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과배란 유도시 혈청 Estradiol 및 Prolactin치의 동태에 관한 연구
신영관,이진용,Shin, Young-Kwan,Lee, Jin-Yong 대한생식의학회 1987 Clinical and Experimental Reproductive Medicine Vol.14 No.1
It appears that a major determinant of the success of in vitro fertilization is the selection of the optimal follicle containing an oocyte capable of being fertilized and producing a normal pregnancy. However, the hormonal basis of oocyte maturation is not well substantiated by the as yet available informations. It has been suggested that prolactin(PRL) may stimulate the formation of an oocyte maturation inhibitor and thus inhibit the maturation of oocyte. During the hyperstimulated menstrual cycles serum estradiol($E_2$) levels are markedly elevated, and it seems justified to assume that serum prolactin levels may be elevated since estrogens are potent stimulators of prolactin secretion. This study was carried out to ascertain the effect of the elevated serum estradiol levels on the serum prolactin levels in women undergoing ovarian hyperstimulation with either hMG and/or clomiphene citrate. Serum estradiol and prolactin profiles were measured from third menatrual cycle day to ovulation or ovum aspiration day in 11 normal menstruating women and 30 women who underwent an in vitro fertilization procedure with ovarian hyperstimulation by hMG, clomiphene citrate/hMG, clomiphene citrate. Ovum aspiration was performed 36 hours after hCG administration. The day of ovum aspiration or ovulation was designated Day 0. Serum estradiol levels increased progressively during the follicular phase and this rise peaked on Day-1 at a mean concentration of 1,204${\pm}$189.0pg/ml in Group II(hMG), 1,194${\pm}$167.9pg/ml in Group III(clomiphene citrate/hMG), 1,035${\pm}$195.1pg/ml in Group IV(clomiphene citrate) respectively and on Day -2 of 336${\pm}$34.5pg/ml in Group I(normal control). The elevated estradiol levels fen rapidly after ovulation or ovum aspiration. Serum estradiol values of hyperstimulated groups(Group II, III, IV) were significantly higher than that of control group(Group I) from Day -6 to Day +1, but there was no significant difference of estradiol values among the hyperstimulated groups. Serum prolactin levels increased and peaked on Day +1 at a mean concentration of 60.8${\pm}$14.4ng/ml in Group II, 34.2${\pm}$7.0ng/ml in Group III, 30.1${\pm}$5.7ng/ml in Group IV respectively, but no significant elevation was observed in Group I. Levels of estradiol and prolactin can be positively and significantly correlated in the hyperstimulated groups. However, the increase of serum prolactin levels in hMG group was significantly higher than those in clomiphene citrate/hMG or clomiphene citrate group.
A Study on the Machinability of Tungsten Carbide Using Ultrafast Laser
신영관(Young Gwan Shin),최원석(Wonsuk Choi),김훈영(Hoon Young Kim),조성학(Sung-Hak Cho) Korean Society for Precision Engineering 2020 한국정밀공학회지 Vol.37 No.10
The tungsten carbide is a material with high hardness, wear resistance, good chemical stability, and dimensional stability. Because of these characteristics, it is mainly used as a tool for cutting and molding such as molds, and casts required for manufacturing high value-added equipment such as automobile parts and medical equipment. However, it is difficult to process with the traditional machining methods because of the high toughness and hardness. To overcome these problems, a study of tungsten carbide machining processing using the ultrafast-laser was recently conducted. In this paper, the ultrafast lasers with the pulse duration of 190 fs, 5 and 10 ps, respectively, were used. When the experiments were conducted with pulse widths of 5 and 10 ps, respectively, micro-cracks were observed from the heat generated by the overlap of the laser pulses. Conversely, the machining processing using a laser with the pulse width of 190 fs showed a major advantage with no crack by minimizing the thermal effects.