• Journal of Aquaculture
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• v.18 no.3
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• pp.180-188
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• 2005

The separation performances for thirty different dimensions of a low-pressure hydrocyclone (LPH) were tested in order to obtain an optimum dimension scale for fecal solid removal from an aquaculture system. The geometric variables were considered on two inlet diameters (Di: 30 and 50 mm), five overflow diameters (Do: 30, 50, 60, 70 and 100 mm), and three cylinder lengths (Lc: 250, 345 and 442 mm), while the cylinder diameter (Dc) of 335 mm, underflow diameter (Du) of 50 mm and cone angle (${\theta}$) of $68^{\circ}$ were kept constant. A small size for carp feces was regarded as the target for the removal of solids. Spherical polystyrene particles (1.1-1.3 mm dia., ${\rho}_s=1.05g/cm^3$), which demonstrate a similar settling velocity and specific gravity to the carp feces, were used as feed. The separation performance was tested in the range of 330 to 1200 ml/s of the inflow rate. Experimental results using ANCOVA and the Tukey test (${\alpha}=0.05$) demonstrated that the separation performances of LPH were significantly affected (P<0.05) by fi, Di and Do. In contrast, there was no significant Lc effect (P>0.05) on the separation performances. The maximum separation performance was detected at dimension combinations of 30 mm of inflow diameter (Di), 50, 60 and 70 mm of overflow diameter (Do), 345 mm of cylinder length (Lc). The dimension proportions were 0.09, 1.03, 0.15-0.21 and 0.15 (or Di/Dc, Lc/Dc, Do/Dc and Du/Dc, respectively.

• Journal of Aquaculture
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• v.18 no.3
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• pp.189-195
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• 2005

By testing the separation performance for a fine settleable solid removal system in an aquaculture system using polystyrene particles as an experimental substitute, the optimal geometric dimensions for a Low-Pressure Hydrocyclone (LPH) were obtained. The design approach far the LPH took into consideration two inflow diameters (Di: 30, 50 mm), three overflow diameters (Do: 60, 70, 100 mm) and four cylinder lengths (Lc: 250, 345, 442, 575 mm), while the cylinder diameter (Dc) at 335 mm, the underflow diameter (Du) at 50 mm and the cone angle (${\theta}$) at $68^{\circ}$ were kept constant. The separation performances of 19 different dimension combinations of LPH were tested, ranging from 300 to 1200 ml/sec of inflow rate using substitute polystyrene particles (0.4-0.7 mm dia., ${\rho}_s=1.05g/cm^3$). These polystyrene particles exhibit a similar density and settling velocity to the fine fecal debris of the common carp. The total separation efficiency for the inflow rate ranged from a high of 97% to a low of 20%. Experimental results obtained by ANCOVA and the Tukey test (${\alpha}=0.05$) showed that the separation performances of the LPH were significantly affected (P<0.05) by the fi, Di, Do and Lc. The maximum separation performance was detected at a dimension combination of 30 mm of inflow diameter (Di), 60 mm of overflow diameter (Do), 442 and 575 mm of cylinder length (Lc). The dimension proportions were 0.09, 1.32-1.72, 0.18 and 0.15 for Di/Dc, Lc/Dc, Do/Dc and Du/Dc respectively.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.150-156
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• 2010

The separation performance of a low-pressure hydrocyclone (LPH) was evaluated for suspended-solids removal in a recirculating aquaculture system (RAS). The dimensions of the LPH were 335 mm cylinder diameter, 575 mm cylinder height, 60 mm overflow diameter, 50 mm underflow diameter, and $68^{\circ}$ cone angle. The inflow rate varied (400, 600, 800, and 1,000 mL $s^{-1}$) with 25%, 25%, 20%, and 10% of bypass ($R_f$), respectively. The maximum total separation efficiency (Et) and reduced separation efficiency (E't) for suspended solids from the effluent of the second settlement tank (before biofiltration) were 58.9% and 45.2%, respectively, at an inflow rate of 600 mL $s^{-1}$ and 25% of $R_f$. The maximum Et and E't for suspended solids from the water supply channel (after biofiltration) were 24.4% and 16%, respectively, at an inflow rate of 1,000 mL $s^{-1}$ and 10% of $R_f$. The maximum grade efficiency (Ei) was 51.6% for a 300 ${\mu}m$ particle size at an inflow rate of 600 mL $s^{-1}$ with 23% of $R_f$. The maximum reduced grade efficiency (E'i) was 37.6% for a 300 ${\mu}m$ particle size at an inflow rate of 1,000 mL $s^{-1}$ with 11% of $R_f$. The results indicate that the separation performance of the LPH for suspended solids removal was size selective and that maximum removal occurred at particle sizes ranging from 300 to 500 ${\mu}m$.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.218-219
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• 2008

A gas-liquid centrifugal separator is widely used in industry because of its simple geometry and little maintenance. Also, these separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, low pressure drop and higher capacity. A gas-liquid centrifugal separator is a device that utilizes centrifugal force and low pressure to separate liquid from gas by density difference. Design parameters such as length of separation space, swirl vane exit angle, inlet to outlet pipe diameter ratio, models for separation efficiency and low pressure drop as a function of physical dimension are not available in literature. In present study, length of separation space (from vane to gas exit opening) has been studied using CFD. The 3-D Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Based upon the obtained solutions, tangential velocities, centrifugal forces, vortices and total pressure losses are analyzed to find the best design parameters.

• Wind and Structures
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• v.5 no.1
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• pp.25-48
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• 2002

Wind flow and pressure on the roof of the Texas Tech Experimental Building are studied along with the incident wind in an effort to understand the wind-structure interaction and the mechanisms of roof pressure generation. Two distinct flow phenomena, cornering vortices and separation bubble, are investigated. It is found for the cornering vortices that the incident wind angle that favors formation of strong vortices is bounded in a range of approximately 50 degrees symmetrical about the roof-corner bisector. Peak pressures on the roof corner are produced by wind gusts approaching at wind angles conducive to strong vortex formation. A simple analytical model is established to predict fluctuating pressure coefficients on the leading roof corner from the knowledge of the mean pressure coefficients and the incident wind. For the separation bubble situation, the mean structure of the separation bubble is established. The role of incident wind turbulence in pressure-generation mechanisms for the two flow phenomena is better understood.

• The Journal of the Acoustical Society of Korea
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• v.31 no.5
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• pp.332-339
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• 2012

Beamspace transform algorithm transforms spatial-domain data - such as x, y, z dimension - into incidence-angle-domain data, which is called beamspace-domain data. The beamspace transform method is generally used in source localization and tracking, and adaptive beamforming problem. When the beamspace transform method is used in multichannel audio source separation, the inverse beamspace transform is also important because the source image have to be reconstructed. This paper studies the beamspace transform and inverse transform algorithms for multichannel audio source separation system, especially for the beamspace-domain multichannel NMF algorithm.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.416-424
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• 2018

Oil spill and oily wastewater have now become a serious threat to the freshwater and marine environments. Porous materials with super-hydrophobicity and super-oleophilicity are good candidates for the oil adsorption and oil/water separation. Here, flexible hybrid nanofibrous membrane (FHNM) containing $SiO_2$/polyvinylidene fluoride (PVDF) microspheres was prepared by simultaneous electrospinning and electrospraying. The obtained FHNM combined the flexibility of the nanofiber mat and super-hydrophobicity of the microspheres, which could not be achieved by either only electrospinning or only electrospraying. It was found that when the weight ratio between the $SiO_2$ and PVDF reached a critical value, the $SiO_2$ nanoparticles were present on the PVDF microsphere surface, significantly improving the surface roughness and hence the contact angle of the FHNM. Compared with the pure electrospun PVDF nanofiber mat, most of the FHNMs have a higher oil adsorption capacity. The FHNM could separate the oil with water quickly under the gravity and displayed a high efficiency and good reusability for the oil/water separation. More importantly, the FHNM could not only separate the oil with the pure water but also the corrosive solution including the salt, acid and alkali solution.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.1-6
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• 2013

Numerical optimization of two dimensional high lift configuration was performed with flow solver and optimization method based on RSM(Response Surface Model). Navier-Stokes solver with Spalart-Allmaras turbulence model was selected for the simulation of highly complex and separated flows on the flap. For the simultaneous optimization of both flap shape and setting (gap/overlap), 10 design variables (eight variables for flap shape variation and two variables for flap setting) were chosen. In order to generate the response surface model, 128 experimental points were selected for 10 design variables. The objective function considering maximum lift coefficient, lift to drag ratio and lift coefficient at specific angle of attack was selected to reduce flow separation on the flap surface. The present method was applied to two dimensional fowler flap in landing configuration. After applying the present method, it was shown that the optimized high lift configuration had less flow separation on the flap surface and lift to drag ratio was suppressed over entire angle of attack range.

• Macromolecular Research
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• v.15 no.6
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• pp.553-559
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• 2007

Nanocomposite films were prepared by sol-gel synthesis from vanadium triisopropoxide with $poly((oxyethylene)_9$ methacrylate)-graft-poly(dimethyl siloxane), POEM-g-PDMS, producing in situ growth of vanadium oxide within the continuous ion-conducting POEM domains of micro phase-separated graft copolymer. The formation of vanadium oxide was confirmed by wide angle x-ray scattering (WAXS) and Fourier transform infrared (FT-IR) spectroscopy. Small angle x-ray scattering (SAXS) revealed the spatially-selective incorporation of vanadium oxide in the POEM domains. Upon the incorporation of vanadium oxide, the domain periodicity of the graft copolymer monotonously increased from 17.2 to 21.0 nm at a vanadium content 14 v%, above which it remained almost invariant. The selective interaction of vanadium oxide with POEM was further verified by differential scanning calorimetry (DSC) and FT-IR spectroscopy. The nanocomposite films exhibited excellent mechanical properties $(l0^{-5}-10^{-7}dyne/cm^2)$, mostly due to the confinement of vanadium oxide in the POEM chains as well as the interfaces created by the microphase separation of the graft copolymer.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.907-915
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• 2009

Spectrum sharing between wireless systems becomes a critical issue due to emerging new technologies and spectrum shortage. Recently, IMT system has been allocated in the same frequency C band (3400-4200MHz) along with FSS services on co-primary basis, which means that harmful interference probability may be inspired. In this paper, to estimate the spectrum sharing between IMT and FSS systems, the minimum separation distances have been evaluated considering major factors such as the clutter loss in some areas and the elevation angle of FSS earth station, and using I/N=-10dB which is fundamental criterion for coexistence.