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47 results on '"Kim, Seohee"'

1. Growth of delafossite CuAlO2 single crystals in a reactive crucible

Author

Kim, Du hyung, Kong, Minsik, Kang, Myeongjun, Kim, Minjae, Kim, Seohee, Kim, Youngwook, Yoon, Sangmoon, and Ok, Jong Mok

Subjects
Condensed Matter - Materials Science
Abstract

Delafossite oxide CuAlO2 has engaged great attention as a promising p-type conducting oxide. In this work, high-quality CuAlO2 single crystals with a size of several millimeters (mm) are successfully achieved with a reactive crucible melting method. The crystals are characterized by X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, transport measurement, and magnetic susceptibility measurement. The grown single crystals are free of contamination from a copper oxide flux. This work provides a new approach to growing high-quality delafossite oxide CuAlO2 with a few mm size.

Published
2022
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7. Toward Air-Stable Multilayer Phosphorene Thin-Films and Transistors

Author

Kim, Joon-Seok, Liu, Yingnan, Zhu, Weinan, Kim, Seohee, Wu, Di, Tao, Li, Dodabalapur, Ananth, Lai, Keji, and Akinwande, Deji

Subjects
Condensed Matter - Materials Science
Abstract

Few-layer black phosphorus (BP), also known as phosphorene, is poised to be the most attractive graphene analogue owing to its high mobility approaching that of graphene, and its thickness- tunable band gap that can be as large as that of molybdenum disulfide. In essence, phosphorene represents the much sought after high-mobility, large direct band gap two-dimensional layered crystal that is ideal for optoelectronics and flexible devices. However, its instability in air is of paramount concern for practical applications. Here, we demonstrate air-stable BP devices with dielectric and hydrophobic encapsulation. Microscopy, spectroscopy, and transport techniques were employed to elucidate the aging mechanism, which can initiate from the BP surface for bare samples, or edges for samples with thin dielectric coating highlighting the ineffectiveness of conventional scaled dielectrics. Our pioneering months-long studies indicate that a double layer of Al2O3 and hydrophobic fluoropolymer affords BP devices and transistors with indefinite air-stability for the first time, overcoming a critical material challenge for applied research and development., Comment: 22 pages, 4 figures

Published
2014
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15. Sleep time and duration are associated with periodontitis in a representative sample of Koreans.

Author

Han, Dong‐Hun, Kim, Mi‐Sun, Kim, Seohee, Yoo, Ji‐Won, Shen, Jay J., Han, Dong-Hun, Kim, Mi-Sun, and Yoo, Ji-Won

Abstract

Background: So far, studies on the association between sleep and periodontitis have shown conflicting results. This study assessed the association among sleep duration, sleep time, and periodontitis among a nationally representative Korean population and the mediation effect of WBC.Methods: We analyzed data from the Seventh Korean National Health and Nutrition Examination Survey (KNHANES VII) collected from 2016 to 2018. With the screenings by age (45 to 64), edentate, and the adequacy of information provided, the analysis was confined to a selected group of respondents of 4407 with measurements for the sleep survey and periodontal health status out of total 24,269. Periodontitis was defined according to the World Health Organization's community periodontal index (CPI) code greater than or equal to three, and severe periodontitis was defined as CPI code 4. Multivariable logistic regression analysis was used to test the association between sleep and periodontitis controlling the confounding factors.Results: Those who went to bed during the daytime were associated with periodontitis (OR = 1.49, 95% confidence interval [CI]: 1.07 to 2.07). In a combined sleep time and duration model, those who went to bed at night with a sleep duration of 9 hours or more were associated with periodontitis (OR = 1.69, 95% CI: 1.04 to 2.77) and severe periodontitis (OR = 1.88, 95% CI: 1.02-3.45). WBC count had the highest impact on the association between sleep time and periodontitis.Conclusions: Our findings suggest that an extra-long sleep duration and going to bed during the daytime are associated with periodontitis. [ABSTRACT FROM AUTHOR]

Published
2022
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16. A Novel and Potent EZH1/2 Dual Inhibitor HM97594 for the Treatment of Hematological Malignancies

Author

Jung, Seung Hyun, primary, Hong, DongJin, additional, Kim, SeoHee, additional, Hwang, Jiyoung, additional, Byun, Jooyun, additional, Lee, Miyoung, additional, Koo, Kyounghwa, additional, Lee, Gunwoo, additional, Song, TaeHun, additional, Lim, SunYoung, additional, Kim, Yu-Yon, additional, Park, Hyunjin, additional, Bak, Yesol, additional, Ko, Myoungsil, additional, Jung, Sunyoung, additional, Han, Yuri, additional, Ahn, YoungGil, additional, Kim, YoungHoon, additional, and Suh, KweeHyun, additional

Published
2019
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44. Evaluation of the Catalytic Effect of the Ozone/Carbon Nanotube (O 3 /CNT) Process Using para -Chlorobenzoic Acid ( p CBA).

Author

Yoon, Yeojoon, Moon, Jonghyuk, Kwon, Minhwan, Jung, Youmi, Kim, Seohee, and Kang, Joon-Wun

Subjects
CARBON nanotubes, ALCOHOL, RADICALS (Chemistry), FUNCTIONAL groups, BUTANOL, ACIDS
Abstract

The catalytic effects and mechanisms of the ozone/carbon nanotube (O3/CNT) process usingpara-chlorobenzoic acid (pCBA) were evaluated. To use pCBA as an O3-resistant OH• probe compound in a pure water system at pH 7, an adequate amount of scavenger was needed. During the O3/CNT process, a synergetic catalytic effect by OH• generation on the CNT surface could be evaluated in the condition of excesstert-butyl alcohol (TBA) concentration. The OH• radicals were generated and existed on both the bulk phase and CNT surface. The OH-ct values of the CNT surface and bulk phase in the O3/CNT process for 10 min were 2.1 × 10−5and 2.5 × 10−5μ M·s, respectively. In modifying CNT evaluation, the catalytic effects were the most apparent in the following order: CNT treated with acid then heat (CNT-T), original untreated CNT (CNT-O), and CNT treated with an acid (CNT-A). [ABSTRACT FROM AUTHOR]

Published
2014
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46. Facile and Efficient Method for the Debromination of vic -Dibromides to Alkenes with BiCl 3 /Ga System.

Author

Yoo, ByungWoo, Kim, SeoHee, and Park, YoungKwang

Subjects
*CHEMICAL synthesis, *DEBROMINATION, *BROMIDES, *ALKENES, *BISMUTH compounds, *GALLIUM, *FUNCTIONAL groups
Abstract

BiCl3/Ga was found to be a mild, efficient, and chemoselective system for the debromination of a series of functionally and structurally various vic-dibromides. A broad range of functional groups (ester, carboxy, aldehyde, methoxy, chloro, and ketone) was tolerated under the reaction conditions and only trans olefins were obtained in good yields. [ABSTRACT FROM AUTHOR]

Published
2012
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47. Polarization and charge transport in polymer and 2-D material based field-effect transistors

Author

Kim, Seohee

Subjects
Polymer, Graphene, Field-effect transistor, Charge transport, Polarization
Abstract

This work investigates new semiconductors that are currently being considered for use in flexible electronics. It is critical to understand charge transport physics in field-effect transistors (FETs) to get better device performance and integrate them into commercial products. The charge transport studies include understanding of effect of wide-range of applying voltage (sub-threshold and above threshold operation), dominant charge transport mechanisms under specific conditions (band, band-like and hopping transport), and of polarization effect (polaronic and non-polaronic transport). Charge transport in high-mobility diketopyrrolopyrrole (DPP) co-polymers FETs is investigated. Sub-threshold regime conduction, including diffusion- and drift-limited regimes, are accurately modeled with above threshold regime. Based on modeling results, the realistic density of states (DOS) curve of polymer FETs in a wide range of gate voltages is calculated. From modeled sub- and above- threshold regime mobility data, dominant charge transport mechanisms under specific conditions are investigated. Shallow states charge transport is well-described by multiple trap and release (MTR) transport, while hopping transport models such as variable range hopping (VRH) or Gaussian disorder based model (GDM) can describe deep states charge transport. The transition between the conduction regimes is a function of temperature and carrier density. In addition, a polarization effect from polar molecules in both atmosphere and dielectric on the electronic properties of polymer FETs is demonstrated. High-k and low-k surface dielectric devices are measured in polar and non-polar atmospheres. Dipoles in both conditions affect conduction in polymer FETs, but have different aspects, such as uniformly shifted DOS or only shallow states shifted DOS. The improved electrical characteristics of graphene monolayer sheet FETs with fluoropolymer capping is explained via measurements under polar vapor flow, which is reversible and non-destructive. It is found that the higher dipole moment of polar molecules corresponds to better improvement of electrical properties of graphene FETs, including the Dirac voltage shift, mobility and residual carrier concentration. In addition, a similar experiment is applied to graphene nano-ribbon (GNR) FETs. GNR FETs, which have high on/off ratio but some degraded electrical characteristics due to a considerable number of edge defects, also show a highly improved performance under polar vapor.

Published
2016

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