• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.73-83
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• 1992

Now composite resin restoration is clinically accepted in the repair of fractured PFM case, many mechanical surface treatment methods are performed to increase retentive force. The main purpose of this study was to compare the retentive force among the possible surface treatments and to insure the best method for the clinical application to the fractures porecelain and the exposed metal surface. To compare and to analyze the retentive force of repair resin, porcelain specimen were divided into 2 groups, etching group and non-etching group, and etching group were treated with 37% $H_3PO_4$, 1.23% APF, 10% HF and non-etching groups were treated with diamond bur, micro-sandblasasting. Also, metal specimens were divided by 2 groups : one was non-precious metal group which was treated with diamond bur, micro-sandblasting and tin plating and electrolytic etching, the other was precious metal group which was composed of micro-sandblasting treatment only and tin plating treatment with micro-sandblasting. Each specimen had been restored for 48 hours and the bond strength of each specimen was calculated with Universal testing machine. The results were as follows : 1. Porcelain specimen had higher bonding strength than metal specimen for the repair resin(P<0.01). 2. In porcelain specimen, 10% HF etching group had the highest bonding strength among etching and non-etching group. 3. Metal specimen treated with micro-sandblasting had highest bonding strength among the non-sandblasting had hightest bonding strength among the non-precious group, tin plating group had higher bonding strength than micro-sandblasting group between the precious metal groups. 4. Bonding strength of tin plating was increased in precious metal group only.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.163-168
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• 2006

In a micro-unit of electronic-machine, vibration can be excited by a small impact, and this vibration acts as a fatigue load. To measure the vibration effect on the micro unit, a micro dynamic tester is needed to test a micro specimen. In this paper, it has confirmed a movement of the PZT(piezo actuator) to use a sine signal. And, it has confirmed a fracture of specimens by using a tension-tension input signal in PZT. A metal-material property in the micro scale has been tested to compare with the macro scale. A fatigue test has been conducted by using PZT actuator to give a bending-tension effect.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.245-248
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• 2005

This paper is concerned with manufacturing technology of thin foil tensile specimen using CIP(Cold Isostatic Press) and measurement of precision mechanical property. This thin foil tensile specimen manufacturing technology is a method that can make a metal thin foil specimen for micro tensile testing. We can get a burr free micro metallic thin foil specimen using this technology. For testing mechanical property of this micro thin foil, we use a nano scale material testing machine that was developed by KITECH. In this paper, micro tensile specimens of nickel and copper thin foil are fabricated with CIP and precision mechanical properties of these materials could be measured. We will expect that precision mechanical property of micro/nano material and component. Micro and Nano mechanical property can be measured using this technology and mechanical property data base of micro/nano material and component can be constructed.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.117-127
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• 1991

The purpose of this study was to evaluate the effect of surface treatment of fractured metal-ceramic crown on bond strength of porcelain repair resin. The specimens were divided into two groups for metal specimens add five groups for porcelain specimens by surface treatment methods. the metal specimens were treated by 2 methods. : micro-sandblasting with $50{\mu}m$ aluminum oxide and grinding with diamond bur. The porcelain specimens were treated by 5 methods : micro-sandblasting with $50{\mu}m$ aluminum oxide, grinding with diamond bur, etching with porcelain etching agent, combination of micro-sandblasting and etching procedure, and combination of grinding and etching procedure. After surface treatment, each specimen was bonded with composite resin and the bond strength was measured and the surface texture was observed by scanning electromicroscope(SEM). The results were as follows : 1. There was significant difference in shear bond strength between metal specimen and prorcelain specimen. 2. Bood strength of metal specimens treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting. 3. Bond strength of porcelain specimen treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting and porcelain etching agent. 4. There was no significant difference in shear bond strength between the group treated with diamond bur and combined treatment groups respectively. 5. The large undercuts were observed in group treated with diamond bur by SEM.

• Transactions of Materials Processing
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• v.33 no.2
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• pp.118-122
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• 2024

Micro-electromechanical systems (MEMS) based in-situ heating holders have been developed to enable high resolution imaging of heat treatment analysis. However, unlike the standard 3 mm metal disk specimens used in the furnace-based heating holder and general transmission electron microscopy holder, the MEMS-based in-situ heating holder requires thin specimens that can be penetrated by electrons to be transferred onto the MEMS chip. Previously, focused ion beam milling was used to transfer metal specimens, but it has the disadvantage of being expensive and the risk of specimen damage due to gallium ions. Therefore, in this study, we devised a method of transferring metallic materials by ultrasonic treatment using a transmission electron microscopy specimen made by electro jet polishing. A 3mm electropolished metal disk was placed in an appropriate solution, ultrasonicated, and then drop casted. The transfer of the specimen was successful, but it was confirmed that dislocations were formed inside the specimen due to ultrasonic treatment. This study provides a novel method for transferring metallic materials onto MEMS chips, which is cost-effective and less gallium ion damaging to the specimen. The results of this study can be used to improve the efficiency of heat treatment analysis using MEMS-based in-situ heating holders.

• Analytical Science and Technology
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• v.19 no.5
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• pp.407-414
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• 2006

An X-ray diffractometer for spatially resolved X-ray diffraction measurements was developed to identify phase in the narrow (micron-scaled) region of high burn-up fuels and some nuclear materials. The micro-XRD was composed of an X-ray microbeam alignment system and a sample micro translation system instead of a normal slit and a fixed sample stage in a commercial XRD. The X-ray microbeam alignment system was fabricated with a microbeam concentrator having two Ni deposited mirrors, a vertical positioner, and a tilt table for the generation of a concentrated microbeam. The sample micro translation system was made with a sample holder and a horizontal translator, allowing movement of a specimen at $5{\mu}m$ steps. The angular intensity profile of the microbeam generated through a concentrator was symmetric and not distorted. The size of the microbeam was $4,000{\times}20{\mu}m$ and the spatial resolution of the beam was $47{\mu}m$ at the sample position. When the diffraction peaks were measured for a $UO_2$ pellet specimen by this system, the reproducibility ($2{\Theta}={\pm}0.01^{\circ}$) of the peaks was as good as a conventional X-ray diffractometer. For the cross section of oxidized titanium metal, not only $TiO_2$ in an outer layer but also TiO near an oxide-metal interface was observed.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.23-27
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• 2016

A 3D printed metal part and thermal plastic polymer part were joined by direct laser irradiation. The 3D metal part was fabricated by using DED(Direct Energy Deposition) with STS316 material. The experiment was carried out through no patterned metal surface, 3D metal printed surface and micro laser patterned surface. The most secure joining quality was obtained at the laser micro patterned surface specimen and the counterparts of polymers were PLA and PE based thermo plastics. The applied laser power was 350Watt and the distance of patterns was maintained at $150{\mu}m$. The laser line width was optimized at $450{\mu}m$ and the laser micro pattern depth was $180{\mu}m$ for the best joining quality. Based on the result analysis, the possibility of laser material joining for metal to polymer was proposed and multi-material joining will be possible in 3D laser direct material fabrication.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.773-774
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• 2006

Gas surface treatment is considered to be effective for titanium because of its high reactivity. In this study, we investigated the gas nitriding mechanism in titanium sintered parts produced by metal powder injection molding (MIM) process. The microstructure and nitrogen content of sintered MIM parts were greatly affected by nitriding conditions. Nitriding process strongly depended on the specimen size, for example, the size of micro metal injection molding (${\mu}-MIM$) product is so small and the specific surface is so large that the mechanical and functional properties can be modified by nitriding.

• Proceedings of the KWS Conference
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• 1993.05a
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• pp.132-134
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• 1993

The conventional way of molten nugget size measurement in welding process have utilized the metal-microscope by examining the micro sectioned weld specimen after micro-etching procedure. This paper proposes a new method for exact measurement of molten nugget size with the aid of the digital image processing unit and some developed software. This method proved to be convenient and precise in that resulting resolution and accuracy are as good as that of the conventional method.

• 한국항공운항학회:학술대회논문집
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• 2006.11a
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• pp.124-128
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• 2006