• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.22-26
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• 1997

A small scale centrifugal oil separator consisted of two concentric tubes was fabricated for spilt oil recovery. With speed control of the inner tube, its performance of oil separation was investigated. Oil-water mixture is separated by forced vortex motion with the rotating inner tube. Velocity and pressure distributions in the tubes were calculated. Control of rotating speed, which is the most influencing parameter, showed an optimum value 946rpm corresponding to the acceleration of 20g at the inner tube surface. Separation performance was suddenly deteriorated at rotating speed higher than 1200rpm.

• Structural Engineering and Mechanics
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• v.67 no.5
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• pp.427-437
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• 2018

Structural pounding is commonly observed phenomenon during major ground motion, which can cause both structural and architectural damages. To reduce the amount of damage from pounding, the best and effective way is to increase the separation distance. Generally, existing design procedures for determining the separation distance between adjacent buildings subjected to structural pounding are based on approximations of the buildings' peak relative displacement. These procedures are based on unknown safety levels. The aim of this research is to estimate probabilistic separation distance between adjacent structures by considering the variability in the system and uncertainties in the earthquakes characteristics through comprehensive numerical simulations. A large number of models were generated using a robust Monte-Carlo simulation. In total, 6.54 million time-history analyses were performed over the adopted models using an ensemble of 25 ground motions as seismic input within OpenSees software. The results show that a gap size of 50%, 70% and 100% of the considered design code for the structural periods in the range of 0.1-0.5 s, leads to have the probability of pounding about 41.5%, 18% and 5.8%, respectively. Finally, based on the results, two equations are developed for probabilistic determination of needed structural separation distance.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.7-15
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• 2002

A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.127-140
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• 2007

We present the boundary value problem (BVP) for the heave motion due to a vertical circular cylinder in water of finite depth. The BVP is presented in terms of velocity potential function. The velocity potential is obtained by considering two regions, namely, interior region and exterior region. The solutions for these two regions are obtained by the method of separation of variables. The analytical expressions for the hydrodynamic coefficients are derived. Computational results are presented for various depth to radius and draft to radius ratios.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.615-624
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• 2016

In this study, two rectangular barges in close proximity were simulated to analyze the characteristics of motion responses due to hydrodynamic interactions. Using a numerical solution from DNV-GL SESAM, coupled stiffness matrix terms for these same FEM models were added to the multiple body modes in the surge direction. Potential theory was used to calculate the first order radiation and diffraction effects on the simulated barge models. In the results, the sheltering effect of the barges was not shown at 1.3 rad/s with hull separation of 20 m in transverse waves. The separation effect between the barges was more clear with longitudinal waves and a shallow water depth. However, sway forces were influenced by hull separation with transverse waves. The peaks for sway and heave motion and sway force occurred at higher frequencies as hull separation narrowed with longitudinal and transverse waves. Given a depth of 10 m, the sway motion on the lee side of a coupled barge made a significant difference in the range of 0.2-0.8 rad/s with transverse and oblique waves. Also, the peaks for sway force were situated at lower frequencies, even when incident waves changed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.539-549
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• 2017

In this paper, experimental studies on the shroud separation were performed to investigate characteristics of the shroud separation at mach 3. Shroud separation tests were carried out in the vertical free-jet wind tunnel that is capable of testing separable structures. A shroud model was miniaturized to meet test objectives and test section dimensions of the wind tunnel. Pneumatic Locking and separation mechanisms were designed considering external force due to free stream. High speed cameras were used to record the shroud motion and unsteady shock patterns over the deploying shrouds during the shroud separation process. Also, unsteady pressures on the nose surface were measured by using the pressure sensors. Through the tests, the measurement data necessary for researches on the shroud separation technology were obtained. Shroud separation behaviors and characteristics of unsteady pressure on the nose surface for each external flow conditions were analyzed.

• Journal of computational fluids engineering
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• v.13 no.4
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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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.31-37
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• 2015

Recently, mobile phones have become necessary tools for everyday life. In this study, a device that can serve as a separation between a touch panel and an LCD module in a mobile phone was devised for mass repair processes at a smaill business. We used a wire cutting method to separate the bonding plate area between the modules. The device is composed of DC motors and stepping motors that can deliver a precise cutting motion. The motor control system is connected by individual control modules to a CAN network. The developed device showed excellent performance at high temperature conditions.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.139-143
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• 2017

In this paper, we propose a separation method of the dielectric particles in the liquid flow. Since particles are dielectric in most cases, they experience dielectrophoretic(DEP) force under non-uniform electric field. The field characteristics in the electromagnetic and fluid dynamic systems are solved by using the finite element method. The motional equation of the particles is calculated by the Runge-Kutta method. The field analysis shows the feasibility of the proposed method. The particle separation model with large DEP force exerting on particles is designed by analyzing field characteristics.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.157-161
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• 2007

The prediction of the safe separation of the external stores carried on military aircraft is an important task in the aerodynamic design area having the objective to define the operational, release envelopes. The major concern of this study is only safe jettison problem with ejections. This work consists of concept and some results for external store configurations. A Computational Fluid Dynamics technique is applied to calculate the aerodynamic forces. The FLUENT with an implicit Euler solver is used for the present simulations. The computational results are validated against the experimental data.