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$Na_2O-Fe2O_3-B_2O_3-P_2O_5$ 계 유리의 도전성에 관한 연구
박용원,이경태 한국세라믹학회 1985 한국세라믹학회지 Vol.22 No.3
The composition of the base glass was determined to be $Na_2O$ 15, $Fe_2O_3$ 35, $B_2O_3$ 0~20, $P_2O_5$ 30~50 by mole percent. The heating temperature for nucleation was determined by means of thermal expansion curve. Crystalline phases were investigated by X-ray diffraction method and I.R Spectra. Electrical conductivities of glass spec-imens were observed in the temperature range 25~20$0^{\circ}C$ The activation energies of these specimens were caculated. The results obtained were as follows : 1) The limit composition of the melts 15mol% $Na_2O$ 35mole% $Fe_2O_5$ 20mole% $B_2O_3$ 30mole% $P_2O_5$ was able to be formed into desired shapes during cooling, . 2) In the measurement of d. c conductivity($\delta$) on the glasses in the system $15Na_2O-35Fe_2O_3$-$B_2O_3$-(50-x) $P_2O_5$ the values decreased by replacing 5 mole% $P_2O_5$ with $B_2O_3$ 3) The d. c conducties of heat treated samples were increased by replacing $P_2O_5$ with $B_2O_3$ 4) $B_2O_3$ contributed to precipitate crystals such as${\gamma}$-$Fe_2O_3$ $Fe_3O_4$ which had the advantage of electronic conduction in heat treated samples. 5) The slope plotted Log($\delta$) versus 1/T in this glass system was linear in the measured temperature range.
자궁태반 기능부전증의 예측에 있어 Doppler 초음파검사의 유용성
박용원,조재성,김태윤,최형민,김경수,임영구 대한산부인과학회 1997 Obstetrics & Gynecology Science Vol.40 No.5
This study was designed to investigate a possible role for Doppler velocimetry as a predictor of uteroplacental insufficiency with fetal heart rate(FHR) tracing. From January 1994 to through May 1996, we studied 419 high risk pregnant women who underwent Doppler velocimetry within 1 week of intrapartum cardiotocogram or contraction stress test (CST) after 30 gestational weeks. The presence of a diastolic notch in uterine artery, elevated systolic/diastolic(S/D) ratios in umbilical artery(more than 3.0), or in uterine artery (more than 2.6) were considered abnormal. All of the 419 subjects were performed intrapartum cardiotocogram or CST within 1 week after Doppler veocimetry. Seventeen cases were associated with persistent late deceleration or positive CST. The sensitivity, specificity, positive predictive value, negative predictive value, and relative risk of umbilical artery S/D ratio for predicting abnormal FHR tracing were 23.5%(4/17), 89.3%(359/402), 8.5%(4/ 47), 96.5%(359/372), and 0.97. those of uterine artery S/D ratio and diastolic notch were 29.4%(5/17), 92.5%(372/402), 14.3%(5/35), 96.9%(372/384), 1.35 and 35.3%(6/17), 90.3% (363/402), 13.3%(6/45), 97.6%(363/374), 3.88 respectively. The presence of uterine artery diastolic notch in Doppler velocimetry seems to be a better predictor for abnormal FHR tracing after 30 weeks gestation than are S/D ratios in umbilical or uterine arteries. In conclusion, we can suggest that the presence of diastolic notch in uterine artery Doppler velocimetry might be useful to predict the uteroplacental insufficiency after 30 gestational weeks.