• Membrane Journal
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• v.19 no.3
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• pp.252-260
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• 2009

The effects of the treatment of an acidic solution at pH 2 on polyacrylonitrile ultrafiltration (UF) membranes were investigated using a circular cross-flow filtration bench with a membrane module. A substantial reduction in the membrane permeability was observed after 80 hours' treatment of the acidic solution. In addition, the analyses of the sample solutions by ultraviolet/visible absorption spectroscopy and gas chromatography/mass spectrometry (GC/MS), which were taken from the feed tank as a function of the treatment time, showed that a new organic compound was produced in the course of the treatment. From a thorough search of the mass spectral library we presumed the new compound to be 1,6-dioxacyclododecane-7,12-dione (DCD), one of the well-known additives for polyurethane. Based on further experimental results, including the scanning electron microscope (SEM) images and the solid-state NMR spectra of the membranes used for the treatment of the acidic solution, we suggested that the decrease of the permeate flux resulted not from the deformation of the membranes, but from the fouling by DCD eluted from the polyurethane tubes in the filtration bench during the treatment. Those results imply that the reactivity to an acidic solution of the parts comprising the filtration bench is as important as that of the membranes themselves for effective treatments of acidic solutions, for efficient chemical cleaning by strong acids, and also in determining the pH limit of the solutions that can be treated by the membranes.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.209-218
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• 1998

Ca-deficiency frequently observed in the hydroxyapatite powders prepared by precipitation which is known to be deleterious for its application to biomaterials was prevented by the technique developed in this study. In addition the prepared powder has been revealed to be quite active that full density is achieved at temperatures as low as 100$0^{\circ}C$ Instead of using N2 air was chosen as the processing atmosphere during the precipitation and aging of hydroxyapatite. {{{{ {CO }`_{3 } ^{2- } }} ions from the processing atmosphere(air) substitute partly for {{{{ {PO }`_{4 } ^{3- } }} ions in the hydroxyapatite and its content can be controlled by pH of the solution where the pre-cipitation reaction occurs.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.17-22
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• 2006

This study is about backwash condition and membrane fouling at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06m^3/d$. The result of the test, Backwash cycle time and duration time had a significant effect on the efficiency of system and backwash. Backwash duration time was determined to be fixed in 30 seconds for the system with more than 95% recovery rate, It needed 30 minute backwash frequency. During the continuous operation, membrane fouling was analyzed by determining the filtration resistance ($R_i$) and cake layer resistance ($R_c$). At the initial stage, filtration resistance highly influenced the fouling behavior. But after 1.5 hours, cake layer resistance became more important than filtration resistant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.14-19
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• 2019

In this study, the possibility of using marine life for cosmetic materials was assessed by establishing a fermentation process of seaweed, such as Ecklonia cava, Enteromorpha prolifera, Chondria crassicaulis, Eiseniabicyclis, Codium fragile, Seaweed furcata, Gloiopeltis tenax, Grateloupia elliptica, Undaria pinnatifida, and Saccharina japonica. Lactobacillus sakei isolated from Kimchi was used for effective fermentation and whole milk powder was used as an additive. 2.0 % of crushed seaweed and 1.0 % of whole milk powder were added and afterwards, 1.0 % Lactobacillus sakei was added after cooling to $40^{\circ}C$. After cooling and filtering the fermented product, butylene glycol, glycerine, and 1,2-hexandiol, which have the effect of a preservative, were added to mix and complete the final product. Among the ten kinds of seaweeds, the process was found to be highly effective in the fermentation of Ecklonia cava, Codium fragile, Undaria pinnatifida, and Saccharina japonica. The amount of fermentable substances in cosmetics was determined and the safety of the raw material was verified using the HET-CAM (The Hen's egg test-Chorioallantoic membrane) test.

• Food Engineering Progress
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• v.14 no.4
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• pp.359-366
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• 2010

Large-scale preparation steps of antithrombotic materials from wood ear mushroom (Auricularia auricular-judae) were established as follows. Grounded dry wood ear mushroom was extracted with 75% ethanol and its precipitate was extracted with $76^{\circ}C$ water for 2 hr followed by filter pressing. The filtrate was then concentrated by vacuum and extracted with 80% ethanol, and the resulting precipitate was then freeze-dried. The formula of the product was determined using consumer susceptibility tests as follows; mushroom extract 90.5%, high fructose corn syrup 2.0%, $\beta$-cyclodextrin 1.5%, fructo-oligosaccharide 2.0%, pear puree 4.0%. When the packed products were stored at 25, 37, or $45^{\circ}C$ for 8 weeks, there were no noticeable changes in water activity, moisture content, pH, and acidity. The viable cell number of total bacteria was slightly increased during the storage period at 25 and $37^{\circ}C$, The total bacteria were not detected in the product when stored at $45^{\circ}C$. When the product was injected intravenously into rat at the level of 1,000 mg/kg, antithrombotic activities such as activated partial thromboplastin time, thrombin time, prothrombin time, and FIB were increased when compared with the control group. When the product was administrated orally into rat at the level of 500 mg/kg, it showed the same antiplatelet activity to aspirin.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.223-223
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• 2003

광통신에는 광신호의 전송과 광신호 처리에 처리 과정에서 광 손실을 수반하므로 각 요소별로 광신호 증폭이 반드시 필요하다. 또한 광통신망의 완전 광화를 위해서는 제조 공정이 간단하여 가격이 저렴하고, 높은 신뢰성과 높은 증폭 효율을 가지면서 다른 부품과의 집적화가 가능한 광도파로형 광증폭기가 요구되고 있다 그러나 실리카는 광통신 파장대인 1.55$\mu\textrm{m}$대역의 증폭이 가능한 Er 이온에 대한 용해도가 50ppm 이하로 낮아 lmol% 이상 고농도로 Er 이온을 첨가하여 높은 증폭 효율을 얻는데 한계를 가지고 있다. 따라서 본 연구에서는 Er 이온에 대하여 높은 용해 특성을 가지고 있어 고농도 Er 이온 도핑이 가능한 알루미나에 Er을 1-2 mol% 첨가하여 광발광 특성을 조사하였다. Er이 첨가된 알루미나 나노 졸은 Al(NO$_3$)$_3$ㆍ9$H_2O$와 Er(NO$_3$)$_3$.5$H_2O$가 일정 양 용해된 수용액에 NH$_4$OH를 가하여 침전물을 얻고 여과 및 수세하여 졸 입자의 함량이 약 5wt%가 되게 이온교환수와 해교제인 초산을 소량 가하여 10$0^{\circ}C$에서 약 50시간 열처리하는 방법으로 제조하였다. Er이 첨가된 알루미나 코팅막은 Er 이 첨가된 알루미나 나노 졸에 GPS(3-glycidoxypropyltriethoxysilane)를 Al에 대하여 7 mol% 가하여 스핀 코팅법으로 제조하였다. Si 기판에 코팅하고, 상온에서 90$0^{\circ}C$까지 각 1시간 열처리한 코팅막의 광 발광 특성은 Er 이온의 첨가량과 열처리로 변화된 알루미나 코팅막의 결정상과 연계하여 논의 될 것이다. X-선 회절법으로 분석한 알루미나 코팅막의 온도에 따른 결정상은 boehmite 상에서 약 50$0^{\circ}C$이후에 ${\gamma}$-Al$_2$O$_3$로 전이하고 있다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1274-1279
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• 2006

The formation characteristics of $BDOC_{rapid}$ and $BDOC_{slow}$ with different ozone dosages for 3 different kinds of waters from Maeri raw water in the down stream of Nakdong river, Hoidong reservoir water in Busan City and treated Maeri raw water(sand filtered) has been investigated in this study. The ozone dosages for producing maximum $BDOC_{total}$ in the Maeri raw water, Hoidong reservoir water and sand filtered water of Maeri were 0.9, 1.1 and 1.4 $mgO_3$/mgDOC respectively. It could be concluded that the ozone dosages for formations of maximum $BDOC_{total}$ were determined by characteristics of water. The ozone dosages for producing maximum $BDOC_{rapid}$ in the Maeri raw water, Hoidong reservoir water and sand filtered water of Maeri were 0.9, 0.9 and 1.0 $mgO_3$/mgDOC respectively that were same or lower than the used ozone dosages for producing maximum $BDOC_{total}$. $BDOC_{slow}$ was being formated and increased continuously with the higher ozone dosages which were the used ozone dosages for maximum formation of $BDOC_{total}$ and $BDOC_{rapid}$. For the best results of a pre-treatment of biofiltration, the optimum ozone dosage ranges in formation of $BDOC_{rapid}/BDOC_{total}$ were $0.6{\sim}1.0\;mgO_3$/mgDOC that were lower than the ozone dosage ranges of $0.9{\sim}1.4\;mgO_3$/mgDOC for the maximum formation $BDOC_{total}$. The reported results indicated that the best and effective ways from economic and technical points of view to determine the optimum ozone dosages of the pretreatment of biofilteration process were investigating and classifying BDOC.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.571-576
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• 2011

Characteristics of bubble driven wakes were investigated in a simulated GTL process(0.102 m ${\times}$ 1.5 m in height) with viscous liquid medium. Effects of gas velocity(0.04 ~ 0.12 m/s) and liquid viscosity(0.001 ~ 0.050 $Pa{\cdot}s$) on the wake characteristics such as rising velocity, frequency, size and holdup were determined by employing a resistivity probe method. The wake phase formed behind the rising multi-bubbles as well as single bubbles were detected effectively from the conductivity fluctuations measured by the probe. Compressed, filtered and regulated air and aqueous solutions of Carboxy Methyl Cellulose(CMC) were used as a dispersed gas phase and a continuous liquid medium, respectively. It was found that the rising velocity and size of wake phase increased with an increase in gas velocity or liquid viscosity. The holdup and frequency of wake phase increased with increasing gas velocity due to the increase of gas input into the process with increasing gas velocity. However, the values of holdup and frequency of wake phase decreased with increasing liquid viscosity, since the size of bubbles and thus that of wakes increased with increasing liquid viscosity. The ratio of wake holdup to that of gas phase, which was in the range of 0.25 ~ 0.48, increased with an increase in liquid viscosity but decreased with gas velocity. The wake characteristics were well correlated in terms of operating variables within this experimental conditions.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.444-451
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• 2016

Most research on membrane fouling models in the past are based on theoretical equations in lab-scale experiments. But these studies are barely suitable for applying on the full-scale spot where there is a sequential process such as filtration, backwash and drain. This study was conducted in submerged membrane system which being on operation auto sequentially and treating wastewater from G-water purification plant in Incheon. TMP had been designated as a fouling indicator in constant flux conditions. Total volume of inflow and SS concentration are independent variables as major operation parameters and time-series analysis and prediction of TMP were conducted. And similarity between simulated values and measured values was assessed. Final prediction model by using genetic algorithm was fully adaptable because simulated values expressed pulse-shape periodicity and increasing trend according to time at the same time. As results of twice validation, correlation coefficients between simulated and measured data were $r^2=0.721$, $r^2=0.928$, respectively. Although this study was conducted limited to data for summer season, the more amount of data, better reliability for prediction model can be obtained. If simulator for short range forecast can be developed and applied, TMP prediction technique will be a great help to energy efficient operation.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.237-245
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• 2017

This study was aimed at investigating effluent water quality and proposing reuse possibilities for 12 sewage treatment plants discharged more than $5,000m^3/day$ in order to recycle the sewage treatment plant effluent of Jeollabuk-do effectively. Additionally, a laboratory scale test for reprocessing water discharge was performed. Categories of reclaimed sewage water reuse were divided into 7 topics and analyzed a total of 28 items including 16 heavy metals based on water quality standard. As a results, color, BOD, TN, chloride and Electrical Conductivity (EC) exceeded reused water quality standard. In particular, color and TN exceeded in 8 and 5 sewage treatment plants, respectively. The value of chloride and EC were high in sewage treatment plants including the food and industrial wastewater. At 4 sewage treatment plants were possible to reuse without re-treatment. The laboratory scale test was conducted to SandFilter (SF)-Granular Activated Carbon (GAC)-MicroFiltraion (MF)-Reverse Osmosis (RO). Both the removal efficiencies and economic feasibility of total E. coli., color and Suspended Solid (SS) suited in case using the SF-GAC treatment method. The removal of chloride and EC had little effect in the case of SF-GAC-MF system, but RO showed over 90% of removal efficiency. After using SF-GAC process only, the concentration of $UV_{254}$ decreased sharply from 0.3651 /cm to 0.0306 /cm and it showed over 92% of removal efficiency rate. In conclusion, for the effective reuse of sewage discharged water, water quality and the surrounding terrain of treatment plants should be all taken into account. If it needed for the reprocessing, both the selection for treatment and economic combination treatment methods will have to be considered.