• Proceedings of the Korean Society of Crop Science Conference
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• 2022.04a
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• pp.134-134
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• 2022

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.75-83
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• 2001

In this paper, numerical analysis is used to find the effects of inclination of rear end on flow characteristic around an automobile. The reference slant angle of rear end is 28.6$^{\circ}$, the slant angle of rear end is decreased to 24$^{\circ}$, 26.6$^{\circ}$ and also increased to 31.6$^{\circ}$, 36.4$^{\circ}$. The 3-D incompressible Navier-Stockes equations are solved by the iterative time marching scheme. The computed surface pressure coefficients were compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag, lift with respect to inclination angle of rear end are systematically studied. The flow characteristic on the automobile surface with respect to change of inclination of rear end have been also studied.

• Journal of computational fluids engineering
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• v.4 no.1
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• pp.53-61
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• 1999

Two-dimensional, unsteady, incompressible and compressible Navier-Stokes codes are developed for the computation of the viscous turbulent flow over high-lift airfoils. The compressible code involves a conventional upwind-differenced scheme for the convective terms and LU-SGS scheme for temporal integration. The incompressible code with pseudo-compressibility method also adopts the same schemes as the compressible code. Three two-equation turbulence models are evaluated by computing the flow over single and multi-element airfoils. The compressible and incompressible codes are validated by predicting the flow around the RAE 2822 transonic airfoil and the NACA 4412 airfoil, respectively. In addition, both the incompressible and compressible code are used to compute the flow over the NLR 7301 airfoil with flap to study the compressible effect near the high-loaded leading edge. The grid systems are efficiently generated using Chimera overlapping grid scheme. Overall, the κ-ω SST model shows closer agreement with experiment results, especially in the prediction of adverse pressure gradient region on the suction surfaces of high-lift airfoils.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.1-7
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• 2006

In the present study, A 3-D chimera technique for overlapped bodies in relative motion is studied using unstructured meshes. If all node points of a mesh element at solid boundary are in another body, this element is excluded from computational domain. For computation of unsteady flow, non-active cells have proper variables using interpolation and extrapolation. These variables are used in next time step. The motion of a launching trajectory ejected from a wing and the motion of deploying fins of a trajectory which have not been simulated are computed to conform practicality of this technique.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.1-10
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• 2002

Flow computations around forward sweep wing small aircraft have been conducted in this study. The main-wing of the forward-wing small aircraft is composed of two planforms: the inboard wing section with backward sweep angle which is known as strake and the outboard wing section with forward sweep angle. The geometrical discontinuity or kink generated by the combination of these two different planforms requires detailed flow analysis around wing. Four different solvers were used to calculate aerodynamic data and the accuracy of each method is examined. For the convenience of grid generation over the aircraft geometry, the overset grid method was applied. Through this calculation, the basic aerodynamic data of the forward-wing aircraft were provided and the aerodynamic characteristics of the wing is expounded.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.743-750
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• 1999

Human and bovine dopamine transporters (DAT) demonstrate discrete functional differences in the dopamine (DA) transport and cocaine binding. The functional analyses on the chimeras of human and bovine DAT have revealed that the region from the $133^{rd}{\;}to{\;}186^{th}$ residue(encompassing the $3^{rd}$ trans-membrane domain (TM) is responsible for the substrate transport and cocaine binding. The present studies have been done to find out the specific amino acid(s) which is essential for the binding of cocaine to DAT by interchanging the amino acids in that region between human and bovine DAT. When isoleucine, the $152^{nd}$ residue of chimera B3 (bovine DAT sequence) was transformed back to valine, the human DAT residue at the identical position, the cocaine binding was remarkably recovered to 98% of the human DAT values. In addition, the cocaine binding of the human DAT was decreased by 57% by substituting isoleucine for valine at position 152. When isoleucine at position 152 of the chimera B3 was converted to the other amino acids to provide an possible molecular basis for the functional role of the $152^{nd}$ residue, only the conversion to alanine among acids tested significantly the cocaine by 34%, but these effect were not as much as those by the conversion to valine. In conclusion, valine at position 152 is a crucial amino acid for the interaction of cocaine to the DAT.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.711-722
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• 2008

A projectile when passes through a moving shock wave, experiences drastic changes in the aerodynamic forces as it moves from a high-pressure region to a low pressure region. These sudden changes in the forces are attributed to the wave structures produced by the projectile-flow field interaction, and are responsible for destabilizing the trajectory of the projectile. These flow fields are usually encountered in the vicinity of the launch tube exit of a ballistic range facility, thrusters, retro-rocket firings, silo injections, missile firing ballistics, etc. In earlier works, projectile was assumed in a steady flow field when the computations start and the blast wave maintains a constant strength. However, in real situations, the projectile produces transient effects in the flow field which have a deterministic effect on the overtaking process. In the present work, the overtaking problem encountered in the near-field of muzzle guns is investigated for several projectile Mach numbers. Computations have been carried out using a chimera mesh scheme. The results show that, the unsteady wave structures are completely different from that of the steady flow field where the blast wave maintains a constant strength, and the supersonic and subsonic overtaking conditions cannot be distinguished by identifying the projectile bow shock wave only.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2001.11a
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• pp.71-73
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• 2001

In this study, we could improve transmission efficiency of germline chimeras by transfer of gonadal PGCs (gPGCs) cultured in vitro. Of hatched recipient chicks, 301 chickens (141 males and 160 females) were brought up to sexual maturity and these WLs (KOC) were mated with KOCs for testcross, resulting in 27 germline chimeras (15 males and 12 females) identified by black feather color of their progenies. The production efficiency of germline chimera production of experimental groups was observed (P=0.6831). The average transmission efficiency of proven germline chimeras was 0.6 ∼56.5% (15.0% on average). The transmission efficiency of experimental group which were transferred 10-days cultured gPGCs without Ficoll treatment was highest (49.7%) and that of experimental stock which transferred non-cultured gPGCs with Ficoll treatment was lowest (0.6%). The duration of in vitro culture before transferring was significantly important for the high efficiency of germline transmission. Transferring 10-days cultured gPGCs made the transmission efficiency higher rather than transferring non-cultured and 5-days cultured gPGCs, 50 times and 10 times, respectively (p<0.0001). However, Ficoll treatment for increasing the population ratio of gPGCs negatively affected the transmission efficiency and the effects of sexuality and the reciprocal interaction between treatments showed no significant differences. These findings demonstrated that the crucial factors for improving the germline transmission were the duration of in vitro culture prior to transfer. Thus, we developed the complete system for production of germline chimera using cultured gPGCs with highly improved efficiency and this system would be useful for genetic manipulation and obtaining the transgenic aves.

• Journal of Life Science
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• v.21 no.12
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• pp.1778-1783
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• 2011

Hematopoietic cytokines regulate production of blood cells by stimulating proliferation and differentiation of bone marrow cells. Among these hematopoietic cytokines, called hematopoitic growth factors, glranulocyte-colony stimulating Factor (G-CSF), which regulates growth of neutrophils, is one of important therapeutic factors because cancer patients suffer with neutropenia which is severe reduction of neutrophils after chemotherapy. Two groups of recombinant G-CSF have approved and used for therapeutic purposes and many researches are still on-going to produce recombinant G-CSF by different techniques. We engineered human G-CSF with Bombyx specific endoplasmic reticulum (ER) signal sequence, therefore, secretion of human G-CSF protein was improved in Bombyx mori-origined cell line, Bm5. The Bombyx ER signal sequence and human G-CSF matured protein region chimera was further remodeled at the N-terminus of matured G-CSF protein to understand roles of N-terminus on outer cellular secretion and/or production. Three different mutants were generated deleting three amino acids in non alpha-helical region in N-terminus in order to scan important amino acids for G-CSF secretion. One of 3 different N-terminal deletion mutants showed dramatically reduction of secreted amount of G-CSF indicating its important role on secretion. The data suggest that remodeling in non alpha-helical region of N-terminus is also important for recombinant G-CSF production.

• Journal of computational fluids engineering
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• v.9 no.1
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• pp.41-47
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• 2004

A successful store separation analysis tool, MSAP(Multi-body Separation Analysis Program) has been applied to F/A-18C/JDAM CFD Challenge Ⅱ. The challenge was devised to challenge CFD community to use CFD methodologies to predict and match the trajectory of a JDAM MK-84 separating from F/A-l8C. Trajectory simulations for two flight conditions were performed. Comparison between computed and measured flight trajectories for both conditions shows a good agreement.