Jung‐Woo Park

A method of collision avoidance is described by using simple geometric approach. Two UAVs are dealt with and considered as point masses with constant velocity. This paper discusses en route aircraft which are assumed to be linked by real time data bases like ADS-B. With this data base, all UAVs share the information each other. Calculating PCA (point of closest approach), we can evaluate the worst conflict condition between two UAVs. This paper proposes one resolution maneuvering logic, which ca

This article describes recent advances that have been made in the development of methods for post-grafting of silica surfaces using functionalized organosilanes. While procedures employing conventional trialkoxysilane precursors have been utilized to immobilize organic and biological molecules onto inorganic supports, such as silica and glass, they have intrinsic limitations including sensitivity to hydrolysis and slow reaction rates. In this context, new synthetic equivalents to conventional tr

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

We report a Rh-catalyzed enantioselective cycloisomerization of α,ω-heptadienes to afford cyclohexenes bearing quaternary carbon centers. Rhodium(I) and a new SDP ligand promote chemoselective formation of a cyclohex-3-enecarbaldehyde motif that is inaccessible by the Diels-Alder cycloaddition. Various α,α-bisallylaldehydes rearrange to generate six-membered rings by a mechanism triggered by aldehyde C-H bond activation. Mechanistic studies suggest a pathway involving regioselective carbometalat

The hydrosilylation of alkynes is a chief chemical method for accessing a range of alkenylsilanes, which can be derivatized to obtain value-added hydrocarbons and utilized in diverse applications. While noble metal-based catalytic procedures have shown great success in accessing vinylsilanes within the context of both academia and industry, replacing the noble metals with cheaper and more abundant base metals has recently drawn significant interest due to their catalytic sustainability and compe

We report herein an Ir-catalyzed intermolecular amino group transfer to β-keto esters (amides) to access α-aminocarbonyl products with excellent chemoselectivity. The key strategy was to engineer electrophilicity of the putative Ir-nitrenoids by tuning electronic property of the κ²-<i>N</i>,<i>O</i> chelating ligands, thus facilitating nucleophilic addition of enol π-bonds of 1,3-dicarbonyl substrates.

A novel and efficient grafting method for covalent bonding of functional organic molecules to silica or glass surfaces has been developed. The protocol employs transition-metal-catalyzed reactions of vinylsilanes with surface hydroxyl groups. Dimethyldivinylsilane can be used in this procedure as a linker in which one vinyl group is used for direct C-C bond formation with a functional organic molecule and the other is employed to immobilize the alkylsilyl group onto the hydroxyl surface of the s

While migratory functionalization of alkynes has been recognized as a unique way to access allylic functionalities via π-allyl metal intermediates, hydrofunctionalization of 2-alkynes to afford α-functional olefins has been unexplored. We describe herein the use of a cobalt hydride based system for regioselective migratory hydrofunctionalization of 2-alkynes to furnish α-vinylsilanes and α-vinylgermanes by a mechanistic understanding of the cobalt hydride species on alkyne π-bond migration. The

This paper describes a method to improve the 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 impl

We describe a protocol for cobalt-catalyzed hydrosilylation of 3-alkynes with accompanying π-bond migration. Mechanistic studies indicate that (i) cobalt(I)-hydride bearing a bulky bisphosphine ligand is the key intermediate and (ii) π-bond migration occurs prior to hydrosilylation. The cascade process selectively furnishes terminal branched allylsilanes under mild conditions.

Highly efficient O-silylation of alcohol with vinylsilane was developed using a catalyst system consisting of [(COE)(2)RhCl](2) and HCl. In this reaction, a key intermediate is chlorosilane, generated from vinylsilane and HCl, which can be regenerated in the catalytic cycle. Various alcohols and vinylsilanes were applied to the preparation of silyl ether compounds with this catalyst system.

A recyclable catalyst for chelation-assisted hydroacylation of an olefin with primary alcohol was developed using hydrogen-bonding self-assembled catalysts consisting of 2,6-diaminopyridine and barbiturate phosphine-rhodium(I) complex. Upon heating, these two catalysts act as homogeneous catalysts due to cleavage of the hydrogen bond, and these associate to form supramolecular assemblies via hydrogen bonding that can be separated from immiscible product phase upon cooling after the reaction.

This paper describes a method to improve the control characteristics of an interior permanent magnet synchronous motor for an electric vehicle. At the motor for electric vehicle, d- and q-axis inductances are varied to a great extent. So, variation characteristics for d- and q-axis inductance are analyzed as function of current magnitude and also current phase angle. The proposed method makes use of the learning capability of neural networks to implement an adaptive vector control structure. Als

By using Pd⁰ /Mandyphos, we achieved a three-component aminoarylation of alkynes to generate enamines, which are then hydrolyzed to either α-arylphenones or α,α-diarylketones. This Pd-catalyzed method overcomes established known pathways to enable the use of amines as traceless directing groups for C-C bond formation.