• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.3
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• pp.94-99
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• 2009

In the Korean subway station, three types of pre-filters, which include auto filter, electrostatic precipitator (ESP) and auto cleaning demister, are widely used. However, these devices have some problems such as the difficulty of maintenance and high operating cost. In this study, axial-flow cyclone separator was employed as a pre-filter inside a heating, ventilation, and air conditioning (HVAC) system. 3-dimensional computational fluid dynamics (CFD) analysis was performed on a single unit axial-flow cyclone and coupled unit axial-flow cyclone. Calculated and measured pressure drop of the designed axial-flow cyclone were found be comparable to other types of pre-filters and the observed cut-off diameter was less than 10 micron. Considering lower operating and maintenance cost, axial-flow cyclone was proved to be a better solution as a pre-filter.

• Atmosphere
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• v.24 no.2
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• pp.207-223
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• 2014

The bogussing method was further developed by incorporating the asymmetric component into the symmetric bogus tropical cyclone of the Structure Adjustable Balanced Vortex (SABV). The asymmetric component is separated from the disturbance field associated with the tropical cyclone by establishing local polar coordinates whose center is the location of the tropical cyclone. The relative importance of wave components in azimuthal direction was evaluated, and only two or three wave components with large amplitude are added to the symmetric components. Using the Weather Research and Forecast model (WRF), initialized with the asymmetric bogus vortex, the track and central pressure of tropical cyclones were predicted. Nine tropical cyclones, which passed over Korean peninsula during 2010~2012 were selected to assess the effect of asymmetric components. Compared to the symmetric bogus tropical cyclone, the track forecast error was reduced by about 18.9% and 17.4% for 48 hours and 72 hours forecast, while the central pressure error was not improved significantly. The results suggest that the inclusion of asymmetric component is necessary to improve the track forecast of tropical cyclones.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.97-103
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• 2011

This study is numerical analysis on flow characteristic in a standard cyclone dust separator. The cyclone dust separator is widely used in a industrial applications as a method for dust removed from gases. In cyclone chamber, a very complex flow field is formed, involving the interaction between highly swirling velocity and turbulent field. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the working fluid that flow into cyclone dust separator. Helical entry type was increasing flow rate compared with tangent entry type. And according to increasing pressure difference was increased fan power. But, helical entry type was high performance dust separator, in comparison with tangent entry type.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.757-761
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• 2009

Axial-flow cyclone separator cluster can be used for a dust removal device inside a heating, ventilation, and air conditioning(HVAC) system of subway station. In this study, 3-dimensional computational fluid dynamics(CFD) analysis was performed to compare single unit axial-flow cyclone with couple unit axial-flow cyclone cluster. It is shown that the performance of cyclone separator is not influenced by number of single units but influenced by ability of single unit.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.111-125
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• 1996

A forecast technique using GMS-4(Geostationary Meteorological Satellite) infrared images and its $T_{BB}$ (Brightness Temperature) data to determine the tropical cyclone center and to analyze the tropical cyclone intensity has been developed. First, the determination of typhoon center using $T_{BB}$ distribution pattern is practiced by understanding a special feature of central cloud pattern and cloud band which is analyzed with the method of pseudo coloring. Then, to forecast the intensity of tropical cyclone, a relationship between the central pressure (or maximum wind speed) of tropical cyclone and $T_{BB}$ measured by GMS near the tropical cyclone center was investigated. The results showed a correlation with a high lag relationship between central pressures and $T_{BB}$. The mean Tee in the ring of 200~300km apart from the tropical cyclone center showed the best correlation to central pressure of the tropical cyclone after 24hour. From this relationship, a regression equation to forecast the central pressure (or maximum wind speed) was derived.

• Journal of the Korean Society of Visualization
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• v.16 no.2
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• pp.45-52
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• 2018

The tangential and axial cyclones were fabricated using a 3D printer and the total collecting efficiency, cut-diameter, and pressure drop characteristics of the two types of cyclones with the same inlet area were investigated experimentally. The results show that the total collecting efficiency tends to increase as the inlet velocity increases. However, at a 20m/s condition of the tangential cyclone, the collected particles were re-entrained to the ascending vortex flow, resulting in a decrease of the total collecting efficiency. In the axial cyclone, the cross-sectional area is designed to increase at the inlet and the velocity is reduced, so that the re-entrainment effect does not appear in this study. The pressure loss of the tangential cyclone was larger than that of the axial cyclone. The cut-diameter tends to decrease with increasing the inlet velocity in two types of cyclones, except for the 20m/s condition of the tangential cyclone.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.42-48
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• 2020

Given the increasing interest in air pollution, several technologies to measure black carbon (BC) aerosol particles have been developed. As most BC aerosol particles are smaller than 1 ㎛, it is necessary to pre-separate the particles by size before a BC measuring instrument samples the aerosol particles. In this study, a miniature cyclone separator for portable BC measuring instruments was developed. A numerical approach was used to design the miniature cyclone separator with operating flow rates of 50, 100, or 150 mLPM, and then a prototype cyclone separator was manufactured for experimental validation. The numerical results of the cut-off size and pressure drop of the miniature cyclone separator agreed well with the experimental data. The cut-off sizes of the miniature cyclone separator were determined to be 2.9, 0.94, and 0.63 ㎛ for operating flow rates of 50, 100, and 150 mLPM, respectively. Thus, the miniature cyclone separator is suitable for use as a sampling inlet for the portable black carbon measuring instrument to sample BC aerosol or PM2.5 aerosol.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E1
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• pp.21-28
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• 2003

An auxiliary device, called Post Cyclone (PoC). had been introduced and primarily examined in earlier works which proved the reduction of the emission of fine dust from the gas-solid cyclones without incurring significant increase of cost and pressure drop. It has been known that the PoC has some advantages over other secondary dust treatment devices such as (a) simple design, (b) low cost of manufacture, (c) minimum additional pressure drop, (d) high recoverbility of the product dust, and (e) simplicity of operation. Despite the potential advantage, however, lack of practical data confined its plausible application in wide areas. Thus, in this work, a few serial experiments were conducted in terms of a few operation conditions, and the particle trajectories throughout the cyclone set-up were visually analyzed by using a commercial computer simulation program (FLUENT).

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.390-391
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• 2003

Cyclone is one of the most widely used gas - solid separation devices in industries. In spite of its many advantages, lower separation efficiency and flat separation curve are usually associated with cyclones. Therefore, the primary goal of cyclone research is to improve its separation capability while retaining its basic features. In this study, granules were filled in the cone of a cyclone in an attempt to increase the cyclone separation efficiency through the combination of granular filtration and centrifugal separation. (omitted)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.485-492
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• 2013

The effect on collection efficiency with 2-stage vortex finder diameter and back mixing of solid flow due to swirling intensity, turbulence eddies, wall bouncing using the residence time distribution of particle flow in a common and modified cyclone. Higher collection efficiencies of fly ash in a modified cyclone(S = 13, 15cm) are showed than common cyclone. Collection efficiency in modified cyclone was highest at 2-stage vortex finder diameter, S = 13 cm. Variances of residence time distribution and average residence times of glass bead were increased with a diameter(S) of 2-stage vortex finder due to swirling intensity and turbulence eddies. Back mixing of solid flow in a modified cyclone were increased with a gas inlet velocity and showed higher than a common cyclone.