• 한국환경보건학회지
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• 제39권5호
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• pp.391-407
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• 2013

Micropollutants emerge in surface water through untreated discharge from sewage and wastewater treatment plants (STPs and WWTPs). Most micropollutants resist the conventional systems in place at water treatment plants (WTPs) and survive the production of tap water. In particular, pharmaceuticals and endocrine disruptors (ECDs) are micropollutants frequently detected in drinking water. In this review, we summarized the distribution of micropollutants at WTPs and also scrutinized the effectiveness and mechanisms for their removal at each stage of drinking water production. Micropollutants demonstrated clear concentrations in the final effluents of WTPs. Although chronic exposure to micropollutants in drinking water has unclear adverse effects on humans, peer reviews have argued that continuous accumulation in water environments and inappropriate removal at WTPs has the potential to eventually affect human health. Among the available removal mechanisms for micropollutants at WTPs, coagulation alone is unlikely to eliminate the pollutants, but ionized compounds can be adsorbed to natural particles (e.g. clay and colloidal particles) and metal salts in coagulants. Hydrophobicities of micropollutants are a critical factor in adsorption removal using activated carbon. Disinfection can reduce contaminants through oxidation by disinfectants (e.g. ozone, chlorine and ultraviolet light), but unidentified toxic byproducts may result from such treatments. Overall, the persistence of micropollutants in a treatment system is based on the physico-chemical properties of chemicals and the operating conditions of the processes involved. Therefore, monitoring of WTPs and effective elimination process studies for pharmaceuticals and ECDs are required to control micropollutant contamination of drinking water.

• 상하수도학회지
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• 제28권4호
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• pp.397-409
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• 2014

Algal problem in drinking water treatment is being gradually increased by causing deterioration of water supplies therefore, especially taste and odor compounds such as geosmin and 2-MIB occur mainly aesthetic problem by its unpleasant effects resulting in the subsequent onset of complaints from drinking water consumer. Recently, geosmin and 2-MIB are detected frequently at abnormally high concentration level. However, conventional water treatment without advanced water treatment processes such as adsorption and oxidation process, cannot remove these two compounds efficiently. Moreover, it is known that the advanced treatment processes i.e. adsorption and oxidation have also several limits to the removal of geosmin and 2-MIB. Therefore, the purpose of this study was not only to evaluate full scale nanofiltration membrane system with $300m^3/day$ of permeate capacity and 90% of recovery on the removal of geosmin and 2-MIB in spiked natural raw water sources at high feed concentration with a range of approximately 500 to 2,500 ng/L, but also to observe rejection property of the compounds within multi stage NF membrane system. Rejection rate of geosmin and 2-MIB by NF membrane process was 96% that is 4% of passage regardless of the feed water concentration which indicates NF membrane system with an operational values suggested in this research can be employed in drinking water treatment plant to control geosmin and 2-MIB of high concentration. But, according to results of regression analysis in this study it is recommended that feed water concentration of geosmin and 2-MIB would not exceed 220 and 300 ng/L respectively which is not to be perceived in drinking tap water. Also it suggests that the removal rate might be depended on an operating conditions such as feed water characteristics and membrane flux. When each stage of NF membrane system was evaluated relatively higher removal rate was observed at the conditions that is lower flux, higher DOC and TDS, i.e., $2^{nd}$ stage NF membrane systems, possibly due to an interaction mechanisms between compounds and cake layer on the membrane surfaces.

• 한국건설순환자원학회논문집
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• 제9권1호
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• pp.85-91
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• 2021

건설폐기물에서 발생하는 순환골재의 분류 과정에서 발생하는 이물질을 순환골재 출하 전에 회수하기 위하여 회전분리망 흡착 선별기를 설계 및 제작하였다. 제작된 선별기의 성능을 평가하기 위하여, 순환골재에서 자체적으로 회수한 이물질 종류에 따라, 아크릴을 사용하여 규격화된 이물질 샘플을 제작하고, 선별기에서 작동하는 흡입팬의 제어주파수 및 분리망의 흡입구 위치에 따른 선별효율과 순환골재의 오분류율을 평가하여 적절한 운전점을 평가하였다. 순환골재 및 이물질을 입자로 가정한 유동해석을 통해 예측된 선별기의 운전점에서의 분류효율을 평가하였다. 성능 시험 결과 컨베이어 밸트와 흡입구의 거리가 0.2m일 때 95%의 선별효율을 보이는 것으로 나타났으나, 순환골재의 오분류율이 2% 이상으로 선별효율과 2% 이하의 오분류율을 만족하는 운전점은 흡입구 거리 0.254m에서 제어주파수 58Hz으로 나타났다. 유동해석 결과 이물질 선별기에서 순환골재의 오분류는 나타나지 않았다. 기존 순환골재 생산공정에서 이물질 저감을 위해 설치식으로 운용이 가능한 회전분리망을 이용한 풍력 선별시스템을 구축하였다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2004년도 춘계학술발표회
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• pp.81-84
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• 2004

Control of Sediment is very important in prawn farm due to the eruption of toxic material such as W1ionized H2S, NH3 and NO2-. In this study, column test study, column with filter media such as activated carbon, zeolite, oyster shell and iron chloride to evaluate the reduction of toxicity from sediment ammonia-N(NH3) was effectively removed by Zeolite and oyster shell. It was indicated that ammonium ion(NH4+) was removed by ion exchange of zeolite. And the ammonia in the column of oyster shell was existed as the form of NH4+, which is not toxic for prawn because oyster shell was stably kept around pH 8. Therefore, some of ammonia(NH3) was reduced by oyster shell. Hydrogen sulfide and COD were effectively removed by adsorption of activated carbon and a partial removal of hydrogen sulfide was accomplished by Oyster shell. Phosphorous was removed by activated carbon, oyster shell and iron chloride. In prawn farm, the concentration of ammonia was increased with increase of pH by algae photosynthesis in the column of activated carbon, zeolite and iron chloride, but it was revealed that pH was stably kept in the column of oyster shell.

• 대한환경공학회지
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• 제31권10호
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• pp.909-918
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• 2009

급수시스템에서 박테리아 재성장의 영양원이 되는 DOC를 정수처리 공정에서 효과적으로 저감시키기 위하여 생분해와 흡착으로 구분하여 네 종류의 DOC로 분획하였고 각각의 제거특성을 연구하였다. 네 종류의 분획 DOC는 흡착성을 가지면서 생분해성이 없는 AnBDOC, 흡착성이 없고 생분해성만이 있는 nABDOC, 흡착과 생분해성을 동시에 나타내는 ABDOC, 흡착과 생분해가 되지 않는 nAnBDOC로 구분하여 분석하였다. 낙동강 중류에 위치한 정수처리장 원수의 조사결과, ADOC가 BDOC보다 약간 높은 비율로 존재하고 있으며, 오존산화 후에는 분획 DOC 중에서 AnBDOC 농도가 가장 많이 제거되었으며, 제거율은 nAnBDOC가 49.5%로 가장 높았다. BAC 공정으로 제거된 분획 DOC 중에는 ADOC가 약 91%를 차지하고 있으므로 흡착에 의한 제거가 우수한 것으로 나타났고, 잔류하는 TDOC 0.50 mg/L 중에는 ADOC가 0.46 mg/L(67.7%)을 차지하고 있으므로 배수관내 미생물 증식 및 소독부생성물의 생성 방지를 위하여 BAC 공정상에서 EBCT증가, 재생주기 등의 운전조건을 개선해야 하는 것으로 나타났다. 정수처리 공정에서 DOC분획 결과로부터 흡착이나 생분해 등으로 제거 가능량을 파악할 수 있으므로 정수처리 공정에 유용한 것으로 나타났다. 염소처리하는 정수처리 공정에서 DOC분획 농도와 밀접한 관계를 가지는 AOX의 분석결과, AOX 7.1 ${\mu}g$/L은 오존산화와 활성탄흡착 공정으로 0.51 ${\mu}g$/L까지 충분히 제거되었다.

• Carbon letters
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• 제4권1호
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• pp.1-9
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• 2003

Recently, the control of pore-characteristics of nano-porous materials has been studied extensively because of their unique applications, which includes size-selective separation, gas adsorption/storage, heterogeneous catalysis, etc. The most widely adopted techniques for controlling pore characteristics include the utilization of pillar effect by metal oxide and of templates such as zeolites. More recently, coordination polymers constructed by transition metal ions and bridging organic ligands have afforded new types of nano-porous materials, porous metal-organic framework(porous MOF), with high degree and uniformity of porosity. The pore characteristics of these porous MOFs can be designed by controlling the coordination number and geometry of selected metal, e.g transition metal and rare-earth metal, and the size, rigidity, and coordination site of ligand. The synthesis of porous MOF by the assembly of metal ions with di-, tri-, and poly-topic N-bound organic linkers such as 4,4'-bipyridine(BPY) or multidentate linkers such as carboxylates, which allow for the formation of more rigid frameworks due to their ability to aggregate metal ions into M-O-C cluster, have been reported. Other porous MOF from co-ligand system or the ligand with both C-O and C-N type linkage can afford to control the shape and size of pores. Furthermore, for the rigidity and thermal stability of porous MOF, ring-type ligand such as porphyrin derivatives and ligands with ability of secondary bonding such as hydrogen and ionic bonding have been studied.

• Geomechanics and Engineering
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• 제13권5호
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• pp.861-879
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• 2017

Coal and gas outburst is a serious dynamic disaster that occurs during coal mining and threatens the lives of coal miners. Currently, coal and gas outburst is commonly predicted using single indicator and its critical value. However, single indicator is unable to fully reflect all of the factors impacting outburst risk and has poor prediction accuracy. Therefore, a more accurate prediction method is necessary. In this work, we first analyzed on-site impacting factors and precursors of coal and gas outburst; then, we constructed a Fisher discriminant analysis (FDA) index system using the gas adsorption index of drilling cutting ${\Delta}h_2$, the drilling cutting weight S, the initial velocity of gas emission from borehole q, the thickness of soft coal h, and the maximum ratio of post-blasting gas emission peak to pre-blasting gas emission $B_{max}$; finally, we studied an FDA-based multiple indicators discriminant model of coal and gas outburst, and applied the discriminant model to predict coal and gas outburst. The results showed that the discriminant model has 100% prediction accuracy, even when some conventional indexes are lower than the warning criteria. The FDA method has a broad application prospects in coal and gas outburst prediction.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.563-571
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• 2021

In this study, calcium alginate based cation exchange membrane was prepared and used to develop membrane capacitive deionization (MCDI) system for effective hardness control. As a major result, the MCDI with Ca-alginate membrane showed 27% better deionization capacity than the MCDI with a commercial cation exchange membrane. This superior improvement in the deionization capacity was expected to be due to the high ratio of transport number/electrical resistance (S_c/R_ratio) of Ca-alginate membrane. In addition, the MCDI with Ca-alginate membrane showed better deionization performance than the MCDI with Ca-alginate coating. This was because the space between the electrode and the Ca-alginate membrane was utilized for ion adsorption. The preliminary results indicated that the MCDI with Ca-alginate membrane can be a viable technique for the hardness control.

• 한국환경과학회지
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• 제18권11호
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• pp.1215-1224
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• 2009

This study evaluated the applicability of visible-light-driven N- and S-doped titanium dioxide($TiO_2$) for the control of low-level dimethyl sulfide(DMS) and dimethyl disulfide(DMDS). In addition, a photocatalytic unit(PU)-adsorption hybrid was evaluated in order to examine the removal of DMS and DMDS which exited the PU and a gaseous photocatalytic byproduct($SO_2$) which was generated during the photocatalytic processes. Fourier-Tranform-Infrared(FTIR) spectrum exhibited different surface characteristics among the three-types of catalysts. For the N- and S-doped $TiO_2$ powders, a shift of the absorbance spectrum towards the visible-light region was observed. The absorption edge for both the N- and S-doped $TiO_2$ was shifted to $\lambda$ 720 nm. The N-doped $TiO_2$ was superior to the S-doped $TiO_2$ in regards to DMS degradation. Under low input concentration(IC) conditions(0.039 and 0.027 ppm for DMS and DMDS, respectively), the N-doped $TiO_2$ revealed a high DMS removal efficiency(above 95%), but a gradual decreasing removal efficiency under high IC conditions(7.8 and 5.4 ppm for DMS and DMDS, respectively). Although the hybrid system exhibited a superior characteristic to PU alone regarding the removal efficiencies of both DMS and DMDS, this capability decreased during the course of a photocatalytic process under the high IC conditions. The present study identified the generation of sulfate ion on the catalyst surface and sulfur dioxide(maximum concentrations of 0.0019 and 0.0074 ppm for the photocatalytic processes of DMS and DMDS, respectively) in effluent gas of PU. However, this generation of $TiO_2$ would be an insignificant addition to indoor air quality levels.

• Journal of Pharmaceutical Investigation
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• 제31권4호
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• pp.225-232
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• 2001

The present study was carried out to observe the effect of liposome dispersed gel formulation (Lipogel) on topical delivery of ascorbyl palmitate (AsP). Neutral and negatively charged MLV liposomes containing AsP were prepared with dimyristoylphosphadtidylcholine (DMPC) and dicetyl phosphate (DCP), and dispersed to poloxamer gel matrix. In the hydrolysis study in rat's skin homogenates, AsP hydrolyzed to ascorbic acid (AsA) according to the first-order kinetics with the rate constant of $2.46{\times}10^{-2}\;min^{-1}$. In the passive skin penetration study using Franz diffusion cell, lipogel systems exhibited the greater values in the flux $(J_s)$ and the amount penetrated $(Q_p)$ compared to control hydrogels containing diethyleneglycol monoethyl ether $(Transcutol^{\circledR})$ as a solubilizing agent and a penetration enhancer for AsP. The total amount penetrated $(Q_{Total})$, which is expressed as a summation of $Q_P\;and\;Q_L$, for lipogel system was about 1.4 times higher in average than that of control hydrogel. However the amount localized in the skin $(Q_L)$ was similar in both formulations. As a result, lipogel system enhanced the skin penetration of AsP, possibly due to the increase in local concentration of AsP by preferential adsorption of liposome to the skin and the enhancing effect of phospholipid in liposome composition. Moreover it was expected that the penetrated AsP would generate AsA during skin penetration by the skin esterase. In conclusion, lipogel formulation was considered as a good candidate for topical delivery of AsP.