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보존형 형태의 S-A 난류 모델 방정식을 이용한 이차원 유동 해석
곽인근(E. Kwak),백지영(J.Y. Baek),이승수(S. Lee) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
Numerical simulations of two dimensional flows are performed with a conservative form of S-A turbulence model and the simulation results are compared to those of the standard form and the compressible form. The conservative form is derived, from the standard form, which is in non-conservative form, using the continuity equation. The model constant of the conservative form is corrected to compensate for the differences between the conservative and the non-conservative discretizations. For verification of the conservative form of the equation, flows over a flat plate at various flow conditions are computed and the results are compared to those of the other forms as well as other computational results and theories. For subsonic flows, little difference is observed between the results of three forms. For supersonic and hypersonic flows, however, skin frictions of the compressible form and the conservative form are slightly larger than that of the standard form. Furthermore, numerical simulations of a transonic flow around an airfoil are performed with three forms and usefulness of the conservative form is confirmed by obtaining reasonable results.
축대칭 초음속 흡입구 주위의 저주파수 및 고주파수 버즈(Buzz) 에 대한 수치모사
곽인근(E. Kwak),이승수(S. Lee) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
In this paper, numerical simulations of both low- and high-frequency buzz phenomena at the throttle ratio (T.R.) found in Nagashimas experiment are performed. The dominant frequencies of low- and high- frequency buzz in the experiment are about 109 Hz with T.R.=0.97 and 376 Hz with T.R,=0.55, respectively. An axisymmetric solver with the S-A turbulence model and the SST turbulence model is used in the simulations and DFT on pressure histories is conducted for the buzz frequency analysis. In the present simulations, the free-stream Mach number and the Reynolds number bases on the inlet diameter are 2 and 10<SUP>7</SUP>, respectively. Both low- and high-frequency buzz phenomena are simulated successfully without changes in the grid topology. The dominant frequency of the simulation is about 125 Hz with T.R.=0.97, while it is 399 Hz with T.R.=0.55.
축대칭 초음속 흡입구 주위의 저주파수 및 고주파수 버즈(Buzz)에 대한 수치모사
곽인근(E. Kwak),이남훈(N. Lee),공효준(H. Gong),이승수(S. Lee) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.2
In this paper, numerical simulations of both low- and high-frequency buzz phenomena at the throttle ratios (T.R.) in Nagashimas experiment are performed. The dominant frequencies of the low-and high-frequency buzz in the experiment are about 109 Hz with T.R.=0.97 and 376 Hz with T.R.=0.55, respectively. An axisymmetric solver with the S-A turbulence model is used for the simulations, and DFT(Discrete Fourier Transform) on pressure histories is conducted for the buzz frequency analysis. In the present simulations, the free-stream Mach number and the Reynolds number based on the inlet diameter are 2 and 107, respectively. Both the low- and high-frequency buzz phenomena are accomplished without the changes in the grid topology. The dominant frequency of the simulation is about 125 Hz with T.R.=0.97, while it is 399 Hz with T.R.=0.55.
닭의 CaSR 유전자내 단일 염기 변이 탐색 및 경제 형질간의 연관성 분석
홍윤숙,오재돈,이제현,공홍식,최철환,이승수,전광주,이학교,Hong, Y.S.,Oh, J.D.,Lee, J.H.,Kong, H.S.,Choi, C.H.,Lee, S.S.,Jeon, G.J.,Lee, H.K. 한국가금학회 2007 韓國家禽學會誌 Vol.34 No.2
Calcium Sensing Recepter(CaSR) 유전자는 세포의 밖에서 칼슘의 항상성을 조절하는 역할을 담당하며, 부갑상선 호르몬의 분비를 조절하고 비뇨기에서 칼슘의 흡수를 담당하는 것으로 알려져 있다. CaSR 유전다의 체내 칼슘 농도 조절 기작은 동물의 여러 경제 형질에 영향을 미칠 것으로 추정되며 경제 형질 개량에 강력한 후보 유전자로서 가능성이 잠재되어 있다. 따라서 본 연구는 닭의 CaSR 유전자 내 염기 변이 지역을 탐색하고 이를 통해 검출된 변이 지역과 경제 형질간의 연관성을 규명하고자 실시하였다. 한국 재래닭의 AS 유전자형이 65%로 가장 높은 출현 빈도를 보였으며, SS 유전자형이 23%, AA 유전자형이 12%로 나타났다. 반면, 레그혼 품종에서는 AS 유전자형이 92%로 높은 빈도를 나타냈으며, AA 유전자형이 0.8%의 빈도를 보였다. 그리고 레그혼 품종에서 SS 유전자형은 발견되지 않았다. A963S 유전자형과 경제 형질간의 연관성 분석 결과를 레그혼 집단에서 분석된 결과에 따르면 시산일령에서 유전자형과의 유의한 연관성이 검출되었다. $AA(137.6{\pm}2.63)$ 유전자형은 $AS(143.0{\pm}1.60)$ 유전자형보다 빠른 시산일령을 가진 것으로 나타났다. 한국 재래닭 집단에서 분석된 결과에 따르면 시산일령과 난중에서 유전자형과의 유의한 연관성이 검출되었다. 시산일령의 경우 $AA(151.0{\pm}2.87)$와 $AS(152.6{\pm}1.21)$ 유전자형은 $SS(159.43{\pm}2.03)$ 유전자형보다 빠른 것으로 나타났으며, 난중은 $SS(50.4{\pm}0.81)$유전자형이 $AA(47.5{\pm}1.15)$와 $AS(47.85{\pm}0.49)$유전자형보다 무거운 것으로 나타났다. 본 연구의 결과 A963S 지역의 변이가 칼슘 농도의 조절에 영향을 미치고 이에 따른 프로게스테론이나 성장 호르몬 등의 분비에 영향을 미쳐 결과적으로 시산일령과의 유의적인 연관성이 나타난 것으로 추정된다. 대립 유전자 A를 분자 생물학적 마커로 이용하여 경제 형질중 산란일령을 앞당기는데 큰 기여를 할 수 있을 것으로 기대된다. The Function of the calcium sensing receptor (CaSR) is to control calcium levels by altering PTH (parathyroid hormone) secretion and renal calcium resorption. The influence of calcium on the basal and stimulated release of several hormones from chicken pituitary glands has been determined in vitro. The objective of this study was to identify SNP in chicken CaSR gene and to investigate the effect of the SNP on economic traits. The sequencing analysis method was used to identify nucleotide polymorphisms within chicken CaSR gene. This study identified SNP at position 1949 bp(Genebank accession No : XM_416491) in the exon 1. The SNP changed the amino acid to alanine(GCC) from serine(TCC). This SNP showed three genotypes, AA, AS and SS by digestion with the restriction enzyme NcoⅠ using the PCR-RFLP method. The A963S showed significant effect only on the first lay day (P<0.05) in Leghorn population. Leghorn with the genotype AA had significantly faster the first lay day(137.6) than the genotype AS(143.0, P<0.05). Also, the A963S showed significant effect only on the first lay day(P<0.05) and mean of egg weight(P<0.05) in KNC population. KNC with the genotypes AA ans AS had significantly faster the first lay day (151.0 and 152.6, respectively) than the genotype SS(159.4, P<0.05). And the genotypes SS had significantly heavier the mean of egg weight(50.4 kg, P<0.05) than the genotype AA ans AS (47.5 and 47.8 kg, respectively). According to result of this study, an a allele of the A963S was found to have a significant effect on the first lay day. It will be possible to use this SNP marker on selecting chicken to improve the first lay day.
Chimera 격자계를 이용한 Euler/Navier-Stokes Solver의 개발
이승수(S. Lee),박민우(M. Park),조금원(K. W. Cho),권장혁(J. H. Kwon) 한국전산유체공학회 1998 한국전산유체공학회 학술대회논문집 Vol.1998 No.-
An Euler/Navier Stokes solver has been developed for the analysis of steady and unsteady flows. The q-ω turbulent model has been incorporated into the solver in strongly coupled manner for stability and robustness. A new Chimera hole cutting algorithm, Cut-paste algorithm, has been devised for automatic Chimera hole cutting. Number of viscous/inviscid numerical computations demonstrate the accuracy and the versatility of the solver.
비선형 점성유체의 다상유동 모형을 이용한 토석류 전산해석
이승수(S. Lee),황규관(K.K. Hwnag) 한국전산유체공학회 2017 한국전산유체공학회지 Vol.22 No.1
Debris flow is a composition of solid objects of various sizes, suspension and water, which occurs frequently as the results of landslide following heavy rainfall. This often causes extensive damage in the form of socio-economic losses and casualties as witnessed during the incident around Mt. Umyeon, Seoul in 2011. There have been numerous investigation to mitigate the impacts from debris flow; however, the estimation as preparedness measure has not been successful due to nonlinear and multiphase characteristics of phenomena both in material and process inherent in the debris flow. This study presents a numerical approach to simulate the debris flow using open source code of computational fluid dynamics, OpenFOAM with non-Newtonian viscosity model for three phase material modeling. In order to validate the proposed numerical method, the quantitative evaluations were made by comparisons with experimental results and qualitative analysis for the dispersion characteristics was carried for the case of debris flow in the actual incident from Mt. Umyeon.