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구리염 수용액에서 알루미늄의 이상 반응 거동을 소재로 한 탐구학습 자료 개발
강성원 ( Seongwon Kang ),권은주 ( Eunju Kwon ),노영주 ( Youngju Noh ),배중연 ( Joongyeon Bae ),심보경 ( Bokyoung Shim ) 한국현장과학교육학회 2018 현장과학교육 Vol.12 No.4
표준환원전위 차이에 의하면 수용액 속에서 구리 이온과 금속 알루미늄은 자발적인 산화-환원 반응을 일으킨다. 그런데 실험에서 반응을 관찰하면 알루미늄은 질산 구리, 황산 구리 수용액에서 반응하지 않고 염화 구리 수용액에서만 반응한다. 두 가지 수용액에서 반응이 일어나지 않는 것은 알루미늄의 산화피막이 보호막으로 작용한 때문이고, 염화 구리 수용액에서 반응하는 것은 염화 이온에 의한 공식(pitting corrosion) 현상으로 산화피막이 제거되기 때문이다. 반면 아연은 질산 구리, 황산 구리, 염화 구리 수용액 속에서 모두 반응한다. 본 교육 자료는 알루미늄이 서로 다른 구리염 수용액에서 선별적으로 반응하는 원인을 학생들이 직접 고등학교 수준의 화학 지식과 준비물만으로 가설을 설정하고 간단한 실험으로 증명까지 할 수 있음을 보이고, 학생들에게 적용할 수 있는 탐구활동 학습 자료를 제공한다. 이 활동을 통해 학생들이 과학의 핵심인 실험적 증명 과정을 즐겁게 체험할 수 있을 것으로 기대한다.
Cha, Seongwon,Choi, Chan-Bum,Han, Tae-Un,Kang, Changsoo Paul,Kang, Changwon,Bae, Sang-Cheol Wiley Subscription Services, Inc., A Wiley Company 2007 Vol.56 No.5
<B>Objective</B><P>Anti–cyclic citrullinated peptide (anti-CCP) antibodies are rheumatoid arthritis (RA)–specific serologic markers. RA susceptibility has been associated with HLA–DRB1 shared epitope (SE) alleles and single-nucleotide polymorphism (SNP) haplotypes in the peptidyl arginine deiminase 4 gene (PADI4). This study was undertaken to determine whether anti-CCP levels are associated with PADI4 haplotypes and/or SE alleles in Korean patients with RA.</P><B>Methods</B><P>Three nonsynonymous SNPs in PADI4 (padi4_89, padi4_90, and padi4_92) and SE alleles were genotyped, and serum anti-CCP levels were measured, in 311 patients with nonerosive or erosive RA. The relationships between anti-CCP levels and PADI4 haplotypes and/or SE alleles were analyzed statistically.</P><B>Results</B><P>Anti-CCP levels were significantly higher in patients carrying the PADI4 RA risk haplotype than in patients who did not have the risk haplotype, among anti-CCP–positive patients with RA with a disease duration of ≤34 months (P = 0.041), but not among patients with a longer disease duration or among those who had erosive RA versus nonerosive RA. In contrast, the levels were significantly higher in SE carriers than in noncarriers among patients with RA with a disease duration of ≥141 months (P = 0.0037) and among those who had erosive RA (P = 0.000098), but not among patients who had a shorter disease duration or those who had nonerosive RA.</P><B>Conclusion</B><P>The PADI4 RA risk haplotype is associated with increased anti-CCP levels in RA patients with disease of short duration, and PADI4 may play a role in early RA. In contrast, SE alleles are associated with increased anti-CCP levels in RA patients with very longstanding disease and in patients with erosive RA, suggesting that SE alleles play a role in very late RA.</P>
Reinforced Concrete One-Way Slabs with Large Steps
Kang, Thomas H.-K.,Kim, Sanghee,Hong, Seongwon,Hong, Geon-Ho,Park, Hong-Gun American Concrete Institute 2017 ACI structural journal Vol.114 No.4
<P>To evaluate the performance of relatively large steps in reinforced concrete one-way slabs in terms of the flexural behavior of the stepped slabs, a total of 12 specimens with various shapes of steps and different reinforcing details in steps were tested. The primary purpose of this research is to investigate the structural behavior of one-way slabs with steps and to evaluate the performance of steps in slab depending on various details. In comparing the conventional one-way slab with the stepped slab, it was found that: 1) the specimen without supplementary reinforcement in the step showed a very low moment strength and significant damage; 2) the specimens with diagonal reinforcement in the step exhibited substantial early cracks, experienced hinging of the step, and demonstrated a substantial loss of moment strength; and 3) the specimens with a combination of U-bars, inverted U-bars, L-bars, and inverted L-bars performed very well, reaching almost 100% of moment strength of the one-way slab. The U-bars and inverted U-bars were effective in controlling the diagonal cracks, while the L-bars and inverted L-bars were effective in preventing yielding of the slab reinforcement near the step. Based on the crack pattern and the analysis of the structural performance, the design guidelines of reinforcement details of stepped slabs were proposed.</P>