• Journal of Korea Water Resources Association
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• v.48 no.11
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• pp.879-889
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• 2015

The pattern of headward erosion at tributary and the separation zone formation in a loosed bed at confluence according to the confluence angle, discharge ratio, and dredging depth ratio have been analyzed. The separation zone is defined the inside of zero velocity boundary at downstream of confluence. The limit of separation zone occurrence is presented with dredging depth ratio. The propagation length of knickpoint increases as the confluence angle, discharge ratio, and dredging depth ratio increase in general and its regression equation has been suggested. The length and width ratios of separation zone in a loosed bed increase as discharge ratio and confluence angle increase as well as in a fixed bed. The length ratio decreases and the width ratio increases as dredging depth ratio increases results in great increase of shape factor and backwater rise by the conveyance reduction at confluence. The regression equation of shape factor with confluence angle, discharge ratio, and dredging depth ratio has been suggested.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.108.2-108.2
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• 2012

Recent results from microlensing surveys show that a free-floating planet or a wide-separation planet is more numerous than a main-sequence star in the Galaxy. Moreover, the detection efficiency of the planets will be improved in next-generation experiments with a high survey monitoring frequency. However, microlensing events produced by both planets appear similar light curves with a short duration timescale, thus it is difficult to distinguish them. In this paper, we investigated the detectable separation range of a wide-separation planet as the planet bound to its host star. We construct the fractional deviation maps using the magnifications of the planetary lensing and the single-lensing by planet itself for various parameters such as a mass ratio, separation, and source radius. As a result, we found that the pattern of the fractional deviation is related to the ratio of source radius to caustic size, and the ratio satisfying the detection criterion (i.e., ${\geq}5%$ in the fractional deviation) varies with a separation. Hence, we derived a fitting formula as the function of a mass ratio and a source radius to reflect the variation in the calculations of the detectable separation range of a wide-separation planet as the planet bound to its host star. In addition, we estimated the condition that a wide-separation planet can be detected as a single-lensing event under the finite source effect. We found that such a case is possible provided that the source radius is smaller than ~2.5 times of Einstein ring radius of a planet, regardless of a separation or a mass ratio.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.191-196
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• 2013

In this paper, the interaural intensity difference (IID)-based sounr source separation method in closely spaced stereo omnidirectional microphones is proposed. First, in order to improve the channel separability, a minimum variance distortionless response (MVDR) beamformer is employed to increase the intensity difference between stereo channels. After that, IID-based sound source separation method is applied. In order to evaluate the performance of the proposed method, source-to-distortion ratio (SDR), source-to-interference ratio (SIR), and sources-to-artifacts ratio (SAR), which are defined as objective evaluation criteria in stereo audio source separation evaluation campaign (SASSEC), are measured. As a result, it was shown from the objective evaluation that the proposed method outperforms a sound source separation method without applying a beamformer.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.169-175
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• 1998

The morphology of silk fibroin/poly(vinyl alcohol)(PVA)blend films was investigated using optical microscopy and confocal laser scanning microscopy. The effects of blend ratio and molecular weight of silk fibroin and PVA on phase separation were studied. Macro-phase separation occurred for the silk fibroin-rich/poor region whereas micro-phase separation took place for the dispersed/continuous phase, In spite of differences in molecular weight and blend ratio, it is observed that the dispersed phase and continuous one are composed of silk fibroin and PVA component, respectively. As the molecular weight of silk fibroin and silk fibroin content in blend ratio are decreased, the compatibility of blend is increased due to the reduction of micro-phase separation.

• Journal of the Korean Applied Science and Technology
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• v.41 no.1
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• pp.19-26
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• 2024

Recently, separation membranes have been applied to fields such as water supply, sewage treatment, gray water reuse, and air pollution control. Chemical cleaning technology is attracting attention among the methods of reusing these expensive separation membranes. It was found that the separation membrane could be regenerated using chemical cleaning. Specifically, it was found that the use time of the separation membranes regenerated by chemical cleaning was sustainable for more than 1,700 hours. Additionally, it was found that the flux recovery ratio after chemical cleaning was maintained at least 60%. In addition, the flux recovery ratio of HYDREX 4710, an organic membrane cleaner, and 4703, an inorganic membrane cleaner, was 76% and 62%, respectively, showing the highest flux recovery ratio among the chemicals used. Considering that the target raw water of this study is biological secondary treatment water, it was suggested that chemical cleaning could be actively used to regenerate separation membranes in future water treatment.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.242-250
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• 2017

Purpose: This study was conducted to determine the appropriate operating conditions through a factorial experiment for the secondary separating part of the self-propelled pepper harvester. Methods: An experimental setup that simulates the secondary separating part of the self-propelled pepper harvester was organized. Test samples were classified into three types according to the number of peppers on a stem, and 12 sets were prepared for each type. Among the operating conditions of the secondary separating part, the rotational speed of drum B (four levels), radial clearance between drums and cylindrical teeth (three levels), and speed ratio between the three drums (two levels) were set as the test factors, and tests were repeated three times for different levels of each factor. The appropriate operating conditions were determined by analyzing the separation ratio and damage ratio of the peppers collected through the secondary separating part. Results: The test factors changed the overall separation ratio and overall damage ratio in similar trends. In other words, the conditions that caused high overall separation ratios also exhibited high overall damage ratios. Owing to the high overall damage ratio in the condition with the highest overall separation ratio, the operating conditions should be selected considering both ratios. Conclusions: When the condition with more than 60% of overall separation ratio and less than 15% of overall damage ratio was considered as the appropriate operating condition, 70 rpm of the rotational speed of drum B, 5 mm of the radial clearance between drums and cylindrical teeth, and 7:3:5 for the speed ratio of the three drums A, B, and C should be applied for the secondary separating part used in this study. Supplementary studies will be required in the future to find optimal operating conditions through the actual field test under further divided test factors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.658-668
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• 1999

The objective of the present study is to investigate the effect of experimental parameters on the hydrodynamic characteristics in a horizontal tee-type evaporator using R-22. The experimental apparatus consisted of an unheated tee-type test section, a liquid-vapor separator, a preheated, mass flow meters, a plate heat exchanger, pump, and other measurement devices. The experimental parameters were mass flux(500 and 600kg/$m^2$s), inlet quality(0.1~0.3) and separation ratio(0.3~0.7). Absolute pressure at the inlet of the test section was 0.652 MPa. The branch-to-inlet inner diameter ratio was 0.61. Pressure gradient at the branch section was larger than that at the run section at the same separation ratio. Pressure drop per unit length increased at the run section and decreased at the branch section as the separation ratio increased. Pressure drop predicted by the separated flow model agreed with experimental data within -35 to +16%. Generally, predicted values showed similar trend with the data. Mass flow ratio of vapor refrigerant was affected by the inlet quality more than the mass flux.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.244-249
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• 2007

Fluidic conditions for the separation of phases were surveyed in a microfluidic aqueous two-phase extraction system. The infusion ratio between polyethylene glycol (PEG) and dextran solution defines the concentrations of each polymer in micro-channel, which determine the phase-separation. The appropriate ratio between PEG (M.W. 8000, 10%, w/v) and dextran T500 (M.W. 500000, 5%, w/v) in order to perform the separation of phases of both polymers was observed as changing the mixed ratio of both polymers. Based on the fluidic conditions, stable two-phase solutions were obtained within 4% to 8% and 3% to 1% of PEG and dextran, respectively. In addition, the characteristics of the two-phase were discussed. The separation technique studied in the paper can be applied for the implementation of a lab-on-a chip which can detect various biological entities such cells, bacterium, and virus in an integrated manner using built in a biosensor inside the chip.

• Journal of Mechanical Science and Technology
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• v.16 no.10
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• pp.1336-1345
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• 2002

A triboelectrostatic separation system using a fluidized bed tribocharger for the removal of PVC material in the mixture of PVC/PS plastics is designed and evaluated as a function of electric field strength, air flow rate, and the mixing ratio of two-component mixed plastics. It consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PS particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the electric Deld strength and particle mixing ratio. In the optimum conditions of 150 Ipm air flow rate and 2.6 kV/cm electric field strength a highly concentrated PVC (99.1%) can be recovered with a yield of more than 99.2% from the mixture of PVC and PS materials for a single stage of processing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.108-116
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• 2001

The vortex tube is a simple device which separates fluid stream into a cold stream and a hot stream without any chemical reaction. The process of energy separation in the vortex tube has caused a great deal of interest. Although many studies on energy separation in the vortex tube using air as the working fluid have been made so far, few experimental studies treated energy separation for incompressible fluid. So, an experimental study for the energy separation in the vortex tube using the water which is essentially an incompressible fluid is presented. When working fluid is the water, the best geometric values of nozzle area ratio and number of nozzle holes are 0.155, 6 respectively. These geometric values are showed by the similar values which are presented by compressible fluid as working fluid. But hot side mass fraction of which maximum temperature drop is happened are different from compressible fluid.