• Title/Summary/Keyword: Stabilization layer

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Review of the Flame Stabilization Techniques using Cavity (Cavity를 이용한 화염안정화 기술 리뷰)

  • Lee, Tae Ho
    • Journal of the Korean Society of Propulsion Engineers
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    • v.20 no.4
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    • pp.104-111
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    • 2016
  • The flame stabilization is one of the topics which have to be solved for the airbreathing propulsion systems, using the entering air which is supersonic velocity as an oxygen sources. Making a recirculation zone with an eddy flow, installed the reducing velocity devices such as the bluff body, is the typical method of the flame stabilization. Recently using a cavity flame stabilization at the wall is an emerging technique as an effective method which extends the stabilization zone, and the related research papers have been published on the flow separation and reattachment, pressures and oscillations including length/depth ratios in the cavities. Even though, still there are lots of topics to study more in the cavity flame stabilization field as the preceding techniques, as well as the research and the development of the airbreathing propulsion system itself.

Strain Rates and OH Layer Characteristics in Stabilization Region for Turbulent Non-premixed Jet Flames Close to Blowoff (동축공기 난류제트확산화염의 화염날림 근처에서의 변형률 및 OH 특성)

  • Hwang, Jeongjae;Kim, Taesung;Yoon, Jisu;Yoon, Youngbin
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.211-213
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    • 2014
  • Simultaneous measurements of planar laser-induced fluorescence (PLIF) of OH radicals and particle image velocimetry (PIV) were used to investigate the strain rates and OH structure characteristics of turbulent syngas non-premixed jet flames close to blowoff. Mean values of the maximum principal strain rate on OH layer decreases with the axial distance, and its standard deviation is significantly large upstream. Strain rate on stabilization region of the stable flame is only about a half of that of the flame near blowoff.

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Design of Self Recurrent Neuro-Fuzzy Controller for Stabilization of Nonlinear System (비선형 시스템의 안정화를 위한 자기순환 뉴로-퍼지 제어기의 설계)

  • Tak, Han-Ho;Lee, In-Yong;Lee, Seong-Hyeon
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2007.04a
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    • pp.390-393
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    • 2007
  • In this paper, applications of self recurrent neuro-fuzzy controller to stabilization of nonlinear system are considered. The architecture of self recurrent neuro-fuzzy controller is fix layer, and the hidden layer is comprised of self recurrent architecture. Also, generalized dynamic error-backpropagation algorithm is used for the learning of the self recurrent neuro-fuzzy controller. To demonstrate the efficiency of the self recurrent neuro-fuzzy control algorithm presented in this study, a self recurrent neuro-fuzzy controller was designed and then a comparative analysis was made with LQR controller through an simulation.

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Thrust Vector Control and Discharge Stabilization in a Hall Thruster by Azimuthal Division of Propellant Flow Rate

  • Fukushima, Yasuhiro;Yokota, Shigeru;Komurasaki, Kimiya;Arakawa, Yoshihiro
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.574-578
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    • 2008
  • In order to achieve thrust vector control and discharge stabilization in Hall thrusters, the azimuthal nonuniformity of propellant flow rate in an acceleration channel was created. A plenum chamber was divided into two rooms by two walls and propellant flow rate supplied to each section was independently controlled. In a magnetic layer type Hall thruster, steering angle of up to ${\pm}2.3$ degree was achieved. In an anode layer type Hall thruster, discharge current oscillation amplitude was decreased with the normalized differential mass flow rate.

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Single-Layer Color Cholesteric Liquid Crystal Displays

  • Lu, Shin-Ying;Lin, Yu-hui;Chien, Liang-Chy
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.982-985
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    • 2007
  • The authors report methods of fabrication singlelayer color cholesteric liquid crystal displays (CLCDs). A single-layer CLCD has been prepared from a polymerstabilized cholesteric liquid crystal. The unique feature of the polymer stabilization is in that the electrically switched colors preserve high reflectivity. A bistable single-layer CLCD has been prepared by the formation of polymer barrier walls and light-tuned cholesteric pitches to reflect blue, green and red color sub-pixels.

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Glucose Diffusion Limiting Membrane Based on Polyethyleneimine (PEI) Hydrogel for the Stabilization of Glucose Sensor

  • Kim, Suk-Joon;Shin, Woonsup
    • Journal of Electrochemical Science and Technology
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    • v.12 no.2
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    • pp.225-229
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    • 2021
  • Commercially available continuous glucose sensors require the operation stability for more than two weeks. Typically, the sensor comprises a sensing layer and an over-coating layer for the stable operation inside the body. In the sensing layer, enzymes and mediators are cross-linked together for the effective sensing of the glucose. The over-coating layer limits the flux of glucose and works as a biocompatible layer to the body fluids. Here, we report the simple preparation of the flux-limiting layer by the condensation of polyethyleneimine (PEI), tri-epoxide linker, and trimethylolpropane triglycidyl ether (PTGE). The sensor is constructed by a layer-by-layer drop-coating of the sensing layer containing glucose dehydrogenase and the PEI-derived blocking layer. It is stable for more than 14 days, which is enough for the sensor in the continuous monitor glucose monitoring (CGM) system.

The Study on the Current Limiting Characteristics of YBCO Coated Conductor with Different kinds of Stabilization Layer Applied to SFCL Using Iron Core and Coil (철심과 권선을 이용한 전류제한기에 적용시킨 안정화층이 다른 YBCO Coated Conductor의 전류제한 특성에 관한 연구)

  • Lee, Dong-Heok;Du, Ho-Ik;Kim, Yong-Jin;Han, Byoung-Sung;Yim, Seong-Woo;Han, Sang-Chul;Lee, Jeong-Phil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.10
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    • pp.788-792
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    • 2010
  • The yttrium-barium-copper-oxide (YBCO) coated conductor, which supplement the fault of the existing superconducting current-limit materials YBCO thin film, bismuth-strontium-calcium-copper-oxide(BSCCO) wire and bulk, has been improved its mechanical weakness and has high index; hence, after quench YBCO coated conductor could limit the fault current effectively because of fast resistance occurrence speed. Furthermore, it has wide applicable area as an current limit material because it shows different resistance occurrence tendency by the thickness and kind of stabilization material sputtered on the superconducting layer. Therefore, many researchers are carrying out the study of application of YBCO coated conductor to superconducting fault current limiter (SFCL) for making high quality current limit element, based on resistance type. On the other hand, the study for other type except resistance type has been rarely conducted for the application of YBCO coated conductor to SFCL as an current limit element. Consequently, in this study, YBCO coated conductor with different stabilization layer Cu and Stainless steel, is applied to SFCL using iron core and coil, and examine the many index points as an current limit element, such as current limit characteristic, the tendency of resistance occurrence, response time, the temperature trend for stability.

A Fundermental Study on Stabilization in Municipal Waste Landfill Site (도시폐기물 매립지의 안정화에 관한 기초연구)

  • 김은호;김순호
    • Journal of Environmental Health Sciences
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    • v.27 no.1
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    • pp.56-62
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    • 2001
  • The investigation was carried out to analyze the generation and the composition of landfill gas generated from inserted pipe wells into the underground by boring operation and also study the undecomposed waste characteristics by open-cut test at S. waste landfill site in Pusan city. Pilot test was conducted for stabilization. The experimental results from this study were summerized as follows. ; Since COD matter was easuer decomposed than COD matter for continuously biological stabilization in underground, it seemed that BOD and CO $D_{Mn}$ were in the range of 854~4,813mg/$\ell$ and 1,156~6,977mg/$\ell$ and their ratio were generally as high as 0.55~0.74. As C $H_4$ compositions of generated gas were measured in the range of 37.36~60.1%, we could know that C $H_4$ gas was actively generated. Organic matters by open-cut test averaged 13.4~16.6% at each landfill layer, and considering rate of combustible compositions(36.2~66.5%) for landfilling wastes, they have been actively decomposed. The measured and theoretical values of generated gas in waste landfill site were almost similar to C $H_4$ 50.0% and 53.4%, $CO_2$ 39.63% and 45.24%, and after 0.5$^{\circ}C$ with heavy depth and long landfill period. From the results of pilot test for stabilization, after 180 days organic matters were actively decomposed beyond 2.2 times in facultative aerobic lystimeter(B) to exsiting anaerobic lysimeter(A). Therefore, it seemed that landfill site was of benefical to the conversion of facultative aerobic for stabilization.

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Study on Selection of HTS Wire for Fabrication of Fault Current-limiting Type HTS Cables (사고전류 제한형 초전도케이블 제작을 위한 초전도 선재 선정에 관한 연구)

  • Heo, Soung-Ouk;Kim, Tae-Min;Han, Byung-Sung;Du, Ho-Ik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.12
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    • pp.904-908
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    • 2013
  • When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through a high-capacity and high-$T_c$ superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate measure to protect it. Therefore, appropriate measures are needed to protect HTS cables. The fault-current-limiting HTS cable that was suggested in this study performs an ideal transport current function in normal operations and plays a role in limiting a fault current in abnormal operation (i.e., when a fault current is applied). It has a structure that facilitated its self-current-limiting ability through device change and reconfiguration in the existing HTS cable without extra switching equipment. To complete this structure, it is essential to investigate about the selection of the superconducting wire. Therefore, in this paper, HTS wire using two types of different stabilization layer is compared and examined the stability and current limiting properties under the existence of a fault current.