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김이영,김수길,한종희,김한성,Kim, Yi-Young,Kim, Soo-Kil,Han, Jong-Hee,Kim, Han-Sung 한국전기화학회 2008 한국전기화학회지 Vol.11 No.2
에탄올이 이산화탄소가 생성되는 경로로 반응할 경우 12개의 전자를 발생시키게 되지만 실제로는 두 개의 탄소 원자사이의 결합력 때문에 완전 산화시키는 것이 쉽지 않다. 따라서 고성능 에탄을 산화촉매의 개발은 에탄을 연료전지 실용화에 필수적이다. 본 연구는 Pt에 Sn, Au을 첨가하여 이원계, 삼원계 촉매를 제조하여 에탄올에서의 활성과 촉매의 특성에 대한 분석을 수행하였다. 촉매합성은 modified polyol 방법을 이용하였으며 Vulcan XC-72R 담지체를 사용하여 20 wt%로 담지하였다. PtSn/c 합금촉매는 Pt : Sn의 비율이 1 : 0, 4 : 1, 3 : 1, 2 : 1, 1.5 : 1, 1 : 1, 1 : 1.5으로 합성하였으며, PtSnAu/C 합금촉매는 Pt : Sn : Au의 비율을 5 : 5 : 0, 5 : 4 : 1, 5 : 3 : 2, 5 : 2 : 3으로 합성하였다. 촉매특성은 XRD, TEM 분석을 통해 분석한 결과 $1.9{\sim}2.4\;nm$ 정도의 입자의 크기와 면심입방구조의 구조를 가지는 것으로 확인하였다. 에탄올 산화에 대한 합금촉매의 활성은 순환전류전압법으로 실험하였고, 그 중 가장 높은 성능을 가진 PtSn(1.5 : 1)/C와 PtSnAu(5 : 2 : 3)/C 합금촉매를 단위전지 성능평가륵 통해 실제 연료전지 구동환경에서 촉매의 활성을 측정하였다. 그 결과 에탄을 산화에 가장 높은 성능을 나타낸 촉매는 PtSn/c(1.5 : 1)이었고, 촉매의 안정성은 PtSnAu/C(5 : 2 : 3)에서 높게 나타났다. Though ethanol can theoretically generate 12 electrons during oxidation to carbon dioxide, the complete oxidation of ethanol is hard to achieve due to the strong bond between the two carbons in its molecular structure. Therefore, development of high activity catalyst for ethanol oxidation is necessary for the commercialization of direct ethanol fuel cell. In this study, some binary and ternary electrocatalysts of PtSn/C and PtSnAu/C have been synthesized and characterized. The catalysts were fabricated with modified polyol method with the amounts of 20 wt%, where the Pt : Sn ratios in the PtSn/C were 1 : 0, 4 : 1, 3 : 1, 2 : 1, 1.5 : 1, 1 : 1, 1 : 1.5 and Pt:Sn:Au ratios in the PtSnAu/C were 5 : 5 : 0, 5 : 4 : 1, 5 : 3 : 2, 5 : 2 : 3. From the XRD and TEM analysis results, the catalysts were found to have face centered cubic structure with particle size of around $1.9{\sim}2.4\;nm$. The activity in the ethanol oxidation was examined with cyclic voltammetry and the results indicated that PtSn(1.5 : 1)/C and PtSnAu(5 : 2 : 3)/C had the highest activity in each catalyst system. Further tests with single cell were performed with those catalysts. It was found that PtSn/C(1.5 : 1) exhibited the best performance while the long term stability of PtSnAu/C(5 : 2 : 3) is better than PtSn/C(1.5 : 1).
1인 1회 분량을 적용한 영양 섭취량 추정 타당도 평가
김이영,김미현,최미경,Kim, Yi-Yeong,Kim, Mi-Hyun,Choi, Mi-Kyeong 한국식품영양학회 2015 韓國食品營養學會誌 Vol.28 No.5
24-hour recall is the dietary assessment method most frequently used to evaluate dietary intake; however, accuracy is an issue when using this method, especially in large-scale studies. The purpose of this study was to assess the validity of dietary intake estimation using one serving size. Estimates of energy and nutrients taken in over a 24-hr period based on actual intake amount (24HRAI) and based on estimates of one serving size (24HRSS) were compared. Data were analyzed using a paired t-test, Pearson's correlation coefficients, and a cross-classification method. In male subjects, intake levels of energy, fat, vitamin C, vitamin $B_1$, Zn, and total food measured using 24HRAI were significantly higher than those measured using 24HRSS. In female subjects, intake of carbohydrates, fiber, fat, vitamin A, vitamin C, vitamin B complexes, various minerals, and total food measured using 24HRAI were significantly lower than those measured using 24HRSS. Energy-adjusted Pearson's correlation coefficients revealed that intake of all nutrients showed a significant positive relationship between the two measurement methods in both males and females. Cross-classification analysis revealed that 50.5~67.6% of women and 40.3~71% of men were classified in the same quartile of intake of each nutrient when comparing data from 24HRAI and 24HRSS. We conclude that using one serving size in 24-hr recall analysis was valid and therefore may be used in studies to assess food consumption in the general adult population. Also, this method can be used to classify energy and nutrient intake into quartile, which is useful in examining the association between diet and chronic diseases.
청소년의 그릿과 학업성취도의 관계에서 자아존중감의 매개효과와 사회적 자본의 조절효과
김이영 ( Yiyoung Kim ) 사단법인 아시아문화학술원 2021 인문사회 21 Vol.12 No.2
본 연구는 중학생의 그릿, 자아존중감, 사회적 자본, 학업성취도의 관계를 파악하는데 그 목적이 있다. 연구대상은 한국아동청소년패널조사 2018 1차년도 데이터의 중학교 1학년 2,500명이다. 자료 처리는 SPSS 23.0 프로그램을 활용하여 빈도분석, 기술통계분석, 상관관계분석을 하였고, PROCESS MACRO 3.5를 사용하여 매개분석, 조절효과를 분석하였다. 본 연구에 대한 결과는 다음과 같다. 첫째. 청소년의 그릿과 학업성취도의 관계에서 자아존중감의 매개효과를 확인하였다. 둘째, 청소년의 그릿과 학업성취도의 관계에서 사회적 자본 중 친구관계의 조절효과를 확인하였다. 이러한 연구결과를 통해 그릿, 자아존중감, 사회적자본, 학업성취도의 관계에서 중학생의 학업성취도를 높이기 위한 교육적 개입에 대하여 논의하였다. The purpose of this study is to understand the relationship between grit, self-esteem, social capital, and academic achievement of middle school students. The subjects of this study are 2,500 first-year middle school students according to the data for the first year of the Korean Child and Youth Panel Survey 2018. For data processing, frequency analysis, descriptive statistics analysis, and correlation analysis were performed using SPSS 23.0 and mediated analysis and control effects were analyzed using PROCESS MACRO 3.5. The results of this study are as follows. First. The mediating effect of self-esteem was confirmed in the relationship between adolescents’ grit and academic achievement. Second, in the relationship between adolescent’s grit and academic achievement, the moderating effect of the friend relationship among social capital was confirmed. Through these research results, educational interventions were discussed to increase the academic achievement of middle school students in the relationship between grit, self-esteem, social capital, and academic achievement.