• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.85-94
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• 1999

Transient aerodynamic response of an airfoil to a moving plane-flap is numerically investigated using two-dimensional Euler equations with conservative Chimera grid method. A body moving relative to a stationary grid is treated by an overset grid bounded by a 'dynamic domain-dividing line' the concept of which is developed in this study. A conservative Chimera grid method with a dynamic domain-dividing line technique is applied and validated by solving the flowfield around circular cylinder moving supersonic speed. The unsteady and transient characteristics of the flow solver is also examined by computations of a oscillating airfoil and a ramp pitching airfoil respectively. The transient aerodynamic behavior of an airfoil with a moving plane-flap is analyzed for various flow conditions such as deflecting rate of flap and free stream Mach number.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.99-109
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• 1998

This paper describes the analysis of flow and aeroacoustic field around a car-like body. The governing equations, 3-D unsteady incompressible Navier-Stokes equations, are solved with the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror, After the flow field analysis has been converged, the aerodynamic noise analysis of the side-view mirror has been performed by solving Ffowcs Williams and Hawkings equation. From the present numerical simulation, the A- and C-pillar vortex are evidently shown and the aerodynamic noise level induced by the side-view mirror is predicted to about 100dB.

• Korean Journal of Veterinary Research
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• v.30 no.2
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• pp.231-241
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• 1990

The present study was carried out to investigate the viability of frozen-thawed aggregated mouse embryos and to produce the chimeras. Different phenotypic embryos were obtained by mating ICR female mice with ICR or CBA male mice. The aggregated morulae were produced following aggregation of embryos at 4-, 8- and 12- to 16-cell stage. The desirable stage for the aggregation of the mouse embryos was 8- to 16-cell stage. The post-thawed in vitro survival rates of aggregated embryos in glycerol, DMSO and ethylene glycerol were 51.5, 78.6 and 69.4%, respectively. Although the higher survival was obtained in DMSO, there were no significant differences in the survival rates among the three cryoprotectants. A total of 155 frozen-thawed aggregated embryos were transferred to 11 recipient mice, 3 out of 7 offsprings were born to overt chimera. These experiments have proven that mouse chimeras can be obtained from frozen-thawed aggregated embryos.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1013-1018
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• 2010

This paper presents a numerical evaluation of the launch dynamics and thermo-fluid phenomena for gas generator launch eject system. The existing gas dynamic model for launching eject body used ideal gas and adiabatic assumption with empirical energy loss model. In present study, a turbulent Navier-Stokes solver with CHIMERA mesh is employed to predict the detail unsteady thermo-fluid dynamics for the launched body. The calculation results show that proper grid number is necessary for good agreement with experimental data. The important effects for accurate prediction are a gap distance and thermal boundary condition on the wall. The computational results show good agreement with experiment data.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1188-1195
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• 2001

A tetraparental chimeric bull was successfully produced by aggregating bovine IVF embryos of F1 (female Holstein${\times}$male Japanese Black) and F1(female Japanese Brown${\times}$male Limousin) and culturing in vitro without the zona pellucida at Yamaguchi Research Station in Japan. In the microsatellite genotyping, 12% (28/228) microsatellite primer sets ware potentially useful for this parentage analysis in the chimeric bull, 78.6% (22/28) of microsatellite present in the chimeric bull were uniquely contributed from the Japanese Black and 21.4% (6/28) from Limousin. This chimeric bull semen was used in producing IVF embryos. The chromosome preparations were made from peripheral lymphocytes. Based on chromosome analysis the Chimera had apparently normal chromosomes (29 acrocentric pairs, one large sub metacentric X chromosome and one small sub metacentric Y chromosome). The proportion of acrosome reacted spermatozoa after 1 h of incubation was higher (p<0.01) with the Chimera than with the Holstein and in Japanese Brown bulls. But did not differ from Japanese Black and Limousin bull sperm. Fertilization rates observed after 5 h of sperm-oocyte incubation with Chimera sperm were higher (p<0.05) than with Japanese Brown and (p<0.01) than with Holstein sperm, but did not differ from Japanese Black and Limousin sperm. The cleavage rates of IVF oocytes inseminated with Chimera sperm were also higher (p<0.001) compared with Holstein, (p<0.01) Japanese Brown and (p<0.05) Limousin, but did not differ from Japanese Black sperm. The blastocyst rates of IVM oocytes inseminated with sperm were higher (p<0.05) than in Limousin, Japanese Brown and Holstein, but did not differ from Japanese Black. Chimeric cattles were produced by aggregation of parthenogenetic (Japanese Brown) and in vitro fertilized (Holstein) bovine embryos at the Yamaguchi Research Station in Japan and by aggregation of parthenogenetic (Red Angus) and in vitro fertilized (Holstein) embryos at the St. Gabriel Research Station in Louisiana. The aggregation rate of the reconstructed demi-embryos cultured in vitro without agar embedding was significantly lower than with agar embedding. The aggregation was also lower when the aggregation resulted from a whole parthenogenetic and IVF-derieved embryos cultured without agar than when cultured with agar. The development rate to blastocysts, however, was not different among the treatment. To verify parthenogenetic and the cells derieved from the male IVF embryos in blastocyst formation, 51 embryos were karyotyped, resulting in 27 embryos having both XX and XY chromosome plates in the same sample, 14 embryos with XY and 10 embryos with XX. The viability and the percentage of zonafree chimeric embryos at 24 h following cryopreservation in EG plus T with 10% PVP were significantly greater than those cryopreserved without PVP. Pregnancies were diagnosed in both stations after the transfer of chimeric blastocysts. Twin male and single chimeric calves were delivered at the Yamaguchi station, with each having both XX and XY chromosomes detected. Three pregnancies resulted from the transfer of 40 chimeric embryos at the Louisiana station. Two pregnancies were Jost prior to 4 months and one phenotypically chimeric viable male born.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.387-390
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• 2006

Numerical study has been conducted in two dimensions about a NACA0012 airfoil with an oscillating microflap on the surface. We show that this microflap is effective in controlling the unsteady stall at high angles of attack. We solve the compressible Navier-Stokes equations for the Reynolds numbers with an extensible chimera grid fitted to the oscillatory microflap. For turbulent calculation, we adopt the SST $k-{\omega}$ model. We investigate the parametric effect of angle of attacks, Reynolds number, and the location where the microflap is installed.

• Journal of Embryo Transfer
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• v.9 no.3
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• pp.243-247
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• 1994

최근 의약적으로 유용한 단백질을 대량 생산키 위한 실현 가능한 방법이 유전자변환 가축의 이용과 관련되어 발전되어 왔다. 이러한 유전자 변환동물은 이종의 단백질을 유즙속으로 분비시키는 생체반응기로서 이용되고 있다. 이러한 전략적 목적을 위해 현재 유전자 변환동물의 생산을 위한 이용에 있어 여러 가지 방법들이 보고되고 있다. 그러나 ES 세포의 사용이 이러한 방법들 사이에서 가장 실질적인 것으로 추정되고 있다. 본 실험에서는 유전자 구축을 위해 사람 황체 호르몬(human luteinizing hormone; hLH)의 전사를 유도하기 위해 각각 2.2 및 0.5 kb의 토끼 $\beta$-casein pronoter 단편을 이용하여 생쥐의 유선에 hLH를 발현시키도록 조절하고 발현이 thynidine kinase(TK) pronoter에 의해 좌우되는 neo 유전자를 selectable marker로서 plasnid속에 삽입하였다. 그 결과 생긴 구축 유전자는 각각 pCas 2.2와 pCas 0.5로 명명하였다. 구축된 유전자로 2$\times$107의 TT-2 ES세포를 170V, 550$\mu$F로 100$\mu$g의 선상 plasmid에 의해 electroporation 시켰다. 감염된 colony들은 250$\mu$g/$m\ell$ G418을 함유하는 ESM 배양액에서 선별 7일 이후에 회수하여 성공적으로 감염된 ES세포는 PCR 및 Southern blot에 의해 확인되었고 그들 중 나머지는 trypsin 처리 후 각각 미세조작과 공배양 기술을 사용하여 ICR 생쥐의 8세포기 수정란 속에 도입하였다. 결국 24시간 동안 37$^{\circ}C$, 5% $CO_2$에서 배양된 배반포를 chimera의 생산을 위해 위임신 유기된 G418 선발처리 이후 400 및 275개의 ES 세포 colony가 생존하였으며, 3개의 ES 세포으 colony 의 genome 속에 임의적으로 plamid가 삽입된 것을 Southern blot에 의해 확인되었다. 총 13 chimera 생쥐가 3 colony로부터 생산되었으나 germ-line chimera는 현재 조사중이다. chimera 생산빈도는 공배양 기술보다 주입방법에서 현저히 높았다.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.343-349
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• 2011

A loosely coupling method is adopted to combine a computational fluid dynamics (CFD) solver and the comprehensive structural dynamics (CSD) code, CAMRAD II, in a systematic manner to correlate the airloads, vortex trajectories, blade motions, and structural loads of the HART I rotor in descending flight condition. A three-dimensional compressible Navier-Stokes solver, KFLOW, using chimera overlapped grids has been used to simulate unsteady flow phenomena over helicopter rotor blades. The number of grids used in the CFD computation is about 24 million for the isolated rotor and about 37.6 million for the rotor-fuselage configuration while keeping the background grid spacing identical as 10% blade chord length. The prediction of blade airloads is compared with the experimental data. The current method predicts reasonably well the BVI phenomena of blade airloads. The vortices generated from the fuselage have an influence on airloads in the 1st and 4th quadrants of rotor disk. It appeared that presence of the pylon cylinder resulted in complex turbulent flow field behind the hub center.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2000.11a
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• pp.88-90
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• 2000

Although primordial germ cells(PGCs) have been used in the production of germline chimera, efficiency has not been satisfactory. The Present study was conducted to improve efficiency of germline chimera production using the cultured gonadal PGCs(gPGCs). Germline chimeric chickens were produced by transfer of cultured gonadal primordial germ cells from Korean Ogol Chicken (KOC) to White Leghorn (5.5-day-old) and cultured in vitro for 10 days. Approximately 200 gPGCs (2-day-old) recipient embryos from which blood had been withdrawn via the dorsal aorta prior to the injection. Recipient embryos were incubated until hatching. Germline chimerism of the chickens reaching maturity was examined by mating them with Korean Ogol Chicken. Donor-derived offspring were identified as germline chimeric chickens based on their feather color. The frequency of germline transmission of donor PGCs ranged 1.9∼60.7%. There was no difference between both sexes. Therefore, it can be concluded that efficiency of germline chimerism can be improved via using cultured gPGCs.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.1-18
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• 2001

A numerical technique for simulating the separation dynamics of strap-on boosters jettisoned in the dense atmosphere is presented. Six degree of freedom rigid body equations of motion are integrated into the three-dimensional unsteady Navier-Stokes solution procedure to determine the dynamic motions of strap-ons. An automated Chimera overlaid grid technique is introduced to achieve maximum efficiency for multi-body dynamic motion and a domain division technique is implemented in order to reduce the computational cost required to find interpolation points in the Chimera grids. The flow solver is validated by comparing the computed results around the Titan IV launch vehicle with experimental data. The complete analysis process is then applied to the. H-II launch vehicle, the central rocket in japans space program, the CZ-3C launch vehicle developed in China and the KSR-III, a three-stage sounding rocket being developed in Korea. From the analyses, separation trajectories of strap-on boosters are predicted and aerodynamic characteristics around the vehicles at every time interval are examined. In addition, separation-impulse devices generally introduced for safe separation of strap-ons are properly modeled in the present paper and the jettisoning force requirements are examined quantitatively.