• 제목/요약/키워드: layer-by-layer method

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CrN 코팅구조에 따른 Polymer Electrode Membrane Fuel Cell 금속분리판의 부식특성 비교 (Comparison of Corrosion Behavior of CrN Coated SUS316L with Different Layer Structure for Polymer Electrode Membrane Fuel Cell Bipolar Plate)

  • 백정호;한원규;강성군
    • 한국재료학회지
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    • 제20권4호
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    • pp.187-193
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    • 2010
  • Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

UV 레이저에 의한 블라인드 비아홀 가공 (Blind via Hole manufacturing technology using UV Laser)

  • 장정원;김재구;신보성;장원석;황경현
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.160-163
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    • 2002
  • Micro via hole Fabrication is studied by means of minimizing method to circuit size as many electric products developed to portable and minimize. Most of currently micro via hole fabrication using laser is that fabricate insulator layer using CO2 Laser after Cu layer by etching, or fabricate insulator layer using IR after trepanning Cu by UV. In this paper, it was performed that a metal layer and insulator layer were worked upon only one UV laser, and increase to processing speed by experiment.

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Opaque 도재의 도포 방법이 치과용 합금과 도재간의 결합 강도에 미치는 영향 (EFFECT OF TWO OPAQUING TECHNIQUES ON METAL-CERAMIC BOND STRENGTH)

  • 장일성;이선형
    • 대한치과보철학회지
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    • 제34권3호
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    • pp.475-488
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    • 1996
  • The opaque porcelain layer of porcelain-fused-to-metal(PFM) restoration is critical for the success of PFM restoration because it is the first layer placed over the treated alloy. But, the methods of opaquing technique have not been confirmed. Usually, the one layer method and two layer method have been used for the application of opaque porcelain. In the past, alloys with porcelain veneers which have been used successfully have contained various precious metals. Recent increase in the cost of precious metals stimulates considerable interest in nonprecious alloys. Although nickel-chromium alloys and nickel-chromium-beryllium alloys have been widely used, the use of cobalt-chromium alloys would be gradually increased with elimination of any potential risk of nickel-related allergic responses and/or beryllium-related toxic responses. This investigation examined one- and two-layer opaque porcelain applications to determine the effect on the bond strength of titanium added cobalt-chromium metal ceramic alloy. Bond strength of Ceramco II porcelain to titanium added cobalt-chromium alloy(2Dentitan) and gold-platinum-palladium alloy(Degudent H) were evaluated by direct shear bond strength test with Instron universal testing machine. The results were as follows; 1. When the mean shear bond strength of each experimental group were compared in $0.25cm^2$ unit area, the titanium added cobalt-chromium alloy/two layer method exhibited the greatest strength(79.7kg), followed by titanium added cobalt-chromium alloy/one layer method(76.2kg), gold-platinum-palladium alloy/two layer method(71.4kg), gold-platinum-palladium alloy/one layer method(64.2kg). 2. No significant differences in bond strength were recorded between the two opaquing techniques for gold-platinum-palladium alloy and titanium added cobalt-chromium alloy. 3. No significant differences in bond strength were recorded between the gold-platinum-palladium alloy and the titanium added cobalt-chromium alloy.

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Ni buffer layer를 사용한 Si3N4/S.S316 접합체에서 접합계면의 미세구조 변화가 접합체의 기계적 특성에 미치는 영향 (Effects of Microstructural Change in Joint Interface on Mechanical Properties of Si3N4/S.S316 joint with Ni Buffer layer)

  • 장희석;박상환;권혁보;최성철
    • 한국세라믹학회지
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    • 제37권4호
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    • pp.381-387
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    • 2000
  • Si3N4/stainless steel 316 joints with Ni buffer layer were fabricated by direct active brazing method (DIB) using Ag-Cu-Ti brazing alloy only and double brazing method (DOB) using Ag-Cu brazing alloy with Si3N4 pretreated with Ag-Cu-Ti brazing alloy. For the joint brazed by DIB method, Ti was segregated at the Si3N4/brazing alloy interface, but was not enough to form a stable joint interface. In addition, large amounts of Ni-Ti inter-metallic compounds were formed in tehbrazing alloy near the joint interface, which could deplete the contents of Ti involved in the interfacial reaction. However, for the joint brazed by DOB method, segregation of Ti at the joint interface were enough to enhance the formation of stable interfacial reaction products such as TiN and Ti-Si-Ni-N-(Cu) multicompounds, which restricted the formation of Ni-Tio inter-metallic compounds in the brazing alloy during brazing with Ni buffer layer. Fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was much improved by using DOB method rather than DIB method. It could be deduced that the differences of fracture strength of the joint with Ni buffer layer depending on brazing process adapted were directly affected by the formation of stable joint interface and the change in microstructure of the brazing alloy near the joint interface. It was found that fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was gradually reduced as the thickness of interface. It was found that fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was gradually reduced as the thickness of Ni buffer layer in the joint was increased from 0.1 mm to 10 mm. It seems to due to the increased residual stress in the joint as the thickness of Ni buffer layer is increased. The maximum fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was 386 MPa, and the fracture of joint was originated at Si3N4/brazing alloy joint interface and propagated into Si3N4 matrix.

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점탄성 제진재를 이용한 비구속형 제진강판의 최적설계에 관한 연구 (A Study on Optimum Design of an Unconstrained Damping Steel Plate by Using Viscoelastic Damping Material)

  • 유영훈;양보석
    • 소음진동
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    • 제5권4호
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    • pp.493-501
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    • 1995
  • Optimum design of a viscoelastic damping layer which is unconstrainedly cohered on a steel plate is discussed from the viewpoint of the modal loss factor. Themodal loss factor is analyzed by using the energy method to the base steel plate and cohered damping layer. Optimum distributions of the viscoelastic damping layer for modes are obtained by sequentially changing the position of a piece of damping layer to another position which contributes to maximizing the modal loss factors. Analytical procedure performed by using this method simulated for 3 fundamental modes of an edge-fixed plate. Simulated results indicate that the modal loss factor ratios can be increase by as much as 210%, or more, by optimizing the thickness distribution of the damping layer to two times of the initial condition which is entirely covered. Optimum configurations for the modes are revealed by positions where added damping treatments become most effective. The calculated results by this method are validated by comparison with the experimental results and the calculated results obtained by the Ross-Ungar-Kerwin's model in the case of the layer is uniformly treated over the steel plate.

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와이브로 망에서 지수평활법을 이용한 핸드오버 지연 단축 기법 (Low-Latency Handover Scheme Using Exponential Smoothing Method in WiBro Networks)

  • 표세환;최용훈
    • 한국ITS학회 논문지
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    • 제8권3호
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    • pp.91-99
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    • 2009
  • 초고속 인터넷 서비스와 이동 통신의 발달, 그리고 Mobile Device 보급의 증가는 유비쿼터스(Ubiquitous) 기술의 발전을 촉진시키는 계기가 되었다. 와이브로 (WiBro, Wireless Broadband Internet) 시스템은 이동 중에도 무선 랜 (Wireless LAN) 보다 넓은 서비스 지원 영역에서 고속의 멀티미디어 서비스를 제공 받을 수 있는 MBWA(Mobile Broadband Wireless Access)기술이며, IP 기반의 백본 망(Backbone Network)로 구성된다. 이와 같은 무선 이동 통신 환경에서는 와이브로 시스템의 Layer 2(MAC Layer, Medium Access Control Layer)에서의 이동성 지원 기술뿐만 아니라 Layer 3(Network Layer)에서의 이동성 지원 프로토콜이 필요하며, 사용자가 이동 중에도 원활한 서비스를 제공받기 위해서는 핸드오버(Handovcr)의 지연 시간을 최소화 시켜야 한다. 따라서 본 논문에서는 IPv4 기반의 와이브로 망에서의 핸드오버 지연 단축 기법을 제안한다. 제안된 방법을 이동 단말(MS, Mobile Station)이 수신하는 신호 강도의 예측 값을 바탕으로 크로스 레이어 (Cross-Layer)기반의 고속 핸드오버 기법 (Fast Handover Scheme)을 적용하며, 지수평활법 (Exponential Smoothing Method)을 사용하여 예측 값을 계산한다. 모의 실험을 통해 기존의 방법과 제안된 방법을 비교, 분석하여 핸드오버 지연 시간의 단축을 증명한다.

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이온 빔 스퍼터법에 의한 BSCCO 박막의 순차 증착 (Layer-by-layer Deposition of BSCCO Thin Films Using Ion Beam Sputtering Method)

  • 박용필;이준웅
    • 한국전기전자재료학회논문지
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    • 제11권4호
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    • pp.334-339
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    • 1998
  • $Bi_2Sr_2CuO_x$(Bi-2201) thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering (IBS) method. During the deposition, 14 wt%-ozone/oxygen mixture gas of typical pressure of $5.0\times10^{-5}$ Torr is supplied with ultraviolent light irradiation for oxidation. XRD and RHEED investigations reveal that a buffer layer with compositions different from Bi-2201 is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

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A Service Composition using Hierarchical Model in Multiple Service Environment

  • Tang, Jiamei;Kim, Sangwook
    • 한국멀티미디어학회논문지
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    • 제18권9호
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    • pp.1091-1097
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    • 2015
  • Internet-of-Things (IoT) becomes one of the most promising future paradigms, which foresees enormous amounts of interoperable things and heterogeneous services. The goal of IoT is to enable all things connected and brings all kinds information and services to people. However, such a great deal of information may lead to cognitive overload or restrain in productivity of people. Thus, it is a necessity to build intelligent mechanisms to assist people in accessing the information or services they needed in a proactive manner. Most of previous related mechanisms are built on well-defined web services and lack of consideration of constrained resources. This paper suggests a services composition method by adapting a hierarchical model, which is a graph-based model composed of four layers: Context Layer, Event Layer, Service Layer and Device Layer. With a such multi-layer graph, service composition can be achieved by the iteration of layer by layer. Then, to evaluate the effectiveness of this proposed hierarchical model, a real-life emergency response dataset is applied and the experimental results are composed with the general probabilistic method and indicate that the proposed method is help for compositing multiple services while considering given context and constrained resources.

PEDOT를 이용한 CRT용 반사방지 및 대전방지 코팅 (An Antireflection and Antistatic Coatings for CRTs using PEDOT)

  • 김태영;김종은;이보현;서광석;김진열
    • 한국전기전자재료학회논문지
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    • 제15권1호
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    • pp.61-66
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    • 2002
  • A method for designing antireflection (AR) and antistatic (AS) coating layer by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR coating is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The poly(3,4-ethylenedioxythiophene) which has the surface resistivity of 10$^4$Ω/$\square$ is used as a conductive layer. Optical constant of each ARAS coating layers such as refractive index and optical thickness were measured by 7he spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the risible region. The reflectance of ARAS films on glass substrate was below 1 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results.

Tone농도의 Facter N 결정에 관한 연구 (A Study on the Decision Factor N of the Tone Density)

  • 안석출
    • 한국인쇄학회지
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    • 제10권1호
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    • pp.35-54
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    • 1992
  • Direct electrostatic coating method is simple, low cost and environmentally useful method. We are investigated on the coating of carrier transfer polymer layer on the carrier generate inorganic pigment layer using direct electrostatic coating method. The sample was obtained electrostatic deposite layer by fusing and calendering on the copper phthalocyanine. we could be found several polymer thin film shows good bond properties between film and pigment layer.

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