• Structural Engineering and Mechanics
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• v.62 no.2
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• pp.163-170
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• 2017

This study presents a particle-wall filtration model for predicting the particle motion behavior in a typical rotational flow field-filtration in blower system of cooker hood. Based on computational fluid dynamics model, air flow and particles has been simulated by Lagrangian-particle/ Eulerian-gas approaches and get verified by experiment data from a manufacturer. Airflow volume, particle diameter and local structure, which are related to the particle filtration has been studied. Results indicates that: (1) there exists an optimal airflow volume of $1243m^3/h$ related to the most appropriate filtration rate; (2) Diameter of particle is the significant property related to the filtration rate. Big size particles can represent the filtration performance of blower; (3) More than 86% grease particles are caught by impeller blades firstly, and then splashed onto the corresponding location of worm box internal wall. These results would help to study the micro-particle motion behavior and evaluate the filtration rate and structure design of blower.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.466-466
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• 2011

There have been several methods to fabricate carbon nanotube (CNT) emitters, which include as-grown, spraying, screen-printing, electrophoresis and bonding methods. Unfortunately, these techniques generally suffer from two main problems. One is a weak mechanical adhesion between CNTs and the cathode. The as-grown, spraying and electrophoresis methods show a weak mechanical adhesion between CNTs and the cathodes, which induces CNT emitters pulled out under a high electric field. The other is a severe degradation of the CNT tip due to organic binders used in the fabrication process. The screen-printing method which is widely used to fabricate CNT emitters generally shows a critical degradation of CNT emitters caused by the organic binder. Such kinds of problems induce a short lifetime of the CNT field emitters which may limit their practical applications. Therefore, a robust CNT emitter which has the strong mechanical adhesion and no degradation is still a great challenge. Here, we introduce a simple and effective technique for fabrication of CNT field emitter, namely filtration-taping-transfer method. The CNT emitters fabricated by the filtration-taping-transfer method show the low turn-on electric fields, the high emission current, good uniformity and good stability. The enhanced emission performance of the CNT emitters is mainly attributed to high emission sites on the emitter area, and to good ohmic contact and strong mechanical adhesion between the emitters and cathodes. The CNT emitters using a simple and effective fabrication method can be applied for various field emission applications such as field emission displays, lamps, e-beam sources, and x-ray sources. The detail fabrication process will be covered at the poster.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.262-271
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• 2015

Laboratory study was undertaken to pursue the filter performance of a micro-filter module employing highly porous fiber media under a high filtration rate (over 1,500 m/day), faster than that of any conventional filter process. The effects of filtration rate, head loss, raw water turbidity, and filter aid chemicals on filter performance were analyzed. In spite of the extremely high filtration rate, the filter achieved an attractive efficiency, reducing the raw water turbidity by over 80%. As with other filter systems, the filter aid used (PAC in this study) greatly affected the performance of this particular fiber filter. Long term repetitive runs were additionally carried out to confirm the reproducibility of the filter performance. Finally, a comparison was carried out with other high rate filter systems which are either being tested for use in experimental studies, or are already commercially available.

• Membrane Journal
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• v.24 no.3
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• pp.194-200
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• 2014

The purpose of this study was to evaluate the performance of newly developed Large Pore Micro-Filtration (LPMF) membrane in Lab size for the application of water treatment, and to find its problems with solutions. The out-to-inside filtration hollow fiber LPMF membrane of which average pore size was $5{\mu}m$ was used at this study and its material was the PET braid reinforced PVDF. Filtration tests were done through gravity with 30 cm water head difference or pressure below 1.5 bar, and the backwash was done instantaneously with the filtrate after pressurizing it to about 4 bar. The water flux of the LPMF membrane with 0.2 bar TMP (Trans Membrane Pressure) was 2 times higher than $0.4{\mu}m$ MF membrane with $0.05{\mu}m$ UF filtrate of the tap water and it was measured also with 20~30 cm water head difference which showed over 800 LMH at 30 cm water head difference. And Time-To-Filter (TTF) was performed by using $5{\mu}m$ filter paper to optimize coagulants and dosage which enhanced filtrate's turbidity and stabilized filtration flux. When the LPMF was operated with 30 cm gravity with very high dose of inorganic coagulants, the flux was maintained over 80 LMH with 93.5~99.5% turbidity removal. Especially, the filtration was maintained stably in the flux and about 97% of the recovery rate by instantaneous pressurized backwash with about 4 bar of the filtrate when the packing density was about 19%. But there was instability in filtration, since the TMP was continuously going up by inefficient backwash when the packing density was 43%.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.436-441
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• 2013

An experiment using a 5 m-long sand column was performed to evaluate the resisting capability against micro-pollutants of the infiltration gallery, multi-purpose filtration pond and riverbank/bed filtration, of which the filtration distance is becoming increasingly shorter in Korea. Results suggested that the Korean riverbed sand contained significant amount of organics, resulting in a relatively vigorous adsorption of chloride ion on the sand surface. Results also indicated that while phenol was not detected in the column filtrate, both 1,4-dioxane and diazinon were exposed to adsorption by the sand as they moved through the column, decreasing their peak concentrations during the movement. It can be expected that the peak concentrations will diminish significantly in the practical scale due to its longer travel distance.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.59-67
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• 2014

Purpose: The present study was aimed to compare the results of disinfection efficacy tested by membrane filtration method with dilution-neutralization method to develop the standard methods for evaluating disinfection efficacy of contact lens care products and to provide the result of disinfection efficacy of commercially available contact lens care products in domestic market. Methods: The results of disinfection efficacy against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Candida albicans evaluated by membrane filtration method as a FDA standard and dilution-neutralization method as newly being a KFDA standard were compared and the disinfection efficacy of 16 multi-purpose solutions was further evaluated. Results: The disinfectants and contact lens care products having strong disinfection efficacy showed same results in both membrane filtration method and dilution-neutralization method. In case of contact lens care products having weak disinfection efficacy, the number of micro-organisms was not able to count since the colony was aggregated when evaluated by membrane filtration method. However, the number of micro-organisms was able to exactly count when evaluated by dilution-neutralization method. In addition, some commercially available contact lens care products did not meet disinfection standard and especially, their disinfection effect was often weak against Serratia marcescen and Candida albicans. Conclusions: It is concluded that dilution-neutralization method will be useful to evaluate disinfection efficacy since it is possible to count micro-organisms more precisely even with small amount of sample and check the results faster compared with membrane filtration method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.277-284
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• 2005

Micro-filtration (MF) or ultra-filtration (UF) system with hollow-fiber cartridge was introduced in order to improve the Quality level of commercial foxtail millet Yakju, which has an off-flavour and/or undesired colour after the thermal treatment. The filtration effects of cartridges such as MF (0.65, 0.45, 0.2, 0.1 $\mu$m) and UF (500 K dalton) were investigated. The physicochemical and sensory characteristics of the Yakju were then evaluated during the 6 months storage at room temperature. The exclusion ability of microorganism in samples was confirmed in all cartridges, but 0.45 pm MF-cartridge was suitable in the Yakju manufacture due to its superior filtration rate and efficiency. Changes in reducing sugar and colour difference of foxtail millet Yakju untreated or treated by heat ($65^{\circ}C$${\times}$10 min) were observed during the storage; after 6 months the L-value of thermal-treatment sample was decreased and its b-value, however, significantly increased so that its color became dark, in comparison to non-thermal treatment sample. This decrease of reducing sugar is assumed that color change is associated with non-enzymatic browning reaction. Sensory Quality of foxtail millet Yakju produced by non-thermal treatment was better than that of thermal treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.7
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• pp.557-561
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• 2001

Chemical mechanical polishing (CMP) process has been widely used to planarize dielectric layers, which can be applied to the integraded circuits for sub-micron technology. Despite the increased use of CMP process, it is difficult to accomplish the global planarization of in the defect-free inter-level dielectrics (ILD). Especially, defects such as micro-scratch lead to severe circuit failure which affect yield. CMP slurries can contain particles exceeding 1㎛ in size, which could cause micro-scratch on the wafer surface. The large particles in these slurries may be caused by particles agglomeration in slurry supply line. To reduce these defects, slurry filtration method has been recommended in oxide CMP. In this work, we have studied the effects of filtration and the defect trend as a function of polished wafer count using various filters in inter-metal dielectrics(IMD)-CMP process. The filter installation in CMP polisher could reduce defects after IMD-CMP process. As a result of micro-scratch formation, it is shown that slurry filter plays an important role in determining consumable pad lifetime. The filter lifetime is dominated by the defects. We have concluded that slurry filter lifetime is fixed by the degree of generating defects.

• ETRI Journal
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• v.41 no.1
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• pp.32-41
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• 2019

We propose a speckle reduction technique in electronic holographic display systems, where digital micro-mirror array devices are used as spatial light modulators. By adopting a programmable filtration in a general 4-f optic configuration, it is shown that the signal spectrum components in the frequency domain of a viewing-window-based holographic display system can be selectively filtered. Compared to the widely utilized single-sideband filtration techniques in electronic holographic display systems, our proposed programmable filtration can be utilized to effectively reduce the speckles in the reconstruction of point-cloud-based computer-generated holograms. Experimental results are presented to verify our proposed concept.

• Membrane Journal
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• v.14 no.1
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• pp.66-74
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• 2004

Total resistance of membrane in a micro-filtration system using a metal membrane was mainly attributed to the permeate resistance of cake layer($R_c$), which was formed by deposited particles from the physico-chemical interactions of solids on membrane surface. Intermittent back ozonation was highly effective than the air backwashing for fouling reduction. As far the operational effect, under same ozone injection, the increase of gas flow-rate was more favorable than the increase of injection time far the recovery of permeation flux. As the filtration time was longer, the effect of flux recovery by intermittent back-ozonation decreased. Therefore, it is preferable to operate membrane cleaning before the foulant is consolidated on membrane surface.