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Hwang, In-Sun,Park, Mi-Rung,Moon, Hyo-Jin,Shim, Joo-Hyun,Kim, Dong-Hoon,Yang, Byoung-Chul,Ko, Yeoung-Gyu,Yang, Boh-Suk,Cheong, Hee-Tae,Im, GI-Sun The Korean Society of Animal Reproduction 2007 Reproductive & developmental biology Vol.31 No.2
In vitro development of porcine embryo is affected by culture condition. One possible factor is osmolarity of culture medium. 1his study examined whether high osmolarity of culture medium at the early culture stage improves development of preimplantation porcine in vitro fertilization (IVF) and nuclear transfer (NT) embryos. NT and IVF embryos were divided into three groups and the basic medium was PZM-3 ($250{\sim}270$ mOsmol, control group). The control group of embryos was cultured in PZM-3 for whole culture period. Other two groups of embryos were cultured in a modified PZM-3 with 0.05 M sorbitol or 0.05 M sucrose ($300{\sim}320$ mOsmol, sorbitol or sucrose group) for the first 2 days, and then cultured in PZM-3 for further culture. NT embryos cultured in sucrose group showed a significantly higher developmental rate to the blastocyst stage with a decreased apoptosis rate compared to the sorbitol (p<0.05). For IVF, sucrose group showed a significantly increased the blastocyst formation rate with a decreased apoptosis rate compared to the control (p<0.05). This study represents that the high osmolarity in the early embryo culture stage can enhance the in vitro development of porcine NT and IVF embryos to the blastocyst stage with reduced apoptosis of cells.
송석은,황용진,신영철,하대원 진주산업대학교 산업과학기술연구소 1996 산업과학기술연구소보 Vol.- No.3
외력도입에 의한 T형교각 보강검토톨 한 결과 다음과 같은 결론을 내릴 수 있다. 첫째, 철근콘크리트 구조물에 외력도입에 의한 보강은 균열부를 충진제로 마감 후 보강하는 것이 외력에 의한 단면의 응력변화를 명확하게 예측할 수 있다. 둘째, 철근콘크리트 구조물이 허용응력범위내에서는 거의 탄성적으로 거동하는 것으로 간주하고 외력에 의한 응력을 철근콘크리트 이론으로 구할 수 있다. 셋째, 현 2등교 T형 교각을 외력도입에 의하여 1둥교 교각으로 사용할 수 있다. The need for strengthening of existing bridges is a growing concern in many of bridges which were designed for relatively light or inadequate for present traffic. Numerous bridges in Korea are confronted with the problem that bridges constructed between 1960 and 1980 are not in compliance with current legal load. This condition results from increase in legal load limitations, changes in specifications, and increased dead load from resurfacing with concrete overlays. The best solution is to strengthening these existing bridges by prestressing that is an extremely cost-effective method. The basic principle of prestressing is that of the introduction of internal stress of such magnitude and distribution that the stress resulting from given external loadings are counteracted to a desired degree. Focus on this study is rehabilitation of T-shape pier by external posttensioning.
조황래(Hwang-Rae Cho),방정석(Jeong-Suk Bang),이병호(Byung-Ho Rhee),이광진(Kwang-Jin Lee),임병직(Byoungjik Lim),한영민(Yeoung-Min Han),최환석(Hwan-Seok Choi) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11
액체로켓엔진 연소기의 내벽에 사용하기 위한 니켈/크롬 도금 공정 개발을 수행하였다. 열충격 시험을 통해 니켈 도금 조건을 선별하였고 니켈/크롬 도금이 수행된 축소형 연소기의 연소시험을 통해 도금 층의 내구성 검증을 수행하였다. 시험결과 도금 층의 균열 및 박리는 발견되지 않았고, 이 결과로부터 현재 사용중인 대기 플라즈마 용사된 세라믹 코팅의 대안으로 니켈/크롬 도금을 액체로켓엔진 연소기에 사용할 수 있으리라 사료된다. A Ni/Cr plating process has been developed for applying to inner wall of liquid rocket engine(LRE) thrust chamber. Ni plating conditions were selected through thermal shock test and endurance verification of the plating layers was performed through hot firing test of a subscale thrust chamber with Ni/Cr plating. Test results showed that a crack or separation of the plating layers was not found. Judging from the results, Ni/Cr plating could be applied to LRE thrust chamber as a substitute of air plasma sprayed ceramic coating which is presently being used.
In-Sun Hwang,Mi-Rung Park,Hyo-Jin Moon,Joo-Hyun Shim,Dong-Hoon Kim,Byoung-Chul Yang,Yeoung-Gyu Ko,Soh-Suk Yang,Hee-Tae Cheong,Gi-Sun Im 한국동물생명공학회(구 한국동물번식학회) 2007 Reproductive & developmental biology Vol.31 No.2
In vitro development of porcine embryo is affected by culture condition. One possible factor is osmolarity of culture medium. This study examined whether high osmolarity of culture medium at the early culture stage improves development of preimplantation porcine in vitro fertilization (IVF) and nuclear transfer (NT) embryos. NT and IVF embryos were divided into three groups and the basic medium was PZM-3 (250~270 mOsmol, control group). The control group of embryos was cultured in PZM-3 for whole culture period. Other two groups of embryos were cultured in a modified PZM-3 with 0.05 M sorbitol or 0.05 M sucrose (300~320 mOsmol, sorbitol or sucrose group) for the first 2 days, and then cultured in PZM-3 for further culture. NT embryos cultured in sucrose group showed a significantly higher developmental rate to the blastocyst stage with a decreased apoptosis rate compared to the sorbitol (p<0.05). For IVF, sucrose group showed a significantly increased the blastocyst formation rate with a decreased apoptosis rate compared to the control (p<0.05). This study represents that the high osmolarity in the early embryo culture stage can enhance the in vitro development of porcine NT and IVF embryos to the blastocyst stage with reduced apoptosis of cells.
다단연소사이클 엔진 적용을 위한 Ni-Cr 코팅에 관한 연구
배병현(Byung-Hyun Bae),황양진(Yang-Jin Hwang),이규환(Kyu-Hwan Lee),이병호(Byong-ho Rhee),한영민(Yeoung-Min Han),김영준(Young-June Kim),노용오(Yong-Oh Noh),조황래(Hwang-Rae Cho),현성윤(Seong-Yoon Hyun),방정석(Jeong-Suk Bang) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.5
본 논문은 다단연소사이클 엔진의 연소실 내벽을 고온, 고압의 환경으로부터 보호하기 위한 열차폐 코팅 공정 개발에 관한 내용이다. 기존 연소기 내벽에는 열차폐 특성이 우수한 Zr 기반의 세라믹용사코팅을 적용했지만, 세라믹의 특성상 연소실 내벽(금속)과 열팽창계수 차이로 인해 박리가 발생할 수 있다. 때문에 로켓 선진국에서는 열차폐 효과를 다소 희생 하더라도 밀착력 향상을 위하여 금속계 코팅인 Ni-Cr 도금을 적용하고 있다. 본 연구에서는 연소기에 적용 가능한 상향 순환식 유동셀을 적용한 도금조를 개발했으며, 반복적인 공정 개선을 통해 도금 두께 100㎛이상, ±10%의 두께 균일도를 만족하는 Ni, Cr 도금 공정조건을 확립했다. In this paper, the process of electro Ni and electro Cr plating is studied for the purpose of thermal barrier to protect the inner wall combustion chamber. The chamber is under the environment of very high temperature and high pressure when propellants burn in there. As one of the thermal barrier coatings, Zr-based thermal spray coating has been applied to the chamber. However, peeling of coating layer can occur under such a hard condition because of the difference of thermal expansion coefficients between the ceramic and the metallic wall. We study the characteristics of Ni-Cr coating and establish its process. It is found that the thickness of over 100 ㎛ of Ni and Cr coating layers with the uniformity of ±10% can be obtained with the used of as-developed plating bath.
Shim, Joo-Hyun,Kim, Dong-Hoon,Ko, Yeoung-Gyu,Hwang, Seong-Soo,Oh, Keon-Bong,Yang, Boh-Suk,Jin, Dong-Il,Park, Jin-Ki,Im, Gi-Sun The Korean Society of Animal Reproduction 2011 Reproductive & developmental biology Vol.35 No.3
This study investigated whether the addition of porcine sperm cytosolic factor (SCF) at fusion/activation affects in vitro development of porcine parthenogenetic(PA) and nuclear transfer (NT) embryos. To determine the optimum concentration of SCF, control group of oocytes was activated with 0.3M mannitol (1.0 mM $CaCl_2{\cdot}2H_2O$), other three groups of oocytes were parthenogentically activated with the fusion medium (0.1mM $CaCl_2{\cdot}2H_2O$) supplemented with 100, 200 or 300 ${\mu}$g/ml SCF, respectively. Matured oocytes were activated with two electric pulses (DC) of 1.2 kv/cm for 30 ${\mu}$sec. The activated embryos were cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$ for 6 days. Oocytes activated in the presence of SCF showed a significantly higher blastocyst rate than control (p<0.05). Apoptosis rate was significantly lower in 100 ${\mu}$g/ml SCF group than other groups (p<0.05). Cdc2 kinase activity in control and SCF treatment group of oocytes was determined using MESACUP cdc2 kinase assay kit at 1, 5, 10, 15, 30, 45 and 60 min after activation. Cdc2 kinase activity was significantly decreased (p<0.05) in SCF group than MII oocytes or control within 5 min. For NT embryo production, reconstructed oocytes were fused in the fusion medium supplemented with 0.1 mM $CaCl_2{\cdot}2H_2O$ (T1), 1.0 mM $CaCl_2{\cdot}2H_2O$ (T2) and 0.1 mM $CaCl_2{\cdot}2H_2O$ with 100 ${\mu}$g/ml SCF (T3). Fused embryos were cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$ for 6 days. Developmental rate to blastocyst stage was significantly higher in T3 than other groups (23.0% vs. 13.5 to 15.2%) (p<0.05). Apoptosis rate was significantly lower in T3 than T1 or T2 (p<0.05). The relative abundance of Bax-${\alpha}$/Bcl-xl was significantly lower in in vivo or SCF group than that of control (p<0.05). Moreover, the expression of p53 and caspase3 mRNA was significantly lower in in vivo or SCF group than that of control (p<0.05). These results indicate that the addition of SCF at fusion/activation might improve in vitro development of porcine NT embryos through regulating cdc2 kinase level and expression of apoptosis related genes.