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저밀도 폴리에틸렌에서 부시형 전기트리에 수반되는 부분방전 펄스의 특성
강성화,박영국,정수현,이광우,임기조 한국전기전자재료학회 1998 전기전자재료학회논문지 Vol.11 No.12
The correlation between the propagation of electrical tree and distributions of partial discharge(PD) pulses accompanying with electrical tree of bush type in low density polyethylene were discussed. We measured the growth of electrical tree by using optical microscope and PD data simultaneously. The PD data detected and analyzed were PD magnitude, repetition rate, average discharge power, average phase angle, and $\psi$-q-n distribution pattern. The average discharge power and repetition rate of PD had good linear relation with area of tree. Repetition rate and peak discharge magnitude and width of discharge phase angle increased with the tree.
동화를 이용한 프로그램 유형이 4·5 세 유아의 창의성 증진에 미치는 효과
강성화,이정화 미래유아교육학회 2001 미래유아교육학회지 Vol.8 No.2
The purpose of this study was to examine the effects of two kinds of story based activity (dramatic play and retelling) programs on 4- and 5-year-old children's creativity. Three questions were made from the review of the literature, as follows; 1) Is there a difference in the gaining scores of creativity between children in the dramatic play and retelling program? 2) Is there a difference in the gaining scores of creativity between four- and five-year-old children? 3) Is there any interaction effect of program by age for the gaining scores of creativity? To answer the research questions, two kinds of story based activity program(dramatic play program and retelling program) were designed to facilitate children's creativity. A total of 60 children(30 of four-year-old, 30 of five-year-old) enrolled in a preschool in Busan participated as subjects. The subjects were randomly assigned to either a dramatic play program or a retelling program. Children in the dramatic play program were participated in 8 50-minute sessions of dramatic play, whereas children in the retelling program took part in 8 50-minute sessions of retelling activity. After the sessions of each program, all children were individually tested on the K-CCTYC(Korean Comprehensive Creativity Test for Young Children). The data were analyzed in 2 (program) X 2 (age) ANOVAs using SPSS/PC+. The results of this study can be summarized as follows. First, there was no significant difference in the gaining scores of the K-CCTYC between children in the dramatic play and retelling program. Second, a significant difference was found in the gaining scores of the K-CCTYC between 4- and 5-year-old children. The gaining scores of K-CCTYC made by four-year-old children were significantly higher than those by five-year-old children. Third, no significant interaction effect of program by age was observed. The results of this study indicate that both the two programs worked more positively on four-year-old children than five-year-old children.
전기절연유의 절연파괴에 미치는 전극간격 및 곡률반경의 영향
강성화,채홍인,이종필,임기조 한국안전학회 2004 한국안전학회지 Vol.19 No.1
In this paper, we investigated the influence of gap length and tip radius on breakdown of mineral based insulation oil. Applied voltages were DC and AC voltage. Electrode system was needle-plane structure. The tip radius of needle electrode was 5, 10, 20 and 25μm, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. Electric breakdown strength at tip was calculated using Mason's equation contained geometric figure. As gap length increased, breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by the phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage, breakdown strength was higher when polarity of needle was negative than positive. It is because of the space charge effect in accordance with the influence of liquid motion.