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$Al_2O_3-ZrO_2-SiC$ Whisker 복합재료에서의 R-curve 거동에 관한 연구
김현하,박현,최성철,Kim, Hyun-Ha,Park, Hyun,Choi,Sung-Churl 한국세라믹학회 1993 한국세라믹학회지 Vol.30 No.9
R-curve measurements were performed on Al2O3(matrix)-ZrO2-SiC whisker composite and Al2O3-ZrO2, Al2O3-SiC whisker composites in the favor of comparing the effect of ZrO2 and SiC whisker, as a second phase, to Al2O3 matrix. Al2O3-SiC whisker and Al2O3-ZrO2-SiC whisker were fabricated by hot pressing at 1$700^{\circ}C$, 15MPa and Al2O3-ZrO2 by pressureless sintering at 1$600^{\circ}C$. A controlled flaw/strength technique was utilized to determine fracture resistance as a function of crack extension and R-curve behaviour was determined from the relationship which is KR=K0(Δa)m. R-curveresults were KR=6.173$\times$Δa0.031 for Al2O3-ZrO2, KR=18.796$\times$Δa0.172 for Al2O3-SiC whisker and KR=11.96$\times$Δa0.110 for Al2O3-ZrO2-SiC whisker composite. From the analysis of R-curve and expeirmental data above three composites, it is found that R-curve behaviour of Al2O3-ZrO2-SiC whisker composite was dominated initially by the strengthening effect of ZrO2 and after, some extended crack were influenced by the effect of SiC whisker. Analysis of SEM and X-ray data revealed that whisker bridging in the crack wake and whisker pull-out mechanisms were the main mechanism for the R-curve behaviour.
김현하(Hyun Ha Kim),김대현(Dae Hyun Kim),권다남(Da Nam Kwon) 한국평생교육학회 2024 평생교육학연구 Vol.30 No.1
이 연구는 학교-지역 연계 교육 관련 연구 동향을 파악하고, 이를 통해 학교-지역 연계 교육의 현황 및 향후 발전 방향을 모색하는 데 그 목적이 있다. 이를 위해 KCI 등재 이상의 학술지에 2003년부터 2023년까지 발행된 362개 논문을 선정하여 텍스트마이닝, 의미 연결망 분석, CONCOR 분석을 통해 연구 동향을 분석하였다. 그 결과, 2013년을 기점으로 발행 논문의 수가 증가하는 경향을 보였고, 전체 의미 연결망에서 학교 지역 연계, 문화예술, 학교, 사례연구, 마을교육공동체, 교육과정, 대학, 연계, 사회과, 초등이 중요한 키워드로 나타났다. 그리고 N-gram 분석 결과 키워드 빈도 및 TF-IDF의 상위 키워드가 학교-지역 연계 교육과 동시에 빈번하게 출현하였다. 마지막으로, CONCOR 분석을 통해 문화예술교육, 교육과정 운영 사례, 학교와 지역의 연계 방법, 지역교육공동체, 학교-지역 연계 교육과정의 개발, 교육 프로그램, 학교급별 학교-지역 연계 교육의 발전 방향 등 총 8개의 군집을 확인하였다. 이를 통해 학교-지역 연계 교육 발전 및 이를 위해 요구되는 연구에 대한 논의를 하였다. The purpose of this study is to identify research trends related to school-region linked education and to explore the current status and future development direction of this education. To achieve this, 362 papers published from 2003 to 2023 in KCI-registered journals were selected and the research trends were analyzed using text mining, semantic network analysis, and CONCOR analysis. The results revealed that the number of published papers has tended to increase since 2013. Moreover, in the overall semantic network, school-area connection, culture and arts, schools, case studies, village education community, curriculum, universities, connection, social studies, and elementary school are importan, appearing as a keywords. In addition, the results of an N-gram analysis, keyword frequency assessment, and the identification of top keywords using TF-IDF found that certain terms frequently appeared in conjunction with school-region linked education. Lastly, through a CONCOR analysis, a total of eight clusters were identified. Discussions were then held on the development of school-region linked education and the research required for this.
T0901317 as an Inhibitor of Transcriptional Activation of Constitutive Androstane Receptor (CAR)
Hyun-Ha Kim(김현하),Wongi Seol(설원기) 한국생명과학회 2011 생명과학회지 Vol.21 No.4
T0901317은 핵수용체 전사인자인 liver X receptor (LXR, NR1H2/3)의 강력한 합성 리간드이다. 그러나, T0901317은 farnesoid X receptor (FXR, NR1H4)와 pregnane X receptor (PXR, NR1I2)에 대해 작용물질(agonist)로, androgen receptor (AR, NR3C4)와 rertinoid-related orphan receptor-α (ROR-α, NR1F1)에 대해 길항제(antagonist)로 작용하여, LXR외에 적어도 다른 4종의 핵수용체에 대해 그 활성을 조절한다고 보고되었다. 우리는 T0901317이 또 다른 핵수용체인 constitutive androstane receptor (CAR, NR1I3)에 대해 저해제로 기능함을 확인하였다. CAR는 이미 T0901317에 의해 기능이 조절된다고 알려진 PXR, FXR, LXR과 더불어 간에서 생체이물과 콜레스테롤의 대사작용에 중요한 역할을 하므로 T0901317에 의해 CAR의 활성이 조절된다는 사실은, 간세포에서 T0901317을 이용한 실험결과를 해석할 때 세포 내에 이미 존재하는 이들 핵수용체 단백질의 영향을 고려하여 주의깊게 해석해야 함을 의미한다. T0901317 is a potent synthetic ligand for liver X receptor (LXR, NR1H2/3), a member of the nuclear receptor superfamily that functions as a transcription factor. However, T0901317 has been also reported to modulate the activity at least four other nuclear receptors (NRs), acting as agonists for farnesoid X receptor (FXR, NR1H4) and pregnane X receptor (PXR, NR1I2) and as antagonists for androgen receptor (AR, NR3C4) and retinoid-related orphan receptor-α (ROR-α, NR1F1). We report here that T0901317 can also function as an inhibitor for constitutive androstane receptor (CAR, NR1I3). Since CAR is a major player of xenobiotic and cholesterol metabolism in the liver, along with PXR, FXR and LXR, which are reported to be regulated by T0901317, this further complicates the interpretation of potential results with T0901317 in liver cells.
우리나라 일부 영아의 혈액 셀레늄과 Glutathione Peroxidase 효소 활성에 관한 연구
김현하 (Kim,Hyun-Ha ),양혜란 (Yang,Hye-Ran),김혜영 (Kim,Hye-Young ) 韓國營養學會 2011 Journal of Nutrition and Health Vol.44 No.2
We investigated the selenium (Se) nutrition status in Korean infants. The mean serum Se concentration in infants was 66.9 μg/L, and it increased with increasing in infant age: 57.6 μg/L at 0-5 months, 71.8 μg/L at 6-11 months, and 75.5 μg/L at 12-24 months. Serum glutathione peroxidase (GPx) activity also increased with infant age. Serum Se concentration in infants was positively correlated with serum GPx activity (r = 0.565, p < 0.01). At 0-5 months, human milk-fed infants tended to have higher Se concentrations and GPx activity than those of formula-fed infants, but the result was not significant. With the introduction of supplemental feeding at 6-24 months of age, serum Se concentration was not different between the groups. Therefore, human milk feeding seemed to be more appropriate for infant Se nutrition than infant formula feeding during the first 6 months of life, but supplemental feeding became more important later to maintain good Se nutrition status. (Korean J Nutr 2011; 44(2): 112 ~ 118)
김현하,김혜영 용인대학교 자연과학연구소 2009 自然科學硏究所論文誌 Vol.14 No.1
A study was designed to assess the current status of infant supplemental feeding through a survey at Bundang area. In case of time for starting the baby food, infant age at 7∼9 months accounted for the most. The 90% of the parents were making their own baby food at home. Food products which were used to make baby food were thin rice gruel, sweet potato, rice gruel, potato, soft-boiled rice, and noodle from grain group, and beef, chicken, tofu, fish with white meat, egg yolk, egg white, fish with red meat and pork from meat group in the order named. In vegetable group, broccoli, carrot, sweet pumpkin, spinach, mushroom and bean were used, and in case of dairy products, cheese, milk, drinking yogurt, and plain yogurt were commonly used. In case of baby food from store, drinking products, powdered products, bottled products and retort pouch were used. The most popular first baby food was thin rice gruel in many cases.