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446 results on '"Kim, Ho-Gi"'

51. Fabrication and gas sensing properties of hollow SnO2 hemispheres

Author

Hg Kim Ho-Gi Kim, Id Kim Il-Doo Kim, Dy Youn Doo-Young Youn, Ye Chang Young-Eun Chang, Avner Rothschild, Dj Yang Dae-Jin Yang, and Guy Ankonina

Subjects
Materials science, Fabrication, Hydrogen, technology, industry, and agriculture, Metals and Alloys, Nanowire, chemistry.chemical_element, Nanotechnology, General Chemistry, equipment and supplies, Catalysis, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Microsphere, Template, chemistry, Materials Chemistry, Ceramics and Composites, Sensitivity (control systems)
Abstract

Close packed arrays of hollow SnO2 hemispheres were prepared using PMMA microspheres as sacrificial templates for subsequent sputter-deposition of SnO2 films, leading to a threefold enhancement in gas sensitivity compared to non-templated (flat) films.

Published
2009

52. AC complex impedance investigation for RuO/sub 2/-glass composites

Author

No Kwang Soo, Kim Ho Gi, and Koo Bon Keup

Subjects
Materials science, General Engineering, Analytical chemistry, Conductivity, Industrial and Manufacturing Engineering, Spectral line, Electronic, Optical and Magnetic Materials, Ion, law.invention, Capacitor, Impurity, law, Volume fraction, Electronic engineering, Equivalent circuit, Electrical and Electronic Engineering, Electrical impedance
Abstract

As a function of RuO/sub 2/ volume fraction and heat treatment conditions, the AC complex impedance spectra of RuO/sub 2/-glass composites were investigated in the frequency range of 1 kHz-13 MHz, and equivalent circuits were analyzed based on the spectra. Because the amount of Ru ion in PbO-B/sub 2/O/sub 3/-SiO/sub 2/-Al/sub 2/O/sub 3/-ZnO system glass increases with increasing reaction temperature and time, the electronic properties of the matrix are changed due to the impurity ion. The samples reacted at low temperature and for short time periods exhibited vertical lines in complex impedance spectra plots, which indicates that the samples consisted of lone capacitor circuits. As the temperature and the time increased, the spectra consisted of semicircle arcs representing RC combination circuits. Because the glass gap distance between RuO/sub 2/ particles decreases with increasing RuO/sub 2/ content, the samples with greater RuO/sub 2/ content showed the change from a vertical line to semicircle arcs at a lower reaction temperature. >

Published
1991

57. Thermal analysis of the Bi-Sr-Ca-Cu-O system by an electrical property.

Author

Park, Jin Seong and Kim, Ho Gi

Subjects
*HIGH temperature superconductivity, *OXYGEN, *BISMUTH, *STRONTIUM, *CALCIUM
Abstract

Investigates the formation of the high-temperature superconducting phase in the bismuth-strontium-calcium-copper-oxygen system by measuring the electrical properties with temperature in an oxygen atmosphere. Temperature dependence of the electrical conductivity; Analysis of X-ray patterns; Results of differential thermal and thermogravimetric analysis.

Published
1989
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81. Characterization on Bandedge Electronic Structure of MgO Added Bi[sub 1.5]Zn[sub 1.0]Nb[sub 1.5]O[sub 7] Gate Dielectrics for ZnO-Thin Film Transistors

Author

Hg Kim Ho-Gi Kim, Dh Kim Dong-Hun Kim, Id Kim Il-Doo Kim, Jw Kim Jin-Woo Kim, Ht Seo Hyung-Tak Seo, and Ng Cho Nam-Gyu Cho

Subjects
Materials science, business.industry, Thin-film transistor, General Chemical Engineering, Electrochemistry, Optoelectronics, General Materials Science, Electronic structure, Dielectric, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, business, Characterization (materials science)
Published
2011

92. Low Voltage Operating InGaZnO[sub 4] Thin Film Transistors with Sputter-Deposited PMMA/High-k BST Stacked Gate Dielectric Layers

Author

Id Kim Il-Doo Kim, Ng Cho Nam-Gyu Cho, Hg Kim Ho-Gi Kim, and Dh Kim Dong-Hun Kim

Subjects
Materials science, business.industry, General Chemical Engineering, Gate dielectric, Substrate (electronics), Dielectric, Threshold voltage, Overlayer, Thin-film transistor, Electrochemistry, Optoelectronics, General Materials Science, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, business, Low voltage, High-κ dielectric
Abstract

This study reports the enhanced electrical properties of InGaZnO 4 thin film transistors (TFTs) with sputter-deposited poly(methyl methacrylate) (PMMA)/Ba 0.6 Sr 0.4 TiO 3 (BST) stacked gate dielectrics. A noticeable reduction in the leakage current density (∼10 -8 A/cm 2 at 0.3 MV) was achieved by coating a PMMA overlayer. The InGaZnO 4 TFTs utilizing the PMMA (30 nm)/BST (270 nm) stacked gate dielectrics exhibited a high on/off current ratio of 2.6 × 10 6 , a high field effect mobility of 10.2 cm 2 /V · s, and a low threshold voltage of 1.1 V. Using stacked gate dielectric layers, we realized the low voltage operating InGaZnO 4 TFTs on a poly(ethylene terephthalate) substrate.

Published
2010

93. Facile synthesis and electrochemical properties of RuO2 nanofibers with ionically conducting hydrous layer

Author

Id Kim Il-Doo Kim, Hg Kim Ho-Gi Kim, Dy Youn Doo-Young Youn, Hl Tuller Harry L. Tuller, and Ts Hyun Tae-Seon Hyun

Subjects
Horizontal scan rate, Materials science, Nanotechnology, General Chemistry, engineering.material, Electrochemistry, Electrospinning, Core (optical fiber), Coating, Chemical engineering, Nanofiber, Materials Chemistry, engineering, Fiber, Layer (electronics)
Abstract

The facile synthesis, by electrospinning of highly conductive RuO2 fiber mats as the conducting core of electrochemical capacitors, is reported. Electrospun RuO2 fiber mats, calcined at 400 °C, exhibited highly porous morphologies composed of crystalline RuO2 nano-particles with an average particle size of 10 nm. The highly conducting (σ = 288 S cm−1) fiber mats were used as the basis of a hybrid electrochemical capacitor in which the fiber mats served as the conducting core for electrochemically deposited hydrate RuO2·nH2O overlayers. These electrochemical capacitors exhibited superior characteristics: a high specific capacitance of ∼886.9 F g−1 (based on the mass of the hydrous RuO2 coating layer) at scan rate of 10 mV s−1 and high rate capability with a capacity loss of only 30% from 10 to 2000 mV s−1. This is attributed to the superior electron transport pathways provided by the fiber mat core to the upper ionically conducting hydrous RuO2 coating layer.

Published
2010

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