• Journal of Korea Water Resources Association
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• v.49 no.9
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• pp.741-748
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• 2016

Laboratory scale model was constructed for open-cut riverbed infiltration experiment and four kinds of media were selected, medium sand, sand, volcanic rock, and gravel, for the experiment. Hydraulic conductivity for each medium and flow rate from the collecting pipe with functional screen were estimated from the experiment. Modified hydraulic conductivity scenarios considering turbid water (30~50 NTU) were applied in Visual MODFLOW modeling to analyze the effects of turbid water on the flow rate. Twenty-two scenarios were generated considering prticles in turbid water and applied to each medium cases in MODFLOW modeling. The minimum error was occurred when the gravel medium had 20% less hydraulic conductivities for the third layer-depth from the top and clay particles in turbid water might play a role in adsorption process to the surface of volcanic rock (2~5 mm). For medium sand case the error was also quite small when the mediumhas 5% less hydraulic conductivities for the second layer-depth from the top.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.359-364
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• 2012

In order to prevent the decrease in well efficiencies due to friction in the axial flow in long, large-diameter laterals, a multi-diameter lateral was devised and tested through lab-scale sand-box experiments to assess its performance. In the experiment, three different production rates were applied over the multi-diameter and the three single-diameter laterals to obtain the hydraulic head distributions for each, which was used to assess the performance of the laterals. Results elucidated that the multi-diameter lateral reduced the material cost by more than a third, in comparison to the single-diameter lateral, while maintaining the production rate at higher than 93%, proving its superiority. Furthermore, results indicated that exit velocities exceeding 0.8 m/sec in horizontal wells tended to distort the hydraulic head distribution near the exit, providing evidence of its inefficiency.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.469-472
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• 1998

상업적으로 유용한 대부분의 합성고분자막들은 상전환법(phase inversion process)이라는 방법에 의해서 제조된다. 이 제조공정에서는 단일 고분자(homogeneous polymer)용액에 존재하는 용매를 비용매와 교환함으로써 액체로부터 고체로 상이 전환된다. 그리고 pore의 크기나 pore의 크기분포와 같은 막의 구조를 결정하는 요인은 일반적으로 용질의 입자크기 또는 분자크기 및 화학적 성질에 기인한다[1-3]. (중략)

• Membrane Journal
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• v.20 no.2
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• pp.97-105
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• 2010

This study was to evaluate the performance of the Double stage Pore controllable fiber (DP) filter system as the pre-treatment of the RO membrane. The evaluation for the pre-treatment filter was performed through the indirect method, SDI (Silt Density Index) measurement of the filtrate. This study was done during Jan. 3 of 2009 to Dec. 3 of 2009 at OO Water Treatment Plant that was suppling industrial water to plants, and the raw water was contaminated lake water and it was fed to the system after clarification with coagulation. The average turbidity of the feed water and that of the filtrate was 0.79 NTU (0.28~4.01 NTU), and 0.16 NTU (0.04~0.50) respectively. And so the average turbidity removal efficiency was 77%. The filtrate flow rate and the backwash water flow rate was about 230 $m^3$/day and about 8.7 $m^3$/day respectively, and so the backwash rate was 3.8%. The data for some samples were obtained after a few days storage, and it caused the higher turbidity and SDI15 as the storage time was increased. But average SDI value of the filtrate was 3.6 (2.26~5.00) which was lower than minimum value required by the RO membrane manufacturer as the RO feed water to guarantee the life time of the RO membrane. So, the DP filter system was enough for the application as the pre-treatment of the RO membrane.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.503-508
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• 2007

Small scale D-water treatment plant(WTP) where has slow sand filtration was using raw water containing high concentration of manganese (> 2mg/l). The raw water was pre-chlorinated for oxidation of manganese and resulted in difficulty for filtration. Thus, sometimes manganese concentration and turbidity were over the water quality standard. Two stage rapid manganese sand filtration pilot plant which can treat $200m^3/d$ was operated to solve manganese problem in D-WTP. The removal rate of manganese and turbidity were about 38% and 84%, respectively without pH control of raw water. However, when pH of raw water was controlled to average 7.9 with NaOH solution, the removal rate of manganese and turbidity increased to 95.0% and 95.5%, respectively and the water quality of filtrate satisfied the water quality standard. Manganese content in sand was over 0.3mg/g which is Japan Water Association Guideline. The content in upper filter was 5~10 times more than that of middle and lower during an early operation but the content in middle and lower filter was increased more and more with increase of operation time. This result means that the oxidized manganese was adsorbed well in sand. Rapid manganese sand filter was backwashed periodically. The water quality of backwash wastewater was improved by sedimentation. Thus, turbidity and manganese concentration decreased from 29.4NTU to 3.09NTU and from 1.7mg/L to 0.26mg/L, respectively for one day. In Jar test of backwash wastewater with PAC(Poly-aluminum chloride), optimum dosage was 30mg/L. Because the turbidity of filtrate was high as 0.76NTU for early 5 minute after backwash, filter-to-waste should be used after backwash to prevent poor quality water.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.3
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• pp.113-122
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• 2008

In RFID system, Middleware collects and filters streaming data gathered continuously from readers to process applications requests. The enormous amount of data makes middleware in highly overloaded. Hence, we propose reader level filtering in order to reduce overall middleware load. In this paper, we consider reader filtering capability and define query plan to minimize number of queries for processing into middleware and reader level. We design and implement middleware system based on proposed query plan. We perform several experiments on implemented system. Our experiments show that the proposed query plan considerably improves the performance of middleware by diminishing processing time and network traffic between reader and middleware.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.878-883
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• 2006

Removal efficiency of As(III) was investigated with a pilot-scale filtration system packed with an equal amount(each 21.5 kg) of manganese-coated sand(MCS) in the bottom and iron-coated sand(ICS) in the top. Height and diameter of the used column was 200 cm and 15 cm, respectively. The As(III) solution was introduced into the bottom of the filtration system with a peristaltic pump at a speed of $5{\times}10^{-3}$ cm/s over 148 days. Breakthrough of total arsenic in the mid-sampling position(end of the MCS bed) and final-sampling position(end of the ICS bed) was started after 18 and 44 days, respectively, and then showed a complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position was started after 18 days, the concentration of As(III) in this effluent was below 50 ppb up to 61 days. This result indicates that MCS has a sufficient oxidizing capacity to As(III) and can oxidize 92 mg of As(III) with 1 kg of MCS up to 61 days. When a complete breakthrough of total arsenic occurred, the removed total arsenic by MCS was calculated as 79.0 mg with 1 kg MCS. As variation of head loss is small at each sampling position over the entire reaction time, it was possible to operate the filtration system with ICS and MCS for a long time without a significant head loss.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.740-743
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• 2010

미량의 바나듐을 함유하고 있는 제주도 지하수를 나노여과(nanofiltration) 공정을 이용하여 바나듐을 고농도로 농축하고, 그 농축수를 이용하여 기능성 녹차를 제조하였다. 원수와 4단, 6단 농축한 물의 바나듐 함량은 각각 10.4, 21.6 및 31.7ppb 이었다. 이 농축수들을 이용하여 녹차 제조를 한 결과 바나듐과 카테킨 함량이 감소함을 알 수 있었다. 녹차 추출 전후의 바나듐 함량 감소율은 여름녹차의 경우에는 36.3% - 40.8%, 가을녹차의 경우에는 22.4% - 41.4%이었다. 이는 녹차잎을 이용하여 녹차를 제조하는 과정에서 바나듐 성분이 녹찻잎으로 흡착된 것으로 보이며, 녹차의 카테킨 성분은 이온함량이 높은 물에서는 잘 용출되지 않는다는 것을 확인할 수 있었다.

• Journal of Korean Society of Disaster and Security
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• v.12 no.1
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• pp.23-34
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• 2019

It is an urgent issue to manage and reduce non-point pollution sources for improving the water quality of stream and lakes in rural areas. In this study, in order to reduce non-point pollution sources in rural area, Gabion mattresses was proposed to provide protection of riverbanks with anaerobic and aerobic area. The utilization of this was assessed by lab scale model test and pilot plant test. After filling the inside of the gabion mattresses with aggregate, the filtration zone under anaerobic and aerobic conditions was formed to treat the contaminants. In addition, vegetation was deposited on the surfae of the gabion to prevent the inflow of soil and to promote purification by the plant. COD and nitrogen content (T-N, $NH_4{^+}$, -N, $NO_3{^-}N$) were monitored in model and field tests. The lab scale model test showed removal efficiency of 17% of TCOD, 35% of SCOD, 14% of TN, 62% of $NH_4{^+}$, -N, and 33% of $NO_3{^-}$ N. Also, pilot plant test showed removal efficiency of 24% of TCOD, 29% of SCOD, 47% of TN, 50% of $NH_4{^+}-N$, 33% of $NO_3{^-}$, N and 29% of TP.

• 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