• Journal of Korean Society of Water and Wastewater
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• v.33 no.6
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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.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.311-319
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• 1999

Membrane separation process is considered as an alternative of conventional water purification system using coagulationㆍsedimentation＋sand filtration. In this study, it was examined that the application possibility of Hollowfiber Microfiltration membrane for water purification process. A $20m^3/day$ scale pilot plant was used for studying the possibility of long-term operation and the stability of water quality under the optimum conditions, 0.03m/h permeate flux, filtration for 10 minutes, pause for 2 minutes(including air-scrubbing for 30 seconds), obtained by lab-scale experiment. As a result, it was proved stability of pilot plant over one year and filtrate quality(Turbidity. SS etc). Therefore, it was proved that membrane separation process using Hollowfiber Microfiltration membrane can be applied for water purification system

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.62-67
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• 2014

A glomerular filtration rate (GFR) study is a test that uses radioactive materials or tracers (radiopharmaceuticals) and a computer to see how well the kidneys are working. Asan Medical Center analyzed and compared data between kidney depth, acquired from kidney donors' CT image and acquired from Gates method's GFR value that are calculated by Tonnesen equation. This study was able to confirm that kidney depth measured from CT image was higher than the Gates Method's GFR value, which was calculated by Tonnessen equation; the direct relationship among pathologic results is confirmed. Particularly, kidney donor whose kidney was at the pelvic area had direct relationship with other clinical results. During the GFR test, it is necessary to confirm the location of kidney has no change with reference of CT image. If kidney depth is manually corrected using CT image when we measures GFR of deformed or horse-shoe kidney, it would be possible to acquire the compatible value which is equivalent to clinical result. There would be a possible issue of appropriateness that whether the applied GFR using CT image's kidney depth has clinical validity. In case of a pediatric patient, the GFR derived from Tonnesen was quiet underestimated while manual method and Gordon stay in normal range. Which results may be correct among them? There have been many reports about kidney depth, to be an accurate index of GFR in children. As one of the study performers, we should contemplate what the best option for pediatric patients would be.

• Membrane Journal
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• v.19 no.2
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• pp.165-171
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• 2009

This study was for the evaluation of adaptability of the fiber filter as the pre-treatment of the RO membrane through SDI (Silt Density Index) measurement. The turbidity of raw waters were $0.76{\sim}1.6$ NTU for the effluent of sewer treatment plants (STP) and $2.2{\sim}3.3$ NTU for sea waters and 100 NTU for the surface water. The turbidity of the $2^{nd}$ filtrate of the serially connected two fiber filters was $0.07{\sim}0.25$ NTU and $SDI_{15}$ was $1.4{\sim}2.8$ when the 17% PAC was dosed $10{\sim}30ppm$. Results of the turbidity and $SDI_{15}$ of the $2^{nd}$ filtrate of the fiber filter which were compared with them of the lab scale MF/UF disc filter for the same STP's effluents showed that filtrate quality were enhanced with a little on the order of two stage fiber filter>MF>UF, the difference in $SDI_{15}$ was only $0.7{\sim}1.0$. So, the filtrate of the serially connected two stage fiber filter could satisfy $SDI_{15}$ 5.0 safely which was normally required for the feed water by the RO membrane supplier and it means the serially connected two stage fiber filter could be applied as the pre-treatment process of the RO membrane.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.323-330
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• 2014

Image reconstruction is one of the most important processes in CT (Computed tomography) technology. For fast scanning and low dose to the objects, iterative reconstruction is becoming more and more important. In the implementation of iterative reconstruction, projection and backprojection processes are considered to be indispensable parts. However, many approaches for projection and backprojection may result severe image artifacts due to their discrete characteristics and affects the reconstructed image quality. Thus, new approaches for projection and backprojection are highly demanded these days. In this paper, distance-driven approach was evaluated and compared with other conventional methods. The numerical simulator was developed to make the phantoms, and projection and backprojection images were compared using these approaches. As a result, it turned out that there are less artifacts during projection and backprojection in parallel and fan beam geometry.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.40-42
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• 1997

수처리 공정의 목적은 원수 중에 포함된 콜로이드, 미립자 등의 현탁물질, 이온과 유기물 등의 용해성 물질의 제거로, 이러한 목적을 위해서 수처리공정에 막분리 기술을 이용하는데 관심이 높아지고 있고, 이미 일부에서는 실용화되었다. 분리막에는 분리막의 기공의 크기에 따라 역삼투막, 한외여과막, 정밀여과막이 있으며, 대상 폐수 및 처리수의 재활용 여부에 따라 선정하여 사용한다. 본 연구에서는 폴리설폰 재질의 중공사하여 한외여과막을 사용하여 하천수를 처리하여 투과수와 원수의 수질을 비교함으로써, 분리막 기술에 의한 하천수처리의 타당성 및 처리 효율을 고찰해 보고자 하였다. 대상 원수로 최근 생활하수의 유입으로 수질이 악화되고 있는 소양강의 한 지류인 공지천의 물을 사용하였다.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.76-78
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• 2001

먹는 물에 존재하는 크립토스포리디움 및 지아디아등 기존의 표준 정수처리 공정에 의해 제거가 용이치 않은 원생동물 둥을 채집할 수 있는 미생물 검출 캡슐을 개발하였다. 본 장치의 여과필터는 고분자물질을 소재로 한 중공사 형태(Hollow Fiber Membrane)로 유효여과면적을 크게하였고, Pore size는 0.1㎛이다. 채집캡슐은 탁도에 따른 투과수량은 일차의 상관관계를 나타내며, 시간당 20ℓ를 투과시킬 때 탁도 7.0 NTU까지 가능함을 확인 할 수 있었다. 일차 시제품은 89.6-94.6%의 크립토스포리디움 및 72.6-78.6%의 지아디아 포낭을 회수하였고, 이차 시제품은 92.5-93.7%의 크립토스포리디움 및 81.3-88.2%의 지아디아 포낭을 회수하는 것으로 나타났다. 동일한 조건에서 외국제품은 84.0%의 크립토스포리디움 및 66.7%의 지아디아 포낭을 회수하는 것으로 나타났다.

• Membrane Journal
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• v.25 no.3
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• pp.256-267
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• 2015

The goal is to compare two different aeration strategies for a pilot scale operation of submerged microfiltration with respect to the minimization of membrane fouling. A constant aeration (65 L/min) was examined parallel with a step-wise increase in airflow rate (40 to 65 L/min). The airflow rate was stepped to a higher rate every 5 min and the step-aeration cycles were repeated at regular intervals of 15 min. The comparative filtration runs were conducted with synthetic water containing powdered activated carbon (~10 g/L) and/or kaolin (~20 g/L) at a constant flux of 80 LMH. The extent and mechanisms of fouling in the microfiltration were identified by determining hydraulic resistance to filtration and the fouling reversibility after cleaning. Results showed that the step-aeration effectively alleviated fouling in the microfiltration of synthetic water compared to when using constant aeration. A substantial decrease in fouling was achieved by combining with coagulation using aluminum salts regardless of the aeration strategies. The constant aeration resulted in increased pore blocking likely due to increased accumulation of particles on the surface of membrane.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.67-78
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• 2005

Riverbank filtration has been used in advanced countries for 150 years. In Korea, investigations for producing riverbank filtrate started in the Han River, Nakdong River, Geum River, Yeongsan River and Seomjin River basins in the 1990s. The lower part of the Nakdong River has a poorer water quality than the upper part of the river. A water balance analysis and groundwater flow modeling were conducted for the riverbanks of the Nakdong River in Daesan-Myeon, Changwon City. The results of the water balance analysis revealed the groundwater infiltration rate into the aquifer to be 245.26 mm/year (19.68% of the average annual precipitation, 1,251.32 mm). Direct runoff accounts for 153.49 mm/year, evapotranspiration is 723.95 mm/year and baseflow is 127.63 mm/year. According to the groundwater flow modeling, 65% of the total inflow to the pumping wells originates from the Nakdong River, 13% originates from the aquifer in the rectilinear direction, and 22% originates from the aquifer in the parallel direction. The particle tracking model shows that a particle moving from the river toward the pumping wells travels 100 m in 50 days and a particle from the aquifer toward the pumping wells travels 100 m in 100 days.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.73-78
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• 2012

In this study, three different synthetic musk compounds (SMCs) in the Nakdong river water (raw water) and rapid sand filtered water were treated by $O_3$ process. The experimental results showed that the removal efficiency of musk ketone (MK) was lower than removal efficiency of AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[c]-2-benzopyran) for both the raw water and the rapid sand filtered water. And in general, the removal efficiencies of three SMCs in the raw water were lower than that in the sand filtered water. Under the $O_3$ dose of 0.5~10.0 mg/L, the removal rate constants (k) of three SMCs for the raw and sand filtered waters increased rapidly with the increased $O_3$ dose. In the case of drinking water treatment plants (DWTPs) which were selected pre- and post-$O_3$ processes (located in the downstream of Nakdong River), operation conditions of pre- and post-$O_3$ process were $0.5{\sim}2.0mg{\cdot}O_3/L$ (2~4 min) and $0.5{\sim}2.5mg{\cdot}O_3/L$ (6~8 min). Therefore, $O_3$ doses and contact times of same conditions with above were very difficult to remove SMCs in DWTPs.