• Environmental Engineering Research
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• v.21 no.1
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• pp.45-51
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• 2016

Membrane bioreactor (MBR) and reverse osmosis (RO) membrane system was applied to the treatment and reclamation of textile wastewater in Thailand. An experiment was carried out to determine the fouling behavior and effect of anti-scalant and biocide addition to flux decline and its recovery through chemical cleaning. The RO unit was operated for one month after which the fouled membranes were cleaned by sequential chemical cleaning method. RO flux was found rapidly declined during initial period and only slightly decreased further in long-term operation. The main foulants were organic compounds and thus sequential cleaning using alkaline solution followed by acid solution was found to be the most effective method. The provision of anti-scalant and biocide in feed-water could not prevent deposition of foulant on the membrane surface but helped improving the membrane cleaning efficiencies.

• Journal of KIISE
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• v.43 no.6
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• pp.627-635
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• 2016

When many processes issue write operations alternately on Log-structured File System (LFS), the created files can be fragmented on the file system layer although LFS sequentially allocates new blocks of each process. Unfortunately, this file fragmentation degrades read performance because it increases the number of block I/Os. Additionally, read-ahead operations which increase the number of data to request at a time exacerbates the performance degradation. In this paper, we suggest a new cleaning method on LFS that minimizes file fragmentation. During a cleaning process of LFS, our method sorts valid data blocks by inode numbers before copying the valid blocks to a new segment. This sorting re-locates fragmented blocks contiguously. Our cleaning method experimentally eliminates 60% of file fragmentation as compared to file fragmentation before cleaning. Consequently, our cleaning method improves sequential read throughput by 21% when read-ahead is applied.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.905-909
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• 2003

This paper describes a shower type ultrasonic cleaning system using particle acceleration, developed for better effectiveness in washing out agricultural chemicals from fruits or vegetables, compared to the existing bath type ultrasonic cleaning system. The shower type system consists of a signal generator, a transducer, and a spouting nozzle, mainly. The system has been tested based on the method recommended by Korea Food and Drug Administration. It is found that shower type system shows better performance and cost-effectiveness than the bath type system that is commercially available .

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.923-924
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• 2012

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3168-3172
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• 2007

As the minimum feature size decreases, control of contamination by nanoparticles is getting more attention in semiconductor process. Cleaning technology which removes nanoparticles is essential to increase yield. A reference wafer on which particles with known size and number are deposited is needed to evaluate the cleaning process. We simulated particle trajectories in the chamber by using FLUENT and designed a particle deposition system which consists of scanning mobility particle sizer (SMPS) and deposition chamber. Charged monodisperse particles are generated using SMPS and deposited on the wafer by electrostatic force. The experimental results agreed with the simulation results well in terms of particle number and deposition area according to particle size, flow rate and deposition voltage.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.578-587
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• 2009

In this paper, the characteristics of incompressible flow in a tube type marine fuel oil filter have been investigated. Fluent program has been used to obtain the solutions for the problems of three-dimensional, turbulent fuel oil flow in a filtering system. The inlet flow field is assumed to be uniform. The velocity and pressure distributions were obtained using Darcy's law. The increase of inlet velocity for cleaning fuel oil may cause some problems like vibration of the filter element. It was also required to consider the distribution of cleaning velocity because the worst distribution of cleaning velocity may cause the local insufficient cleaning effect and furthermore the effective filtration area can be reduced. The simulated results show that the computer code can be successfully applied for simulation of the complex base oil flow through the porous media. This paper could be applied to the design of auto-backwashing filtering system as design factor.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.299-304
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• 2010

We should manage the target locations according to the deterioration degree of the ballast for the rational and economical ballast cleaning. For this, it's required to define the logics calculating the crushing rates and suggest the threshold values for the ballast cleaning. This paper introduce the system modules that estimate the ballast's deterioration degree refers to the results of the previous study("A Study on the Crushing Characteristic of the Ballast Gravel at High-Speed Railroad", Journal of the Korean Society for Railway, Vol.11, No.4, pp.384~389), enroll the target locations where the ballast cleaning is required.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1279-1280
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• 2013

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2001.05a
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• pp.135-140
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• 2001