• 제목/요약/키워드: A.O.

검색결과 51,983건 처리시간 0.077초

CuO띠가 입혀진 ZnO 소결체의 일산화탄소에 대한 선택적 감지 특성 (Selective Sensing of Carbon Monoxide Gas in CuO banded ZnO Ceramics)

  • 신병철
    • 한국세라믹학회지
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    • 제30권10호
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    • pp.819-822
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    • 1993
  • The purpose of this paper is a investigation of sensing mechanism for the carbon monoxide gas in CuO infiltrated ZnO ceramics. Potential barriers between CuO and ZnO can explain the selective sensing of carbon monoxide gas in the physically contacted CuO/ZnO ceramics. A specimen having no potential barrier between CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO was painted on the non electrode sides of ZnO ceramics. The CuO painted ZnO ceramics showed that the sensitivityfor the carbon moxnoxide gas was 1.3 times as high as that for the hydrogen gas. It is almost same gas sensitivity as that of the CuO infiltrated ZnO ceramics.

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ZnGa2O4:Mn 형광체 합성 및 발광 특성에 관한 연구 (A study on luminescence a specific character and ZnGa2O4:Mn phosphor synthetic)

  • 김수용;지석근
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 2009년도 춘계학술대회
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    • pp.703-708
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    • 2009
  • 본 논문에서는 ZnO와 $Ga_2O_3$ 분말을 1:1의 mole비로 혼합하고 여기에 Mn을 첨가하여 Ar이나 진공 분위기에서 $ZnGa_2O_4$ : Mn을 합성하였다. 제작된 $ZnGa_2O_4$ : Mn의 발광 스펙트럼, 표면 사진 및 성분비를 측정하여 산소의 성분 변화가 발광 특성에 미치는 영향을 규명하고자 하였다. 또한 저온의 Photoluminescence(PL) 스펙트럼으로부터 Mn의 site symmetry가 발광 스펙트럼에 미치는 영향을 설명하였다.

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조대 Si입자분말을 사용한 질화반응 Si3N4의 치밀화 거동 (Densification Behavior of Reaction-Bonded Silicon Nitride Prepared by Using Coarse Si Powders)

  • 이주신;문지훈;한병동;박동수;김해두
    • 한국세라믹학회지
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    • 제39권1호
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    • pp.45-50
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    • 2002
  • 평균입경 25$\mu m$의 Si조대분말에 소결조제의 조성과 양을 변화시켜 질화반응 질화규소 (RBSN)세라믹스를 제조할 때 나타나는 치밀화 거동, 미세구조의 발달 및 기계적 특성에 대하여 고찰하였다. 6wt% $Y_2O_3$ + 1wt% $Al_2O_3$(6YlA)의 소결조제를 첨가한 경우에는 치밀화를 이루지 못하였으나, 6wt% $Y_2O_3+3\;wt%\;Al_2O_3+2\;wt%\;SiO_2(6Y3A2S)$와 9wt% $Y_2O_3$+1.5wt% $A1_2O_3$+ 3w% $SiO_2$(9Yl.5A3S)의 소결조제를 첨가하여 이론밀도에 가까운 치밀화를 이루었다. $1900^{\circ}C$에서 소결한 6Y3A2S시편의 경우, 960MPa의 높은 파괴강도값과 $6.5MPa.m^{1/2}$의 파괴인성값을 얻었다.

Atomic layer chemical vapor deposition of Zr $O_2$-based dielectric films: Nanostructure and nanochemistry

  • Dey, S.K.
    • E2M - 전기 전자와 첨단 소재
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    • 제16권9호
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    • pp.64.2-65
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    • 2003
  • A 4 nm layer of ZrOx (targeted x-2) was deposited on an interfacial layer(IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 30$0^{\circ}C$. Some as-deposited layers were subjected to a post-deposition, rapid thermal annealing at $700^{\circ}C$ for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous $ZrO_2$-rich Zr silicate containing about 15% by volume of embedded $ZrO_2$ nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-$ZrO_2$(t-$ZrO_2$) and monoclinic-$ZrO_2$(m-$ZrO_2$) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interfacial layer (IL) was partitioned into an upper Si $o_2$-rich Zr silicate and the lower $SiO_{x}$. The latter was sub-toichiometric and the average oxidation state increased from Si0.86$^{+}$ in $SiO_{0.43}$ (as-deposited) to Si1.32$^{+}$ in $SiO_{0.66}$ (annealed). This high oxygen deficiency in $SiO_{x}$ indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor(MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of $ZrO_2$ and $SiO_2$, and the capacitance in accumulation (and therefore, EOT and kZr-O) was frequency dispersive, trends well documented in literature. This behavior is qualitatively explained in terms of the multi-layer nanostructure and nanochemistry that evolves.ves.ves.

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$Al_{2}O_{3}$가 첨가된 지르코니아 산소센서의 제조 및 그 특성 (Fabrication of a Zirconia Oxygen Sensor Added with $Al_{2}O_{3}$ and Its Characteristics)

  • 손정덕;최시영
    • 센서학회지
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    • 제1권1호
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    • pp.93-100
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    • 1992
  • 이트리아 안정화(安定化) 지르코니아(92 mole% $ZrO_{2}$+8 mole% $Y_{2}O_{3}$)에 0.5 mole% $SiO_{2}$$0{\sim}2.0{\;}mole%{\;}Al_{2}O_{3}$가 첨가된 소결체의 소결성, 기계적 및 전기적 성질에 대하여 조사하였다. 소결밀도(燒結密度)는 0.5 mole% $Al_{2}O_{3}$가 첨가되었을 때 가장 높게 나타났으며 1.5 mole%이상 $Al_{2}O_{3}$가 첨가됨에 따라 감소하는 경향을 나타내었다. 비커스 경도(硬度)는 소결밀도(燒結密度)에 비례하여 나타났으며, 0.5 mole% $Al_{2}O_{3}$가 첨가되었을 때 가장 높은 전도성을 나타내었다. 일정한 산소분압(酸素分壓)에 따른 기전력 측정에서도 0.5 mole% $Al_{2}O_{3}$가 첨가되었을 매 가장 높았다. 제작된 산소(酸素)센서들의 응답특성(應答特性) 결과에서 $SiO_{2}$$Al_{2}O_{3}$가 각각 0.5 mole% 첨가된 센서의 응답특성이 가장 좋았다.

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기술수용모델을 이용한 외식 O2O 서비스 특성이 고객신념에 미치는 영향 연구 (The Effect of Food Online-to-Offline (O2O) Service Characteristics on Customer Beliefs using the Technology Acceptance Model)

  • 원준연;강형철;김병용
    • 한국조리학회지
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    • 제23권7호
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    • pp.97-111
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    • 2017
  • As a single-person household emerges as an important consumer group, an Online-to-Offline or Offlineto-Online(O2O) service market is rapidly growing. This study attempted to verify the effects of convenience and webrooming characteristics of O2O service using the Technology Acceptance Model (TAM). The purpose of this study was to investigate the effects of the convenience and webrooming of food O2O service on users' perceived ease of use and perceived usefulness, and the effects of perceived ease of use and perceived usefulness on purchase intention of O2O services. Using a convenience sampling technique, an online survey was conducted through Google survey from April 16 to April 30, 2017 and was distributed to 447 O2O service users. A total of 320 questionnaires were included in the final analysis. The results showed that convenience had a significant effect on users' perceived ease of use as well as perceived usefulness. In addition, users' perceived ease of use had a significant impact on users' perceived usefulness. Finally, both perceived ease of use and perceived usefulness positively affected users' purchase intention of O2O services. These findings suggest that differentiated events, promotions, and store information should be provided when launching O2O service because webrooming is a more important factor in enhancing perceived usefulness than the perceived ease of use.

Synthesis and Characterization of ZnO/TiO2 Photocatalyst Decorated with PbS QDs for the Degradation of Aniline Blue Solution

  • Lee, Jong-Ho;Ahn, Hong-Joo;Youn, Jeong-Il;Kim, Young-Jig;Suh, Su-Jeong;Oh, Han-Jun
    • 대한금속재료학회지
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    • 제56권12호
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    • pp.900-909
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    • 2018
  • A $ZnO/TiO_2$ photocatalyst decorated with PbS quantum dots (QDs) was synthesized to achieve high photocatalytic efficiency for the decomposition of dye in aqueous media. A $TiO_2$ porous layer, as a precursor photocatalyst, was fabricated using micro-arc oxidation, and exhibited irregular porous cells with anatase and rutile crystalline structures. Then, a ZnO-deposited $TiO_2$ catalyst was fabricated using a zinc acetate solution, and PbS QDs were uniformly deposited on the surface of the $ZnO/TiO_2$ photocatalyst using the successive ionic layer adsorption and reaction (SILAR) technique. For the PbS $QDs/ZnO/TiO_2$ photocatalyst, ZnO and PbS nanoparticles are uniformly precipitated on the $TiO_2$ surface. However, the diameters of the PbS particles were very fine, and their shape and distribution were relatively more homogeneous compared to the ZnO particles on the $TiO_2$ surface. The PbS QDs on the $TiO_2$ surface can induce changes in band gap energy due to the quantum confinement effect. The effective band gap of the PbS QDs was calculated to be 1.43 eV. To evaluate their photocatalytic properties, Aniline blue decomposition tests were performed. The presence of ZnO and PbS nanoparticles on the $TiO_2$ catalysts enhanced photoactivity by improving the absorption of visible light. The PbS $QDs/ZnO/TiO_2$ heterojunction photocatalyst showed a higher Aniline blue decomposition rate and photocatalytic activity, due to the quantum size effect of the PbS nanoparticles, and the more efficient transport of charge carriers.

기상 TCE 제거반응용 $CrO_x/TiO_2$계 복합 산화물 촉매 디자인 (A Design Approach to $CrO_x/TiO_2$-based Catalysts for Gas-phase TCE Oxidation)

  • 양원호;김문현
    • 대한환경공학회지
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    • 제28권4호
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    • pp.368-375
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    • 2006
  • 순수한 아나타제 구조로 이루어진 DT51D $TiO_2$$CrO_x,\;FeO_x,\;MnO_x,\;LaO_x,\;CoO_x,\;NiO_x,\;CeO_x,\;CuO_x$와 같은 단일 산화물 촉매를 각각 5 wt.% 담지하여 모델반응으로 선택한 기상 TCE 제거반응을 수행하였으며, 이로부터 얻어진 결과를 바탕으로 $CrO_x/TiO_2$-based 복합 산화물 촉매상에서 TCE 산화반응을 연구함으로써 유해 중금속의 사용량을 최소화하기 위한 최적의 촉매 디자인 방법을 도출하고자 하였다. DT51D $TiO_2$에 담지된 여러 단일 금속 산화물들 중에서 기상 TCE 제거반응에 대하여 $CrO_x$가 가장 우수한 촉매활성을 보이는 것으로 나타났으며, 반응온도의 함수로 얻어진 TCE 제거반응의 활성은 $CrO_x$의 담지량에 의존하였다. 5 wt.% $CrO_x$-based 복합 산화물 촉매는 10 wt.% $CrO_x$만으로 이루어진 단일 산화물 촉매와 거의 동일한 수준의 TCE 제거반응 활성을 보였을 뿐만 아니라 이 복합 산화물 촉매들은 10 wt.% $CoO_x,\;MnO_x,\;FeO_x,\;NiO_x$ 등과 같은 단일 산화물 촉매들보다 높은 반응활성을 갖는 것으로 나타났다. 단일 산화물 촉매의 반응활성과 비교하였을 때 5 wt.% $CrO_x$-based 복합 산화물 촉매상에서 TCE 제거반응 동안에 얻어지는 반응활성의 증가 정도는 $420^{\circ}C$ 이하의 반응온도 기준으로 약 $10{\sim}80%$ 이상이었다. 따라서, CVOCs 제거반응을 위하여 널리 사용되고 있는 단일 $CrO_x/Al_2O_3$ 촉매보다는 $CrO_x$의 사용량을 최소화하면서도 우수한 반응활성을 얻을 수 있는 $CrO_x/TiO_2$-based복합 산화물 촉매가 보다 바람직하며 하나의 대안적인 촉매 디자인 방법으로 응용될 수 있을 것으로 생각된다.

O2O서비스의 지속이용의도에 영향을 미치는 요인에 관한 연구 : 영화관 티켓 발권서비스를 중심으로 (A Study on Factors Affecting Intention to Continuous Use of O2O Service : Focused on Cinema Ticketing Systems)

  • 박소은;이성혜;지대범;최정일
    • 한국IT서비스학회지
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    • 제16권4호
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    • pp.197-212
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    • 2017
  • This study aims to investigate factors affecting the intention of continuous use of O2O service by referring new media adoption theory and value-based acceptance model for movie ticketing services. For this study, a questionnaire survey was conducted for users of tickets ticketing service of the cinema online (including mobile) within the last 6 months. A total of 500 copies was collected and 404 copies were analyzed excluding 96 copies because of errors. As a result of the analysis, the ease of use and service ubiquity has a positive effect on perceived functional value and perceived emotional value, and usability has a positive effect on perceived functional value. Compatibility and trialability has a positive effect on both perceived functional value and emotional value. Previous experience has a positive effect on both perceived functional value and perceived emotional value, and inertia has negative effect on perceived functional value. Finally, the perceived emotional value has a positive effect on the intention to continuous use, but perceived functional value appeared to have no significant effect. This study shows a theoretical implication for new technology-based services such O2O. It was suggested to establish a practical marketing strategy and help to activate the O2O service field.

TiO2에 담지된 금속 산화물 촉매상에서 TCE 산화분해반응 (Oxidative Decomposition of TCE over TiO2-Supported Metal Oxide Catalysts)

  • 양원호;김문현
    • 한국환경과학회지
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    • 제15권3호
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    • pp.221-227
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    • 2006
  • Oxidative TCE decomposition over $TiO_2$-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial $TiO_2$ were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D $TiO_2\;and\;CrO_x$ would be the respective promising support and active ingredient for the oxidative TCE decomposition. The $TiO_2-based\;CrO_x$ catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high $CrO_x$ contents for preparing $CrO_x/TiO_2$ catalysts might produce $Cr_2O_3$ crystallites on the surface of $TiO_2$, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported $CrO_x$-based bimetallic oxide systems offered a very useful approach to lower the $CrO_x$ amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.