• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.624-626
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• 1993

The Electrical Charge generated by friction in flowing insulating oil can create hazadous accidents. Neutralization of static charges in the oil during transportation is an obvious method of overcoming the problem of internal electric charge. It is known that SCR(Static Charge Reducer) can neutralize much of this charge by the needle electrode and mixing it with the original charge. In our experiment, a filter to generate static charge was set just befor a measurement pipe, and streaming current from the filter to the earth $I_s$, current from the electrode to the earth $I_e$ and current from the receiving tank to the earth $I_f$ were measured in a steady state. As a result, charge density and needle electrode current increases with increasing of oil temperature. Charge elimination rate decreases with increasing of oil flow rate, and increases with increases of oil temperature. Faraday Cage current decreases with increasing of oil temperature.

• Journal of Aquaculture
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• v.18 no.4
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• pp.280-286
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• 2005

Experiments were conducted to examine the differences in ammonia removal rates with the different filter media between sand and zeolite, the expanding rates between $50\%$ and $100\%$, the water temperatures between $15^{\circ}C$ and $25^{\circ}C$, and the ammonia loading rates between 2 mg/L and 5 mg/L in the seawater fluidized bed filters system (FBF). The 2.1 m high FBF (8.3 cm diameter) consisted of the clear acrylic for the upper half and a PVC pipe for the lower half, Sand and zeolite were used as the filter media in sizes of 0.5$\pm$0.1mm. Each biofilter contained 5.4 L of media. The ammonia removal rates of the biofilter were higher at the $25^{\circ}C$ water temperature than those of the biofilter at $15^{\circ}C$ water temperature, and higher at the $50\%$ expanding rate of filter media than those of the biofilter at $100\%$ expanding rate of filter media. Also, the ammonia removal rates of FBF were higher at 5 mg/L ammonia concentration than those of FBF at 2 mg/L ammonia concentration in rearing water. With these better conditions the ammonia removal rates of FBF per day are practically acceptable and ranged ken 80.6 to $210.6g/m^3$.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.523-532
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• 2015

Hydrocyclone is widely used in industry, for its simple design, high capacity, low maintenance and low operational cost. The objective of this study is to develop hydrocyclone coagulation and filtration system. The system is made of hydrocyclone ballasted coagulation with polyaluminium chloride silicate (PACS) and upflow filter to treat micro particles in urban storm runoff. Roadside sediment particles (< $200{\mu}m$) was mixed with tap water to make various turbid suspensions to simulate urban storm runoff. The filter cartridge was filled with polyethylene media system and ran 1hr per everyday and total operation time were 8.19hrs and backwashing everyday after end of operation. The operation condition of flowrate was $8.2{\sim}11.9m^3/day$ (mean $10.1m^3/day$) and surface overflow rate (SOR) based on filter surface area was $45.5{\sim}65.9m^3/m^2/day$ (mean $55.7m^3/m^2/day$). The range of PACS dosage concentration was 14.0~31.5 mg/L. As the results of operation, the range of removal efficiency of turbidity, SS were 81.0~95.8% (mean 89.5%) 81.8~99.0% (mean 91.4%), respectively. An increase of filtration basin retention time brought on increased of removal efficiency of turbidity and SS, and increase of SOR brought on decreased of removal efficiency. During the first flush in urban area, storm runoff have an high concentration of SS (200~600 mg/L) and the filtration bed becomes clogged and decreased of removal efficiency. Backwashing begins when the drainage pipe valve at the filtration tank bottom is completely open (backwashing stage 1). Backwashing stage 2 was using air bubbles and water jet washing the media for 5 mins and open the drainage valve. After backwashing stage 1, 2, 61.83~64.04%, 18.53~27.51% of SS loading was discharged from filtration tank, respectively. Discharged SS loading from effluent was 7.12~14.79% and the range of residual SS loading in fliter was 2.26~5.00%. The backwashing effects for turbidity, SS were 89.5%, 91.4%, respectively. The hydrocyclone coagulation and filtration with backwashing system, which came out to solve the problems of the costly exchange filter media, and low efficiency of removing micro particles of filter type nonpoint treatment devices, is considered as an alternative system.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.309-315
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• 2005

Volatile organic compounds (VOCs) and odor materials are major sources of air pollution in Ulsan city, where much chemical plants are located. Therefore, it is necessary to develop a new reactor which can remove VOCs and odor materials effectively and be equipped at the end of pipe easily. A modified reactor (bioscrubber trickling filter, BSTF), which have both characteristics of biofilter and bioscrubber, was developed and tested on its reactivity with several VOCs using two types of media, fiber and activated carbon 4- ceramic(A/C). It was observed that the removal efficiencies of several types of VOCs such as acetaldehyde, ethylalcohol, butanol, diethylamine and triethylamine were up to $95\%$ when they had about 100 ppm of initial concentration and 80 seconds of residence time. Good attachment of microorganisms to both media, where it is thought the reaction efficiency can be determined according to the amount of microorganisms attachment, observed with scanning electron microscopy(SEM). Initial pressure drops of the packed bed with both media were 229 $mmH_2O/m$ at A/C column and 670 $mmH_2O/m$, respectively. However, maximum pressure drop of fiber column during the operation was over 1,647 $mmH_2O/m$. Therefore, it was thought that the fiber material would not suitable to use in the local plant as a packed bed media.

• Textile Coloration and Finishing
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• v.25 no.3
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• pp.232-239
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• 2013

In this study, 25gsm melt-blown polypropylene nonwoven for dust-proof/medical masks was finished by the corona discharging treatment. The influence of corona discharging parameters on the filtration efficiency was investigated. Several parameters such as discharging voltage, discharging speed, distance to discharging wire and configuration of discharging system had an effect on filtration efficiency, while the parameters had no effect on breathing resistance. Optimum corona discharging conditions are as follows: Wires were installed on the upper part of the nonwoven and paper pipe was installed on the lower part of the nonwoven having a distance of 5cm. The sequence of wire voltages was +60 kV, +60 kV, 0, -60 kV, and -60 kV. The discharging voltage and speed were 60 kV and 30m/min respectively. The nonwoven treated by corona discharging at the optimum condition showed a filtration efficiency of 80% or more, which is suitable for dust-proof/medical masks.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.813-816
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• 2009

A commercial-scale RDF boiler that its burning capacity is 400 kg-RDF/hr and steam production capacity is 2 ton/hr. It has a chain type stoker and waste heat recovery system. Heat exchanger is vertical water-pipe so that soot blowing and removal is convenient during operation. Dry scrubber, bag filter and activated carbon tower have been installed for the reduction of air pollutant gases and dust. Analysing data of pollutants from stack such as $SO_x$. $NO_x$ and dioxin shows so good results that the boiler system could comply the regulated emission limits.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.471-477
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• 1998

A constant flow-rate control valve provides effective distributions and controls of running water in a pipe system. The noise characteristics were measured to reveal the noise sources depending on pressure differences across a valve. Valve noise is mostly dominated by bubble dynamics under cavitating conditions. In this study, the sound powers from a flow control valve of constant flow rates are effectively normalized. Flow-excited dynamic systems for which there is no strong coupling between the flow and the system response can be described using a linear source-filter model. On this assumption, the normalized sound powers can be decomposed of noise source function and a response function. The source spectra in, terms of cavitation frequency show cavitation events occurring at narrow banded frequencies greater than 10 kHz. There also possibly exist two kinds of cavitating modes based on our experimental data.

• Electrical & Electronic Materials
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• v.7 no.3
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• pp.236-242
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• 1994

In this paper, the streaming electrification characteristics of insulating oil were examined when the oil is contacted with solid materials in a circulating system. The streaming current($I_s$) increases with increasing oil velocity and temperature, and electrification properties depend on species of metal materials. $I_s$ in the gauze-contained electrification apparatus increases with increasing oil temperature below the temperature of 43[>$^{\circ}C$], but decreases above 43[>$^{\circ}C$]. On the other hand, $I_s$ is positive electrificated for the pipe of Fe, Cu, while it is negative electrificated for Sus. When insulating oil flows through a car fuel filter, $I_s$ increases linearly with increasing oil temperature.

• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.25-31
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• 2012

A computational study on the improvement of the pressure loss of intake system, which is located at engine manifold of the combat vehicle, has been conducted using a finite-volume-based, Reynolds-Averaged Navier-Stokes (RANS) solver. The computational result of the pressure loss through the air cleaner is in good agreement with equivalent experimental data. A parametric study was done for improving of the pressure loss of intake system over the baseline case. The effects of five primary parameters such as the height of inlet, the width of interconnection pipe, the shape of drain chamber and the diameter of filter housing were considered in this study. Consequently, this computational investigation can contribute to finding an optimal guideline for the idea of improvement in the pressure loss of intake system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1380-1384
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• 2006

Sediments deposited on lateral drain pipes in a tunnel make lateral porous pipes clogged. Since the safety of the tunnel can be affected by this phenomenon, it requires a regular maintenance of the lateral drain pipes. In this study, a series of centrifugal tests were conducted in order to find out the method which can reduce the clogging effect considerably. Four different types of tunnel drain configurations were selected in the experiments. By analysis of sediments for each configuration, the optimum drain configuration that can minimize sedimentation of cement constituents was investigated. As a results, the existing drain configuration which uses filter concrete appear to produce much sediments. In contrast, the new drain configuration appears to be able to reduce sedimentation ratio up to almost 50% comparing with the existing one. From these observations, it may be concluded that the new drain configuration, in which the lateral porous pipes of a tunnel are surrounded by gravel layer and non-woven geotextile, has high efficiency in maintenance.