• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.237-250
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• 1998

In this study, the characteristics of electrostatic bag filter to overcome the main problems such as the high pressure drop and low collection efficiency for submicron particles are investigated with the experimental parameters. Especially, the experiment is carried out focusing on collection efficiency and pressure drop change mechanism as a function of discharge electrode shapes and filter properties, including the applied voltages, filtration velocities and particle concentrations, etc . Results show that the collection efficiency is improved over 30% for the fine particle below 1 pm and pressure drop reduction ratio (PDRR) increases in the following order 4 mm screwy > 4 mm square > 4mm round discharge electrodes . For the filter properties, Nomex is more effective than PE under the influence of electrostatic force. Applying 30 kV for a screwy discharge electrode, higher overall collection efficiency is maintained in spite of the increment of filtration velocity over four times (8 m/min) in comparison with that of 2 m/min and PDRR are highly shown over 80o1o with various filtration velocities, 5, 8, 11 m/min.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.121.1-121.1
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• 2014

Recently, much attention has been given to plasma production under liquid and its applications [1]. However, most of plasma production techniques reported so far utilize high voltage dc, ac, rf or microwave power [2], where damage to discharge electrodes and small discharge volume are remained issues. As an alternative of plasma production method under liquid, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. We have also reported improvement of treatment efficiency with use of reduced-pressure condition during the discharge [3]. To realize low pressure conditions in liquid, various alternative technique can be considered. One possible technique is simultaneous injection of microwave power and ultrasonic wave. Ultrasonic wave induces pressure fluctuation with the wave propagation and is so far used for cavitation production in the water. We propose utilization of reduced pressure induced by ultrasonic cavitation for improvement of the plasma production. Correlation between the plasma production and the ultrasonic power will be discussed.

• Journal of ILASS-Korea
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• v.27 no.1
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• pp.42-49
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• 2022

Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.2
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• pp.185-190
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• 1995

Recently, because of the worse of the air pollution, the excessive airtught of building and the inferiority of air conditioning system, the development of high efficiency air purification technology was enlarged to the environmental improvement of an indoor or a harmful working condition. The air purification technology has used chemical filters or charcoal filters or charcoal to remove hazardouse gaseous pollutants (SO$_{x}$, NO$_{x}$, NH$_{3}$, etc.) by air pollutant control technology, but they have many problems of high pressure loss, short life, wide space possession, and treatment of secondary wastes. For these reason, the object of reasearch shall be hazardous gaseous pollutants removal by the surface discharge induced plasma chemical process that is A.C. discharge of multistreams applied A.C. voltage and frequency between plane induced eletrode and line discharge eletrode of tungsten, platinum or titanium with a high purified alumina sheet having a film-like plane. As a result, the control performance for hazardous gaseous pollutants showed very high efficiency in the normal temperature and pressure. Also, after comtact oxidation decomposition of harmful gaseous pollutants, the remainded ozone concentration was found much lower than that of ACGIH or air pollution criteria in Korea.rea.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.1
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• pp.29-35
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• 1987

TPolystyrene thin films are prepared by glow discharge of sytrene monomer vapor th establish the growth mechanism of organic thin films by the plasma polymerization. As the discharge parameters, discharge current(5mA-20mA), frequency (10kHz-50kHz, 13.56MHz), gaspressure (0.2torr-1.5torr), and discharge time(2min-12min)are adopted. Plasma-polymerized filmsof styrene vapor are identified as polystyrene by IR spectra. The thickness of plasma-polymerized films increases with gas pressure, frequency and discharge current in the region of the low frequency and below the allowed gas pressure where the polymerization occurs. It is suggested that the growth mechanism can be explained by ionic reaction in d.c. and low frequency region, and by radical reaction in high frequency region.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.74-78
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• 2017

The discharge characteristics of the radio frequency (RF) surface dielectric barrier discharge have been simulated for the investigation of the ratio of the ion transit time to the RF period. From one-dimensional particle-in-cell (PIC) simulation for a planar dielectric barrier discharge (DBD), it was observed that the high-frequency driving voltage confines the ions in the plasma because of a shorter RF period than the ion transit time. For two-dimensional surface dielectric barrier discharges, a fluid simulation is performed to investigate the characteristics of RF discharges from 1 MHz to 40 MHz. The ratio of the peak density to the average density decreases with the increasing frequency, and the spatiotemporal discharge patterns change abruptly with the change in the ratio of ion transit time to the RF period.

• Journal of Surface Science and Engineering
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• v.36 no.5
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• pp.357-363
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• 2003

The aim of this work is the synthesis of a-C:H films from methane gas using surface spark discharge at the atmospheric pressure. Properties of these films have been investigated as functions of energy W delivered per a methane molecule in the discharge. The method enables the coatings to be deposited with high growth rates (up to $100 \mu\textrm{m}$/hour) onto large-area substrates. It is shown that the films consist of spherical granules with diameter of 20∼50 nm formed in the spark channel and then deposited onto the substrate. The best film characteristics such as minimum hydrogen-to-carbon atoms ratio H/C=0.69, maximum hardness $H_{v}$ =3 ㎬, the most dense packing of the granules and highest scratch resistance has been obtained under the condition of highest energy W of 40 eV. The deposited a-C:H coatings were found to be more soft and hydrogenated compared to the diamond-like hydrogenated (a-C:H) films which obtained by traditional plasmaenhanced chemical vapor deposition methods at low pressure (＜10 Torr). Nevertheless, these coatings can be potentially used for scratch protection of soft plastic materials since they are of an order harder than plastics but still transparent (the absorption coefficient is about $10^4$∼$10^{5}$ $m^{-1}$ At the same time the proposed method for fast deposition of a-C:H films makes this process less expensive compared to the conventional techniques. This advantage can widen the application field of. these films substantially.y.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.275-284
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• 1998

Standard on the carbon dioxide extinguishing system was prepared by the committed of the national fire protection assocition(NFPA)in USA on 1980. And this code is also applied to the design of a marine fire extinguishing system The most important problem in design is the uniform discharge of $CO_2$ through each nozzle from the high pressure $CO_2$ storage facility. The purpose of this paper is to develop the computer software to design the marine fire protection piping system. By solving the continuity equation energy equation and Bernoulli's equation simulataneously the flowrate in branch pipelines and discharge nozzles can be calculated.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.675-678
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• 2006

We developed a Flat Fluorescent Lamp(FFL) with a high luminance by using the same discharge mode as PDP. Our FFL has the simple and unique structure where the glass substrates are used as dielectric layers. The panel has a striped line shape of 7 inch diagonal size. The Xe-Ne-He mixture gas was used to generate the plasma, and the gas discharge characteristics under both total gas pressure and partial gas pressure were investigated. The panel showed a maximum high luminance $7,270cd/m^2$ under bias of 20KHz pulse of 3KV.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.417-422
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• 2010

Atmosphere Plasma of Gas Discharge (APGD) has been used in plasma sources for material processing such as etching, deposition, surface modification and so on due to having no thermal damages. The APGD researches on AC source with high frequency have been mainly processed. However, DC APGD studies have been not. In order to understand APGD further, it is necessary to study on fundamental properties of DC APGD. In this paper, we developed a one-dimensional fluid simulation model with capacitively coupled plasma chamber at the atmosphere pressure (760 [Torr]). Nine kinds of Ar discharge particles such as electron (e), positive ions ($Ar^+$, $Ar_2^+$) and neutral particles ($Ar_m^*$, $Ar_r^*$, $Ar_h^*$, $Ar_2^*$(1), $Ar_2^*$(3) and Ar gas) are considered in the computation. The simulation was worked at the current range of 1~15 [mA]. The characteristics of voltage-current were calculated and the structure of Joule heating were discussed. The spatial distributions of Ar DC APGD and the mechanism of power consumption were also investigated.