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MR polishing 적용을 위한 CI particle 크기에 따른 MR fluids의 유변학적 특성 분석
홍광표(K. P. Hong),이정원(J. W. Lee),하석재(S. J. Ha),조용규(Y. K. Cho),조명우(M. W. Cho),제태진(T. J. Je) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
MR (magnetorheological) fluids have been used to ultra-precision polishing optical glass and/or mold metal materials MR fluids were composed with CI particles (magnetic particle), DI water (carrier fluid), Na₂CO₃, Glycerin (stabilizer). In this study, the rheological properties of MR fluids which nano CI particles are dispersed were considered to compare the effects of micro sized CI particles, and MR polishing experiments were performed to evaluate the polishing properties of two types MR fluids. MR fluids based on two types of CI particle with different average size, 3.5㎛, 300㎚, were prepared. SEM, particle analyzer, and rheometer were utilized to investigate their rheological properties Sedimentations of MR fluids were measured to investigate the effects of dispersion stability. Finally, it was obtained the rheological properties (viscosity, shear stress, sedimentation) of MR fluid with larger particle size.
실리타 코팅된 CI particle을 이용한 SUS 304의 초정밀 연마
홍광표(K. P. Hong),이정원(J. W. Lee),하석재(S. J. Ha),조용규(Y. K. Cho),이현주(H. J. Lee),조명우(M. W. Cho),최형진(H. J. Choi),제태진(T.J.Je) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Recently, the magnetorheological (MR) polishing method has been performed as a new ultra precision polishing technique for many industrial applications. This method uses MR fluids, which consists of carbonyl iron (CI) particle, carrier fluid, additives and dispersion stabilizer. However, CI particle are easily oxidized in water. This problem leads to unpredictable polishing results and reduces the life of MR fluid. To solve the problem, in this study, Silica-coated CI particles were used for MR polishing. Their rheological properties were analyzed to compare silica coated MR fluid and uncoated MR fluid. As a result, in terms of surface roughness, MR polishing with silica-coated CI based MR fluid (Ra=1.89nm) shows a better than that of uncoated CI based MR fluid.
비구면 렌즈 형상정보 추출을 통한 렌즈 설계 및 성형해석에 관한 연구
송기혁(K. H. Song),홍광표(K. P. Hong),윤호섭(H. S. Yoon),이동원(D. W. Lee),조명우(M. W Cho) 한국소성가공학회 2015 금형가공 심포지엄 Vol.2015 No.8
The development of polishing technology has enabled the production of injection molding with high quality shaping. For products such as mobile phones which require high quality performances the use of plastic materials bring in many restraints such as shrinkage and deflection. The purpose of this research, therefore, is to use reverse engineering in order to find and analyze the data of a prechosen aspherical lens thereby creating a process to design an improved lens. Additionally, the improved lenses are subject to molding analysis. In order to solve this problem lens construction program, Zemax, is used to analyze and optimize performance. In the case of optimization, the object is to eliminate spherical aberration and to find good MTF data. The result of the optimization data was similar to the MTF data found through the random lens. Resin and analysis conditions were selected and CAD modeling was done to enhance the injection molding analysis.