• 제목/요약/키워드: Heat Diffusion

검색결과 916건 처리시간 0.027초

액상확산접합용 인서트금속의 화학조성 최적화에 관한 연구 (A Study on the Optimum Chemical Composition of Insert Metal for Liquid Phase Diffuse Bonding)

  • 김대업;정승부;강정윤
    • Journal of Welding and Joining
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    • 제18권5호
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    • pp.90-97
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    • 2000
  • Effect of alloy elements on joinability of insert metal for liquid phase diffusion bonding of heat resistant alloys was investigated in this study. Also, optimum chemical composition of insert metal was explained using interpolation method. The insert metals utilized was commercial Ni-base amorphous foils and newly developed Ni-base filler metals with B, Si and Cr in this study. Melting point and critical interlayer width(CIW) decreased with increasing additional amount of B, Si and Cr, melting point lowering element of the insert metal. Optimized chemical composition of insert metals could be estimated by interpolation method. The optimum amount of B, Si, Cr addition into the insert metal were found to be about 3%, 4% and 3%, respectively. The measured characteristic values, melting point, microhardness in the bonded interlayer and CIW of the insert metals were the almost identical to ones of the calculated results by interpolation method.

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A Study on Heat Transfer and Film Growth Rate During the III-V MOCVD Processes

  • Ik Tae, Im;MASAKAZU, SUGIYAMA;VOSHIAKI, NAKANO;YUKIHIRO, SHIMOGAKI
    • 한국반도체및디스플레이장비학회:학술대회논문집
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    • 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
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    • pp.192-199
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    • 2003
  • Film growth of InP and GaAs using TMIn, TMGa, TBAs and TBP is numerically predicted and compared to the experimental results. To obtain exact thermal boundary conditions at the reactor walls, the gas flow and heat transfer are analyzed for full three-dimensional reactor including outer tube as well as the inner reactor parts. The results indicate that the exact thermal boundary conditions are important to get precise film growth rate prediction since film deposition is mainly controlled by the temperature dependent diffusion. The results also show that thermal diffusion plays an important role in the upstream region.

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전자제어식 직접분사 디젤 엔진 연소실내의 분무연소 특성에 관한 연구 (A study on the spray combustion characteristics in a cylinder of a D.I.diesel engine with the electronically controlled injector)

  • 정재우;김성중;이기형;선우명호
    • 한국자동차공학회논문집
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    • 제8권2호
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    • pp.50-56
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    • 2000
  • It is well known that the combustion phenomenon of diesel engine is an unsteady turbulent diffusion combustion. Therefore, the combustion performance of diesel engine is related to a complex phenomenon which involves the various factors of combustion, such as a injection pressure, injection timing, injection rate, and operation conditions of engine. In this study, the spray and the flame development processes in a single cylinder D.I. diesel visualization engine which uses the electronically controlled injection system were visualized to interpret the complicated combustion phenomenon by using high speed CCD camera. In addition, the cylinder pressure and heat release rate were also obtained in order to analyze the diesel combustion characteristics under several engine conditions.

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HPF 적용을 위한 극저탄소강의 강도에 미치는 침탄 열처리의 영향 (Strength Change in Ultra Low Carbon Steel due to Carburizing Heat Treatment for Hot Press Forming)

  • 강수영
    • 대한금속재료학회지
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    • 제50권6호
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    • pp.433-438
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    • 2012
  • Strength change in ultra low carbon steel carburized at $880^{\circ}C$ and $930^{\circ}C$ for 10, 30, 60 and 120 minutes was investigated. The results were analyzed by a tensile test, chemical composition analysis, optical microscopy and scanning electron microscopy. Stress in the 0.5% strain specimen in the tensile test increased as the time treated at $880^{\circ}C$ and $930^{\circ}C$ increased, because the carbon diffusion layer and the martensite of the specimen increased with increasing treatment time. Martensite was found in the ferrite region in the specimen treated at $880^{\circ}C$, which is attributed to grain boundary diffusion.

물성치 모델개발을 통한 고강도콘크리트의 시간의존 해석 (Time-dependent Analysis of High Strength Concrete Using Material Characteristics Model)

  • 이태규;김혜욱
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2008년도 추계학술대회 논문집
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    • pp.1096-1101
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    • 2008
  • Concrete is shown the time dependent behavior after placing. The time dependent behavior of normal strength concrete that is used usually in present, were already examined closely lots of parameters by several investigators. however, high strength concrete is that the material characteristics are not definite and the experimental data are lacking. So, The goal of this study is to propose the material characteristics models, and to develop the routine of the time dependent behavior above 60 MPa. The thermal conductivity, the specific heat, the moisture diffusion coefficient, and the surface coefficient are proposed the suitable models through the parametric study. The structural element is used the 8-node solid element. The matrix equation is developed considering the transient heat transfer and moisture diffusion theory. The application of the time dependent behavior is used the finite differential method.

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이산화탄소가 수소 산소부화 화염의 열전달에 미치는 영향 (Effects of CO2 on Heat Transfer from Oxygen-Enriched Hydrogen Flame)

  • 이창엽;최준원;백승욱
    • 대한기계학회논문집B
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    • 제28권8호
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    • pp.937-944
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    • 2004
  • An experimental study has been conducted to evaluate the effects of $CO_2$ on heat transfer from oxygen-enriched hydrogen flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which was mounted on top of the furnace. Five different oxidizer compositions were prepared by replacing $N_2$ with $CO_2$. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace have been measured using a heat flux meter. Temperature distribution in furnace also has been measured and compared. By increasing $CO_2$ proportion in the oxidizer, the convection played a more significant role rather than radiation. Overall temperature in the furnace was seen to be decreased, while the total heat flux has increased.

LOCAL APPROXIMATE SOLUTIONS OF A CLASS OF NONLINEAR DIFFUSION POPULATION MODELS

  • Yang, Guangchong;Chen, Xia;Xiao, Lan
    • Nonlinear Functional Analysis and Applications
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    • 제26권1호
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    • pp.83-92
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    • 2021
  • This paper studies approximate solutions for a class of nonlinear diffusion population models. Our methods are to use the fundamental solution of heat equations to construct integral forms of the models and the well-known Banach compression map theorem to prove the existence of positive solutions of integral equations. Non-steady-state local approximate solutions for suitable harvest functions are obtained by utilizing the approximation theorem of multivariate continuous functions.

저신장율 대향류확산화염에서 에지화염 불안정성에 관한 열손실 효과 (Effects of Heat Losses on Edge-flame Instabilities in Low Strain Rate Counterflow Diffusion Flames)

  • 박준성;황동진;김정수;길상인;김태권;박정
    • 대한기계학회논문집B
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    • 제30권10호
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    • pp.996-1002
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    • 2006
  • Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Critical mole fraction at flame extinction is examined with velocity ratio and global strain rate. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate and added nitrogen mole fraction to fuel stream (fuel Lewis number). It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations in low strain rate flames are experimentally described well and are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames. Important contribution of lateral heat loss even to edge flame oscillation is clarified