Publications by authors named "Seong-Il Kim"

Recently, we reported that device performance degradation mechanisms, which are generated by the γ-ray irradiation in GaN-based metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs), use extremely thin gate insulators. When the γ-ray was radiated, the total ionizing dose (TID) effects were generated and the device performance deteriorated. In this work, we investigated the device property alteration and its mechanisms, which were caused by the proton irradiation in GaN-based MIS-HEMTs for the 5 nm-thick SiN and HfO gate insulator.

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Supramolecular organic frameworks (SOFs) made of organic guest molecule and cucurbit[8]uril (CB[8]) in aqueous solution have great potential for diverse applications. Herein, we designed highly fluorescent zero-dimensional (0D) nano-ring SOF with CB[8] as a host and novel bent-shaped cyanostilbene guest. This host-guest complex successfully formed macrocyclic hexamer and showed significantly enhanced fluorescence (Φ =68 %) compared to non-assembled monomer (Φ =2 %).

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The device performance deterioration mechanism caused by the total ionizing dose effect after the γ-ray irradiation was investigated in GaN-based metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) for a 5 nm-thick SiN and HfO gate dielectric layer. The γ-ray radiation hardness according to the gate dielectric layer was also compared between the two different GaN-based MIS-HEMTs. Although HfO has exhibited strong tolerance to the total ionizing dose effect in Si-based devices, there is no detail report of the γ-ray radiation effects in GaN-based MIS-HEMTs employing a HfO gate dielectric layer.

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An enhancement-mode AlGaN/GaN metal-insulator-semiconductor high-electron- mobility-transistor was fabricated using a recess gate and CF plasma treatment to investigate its reliable applicability to high-power devices and circuits. The fluorinated-gate device showed hysteresis during the DC current-voltage measurement, and the polarity and magnitude of hysteresis depend on the drain voltage. The hysteresis phenomenon is due to the electron trapping at the AlO/AlGaN interface and charging times longer than milliseconds were obtained by pulse I-V measurement.

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This study examined the laxative effects of hot-water extracts of Thunb. (HD), Mazel (PM), and a 2:8 mixture of both (HP) in two chronic constipation models. For the loperamide-induced constipation model, animals were divided into an untreated group, negative control group (loperamide 4 mg/kg), positive control group (bisacodyl 4 mg/kg) group, and six treatment groups (HP 100 or 400, HD 50 or 100, and PM 100 or 400 mg/kg).

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Metal-insulator transition (MIT) in strongly correlated electronic materials has enormous potential with scientific and technological impacts in future oxide nanoelectronic devices. Although photo-induced MIT can provide opportunities to extend the novel functionality of strongly correlated electronic materials, there have rarely been reports on it. Here, we report MIT provoked by visible-near-infrared light in Ag-decorated VO nanorod arrays (NRs) because of localized surface plasmon resonance (LSPR) and its application to broadband photodetectors.

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Henoch-Schönlein Purpura (HSP, IgA vasculitis) is an immunoglobulin A (IgA) mediated disorder characterized by systemic vasculitis with variable presentation, frequently affecting the skin, mucous membrane, joints, kidneys, and rarely lungs and the central nervous system. Interestingly, enhanced production of interleukin-8 (IL-8) levels are found during active disease and increased levels have been reported in supernatants from human umbilical venous endothelial cells after stimulation with sera from patients affected by HSP. While corticosteroid therapy is currently the recommended treatment for HSP, dapsone, an anti-leprosy agent, has also recently been suggested to have therapeutic efficacy due to its ability to suppress IL-8.

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The performance of carbon nanotube (CNT)-based devices strongly depends on the adhesion of CNTs to the substrate on which they were directly grown. We report on the bond strength of CNTs grown on a carbon fiber (T700SC Toray), measured via in situ pulling of individual CNTs inside a transmission electron microscope. The bond strength of an individual CNT, obtained from the measured pulling force and CNT cross-section, was very high (∼200 MPa), 8-10 times higher than that of an adhesion model assuming only van der Waals interactions (25 MPa), presumably due to carbon-carbon interactions between the CNT (its bottom atoms) and the carbon substrate.

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In this study, we report simulation results for the optical properties of nanomesh-type electrodes for transparent electrode. Usually, indium tin oxide (ITO) is commonly used for transparent conductor to solar cell, display, LED and other electronic modules. However, the cost is high due to the rarity of indium.

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The core/shell-structured upconversion nanophosphors (UCNPs) and Cd-free CuInS(2)/ZnS quantum dots (QDs) were synthesized via coprecipitation and hot-injection methods, respectively, and they were applied to near infrared (NIR) photodetectors. The β-NaYF(4):Yb,Er/β-NaYF(4) UCNPs emitted intense visible light peaking at 522, 542, and 656 nm via (2)H(11/2), (4)S(3/2), and (4)F(9/2)→(4)I(15/2) transitions under excitation with 980 nm NIR light. The core/shell UCNPs showed 6.

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A novel nano-scale manipulator capable of handling low-dimensional materials with three-dimensional linear motion, gripping action, and push-pull action of the gripper was developed for an in situ experiment in transmission electron microscopy. X-Y-Z positioning and push-pull action were accomplished by a piezotubing system, combined with a specially designed assembly stage that consisted of a lever-action gripping tip backed by a push-pull piezostack. The gripper tip consisted of tungsten wire fabricated by electrochemical etching followed by a focused ion beam process.

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The evolution of copper-based interconnects requires the realization of an ultrathin diffusion barrier layer between the Cu interconnect and insulating layers. The present work reports the use of atomically thin layer graphene as a diffusion barrier to Cu metallization. The diffusion barrier performance is investigated by varying the grain size and thickness of the graphene layer; single-layer graphene of average grain size 2 ± 1 μm (denoted small-grain SLG), single-layer graphene of average grain size 10 ± 2 μm (denoted large-grain SLG), and multi-layer graphene (MLG) of thickness 5-10 nm.

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A systematic review, covering fabrication of nanoscale patterns by laser interference lithography (LIL) and their applications for optical devices is provided. LIL is a patterning method. It is a simple, quick process over a large area without using a mask.

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In this work, we use the electrical method to coat graphene oxide (GO) on ITO (Indium Tin Oxide) glass. The coated GO was characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The coated surface was monitored by scanning electron microscope (SEM) and atomic force microscope (AFM).

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Background: Intestinal ischemia-reperfusion injury induces intestinal mucosal barrier disruption, systemic inflammatory response syndrome, multiorgan failure, and death. The major pathway for the systemic inflammatory responses depends on nuclear factor kappa B (NF-κB). However, direct measuring of NF-κB in injured tissues is not routinely available.

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A bismuth telluride (BT)/indium selenide (IS) multilayer film was deposited at room temperature by rf magnetron sputtering on a sapphire substrate in order to investigate how the multilayered structure affects the microstructure and thermoelectric properties. The effect of annealing at different temperatures was also studied. The results were compared with those from a BT film with the same thickness.

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Purpose: To determine the pathogenesis of transient myopia after blunt eye trauma.

Methods: In one patient, the refraction of both eyes (the left eye was injured, but the right eye was not) was measured with an autorefractometer. The cycloplegic refraction was measured at the early stage of trauma and again 3 months after the blunt eye injury.

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Purpose: This study was performed to quantitatively evaluate the prevalence and risk factors of cataracts in Korean patients with type 2 diabetes mellitus.

Methods: Eight hundred fifty patients (males: 342, mean age: 58.07 +/- 8.

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