• 제목/요약/키워드: Advanced material

검색결과 4,147건 처리시간 0.04초

Quantitative Evaluation of Machinability of Free-Cutting Phosphor Bronze Alloy by using a Piezoelectric Tool Dynamometer

  • Cho, Hoon;Lee, Byoung-Soo;Ryu, Ho-Yeun;Jo, Hyung-Ho
    • 한국주조공학회지
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    • 제27권5호
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    • pp.217-220
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    • 2007
  • 절삭특성은 재료를 원하는 형상으로 가공하기 위해 재료의 불필요한 부분을 제거할 경우 그 가공성이 쉽거나 어려움에 대한 정도로 전의될 수 있는데 동합금 소재의 절삭특성은 절삭시 발생된 칩의 형상이나 길이를 측정하거나 또는 공구계에 부착된 토오크 미터에 의해 절삭력을 간접적으로 측정하는 방법 등이 사용되어 오고 있다. 상기의 평가방 법은 절삭특성의 간접적인 평가방법이라는 한계와 정확도에 문제가 있는 실정이다. 본 연구에서는 압전형 공구동력계(Piezoelectric Tool Dynamometer)를 쾌삭인청동합금 피절삭물에 직접 부착하여 절삭가공시 절삭력은 정량적으로 직접 측정하고자 하였다. 쾌삭인청동합금의 소둔 열처리 시간이 증가할수록 결정립의 성장에 의한 연화현상과 납입자의 군집화(Clustering)는 관찰되었으나 그로 인한 절삭력 및 절삭에 필요한 에너지의 변화는 뚜렷하지 않았다.

Advanced Nanoimprinting Material for Liquid Crystal Alignment

  • Gwag, Jin-Seog;Oh-e, Masahito;Yoneya, Makoto;Yokoyama, Hiroshi;Satou, H.;Itami, S.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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    • pp.534-537
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    • 2007
  • To promote liquid crystal application of nanoimprint lithography, a polymer with new concept is proposed. The material consists of a polyamic acid for good LC alignment and an epoxy resin for good imprinting. The result of sum-frequency generation (SFG) vibrational spectroscopy proves that this material is a functionally gradient material. This material shows excellent capability as a nanoimprinting material as well as an LC alignment layer.

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Fabrication of Ultra Fine β-phase Ti-Nb-Sn-HA Composite by Pulse Current Activated Sintering

  • Woo, Kee-Do;Wang, Xiaopeng;Kang, Duck-Soo;Kim, Sang-Hyuk;Woo, Jeong-Nam;Park, Sang-Hoon;Liuc, Zhiguang
    • 한국분말재료학회지
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    • 제17권6호
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    • pp.443-448
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    • 2010
  • The $\beta$ phase Ti-Nb-Sn-HA bio materials were successfully fabricated by high energy mechanical milling and pulse current activated sintering (PCAS). Ti-6Al-4V ELI alloy has been widely used as biomaterial. But the Al has been inducing Alzheimer disease and V is classified as toxic element. In this study, ultra fine sized Ti-Nb-Sn-HA powder was produced by high energy mechanical milling machine. The $\beta$ phase Ti-Nb-Sn-HA powders were obtained after 12hr milling from $\alpha$ phase. And ultra fine grain sized Ti-Nb-Sn-HA composites could be fabricated using PCAS without grain growth. After sintering, the microstructures and phase-transformation of Ti-Nb-Sn-HA biomaterials were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The relative density was obtained by Archimedes principle and the hardness was measured by Vickers hardness tester. The $\beta$-Ti phase was obtained after 12h milling. As result of hardness and relative density, 12h milled Ti-Nb-Sn-HA composite has the highest values.

Iodine Doping of Pentacene and its Electrical Properties

  • Rahim, Abdur;Lee, Young-Kyu;Lee, Chi-Young;Lee, Jae-Gab
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2011년도 춘계학술발표대회
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    • pp.238.2-238.2
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    • 2011
  • Organic thin film transistors (OTFTs) have been attracting considerable attention because of their potential use in low-cost, large area, electronic devices such as flexible displays, biochemical sensors, and smart cards. In past several years, gold/pentacene has been frequently used in OTFTs because of the high mobility of pentacene and the high work function of gold. To improve the performance of the OTFTs contact area doping of pentacene with p-doping materials are well known. In this work we demonstrated selectively contact area doping of pentacene with Iodine vapor. For effective doping elevated pentacene layer under the source-drain area was deposited and exposed to Iodine vapor. We got better electrical performance for elevated pentacene structure rather than planer structure with relatively high field-effect mobility.

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White Light Emitting Diodes for Illumination

  • Choi, Kyoung-Jae;Park, Joung-Kyn;Kim, Kyung-Nam;Kim, Chang-Hae;Kim, Ho-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.1090-1092
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    • 2006
  • There is provided white light illumination system including a radiation source, a first luminescent material having a peak emission wavelength of about 575 to about 620 nm, a second luminescent material having a peak emission wavelength of about 495 to about 550 nm, which is different from the first luminescent material and a third luminescent material having a peak emission wavelength of about 420 to about 480 nm, which is different from the first and second luminescent materials. The LED may be a UV LED and the luminescent materials may be a blend of three phosphors. A human observer perceives the combination of the blue, green and red phosphor emissions as white light.

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The effect of laser energy on the preparation of iron oxide by a pulsed laser ablation in ethanol

  • Maneeratanasarn, P.;Khai, T.V.;Choi, B.G.;Shim, K.B.
    • 한국결정성장학회지
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    • 제22권3호
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    • pp.134-138
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    • 2012
  • Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained much attention because it is easy to control experimental parameters. Iron oxide magnetic nanoparticles have been prepared by a pulsed laser ablation of ${\alpha}-Fe_2O_3$ target in ethanol at different magnitude of laser energy of 1, 20, 40 and 80 mJ/pulse. It revealed that particle size increases with increasing laser energy. It could be concluded that 40 mJ/pulse is an optimum laser energy for the preparation of iron oxide nanoparticles with uniform size distribution. The nanoparticles are homogeneously dispersed in ethanol and their stability maintained for several months.

strict-feedback 비선형 시스템의 출력궤환 적응 신경망 제어기 (Adaptive Output-feedback Neural Control for Strict-feedback Nonlinear Systems)

  • 박장현;김일환;김성환;문채주;최준호
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2006년도 전력전자학술대회 논문집
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    • pp.526-528
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    • 2006
  • An adaptive output-feedback neural control problem of SISO strict-feedback nonlinear system is considered in this paper. The main contribution of the proposed method is that it is shown that the output-feedback control of the strict-feedback system can be viewed as that of the system in the normal form. As a result, proposed output-feedback control algorithm is much simpler than the previous backstepping-based controllers. Depending heavily on the universal approximation property of the neural network (NN) only one NN is employed to approximate lumped uncertain nonlinearity in the controlled system.

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