters for nanomachining. This work shows effectiveness of the Taguchi method in nanomachining. Also, Acoustic Emission(AE) is introduced for the monitoring of nanomachining.

• Design & Manufacturing
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• v.11 no.3
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• pp.46-50
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• 2017

Press processing is one of the best machining methods capable of mass production, satisfying dimensional, shape and quality among the methods of processing a metal plate. Among them, Fine blanking is a method of obtaining a precise cross-section such as machining of the shear surface shape. In this research, Using SCP-1 and SHP-1 materials. The deformation behaviors of the material flow affecting the die height of the shear section in accordance with the position of the V-ring in the Fine blanking were compared and analyzed. Result of interpretation, It was confirmed that the force acts on the position where the material flow direction accurately forms the die roll that the material of SCP-1 is at a position of 1.5 mm and the material of SHP-1 is at 2.0 mm. As a result, it was confirmed that the state of fo1111ing the shear surface by the V-ring was excellent. Using analysis results, In the experiment, the height of the die roll was considered by applying The position of the V-ring was 1.5 mm in SCP-1 and 2.0 mm in SHP-1. As a result of comparing the height of the die rolls, the height values of the die rolls were different from each other, It has been considered that the tendency of the die rolls to coincide with each other. It is considered that the difference of the die roll height is caused by the pressure input of the V-ring. In this study, the deformation behavior of the material(In addition to the position of the V-ring, the flow direction of the material depends on the shape of the V-ring and the Indentation amount) is considered to be an important factor in determining die roll height.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.19-27
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• 2016

Purpose: Laser treatment has become a popular method in implant dentistry, and lasers have been used for the decontamination of implant surfaces when treating peri-implantitis. This study was performed to evaluate the effects of an Erbium-doped:Yttrium-Aluminum-Garnet (Er:YAG) laser with different settings on machined (MA), sand-blasted and acid-etched (SA), and resorbable blast media (RBM) titanium surfaces using scanning electron microscopy and confocal microscopy. Materials and Methods: Four MA, four SA, and four RBM discs were either irradiated at 40 mJ/20 Hz, 90 mJ/20 Hz, or 40 mJ/25 Hz for 2 minutes. The specimens were evaluated with scanning electron microscopy and confocal microscopy. Result: The untreated MA surface demonstrated uniform roughness with circumferential machining marks, and depressions were observed after laser treatment. The untreated SA surface demonstrated a rough surface with sharp spikes and deep pits, and the laser produced noticeable changes on the SA titanium surfaces with melting and fusion. The untreated RBM surface demonstrated a rough surface with irregular indentation, and treatment with the laser produced changes on the RBM titanium surfaces. The Er:YAG laser produced significant changes on the roughness parameters, including arithmetic mean height of the surface (Sa) and maximum height of the surface (Sz), of the MA and SA surfaces. However, the Er:YAG laser did not produce notable changes on the roughness parameters, such as Sa and Sz, of the RBM surfaces. Conclusion: This study evaluated the effects of an Er:YAG laser on MA, SA, and RBM titanium discs using confocal microscopy and scanning electron microscopy. Treatment with the laser produced significant changes in the roughness of MA and SA surfaces, but the roughness parameters of the RBM discs were not significantly changed. Further research is needed to evaluate the efficiency of the Er:YAG laser in removing the contaminants, adhering bacteria, and the effects of treatment on cellular attachment, proliferation, and differentiation.