• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.505-506
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• 2006

This study is focused on the manufacturing technique of powder injection molding of watch case made from zirconia powder. A series of computer simulation processes were applied to the prediction of the flow pattern in the inside of the mould and defects as weld-line. The material properties of melted feedstock, including the PVT graph and thermal viscosity flowage properties were measured to obtain the input data to be used in a computer simulation. Also, a molding experiment was conducted and the results of the experiment showed a good agreement with the simulation results for flow pattern and weld line location. On the other hand, gravity and inertia effects have an influence on the velocity of the melt front because of the high density of ceramic powder particles during powder injection molding in comparison with polymer's injection molding process. In the experiment, the position of the melt front was compared with the upper gate and lower gate positions. The gravity and inertia effect could be confirmed in the experimental results.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.881-882
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• 2006

In 1997, Dr. James Chien-Min Sung patented the technology of making diamond tools according to a predetermined pattern. The optimization of this pattern may double the tool life and the cutting speed. In 1998, Sung also made $DiaGrid^{(R)}$ saw segments that showed superior performance in cutting granite and marble. In 2000, Sung visited Shinhan and introduced them this revolutionary concept of diamond saw segments. In 2005, Shinhan adapted the idea and produced saw segments with diamond grits set in a predetermined pattern, their results confirmed that the sawing speed and the sawing life were both improved over conventional designs.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.33-39
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• 2004

Sandblasting has recently been developed into a powder blasting technique for brittle materials. In this study, the machinability of $Si_3N_4$-hBN based machinable ceramics are evaluated for micro - pattern making processes using powder blasting. Material properties of the developed machinable ceramics according to the variation of h-BN contents give a good machinability to the ceramics. The effect of scanning times, the size of patterns and variation of BN contents on the erosion depth of samples without mask and samples with different mask patterns in powder blasting of $Si_3N_4$-hBN ceramics are investigated. The Parameters are the impact angle of $90^{\circ}$, the scanning times of nozzle up to 40, and the stand-off distances of 100mm The widths of masked pattern are 0.1mm 0.5mm and 1mm. The powder used is Alumina particles, WA#600. and the blasting pressure of powder is 0.2MPa. Through required experiments, the results are investigated and analyzed. As the results, the machinability of the developed ceramics increases as the BN contents in the ceramics.

• Design & Manufacturing
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• v.11 no.3
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• pp.1-7
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• 2017

The fabrication process of micro pattern structure with high precision and high aspect ratio using powder injection molding (PIM) is developed. In the PIM process, the metal powder is mixed with the binder systems and the mixture is injected into the metal mold. The injection molded green parts are debinded and sintered to reach final shape and properties. In this method, the optimization of physical properties such as fluidity and strength of the binder system is essential for perfect filling the high aspect ratio micro-pattern. For this purpose, the correlation between the properties of the binder system and feedstock and ${\mu}-PIM$ process was investigated, and a binder system with low viscosity at low temperature(about $110^{\circ}C$) and high strength after cooling was investigated and applied. Employing this process, high precision parts with line type micro pattern structure which has pattern size $160{\mu}m$ and aspect ratio more than 2 can be manufactured.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.296-301
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• 2002

In this study, we investigated the machinability of machinable ceramics which were developed by a research lab. of Inha Univ., Korea. The effect of the nozzle scanning times, the size of patterns and compositions of BN in ceramics on the erosion depth of samples with no mask and samples with three different mask pattern in powder blasting of machinable ceramics. The blasting conditions were the impact angles 90$^{\circ}$, scanning times of noble up to 30 and the stand-off distances 100mm. The widths of mask pattern were 0.1mm, 0.5mm and 1 mm. The powder was alumina sharp particles, WA#600. The mass flow rate of powder during the erosion test was fixed constant at 150g/min and the blasting pressure of powder at 0.25Mpa

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.349-354
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• 2001

In this study, we investigated the effect of the impacting ang1e of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozz1e up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA#600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2MPa

• Composites Research
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• v.32 no.5
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• pp.237-242
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• 2019

In this research, a capacitive pressure sensor (Piezocapacitive Sensor) was fabricated using carbon black powder containing poly-dimethylsiloxane (PDMS) with micro-grid patterned surface. To investigate the effect of carbon black powder and micro-grid pattern on the sensor's performance, various sensors were fabricated with different carbon black powder concentration and grid pattern density. The performances of the developed sensors were compared in terms of operating range and sensitivity.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.686-691
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• 2006

Powder blasting technique was introduced to micromachine the micro patterns of circular and rectangular shape in LGP mould. The machinability of these patterns and matt treatment by powder blasting were verified. Then a prototype of LGP was injected by the developed LGP mould with micro patterns. Shape analysis of micro patterns and performance test of the injected LGP were carried out. The results showed printless LGP with micro patterns could be produced by just single injection using the mould with micro patterns, and powder blasting technique could be successfully applied to micrornachining of micro patterns and matt treatment of LGP mould.

• Journal of Ginseng Research
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• v.19 no.2
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• pp.138-143
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• 1995

Currently, some food materials are disinfected by $\gamma$-irradiation (using Co-60) or ethylene oxide treatment. These treatments were applied to ginseng powder and the ginseng components such as ginsenosides, polyacetylenes and phenolic acids were analyzed by HPLC to determine any compositional changes due to irradiation. No appreciable difference was observed in the HPLC pattern of ginsenosides, polyacetylenes of ginseng powder after 10 key irradiation or ethylene oxide treatment (EO $CO_2$= 3 : 7, w/wfb) from those of untreated fresh ginseng powder when they were analyzed soon after treatments. When the ginseng powders were stored at room temperature for three years after the same treatment, the HPLC patterns of polyacetylenes and phenolic acid fraction showed appreciable change from those of fresh ginseng powder, however, the HPLC patterns of three year old samples did not show any appreciable difference.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.28-34
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• 2004

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than 100${\mu}{\textrm}{m}$. In this study, we introduced oblique powder blasting, and investigated the effect of the impacting angle of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozzle up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA #600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2Mpa.