• 한국환경과학회지
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• 제25권11호
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• pp.1467-1474
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• 2016

In response to the water shortage problem, continued attempts are being made to secure consistent and reliable water sources. Among various solutions to this problem, wastewater effluent is an easy way to secure the necessary supply, since its annual output is consistent. Furthermore, wastewater effluent has the advantage of being able to serve various purposes, such as cleaning, sprinkling, landscaping, river management, irrigation, and industrial applications. Therefore, this study presents the possible use of reclaimed industrial wastewater treated with Birm filters and a UF membrane, along with an analysis on membrane fouling. The preprocessing stage, part of the reclamation process, used Birm filters to minimize membrane fouling. Since this study did not consider heavy metal levels in the treated water, the analyses did not include the criterion for irrigation water quality. However, the wastewater reclaimed by using Birm filters and a UF membrane met every other requirement for reclaimed water quality standards. This indicated that the treated water could be used for cleaning, channel flow for maintenance, recreational purposes, and industrial applications. The analysis on the fouling of the Birm filter and UF membrane required the study of the composition and recovery rate of the membrane. According to SEM and EDX analyses of the UF membrane, carbon and oxygen ion composition amounted to approximately 57%, whereas inorganic matter was not detected. Furthermore, the difference in the recovery rates of the distressed membrane between acidic and alkaline cleaning was more than ~78%, which indicated that organic rather than inorganic matter contributed to membrane fouling.

• 대한불안의학회지
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• 제16권2호
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• pp.106-112
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• 2020

Objective : Social anxiety disorder (SAD) is characterized by fear of social threat and exhibits limbic hyper-reactivity toward social stimuli such as emotional faces. A previous study identified the uncinate fasciculus (UF) sub-tract as particularly related to facial memory. To explore the white matter tract relating to face-specific brain regions, we investigated the UF sub-tract in SAD. Methods : The diffusion tensor images of 22 patients with SAD and 20 healthy controls were analyzed with tractography. The UF sub-tract was delineated using the regions of interest of face patches in the anterior temporal lobe and the orbitofrontal cortex, and fractional anisotrophy (FA) and total number of streamlines (ST) were analyzed. We examined the group comparison of FA and ST of the UF sub-tract and correlations of FA and ST with the social anxiety symptoms such as the Liebowitz Social Anxiety Scale (LSAS), the Social Interaction Anxiety Scale (SIAS), the Social Phobia Scale (SPS) and the Fear of Negative Evaluation scale (FNE) in SAD. Results : There were no group differences in FA and ST of the UF sub-tract. However, negative correlations were observed between ST of the right UF sub-tract and severity of social anxiety symptoms (LSAS, r_s=-0.480, p=0.024; SIAS, r_s=-0.580, p=0.005; SPS, r_s=-0.590, p=0.004; FNE, r_s=-0.675, p=0.001) in patients with SAD. Conclusion : Although patients with SAD did not show quantitative abnormalities in the UF sub-tact connecting face-specific brain regions, this structure seems to play a role in the symptom severity of SAD.

• 한국미생물·생명공학회지
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• 제22권1호
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• pp.99-105
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• 1994

In this study we compared traditional cheesemaking process with the process utilizing ultrafiltration(UF) system. The whole milk retentates were prepared by ultrafiltration to volume concentration ratio(VCR) of 2.00:1, 2.25:1 and 2.50:1. Along with the untreated whole milk, there were studies in terms of the change of pH, titratable acidity and Soxhlet-Henkel($\circ $SH) value by mesophilic lactic starter and curd formation by rennet during Gouda cheese manufacture. Due to the increase of buffering effect titratable acidity and $\circ $SH value increased with the higher concentration ratio. When inoculated with the same volume of mesophilic lactic starter, less pH change occurred in UF retentates than in control milk. When added 0.0025% rennet, UF retentates coagulated 16~ 17 minutes ealier then the control milk. Gouda cheese yield from raw milk and UF retentates was 12.5~13.1% equally, but yield efficiency of UF retentate cheese was slightly higher than that of the raw milk cheese. Quantity of whey from retentate cheese was inversely related to VCR. But whey from retentate cheese contained higher percentage of amjor components than that from control milk cheese. In early ripening, the concentrations of lactose and soluble nitrogen compound were higher in retentate cheeses. Lactose content of control milk cheese was 3.49% and that of 2.00:1. 2.25:1, 2.50:1 VCR retentate was 3.77%, 4.89%, 7.03%, respectively. Thus, the more concentrated cheese contained a higher amount of lactose and all the lactose was hyerolyzed durion 35-day ripenion period. Soluble nitrogen compound of control milk cheese was 1.22% and that of UF cheeses was 1.82~2.06%. After 20-day ripening, soluble nitrogen compound increased starply in UF cheese.

• 한국막학회:학술대회논문집
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• 한국막학회 2002년도 추계 총회 및 학술발표회
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• pp.99-102
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• 2002

• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.42-51
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• 2006

The this study, the effect of rice husk flour (RHF) as scavenger on formaldehyde emission rate and formaldehyde content from urea-formaldehyde (UF) resin bonded RHF content wood particleboards (PB). Two type of particle size ($30{\mu}m$ and $300{\mu}m$) of RHF was premixed with the UF resin at 5% and 15% by weight. The performance of UF resins is greatly influenced by the curing characteristics in their curing processing. The curing behavior was monitored activation energy ($E_a$) by DSC and pH variation according to RHF contents. PB with dimensions of $27cm{\times}27cm{\times}0.7cm$ was prepared at a specific gravity of 0.75 using $E_1$ and $E_2$ class UF resins. Formaldehyde emission and formaldehyde content from RHF filled PB bonded with UF resin was measured by 24 h desiccator and perforator method, respectively. RHF causes an increased pH of UF resin. $E_a$ of the modified UF resin decreased independently of RHF particle size. As the pH and the $E_a$ variation of the UF resin containing RHF increased, the amount of formaldehyde content decreased. The formaldehyde emission and formaldehyde content levels of the PB bonded with 15 wt% of $30{\mu}m$ RHF and $E_2$ type UF resin were low and satisfied grade $E_1$, as measured by 24 h desiccator and perforator method. The result of a comparison between 24 h desiccator and perforator test using PB showed that the linear regression analyses show a good correlation between the results for the 24 h desiccator and the perforator tests. The linear regression of a correlation between the desiccator and the perforator was Y=4.842X-0.064 ($R^2=0.989$). RHF was effective at reducing formaldehyde emission and formaldehyde content in urea-formaldehyde adhesives when used as scavenger.

• 상하수도학회지
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• 제19권1호
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• pp.38-46
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• 2005

In this research, we tried to combine the coagulation/sedimentation process as pre-treatment with UF membrane filtration to reduce the membrane fouling and to improve the permeate water quality. We used the Jet Mixed Separator (JMS) as coagulation/sedimentation process. We observed that the HPC and E.Coli can't be removed through the direct UF memebrane filtation of surface water. The removal efficiency of dissolved organic substances, indicated by E260 and DOC, was 40% and 15%, respectively. However, the removal efficiency of it increased two time as a result of combination of JMS process as coagulation/sedimentation pre-treatment. This was resulted from the formation of high molecular humic micro-floc through JMS process. The accumulation amount of irreversible cake layer which was not removed by backwashing was less than direct UF membrane filtration of surface water. Moreover, the loading rate of fouling induced substances, such as humic substances and suspended substances, on membrane surface decreased drastically through JMS process. As a result, the accumulation amount of irreversible cake on membrane surface was decreased.

• 대한환경공학회지
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• 제27권8호
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• pp.799-806
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• 2005

응집-UF 정수공정시 응집 전처리 공정에 있어 완속혼합없이 급속혼화만으로 충분한 응집의 효과를 기대할 수 있으며, 급속혼화장치로 in-line static mixer를 사용한 경우가 기존의 back mixer를 사용 한 경우보다 롤은 DOC 제거효율을 얻을 수 있었다. 또한, 적정 주입량인 16 mg alum/L에서 막의 투과 flux 감소가 가장 적게 나타났으며 적정 주입량보다 너무 적거나 또는 너무 많은 경우 모두 막의 투과 fiux 감소가 크게 나타났다. 또한 막의 fouling에 크게 영향을 미치는 것은 hydrophobic 물질로 이는 응집 전처리시 효과적으로 제거되어짐으로써 막의 투과 flux 감소를 줄일 수 있었다.

• 한국세라믹학회지
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• 제51권4호
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• pp.337-343
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• 2014

A single layer ultrafiltration(UF) ceramic membrane was prepared using boehmite sol. Boehmite was synthesized using a typical sol-gel process with optimization of the viscosity, pH, molar ratio of aluminum isopropoxide(AIP) and $HNO_3$. Boehmite sol was coated on a microfiltration(MF) support using the dip-coating method. MF support was dipped into the boehmite sol with a withdrawal speed of 5 mm/s and was maintained for 10 s in the boehmite sol, resulting in a uniform UF membrane layer of $10{\mu}m$ thickness. The porosity of the obtained membrane was measured and found to be 41.2%; the pore size was found to range from 80~100 nm, corresponding to the pore size of the UF membrane. The flux of the obtained membrane was initially 540 $L/m^2h$ and approximately 85% of the initial flux was recovered using a periodic back-flushing process.

• 상하수도학회지
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• 제33권6호
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• pp.437-446
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• 2019

Reverse osmosis seawater desalination facilities can extend the cleaning cycle and replacement time of the reverse osmosis membrane by pretreatment process. Selection of pretreatment process depends on water quality. It was attempted in this study to select approriate pretreatment process for the Masan bay, which was high in particles and organic content. For this purpose, performances of pretreatment processes such as filter adsorber (FA), pore controllable fiber (PCF), and ultrafiltration (UF) were compared based on the silt density index (SDI). The SDI value of the filtrate should be less than 3. The study results showed that UF can produce the filtrate quality satisfying the requirement. However, the transmembrane pressure (TMP) of UF increased quickly, reaching 0.6 bar within 4 days. In order to secure stable operation, FA and PCF were combined with UF. The study results showed that combination of PCF and UF was able to extend the filtration duration (more than 2 months) until to reach TMP of 0.6 bar.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 제5회 하계 Workshop (97 한,카 국제공동 Workshop, 고도 수처리를 위한 막분리 공정)
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• pp.105-142
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• 1997

We know very well the importance of water. Recently, we perceive the truth that water influence the quality of products and we must pay for it. Besides, we recognize why the water treatment is indispensable for life as well as industries. The variation of environment changes the natural resources and threatens the human life. Now, we cannot get water freely from nature. We should find new processes which are effective and inexpensive. We believe that the membrane technology can suggest the new way of water treatment. I'd like to explain the situation of water resource and the membrane processes by UF/MF membranes. I'll also introduce several case studies in this lecture. Till now, about 10 MF/UF systems were established in Korea. Of course, the usage of MF/UF for water treatment is beginning stage in Korea. But the future prospect is very good. Korean government has been developed various kinds of membrane processes for the purpose of drinking water, water reuse, development of new water resources and water related technologies, etc. In near future, maybe we will meet serious water problems, water deficiency and contamination. Fortunetely, we can suggest the membrane process for solving those problems. Membrane technology will be the base of clean technology.