• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.49-52
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• 2005

Flutter analysis procedure can be divided into two steps such as the computation of generalized mass, stiffness, and unsteady aerodynamic matrices and the calculation of major vibration modes frequency and damping values at each flight speed by solving the complex eigenvalue problem. In aircraft flutter analyses, most of the time is spent in the process of computing the unsteady aerodynamic matrices at each Mach-reduced frequency pairs defined. In this study, the method has been presented for computation and extraction of unsteady aerodynamic matrix portions dependent only on aerodynamic model using DMAP ALTER in MSC/NASTRAN SOL 145. In addition, efficient flutter analysis method has been suggested by computing and utilizing the unsteady generalized aerodynamic matrices for each analysis condition using the unsteady aerodynamic matrix portions extracted above.

• Journal of Embryo Transfer
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• v.28 no.2
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• pp.133-139
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• 2013

The objective of this study was to determine the effect of post-activation treatment with cytoskeletal regulators in combination with or without 6-dimethylaminopurine (DMAP) on embryonic development of pig oocytes after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT). PA and SCNT oocytes were produced by using in vitro-matured pig oocytes and treated for 4 h after electric activation with $0.5{\mu}M$ latrunculin A (LA), $10.4{\mu}M$ cytochalasins B (CB), and $4.9{\mu}M$ cytochalasins D (CD) together with none or 2 mM DMAP. Post-activation treatment of PA oocytes with LA, CB, and CD did not alter embryo cleavage (85.8~88.6%), blastocyst formation (30.7~ 32.4%), and mean cell number of blastocysts (33.5~33.8 cells/blastocyst). When PA oocytes were treated with LA, CB, and CD in combination with DMAP, blastocyst formation was significantly (P<0.05) improved by CB+DMAP (42.5%) compared to LA+DMAP (28.0%) and CD+DMAP (25.1%), but no significant differences were found in embryo cleavage (77.5~78.0%) and mean blastocyst cell number (33.6~35.0 cells) among the three groups. In SCNT, blastocyst formation was significantly (P<0.05) increased by post-activation treatment with LA+DMAP (32.9%) and CD+DMAP (35.0%) compared to CB+DMAP (22.0%) while embryo cleavage (85.5~85.7%) and blastocyst cell number (41.1~43.8 cells) were not influenced. All three treatments (LA, CB, and CD with DMAP) effectively inhibited pseudo-polar body extrusion in SCNT oocytes. The proportions of oocytes showing single pronucleus formation were 89.6%, 83.9%, and 93.3%, respectively with the increased tendency (P<0.1) by LA+DMAP and CD+ DMAP compared to CB+DMAP. Our results demonstrate that post-activation treatment with LA or CD in combination with DMAP improves pre-implantation development of SCNT embryos and the stimulating effect of cytoskeletal modifiers on embryonic development is differentially shown depending on the origin (PA or SCNT) of embryos in pigs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.77-84
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• 2003

Structural analyses of a turbine bladed-disk for a liquid rocket turbopump are peformed to investigate the safety level of strength and vibration at design point. Due to the high rotational speed of the turbopump, effects of centrifugal forces are carefully considered in the structural analysis. Thermal load caused by extreme temperature distribution is also considered as an external force applied to turbine bladed-disk. A three dimensional finite element method (FEM) is used for cyclic symmetry structural analyses with the MSC/NASTRAN DMAP Alter. Interblade phase angles are considered to investigate structural dynamic characteristics as a function of rotational speed. Through the numerical analysis, effects of centrifugal and thermal loads on the turbine bladed-disk are examined.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.1-8
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• 2004

In this study, the method of computing and extracting the generalized unsteady aerodynamic matrices using MSC/NASTRAN and MSC/NASTRAN DMAP ALTER has been suggested for the analysis and control of aeroelastic phenomena such as flutter and gust response analysis. In addition to that, the method of approximating the generalized unsteady aerodynamic matrices using minimum state approximation method has been proposed in order to cast the aeroelastic equations of motion in state space form for aeroelastic analysis and control application. Simplified aircraft wing box model has been used for the validation of the methods suggested in this study.