• Title/Summary/Keyword: Cho O

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GENERALIZED H$\ddot{O}$LDER ESTIMATES FOR THE $\bar{\partial}$-EQUATION ON CONVEX DOMAINS IN $\mathbb{C}^2$

  • Cho, Hong-Rae;Seo, Yeon-Seok
    • East Asian mathematical journal
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    • v.25 no.2
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    • pp.221-227
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    • 2009
  • In this paper, we introduce the generalized H$\ddot{o}$lder space with a majorant function and prove the H$\ddot{o}$lder regularity for solutions of the Cauchy-Riemann equation in the generalized Holder spaces on a bounded convex domain in $\mathbb{C}^2$.

The Non-Linear Characteristics of ZnO Devices. (ZnO 소자의 비직선 특성)

  • Hong, Kyung-Jin;Chon, Kyung-Nam;Cho, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05a
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    • pp.43-46
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    • 2001
  • The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.

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Property variations of undoped ZnO thin films with deposition conditions (증착조건에 따른 undoped ZnO 박막의 특성 변화)

  • Nam, Hyoung-Gin;Lee, Kyu-Hwang;Cho, Nam-Ihn
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.3
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    • pp.51-54
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    • 2008
  • In this study, we investigated variations in undoped ZnO thin film properties with working pressure, $O_2$/Ar ratio, and annealing ambient. Higher vacuum pressure during deposition was observed to bring about slower growth rate resulting in samples with better crystallinity as well as hole generation efficiency through formation of shallower oxygen interstitial. Given that $O_2$/Ar ratio is greater than unity, O provided from the ambient to ZnO during annealing was found to preferably situate at interstitial sites. When He was used for the second annealing, significant changes were not observed. On the other hand, O ambient caused increased density of oxygen interstitial, thereby making the film more intrinsic-like high resistivity ZnO.

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Simultaneous Monitoring of KVN 4 Bands toward Evolved Stars

  • Cho, Se-Hyung
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.2
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    • pp.112.2-112.2
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    • 2014
  • We propose simultaneous monitoring observations of 22 GHz $H_2O$ and 43/86/129 GHz SiO masers toward ~15 evolved stars in order to investigate spatial structure and dynamical effect from SiO to $H_2O$ maser regions including mass-loss process and development of asymmetry in circumstellar envelopes. We also aim at investigating mutual association and difference between SiO and $H_2O$ masers for establishing SiO and $H_2O$ maser models coupled to hydrodynamical model of circumstellar envelope. In addition, the correlation and difference of SiO maser properties among J=1-0, J=2-1, and J=3-2 transition masers are traced according to different type of stars for constraining SiO pumping models. These scientific goals and target sources were determined based on KVN single dish and VLBI feasibility test observations at 4 bands. As a total observing time of every 2 month monitoring, about 90 and 360 hours (in average per year) are required for single dish and VLBI observations, respectively. From the 2014B observing season, these monitoring observations will be derived as one of KVN key science programs.

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Effects of the Gas Atmosphere of ZnO Buffer Layers in the ZnO films grown on Si Substrates by RF Magnetron Sputtering (RF 스퍼터링으로 Si 기판위에 제작된 ZnO 박막에서 ZnO 버퍼층의 가스분위기 영향)

  • Park, Tae-Eun;Cho, Hyung-Koun;Kong, Bo-Hyun;Hong, Soon-Ku
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.7
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    • pp.656-661
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    • 2005
  • The effects of gas atmosphere and in-situ thermal annealing in buffet layers on the characteristic of the ZnO grown by RF magnetron sputtering have been investigated. It was shown that the introduction of buffer layers grown at the gas atmospheres of the mixed $Ar/O_2$ and the in-situ thermal treatment of the ZnO buffer layer improved the structural and optical properties. In addition, the ZnO films on the buffer layer thermal-annealed at $N_2$ gas ambience showed the strong emission of the near band gap exciton with narrow linewidth by combining the high-temperature growth of the ZnO film.

The Thermally Resistance Strength of LAS($Li_2O$-$Al_2O_3$-$SiO_2$)System(I) ($Li_2O$-$Al_2O_3$-$SiO_2$계 소지의 내열 강화특성(I))

  • Lee, Eung-Sang;Choi, Sung-Chul;Park, Hyun;Cho, Woo-Seog
    • Journal of the Korean Ceramic Society
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    • v.27 no.2
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    • pp.283-287
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    • 1990
  • The study was aimed at investigating sintering characteristics, the overall properties from the ternary Li2O-Al2O3-SiO2 system. This system, which was considered without additives and selected five compositions, was studied with variation of the amount of SiO2. The reactivity of the system was observed by D.T.A.. Characteristics of sintering, microstructure, property and stability of produced phase were studied. It was found that because the range of sintering was narrow and the temperature of sintering was close to the melting temperature, the sintering by the general method was difficult. Also, these linear thermal expansion coeffecients were measured.

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Preparation of SnO and SnO, SnO2 fine powder by hydrazine method (Hydrazine법에 의한 SnO, SnO2 미분말의 합성)

  • Kim, Kang-Min;Kim, Ki-Won;Cho, Pyeong-Seok;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.14 no.5
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    • pp.297-301
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    • 2005
  • Nanocrystalline SnO and $SnO_{2}$ powder have been prepared by hydrazine method. Sn-Hydrazine complex was formed by the reduction between aqueous $SnCl_{2}$ solution and hydrazine monohydrate. $SnO_{2}$ nano powder was prepared by the decomposition of Sn-Hydrazine complex at $450^{\circ}C$. When NaOH was added to Sn-hydrazine complex, SnO powder with nano-sheet morphology could be prepared. This can be attributed to the role of $OH^{-}$ ion as a reducing agent.

Morphological and Electrical Characteristics of nc-ZnO/ZnO Thin Films Fabricated by Spray-pyrolysis for Field-effect Transistor Application (전계효과트랜지스터 기반 반도체 소자 응용을 위한 스프레이 공정을 이용한 nc-ZnO/ZnO 박막 제작 및 특성 분석)

  • Cho, Junhee
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.1-5
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    • 2021
  • Field-effect transistors based on solution-processed metal oxide semiconductors has attracted huge attention due to their intrinsic characteristics of optical and electrical characteristics with benefits of simple and low-cost process. Especially, spray-pyrolysis has shown excellent device performance which compatible to vacuum-processed Field-effect transistors. However, the high annealing temperature for crystallization of MOS and narrow range of precursors has impeded the progress of the technology. Here, we demonstrated the nc-ZnO/ZnO films performed by spray-pyrolysis with incorporating ZnO nanoparticles into typical ZnO precursor. The films exhibit preserving morphological properties of poly-crystalline ZnO and enhanced electrical characteristics with potential for low-temperature processability. The influence of nanoparticles within the film was also researched for realizing ZnO films providing good quality of performance.

Carbohydrate Structure of N- and O-linked Oligosaccharides of Human Erythropoietin Expressed in Chinese Hamster Ovary Cells

  • Lee, Dong-Eok;Ha, Byung-Jhip;Kim, Suk-Joon;Park, Ji-Sook;Yoo, Ree-Ann;Oh, Myung-Suk;Kim, Hyun-Su
    • BMB Reports
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    • v.29 no.3
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    • pp.266-271
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    • 1996
  • A recombinant human erythropoietin (EPO), expressed in Chinese hamster ovary (CHO) cells, is glycosylated at Asn 24, Asn 38, Asn 83, and Ser 126. After release of the N-linked carbohydrate chains by $peptide-N^{4}-(N-acetyl-{\beta}-glucosaminyl)$ asparagine amidase F, the oligosaccharides were analyzed by FACE (Fluorophore-Assisted Carbohydrate Electrophoresis). The O-linked carbohydrate chain was separated by hydrazine, and analyzed by FACE. The monosacccharide composition of recombinant EPO showed man nose, fucose, galactose, N-acetylglucosamine, N-acetylneuraminic acid, and a trace of N-acetylgalactosamine, which are typical monosaccharides in the glycoproteins from the CHO cell. Sequences of N-linked and O-linked oligosaccharides were determined. The structure and composition of oligosaccharides attached to recombinant human EPO, expressed in the CHO cell, are identical to the reported oligosaccharide structure in human EPO isolated from urine.

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