Jung Hoon Kim

The evaporation of water droplets on polymer surfaces was investigated by using a digital image analysis technique. There were three distinct stages in the water evaporation process: a constant contact area mode, a constant contact angle mode, and a mixed mode that is independent of both the initial quantity of water droplets and the hydrophobic properties of the polymer surfaces. The physical factors influencing the first and second transitions in the evaporation process were found to be the at

The flow dynamics inside evaporating water droplets containing a polymer solute were investigated at various substrate temperatures. A new experimental method (laser absorbance monitoring system) was established to estimate the flow dynamics by measuring the central concentration of the solute in the evaporating droplet. The system showed that the polymer transports inside the evaporating droplets near the end of evaporation changed direction depending on the substrate temperature. The resulting

This paper develops a new discretization method with piecewise linear approximation for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{1}$</tex-math></inline-formula> optimal controller synthesis problem of sampled-data systems, which is the problem of minimizing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_

This study presents an IoT-based construction worker physiological data monitoring platform using an off-the-shelf wearable smart band. The developed platform is designed for construction workers performing under high temperatures, and the platform is composed of two parts: an overall heat assessment (OHS) and a personal management system (PMS). OHS manages the breaktimes for groups of workers based using a thermal comfort index (TCI), as provided by the Korea Meteorological Administration (KMA)

Abstract Reported herein is a copper‐catalyzed S N 2′‐selective allylic substitution reaction using readily accessible allylic chlorides and 1,1‐diborylalkanes, a reaction which proceeds with chemoselective C−B bond activation of the 1,1‐diborylalkanes. In the presence of a catalytic amount of [Cu(IMes)Cl] [IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazole‐2‐ylidene] and LiO t Bu as a base, a range of primary and secondary allylic chlorides undergo the S N 2′‐selective allylic substitution reaction t

This paper is concerned with the delay-dependent stability for the linear systems with a time-varying delay. To get a result in the form of LMI from a Lyapunov–Krasovskii functional, an integral inequality is necessary and Jensen inequality has been a most powerful inequality in the last few years. Recently, based on Wirtinger inequality, an improved integral inequality, encompassing Jensen inequality, was proposed and its application to the stability showed a quite improvement. In this paper, w

Journaling techniques are widely used to guarantee file system consistency of battery-powered mobile devices such as smartphones and tablets. In a journaling file system, system recovery is facilitated by first writing updated data blocks to a journal area and then periodically writing them to their home locations. However, these duplicated writes degrade the performance and shorten the lifetime of NAND flash storage in mobile devices. In particular, a lightweight database library, which is main

In this study, we present a novel method of detecting hard hat use on construction sites using a modified version of an off-the-shelf wearable device. The data-transmitting node of the device contained two sensors, a photoplethysmogram (PPG) and accelerometers (Acc), along with two modules, a global positioning system (GPS) and a low-power wide-area (LoRa) network module. All the components were embedded into a microcontroller unit (MCU) in addition to the power supply. The receiving node includ

The direct introduction of methyl groups into electron-deficient <i>N</i>-heteroarenes has recently emerged as an efficient and promising strategy to afford methylated <i>N</i>-heteroarenes, which are important motifs in a variety of pharmaceuticals and biologically active molecules. Herein, three general state-of-the-art approaches including radical-mediated, transition-metal-catalyzed, or transition-metal-free direct C–H methylations of electron-deficient <i>N</i>-heteroarenes are highlighted.

This study deals with the L 1 analysis of stable finite‐dimensional linear time‐invariant (LTI) systems, by which the authors mean the computation of the L ∞ ‐induced norm of these systems. To compute this norm, they need to integrate the absolute value of the impulse response of the given system, which corresponds to the kernel function in the convolution formula for the input/output relation. However, it is very difficult to compute this integral exactly or even approximately with an explicit

The aim of this paper is to construct a theoretical framework for stability analysis relevant to standing balance of humanoids on top of the linear inverted pendulum model, in which their dynamics between the center of mass (CoM) and the zero moment point (ZMP) is dealt with. Based on the well-known sufficient condition that the contact between the ground and the support leg is stable if the corresponding ZMP is always inside the supporting region, this paper aims at characterizing three types o

3.5 nm sized Pt nanocatalysts supported on silicon oxide nanowires (SiO(X)NWs) were fabricated by decorating the SiO(X)NWs with Pt nanoparticles using a simple physical deposition system without any surface pretreatment. High curvature of the nanowire surface together with the weak metal-substrate interaction helped to maintain discrete particle morphology with spherical shapes during deposition. Catalytic efficiency of the SiO(X)NWs coated with Pt nanoparticles was demonstrated through reductio