• Title/Summary/Keyword: 용융지 유동

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Analysis of Weld Pool Flow and Shape Considering the Impact of Droplets in GMAW (GMAW에서 용적입사를 고려한 용융지 유동 및 형상해석)

  • 박현성;이세현;엄기원
    • Journal of Welding and Joining
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    • v.16 no.2
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    • pp.40-47
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    • 1998
  • In the present study, depressions of the GMA weld pool due to the impact of droplet are numerically investigated. The numerical simulation is conducted on the basis of the Navier-Stokes equation and the volume of fluid(VOF) functions. The kinetic energy of transferring droplet makes a depression of the weld pool surface. The surface active element affects the depression of the weld pool. The droplets transferred efficiently to the bottom of the weld pool, along with electromagnetic force make the finger shape penetration at the high current GMAW.

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A Study on the Rheological and Morphological Properties for Immiscible Blends of Polyethylene and Nylon 6 (폴리에틸렌과 나일론6의 비상용 블렌드의 유변학적.형태학적 특성에 관한연구)

  • 홍성일
    • The Korean Journal of Rheology
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    • v.5 no.1
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    • pp.23-33
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    • 1993
  • 저밀도폴리에틸렌과 나일론6의 블렌드가 용융압출기의 사용에 의해 제조되었다. 제 조된 비상용 블랜드의 유변학적, 형태학적 분석을 통하여 이들사이의 상관관계를 조사하였 다. 전단속도, 계면장력, 용융점도, 분산상의 농도들에 대한 분산상의 크기의 의존성을 평가 하였다. 한편 신장유동에 의한 모폴로지 변화를 조사하기 위하여 기제조된 블렌드를 사용하 여 용융방사를 하였다. 이러한 방식실험으로부터 본연구에 사용된 저밀도 폴리에틸렌과 나 일론6는 분산상과 연속상의 신장점도의 상대적 크기에 무관하게 피브릴화가 되어 방사 연신 비의 증가에 의해 매우 가는 분산된 피브릴을 얻을수 있었다.

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Effect of aerodynamic drag force on liquid metal convection in GTA welding (GTA 용접시 발생하는 용융금속의 유동에 미치는 공기역학적 향력의 영향)

  • 나석주;김성도
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.575-583
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    • 1991
  • The weld pool convection problem that occurs during the stationary GTA welding has been studied, considering the four driving forces for weld pool convection, i.e., the electromagnetic force, the buoyancy force, the aerodynamic drag force, and the surface tension force at the weld pool surface. In the numerical simulation, the difficulties associated with the irregular moving liquid-solid interface have been successfully overcome by adopting a Boundary-Fitted Coordinate system. In the experiments to show the validity of the numerical analysis, a deep periphery and shallow centerpentrated weld pool shape was observed from the etched specimen. It could be revealed that this type of weld pool shape could be simulated, only when some of aerodynamic drag force distributions are considered. Although slight disagreement arose, the calculated and the observed weld pool shapes were in a reasonable agreement.

Analysis of Flow Characteristics and Experiment of Conductive Liquid Metal Coupling Lorentz Force with Fluid Equation (전자력과 유동방정식을 결합한 전도성 용융금속의 유동특성 해석 및 실험)

  • Jeon, Mun-Ho;Lee, Suk-Won;Kim, Chang-Eob
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.7
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    • pp.1329-1335
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    • 2009
  • This paper presents the flow characteristics in the fluid circulation loop using the tubular type linear induction motor(TLIM) electromagnetic pump. A TLIM pump was designed using the equivalent and genetic algorithm for the flow system of 40[1/min]. The flow characteristics are analyzed by coupling the Maxwell equations with the Navier-Stokes equation. The analysis algorithm also takes account of the effects of the thrust. The flow characteristics are analysed with the proposed method and compared with the commercial program and experiment and discussed.

The Analysis of Flow Characteristics of Conductive Liquid Metal Using TLIM Electromagnetic Pump (TLIM 전자펌프를 이용한 전도성 용융금속의 유동특성 해석)

  • Kim, Chang-Eob;Jeon, Mun-Ho;Kwon, Jeong-Tae;Lim, Hyo-Jae
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.12
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    • pp.130-141
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    • 2008
  • This paper presents the flow characteristics in the fluid circulation loop using the tubular type linear induction motor(TLIM) electromagnetic pump. A TLIM of thrust 40[N] is analyzed using the equivalent and genetic algorithm for the system The flow characteristics are analyzed by coupling the Maxwell equations with the Navier-Stokes equation with the thrust. The analysis algorithm is developed for analyzing the liquid metal flow in the system for laminar and turbulent flow. And the effect of thrust is analyzed for the flow characteristics.

Thermal Properties of Polyurethane Elastomers Prepared with MBCA/DMTDA Mixture as Curing Agent (MBCA/DMTDA 혼합경화제를 이용한 폴리우레탄 탄성체의 열적 성질)

  • Ahn, Won Sool
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.6
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    • pp.670-675
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    • 2016
  • Both melting temperature and enthalpy of MBCA/DMTDA mixtures were measured as a function of DMTDA compositions using DSC. The thermal properties of polyurethane elastomer samples prepared with MBCA, DMTDA, and 40/60 MBCA/DMTDA mixture as curing agents were also observed using TGA. MBCA and DMTDA showed good miscibility over the entire composition range, exhibiting individual DSC melting peaks. Peak temperatures were non-linearly reduced as DMTDA concentrations increased, being approximately $60^{\circ}C$ in the case of the 40/60 MBCA/DMTDA mixture. Furthermore, melting enthalpy of the mixture was calculated as 3.8 J/g, which was only 4.3% compared to 87.3 J/g of MBCA. Based on these results, crystallization of the mixture was considered to occur very slowly, and the fluidic gel-state of the mixture was visually confirmed to be maintained over 5 days at room temperature. Thermal decomposition of polyurethane elastomer prepared with 40/60 MBCA/DMTDA curative started at about $190^{\circ}C$, which is similar to that observed for DMTDA, only except decomposition behavior over higher temperature of $400^{\circ}C$.