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153. Selective SnOx Atomic Layer Deposition Driven by Oxygen Reactants

Author

Mi Yoo, Hyun Mo Lee, Hyun You Kim, Park Jung-Woo, Jung Hoon Lee, Yeonjin Yi, Donghee Kang, Jin-Seong Park, and Wan Ho Choi

Subjects
Ozone, Materials science, chemistry.chemical_element, 02 engineering and technology, Crystal structure, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Oxygen, 0104 chemical sciences, Amorphous solid, Absorbance, chemistry.chemical_compound, Atomic layer deposition, chemistry, Chemical engineering, General Materials Science, Crystallite, Thin film, 0210 nano-technology
Abstract

SnOx thin films were successfully deposited by the thermal atomic layer deposition (ALD) method using N,N′-tert-butyl-1,1-dimethylethylenediamine stannylene(II) as a precursor and ozone and water as reactants. The growth of SnO and SnO2 films could be easily controlled by employing different reactants and utilizing different ozone and water concentrations, respectively. The formation of both SnO and SnO2 films exhibited typical surface-limiting reaction characteristics, although their growth behaviors differ from one another. The combined studies of density functional theory calculations and experimental analyses showed that the difference in growth behavior of the SnO and SnO2 films can be attributed to the stability of ozone and water on the SnO2 and SnO films. SnO and SnO2 films have different crystal structures and both films were crystallized from the amorphous to polycrystalline states following an increase in the deposition temperature. The absorbance and refractive index of the thin films were inv...

Published
2018
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154. A one-step method for covalent bond immobilization of biomolecules on silica operated in aqueous solution† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c8sc02565g

Author

Sim, Yong-Kyun, Jung, Heetae, Kim, Su Hyun, Park, Jung-Woo, Park, Woo-Jin, and Jun, Chul-Ho

Subjects
Chemistry
Abstract

One-step covalent bond immobilization of biomolecules on silica in water is promoted by weak organic acid using bifunctional linker., A simple, one-step method for covalent bond immobilization of biomolecules on silica operated in water is described. In the approach, an NHS-ester linked methallylsilane is utilized as a bifunctional linker to couple the biomolecule to the silica surface. Weak organic acid such as acetic acid activates the silica surface enough to react with bifunctional linker without destroying activity of biomolecule.

Published
2018

166. Improvement of control characteristics of interior permanent-magnet synchronous motor for electric vehicle

Author

Park, Jung-Woo, Koo, Dae-Hyun, Kim, Jong-Moo, and Kim, Heung-Geun

Subjects
Motors -- Research, Electric vehicles -- Design and construction, Vector control -- Testing, Magnets, Permanent -- Usage, Business, Computers, Electronics, Electronics and electrical industries
Abstract

This paper describes a method to improve control characteristics of an interior permanent-magnet synchronous motor for an electric vehicle (EV). At the motor for an electric vehicle, d- and q-axes inductances are varied to a great extent. Therefore, variation characteristics for d- and q-axes inductances are analyzed as a function of both current magnitude and current phase angle. A new vector control algorithm is proposed that makes use of the learning capability of a neural network to implement d- and q-axes inductances to be varied according to current magnitude and also current phase angle. Also, a distribution law of torque reference to improve driving characteristics of the two motor-driven EV is proposed. Advanced performance is verified through numerical method and experiments. Index Terms--Electric vehicle, interior permanent-magnet synchronous motor, neural network, traction control, vector control.

Published
2001

167. Clonal dynamics in early human embryogenesis inferred from somatic mutation

Author

Park, Seongyeol, primary, Mali, Nanda Maya, additional, Kim, Ryul, additional, Choi, Jeong-Woo, additional, Lee, Junehawk, additional, Lim, Joonoh, additional, Park, Jung Min, additional, Park, Jung Woo, additional, Kim, Donghyun, additional, Kim, Taewoo, additional, Yi, Kijong, additional, Choi, June Hyug, additional, Kwon, Seong Gyu, additional, Hong, Joo Hee, additional, Youk, Jeonghwan, additional, An, Yohan, additional, Kim, Su Yeon, additional, Kim, Moonkyu, additional, Kim, Dong Sun, additional, Park, Ji Young, additional, Oh, Ji Won, additional, and Ju, Young Seok, additional

Published
2020
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168. (Invited) Highly Stable Self-Aligned Top-Gate Indium Gallium Zinc Oxide Thin-Film Transistors for High-Resolution OLED TV and Mobile Displays

Author

Kim, Jung Bae, primary, Tsai, Yun-chu (Pipi), additional, Lim, Rodney, additional, Wang, Zhiyuan, additional, Hao, Mei, additional, Wang, Sheng-Wen (Gordon), additional, Park, Jung Woo, additional, Zhao, Lai, additional, Bender, Marcus, additional, Yim, Dong Kil, additional, and Choi, Soo Young, additional

Published
2020
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169. The Contribution of Small Phytoplankton Communities to the Total Dissolved Inorganic Nitrogen Assimilation Rates in the East/Japan Sea: An Experimental Evaluation

Author

Bhavya, Panthalil S., primary, Kang, Jae Joong, additional, Jang, Hyo Keun, additional, Joo, HuiTae, additional, Lee, Jae Hyung, additional, Lee, Jang Han, additional, Park, Jung Woo, additional, Kim, Kwanwoo, additional, Kim, Hyung Chul, additional, and Lee, Sang Heon, additional

Published
2020
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180. Platinum-group element geochemistry of the volcanic rocks associated with the Jaguar and Bentley Cu-Zn volcanogenic massive sulfide (VMS) deposits, Western Australia: implications for the role of chalcophile element fertility on VMS mineralization

Author

Park, Jung-Woo, Campbell, Ian, Park, Jung-Woo, and Campbell, Ian

Abstract

We report whole-rock major, trace, and platinum-group element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and chalcophile element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of chalcophile element fertility on the formation of VMS deposits. The fractionated primitive mantle– normalized trace element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at < 4 ppm Yb, whereas they abruptly decrease at > 4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as chalcophile element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfideundersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enoug

Published
2020

187. Towards a Māori Telepresence System

Author

Park, Jung-Woo Noel, primary, Mills, Steven, additional, Whaanga, Hemi, additional, Mato, Paora, additional, Lindeman, Robert W., additional, and Regenbrecht, Holger, additional

Published
2019
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194. Head-to-Head Homocoupling of Ynamides viaa Dual Activation Mode of Triple Bonds by Half-Sandwich Metal Complexes

Author

Sahoo, Manoj Kumar, Pradhan, Sourav, Kim, Dongwook, Park, Jung-Woo, and Chang, Sukbok

Abstract

Reported herein is the half-sandwich Rh-mediated head-to-head homocoupling of terminal ynamides to furnish dienyl bisamido rhodacyclic complexes, where the Rh–vinyl bond was formed selectively at the α-carbon to the nitrogen atom. This transformation was extended to include piano-stool Ru and Ir complexes to display an analogous homocoupling reactivity. Based on density functional theory studies, the reaction was proposed to proceed viaa dual activation mode of the ynamide triple bonds: (i) generation of a zwitterionic keteniminyl metal species to induce an intramolecular chloride transfer and (ii) syn-carbometallation of the second coordinated alkynes by the alkenyl metal intermediate. An oxidative transformation of the homocoupled metal complexes gave multifunctional dienyl bisamide compounds.

Published
2022
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197. Rh-catalyzed desymmetrization of α-quaternary centers by isomerization-hydroacylation† †Electronic supplementary information (ESI) available: Materials and methods, reaction procedures, characterization data. CCDC 1056687, 1062118. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01553g Click here for additional data file. Click here for additional data file

Author

Park, Jung-Woo, Kou, Kevin G. M., Kim, Daniel K., and Dong, Vy M.

Subjects
Chemistry
Abstract

A Rh-catalyzed desymmetrization of α,α-bis(allyl)aldehydes occurs by enantioselective isomerization followed by olefin-directed hydroacylation., We describe a Rh-catalyzed desymmetrization of all-carbon quaternary centers from α,α-bis(allyl)aldehydes by a cascade featuring isomerization and hydroacylation. This desymmetrization competes with two other novel olefin functionalizations that are triggered by C–H bond activation, including carboacylation and bisacylation. A BIPHEP ligand promotes enantioselective formation of α-vinylcyclopentanones. Mechanistic studies support irreversible and enantioselective olefin-isomerization followed by olefin-hydroacylation.

Published
2015

198. Gold and tin mineralisation in the ultramafic-hosted Cheoeum vent field, Central Indian Ridge.

Author

Choi, Sun Ki, Pak, Sang Joon, Kim, Jonguk, Park, Jung-Woo, and Son, Seung-Kyu

Subjects
SULFIDE minerals, SPHALERITE, MID-ocean ridges, HYDROTHERMAL deposits, TIN, PYRRHOTITE, GEOCHEMISTRY, MINERALOGY
Abstract

The Cheoeum vent field (CVF) is the first example of an inactive ultramafic-hosted seafloor massive sulphide (SMS) deposit identified in the middle part of the Central Indian Ridge. Here, we report on the detailed mineralogy and geochemistry of ultramafic-hosted sulphide sample atop a chimney, together with a few small fragments. Hydrothermal chimneys are characterised by high concentrations of Au (up to 17.8 ppm) and Sn (up to 1720 ppm). The sulphide mineralisation in the CVF shows (1) early precipitation of anhedral sphalerite and pyrite–marcasite aggregates under relatively low-temperature (< 250 °C) fluid conditions; (2) intensive deposition of subhedral pyrrhotite, isocubanite, chalcopyrite, Fe-rich sphalerite (Sp-III), and electrum from high-temperature (250–365 °C) and reduced fluids in the main mineralisation stage; and (3) a seawater alteration stage distinguished by the mineral assemblage of marcasite pseudomorphs, altered isocubanite phase, covellite, amorphous silica, and Fe-oxyhydroxides. Electrum (< 2 μm in size) is the principal form of Au mineralisation and is mainly associated with the main mineralisation stage. The consistently high fineness of electrum (801 to 909‰) is indicative of the selective saturation of Au over Ag in the fluid during high-temperature mineralisation, which differs from the Au mineralisation associated with typical basaltic-hosted hydrothermal systems on mid-ocean ridges. Tin is mainly substituted in structures of sphalerite, isocubanite, and chalcopyrite as a solid solution, and not as mineral inclusions. The continuously ascending hydrothermal fluids enable the early formed Sn-bearing sulphide to be dissolved and reprecipitated, producing significantly Sn-enriched replacement boundaries between isocubanite and Sp-III. This study suggests that Au–Sn mineralisation could be facilitated by the low redox potential of ultramafic-hosted hydrothermal systems such as in the CVF, which may be a common occurrence along slow-spreading mid-ocean ridges. [ABSTRACT FROM AUTHOR]

Published
2021
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