• 한국컴퓨터정보학회논문지
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• 제22권10호
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• pp.1-7
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• 2017

In this paper, the separation force measuring system is developed. The separation force aries due to adhesive strength between semiconductor epoxy molding compound(EMC) and the metal plate in semiconductor formed plate. In general, when removing the metal plate in semiconductor formed plate from semiconductor epoxy molding compound, excessive strength can result in a increase in semiconductor defect rates, or conversely, if too little force is exerted on the metal plate in semiconductor formed plate, the semiconductor production rates can decrease. In this study, the design criteria for the selection of the AC servo motor, the role of the ball screw, the relationship between the load cell and the ball screw, and the rate of deceleration are given. In addition, minimizing the reject rate of semiconductors and maximizing the semiconductor production rate are achieved through the standardization of the collected separation force data measured by the proposed system.

• 한국정밀공학회지
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• 제30권9호
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• pp.1001-1006
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• 2013

Projection-based stereolithography is divided into constrained-surface and free-surface type according to controlling liquid layer. The constrained-surface type has a uniform layer thickness due to the use of a projection window, which covers the pattern generator such as liquid crystal display. However, the adhered resin on the projection window causes trouble and requires great separation force when the cured layer is separated from the window. To minimize the separation force, we developed a system to measure the separation force. The influence of material covering the pattern generator and the resin temperature is investigated in the system. Several structures according to the resin temperature and the velocity of z-axis elevation are compared. As a result, the fabrication condition to minimize the separation force reduces the process time.

• International Journal of Aeronautical and Space Sciences
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• 제11권4호
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• pp.345-350
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• 2010

The repetitive vibrating action of an aerodynamic load causes an external fuel tank's horizontal fin to experience a shorter life cycle than its originally predicted one. Store separation analysis is needed to redesign the fin of an external fuel tank. In this research, free-drop tests were conducted using 15% scaled models in a subsonic wind tunnel in order to analyze the store separation characteristics of an external fuel tank. The store separation trajectory based on grid tests was also obtained to verify the results of the free-drop tests. The results acquired from the free-drop tests correlated well with the grid tests in regards to the trajectories and behavior of the stores separated from the aircraft. This agreement was especially noted in the early stages of the store separation.

• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.18-21
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• 2023

Pollution of the environment by micro-plastics is now a worldwide problem. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. In this paper, we aimed to experimentally demonstrate that micro-plastics in seawater can be continuously separated by electromagnetic Archimedes force. Using polyethylene particles of 3 mm in diameter as the separation target, a flow channel was fabricated and separation conditions were investigated by particle trajectory calculations for separation experiments. Based on the calculation results, a solenoid-type superconducting magnet was used as a source of magnetic field to conduct separation experiments of micro-plastics in seawater. Although a high separation rate was assumed in the simulation results, the experimental results did not show any significant improvement in the separation rate due to the electromagnetic Archimedes force. It was found that the gas generated by the electrolytic reaction may have inhibited the migration of the particles.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.315-319
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• 2009

Investigation of the lateral force fluctuations in an axisymmetric overexpanded compressed truncated perfect (CTP) nozzle for the shutdown transient is presented. These nozzles experience side-loads during start-up and shut-down operations, because of the flow separation at nozzle walls. Two types of flow separations such as free shock separation (FSS) and restricted shock separation (RSS) shock structure occur. A two-dimensional unsteady numerical simulation has been carried out over an axisymmetric CTP nozzle to simulate the lateral force fluctuations in nozzle during shutdown process. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved by coupled implicit scheme. Two equation k-$\omega$ SST turbulence model is selected. Unsteady pressure is measured at four locations along the nozzle wall. Present pressure variation compared well with the experimental data. During shutdown transient, separation pattern varies from FSS to RSS and finally returns to FSS. Several pressure peaks are observed during the RSS separation pattern. These pressure peaks generate lateral force or side loads in rocket nozzle.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.190-196
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• 2005

The power steering hose assembly is usually manufactured through the swaging process, which is conducted to connect a hose with metal fittings. In this process the hose is inserted into metal components, the sleeve and the nipple, and compressed in the radial direction by the jaws to clamp the hose with metal components. In case that the clamping force is small, the oil in the hose can leak locally under the severe operating conditions. To confirm the clamping force requirements, the measurement of separation force in longitudinal direction of the hose is usually performed. In this study, the swaging process of a hose is simulated with the finite element method, to investigate the effect of friction coefficient on the separation fDrce. The results interpretations are ffcused on the inner rubber component, and also a formula is proposed to estimate the separation farces with respect to friction coefficients.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2355-2364
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• 2018

We evaluated the effect of particle size and associated dynamics on a hydrocyclone separation process in order to understand the movement of the particle trajectories inside the hydrocyclone via numerical analysis, with particles of acid hydrolysis residues discharged in $TiO_2$ production via the sulfate method as a case study. The values obtained from the numerical simulation were successfully compared with those from experimental tests in the literature, allowing a description of the dynamics of the particles, their acting forces, and their relevant properties together with separation efficiency. The results showed that particle motion is jointly controlled by the drag force, the pressure gradient force and the centrifugal force. With increasing particle size, the influence of the drag force is weakened, whereas that of the centrifugal force and pressure gradient is strengthened. Factors including particle density, slurry viscosity, and inlet slurry flow rate also contribute to a clear and useful understanding of particle motion behavior in the hydrocyclone as a method for improving the separation efficiency.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1184-1189
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• 2018

Pyroprocessing uses various molten salts during electrochemical unit processes. Reaction products after the electrochemical processes must contain a significant amount of residual salts to be separated. Vacuum distillation is a common method to separate the residual salts; however, its high operation temperature may cause side reactions. In this study, a simple rotation technique using centrifugal force was suggested to separate the residual salts from the reaction products at relatively low temperature compared to the distillation technique. When a reaction product container with porous wall rotates inside a vessel heated above the melting point of the residual salt, the residual salt in the liquid phase is separated through centrifugal force. It was shown that the $LiNO_3-Al_2O_3$ mixture can be separated by this technique to leave solid $Al_2O_3$ inside the container, with a separation efficiency of 99.4%.

• 한국군사과학기술학회지
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• 제20권1호
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• pp.81-89
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• 2017

This study investigates store separation characteristics of an unmanned aerial vehicle having generic stealth configuration over unsteady flow of an internal bay. Free-drop wind tunnel tests are conducted to simulate bomb releases from an internal weapons bay while high-speed camera images are taken. The images are analyzed to examine the effects of flow velocity, angle of attack, flap deflection and the ejector force application on the store separation trajectories. For the free-drop wind tunnel tests, Froude Scaling is applied to match the dynamic similarity for the bomb model, and the ejector force is simulated by using small pneumatic cylinders. The results indicate that the test bomb model safely separates from the internal bay at the given test conditions and configurations. It is also observed that the effects of the flow velocity and ejector force application have greater impacts on the separation trajectories than those of angle of attack and flap deflection.

• 한국전산유체공학회지
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• 제13권4호
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• pp.80-85
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• 2008

The prediction of the separation trajectories of external stores released from a military aircraft is an important task in the aircraft design area having the objective to define the operational and release envelopes. This paper presents the results obtained for store separation by employing commercial softwares, FLUENT and CFD-FASTRAN. FLUENT treats the rigid body motion by employing a remeshing scheme. CFD-FASTRAN uses Chimera(overset) grid and interpolations. It was found that, for the prediction of the trajectories and behavior of the stores separated from the wing, both codes show the good agreement with the experimental results.