• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.98-107
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• 2017

Pd-based membranes have been widely used in hydrogen purification and separation due to their high hydrogen diffusivity and infinite selectivity. However, it has been difficult to fabricate thin and dense Pd-based membranes on a porous stainless steel(PSS) support. In case of a conventional PSS support having the large size of surface pores, it was required to use complex surface treatment and thick Pd coating more than $6{\mu}m$ on the PSS was required in order to form pore free surface. In this study, we could fabricate thin and dense Pd membrane with only $3{\mu}m$ Pd layer on a new PSS support manufactured by metal injection molding(MIM). The PSS support had low surface roughness and mean pore size of $5{\mu}m$. Pd membrane were prepared by advanced Pd sputter deposition on the modified PSS support using fine polishing and YSZ vacuum filling surface treatment. At temperature $400^{\circ}C$ and transmembrane pressure difference of 1 bar, hydrogen flux and selectivity of $H_2/N_2$ were $11.22ml\;cm^{-2}min^{-1}$ and infinity, respectively. Comparing with $6{\mu}m$ Pd membrane, $3{\mu}m$ Pd membrane showed 2.5 times higher hydrogen flux which could be due to the decreased Pd layer thickness from $6{\mu}m$ to $3{\mu}m$ and an increased porosity. It was also found that pressure exponent was changed from 0.5 on $6{\mu}m$ Pd membrane to 0.8 on $3{\mu}m$ Pd membrane.

• The Korean Journal of Physiology
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• v.1 no.2
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• pp.151-156
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• 1967

Outward movement of hemoglobin and $K^+$ ion across rabbit erythrocyte membrane after heating, cooling and in acid medium was studied. One milliliter of rabbit blood was centrifuged and packed red cells were obtained. Packed red cells were resuspended by addition of 4 ml of 0.9% NaCl solution and were subjected to heating $(57^{\circ}C\;for\;5\;minutes)$ or cooling $(-4^{\circ}C{\sim}-8^{\circ}C\;of\;-10^{\circ}C{\sim}-11^{\circ}C\;for\;10\;minutes) $. For acid medium experiment packed ref cells were resuspended by addition of 4 ml of acid medium of PH 4.5 consisting of 0.01% glacial acetic acid in 0.85% NaCl solution and kept standing for 10 minutes. All red cell suspensions were centrifuged again and packed red cells were separated. This packed red cells were again suspended in 4 ml of NaCl solution of 0.8%, 0.7%, 0.6%, and 0.5% concentration respectively and kept standing for 20 minutes. The concentration of hemoglobin and $K^+$ in the supernatant of the above red cell suspensions were measured and the following results were obtained. 1. Outward movement of hemoglobin and $K^+$ was greatest in red cells subjected to heating. The movement paralled to the osmolal concentration gradient between extra- and intra-cellular phase of red cells. 2. In acid medium the outflux of hemoglobin and $K^+$ increased as compared to the control. 3. In red cells subjected to the cold of $-10^{\circ}C{\sim}-11^{\circ}C$ the outflux of hemoglobin and $K^+$ increased. Whereas in the environment of $-4^{\circ}C{\sim}-8^{\circ}C$ there was no change in the outflux of $K^+$. The he-moglobin outflux showed rather a decreased as compared to tile control.

• Journal of Pharmaceutical Investigation
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• v.28 no.1
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• pp.25-33
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• 1998

Intestinal absorption of ${\beta}-lactam$ antibiotics and angiotensin converting enzyme(ACE) inhibitors has been shown to use the carrier-mediated transport system. In vitro experiments have established that the efficacy of uptake by enterocytes depends on an inwardly directed proton gradient. It was suggested that benazepril was mediated by tripeptide transport system and that amoxicillin was transported by dipeptide transport carrier. The aim of this study is to assess the influence of amoxicillin on the intestinal absorption of benazepril using in vitro diffusion chamber and in situ single pass perfusion technique in the rat in order to elucidate whether the above transport systems are competitive or not. We obtained the gastrointestinal pemeability coefficient of amoxicillin, benazepril and both of them using in vitro diffusion chamber. And also the gastrointestinal absorption clearance of amoxicillin, benazepril and both of them using in situ single-pass perfusion method at steady state were calculated. Amoxicillin and benazepril were analyzed by HPLC. The results by the use of diffusion chamber in vitro indicated that the apparent intestinal permeability coefficient of benazepril was significantly(p<0.01) decreased by amoxicillin(45.2%) and vice versa significantly(p<0.01) decreased(89.1%). The results by the in situ gastrointestinal single-pass perfusion method indicated that the intestinal absorption clearance of benazepril was significantly(p<0.05) decreased by amoxicillin (40.2%) and vice versa significantly(p<0.05) decreased(54.8%). These results might suggest that they share the same peptide carrier pathway for oral absorption.

• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.21-26
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• 2002

The primary culture of human nasal epithelial cell monolayer was performed on a Transwell. The effect of various factors on the tight junction formation was observed in order to develop an in vitro experimental system for nasal transport studies. Human nasal epithelial cells, collected from human normal inferior turbinates, were plated onto diverse inserts. After 4 days, media of the apical surface was removed for air-liquid interface (ALI) culture. Morphological characteristics was observed by transmission electron microscopy (TEM). A polyester membrane of $0.4\;{\mu}m$ pore size was determined as the most effective insert based on the change in the transepithelial electric resistance (TEER) value as well as the $^{14}C-mannitol$ transport study. The ALI method was effective in developing the tight junction as observed in the further increase in the TEER value and reduction in the permeability coefficient $(P_{app})$ of $^{14}C-mannitol$ transport. Results of the transport study of a model drug, budesonide, showed that the primary culture system developed in this study could be further developed and applied for in vitro nasal transport studies.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.335-335
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• 2007

본 연구에서는 RF Magnetron Sputtering 법으로 94:6 wt%의 비율로 Sb가 첨가된 $SnO_2$ 타겟을 사용하여 실온에서 ATO(Antimony doped Tin Oxide) 박막을 증착하고, 열처리가 ATO 박막의 구조적, 전기적, 광학적 특성에 미치는 효과를 연구하고자 하였다. ATO 박막의 두께는 약 200 nm로 증착하였으며, 실험 조건으로는 Ar 유량을 100 seem, 진공도는 1, 5, 10 mTorr로 변화시켰으며 스퍼터링 파워는 100, 150, 200, 250 W로 조절하였다. 증착되어진 박막은 vacuum 상태에서 300, $600^{\circ}C$의 온도에서 열처리를 수행하였으며 결과적으로 스퍼터링 파워가 증가함에 따라 비저항이 감소하였고, 250 W의 파워와 10 mTorr의 공정압력 조건에서 $600^{\circ}C$로 열처리한 ATO 박막은 $5{\times}10^{-3}{\Omega}-cm$의 저항률과 85.3%의 높은 투과도를 가지는 우수한 투명 전도막을 얻을 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.77-77
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• 2010

그래핀(Graphene)은 한 겹(layer)의 2차원 판상 구조에 탄소원자들이 육각형의 기본 형태로 배열되어 있는 나노재료로서, 우수한 역학적 강도와 화학적, 열적 안정성 및 흥미로운 전기 전자적 성질을 가지고 있는 것으로 알려져 있다. 최근, 이러한 특징적이고도 우수한 물성으로 인하여 기초물성 연구에서부터 차세대 응용까지 고려한 각종 연구들이 활발하게 진행되고 있다. 일반적으로 그래핀을 얻는 방법에는 물리 화학적 박리, 열화학증기증착법(TCVD), 탄화규소의 흑연화, 흑연산화물의 환원 등의 방법들이 알려져 있다. 그 중 TCVD법이 두께의 균일성이 높은 그래핀을 합성하는데 가장 적절한 것으로 알려져 있다. 그러나 TCVD법은 탄소를 포함하는 원료가스를 분해하기 위하여 고온의 공정을 필요로 하게 되지만, 향후 산업적 응용을 고려한다면 대면적 그래핀의 저온합성법 개발은 풀어야 할 시급한 과제로 인식되고 있다. 현재는 메탄을 원료가스로 사용하여 $900^{\circ}C$ 이상에서 그래핀을 합성하는 추세이고, 최근 아세틸렌등의 활성원료가스를 이용하여 $900^{\circ}C$ 이하에서 저온 합성한 연구결과들도 속속 보고되고 있다. 본 연구에서는 고주파 플라즈마를 이용하여 비교적 저온에서 탄소원료가스를 효율적으로 분해하고, 확산플라즈마 영역에 TCVD 챔버를 결합한 하이브리드 화학증기증착법을 이용하여 그래핀의 저온합성을 도모하였다. 원료가스로는 메탄을 사용하였고, 기판으로는 전자빔증착법으로 증착한 니켈 박막 및 구리포일을 사용하였다. 실험결과, 그래핀은 $600^{\circ}C$ 부근의 저온에서도 수 층으로 이루어진 그래핀이 합성된 것을 확인하였다. 합성한 그래핀은 분석의 용이함 및 향후 다양한 응용을 위하여 실리콘산화막 및 투명고분자 기판 위에 전사(transfer)하였다. 합성된 그래핀의 구조평가를 위해서는 광학현미경과 Raman분광기를 주로 사용하였으며, 원자힘현미경(AFM), 주사전자현미경(SEM), 투과전자현미경(TEM) 등도 이용하였다.

• Journal of Korean Medicine for Obesity Research
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• v.13 no.1
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• pp.24-32
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• 2013

Objectives: The aim of this study is to investigate anti-imflammatory and protective effect for intestinal epithelial cells with Atractylodes macrocephae (AM), a traditional Korean Herbal medicine and fermented Atractylodes macrocephae (FAM) with Lactobacillus plantarum. Methods: HCT-116 and Raw 264.7 cells were used in this study. Using NO assay, we measured lipopolysaccharide (LPS)-induced anti-inflammatory effect. We measured permeability of intestinal epithelial cells with transepithelial electrical resistance and horseradish peroxide flux assay. Water soluble tetrazolium salt assay was used to see cell proliferation. All the results were presented in mean and standard deviation. We used Student's t-test for analyzing significance of results. Results: In Raw 264.7 cells NO production decreased 22.4% with pre-treatment of AM and FAM, especially with FAM in high concentration. In HCT-116 cells LPS-induced intestinal permeability had a protective effect with both AM and FAM, which was also tend to be proportional to the concentration. Cell viability increased up to 135.52% after treatment of high concentration of FAM in HCT-116, while there was no significant change in Raw 264.7 cells with herb treatments. Conclusions: These results show evidence that AM, especially fermented ones, significantly reduced intestinal membrane permeability. They also had a protective effect as well as an anti-inflammation effect for HCT-116 and Raw 264.7 cells. This suggest that FAM may be a therapeutic agent for Leaky gut syndrome by reducing intestinal permeability.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.62-71
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• 2019

Al1050 and Al7075 alloy specimens were exposed to atmospheric conditions for 24 months and analyzed by Transmission Electron Microscopy to characterize their corrosion behavior and oxide film characteristics, especially focusing on intergranular corrosion or oxidation. In general, the intergranular oxygen penetration depth of Al1050 was deeper than Al7075. Since O and Si signals were overlapped at the oxidized grain boundaries of Al1050 and Mg is not included in Al1050, it is concluded that Si segregated along the grain boundaries directly impacts on the intergranular corrosion of Al1050. Cr-Si or Mg-Si intermetallic particles were not observed along the grain boundaries of Al7050, but Mg-Si particle was barely observed in the matrix. 10-nm size Mg-Zn particles were also found all over the matrix. Mg was mainly observed along the oxidized grain boundary of Al7075, but Si was not detected due to the Mg-Si particle formation in the matrix and relatively low concentration of Si in Al7075. Therefore, it is thought that Mg plays an important role in the intergranular corrosion of Al7075 under atmospheric corrosion conditions.

• Membrane Journal
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• v.31 no.5
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• pp.333-342
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• 2021

A flexible electrochromic device (ECD) is a promising technology that is expected to be applied in various fields such as smart windows. Polymer electrolyte is an important component that determines the bleaching-coloration performance and physical stability of flexible ECDs. In this study, a pore-filled polymer electrolyte membrane (PFPEM) with excellent dimensional stability was developed to effectively fabricate flexible ECDs and improve durability. Polyvinyl acetate, which has excellent adhesion, and polyethylene glycol, which can improve ionic conductivity, were filled in the pores of a porous substrate made of polyethylene, which is inexpensive and has excellent physical and chemical stability. The optimal lithium salt (LiTFSI) content of the prepared PFPEM was determined at about 27 wt%, and it was confirmed to possess excellent dimensional stability, adhesive strength, and ion conductivity close to that of conventional polymer electrolytes. Although the visible light transmittance was lowered by the use of the porous substrate, it was expected to act as an advantage in the colored state.