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- 저자 : 이장형 ( H . H . Seong (검색결과 4 건)
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성환후,이장형,Seong, H.H.,Lee, J.H. 국립한국농수산대학교 교육개발센터 2002 현장농업연구지 = Journal of practical agricultural resear Vol.4 No.1
This study was conducted to investigate the physiology of optimal reproductive age in Hanwoo for protection to decrease of reproductivity and improvement of production of offspring. Thirty two cows were devided into 4 groups of treatments : T1(12 months of age and 0.5kg daily gain), T2(12 months of age and 0.8kg daily gain), T3(15 months of age and 0.5kg daily gain) and T4(18 months of age and 0.5kg daily gain). The days of the first heat of treated cows were 263.3±6.4 days and average weight was 181.1±11.3kg. The conception rates of first insemination were 25%(T1) and 75%(T4), and the number of insemination of T3 and T4(both 1.5) was lower than those of T1 and T2(2.3 and 2.4), respectively. With regard to estrus return after the first parturition, T1, T2, T3 and T4 showed 66.2,76.7, 62.4 and 68.5 days, respectively, indicating the average days of estrus return was 65.7. Plasma progesterone(P4) concentration was nearly the same during the observation periods of treated cows and P4 began to be detected after 12months. Only 5(15.6%) out of 32cows showed normal estrus cycle and ovulation before 12 months. During the peri-parturition period, P4 concentration was rapidly decreased and there was no detection of P4 from parturition to 40 days after milking. P4 would be released again on 45 day after parturition. The results imply that the optimal reproductive age of Hanwoo heifers would be around at the 14 months of age, 110cm height and 265kg weight.
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Airfoil 주변에서의 층류 및 난류경계층 이론에 대한 수치해석
제두호(Je, Du-Ho),황은성(Hwang, Eun-Seong),이장형(Lee, Jang-Hyeoung) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.4
본 논문에서는 층류 및 난류 유동 특성 중 경계층 두께와 배제 두께, 그리고 모멘텀 두께에 대한 기존의 이론값과 실제 CFD 해석을 통한 수치해석의 데이터를 비교하였다. Freestream velocity는 Reynolds 수에 영향을 주게 되고, airfoil 주변에서의 유동의 층류 및 난류에 영향을 주게 된다. 층류 및 난류의 경우 유동특성이 달라 경계층 두께 및 배제두께, 그리고 모멘텀 두께가 달라지게 되고, 결국 airfoil의 공력특성인 양력과 항력, 그리고 pitching moment에 영향을 주며, separation point도 다양한 angle of attack에서 바뀌게 된다. 이번 연구에서의 목적은 비점성 유동과, 층류 및 난류 각 경우 에 대한 유동특성에 대해 알아보는 것이다. 연구에서 사용된 airfoil의 경우 c=1인 Joukowski airfoil을 사용하였으며, CFD 는 상용 프로그램인 Fluent 6.0을 통해 NACA-0012 airfoil을 사용하였다. 층류 및 난류에서의 Re<sub>c</sub>는 Re<sub>c</sub>=3,000, 700,000 이며 각각에 해당하는 속도는 0.045, 10 m/s이다. 본 연구를 통해 기존의 실험값과 수치해석의 결과가 잘 일치함을 알 수 있으며, 이를 통해 다양한 airfoil의 형상을 모델링할 수 있는 근거를 마련하였다. In the present study, we compared the theory with CFD data about the boundary layer thickness, displacement thickness and momentum thickness. According to the freestream velocity, larminar and turbulent is decided and affect to the flow patterns around the airfoil The boundary layer thickness, displacement thickness and momentum thickness affect to the aerodynamic characteristics of the airfoil(e.g. lift, drag and pitching moment). The separation point is affected by varying angle of attack. In the present study, we used the Joukowski airfoil(c=1), and NACA0012 airfoil was used at CFD. The chord Reynolds number is Re<sub>c</sub>=3,000, 700,000, respectively and the freestream velocity is 0.045, 10 m/s, respectively. In this paper, the data was a good agreement with that of experimental results, so we can analyze the various airfoil models.
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한우에 있어서 발정주기중 혈중 Progesterone 및 Insulin - like Growth Factor-I 농도의 변화
성환후,우제석,임석기,고응규,백광수,박진기,구용범,이장형 ( H . H . Seong,J . S . Woo,S . K . Im,Y . G . Ko,K . S . Baek,J . K . Park,Y . B . Koo,J . H . Lee ) 한국축산학회 1997 한국축산학회지 Vol.39 No.3
The objective of this study was to determine changes in circulating progesterone and insulinlike growth factor-I(IGF-I) concentrations during estrous cycles in Hanwoo. The serum progesterone and IGF-I concentrations during the estrous cycles in the apparently healthy normal cycles and freemartins of 670 days old were measured with a commercial Radio Immuno Assay(RIA) kit. Serum progesterone concentration was low from Day 1 to 3(about 0.25ng/㎖) and then increased gradually to 9.3ng/㎖ by Day 17, and decreased dramatically by Day 21 of the estrous cycle. However, serum progesterone concentration of freemartins was almost undetectable during the same periods of normal Hanwoo. Serum IGF-I concentrations from Day 3 to 16 of normal estrous cycle were higher than those of early luteal stage( Day 1∼2) and luteal regression stage (Day 19∼20). The lowest serum IGF-I concentration was observed on Day 21. In the freemartin of Hanwoo, serum IGF-I concentrations were 1/4 of those in the normal cycles. It is suggested that the serum progesterone concentration is closely related to the serum IGF-I concentration in Hanwoo.
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