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        검색결과 8

        1.
        2018.11 구독 인증기관·개인회원 무료
        본 실험에서는 조류 제거 및 농축을 위해 Silicon Carbide(SiC) 재질의 침지형 세라믹막을 적용하여 운전 특성을 평가하고자 하였다. SiC 세라믹막은 막표면이 음전하를 띄어 음전하를 띄는 조류 제거에 적용이 가능하고 고유량으로 역세척(Backwashing)을 할 수 있어 고농도의 조류 농축시에도 적용이 가능하다. 역세척 유량과 역세척 시간, 역세척수 수온, 역세척수에 차아염소산나트륨 주입 유무, 여과/역세시 air scrubbing 유량에 따라 역세척 효율을 평가하였으며 Jar test를 통해 선정한 농도로 응집제 주입 유무에 따라 운전 특성을 비교하였다. 또한 동일한 조건에서 세라믹막과 유기막의 운전 특성과 비교하였다. 본 연구는 환경부의 “환경정책기반공공기술개발사업”으로 지원받은 과제입니다.
        2.
        2018.11 구독 인증기관·개인회원 무료
        본 실험에서는 대청호에서 발생한 남조류를 대상으로 SiC(Silicon carbide) 평막의 최적 운전조건을 도출하고자 하였다. 이를 위해 원수 농도에 따른 투과플럭스, 응집제 주입 조건, Air scrubbing 조건, 역세척(Backwashing) 유량 및 시간, 여과 및 역세척 시간, 응집제 종류 및 주입 농도 등에 대해 안정적으로 운전이 가능한 최적 조건을 도출하였다. 특히, 저농도의 응집제 주입에도 음전하를 띄는 조류 입자들과 전기적으로 중화를 일으켜서 생성된 미세 플럭들이 SiC 평막의 막표면에서 투수성을 증가시킨 것으로 사료된다. 이를 통해 도출된 설계인자로 제작한 Pilot Plant를 조류 제거시 적용하고자 한다. 본 연구는 환경부의 “환경정책기반공공기술개발사업”으로 지원받은 과제입니다.
        3.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study applied microbubbles to reduce membrane fouling in wastewater reuse membrane processes, evaluated and compared the transmembrane pressure with or without the application of microbubbles and the cleaning efficiency with the application of aeration and microbubbles. In addition, this study analyzed foulants removed from the membrane surface. Changes in the transmembrane pressure of membranes with the presence or absence of microbubbles were observed. As a result, transmembrane pressure (TMP) increasing rate decreased twofold when applying microbubbles to realize stable operations. This study compared and evaluated cleaning efficiency applying aeration and microbubbles. As a result, the cleaning efficiency was 5% higher on average when applying microbubbles. In turbidity and total organic carbon (TOC), foulants were discharged when applying microbubbles twice as much as applying aeration. It is thought that particulate foulants precipitated on the membrane surface were more likely to desorb because the adhesion between the membrane surface and particle was weakened by microbubbles. Therefore, it is considered possible to effectively control membrane fouling because of the increase in cleaning efficiency when applying microbubbles to wastewater reuse membrane processes.
        4,000원
        4.
        2017.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Microfiltration (MF) and Ultrafiltration (UF) membrane processes capable of producing highly purified water have been extensively applied as a pretreatment process in the wastewater reuse field with the improvement of membrane properties and resistance, development of operating protocols, and improvement of technologies of backwashing and physicochemical cleaning, and improvement of scale and antifoulants. However, despite of the development of membrane production and process technologies, fouling still remains unresolved. This study confirmed that foulants such as polysaccharides, proteins and humic substances existed in final treated effluent (secondary effluent) by fluorescence excitation emission matrix (FEEM) and fourier transform infrared spectroscopy (FTIR) analysis. In addition, when constructing ozone oxidation and coagulation processes as a hybrid process, the removal efficiency was 5.8%, 6.9%, 5.9%, and 28.2% higher than that of the single process using coagulation in turbidity, color, dissolved organic carbon (DOC), and UV254, respectively. The reversible and irreversible resistances in applying the hybrid process consisting of ozone oxidation and coagulation processes were lower than those in applying ozone oxidation and coagulation processes separately in UF membrane process. Therefore, it is considered possible to apply ozonation/coagulation as a pretreatment process for stable wastewater reuse by and then contributing to the reduction of fouling when calculating the optimal conditions for ozone oxidation and coagulation and then to applying them to membrane processes.
        4,000원
        5.
        2010.09 구독 인증기관 무료, 개인회원 유료
        Embryoid bodies (EBs) generated from human embryonic stem cells (hESCs) include spontaneously induced endodermal lineage cells (ELCs). Activin-A plays important roles in the endoderm differentiation of hESCs. Despite studies on the generation of ELCs from hESCs with treatment of Actvin-A, it was unclear for localization and pattern of ELCs by Activin-A during differentiation of hESCs. Accordingly in this study, we knew that Actvin-A increased the cystic EBs formation, including the highly enriched AFP (endoderm lineage specific marker)-expressing cells in the surface of cystic EBs. To induce the EBs formation from undifferentiated hESCs, cells were transferred onto petri-dish and cultured in suspension condition without bFGF removed hESC media (EB media) for 3 days. Next to investigate the effect of Activin-A, EBs were subsequently cultured in EB media supplement with 100 ng/ml Activin-A for 3 days. After 5~7 days of Activin-A treatment, cystic EBs began to appear which increased in numbers reaching ~60% of initially formed EBs over 5 days. Endoderm lineage marker, AFP were highly expressed and specifically localized at the surface region of cystic EBs comparison with normal EBs. We next attached the cystic EBs onto gelatin-coated plates and cultured for 5 days. In the results of real-time PCR and immunocytochemistry analysis, AFP-expressing cells migrated and localized at the outgrowth region of attached cystic EBs. To obtain the AFP-expressing cells of the outgrowth region, we manually isolated by using micro- dissection and cultured them. These cells strongly express AFP over 70% of isolated cells post re-plating. Here, we first showed an expression pattern of specifically localized ELCs by Activin-A during differentiation of hESCs. From this observation, we could highly purified ELCs from undifferentiated hESCs. Taken together, our system will provide a novel and efficient option to generate ELCs from hESCs.
        4,000원
        6.
        2010.03 구독 인증기관 무료, 개인회원 유료
        Mesenchymal stem cells (MSCs) have the multipotent capacity and this potential can be applied for obtaining valuable cell types which can use for cell therapy on various regenerative diseases. However, insufficient availability of cellular source is the major problem in cell therapy field using adult stem cell sources. Recently, human embryonic stem cells (hESCs) have been highlighted to overcome a limitation of adult cellular sources because they retain unlimited proliferation capacity and pluripotency. To use of hESCs in cell therapy, above all, animal pathogen free culture system and purification of a specific target cell population to avoid teratoma formation are required. In this study, we describe the differentiation of a mesenchymal stem cell-like cells population from feeder-free cultured hESCs(hESC-MSCs) using direct induction system. hESC-MSCs revealed characteristics similar to MSCs derived from bone marrow, and undifferentiated cell markers were extremely low in hESC-MSCs in RT- PCR, immunostaining and FACS analyses. Thus, this study proffer a basis of effective generation of specialized human mesenchymal stem cell types which can use for further clinical applications, from xenofree cultured hESCs using direct induction system.
        4,000원
        7.
        2008.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The magneto-transport properties of an individual single crystalline Bi nanowire grown by aspontaneous growth method are reported. A four-terminal device based on an individual 400-nm-diameternanowire was successfully fabricated using a plasma etching technique that removed an oxide layer that hadformed on the surface of the nanowire. Large transverse ordinary magnetoresistance (1401%) and negativelongitudinal ordinary magnetoresistance (−38%) were measured at 2K. It was observed that the period ofShubnikov-de Haas oscillations in transverse geometry was 0.074T−1, 0.16T−1 and 0.77T−1, which is in goodagreement with those of bulk Bi. However, it was found that the period of SdH oscillation in longitudinalgeometry is 0.24T−1, which is larger than the value of 0.16T−1 reported for bulk Bi. The deviation is attributableto the spatial confinement arising from scattering at the nanowire surface boundary.
        3,000원
        8.
        2020.12 KCI 등재 서비스 종료(열람 제한)
        Non-point source pollutants have characteristics the render them difficult to manage owing to the uncertainty of flow paths. As agricultural non-point sources account for more than 57% of non-point source pollutants, the necessity for management is increasing. This study examines the possibility of utilizing land cover maps to suggest a more appropriate method of setting management priority for agricultural non-point sources in the Daecheong Lake area and draws implications by comparing the results derived using the cadastral map, as mentioned in the TMDL Basic Policy. To define the prioritized areas for management, the pollution load was calculated for each subbasin using the formula from the TMDL technical guidelines. As a result, the difference in the average pollution load between the land cover map and cadastral map ranged from 11.6% to 21% among the subbasins. In almost all subbasins, there were differences in the ranking of management priorities depending on the land information that was used. In addition, it was found that it was reasonable to use the level 3 land cover map to calculate the load generated by the land system for examining the implementation goals and methods of each data and comparing them with satellite images.