• Design & Manufacturing
• /
• v.9 no.1
• /
• pp.1-4
• /
• 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.

• Journal of Welding and Joining
• /
• v.21 no.6
• /
• pp.46-54
• /
• 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.

• Nuclear Engineering and Technology
• /
• v.42 no.3
• /
• pp.297-304
• /
• 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.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.7
• /
• pp.22-30
• /
• 2009

• Journal of ILASS-Korea
• /
• v.22 no.2
• /
• pp.87-95
• /
• 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.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.6
• /
• pp.75-80
• /
• 2013

In this study, a forced ignition method with a plasma jet torch is studied in Mach 2 laboratory scaled wind-tunnel. The hyper-mixer is used as a mixer. For two normal injection cases, the one is collided against a wedge plate of the hyper-mixer and the other is directly injected into the cold main flow. For the first case, the hyper-mixer disperses the injected fuel, leading to the mixing enhancement. Furthermore, the fuel-air mixture is provided into the plasma hot gas, which enhances the combustion performance. However, the direct injection into the main flow method spends amount of fuel without ignition in the cold supersonic flow. In the end, for the forced combustion, it is important to supply the fuel-air mixture into the heat source.

• Journal of Biomedical Engineering Research
• /
• v.27 no.5
• /
• pp.267-273
• /
• 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.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.1
• /
• pp.25-31
• /
• 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.

• 한국연소학회:학술대회논문집
• /
• 2006.10a
• /
• pp.27-35
• /
• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.4
• /
• pp.552-558
• /
• 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.