• 제목/요약/키워드: Forced Injection

검색결과 53건 처리시간 0.027초

언더컷 처리장치 없는 사출성형을 위한 강제취출에 관한 연구 (A Study on the forced ejecting for injection molding without undercut processing unit)

  • 이희철;이희진;김경호;황재영;김영식;류호연
    • Design & Manufacturing
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    • 제9권1호
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    • pp.1-4
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    • 2015
  • Recently, the mold industry has been developed to high-quality and high-productivity with various demands of the high-tech industry. Also, geometry parts of injection mold are complex and diverse optimum design through the injection molding analysis has become a matter of course. The mold industry is trying to revitalize the industry with demand technology development and manufacturing process improvement. However, products that have undercut is the need for a separate processing mechanism and structure of the mold is getting more complex, the cost is expensive. Therefore, improving the structure of the mold through a study on the forced ejecting for injection molding without undercut processing unit and to improve the productivity.

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강제대류-적외선 리플로 솔더링시 전자조립품의 열적반응 분석 (Analysis on the Thermal Response of Electronic Assemblies during Forced Convection-Infrared Reflow Soldering)

  • 손영석;신지영
    • Journal of Welding and Joining
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    • 제21권6호
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    • pp.46-54
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    • 2003
  • The thermal response of electronic assemblies during forced convection-infrared reflow soldering is studied. Soldering for attaching electronic components to printed circuit boards is performed in a process oven that is equipped with porous panel heaters, through which air is injected in order to dampen temperature fluctuations in the oven which can be established by thermal buoyancy forces. Forced convection-infrared reflow soldering process with air injection is simulated using a 2-dimensional numerical model. The multimode heat transfer within the reflow oven as well as within the electronic assembly is simulated. Parametric study is also performed to study the effects of various conditions such as conveyor speed, blowing velocity, and electronic assembly emissivity on the thermal response of electronic assemblies. The results of this study can be used in the process oven design and selecting the oven operating conditions to ensure proper solder melting and solidification.

ENHANCEMENT OF DRYOUT HEAT FLUX IN A DEBRIS BED BY FORCED COOLANT FLOW FROM BELOW

  • Bang, Kwang-Hyun;Kim, Jong-Myung
    • Nuclear Engineering and Technology
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    • 제42권3호
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    • pp.297-304
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    • 2010
  • In the design of advanced light water reactors (ALWRs) and in the safety assessment of currently operating nuclear power plants, it is necessary to evaluate the possibility of experiencing a degraded core accident and to develop innovative safety technologies in order to assure long-term debris cooling. The objective of this experimental study is to investigate the enhancement factors of dryout heat flux in debris beds by coolant injection from below. The experimental facility consists mainly of an induction heater, a double-wall quartz-tube test section containing a steel-particle bed and coolant injection and recovery condensing loop. A fairly uniform heating of the particle bed was achieved in the radial direction and the axial variation was within 20%. This paper reports the experimental data for 3.2 mm and 4.8 mm particle beds with a 300 mm bed height. The dryout heat density data were obtained for both the top-flooding and the forced coolant injection from below with an injection mass flux of up to $1.5\;kg/m^2s$. The dryout heat density increased as the rate of coolant injection increased. At a coolant injection mass flux of $1.0\;kg/m^2s$, the dryout heat density was ${\sim}6.5\;MW/m^3$ for the 4.8 mm particle bed and ${\sim}5.6\;MW/m^3$ for the 3.2 mm particle bed. The enhancement factors of the dryout heat density were 1.6-1.8.

DPF 재생을 위한 연료 후분사 전략에 대한 연구 (Research on Post Injection for Diesel Particulate Filter Regeneration)

  • 최민후;윤성준;박성욱
    • 한국분무공학회지
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    • 제22권2호
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    • pp.87-95
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    • 2017
  • Recently, as the interest in environmental issues have increased around the world, the regulation on vehicle exhaust have been tightened in each country. To satisfy such tightened exhaust regulation, automotive manufactures are forced to equipped Diesel Particulate Filter (DPF) at Diesel vehicles. If DPF is used for a long time, DPF regeneration should be performed. The objective of this study is to research on post injection for DPF regeneration. The result of the study was that it was desired that retarding post injection timing, lower load of engine and smaller the amount of main fuel injection, for DPF regeneration. Oil dilution was tended to increase as load was lower, amount of post injection was increased, and post injection timing was retarded.

하이퍼 혼합기를 사용한 저엔탈피 초음속 유동장 내연소 특성 연구 (Combustion Characteristics Study using Hyper-mixer in Low-enthalpy Supersonic Flow)

  • 김채형;정인석
    • 한국추진공학회지
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    • 제17권6호
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    • pp.75-80
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    • 2013
  • 본 연구에서는 마하 2의 실험실 규모의 풍동장치에서 플라즈마 제트 토치를 점화기로 사용하여 강제점화에 대한 연소 특성을 연구하였다. 하이퍼 혼합기는 혼합기로 사용되었다. 수직분사의 경우, 하나는 하이퍼 혼합기의 웨지면에 충돌하도록 하였으며, 다른 하나는 차가운 주유동으로 바로 분사되도록 하였다. 하이퍼 혼합기와 충돌하는 경우 충돌된 연료는 분산되며 확산 혼합에 의해 혼합성능이 증대된다. 또한 혼합된 가스는 대부분 플라즈마 제트의 열원으로 유입되어 연소 성능을 증대시킨다. 하지만 주유동으로 직접 분사되는 경우는 초음속의 주유동 내에서 점화되지 못하고 많은 양의 연료가 소비된다. 따라서 강제점화방식의 연소의 경우에는 많은 양의 연료-공기 혼합물을 점화가 가능한 열원으로 공급하는 것이 중요하다.

The Effect of Urokinase Infusion Regimens on Thrombolysis - a Numerical Study

  • Jeong, Woo-Won;Jang, An-Sik;Rhee, Kye-Han
    • 대한의용생체공학회:의공학회지
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    • 제27권5호
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    • pp.267-273
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    • 2006
  • Numerical analysis was performed on the enzyme transport and the flow fields in order to predict the effectiveness of urokinase injection regimens in clot dissolution. The species and momentum transport equations were numerically solved for the case of uniform perfusion of enzyme into a fibrin clot for an arterial thrombus and a deep vein thrombus models. In order to predict the thrombus lysis efficiency of continuous and forced intermittent injections, enzyme perfusion and clot lysis were simulated for the different injection velocities. Intermittent injection showed faster clot lysis compared to continuous perfusion, and lysis efficiency was increased as injection velocity increased.

광디스크 드라이브의 입자 오염 및 열축적 제어를 위한 설계 제안 (Control of Particle Contamination and Heat Build-Up for Noble Design of an Optical Disk Drive)

  • 오서영;황정호
    • 대한기계학회논문집B
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    • 제27권1호
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    • pp.25-31
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    • 2003
  • Airborne contaminant particles are intruded into optical disk drives(ODD) due to the flow caused by disk rotation and can be adhered to lens or disk surfaces, which causes decrease of laser power and increase of read/write errors. Such a phenomenon can be more serious as the space between the disk and the lens is reduced fur high-density storage devices. The purpose of this paper is to understand design parameters to reduce the particle intrusion into an ODD. Suggestions are made to prevent the particle intrusion that can decrease the stability of an ODD and also prevent the potential heat build-up problem. The sealing effect of drive and the forced injection of clean air (using HEPA filter) into the drive minimizes intrusion of the outside air and dusts in an ODD remarkably. Moreover it is proved by experiments that the installation of a heatproof pad to isolate heat generation part (PCB) from information read/write sections and the forced injection of dust-free air reduce the gas temperature inside the drive as well as the amount of particles intruded.

연소실내의 압력 변동에 따른 연료 분사구에서의 당량비 변동에 관한 수치해석 (Numerical Simulation on Equivalence Ratio Fluctuation at the Fuel Injection Hole with respect to Pressure Fluctuation in a Combustion Chamber)

  • 김현준;홍정구;신현동
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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    • pp.27-35
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    • 2006
  • It has been observed in experiments that combustion instability of low frequency (${\sim}$ 10Hz) results form the modulation of equivalence ratio at fuel injection hole when a pressure fluctuation propagates upwards along the channel of the burner under an unchoked fuel flow condition. In this study, a commercial program was used to determine how the fuel flow rate changed with respect to the pressure, velocity of the fuel flow and the mass fraction in a choked and an unchoked condition. The calculation focus on the upstream of the dump plane to know how the forced pressure with the fuel injection conditions affects the modulation of the equivalence ratio. Therefore, it is found that pressure fluctuation leads to oscillation of mass flow rate and then results in equivalence ratio modulation under the unchoked fuel flow condition.

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일정 열유속의 열원을 갖는 사각공간의 혼합대류 열전달 (Heat transfer of Mixed convection in rectangular space with constant heat flux)

  • 조대환
    • Journal of Advanced Marine Engineering and Technology
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    • 제23권4호
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    • pp.552-558
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    • 1999
  • Ventilation of the marine engine room is very important for the health of the workers as well as the normal operation of machines. To find proper ventilation conditions of this engine room numerical simulation with a standard k-$\varepsilon$model was carried out. In the present study the marine engine room is considered as a closed space with a heat source and forced ventilation ducts. The injection angle of air supply is found to be important. Injection with a downward angle depresses recirculation flow causing a strong stream in the wider space of the room Ventilation and removal of the released heat are promoted with this pattern, There is a possibility of local extreme heating at the upper surface of the engine when supply and exhaust ports of air are in bilateral symmetry.

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