Publications by authors named "Hakyong Kim"

The outbreak of novel COVID-19 disease elicited a wide range of anti-contagion and economic policies like school closure, income support, contact tracing, and so forth, in the mitigation and suppression of the spread of the SARS-CoV-2 virus. However, a systematic evaluation of these policies has not been made. Here, 17 implemented policies from the Oxford COVID-19 Government Response Tracker dataset employed in 90 countries from December 31, 2019, to August 31, 2020, were analyzed.

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The outbreak of the novel COVID-19, declared a global pandemic by WHO, is the most serious public health threat seen in terms of respiratory viruses since the 1918 H1N1 influenza pandemic. It is surprising that the total number of COVID-19 confirmed cases and the number of deaths has varied greatly across countries. Such great variations are caused by age population, health conditions, travel, economy, and environmental factors.

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Since the outbreak of novel SARS-COV-2, each country has implemented diverse policies to mitigate and suppress the spread of the virus. However, no systematic evaluation of these policies in their alleviation of the pandemic has been done. We investigate the impact of five indices derived from 12 policies in the Oxford COVID-19 Government Response Tracker dataset and the Korean government's index, which is the social distancing level implemented by the Korean government in response to the changing pandemic situation.

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White-light-emitting materials have received significant attention because of their potential application in lighting, displays, and sensors. However, it is a challenge to obtain white light from one phosphor, because the basic requirement of the white light emission spectrum is that it should be wide enough to cover the entire visible light region. In this study, we have designed and demonstrated a white-light-emitting PMMA-CBS-127/PVP-coumarin 6/PAN-rhodamine B (PSCR) fibrous membrane, which was prepared through a triphasic electrospinning method.

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In this study, mesoporous nickel cobaltite (NiCoO) nanorods as electrode materials for high-performance hybrid supercapacitor were fabricated onto Ni foam by a simple and cost effective oxalic acid (OA) assisted rapid co-precipitation method. The effects of different metal precursors (NCO-Nitrate, NCO-Chloride and NCO-Acetate) on the electrochemical capacitive properties were studied. FE-SEM analysis confirmed that all samples exhibited highly dense mesoporous NiCoO nanorods vertically grown on the surface of Ni foam with excess accessible surfaces and unique sizes and morphologies.

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Herein, we outline the fabrication of highly porous three-dimensional carbon-fiber network anchored with uniform metallic cobalt (Co) via electrospinning and subsequent post-modification approaches. First, cobalt acetate solution saturated electrospun polyacrylonitrile (PAN) nanofibrous mat was subjected to sodium borohydride (NaBH) solution which results in the fabrication of three dimensional (3D) hierarchical multilayer network. Restructuring of the 2D mat into multilayered sponges with metal particles entrapment is attributed to the in-situ generated hydrogen gas into the interconnected pores of the fibrous network simultaneous with reduction of cobalt salt into metallic cobalt by NaBH.

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Fly ash (FA), a solid waste generated in thermal power plants, is considered an environmental pollutant. Therefore, measures must be taken to dispose of FA in an environmentally friendly manner. In this paper, an electrospinning technique was employed to incorporate FA particles onto zinc oxide nanofibers (ZnO NFs), and the product (FA/ZnO composite) was used for the removal of methylene blue (MB) from the water.

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Inorganic luminescent materials as one of the important high-performance materials are widely used for industry and scientific research, mainly owing to their outstanding luminescence properties. However, inorganic luminescent materials are typically brittle and inelastic, which greatly limit their use in practical applications, particularly in flexible optoelectronic devices. In this work, it is shown that "plum-pudding" like CsPbBr /Cs PbBr perovskite crystals anchor onto Al O -La O (CCAL) nanofibrous membranes, which are synthesized via a facile electrospinning and subsequent supersaturated recrystallization process.

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A combination of electrospinning technique and hydrothermal process was carried out to fabricate zinc oxide nano-flakes wrapped carbon nanofibers (ZnO/CNFs) composite as an effective electrode material for supercapacitor. The morphology of the as-synthesized composite clearly revealed that the carbon nanofibers were successfully wrapped with ZnO nano-flakes. The electrochemical performance of the as-synthesized nanocomposite electrode was evaluated by the cyclic voltammetry (CV), galvanostatic charge-discharge (GDC), and electrochemical impedance spectroscopy (EIS), and compared with the pristine ZnO nanofibers.

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Wire type supercapacitors with high energy and power densities have generated considerable interest in wearable applications. Herein, we report a novel NiCoS-decorated 3D, porous Ni film@Ni wire electrode for high performance supercapacitor application. In this work, a facile method is introduced to fabricate a 3D, porous Ni film deposited on a Ni wire as a flexible electrode, followed by decoration with NiCoS as an electroactive material.

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This study investigates three different strategies for anode surface treatment by doping superficial nitrogen groups on the anode surfaces of carbon cloth (CC) and carbon paper (CP). The chosen anodes were hydrothermally treated in the presence of an ammonia solution (AST), a mixture of nitric acid and sulfuric acid (AHT), and solid urea (UT) at 180 °C for 3 h. The utilized characterization techniques confirmed doping of nitrogen on the anode surfaces and a decrease in the oxygen-bonded carbon content.

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Water in the world is becoming an increasingly scarce commodity and the membrane technology is a most effective strategy to address this issue. However, the fouling and low flux of the polymeric membrane remains the big challenges. Novel modified Polyvinylidene fluoride (PVDF) membrane was introduced, in this work, using a novel treatment technique for an electrospun polymeric PVDF membrane to be used in oil/water separation systems.

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Keratin biomaterial has been used in regenerative medicine owing to its in-vivo and in-vitro biocompatibility. The present study was aimed to investigate the hair growth promoting activity of keratin extract and its mechanism of action. Keratin extract was topically applied on the synchronized depilated dorsal skin of telogenic C57BL/6 mice and promoted hair growth by inducing the anagen phase.

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In this study, we present a highly efficient and economical solution called as 'in situ hydrogenation' for preparation of highly conductive thin film electrode based on silver nanodendrites. The silver nanodendrite (AgND)/cellulose acetate (CA) thin film electrodes exhibited sheet resistance ranging from 0.32ohm/sq to 122.

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Development of photocatalytic materials with magnetic and antibacterial properties is highly desirable in wastewater treatment. In this study, a novel magnetically separable silver-iron oxide nanoparticles (Ag-FeO NPs) decorated graphitic carbon nitride (g-CN) nanocomposite via hydrothermal treatment has been presented for the multifaceted applications. The physiochemical properties of the as-synthesized ternary nanocomposite were characterized by the field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) studies.

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A novel and efficient CeO-doped MnO nanorods decorated reduced graphene oxide (CeO-MnO/RGO) nanocomposite was successfully synthesized via hydrothermal method. The growth of the CeO doped MnO nanorods over GO sheets and reduction of GO were simultaneously carried out under hydrothermal treatment. The morphology and structure of as-synthesized nanocomposite were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which revealed the formation of CeO-MnO decorated RGO nanocomposites.

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We report the hierarchically assembled nanofibers created by LbL self-assembly depending on the PSS-PAA fraction in the blend solutions and pH during bulid-up of the PAH/(PSS-PAA) multilayer films. The multilayer [(PEI/blend)/(PAH/blend)4] films with ρPAA (PSS-PAA fraction in the blend solutions) = 0.0 in the blend solution exhibited surface morphologies of randomly isolated globular clusters, while at ρPAA = 0.

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Rapid diagnostic tests (RDTs) can detect anti-malaria antibodies in human blood. As they can detect parasite infection at the low parasite density, they are useful in endemic areas where light infection and/or re-infection of parasites are common. Thus, malaria antibody tests can be used for screening bloods in blood banks to prevent transfusion-transmitted malaria (TTM), an emerging problem in malaria endemic areas.

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The design and development of an economic and highly active non-precious electrocatalyst for methanol electrooxidation is challenging due to expensiveness of the precursors as well as processes and non-ecofriendliness. In this study, a facile preparation of core-shell-like NiCo2O4 decorated MWCNTs based on a dry synthesis technique was proposed. The synthesized NiCo2O4/MWCNTs were characterized by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and selected area energy dispersive spectrum.

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Flexible membranes created from porous carbon nanofibers (CNFs) hold great promise in the next generation wearable energy storage devices, but challenges still remain due to the poor mechanical properties of porous carbon nanofibers. Here, we report a facile strategy to fabricate elastic and hierarchical porous CNF membranes with NiFe2O4 nanocrystals embedded via multicomponent electrospinning and nano-doping methods. Benefiting from the scattering effect of NiFe2O4 nanocrystals and graphitized carbon layers for the condensed stress, the resultant CNF membranes exhibit an enhanced elasticity with a bending radius <12 μm, rapid recovery from the deformations, and a superior softness.

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Hierarchical Ag3PO4/TiO2 nanocomposite fibers were prepared by combining electrospinning technique and hydro-thermal growth method. As-synthesized samples were characterized by using field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Photoluminescence (PL), and Fourier transform infra-red (FT-IR) spectroscopy. The FE-SEM image revealed a uniform decoration of Ag3PO4 nanoparticles without aggregation on primary TiO2 nanofibers.

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High levels of anti-dengue IgM or IgG can be detected using numerous rapid diagnostic tests (RDTs). However, the sensitivity and specificity of these tests are reduced by changes in envelope glycoprotein antigenicity that inevitably occur in limited expression systems. A novel RDT was designed to enhance diagnostic sensitivity.

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Novel luminescent and amorphous La2O3-ZrO2:Eu(3+) (LZE) nanofibrous membranes with robust softness are fabricated for the first time via a facile electrospinning technique. By incorporating zirconium oxide, the as-prepared lanthanum oxide nanofibrous membranes can be dramatically changed from extreme fragility to robust softness. Meanwhile, the softness and luminescent performance of LZE nanofibrous membranes can be finely controlled by regulating the doping concentration of zirconium oxide and europium in lanthanum oxide nanofibers.

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Biocompatible keratin-based hydrogels prepared by electron beam irradiation (EBI) were examined in wound healing. As the EBI dose increased to 60 kGy, the tensile strength of the hydrogels increased, while the percentage of elongation of the hydrogels decreased. After 7 days, the dehydrated wool-based hydrogels show the highest mechanical properties (the % elongation of 1341 and the tensile strength of 6030 g/cm(2) at an EBI dose of 30 kGy).

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Non-precipitation chitosan/silver nanoparticles (AgNPs) in 1% acetic acid aqueous solution was prepared from chitosan colloidal gel with various contents of silver nitrate via electron beam irradiation (EBI). Electrospun chitosan-based nanofibers decorated with AgNPs were successfully performed by blending poly(vinyl alcohol). The morphology of as-prepared nanofibers and the size of AgNPs in the nanofibers were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM).

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