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고출력 CW Nd:YAG 레이저를 이용한 인코넬 600의 용접 특성
유영태,신호준,임기건 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.6
The welding characteristics of Inconel 600 Alloy using a continuous wave Nd:YAG laser are experimentally investigated. The major process parameters studied in the present laser welding experiment were the positions of focus, laser power and travel speed of laser beam. We measured the fusion zone size and its shape using an optical microscope for the observation of cross-sectional area. We performed two tests regarding the tension and the micro hardness for welding quality estimation. Then we measured residual stress in welds by electronic speckle pattern interferometry(ESPI). In conclusion, the optimum butt welding process parameters were 0.5mm focus position, 1.6kW laser power, 1m/min travel speed and 5.5ℓ/min assist gas discharge.
신호준,유영태,임기건,안동규 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-
For many years and primarily for economical reasons, Dissimilar Metal Welds have been used as transition joints in a variety of equipment and applications. But Dissimilar Metal Welds have several fabrication and metallurgical drawbacks that can often lead to in-service failures. In this paper, the laser weldability of STS304 stainless steel and SM45C at dissimilar metal welds using a continuous wave Nd:YAG laser are experimentally investigated. An experimental study was conducted to determine effects of welding parameters, on eliminating or reducing the extent welding zone formation at dissimilar metal welds and to optimize those parameters that have the most influence parameters such as focus length, power, beam speed, shielding gas, and wave length of laser were tested.
신호준,유영태,안동규,임기건 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-
Laser surface hardening is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power CO₂ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self quenching to occur and the formation of martensitic structure. In this investigation, the microstructure features occurring in Nd:YAG laser hardening SM45C steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimism of the processing parameters for maximum hardened depth of SM45C steel specimens of 3mm thickness by using CW Nd:YAG laser. Travel speed was varied from 0.6m/min to 1.0m/min. The maximum hardness and case depth fo SM45C steel are 780Hv and 0.4mm by laser hardening.
호르몬 보충용법이 단구세포의 조직인자 활동에 미치는 영향
민부기,김홍곤,김기석,홍기연,이희섭 대한폐경학회 1998 대한폐경학회지 Vol.4 No.1
"Our purpose was to investigate the effects of hormone replacement therapy on the reactivity of monocyte in whole blood, mesured by tissue factor activity. Thirty-eight women were randomized into oral combind homone replacement therapy and underwent blood sampling before and 3 and 12 months of treament,The tissue factor activity in monocytes was measured both in unstimulated whole blood and after a weak lipopolisaccaide stimulation. After 12months of hormone replacement therapy there were significant reduction of tissue factor activity in both unstimulated and lipopolisaccaride stimulated monocyte (p<0.001). Twelve months of hormone replacement therapy reduces cellular activation of blood monocytes; these changes may account for some of the beneficial effects in reducing the risk of cardiovascular disease. "
인간 난관세포와의 체외 공동배양과정에서 혈소판 활성요소가 생쥐배의 발달에 미치는영향
민부기,김기석,이희섭,홍기연,김흥곤,신무철,이찬근,최은하,Min, Bu-Kie,Kim, Kie-Seok,Lee, Hee-Sup,Hong, Kie-Youn,Kim, Heung-Gon,Shin, Mu-Cheol,Lee, Chan-Kun,Choi, Eun-Ha 대한생식의학회 1996 Clinical and Experimental Reproductive Medicine Vol.23 No.1
There are a number of problems during the process of culture in vitro on fertilization and embryo development compared to those on in vivo counterparts. And the platelet activating factor (PAF), which is found not only in mammalian spermatozoa but also preembryos, is implicated on reproductive process. To improve the environment of culture on in vitro fertilization and embryo development, coculture using salpingeal epithelial cells has been considered to accept the better result on pregnancy rate. This study was designed to determine if two different culture systems, coculture alone and PAF treated coculture, are positive or negative influence on process of in vitro fertilization and embryo culture in mouse. The cell cleavage rate reached to 2-4 cell stage at 24 hours of culture is 56.81% (50/88) and 48.21%(54/112) respectively, in PAF treated group which is added PAF on coculture and in coculture group. But the rate of cells cleavage was similar in both group after 48 hours of culture. The rate of unfertilization after insemination of oocytes was higher in coculture group(55..53%) than in PAF treated group(42.37%). And in assessment of undeveped embryos, the rate of equalized cell block was similar on both, coculture alone (35.3%)and PAF treated coculture(35.5%). while unequalized cell block was higher rate in PAF treated coculture(19.4%) than coculture alone (11.8%). But the rate of cytoplasmic degeneration of undeveloped embryos was significantly higher in PAF treated coculture than coculture alone. In conclusion, we have observed that PAF treated coculture is superior in the rates of in vitro fertilization and early embryo cell cleavage compared to those in coculture alone, but there is no difference on the rates of embryo develpments, cell degeneration, cell quality in both PAF treated coculture and coculture alone when the embryo cells were continuosly cultured for 48 hours or more.
자궁내막증 치료 전후 환자의 혈청이 생쥐 난자의 수정률에 미치는 영향
김기석,민부기,이희섭,홍기연,이선영,박현진,김흥곤,Kim, Kie-Suck,Min, Bu-Kie,Rhee, Hee-Sub,Hong, Kie-Youn,Lee, Sun-Young,Park, Heon-Jin,Kim, Heung-Gon 대한생식의학회 1999 Clinical and Experimental Reproductive Medicine Vol.26 No.3
Objective: To evaluate the effect of serum obtained before and after treatment for endometriosis on in vitro fertilization and development of two cell mouse embryo. Design: Pretreatment and posttreatment comparoson of fertilization of mouse oocyte and embryo development in serum supplement from patients with endometriosis; result were compared using Stuent T-test analysis. Method: Infertility Clinic, Department of Obstetrics and Gynecology, Collage of Medicine, Won kwang university, Korea. Patients was chosed eleven consecutive women with endometriosis. Interventions was all patient underwent laparoscopic or conservative surgery. This was followed by a 6-month course of burserelin acetate $900{\mu}g/d$. Main outcome was measured total number of fertilization and embryo that was fertilization after 24 hours and reached blastocyst stage after 72 hours of incubation were compared before and after treatment. Result: Before treatment, 47% of the oocyte were fertilized and 31% of the embryo reached blastocyst stage. After treatment, Significantly more fertilized and Significantly more embryo developed to blastocyst on the stage I and II of endometriosis. Conclusion: The fertilization and embryo toxicity of serum samples from patients with endometriosis is lost after treatment.
Subcloning and Sequencing of β-Xylosidase Gene of Alkalophilic Bacillus sp. K17
SUNG, NACK KIE,SHIM, KI HWAN,CHUN, HYO GON,CHUNG, CHUNG HEE,CHUNG, YOUNG CHUL,KO, HAK RYONG 경상대학교 유전공학연구소 1988 遺傳工學硏究所報 Vol.7 No.-
The 5.0kb insert of pAX278, which was previously cloned, was reduced by various deletion and thus I. 4kb EcoRI-XbaI fragment was recloned into pUC19(pAK208). To increase β-xylosidase activity, the I. 4kb insert in pAK208 was recloned into expression vector, pKK223-3 (tac-promoter), and β-xylosidase activity in cell carring this plasmid (pKHR212) was increased was 3.5 times than that in pAX278. The complete nucleotide sequence of thermophilic alkalopilic Bacillus sp. K17 and its flanking regions were established. A 1263-bp open reading frame for β-xylosidase was observed. The molecular weight(50, 521 dalton) deduced from for β-xylosidase gene, was agreed with the result obtained by SDS-polyacry-lamide gel electrophoresis of the purified enzyme. The Shine-Dalgarno sequence was found-8 bp upstream of the initiation codon ATG. The 1-10 regions for promotor sequence of β-xylosidase gene were similar to the consensus sequence for B. subtilis RNA polymerase, and the-35 regions were different from all the known promotor for B. subtilis RNA polymerase.
SUNG, NACK KIE,SHIM, KI HWAN,CHUNG, DUCK HWA,CHUN, HYO GON,HUR, SUNG HO 경상대학교 유전공학연구소 1986 遺傳工學硏究所報 Vol.5 No.-
The extracellular xylanase produced by E. coli HB101 carrying pAX113, which contains the xylanase I gene of thermophilic alkalophilic Bacillus K-17, was purified by ammonium sulfate precipitation, DEAE-Sephadex A-50 column chromatography, CM-Sepadex C-50 column chromatograhy and Sephadex G-100 gel filtration. The purified enzyme had a molecular weight of 23,000. The pH and temperature optima for its activities were 6.5 and 65℃, respectively. The enzyme retained full activity after incubation at 60℃ for 1hr or at pH 5-9 for 24 hr. The Km value of the enzyme was 4.65 mg-xylan/ml. These enzymatic properties of the xylanase were almost the same as those of xylanase I. Furthermore, we could purify a larger amount of xylanase from E. coli than from thermophilic alkalophilic BacillusK-17.