• Membrane and Water Treatment
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• v.7 no.1
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• pp.1-10
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• 2016

Ultrafiltration is known to be one of the most commonly applied techniques in water treatment. Membrane fouling is the main limiting factor in terms of process efficiency and restricting it to the manageable degree is crucial. Natural organic matter is often found to be a major foulant in surface waters. Among many known fouling prevention techniques, the membrane chemical cleaning is widely employed. This study focuses on evaluating the cleaning efficiency of polymeric and ceramic membranes with the use of various chemicals. The influence of cleaning agent type and its concentration, membrane material and its MWCO, and cleaning process duration on the recovery of membrane flux was analyzed. Results have shown that, regardless of membrane type and MWCO, the most effective cleaning agent was NaOH.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.177-184
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• 2011

Membrane fouling is an unavoidable phenomenon in operation of seawater reverse osmosis (SWRO) and major obstacle for economic and efficient operation. When fouling occurs on the membrane surface, the permeate flux is decreased, on the contrary, the trans-membrane pressure (TMP) is increased, therefore operation and maintaining costs and potential damage of membranes are able to the pivotal risks of the process. Chemical cleaning process is essential to prevent interruptions for effective RO membrane filtration process. This study focused on proper chemical cleaning condition for polyamide RO membranes of 4 companies. Several chemical agents were applied for chemical cleaning under numbers of operating conditions. Additionally, a monitoring tool of FEEM as autopsy analysis method is adapted for the prediction of organic bio-fouling.

• Clean Technology
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• v.12 no.4
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• pp.250-258
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• 2006

CFC compounds such as CFC-113 and 1,1,1-TCE, etc. have been used in various industries due to their excellent chemical stability, thermodynamic characteristics, non-inflammability and anti-corrosiveness. However, in oder to protect the earth environment, "the Montreal Protocol on substances that deplete the ozone layer" was adopted in 1989 for prevention of production and utilization of these CFC compounds and alternative cleaning agent have been required in the industry. The objective of this study is to develop non-aqueous cleaning agents that do not require major change of cleaning system, have excellent cleaning efficiency, are favorable to the environment, are harmless to the human body, and are not generated corrosive materials. In this work, non-aqueous cleaning agents have been formulated with glycol ether series and paraffinic hydrocarbon series with siloxane, and their physical properties and cleaning efficiencies were analyzed and compared with those of regulated materials. As a result of physical properties measurement of the formulated cleaning agents, it is expected that they may have good penetration ability into contaminated materials due to their properties with low density and low surface tension. Measurement of flash point and vapor pressure of the cleaning agents will be helpful for evaluation of their safety and working environment. The experimental results of cleaning flux, solder and grease by the formulated cleaning agents show that their cleaning abilities of soils were good and that there were no residues on the substance after cleaning. Therefore, alternative cleaning agents which have equivalent cleaning ability to regulating materials, good penetration ability and low hazard to human body, have been developed in this work.

• Clean Technology
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• v.15 no.2
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• pp.81-90
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• 2009

In this study various cleaning evaluation methods were tested and comparatively evaluated to help cleaning industry. In order to select alternative cleaning agents objectively and systematically, various cleaning evaluation methods such as gravimetric, optically simulated electron emission (OSEE), contact angle, and analytical instrument methods were employed for cleaning contaminants such as flux, solder and grease. The analytical instruments used in this work were Fourier transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV-VIS) and high performance liquid chromatography (HPLC). The gravimetric method was able to measure cleaning efficiencies easily and simply, but it was not easy to analyze them precisely because of its limitation in the gravimetric measurement. However, the OSEE technique was able to measure quickly and precisely the clean ability of cleaning agents in comparison with the gravimetric method. The contact angle method was found to be necessary for taking special precaution in its application to the cleaning evaluation due to possible formation of tiny organic film on the substrate surface which might be generated from contaminants and cleaning agents. In case of precision analysis that cannot be done by gravimetric method, fine analytical instruments such as UV-VIS, FTIR and HPLC could be used in analyzing trace amount of flux, solder and grease quantitatively, which were extracted from the surface by special solvents.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1309-1312
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• 2005

A multi-chemical supply system is developed and applied to a wet station, which uses the multi-chemical process in one bath. To control the concentration of two chemicals, control logic of a supply pump is programmed using the programable logic controller (PLC). By using the multi-chemical supply system, wet station with single bath is applied to cleaning process using multi chemicals such as buffed oxide etchant (BOE) and standard clean 1 (SC-1). The concentration of each chemical is measured in the bath to verify the multi-chemical supply system. The control range in the each chemical concentration is measured to 1.33weight% in NH4OH and 0.23weight% in H2O2. The multi-chemical supply system can be movable and usable as an independent module of fixed wet station. By simply midifying the PLC, a multi-chemical supply system can be developed for a wet station.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.86-92
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• 1999

This study was carried out to investigate the effect of chemical cleaning of corrosion product on cooling system made of copper as a basic material and using cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. In addition, the proper amount of NALCO-39L (Nitrite-Borate-BZT mixture) as a inhibitor was determined in order to protect the copper in cooling system against corrosion after chemical cleaning and the effect of corrosion resistance on the copper surface treated was excelent in comparison with surface untreated. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were $Cu_2O$, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400ppm EDTA solution at $60^{\circ}C$. Inhibitor concentration needed to treat the surface of pure copper was 15～20ppm per unit area and corrosion rate of copper treated with 500ppm inhibitor solution for 72 hrs at $60^{\circ}C$ was remarkably decreased as compared with that of pure copper.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.114-119
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• 1999

When NaOCl was generated and put into sea-water cooling machine in order to overcome the biological hindrances against sea-water cooling machine, it was converted into metallic ion, particularly Ca and Mg, as a hydrate in sea-water and is to stick to electrolyte as a side reaction. This phenomena make the distance between the electrolytes narrow to decrease the flow rate, which induces the local vortex flow which erodes the pole plate. Moreover, this increases the resistance of the electrolyte as well as voltage to decrease the electrolytic efficiency, which has curtailed a chlorine yield and caused a pole plate cut. We are able to overcome these problems by chemical cleaning and intend to extend the life-time of electrolyte and to increase output of the sea-water electrolysis facilities by studying optimal policy regarding chemical cleaning of electrolytic cell. Cleaning time of electrolytic facilities is determined when both increase in electrolytic efficiency and decrease in pole-plate voltage are 10%. At this time as operating current of electrolytic facilities is high, operating time is diminished. Whereas, parameter of end point determination according to cleaning is Mg ionic concentration in solution. When we use Cleaner as a 7wt% HCl, cleaning time is about 80min proper. We are able to maintain pole plate performance by protecting against pole plate cut by means of electrolytic by-product, improve operating rate of facilities, and cut down on maintenance expenditure after acidic cleaning.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.557-557
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• 2007

최근 Ruthenium (Ru)은 높은 화학적 안정성, 누설전류에 대한 높은 저항성, 저유전체와의 높은 안정성 등과 같은 특성으로 인해 캐패시터의 하부전극으로 각광받고 있다. 이렇게 형성된 Ru 하부전극은 각 캐패시터간의 분리와 평탄화를 위해 CMP 공정이 도입되게 되었다. 이러한 CMP 공정후에는 화학적 또는 물리적 상호작용에 의해 웨이퍼 표면에 오염물이 발생할 수 있다. CMP 공정중에 공급되는 슬러리에는 부식액, pH 적정제, 연마입자등이 첨가되는데 이때 사용된 연마입자는 CMP 공정후 입자오염을 유발할 수 있다. 그러므로, CMP 공정후에는 이러한 오염으로 인해 cleaning 공정이 반드시 필요하게 되었다. 하지만, Post Ru CMP cleaning에 대한 연구는 아직 미비한 상태이다. 그리하여 본 연구에서는 post Ru CMP cleaning에 대한 연구와 cleaning solution 그리고 첨가제에 따른 영향을 살펴보았다.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.665-672
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• 2004

Chemical cleaning of boiler pipelines is necessary before the commissioning of thermal power plant after many years of construction. Fluid-Dynamic study for the chemical cleaning of boiler piplelines in Young-Heung thermal power plant is carried out. First, flow velocity necessary to sustain and exhaust solid particles in the vertical pipelines is calculated. Second, the flowrate necessary to make the calculated velocities in each vertical pipelines is calculated. Third, all the pipelines are analyzed with the Piping Systems Fluid Flow software to calculated the pressure loss in the pipelines. Finally, the operating point of the applied pump is calculated with the help of the same software.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.140-145
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• 1999

This study was carried out a investigate the effect of chemical cleaning of corrosion product in cooling system made of copper and copper alloy as basic material and used cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were $Cu_2O$, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400 ppm EDTA solution at $60^{\circ}C$.