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단일벽 탄소나노튜브의 미량유해물질 흡착거동에서 양이온 계면활성제의 영향에 관한 연구
허지용,이희범,한종훈,손미향,허남국 대한상하수도학회 2014 상하수도학회지 Vol.28 No.4
Recent studies have been reported the presence of Endocrine Disrupting Compounds, Pharmaceuticals and Personal Care Products (EDC/PPCPs) in surface and wastewater, which could potentially affect to the complicate behavior in coupled presence of nano-colloid particles and surfactants (adsorption, dispersion, and partitioning). In this study, the adsorption of EDC/PPCPs by Single Walled Carbon Nanotubes (SWNTs) as a representative of nano-particles in cationic surfactant solutions were investigated. Hydrophobic interactions (π-π Electron Donor-Acceptor) have been reported as a potential adsorption mechanisms for EDC/PPCPs onto SWNTs. Generally, the adsorptive capacity of the relatively hydrophobic EDC/PPCPs onto SWNTs decreased in the presence of cationic surfactant (Cetyltrimethyl Ammonium Bromide, CTAB). This study revealed that the competitive adsorption occurred between CTAB cations and EDC/PPCPs by occupying the available SWNT surface (CTAB adsorption onto SWNTs shows five-regime and maximum adsorption capacity of 370.4 mg/g by applying the BET isotherm). The adsorption capacity of 17α-ethinyl estradiol (EE2) on SWNT showed the decrease of 48% in the presence of CTAB. However, the adsorbed naproxen (NAP) surely increased by forming hemimicelles and resulted in a favorable media formation for NAP partition to increase SWNTs adsorption capacity. The adsorbed NAP increased from 24 to 82.9 mg/g after the interaction of CTAB with NAP. The competitive adsorption for EDC/PPCPs onto SWNTs is likely to be a key factor in the presence of cationic surfactant, however, NAP adsorption showed a slight competition through CH3-CH3 interaction by forming hemimicelles on SWNT surface.
포화 컬럼실험에서 이온강도 변화 및 유기물질 출현에 의한 PVP로 코팅된 은나노 입자의 거동 연구
허지용,한종훈,허남국 대한상하수도학회 2016 상하수도학회지 Vol.30 No.3
Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and CaCl2 solutions) to DI conditions, but in much lower ionic strength (IS) with CaCl2. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and CaCl2 solutions.
클라우드 도입이 서비스 연속성에 미치는 영향에 관한 사례 분석 - 장애 중심으로
허지용,윤준희,한은경 한국인터넷방송통신학회 2023 한국인터넷방송통신학회 논문지 Vol.23 No.4
As service utilization for IT technologies such as artificial intelligence, big data, and IOT has recently increased, cloud computing has been introduced to efficiently manage vast amounts of data and IT infrastructure resources that process them to provide stable and reliable information services while streamlining infrastructure costs. Efforts for this are ongoing. This thesis compares and analyzes the operation results before and after cloud adoption in terms of system failures for 426 systems at 360 branches nationwide in cloud systems of companies operating a total of 1,750 cloud systems. As a result of the analysis, the number of failures and failure types , service downtime, etc., the introduction of the cloud yielded significant results in securing service continuity. Through this result, it is expected to provide meaningful implications to companies expecting to secure service continuity by adopting the cloud
정삼투 멤브레인 공정에서 칼슘이온과 용존 유기물 상호작용에 의한 플럭스 변화 연구
허지용,한종훈,김예진,허남국 대한상하수도학회 2016 상하수도학회지 Vol.30 No.6
The investigation of effects on fouling propensity with various viscosity of feed solutions would be better understanding for forward osmosis (FO) performance since the fouling propensity was directly influenced with solution viscosity. Therefore, this study was focused on the FO fouling with model foultants (humic acid, alginate) by altering solution viscosity with change of ionic strength (I.S) and Ca2+ concentrations. In the comparison between humic acid and alginate, as expected, the alginate generally caused more severe fouling (almost 35.8 % of flux reduction) based on the solution characteristics (high viscosity) and fouling patterns (coil and gel layer). However, interesting point to note is that the fouling propensity of alginate was more severe even though it was applied with low viscosity of feed conditions (I.S = 20 mM, Ca2+ = 1 mM). This might be due to that crossed linked gel layer of alginate on the FO membrane surface could be best formed in the condition of Ca2+ presence and higher I.S, and that is more dominant to fouling propensity than the low viscosity of feed solutions.
지표수 조건의 나노여과공정에서 파울링 및 스케일링이 화약류 물질 잔류에 미치는 영향 연구
허지용(Jiyong Heo),한종훈(Jonghun Han),이희범(Heebum Lee),이종열(Jongyeol Lee),허남국(Namguk Her) 한국지반환경공학회 2015 한국지반환경공학회논문집 Vol.16 No.4
나노여과공정에서 폭발 오염물질인 TNT(2, 4, 6-Trinitrotoluene), RDX(Hexahydro- 1, 3, 5- trinitro- 1, 3, 5- triazine) 및 HMX(1, 3, 5, 7-Tetranitro-1, 3, 5, 7-tetrazocane) 화약류의 잔류에 용존유기물의 오염과 무기물의 스케일링에 의한 케익층 형성 및 농도분극의 영향성을 분석하였다. 지표수 조건의 휴믹산 농도에 의한 나노여과공정에서는 용존유기물에 의한 나노여과막 오염이 발생되어도 플럭스의 큰 변화가 없는 것으로 나타났으며, 휴믹산과 무기 스케일링이 동시에 발생되었을 경우에는 나노여과공정에서 플럭스의 감소가 큰 것으로 나타났다. 휴믹산과 Ca₃(PO₄)₂을 혼합하였을 때 플럭스 투과량이 42% 감소하였고 휴믹산만 첨가하였을 경우에 플럭스 투과량은 8% 감소한 것으로 나타났다. 이는 NF 막의 Ca₃(PO₄)₂ 스켈턴트 결정과 용존유기물이 칼슘(Ca<SUP>2+</SUP>)이온의 상호작용에 의해 막 표면에 증강된 케익층을 형성하여 NF 막의 플럭스를 감소시키는 것을 알 수 있었다. 그리고 막의 크기배제에 의한 선택성을 기반으로 하여 폭발물의 나노여과막에 의한 잔류량을 조사할 경우 HMX(296.15, 83%) ≫ RDX(222.12, 49%) ? TNT(227.13, 32%)로 나타났다. 막 오염과 스케일링은 케익층의 형성으로 막 표면에서 증대된 농도 분극효과를 나타낼 수 있으나, 무기 스케일링형성과 휴믹산에 의한 화약류의 잔류 영향성은 순수한 DI 및 NaCl 피드용액의 여과공정 결과와 크게 다르지 않는 것으로 나타났다. 이는 전량여과방식(Dead-end Flow)의 나노여과공정에서 화약류의 잔류 영향성은 임계크기에 의한 선택적 배제성이 케익층 형성 및 농도분극에 의한 잔류 영향성보다 크다는 것을 보여준다. The combined impact of Dissolved Organic Matter (DOM) fouling and inorganic (CaSO₄,Ca₃(PO₄)₂) scaling on the retention of TNT (2, 4, 6-Trinitrotoluene), RDX (Hexahydro- 1, 3, 5- trinitro- 1, 3, 5- triazine) and HMX (1, 3, 5, 7-Tetranitro-1, 3, 5, 7-tetrazocane) explosive contaminants by nano-filtration membrane were studied, since organic fouling and salt scaling are the major limitations for membrane filtration. Results reported here indicate that DOM fouling layer with a humic acid does not necessarily lead to an immediate loss of permeate flux but can result in a severe impact on the flux loss when both humic acid and inorganic scaltants were presented simultaneously. The Ca₃(PO₄)₂ mixed with humic acid showd most sever flux loss (42%) compared to that of only humic acid presence (8%). It could be a result that the scaling formation of the NF membrane was dominated by cake layer formation of DOM and it was along with pore blocking by the formation of crystals inside the porous active matrix of the NF membrane. In addition, these results indicated that the membrane selectivity of the explosives retention trended correlated with respect to increasing explosives size (listed by MW) based on greater steric interactions and followed the order (MW, g mol<SUP>-1</SUP>; removal, %): HMX (296.15; 83%) >> RDX (222.12; 49%) ? TNT (227.13; 32%). Because the scaling and fouling layer could lead to a additional cake-enhanced concentration polarisation effect, the retention of explosives with the presence of humic acid in the feed solution and inorganic scaling formation on top of an organic fouling layer do not differ substantially retention from that of pure DI feed and NaCl solution.