• 멤브레인
• /
• 제13권2호
• /
• pp.81-87
• /
• 2003

한외여과막의 분획분자량을 결정하기 위하여 dead-end형 셀내에 평막을 설치하고 분자량 분포가 수천 내지 수백만의 혼합 dextran 수용액으로 투과 실험하였다. 원료 용액과 투과액을 GPC로 분석하여 각 분자량에 대한 배제율을 구하고 90% 배제율에 해당하는 dextran분자량을 분획분자량를 결정하였다. 투과압력을 0.5에서 2.0 bar까지 증가시킬 경우, Millipore사의 PBTK막은 63,000 내지 68,000 daltons로 10% 이내에서 변화하였지만 Millipore사의 PBQK 막 또는 (주)새한의 UE1812막의 분획분자량은 각각 3.5 및 4.3 배 증가하였다. 또한 투과액을 원료용액의 10내지 40%까지 분리막을 증가시키면서 배제율을 측정한 결과, PBTK의 분획분자량은 25% 증가하였다.

• 한국물환경학회지
• /
• 제25권2호
• /
• pp.306-310
• /
• 2009

Packed-bed reactor for removing ammonia was tested at different loading rates. Nitrifiers for ammonia removing was encapsulated in gel media which consisted of polyethlene glycol, alginate and activated carbon. The removal efficiency was nearly 100% when ammonia loading was $12g/m^3/hr$, and the maximum elimination capacity (EC) achieved on this study was $18g/m^3/hr$. The initial microbial portion of nitrifiers in the media was about 82% and it was increased to more than 90% at the end of the operation. Short-term shock loading test was carried out to survey the stability of the media. The inlet loading rates were varied from 2 to $20g/m^3/hr$. The packed-bed reactor overcame the shock loading i.e. removal efficiency recovered rapidly from about 80% to almost 100% within 6 hrs. The results of Live/Dead cell test showed that nitrifiers maintained there activity in the encapsulated media during the test and also against ammonia shock load.

• Membrane and Water Treatment
• /
• 제11권2호
• /
• pp.131-139
• /
• 2020

The current study focused on the preparation of low-cost PVC-based adsorbing membrane. Metakaolin, as available adsorbent, was embedded into the PVC matrix via solution blending method. The as-prepared PVC/metakaolin mixed matrix membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), pure water permeability and contact angle measurements. The results confirmed the improvement of PWP and hydrophilicity due to the presence of metakaolin in the PVC matrix. Additionally the structure of PVC membrane was changed due to the incorporation of metakaolin in the polymer matrix. The static adsorption capacity of all samples was determined through dye removal. The effect of metakaolin dosage (0-7%) and pH (4, 8, 12) on dye adsorption capacity was investigated. The results depicted that the highest adsorption capacity was achieved at pH of 4 for all samples. Additionally, adsorption data were fitted on Langmuir, Freundlich, and Temkin models to determine the appropriate governing isotherm model. Finally, the dynamic adsorption capacity of the optimum PVC/metakaolin membrane was studied using dead-end filtration cell. The dye removal efficiency was determined for pure PVC and PVC/metakaolin membrane. The results demonstrated that PVC/metakaolin mixed matrix membrane had a high adsorption capacity for dye removal from aqueous solution.

• 멤브레인
• /
• 제16권4호
• /
• pp.303-312
• /
• 2006

상변환과 졸-겔 반응을 동시에 행하는 새로운 제막법으로 나노크기의 $ZrO_2$ 입자가 함유된 비대칭형 PES-$ZrO_2$ 복합 막을 제조하였다. PES-$ZrO_2$ 복합 막 제조의 최적 제막 조건을 복합 막에의 인 흡착실험을 수행하여 인 흡착량이 최대가 되는 조건으로서 결정하였는바, 최적 제막 조건은 캐스팅 용액에 1 mL의 PES 당 0.15 mL의 $Zr(PrO)_4$ 첨가 및 비용매 1 L에 1 mL $Zr(PrO)_4$ 당 30 mL의 $HNO_3$ 촉매를 첨가했을 때 이었다. 복합 막의 단면 구조, 막성능 및 $ZrO_2$ 입자 함유량 변화를 SEM, 순수투과량, TGA, ICP, XRD 및 접촉각 측정을 통해 결정하였는바, 캐스팅 용액에의 $Zr(PrO)_4$ 첨가량이 증가할수록 순수 투과량이 증가하며, $ZrO_2$ 입자 함유량은 1 mL의 PES 당 0.15 mL의 $Zr(PrO)_4$ 첨가했을 때 최대가 되었다. 복합 막의 표면 특성을 친수성으로 개선하기 위하여 인산처리를 하였으며, 인산처리 전후(前後)의 두 종류 PES-$ZrO_2$ 복합 막을 대상으로 한 BSA 용액의 dead-end 한외여과 실험을 수행하여 막오염 형성의 억제 정도를 평가한 결과 인산처리 시킨 복합 막의 경우 투과량과 BSA 배제도 모두 약 40% 정도 증가하였는데 이는 복합 막을 인산처리 시킴으로서 막특성이 친수화 되었기 때문이다.

• Toxicological Research
• /
• 제22권3호
• /
• pp.283-291
• /
• 2006

The survival and growth of epithelial cells depends on adhesion to the extracellular matrix. An adhesion signal may regulate the initiation of differentiation, since epidermal keratinocytes differentiate as they leave the basement membrane. A metabolically dead cornified cell envelope is the end point of epidermal differentiation so that this process may be viewed as a specialized form of programmed cell death. In order to investigate the precise cellular signaling events loading to terminal differentiation of keratinocytes, we have utilized HaCaT cells to monitor the biological consequences of $Ca^{2+}$ stimulation and numerous downstream signaling pathways, including activation of the extracellular signal-regulated protein kinase(ERK) pathway and activation of phosphatidylinositol 3-kinase(PI3K). The results presented in this study show that $Ca^{2+}$ function as potent agents for the differentiation of HaCaT keratinocytes, and this differentiation depends or the activation of ERK, Protein kinase B(PKB) and p70 ribosomal protein S6 kinase(p70S6K). Finally, the results show that the expression of Activator protein 1(AP-1; c-Jun and c-Fos) increased following $Ca^{2+}$-mediated differentiation of HaCaT cells, suggesting that ERK-mediated AP-1 expression is critical for initiating the terminal differentiation of keratinocytes.

• 한국산학기술학회논문지
• /
• 제21권12호
• /
• pp.488-493
• /
• 2020

친환경 에너지원으로 고려되는 수소의 수요가 증가하고 있고 이와 동시에 수소의 고효율 에너지변환이 가능한 설비인 연료전지의 시장 규모 또한 지속적으로 증가하고 있다. 본 연구는 수소를 에너지원으로 하는 주거건물의 운영비용을 감축하기 위한 연료전지 발전 부산물 활용기술에 대한 특허분석을 통해 관련 기술의 지식재산권 확보를 위한 전략을 수립하는데 목적을 두고 있다. 본 특허분석은, 2019 년 10 월까지 출원 공개 및 등록된 한국, 미국, 일본 및 유럽의 특허를 대상으로 분석하며 전문가회의를 거쳐 확정된 중분류 및 소분류 기술 체계를 기준으로 정량분석 및지표분석을 실시하였다. 특허분석을 통해, 2019년 10월까지 출원/공개/등록된 한국, 미국, 일본 및 유럽 특허를 조사하였고 전문가 토의를 바탕으로 기술분류체계 및 분류기준을 마련하였다. 특히, 수소에너지 주거건물의 운영비용 감축을 위해, 데드앤드 모드 운전을 통해 고분자전해질 연료전지 발전 시 생성되는 공기극 측 주요 부산물인 정화공기, 생성수분 및 산소희박 공기를 활용하는 시스템 및 방법으로 출원하여 권리화를 시도해 볼 수 있을 것으로 판단된다.

• Environmental Engineering Research
• /
• 제17권4호
• /
• pp.185-190
• /
• 2012

Rejection characteristics of perchlorate ($ClO_4^-$) were examined for commercially available reverse osmosis (RO) and nanofiltration (NF) membranes. A bench-scale dead-end stirred-cell filtration system was employed to determine the toxic ion rejection and the membrane flux. Model water solutions were used to prepare $ClO_4^-$ solutions (approximately, $1,000{\mu}g/L$) in the presence of background salts (NaCl, $Na_2SO_4$, and $CaCl_2$) at various pH values (3.5, 7, and 9.5) and solution ionic strengths (0.001, 0.01, and 0.01 M NaCl) in the presence of natural organic matter (NOM). Rejection by the membranes increased with increasing solution pH owing to increasingly negative membrane charge. In addition, the rejection of the target ion by the membranes increased with increasing solution ionic strength. The rejection of $ClO_4^-$ was consistently higher for the RO membrane than for the NF membrane and $ClO_4^-$ rejection followed the order $CaCl_2$ < NaCl < $Na_2SO_4$ at conditions of constant pH and ionic strength for both the RO and NF membranes. The possible influence of NOM on $ClO_4^-$ rejection by the membranes was also explored.

• 한국산업보건학회지
• /
• 제23권1호
• /
• pp.1-10
• /
• 2013

Objectives: The present study investigated the potential subacute toxicity of 1,4-dichlorobutane (1,4-DCB) by a 2-week repeated oral dose in male Sprague-Dawley rats. Materials and Methods: The test chemical was administered once daily by gavage to male rats at dose levels of 0, 74, 222, 667, and 2000 mg/kg/day for 2 weeks. All rats were sacrificed at the end of treatment period. During the test period, clinical signs, mortality, body weights, food and water consumption, urinalysis, hematology, serum biochemistry, gross findings, and organ weights were examined. Results: At 2000 mg/kg/day, treatment-related clinical signs, as evidenced by hypothermia, decreased locomotor activity, piloerection, lying on side, and prone position were observed. All the rats were found dead on test day 2. At 667 mg/kg/day, polyuria, suppressed body weight gain, food consumption, and spleen and thymus weights, and increased adrenal gland and liver weights were observed.Hematological and serum biochemical investigations revealed increases in the alanine aminotransferase, alkaline phosphataseand total bilirubinand decreases in the serum $Na^+$ level, white blood cell count and lymphocyte ratio. There were no treatment-related adverse effects in the 74 and 222 mg/kg/day groups. Conclusions: In the present experimental conditions, target organs were determined to be spleen, thymus,and liver. The no-observed-adverse-effect level was considered to be 222 mg/kg/day in male rats.

• Advances in materials Research
• /
• 제13권3호
• /
• pp.243-251
• /
• 2024

The asymmetric polylactic acid (PLA) membrane was prepared via phase inversion method using non-solvent induced separation (NIPS) technique. This study aims to synthesized as well as to characterize the PLA membrane and evaluating the membrane performance on water flux and permeability. In addition, this research also studied the removal performance of methylene blue dye. The polymer solution has been prepared using 12 wt.% of PLA and dissolved in 88 wt.% of Dimethylacetamide (DMAc) as a solvent. Then, the cast film was immersed in different ratio of coagulant bath medium (distilled water: methanol: ethanol) ranging from 100:0:0, 75:25:0, 75:0:25 and 75:12.5:12.5, respectively). Several characterizations were performed which include, membrane contact angle and membrane porosity. Performance PLA membranes were determined in terms of water flux and permeability at 1 bar transmembrane pressure using dead-end permeation cell. Finally, methylene blue (MB) removal efficiency was tested at the same transmembrane pressure. The findings revealed that the increase of alcohol concentration in coagulant bath resulted in higher porosity and lower contact angle. In short, MB dye rejection efficiency is also closely related to the amount of alcohol ratio used in coagulant baths. Increases in concentration of methanol and ethanol in coagulant bath medium increases the membrane porosity thus increased in efficiency of methylene blue rejection.

• 한국지반신소재학회논문집
• /
• 제13권4호
• /
• pp.77-85
• /
• 2014

헬리컬 파일(helical pile)은 회전 관입기로 시공이 가능하므로 비교적 소형의 장비로 말뚝 시공이 가능한 장점이 있어, 최근 다양한 현장에서 그 사용이 증가하고 있다. 그러나 헬리컬 파일의 지지력을 평가하기 위한 현장 정재하시험은 시험하중만큼의 사하중, 반력 말뚝, 반력 앵커 등이 필요하다는 단점이 있다. 본 연구에서는 헬리컬 파일에 상대적으로 재하장치가 간단하고 시험이 간편한 양방향 재하시험을 적용하였으며, 양방향 재하시험 결과와 정재하시험 결과를 비교하였다. 양방향 재하시험은 헬리컬 파일의 중공형 중심축(shaft)에 중심축의 직경과 일치하고 중심축 내부 공간으로 유압재하용 호스가 나올 수 있도록 특수하게 제작된 유압식 셀(cell)을 나선형 원판(helix plate)사이에 삽입한 후, 유압 셀(cell)에 가압하여 지지력을 측정하는 방식으로 수행되었다. 양방향 재하시험은 유압식 셀을 최하단 나선형 원판 상부에 삽입한 경우와 최상단 나선형 원판 상부에 삽입한 두 가지 케이스로 시험을 진행하였으며, 각각의 방법이 선단지지력과 주면마찰력을 측정할 수 있도록 말뚝 두부의 변형을 제한하였다. 시험은 89mm, 114mm의 중심축에 450mm, 350mm, 200mm의 나선형 원판을 부착하여 제작한 헬리컬 파일로 수행되었으며, 시험 결과 정재하시험으로 산정한 지지력과 양방향 재하시험으로 산정한 지지력이 유사함을 확인하였다.