• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2000년도 학술발표회 논문집
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• pp.848-850
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• 2000

• 상하수도학회지
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• 제23권1호
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• pp.121-128
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• 2009

Objectives of this study were to investigate influencing factors of detention time, particle size distribution, and filter medium characteristics for waterworks sludge dewatering. The stepped pressure filtration was carried out with lab scale apparatus and the filter press pilot test for dewatering was conducted at the water treatment plant. Effects of filter medium and polymer dose were examined through observing water content and dewatering velocity and cyclic dewatering rate with filter press pilot test. Relationships among detention time, particle size distribution and filtration resistance were analyzed. Prolongation of sludge detention time was found to cause blinding phenomenon in cake and filter medium and to decrease dewatering process efficiency. The average specific resistance increased according to detention time. In pilot test of dewatering for thickened sludge with Nylon Multi-NY840D and Nylon Mono-100% filter media, dewatering velocities were 0.92 and $0.93kg\;DS/m^2{\cdot}hr$ according to 0.1% polymer dose of dried solids weight base. And cyclic dewatering rates were 2.45 and $2.50kg\;DS/m^2{\cdot}cycle$ cycle for the Nylon Multi-NY840D and Nylon Mono-100% media. Dewatering velocity of polymer dosed sludge was observed to be higher than that of non-polymer sludge.

• 한국인공지능학회지
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• 제12권2호
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• pp.9-16
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• 2024

In this study, we delve into the effects of personalization algorithms on the creation of "filter bubbles," which can isolate individuals intellectually by reinforcing their pre-existing biases, particularly through personalized Google searches. By setting up accounts with distinct ideological learnings-progressive and conservative-and employing deep neural networks to simulate user interactions, we quantitatively confirmed the existence of filter bubbles. Our investigation extends to the deployment of an LSTM model designed to assess political orientation in text, enabling us to bias accounts deliberately and monitor their increasing ideological inclinations. We observed politically biased search results appearing over time in searches through biased accounts. Additionally, the political bias of the accounts continued to increase. These results provide numerical evidence for the existence of filter bubbles and demonstrate that these bubbles exert a greater influence on search results over time. Moreover, we explored potential solutions to mitigate the influence of filter bubbles, proposing methods to promote a more diverse and inclusive information ecosystem. Our findings underscore the significance of filter bubbles in shaping users' access to information and highlight the urgency of addressing this issue to prevent further political polarization and media habit entrenchment. Through this research, we contribute to a broader understanding of the challenges posed by personalized digital environments and offer insights into strategies that can help alleviate the risks of intellectual isolation caused by filter bubbles.

• 상하수도학회지
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• 제29권3호
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• pp.337-345
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• 2015

Two step rapid filter system as a pre-treatment for the injected water into aquifer storage and recovery (ASR) in Korea was developed to reduce physical blockage and secure the volume of the injected water. First, single rapid sand filters with three different media sizes (0.4~0.7, 0.7~1.0 and 1.0~1.4 mm) were tested. Only two sizes (0.4~0.7 and 0.7~1.0 mm) satisfied target turbidity, below 1.0 NTU. However, they showed the fast head loss. To prevent the fast head loss and secure the volume of the injected water, a rapid anthracite filter with roughing media size (2.0~3.4 mm) were installed before a single rapid sand filter. As results, both the target turbidity and reduction of head loss were achieved. It was determined that the media size for a rapid sand filter in two step rapid filter system (i.e. a rapid anthracite filter before a rapid sand filter) was 0.7~1.0 mm. In addition, the effects of coagulant doses on the removal of natural organic matter (NOM), which might cause a biological clogging, were preliminarily evaluated, and the values of $UV_{254}$, dissolved organic carbon (DOC) and SUVA were interpreted.

• 한국양식학회지
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• 제18권4호
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• pp.280-286
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• 2005

순환여과 사육시스템에서 유동층 여과조의 적정 유동조건을 구명하기 위하여 메디아 유동을($50\%,\;100\%$), 수은($15^{\circ}C,\;25^{\circ}C$) 및 암모니아 부하량(2 mg/L, 5 mg/L) 차이에 따른 암모니아 제거율을 조사하였다. 유동층 여과 시스템은 직경 8.3 cm, 높이는 2.0 m의 원통형으로 상부는 여과재료의 유동 비율의 조절이 용이하며 육안적으로 관찰이 가능한 아크릴관을 이용하였고 하부는 PVC 재질로 제작하였다. 유동층 여과 시스템의 여과 메디아로 직경 0.5$\pm$0.1mm 크기의 모래와 제올라이트 입재를 각각 5.4 L씩 여과조에 넣었다. 유동층 여과조의 암모니아 제거 능력은 암모니아 부하량에 따라 부하량이 적은 2 mg/L 실험구에 비해 부하량이 큰 5 mg/L실험구에서 암모니아 제거 효율이 높았고, 여과 메디아 별로는 제올라이트 메디아가 모래 메디아에 비해 암모니아 제거율이 높았다. 수은에 따른 유동층 여과 시스템의 암모니아제거 능력은 수은이 높은 $25^{\circ}C$ 가 수온이 낮은 $15^{\circ}C$에 비해 암모니아 제거율이 높았으며, 메디아의 유동율에 따른 유동층 여과조의 암모니아 제거율은 유동을 $50\%$가 유동을 $100\%$에 비해 높았다. 이상의 결과로부터 유동층 여과조의 운용조건이 수온 $25^{\circ}C$, 암모니아부하량이 5 mg/L이고 여과메디아의 유동율이 $50\%$일 때, 유동층 여과조의 일간 암모니아 제거량은 $80.6{\~}210.6g/m^3$으로 산정되었다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.173-176
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• 2002

With the introduction of high-tech industries, these days textile products used as advanced materials of semiconductor, transport and medical fields. It was concerned with environmental problem in textile industry lately. So the problem is receiving careful study for high effectiveness and high efficiency of filter media made by nonwoven fabric to get rid of a pollutant. PET filter media produced from conventional methods can not precisely filtrate small particles, because conventional PET filter media has too large pore size. (omitted)

• 한국물환경학회지
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• 제22권3호
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• pp.456-461
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• 2006

The facility of constructed wet land combined with filter media was examined in order to improve the water quality of a polluted stream, which has been performed as a part of national projects. Throughout 2 years of operation for a stream, it can provide the design and operating parameters for the purpose of future construction. The influent flow rate was about 50% against the design capacity. The removal efficiencies of BOD, $COD_{Mn}$, SS, T-N and T-P were 62.9%, 47.1%, 74.8%, 22.4% and 33.5%, respectively. In order to keep this facility stable, the removal of surface filter media and supplement should be periodically conducted. In addition, the proper selection of sites is recommended not to be flooded.

• 상하수도학회지
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• 제21권6호
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• pp.763-770
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• 2007

There are many design parameters affecting filtration efficiency such as filteration rate, media packing depth, size distribution, and so on. The sphericity, the ratio of the surface area of an equal volume sphere to the real surface area of the particles, is one of major physical characters of media. The effect of sphericity on the performance of anthracite filter has been investigated. Media from eight water treatment plants have been collected. The sphericity of each media has been calculated by using well known headloss equations such as Kozeny equation, Dahmarajah equation etc.. Columns packed with anthracite media having different sphericity have been used to compare headloss development, floc accumulation in the bed, particles in bed water, filtrate turbidities after backwash and so on. The repeated experiments have indicated that the sphericity of anthracite media may not have remarkable influence on the filter performance as it has been suspected. It also has been prospected in the experiment that the media of higher sphericity would store more particles in the bed and give better filtrate quality, if provided that the effective size and the size distribution of media would be the same.

• 한국수산과학회지
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• 제20권6호
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• pp.561-567
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• 1987

순환 여과식 양식에 있어서 사육수에 축적되는 암모니아를 여과 재료별로 그 제거 능력을 알아보고, 실제 산업에의 적용에 관한 문제를 검토하였다.. 여과 재료는 첨모직(pile cloth), 스카이 라이트 골판(corrugated skylight roofing plate), 요철 플라스틱판(embossed plastic plate), 및 자갈의 4종류를 사용, $90cm\times60cm\times60cm$(깊이)의 수조에 각각 2개씩 같은 재료를 넣어서 모두 8개를 설치하였다. 주입수는 부산수산대학 순환여과식 양식 시설의 어류사육 탱크에서 나오는 물을 사용하여 그 속에 함유된 암모니아 제거능력을 측정하였다. 정상적 기능을 발휘하는 두 기간의 여과 재료별 1일 $1m^3$의 여과제 설치 용적당 평균 암모니아 제거 능력은 다음과 같았다. 1) 첨모직 8.381g 2) 2) 스카이 라이트 골판 7.834g 3) 요철 플라스틱판 7.797g 4) 자갈 7.051 g 이와 같이 주기능 발휘 기간동안에는 재료별 차이가 별로 없었지만 그 기간의 길이 차이, 청소의 난이도, 설치 비용 등을 고려해야 한다. 특히 대형 여과조의 경우, 자갈 여과조를 청소하는 일은 대단히 어렵고, 첨모직 여과조는 그 설치 작업이 까다롭고, 배수시 그 구조를 유지하는 데 어려운 문제가 따른다. 이러한 관점에서 볼 때 스카이 라이트 곡판과 요철 플라스틱판이 가장 적당하다고 생각된다. 그러나, 실제 설치시는 재료의 입수 가능성, 가격은 물론, 사용중 또는 계획중의 여과 탱크에의 적합 여부도 고려되어야 한다.

• 방송과미디어
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• 제7권3호
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• pp.65-74
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• 2002