• The Journal of Korean Institute of Information Technology
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• v.15 no.12
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• pp.165-171
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• 2017

This paper proposes a method of support-generation using morphological image processing instead of geometric calculations. The geometric computational cost is dependent on the shape, but our method is independent on the shape. For obtaining the external support area for extrusion shape, we represents morphological operations between two sliced layer images and shows results of each operation stages. Internal support area is evaluated from erosion and opening operations with the sliced-layer image. In these support areas, the supporter image is generated using the designed support structures. Also, we made a DLP printer and the STL model included supporter-structure is printed by the DLP printer. We confirmed the necessity of support-generation method with the support structures individually dependent on materials by looking at the printed results.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.11 s.188
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• pp.116-125
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• 2006

MEMS and LIGA technologies have been used for fabricating microstructures, but their shape is not 3D because of difficulty for preparation of many masks. To fabricate 3D microstructures, microstereolithography technology based on Digital Micromirror Device($DMD^{TM}$) was introduced. It has no need of masks and is capable of fabricating high aspect ratio microstructures. In this technology, STL file is the standard format as the same of conventional rapid prototyping system, and 3D parts are fabricated by layer-by-layer according to 2D section sliced from STL file. The UV light source is illuminated to DMD which makes bitmap images of 2D section, and they are transferred and focused on resin surface. In this paper, we addressed optical design of microstereolithography system in consideration of light path according to DMD operation and image-forming on the resin surface using optical design program. To verify the performance of implemented microstereolithography system, 3D microstructures with complexity and high aspect ratio were fabricated.

• Journal of the Korean Society of Food Culture
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• v.19 no.2
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• pp.129-138
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• 2004

The changes in DNA damage were investigated during storage after irradiation. Beef, pork and chicken were irradiated at 1.0, 3.0 and 5.0 kGy and stored for 6 months at $-20^{\circ}C$. The comet assay was applied to the sample muscles at the beginning of irradiation and at the end of storage. Muscles were isolated, sliced, and the suspended cells were embedded in an agarose layer. After lysis of the cells, they were electrophoresed for 2 min. and then stained. DNA fragmentation in tissues caused by irradiation was quantified as tail length and tail moment (tail length ${\times}$ % DNA in tail) by comet image analyzing system. Right after irradiation, the differences in tail length between unirradiated and irradiated muscles were significant(p<0.05) in beef, pork and chicken. With increasing the increasing doses, statistically significant longer extension of the DNA from the nucleus toward anode was observed. Similarly even 6 months after irradiation, all the irradiated muscles significantly showed longer tail length than the unirradiated controls. The results represented as tail moment showed similar tendency to those of tail length, but the latter parameter was more sensitive than the former. These results indicate that the comet assay could be one of the simple methods of detecting irradiated muscles. Moreover, this method suggest that using comet assay, we were able to detect DNA damage differences even after 6 months after irradiation.