• Title/Summary/Keyword: H.W.O.S.T

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Influence of gas mixture ratio on the secondary electron emission coefficient (${\gamma}$) of MgO single crystals and MgO protective layer in surface discharge AC-PDPs

  • Lim, J.Y.;Jung, J.M.;Kim, Y.G.;Ahn, J.C.;Cho, T.S.;Cho, D.S.;Kim, J.G.;Kim, T.Y.;Kim, S.S.;Jung, M.W.;Choi, S.H.;Ko, J.J.;Kim, D.I.;Lee, C.W.;Seo, Y.;Cho, G.S.;Kang, S.O.;Choi, E.H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.117-118
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    • 2000
  • The secondary electron emission coefficient ${\gamma}$ of MgO single crystals according to the gas mixture ratio of Xe to Ne have been investigated by ${\gamma}-focused$ ion beam system. It is found that the MgO single crystals of (111) crystallinity has the highest ${\gamma}$ from 0.09(0.03) up to 0.16(0.04), while from 0.07(0.02) to 0.15(0.03) for (200) and from 0.06(0.01) to 0.13(0.02) for (220) crystallinity for operating Ne (Xe) ions ranging from 50eV to 200eV throughout this experiment. And it is found that the ${\gamma}$ ranged from 0.03 up to 0.06 for Ne-Xe mixtures are much smaller than those of 0.09 up to 0.16 for pure Ne ions under accelerating voltage ranged from 50V to 200V.

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Enhanced Magnetic Properties of BiFe1-$_xNi_xO_3$

  • Yoo, Y.J.;Hwang, J.S.;Park, J.S.;Kang, J.H.;Lee, B.W.;Lee, S.J.;Kim, K.W.;Lee, Y.P.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.183-183
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    • 2011
  • Multiferroic materials have been widely studied in recent years, because of their abundant physics and potential applications in the sensors, data storage, and spintronics. $BiFeO_3$ is one of the well-known single-phase multiferroic materials with $ABO_3$ structure and G-type antiferromagnetic behavior below the Neel temperature $T_N$ ~ 643 K, but the ferroelectric behavior below the Curie temperature $T_c$~1,103 K. In this study, the $BiFe_{1-x}Ni_xO_3$ (x=0 and 0.05) bulk ceramics were prepared by solid-state reaction and rapid sintering with high-purity $Bi_2O_32$, $Fe_3O_4$ and NiO powders. The powders of stoichiometric proportions were mixed, as in the previous investigations, and calcined at 450$^{\circ}C$ for $BiFe_{1-x}Ni_xO_3$ for 24 h. The obtained powders were grinded, and pressed into 5-mm-thick disks of 1/2-inch diameter. The disks were directly put into the oven, which has been heated up to 800$^{\circ}C$ and sintered in air for 20 min. The sintered disks were taken out from the oven and cooled to room temperature within several min. The phase of samples was checked at room temperature by powder x-ray diffraction using a Rigaku Miniflex diffractometer with Cu K${\alpha}$ radiation. The Raman measurements were carried out by employing a hand-made Raman spectrometer with 514.5-nm-excitation $Ar^+$ laser source under air ambient condition on a focused area of 1-${\mu}m$ diameter. The field-dependent magnetization measurements were performed with a superconducting quantum-interference-device magnetometer.

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Fabrication of long SmBCO coated conductor on IBAD-MgO template using co-evaporation method (동시증발법을 이용한 SmBCO/IBAD-MgO 박막 장선재 제조)

  • Ha, H.S.;Kim, H.S.;Ko, R.K.;Yoo, K.K.;Yang, J.S.;Kim, H.K.;Jung, S.W.;Lee, J.H.;Lee, N.J.;Kim, T.H.;Song, K.J.;Ha, D.W.;Oh, S.S.;Youm, D.;Park, C.;Yoo, S.I.;Moon, S.H.;Joo, J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.241-241
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    • 2007
  • We fabricated SmBCO coated conductors(CCs) on IBAD-MgO templates using co-evaporation method. IBAD-MgO templates consist of PLD-LMO/epi-MgO/IBAD-MgO/Ni-alloy and showed good in-plane texture of below FWHM 7 degree. Evaporation rates of Sm, Ba, and Cu were precisely controlled to get the optimum composition ratio after deposition process. To optimize the oxygen partial pressure of reaction region, wide range of the partial pressure was investigated from 1 mTorr to 15 mTorr. By reducing the oxygen partial pressure to 5mTorr, (103)grains in SmBCO layer have been increased. On the other hand, there were only (001)grains in SmBCO layer deposited at 15 mTorr $O_2$. Deposition temperature was also investigated from $600^{\circ}C\;to\;800^{\circ}C$ to make high Ic SmBCO CCs. SmBCO on IBAD MgO template showed that the Ic increased gradually at higher growth temperature to $800^{\circ}C$, which the highest Jc and Ic is $2.6\;MA/cm^2$ and 500 A/cm-w., respectively.

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Electrical and optical properties of ZnO : Al thin films deposited by Facing Targets Sputtering (대향타겟스퍼터법으로 증착된 ZnO : Al 박막의 전기적 광학적 특성)

  • Yang, J.S.;Seong, H.V.;Keum, M.J.;Park, Y.W.;Ka, C.H.;Kim, K.H.
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1478-1480
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    • 2001
  • ZnO : Al transparent conductive thin films were prepared by facing targets sputtering system with a DC power supply which can deposit a high quality thin films and control deposition condition in all range of $O_2$ gas ratio using ZnO target containing 8 at% of Al. Sputtering was carried out at a substrate temperature of R T with a DC current of 0.6 A and $O_2$ flow rate of 0 $\sim$ 0.9. The characteristics of ZnO : Al thin films was investigated by $\alpha$-step, four point probe, X-ray diffraction and UV/VIS spectrometer.

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SmBCO superconducting tape fabricated using co-evaporation method on Ni-W substrate (Ni-W 기판 위에 동시증발법으로 제조한 SmBCO 초전도선재)

  • Oh S.S.;Kim H.S.;Ha H.S.;Ko R.K.;Song K.J.;Ha D.W.;Lee N.J.;Yang J.S.;Kim T.H.;Jeong Y.H.;Youm D.
    • Progress in Superconductivity and Cryogenics
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    • v.8 no.3
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    • pp.9-12
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    • 2006
  • Batch type co-evaporation EDDC (Evaporation using Drum in Dual Chambers) system was recently manufactured to fabricate 100m - long SmBCO superconducting coated conductor. As a preliminary study before the fabrication of long tape. short CC samples have been fabricated using the EDDC system and their crystal texture and $I_c$ properties were investigated. $1.2 {\mu}m$-thick SmBCO layers were deposited on $CeO_2/YSZ/CeO_2$ buffered Ni-W tapes. $I_c$ of 128A/cm-w and corresponding $J_c$ of $1.1 MA/cm^2$ at 77K in self-field were obtained for SmBCO CC tape. In-field property of SmBCO CC was confirmed to be better than that of YBCO deposited by PLD.

Integration Process and Reliability for $SrBi_2$ $Ta_2O_9$-based Ferroelectric Memories

  • Yang, B.;Lee, S.S.;Kang, Y.M.;Noh, K.H.;Hong, S.K.;Oh, S.H.;Kang, E.Y.;Lee, S.W.;Kim, J.G.;Shu, C.W.;Seong, J.W.;Lee, C.G.;Kang, N.S.;Park, Y.J.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.1 no.3
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    • pp.141-157
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    • 2001
  • Highly reliable packaged 64kbit ferroelectric memories with $0.8{\;}\mu\textrm{m}$ CMOS ensuring ten-year retention and imprint at 125^{\circ}C$ have been successfully developed. These superior reliabilities have resulted from steady integration schemes free from the degradation, due to layer stress and attacks of process impurities. The resent results of research and development for ferroelectric memories at Hynix Semiconductor Inc. are summarized in this invited paper.

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Characteristics of Phenol Degradation by using UV/TiO2 Photocatalysis (UV/TiO2 광촉매반응에 의한 페놀의 분해 특성)

  • Shin, In-Soo;Choi, Bong-long;Lee, Seung-Mok
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.488-493
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    • 2004
  • The effects were examined from several conditions of $TiO_2$ photocatalysis reaction to phenols degradation by changing it's reacting conditions such as phenol concentration, pH, $TiO_2$ concentration, $H_2O_2$ concentration, flow rate, and intensity of ultraviolet rays. Phenol degradation was more efficient in low concentration of phenol, neutral pH. Phenol degradation appeared to increase as concentration of $TiO_2$ photocatalyst, that of $H_2O_2$ and intensity of ultraviolet rays increased. As $TiO_2$ dosage increased, initial rate constant k linearly increased. When $H_2O_2$ was injected more than optimum, phenol removal rate didn't increase in proportional to the change of $H_2O_2$ concentration as OH radicals was being consumed. When flow rate is less than $4.75m^3/m^2$ day, phenol removal efficiency appeared to decrease as ultraviolet rays transmission rate becomes low by $TiO_2$ suspension coated in photo reaction column. Meanwhile, initial rate constant according to light intensity change in less than $25mW/cm^2$ appeared to be in proportion to light intensity ($mW/cm^2$) Removal efficiency decreased about 12% after 180 minutes of reaction time while showed stable removal efficiency of 100% after 300 minutes when using regenerated $TiO_2$.