• 제목/요약/키워드: O26

검색결과 3,447건 처리시간 0.035초

폐과일껍질을 이용한 친환경 ZnO 나노분말 합성 (Enviroment-Friendly Synthesis of Nanocrystalline Zinc Oxide Particles Using Fruit Peel Extract)

  • ;송재숙;신평우;홍순익
    • 한국재료학회지
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    • 제26권6호
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    • pp.311-319
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    • 2016
  • In this study, an environment-friendly synthetic strategy to process zinc oxide nanocrystals is reported. The biosynthesis method used in this study is simple and cost-effective, with reduced solvent waste via the use of fruit peel extract as a natural ligation agent. The formation of ZnO nanocrystals using a rambutan peel extract was observed in this study. Rambutan peels has the ability to ligate zinc ions as a natural ligation agent, resulting in ZnO nanochain formation due to the presence of an extended polyphenolic system over the whole incubation period. Via transmission electron microscopy, successful formation of zinc oxide nanochains was confirmed. TEM observation revealed that the bioinspired ZnO nanocrystals were spherical and/or hexagonal particles with sizes between 50 and 100 nm.

MJH 해쉬 함수 역상 공격 (A Preimage Attack on the MJH Hash Function)

  • 이주영;김종성
    • 정보보호학회논문지
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    • 제26권2호
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    • pp.315-318
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    • 2016
  • 본 논문에서 우리는 이중 블록 길이 블록 암호 기반 해쉬 함수 MJH에 대한 새로운 역상 공격을 제안한다. MJH 해쉬 함수가 n 비트 블록 암호에 기반하여 2n 비트를 출력할 때, 기존 공격은 $O(2^{3n/2})$회의 질의를 요구하였으나, 본 논문에서는 이를 더욱 개선시켜 $O(n2^n)$의 계산량 및 같은 수준의 메모리를 사용하여 역상을 찾을 수 있음을 보인다.

Facile Modulation of Electrical Properties on Al doped ZnO by Hydrogen Peroxide Immersion Process at Room Temperature

  • Park, Hyun-Woo;Chung, Kwun-Bum
    • Applied Science and Convergence Technology
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    • 제26권3호
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    • pp.43-46
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    • 2017
  • Aluminum-doped ZnO (AZO) thin films were deposited by atomic layer deposition (ALD) with respect to the Al doping concentrations. In order to explain the chemical stability and electrical properties of the AZO thin films after hydrogen peroxide ($H_2O_2$) solution immersion treatment at room temperature, we investigated correlations between the electrical resistivity and the electronic structure, such as chemical bonding state, conduction band, band edge state below conduction band, and band alignment. Al-doped at ~ 10 at % showed not only a dramatic improvement of the electrical resistivity but also excellent chemical stability, both of which are strongly associated with changes of chemical bonding states and band edge states below the conduction band.

마이크로버블과 자외선/과산화수소 산화공정을 이용한 광산배수의 중금속 처리 특성 (The Treatment Properties of Heavy Metals in Acid Mine Drainage with Micro-bubble and UV/H2O2 Oxidation Process)

  • 정용준;정재억
    • 한국환경과학회지
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    • 제26권3호
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    • pp.303-309
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    • 2017
  • Aeration with low energy micro-bubble generation and $UV/H_2O_2$ processes was introduced to verify the possibility of oxidation treatment for acid mine drainage. During 10 hours of aeration with micro-bubbles, Fe and As concentrations were decreased to 18.1 and 61.8%, respectively, while Cu, Cd, Al were kept at influent concentrations. Other heavy metals such as Mn, Cr, Pb, Zn, and Ni concentrations fluctuated due to the repetition of oxidation and release. Twenty days of aeration indicated the oxidation possibility for Cu, Cd, and Al. With the employment of $UV/H_2O_2$ processes, more than 77% of Cu and Fe removed, whereas slightly more than 30% of Cd and Al removed.

대기압 반응로 내 코로나 이온을 이용한 나노입자 형상의 제어 (Corona ion Assisted Nano-Particle Morphology Control in an Atmospheric Pressure Furnace Reactor)

  • 안강호;윤진욱;김영원
    • 대한기계학회논문집B
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    • 제26권5호
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    • pp.710-715
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    • 2002
  • The spherical nonagglomerated and uniform nanometer-size SiO$_2$particles are synthesized by the injection of TEOS vapor, irons and reaction gas in a furnace. Ions are generated by corona discharge and these ions charge SiO$_2$particles. As a result, spherical, nonagglomerated and ultrafine particles are generated in various conditions. Their morphology, charging portion and size distribution are examined by using TEM, ESP and SMPS. As the applied voltage of electrode changes from 0 to 5.0 kV, it is observed that the melon diameter of SiO$_2$particle decreases from 94 nm to 42 nm.