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S. Jeong(정수환),M. Ko(고민성),S. M. Kim(김성민),H. Kim(김형건) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
Posterior leaflet prolapse of the mitral valve (MV) occurs with ruptured posterior chordae or enlarged posterior leaflet tissue. MV repair for posterior leaflet prolapse usually involves resection or neochordoplasty. An important surgical procedure in quadrangular resection, which requires a larger incision than triangular resection, is to determine the optimal incision size for the recovery of normal MV function. We created a virtual MV model containing chordal rupture and P2 leaflet prolapse, and virtually repaired the pathologic MV with quadrangular resection in terms of three different incision sizes using our previously-validated finite element-based MV simulation protocol. We compared the biomechanical and physiologic characteristics of the pre-repair MV and three different post-resection MVs. The normal MV revealed full leaflet coaptation at peak systole, whereas the P2 prolapse MV showed incomplete leaflet coaptation directly related to the occurrence of mitral regurgitation. Both post-resection MVs with a clinically appropriate incision size and with excessive tissue incision restored complete leaflet coaptation at peak systole. However, the post-resection MV with a small incision revealed incomplete leaflet coaptation. This virtual MV repair technique can provide a valuable pre-surgical evaluation tool to determine the optimal incision size for quadrangular resection to best recover normal MV function.
J. Y. Lee(이지연),H. C. Shim(심형철),S. M. Hyun(현승민),M. S. Oh(오민섭),S.-J. Jeon(전성재),S. H. Jeong(정수환) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
As the electric-vehicle market grows, the massive efforts have been tried to develop materials with high capacity and high power for lithium ion secondary batteries. Sn-based anode materials are highly promising due to high theoretical specific capacity (994 mAh/g) as well as high power density for its excellent electrical conductivity. However, the use of Sn has been limited by the delamination from the current collector and degradation in structural stability due to the large volumetric change of ~257% during lithiation and delithiation process. To solve this problem, many studies have been attempted to alleviate volume expansion by inserting Sn particles into a soft carbon matrix, but it has been considered difficult to mass-produce due to the complicated manufacturing process. In this work, graphene/Sn composite material was prepared by a laser processing followed by RF magnetron sputtering. Porous graphene structure was rapidly fabricated using a laser irradiation, and Sn layer was deposited on the graphene by sputtering. This simple and fast manufacturing techniques helps to produce graphene/Sn composites without complicated process, and can also be easily adaptable to mass production. The resulting graphene/Sn composite-based anode exhibited a high capacity of 430 mAh/g at 2C and stable cyclability over 700 cycles at