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Hwang, Jiseon,Kim, Kyung Mi,Chae, Junghyun,Chang, Jinho Pergamon Press 2018 Electrochimica acta Vol.291 No.-
<P><B>Abstract</B></P> <P>In this article, we report that electrochemically generated quaternary ammonium polybromide (QBr<SUB>2n+1</SUB>) droplets can act not only as electrochemical reactors for the electro-oxidation of Br<SUP>−</SUP>, but also as tiny reductants for Br<SUB>2</SUB> dissolved in an aqueous phase. We suggest two different theoretic models: <I>Cloud</I> and <I>Droplet</I>. In the <I>Cloud</I> model, we consider a cloud composed of small droplets located in the vicinity of a Pt ultramicroelectrode (UME). The positive feedback loop of the redox reaction is derived in the gap between the <I>Cloud</I> and the Pt UME, which leads to catalytic current enhancement, like the positive feedback mode of scanning electrochemical microscopy (SECM). In the <I>Droplet</I> model, a droplet adsorbed on the center of a Pt UME drives the catalytic feedback loop of the redox reaction. Next, we adopted the two theoretical models to explain the current amplification by QBr<SUB>2n+1</SUB> observed in our experimental systems. In the early potential region for electro-oxidation of Br<SUP>−</SUP>, we found the QBr<SUB>2n+1</SUB> droplets-<I>Cloud</I> model was a more reliable scenario for the catalytic current amplification. As the potential became more positively biased, stochastic collisions of QBr<SUB>2n+1</SUB> droplets occurred on the Pt UME, and in this stage, we determined that the QBr<SUB>2n+1</SUB>-<I>Droplet</I> model was the main catalytic mechanism for Br<SUP>−</SUP> electro-oxidation in the presence of QBr in the solution.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Hwang, Jiseon,Chang, Jinho The Electrochemical Society 2018 Journal of the Electrochemical Society Vol.165 No.7
<P>In this article, we account for the reduction pathway of quaternary ammonium polybromide (QBr(2n +/- 1)) droplets on Pt ultramicroelectrode (UME). In previous work, we electrochemically analyzed stochastic current spikes from Br -electrolysis in QBr(2n +/- 1) droplets by their particle impact on Pt UME. For electro-reduction of QBr 2n +/- 1 droplets through chronoamperometry, we found no evidence of stochastic current spikes, which are supposed to be evidence for direct electro-reduction (DR) of QBr(2n +/- 1) droplets to Br- and Q(+) through their particle impact on Pt UME. Instead, we suggest an indirect electro-reduction (IDR) mechanism for QBr(3) droplets via the following pathway based on a finite element analysis. The electrochemically generated QBr(3) droplets are mostly distributed in the vicinity of Pt UME within our experimental time scale due to their sizes. QBr(3) equilibrated with Q(+) and Bra(-) and the liberated Br3(-) from QBr(3) droplets are electrochemically reduced to Br until all the QBr(3) droplets in the vicinity of the Pt UME are depleted. We further found that QBr(2n +/- 1) species (n = 2 and 3) are not electro-reduced through IDR but are precipitated on Pt UME. In the chronoamperogram at each forward step of the fifty potential cycles, CA(forward-50 cycles), the potential was applied for 0.4 s where Br is oxidized on the Pt UME in an acidic solution containing QBr. In the CA(forward-50 cycles), the current spikes attributed to Br- -electrolysis in QBr(2n +/- 1) droplets by their particle-impact on Pt UME were observed. In the CA(reverse-50 cycles), the potential was applied for another 0.4 s, which is enough to drive the electro-reduction of Br3(-) on Pt UME. The frequency of the current spikes in the CA(forward-50 cycles) significantly declined as the potential-cycles increased. The chronoamperometric analyses indicated that the Pt surface is partially blocked by the reduction-inactive QBr(2n +/- 1 )species, which was confirmed to be mostly QBr(5) and QBr(7) by Raman spectroscopy. (C) 2018 The Electrochemical Society.</P>
음악-과학 GI-융합교육 프로그램이 중학교 과학영재의 창의성에 미치는 효과
황지선(Hwang, Jiseon),정종우(Jung, Jongwoo) 한국창의력교육학회 2021 창의력교육연구 Vol.21 No.4
본 연구는 중학교 과학영재들에게 음악-과학 GI-융합교육 프로그램을 실행하여 창의성에 미치는 효과를 알아보았다. 대전의 A, B, C, D 중학교에서 모인 지역공동 중학교 2학년 과학 영재학생에게 총 12차시의 프로그램을 적용하였고, 창의적 사고와 창의적 인성 검사를 사전-사후 실시하였다. 또한, 수업 영상 녹화, 모둠별 활동 음원 녹음, 수업이 끝난 이후에 2명씩 15분 동안 진행한 총 6명의 인터뷰 음원 녹음, 활동지 등을 토대로 질적 연구를 시행하였다. 양적 연구 결과, 창의적 사고와 창의적 인성 점수가 통계적으로 유의미한 결과를 나타내었고, 창의적 사고의 하위요소인 유창성, 독창성, 성급한 종결에 대한 저항에서 통계적으로 유의미하게 향상되었다. 또한, 창의적 인성의 하위요소인 인내와 열정, 자신감, 모험과 도전, 호기심, 개방과 자율에서 통계적으로 유의미한 결과를 보였다. 질적 연구 결과, 창의적 문제해결력, 생각의 공유를 통한 시너지 효과, 이를 통한 사고의 확장 및 유창성, 독창성, 정교성이 나타났으며, 이러한 내용을 토대로 창의적 사고가 발현되고 있음을 알 수 있었다. 그리고, 수업을 경험하며 자신감의 향상 및 내적 동기의 생성, 인내와 열정, 상상, 모험과 도전, 개방과 자율과 같은 창의적 인성이 나타나고 있었다. 이러한 결과는 음악-과학 GI-융합교육 프로그램이 창의적 사고와 창의적 인성 향상에 효과적이며 창의성의 발현으로 나타남을 시사한다. This study examined the effects of music-science GI-convergence education program on creativity of science gifted students in middle school. A total of 12 sessions of the program were provided to the second graders of A, B, C, and D middle school in Daejeon, and pre- and post-creative thinking and creative personality tests were conducted. Moreover, class video recording, group activity recording, 15-minute 2-person interview recording of 6 students after class, and activity sheets were qualitatively analyzed. As a result of quantitative analysis, creative thinking and creative personality scores were statistically significant, and the sub-factors of creative thinking, fluency, originality, and resistance to hasty termination, were statistically significantly improved. In addition, perseverance and passion, confidence, adventure and challenge, curiosity, openness and autonomy, which were sub-elements of creative personality, were statistically significant. As a result of qualitative analysis, creative problem-solving ability, synergy effect through sharing of thoughts, expansion of thinking and fluency, originality, and sophistication were revealed, and creative thinking based on these contents was expressed. Furthermore, through the class experience, creative personality such as improvement of self-confidence and generation of intrinsic motivation, patience and passion, imagination, adventure and challenge, and openness and autonomy appeared. These results suggest that the music-science GI-convergence education program is effective in improving creative thinking and creative personality and leads to the expression of creativity.
동시진공증착법으로 형성한 (Ag<SUB>w</SUB>Cu<SUB>1-w</SUB>)(In<SUB>x</SUB>Ga<SUB>1-x</SUB>)Se₂ 박막 태양전지의 Ag 첨가 효과
황지선(Jiseon Hwang),조윤애(Yunae Cho),윤재호(Jae Ho Yun),어영주(Young-Joo Eo),곽지혜(Jihye Gwak),조아라(Ara Cho),박주형(Joo Hyung Park),안세진(Se Jin Ahn),유진수(Jin So Yoo),안승규(Seung Kyu Ahn),조준식(Jun Sik Cho),김기환(Kihwan Kim) 한국태양에너지학회 2020 한국태양에너지학회 학술대회논문집 Vol.2020 No.10
열처리 조건이 시금치의 이화학적 특성 및 영양 조성에 미치는 효과
이지선, 황인국, 유선미, 민상기, 김광일, 조연지, 최미정 忠北大學校 農業科學硏究所 2015 農業科學硏究 Vol.31 No.1
This study investigated the effect of thermal treatment (blanching) conditions on the physicochemical and nutritional properties of spinach. For thermal treatments, fresh spinach was treated by three blanching methods including boiled water, steam and pan frying treatments. At the varying time intervals of treatments, pH, color, shear force, proximate composition, organic acid content, peroxidase activity and microbial counts were evaluated. The pH of all treatments tended to increase with increasing blanching time, however, no significant differences among treatments were obtained. The shear force of spinach decreased with blanching time, particularly hot water treatment showed the rapid decrease in the shear force of spinach. The lightness of spinach showed similar pattern with shear force. For proximate compositions, the highest moisture content was found in hot water treatment, while crude protein and ash were highest in steam treatment. Due to the usage oil, pan frying treatment involved in the highest lipid content. The organic acid content treatment was in the order of hot water, pan frying and steam treatment. The thermal treatments attributed to low total plate count of spinach. In addition, thermophilic bacteria, coliform, mold and yeast were not detected in all thermal treatments. Peroxidase activity was lowered by applied thermal treatments. Based on the results, the best blanching condition for spinach was found in steam treatment for 60 s where the spinach showed the minimal changes in physicochemical and nutritional properties of spinach.