• Title, Summary, Keyword: 금속 필라멘트

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Improvement on resolution of mono-filament wire (초음파 팬텀 내 모노필라멘트의 해상력 개선에 대한 연구)

  • Ma, Sang-Chull;Kong, Young-Kun
    • Journal of radiological science and technology
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    • v.26 no.2
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    • pp.49-56
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    • 2003
  • The purposes of this study are to improve the ultrasound resolution of various nylon and metallic mono-filament wires, therefore, it was tested that it analyze on nylon mono-filament wire of 0.1 mm in A Co.'s ultrasonic phantom and synthesis of C15 g tissue mimicking materials(TMM), analyze resolution of nylon and metallic mono-filament wires in water and TMM. The results obtained were summarized as follows: 1. Metallic mono-filament wire of 0.1 mm and nylon mono-filament wire of 0.12 mm, 180 denier showed that it cleared dot echo pattern. 2. Metallic and nylon mono-filament wire of 0.2 mm showed that it cleared comet tail echo by reverberation artifact. 3. Nylon and metallic mono-filament wire of 0.1 mm showed that it can used for dead zone and axial resolution test. 4. Nylon mono-filament wire compared with metallic mono-filament wire showed that it satisfy elasticity and construction. 5. Degree of hardness of na not changed mono-filament's echo textures.

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Microstructure and Conductivity of Cu-Nb Microcomposites Fabricated by Bundling and Drawing Process (다발체형성과 인발공정에 의해 제조된 Cu-Nb 미세복합재료의 미세조직과 전도도)

  • Kwon, Hoi-Joon;Hong, Sun-Ig;Jee, Kwang-Koo
    • Korean Journal of Materials Research
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    • v.11 no.2
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    • pp.115-119
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    • 2001
  • The electrical properties of heavily drawn bundled Cu- Nb filamentary microcomposite wires were examined and correlated with the microstructural changes caused by thermomechanical treatments. The cross sectional shape of Nb filaments in wires fabricated by bundling and drawing appear straight or slightly curved. The different shape of Nb filaments is attributed to the break- up and cylinderization of Nb filaments during the bundling process at high temperatures. The resistivity of Cu-Nb microcomposites is predominantly controlled by electron scattering at Cu-Nb interfaces. The decrease of the conductivity below the annealing temperature of $400^{\circ}C$ is due to the increasing contribution of the scattering associated with coherency strains of needle- shaped precipitates. The slight decrease of the resistivity ratio (${\rho}_{295K}/{\rho}_{75K}$) is also due to the precipitation of Nb atoms. The increase in conductivity in Cu-Nb microcomposites at an annealing temperature of 50$0^{\circ}C$ is due to the coarsening and spheroidization of Nb filaments.

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Design of Filament Wound Composite Pressure Tanks (필라멘트 와인딩된 복합재 압력탱크의 설계 연구)

  • 김철웅;박재성;조인현;홍창선;김천곤
    • Composites Research
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    • v.15 no.1
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    • pp.9-20
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    • 2002
  • In this study, the design method of filament wound composite pressure tanks was established by using finite element analyses. Pressure tanks were designed with and without a load sharing metallic liner. A GUI(graphic user interface) program was developed to increase the efficiency of analyses. The replacement ratio was defined in order to replace a metal pressure tank with a composite one. Finally, the best design model that is satisfied with design requirements was suggested.

CeB6 필라멘트를 탑재한 저진공 주사전자현미경의 개발

  • Seol, In-Ho;Bae, Mun-Seop;Park, In-Yong;Jo, Bok-Rae
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.111.2-111.2
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    • 2016
  • 주사전자현미경은 시료표면에 전자빔을 주사하여 시료와 전자빔간의 상호작용으로 발생하는 이차전자(SE)와 후방산란전자(BSE)를 이용하여 시료표면을 관찰하는 장비이다. 일반적으로 텅스텐필라멘트를 사용하며, 10E-5 mbar이하 압력의 고진공에서 시료관찰이 이루어진다. 고진공 시료관찰시 도체 시료는 표면 코팅 없이 관찰이 가능하지만, 부도체 시료의 경우 전자빔에 의한 대전(Charging)현상이 발생하여 이미지가 왜곡되며, 이를 방지하기 위해 금, 백금 등의 금속을 표면에 코팅하여야 한다. 하지만 10E-1 mbar 이상 압력의 저진공에서는 부도체 시료도 전자빔에 의한 대전(Charging)현상이 발생하지 않아 생물시료 등의 부도체 시료를 표면코팅 없이 관찰할 수 있다. 본 발표에서는 현재 개발 중인 CeB6 필라멘트를 탑재한 저진공 주사전자현미경의 차동배기구조를 보여준다. 차동배기에 의해 가동 압력 10E-1 mbar이상의 저진공을 유지하는 시료실과 CeB6 필라멘트를 사용하기 위한 10E-6 mbar이하의 고진공을 유지하는 전자총실의 진공 배기특성을 보고한다.

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Background effect on the measurement of trace amount of uranium by thermal ionization mass spectrometry (열이온화 질량분석에 의한 극미량 우라늄 정량에 미치는 바탕값 영향)

  • Jeon, Young-Shin;Park, Yong-Joon;Joe, Kih-Soo;Han, Sun-Ho;Song, Kyu-Seok
    • Analytical Science and Technology
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    • v.21 no.6
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    • pp.487-494
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    • 2008
  • An experiment was performed for zone refined Re-filament and normal (nonzone refined) Re-filament to reduce the background effect on the measurement of low level uranium samples. From both filaments, the signals which seemed to come from a cluster of light alkali elements, $(^{39}K_6)^+$, $(^{39}K_5+^{41}K)^+$ and $PbO_2$ were identified as the isobaric effect of the uranium isotopes. The isobaric effect signal was completely disappeared by heating the filament about $2000^{\circ}C$ at < $10^{-7}$ torr of vacuum for more than 1.5 hour in zone refined Refilaments, while that from the normal Re-filaments was not disappeared completely and was still remained as 3 pg. of uranium as the impurities after the degassing treatment was performed for more than 5 hours at the same condition of zone refined filaments. A threshold condition eliminating impurities were proved to be at 5 A and 30 minutes of degassing time. The uranium content as an impurity in rhenium filament was checked with a filament degassing treatment using the U-233 spike by isotope dilution mass spectrometry. A 0.31 ng of U was detected in rhenium filament without degassing, while only 3 pg of U was detected with baking treatment at a current of 5.5 A for 1 hr. Using normal Re-filaments for the ultra trace of uranium sample analysis had something problem because uranium remains to be 3 pg on the filament even though degassed for long hours. If the 1 ng uranium were measured, 0.3% error occurred basically. It was also conformed that ionization filament current was recommended not to be increased over 5.5 A to reduce the background. Finally, the contents of uranium isotopes in uranium standard materials (KRISS standard material and NIST standard materials, U-005 and U-030) were measured and compared with certified values. The differences between them showed 0.04% for U-235, 2% for U-234 and 2% for U-236, respectively.

Metallic FDM Process to Fabricate a Metallic Structure for a Small IoT Device (소형 IoT 용 금속 기구물 제작을 위한 금속 FDM 공정 연구)

  • Kang, In-Koo;Lee, Sun-Ho;Lee, Dong-Jin;Kim, Kun-Woo;Ahn, Il-Hyuk
    • Journal of The Korea Internet of Things Society
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    • v.6 no.4
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    • pp.21-26
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    • 2020
  • An autonomous driving system is based on the deep learning system built by big data which are obtained by various IoT sensors. The miniaturization and high performance of the IoT sensors are needed for diverse devices including the autonomous driving system. Specially, the miniaturization of the sensors leads to compel the miniaturization of the fixer structures. In the viewpoint of the miniaturization, metallic structure is a best solution to attach the small IoT sensors to the main body. However, it is hard to manufacture the small metallic structure with a conventional machining process or manufacturing cost greatly increases. As one of solutions for the problems, in this work, metallic FDM (Fused depositon modeling) based on metallic filament was proposed and the FDM process was investigated to fabricate the small metallic structure. Final part was obtained by the post-process that consists of debinding and sintering. In this work, the relationship between infill rate and the density of the part after the post-process was investigated. The investigation of the relationship is based on the fact that the infill rate and the density obtained from the post-processing is not same. It can be said that this work is a fundamental research to obtain the higher density of the printed part.

Mechanical Properties and Electrical Conductivities of In-Situ Cu-9Fe-1.2X(X=Ag, Cr, Co) Microcomposite Wires (Cu-9Fe-1.2X (X=Ag, Cr, Co)계 미세복합재료전선의 기계적 특성 및 전기전도도)

  • Song, Jae-Suk;Im, Mun-Su;An, Jang-Ho;Hong, Sun-Ik
    • Korean Journal of Materials Research
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    • v.10 no.1
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    • pp.41-48
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    • 2000
  • In this study, microstructure and mechanical properties and electrical conductivities of in situ Cu-Fe-Xi(Xi=Ag, Cr or Co) alloy wires obtained by cold drawing combined with intermediate heat treatments have investigated. During cold working the primary and secondary dendrite arms are aligned along the drawing direction and elongated into filaments after deformation processing. The addition of Ag was found to be more effective in reducing the microstructural scale at the given draw ratio than that of Co or Cr throughout the drawing processing. The ultimate tensile strength and the conductivity of the Cu-Fe based composites containing Ag were higher than those of Cu-Fe composites containing Co or Cr. The good mechanical and electrical properties of Cu-Fe-Ag wires may be associated with the more uniform distribution of the finer filaments in the wires containing silver. The strength of Cu-Fe-Xi composites is dependent on the spacing of the Fe filaments in accord with a Hall-Petch relationship. The fracture surfaces of all the specimens showed ductile-type fracture and iron filaments occasionally observed on the fracture surfaces.

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Interpretation for inductive heating in MOCVO system to deposit white LED (백색 LED증착용 MOCVD장치의 유도 가열 해석)

  • Hong, Kwang-Gi;Ju, Jeong-Hun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.240-240
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    • 2009
  • 오늘날 반도체 기술의 획기적인 발전에 의해서 마침내 에디슨의 탄소 필라멘트 백열전구를 대체할 수 있는 "반도체 필라멘트"라 불리는 고출력 백색 LED (lighting emitting diode)가 차세대 조명광원으로 급부상하고 있다. 백색LED를 생산하기 위한 공정에서 MOCVD (유기금속화학증착)장비를 이용한 공정은 기판의 온도 균일도를 향상시키는 것이 매우 중요하다. 균일한 기판 온도를 갖기 위한 조건으로 기판과 induction heater의 간격, 가스의 흐름, 기판의 회전, 유도가열코일의 디자인 둥이 장비의 설계 요소이다. 본 연구에서는 기관과 induction heater의 간격에 따른 온도를 thermal imaging camera (Fluke, Ti-10)을 이용하여 측정하였다.

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Preparation of Polyurethane Filament by using the Electrospinning (전기방사를 이용한 폴리우레탄의 필라멘트 제조)

  • 차동일;안영환;길명섭;김학용;이덕래
    • Proceedings of the Korean Fiber Society Conference
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    • pp.384-385
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    • 2003
  • 최근 나노기술에 대한 관심이 급격히 부각되어짐에 따라 섬유에 있어서도 나노섬유 제조에 관하여 많은 관심이 모아지고 있다. 현재까지 알려진 나노섬유 제조법 중 공정, 설비 및 제조원가면에서 가장 유리한 전기방사법에 관하여 지대한 관심이 모아지고 있다. 전기방사법이란 고분자 용액이나 용융된 고분자에 고전압의 전하를 걸어주어 부직포를 집속 할 수 있는 금속소재의 콜렉터(collector)와 팁사이에 전기장을 형성시켜 부직포를 제조하는 방법이다 [1-3]. (중략)

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Composite Pressure Vessel for Natural Gas Vehicle by Filament Winding (필라멘트 와인딩 공정에 의한 천연가스 차량용 복합재료 압력용기)

  • 김병선;김병하;김진봉
    • Composites Research
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    • v.17 no.5
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    • pp.1-6
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    • 2004
  • Composite pressure vessels with HDPE (high density polyethlyne) liner with metal boss at each end were developed by Filament Winding Process. The vessel is composed of a dome-shaped part at each end and a cylinder-shaped part at the middle of the vessel. The environmental tests carried out for possible vessel materials such as High Density Polyethlyn (HDPE), resins and reinforcing fibers up to a year showed no significant damages. The boss was designed to minimize the gas leak which was verified by FEM analysis. Most ideal fiber tension was obtained by experimental method and the fiber volume fraction, $\textrm{V}_{f}$, obtained by image analyzer were 55.4 % in cylinder and 55.6 % in dome parts, respectively. Winding pattern is programmed to control the composite thickness in the dome areas such that the failure of the vessel may occur in the cylinder. During the cure, the vessel was rotated and a constant internal pressure of 0.62 bar was applied. From this, the vessel's burst pressure is improved by 28 %. The burst and fatigue tests for under-wound and fully wound vessel showed satisfactory results.