• 제목/요약/키워드: Rare Earth

검색결과 975건 처리시간 0.043초

Trace Fossils from the Late Pleistocene Marginal Marine Deposits of Jeju Island, Korea: Implications for the Psilonichnus and Skolithos Ichnofacies

  • Kim, Jeong Yul;Kang, Ji Hyun
    • 한국지구과학회지
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    • 제39권1호
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    • pp.23-45
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    • 2018
  • Moderately diverse, but very abundant trace fossils are found from the Late Pleistocene deposits of Jeju Island, Korea. Vertical I-, Y- and U-shaped domichnia of annelids or decapods are, over 2500, extremely abundant, 3D network domichnia of callianassids are, over 200, very abundant, and small sinuous trails of nematode repichnia are, over 50, abundant in number. Horizontal trails attributable to polychaete or worm-like animals are, less than 50, common, but horizontal spreiten burrows, fish traces and crab trackways are, less than 10, rare in occurrence. Of these trace fossils, Taenidium barretti, Undichna britannica and Undichna unisulca represent the first record from the Pleistocene in Asia. Psilonichnus upsilon is the second record in Asia. Crab trackways probably produced by underwater punting gait of sideway walking crabs may represent the first record in the world. In addition, diverse and very abundant footprints of more than 500 hominids, more than 200 birds and more than 1000 mammals are closely associated with these invertebrate trace fossils. Trace fossil assemblage integrated with sedimentary facies is interpreted to have been formed in the marginal marine foreshore to backshore environment corresponding to the Psilonichnus and Skolithos ichnofacies.

LiCl-KCl 용융염에서 Cd-Li 금속을 이용한 U 및 란탄족의 환원반응 (Reductive reaction of U and Lanthanides using Cd-Li metal in LiCl-KCl Molten Salt)

  • 우문식;이병직;김응호;유재형
    • 한국방사성폐기물학회:학술대회논문집
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    • 한국방사성폐기물학회 2004년도 학술논문집
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    • pp.339-339
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    • 2004
  • 원자로를 이용하여 장수명핵종(long lived nucleus)을 소멸처리하는 과정에서 초우라늄(TRU, transuranium)과 희토류(RE, rare earth) 금속에 포함되어 있는 소량의 핵분열성(fissile) 물질인 우라늄을 제거할 필요가 있다. 본 실험은 LiCl-KCl 용융염계에서 전해제련법(Electrowinning)을 이용하여 용융염욕에 존재하는 우라늄을 제거하기 위하여 필요한 Cd-Li 양전극 물질을 제조하였고, 제조된 금속을 이용하여 우라늄 및 란탄족(Dy, Ce, Y, Nd, Gd) 금속의 환원 특성을 파악하였다.(중략)

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Waveguide Optical Matrix 용 졸-겔 코팅졸의 OH 함량 제어 (Control of Hydroxyl Group Content in Sol-Gel-Derived Sols for Waveguide Optical Matrix)

  • 안복엽;석상일;김주현;권정오
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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    • pp.55-55
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    • 2003
  • Recently, with the rapid development of the waveguide division multiplexing (WDM) systems for large capacity and flexibility of information network, the broad band 1.5$\mu\textrm{m}$ erbium-doped waveguide amplifier (EDWA) become important. The main factors affecting the performance of sol-gel-based waveguides are non-radiative relaxation channels due to rare-earth concentration quenching and to vibration of the OH groups Therefore, the sol-gel process has to be carefully controlled in order to minimize the residual OH content.

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Multiform Oxide Optical Materials via the Versatile Pechini-type Sol-Gel Process

  • Lin, J.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.1247-1250
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    • 2008
  • This presentation highlights work from the authors' laboratories on the various kinds of oxide optical materials, mainly luminescence and pigment materials with different forms (powder, core-shell structures, thin film and patterning) prepared by the Pechini-type sol-gel (PSG) process. The PSG process which uses the common metal salts (nitrates, acetates, chlorides etc) as precursors and citric acid (CA) as chelating ligands of metal ions and polyhydroxy alcohol (such as ethylene glycol or poly ethylene glycol) as cross-linking agent to form a polymeric resin on molecular level, allowing the preparation of many forms of luminescent materials.

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Advances in oxide thin-film phosphors for field emission displays

  • Hao, J.H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.263-267
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    • 2006
  • Advances in non-sulfur-containing phosphors from low-temperature synthesis of thin-films suitable for glass substrates are discussed. The effects of preparation process on the properties of a variety of rare-earth-doped oxide hosts are reviewed. Cathodoluminescent characteristics have been studied to determine the usefulness of oxide thin-film phosphors in field emission displays.

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수지자석 제조기법과 전자파 흡수체 및 식물 성장촉진기의 개발 (Development of manufacturing method of resin magnet. plant growth promote machine and electro wave absorbent material)

  • 이오걸
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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    • pp.13-16
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    • 2000
  • This paper developed a manufacturing method for resin magnet contained rare earth element and synthetic resin. Use this manufacturing method, developed a electro wave absorbent material and plant growth promote machine. Result of experiments shown to have excellent on bean sprouts cultivate, computer monitor, television monitor and cellular phone etc.

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Understanding Explosive Stellar Events Using Rare Isotope Beams

  • Chae, Kyungyuk
    • 천문학회보
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    • 제42권2호
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    • pp.66.1-66.1
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    • 2017
  • Nuclear reactions in explosive stars such as novae, X-ray bursts, and supernovae are responsible for producing many of the elements that make up our world. Exotic nuclei not normally found on earth can play an important role in these events due to the extreme conditions that occur in the explosion. A frontier area of research involves utilizing beams of radioactive nuclei to improve our understanding of these explosions and the implications on cosmic element production. At the future radioactive ion beam facility of Korea, RAON, we will measure astrophysically important reactions using exotic beams to probe the details of cosmic events. Details of RAON and possible day-1 experiments at the facility will be presented.

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