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Growth of Highly Single Crystalline IrO<sub>2</sub> Nanowires and Their Electrochemical Applications
Lee, Yumin,Kang, Minkyung,Shim, Jun Ho,Lee, Nam-Suk,Baik, Jeong Min,Lee, Youngmi,Lee, Chongmok,Kim, Myung Hwa American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.34
<P>We present the facile growth of highly single crystalline iridium dioxide (IrO<SUB>2</SUB>) nanowires on SiO<SUB>2</SUB>/Si and Au substrates via a simple vapor phase transport process under atmospheric pressure without any catalyst. Particularly, high-density needle-like IrO<SUB>2</SUB> nanowires were readily obtained on a single Au microwire, suggesting that the melted surface layer of Au might effectively enhance the nucleation of gaseous IrO<SUB>3</SUB> precursors at the growth temperature. In addition, all the electrochemical observations of the directly grown IrO<SUB>2</SUB> nanowires on a single Au microwire support favorable electron-transfer kinetics of [Fe(CN<SUB>6</SUB>)]<SUP>4–/3–</SUP> as well as Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP> at the highly oriented crystalline IrO<SUB>2</SUB> nanowire surface. Furthermore, stable pH response is shown, revealing potential for use as a miniaturized pH sensor, confirmed by the calibration curve exhibiting super-Nernstian behavior with a slope of 71.6 mV pH<SUP>–1</SUP>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-34/jp306900m/production/images/medium/jp-2012-06900m_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp306900m'>ACS Electronic Supporting Info</A></P>
Kang, Minkyung,Lee, Yumin,Jung, Hayoung,Shim, Jun Ho,Lee, Nam-Suk,Baik, Jeong Min,Lee, Sang Cheol,Lee, Chongmok,Lee, Youngmi,Kim, Myung Hwa American Chemical Society 2012 ANALYTICAL CHEMISTRY - Vol.84 No.21
<P>We demonstrate highly efficient electocatalytic activities of single crystalline RuO<SUB>2</SUB> nanorods grown on carbon fiber (CF), i.e., RuO<SUB>2</SUB> nanorod-CF hybrid microelectrode, prepared by a simple thermal annealing process from the Ru(OH)<SUB>3</SUB> precursor at 300 °C. The general electrochemical activity of a RuO<SUB>2</SUB> nanorod-CF microelectrode represents faster electron transfer for the [Fe(CN)<SUB>6</SUB>]<SUP>3–/4–</SUP> couple than that of the bare CF microelectrode which are confirmed from the cyclic voltammetry (CV) measurement. Also, the amperometric response for the H<SUB>2</SUB>O<SUB>2</SUB> oxidation is remarkably facilitated at the RuO<SUB>2</SUB> nanorod-CF microelectrode by not only the enlarged surface area but the high electrocatalytic activity of the RuO<SUB>2</SUB> nanorod material itself. Furthermore, a single microelectrode of RuO<SUB>2</SUB> nanorod-CF exhibits the superior tolerance to Cl<SUP>–</SUP> ion poisoning unlike Pt-based electrocatalysts, indicating the promising sensor candidate in physiological conditions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2012/ancham.2012.84.issue-21/ac302334t/production/images/medium/ac-2012-02334t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac302334t'>ACS Electronic Supporting Info</A></P>
Chun, Sung Hee,Choi, Hyun-A,Kang, Minkyung,Koh, Moonjee,Lee, Nam-Suk,Lee, Sang Cheol,Lee, Minyung,Lee, Youngmi,Lee, Chongmok,Kim, Myung Hwa American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.17
<P>Highly efficient single crystalline ruthenium–vanadium mixed metal oxide (Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB>, 0 ≤ <I>x</I> ≤ 1) nanowires were prepared on a SiO<SUB>2</SUB> substrate and a commercial Au microelectrode for the first time through a vapor-phase transport process by adjusting the mixing ratios of RuO<SUB>2</SUB> and VO<SUB>2</SUB> precursors. Single crystalline Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> nanowires show homogeneous solid-solution characteristics as well as the distinct feature of having remarkably narrow dimensional distributions. The electrochemical observations of a Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> (<I>x</I> = 0.28 and 0.66)-decorated Au microelectrode using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrate favorable charge-transfer kinetics of [Fe(CN)<SUB>6</SUB>]<SUP>3–/4–</SUP> and Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP> couples compared to that of a bare Au microelectrode. The catalytic activity of Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> for oxygen and H<SUB>2</SUB>O<SUB>2</SUB> reduction at neutral pH increases as the fraction of vanadium increases within our experimental conditions, which might be useful in the area of biofuel cells and biosensors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-17/am4016445/production/images/medium/am-2013-016445_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am4016445'>ACS Electronic Supporting Info</A></P>
Evaluation of educational school meal programs in Gyeonggi province, South Korea
Lee, Youngmi,Kim, Oksun,Lee, Uiok,Kwon, Sooyoun 한국영양학회 2017 Journal of Nutrition and Health Vol.50 No.1
Purpose: School meal programs should be part of the educational process to promote good eating habits for students. The purpose of this study was to develop an evaluation scale for educational school meal programs and evaluate the achievement level of educational school meal programs using the developed scale. Methods: The evaluation scale for educational school meal programs consisted of 23 items in eight categories and was developed using content validity ratio (CVR) analysis and analytic hierarchy process (AHP) by 15 related experts. The results of a survey on nutrition teachers or dietitians at 91 elementary, middle, and high schools in Gyeonggi province, South Korea were analyzed to evaluate the achievement levels of educational school meal programs. Results: Overall, total average score was 45.7 out of 100, with significant differences among schools (p = 0.005). Elementary schools (51.9) showed a higher average score than middle (41.5) and high schools (37.1). The score for the category of regular nutrition and dietary education was the lowest (5.7 out of 33.7). In addition, school meal environment (5 out of 10), educational activities through school meal time (9.2 out of 19), and extra-curricular experiential activities (3.5 out of 10) also showed inadequate levels. Conclusion: The results show that the overall level of educational school meal programs is not adequate and needs to be improved, especially at middle and high schools. Government support polices need to be implemented to encourage educational activities related to school meal programs.
Youngmi Lee,Mi-Hyun Kim,Jae Eun Shim,Haeryun Park 한국영양학회 2020 Nutrition Research and Practice Vol.14 No.6
BACKGROUND/OBJECTIVES: This study aimed to improve portion size estimation aids (PSEAs) used in the nutrition survey of the Korea National Health and Nutrition Examination Survey (KNHANES) and validate the accuracy and precision of the newly developed aids. SUBJECTS/METHODS: We conducted intensive interviews with survey experts in KNHANES and consulted with experts to collect opinions about improvement of PSEAs. Based on the results of the interviews, 5 types of PSEAs (rice bowl, earthen pots, mounds, measuring spoons, and thickness sticks) were newly developed using 3-dimensional (3D) modeling or modification of color or shape. Validation tests were conducted with 96 adults 20 years old or older. For the rice bowl and earthen pots, the participants were asked to select the more similar PSEA in size after being shown the real dishes. For the mounds, measuring spoons, and thickness sticks, the participants were presented with actual plates of food and asked to estimate the given portion sizes using the given PSEAs. RESULTS: The improved 2-dimensional (2D) picture aid for the rice bowl reflecting the size distortion by angle of view using 3D modeling was perceived more closely to the actual size than the current 2D picture (P < 0.001). The change of the color of 2D pictures and 3D models, the change of shape of the measuring spoons, and the 3-dimensionalization of the 2D mounds had no significant improvement in the subjects" perception. CONCLUSIONS: The currently used 2D PSEAs need to be fully redesigned using 3D modeling to improve subjects" perception. However, change of color or shape will not be necessary. For amorphous foods, it is suggested that more evaluation be performed before reaching a final conclusion in the use of PSEAs, or alternative ways to improve accuracy of estimation need to be explored.
Monitoring Distributional Changes in Autoregressive Models
Lee, Sangyeol,Lee, Youngmi,Na, Okyoung Taylor Francis 2009 Communications in Statistics Vol.38 No.16
<P> In this artilce, we develop a monitoring procedure for an early detection of distributional changes in autoregressive models. We design the monitoring procedure based on residuals since the test based on the observations is inappropriate. We verify that under regularity conditions, the stopping rule designed to detect changes behaves asymptotically the same as that in iid samples. Simulation results are provided for illustration.</P>