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Ultra-Precise Polishing of Mica Glass Ceramics Using MR Fluids and Nano Abrasives
백시영,송기혁,김기범,김병찬,강동성,홍광표,Beak, Si-Young,Song, Ki-Hyeok,Kim, Ki-Beom,Kim, Byung-Chan,Kang, Dong-Sung,Hong, Kwang-Pyo The Korean Society of Manufacturing Process Engine 2017 한국기계가공학회지 Vol.16 No.5
Mica-glass ceramics has features such as micro-sized crystals, high strength, chemical resistance, semitransparent optical properties, etc. Due to its superior material properties, mica glass ceramics have increasing applications in dental and medical components, insulation boards, chemical devices, etc. In many applications, especially for dental and medical components, ultra-precise polishing is required. However, it is known to be a very difficult-to-grind material because of its high hardness and brittle properties. Thus, in this study, a newly developed ultra-precise polishing method is applied to obtain nano-level surface roughness of the mica glass ceramics using magnetorheological (MR) fluids and nano abrasives. Nano-sized ceria particles were used for the polishing of the mica glass ceramics. A series of experiments were performed under various polishing conditions, and the results were analyzed. A very fine surface roughness of Ra=6.127 nm could be obtained.
Ultra-Precise Polishing of Mica Glass Ceramics Using MR Fluids and Nano Abrasives
Si-Young Beak(백시영),Ki-Hyeok Song(송기혁),Ki-Beom Kim(김기범),Byung-Chan Kim(김병찬),Dong-Sung Kang(강동성),Kwang-Pyo Hong(홍광표) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.5
Mica-glass ceramics has features such as micro-sized crystals, high strength, chemical resistance, semitransparent optical properties, etc. Due to its superior material properties, mica glass ceramics have increasing applications in dental and medical components, insulation boards, chemical devices, etc. In many applications, especially for dental and medical components, ultra-precise polishing is required. However, it is known to be a very difficult-to-grind material because of its high hardness and brittle properties. Thus, in this study, a newly developed ultra-precise polishing method is applied to obtain nano-level surface roughness of the mica glass ceramics using magnetorheological (MR) fluids and nano abrasives. Nano-sized ceria particles were used for the polishing of the mica glass ceramics. A series of experiments were performed under various polishing conditions, and the results were analyzed. A very fine surface roughness of Ra=6.127 nm could be obtained.
조은영 ( Eun Young Cho ),최창수 ( Chang Soo Choi ),유남진 ( Nam Jin Yoo ),황의태 ( Eui Tae Hwang ),이준영 ( Jun Young Lee ),강동백 ( Dong Beak Kang ),최석채 ( Suck Chei Choi ) 대한소화기학회 2009 대한소화기학회지 Vol.53 No.6
Paraduodenal hernias are rare congenital malrotational anomalies of midgut that arise in the potential spaces and folds of the posterior parietal peritoneum adjacent to the ligament of Treitz and can lead to intestinal obstruction. Also, they have shown several presentation patterns, such as asymptomatic, chronic intermittent abdominal pain, and acute severe abdominal pain. If symptomatic hernias with strangulation are untreated, according to the previous reports, they lead to overall mortality exceeding 50%. We report a case of the left paraduodenal hernia combined with small bowel obstruction from the patient who had no history of surgery before and developed abdominal pain after drinking of alcohol heavily. Abdominal CT scan showed sac-like mass of clustered in the left upper quadrant. The patient underwent the surgery of the bowel reduction and adhesiolysis and got uneventful recovery. (Korean J Gastroenterol 2009;53:369-372)