• Title/Summary/Keyword: double layered

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Recent Development in Fabrication and Control of Layered-Double Hydroxide Nanostructures (층상 이중 수산화물 나노물질의 성장 제어기술 연구동향)

  • Jeon, Chan-Woo;Park, Il-Kyu
    • Journal of Powder Materials
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    • v.25 no.6
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    • pp.514-522
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    • 2018
  • Layered-double hydroxide (LDH)-based nanostructures offer the two-fold advantage of being active catalysts with incredibly large specific surface areas. As such, they have been studied extensively over the last decade and applied in roles as diverse as light source, catalyst, energy storage mechanism, absorber, and anion exchanger. They exhibit a unique lamellar structure consisting of a wide variety of combinations of metal cations and various anions, which determine their physical and chemical performances, and make them a popular research topic. Many reviewed papers deal with these unique properties, synthetic methods, and applications. Most of them, however, are focused on the form-factor of nanopowder, as well as on the control of morphologies via one-step synthetic methods. LDH nanostructures need to be easy to control and fabricate on rigid substrates such as metals, semiconductors, oxides, and insulators, to facilitate more viable applications of these nanostructures to various solid-state devices. In this review, we explore ways to grow and control the various LDH nanostructures on rigid substrates.

Silver (I)- Schiff-base complex intercalated layered double hydroxide with antimicrobial activity

  • Barnabas, Mary Jenisha;Parambadath, Surendran;Nagappan, Saravanan;Chung, Ildoo;Ha, Chang-Sik
    • Advances in nano research
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    • v.10 no.4
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    • pp.373-383
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    • 2021
  • In this work, silver nitrate complexes of sulfanilamide-5-methyl-2-thiophene carboxaldehyde (SMTCA) ligand intercalated Zn/Al-layered double hydroxide [Ag-SMTCA-LDH] were synthesized for the potential application as an antimicrobial system. The SMTCA ligand was synthesized by reacting sulfanilamide and 5-methyl-2-thiophene carboxaldehyde in methanol and further complexation with silver nitrate metal ions [Ag-SMTCA]. The structural analyses of synthesized compounds confirmed an intercalation of Ag-SMTCA into Zn/Al-NO3-LDH by flake/restacking method. SMTCA, Ag-SMTCA and Ag-SMTCA-LDH were characterized by 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis) spectrophotometer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). It was found that Ag-SMTCA-LDH exhibited good antimicrobial activity against both gram-positive (Bacillus subtilis, [B. subtilis], Staphylococcus aures, [S. aureus]) and gram-negative (Escherichia coli, [E. coli], Pseudomonas aeruginosa [P. aeroginosa]) bacteria as well as excellent antioxidant activity.

Performance Evaluation of Ti-Al-N coated Endmill by Arc ton Plating (아크이온플레이팅에 의한 Ti-Al-N코팅 엔드밀의 성능평가)

  • 이상용;강명창;김정석;김광호
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.04a
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    • pp.251-254
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    • 2002
  • The technique of high speed machining is widely studied in machining field. In this study, TiAIN single-layered and TiAIN/TiN double-layered coatings were applied to end-mill by an arc ion plating technique. Their performances were comparatively studied about cutting force, tool wear, tool life and surface roughness of workpiece under high speed cutting conditions. The TiAIN single-layer coated tool showed higher wear-resistance due to its higher hardness, while the TiAIN/TiN double-layer coated tool showed better performance for high metal removal, i.e., high fled per tooth condition due to its higher toughness. The surface roughness of the workpiece was not influenced by the wear amount of coated tools.

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Experimenal Study on Unsteady Double-Diffusive Convection in a Rectangle (사각형 용기내의 비정상 이중확산유동에 관한 실험적 연구)

  • 홍남호;김창수;현명택
    • Journal of Ocean Engineering and Technology
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    • v.8 no.1
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    • pp.105-113
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    • 1994
  • Double-diffusive convection induced by simultaneously-imposed lateral temperature and concentration gradients in a rectangular enclosure with aspect retio, 2.0 has been studied experimentally for adiabatic and isothermal horizontal boundary conditions. Visual observations show two distinct flow structures depending on the buoyancy ratio. The unicell flow structure is observed for a lower buoyancy ratio while the layered flow structure appears for a higher buoyancy ratio. There exists an unstable flow regime between two buoyancy ratios.

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Effect of Annealing on the Electrical Property and Water Permeability of ZTO/GZO Double-layered TCO Films Deposited by DC, RF Magnetron Co-sputtering (DC, RF 마그네트론 코스퍼터링법으로 증착한 ZTO/GZO 투명전도성막의 열처리 조건이 박막의 물성에 미치는 영향)

  • Oh, Sung-Hoon;Kang, Sae-Won;Lee, Gun-Hwan;Jung, Woo-Seok;Song, Pung-Keun
    • Journal of the Korean institute of surface engineering
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    • v.45 no.3
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    • pp.117-122
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    • 2012
  • ZTO/GZO double layered films were prepared on unheated non-alkali glass substrates. ZTO films were deposited by RF/DC hybrid magnetron co-sputtering using ZnO (RF) target and $SnO_2$ (DC) targets, and then GZO films were deposited by DC magnetron sputtering using an GZO ($Ga_2O_3$:5.57 wt%) target. These films were post-annealed at temperature of 200, $300^{\circ}C$ in air and vacuum ambient for 30 min. In the case of post-annealing in air, ZTO/GZO double layer showed relatively low resistivity change, compared to GZO single layer. Furthermore, ZTO/GZO double layer revealed low WVTR, compared to GZO single layer. Therefore, it can be confirmed that ZTO film doing a role with barrier for water or oxygen diffusion.

Influence of Bubble Sheet Applying Methods on Temperature of Exposed Joint Rebar at Wall Surface of Load-Bearing Wall Structure Building During Winter (동절기 벽식구조 건축물 벽부분의 버블시트 포설방법 변화가 이음부 노출철근의 온도에 미치는 영향)

  • Han, Cheon-Goo;Lee, Jea-Hyeon;Kim, Min-Sang
    • Journal of the Korea Institute of Building Construction
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    • v.17 no.2
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    • pp.149-155
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    • 2017
  • In this research, the surface covered curing method using the double-layered bubble sheet was evaluated. This double-layered bubble sheet has outstanding insulating performance with its low heat conductivity and high economic feasibility with its high durability. However, in the case of wall-typed building construction, the area of exposed rebar is curious on curing performance with the double-layered bubble sheet in spite of the double-layered bubble sheet showed favorable performance for slab. Therefore, in this research, regarding the actually constructed wall-typed apartment building, the most efficient curing method was suggested based on the evaluation of curing performance depending on temperature distribution depending on various location of covered or exposed rebar. As a result, the D method was determined as the most efficient curing method without any concern of early-age frost damage. However, by considering easiness of construction, the B method of covering the pieced double-layered bubble sheet on gap between rebars can be another option of desired result.

Study on the electric properties of layered $BaTiO_3$ films prepared new stacking method (새로운 방법으로 제조된 적층구조 $BaTiO_3$ 박막의 전기적 특성에 관한 연구)

  • Song, Man-Ho;Lee, Yun-Hi;Hahn, Taek-Sang;Oh, Myung-Hwan;Yoon, Ki-Hyun
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1129-1132
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    • 1995
  • In the preparation of the layered $BaTiO_3$ thin films with high performance, the new stacking method using the continuous cooling of the substrate was introduced. Amorphous/polycrystalline $BaTiO_3$ layered structure was confirmed by SEM and index of refraction. The layered $BaTiO_3$ thin films formed by the new stacking method showed such a high dielectric constant that the layered structure could not be explained by a stacking structure of the two defined layers but could only be explained by multi-layered structure, i.e. amorphous/micro crystalline/polycrystalline structure. The layered $BaTiO_3$ thin film with a thickness of 240 nm showed higher capacitance per unit area and breakdown strength than the double layered $BaTiO_3$ thin film prepared by the conventional stacking method. And well defined ferroelectric hysteresis leer was observed in the layered $BaTiO_3$ thin film with a thickness of 200 nm.

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Double-layered Peer-to-Peer Systems in MobileAd-hoc Networks (모바일애드혹 네트워크에서의 2계층 피어-투-피어 시스템)

  • Kim, Ji-Hoon;Yang, Sung-Bong
    • The KIPS Transactions:PartC
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    • v.17C no.1
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    • pp.61-68
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    • 2010
  • As the mobile technology advances, file searching among the mobile device users becomes more important. In this paper, we propose the uniform grid, greedy, and MIS P2P systems that have double-layered topology to search files efficiently for mobile ad-hoc networks. In these systems, peers are classified into two groups, super-peers and sub-peers, and each super-peer manages its neighboring sub-peers. In the proposed systems, each super-peer maintains the appropriate information of its sub-peers so that when a peer requests a file, the request is sent to its super-peers and then to neighboring super-peers. Hence the proposed systems could avoid multi-broadcasting and reduce network overheads. The experimental results show that the proposed systems outperform a single-layered P2P system in terms of the average number of messages to find target files. Especially the MISsystem improves by reducing the average number of messages by 48.9% while maintaining the same search accuracy.

Mechanical behaviors of multi-layered foam core sandwich composite (다층 구조 폼 코아 샌드위치 복합재의 기계적 거동 연구)

  • Oh J.O.;Yoon S.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.381-382
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    • 2006
  • The mechanical behaviors of multi-layered foam core sandwich composite were investigated through a 3-point bending test. The sandwich specimens were obtained from sandwich panel consisting of aluminum faces and urethane foam core. Three types of sandwich specimens such as a single structure, a double structure and a triple structure were considered. The span of sandwich specimens were varied from 170mm to 350mm. According to the results, the flexural and shear properties of multi-layered sandwich composite were found to be higher than those of single-layered sandwich composite.

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