• 한국재료학회지
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• 제13권9호
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• pp.593-597
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• 2003

Anodic aluminum oxide (AAO) membrane was made of aluminum sheet (99.6%, 0.2 mm thickness). The regular array of hexagonal nano pores or channels were prepared by two step anodization process. A detail description of the AAO fabrication is presented. After the 1st anodization in oxalic acid (0.3 M) at 45 V, The formed AAO was removed by etching in a solution of 6 wt% $H_3$$PO_4$＋1.8 wt% $H_2$$CrO_4$. The regular arrangement of the pores was obtained by the 2nd anodization, which was carried out in the same condition as the 1st anodization. Subsequently, the alumina barrier layer at the bottom of the channel layer was removed in phosphoric acid (1M) after removing of aluminum. Pore diameter, density, and thickness could be controlled by the anodization process parameters such as applied voltage, anodizing time, pore widening time, etc. The pore diameter is proportional to the applied voltage and pore widening time. The pore density and thickness can be controlled by anodization temperature and voltage.

• 멤브레인
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• 제6권4호
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• pp.250-257
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• 1996

글루탈알데히드와 황산을 이용하여 가교된 키토산 복합막을 제조하였다. 제조된 복합막은 글루탈알데히드와 황산용액을 이용하여 표면말을 선택적으로 가교하엿다. 제조된 키토산 막에서의 키토산과 아세트산간의 착체형성의 영향을 관찰하기 위하여 수산화나트륨으로 중화하여 성능을 비교하였다. 황산으로 표면을 가교한 경우 코팅된 활성층의 투과증발에 대한 영향을 관찰하였다. 글루탈알데히드로 가교된 키토산복합막은 지지체의 종류를 변화시키면서 투과증발성능을 비교하였다. 지지체의 순수투과성능이 증가할수록 투과유량은 비슷한 값들을 유지하였으며, 선택도는 증가하다가 다시 감소하는 경향을 나타내었다. 수산화나트륨으로 키토산을 중화시킨 경우에는 선택도는 감소하였고 투과유량은 유지되는 경향을 나타내었다. 황산을 이용하여 표면을 이온가교시킨 경우 키토산 복합막은 활성충우ㅏ 두께가 증가할수록 가교시간이 증가하여야 최적의 가교조건을 나타내었다.

• 멤브레인
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• 제17권1호
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• pp.14-22
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• 2007

본 연구는 투과증발법을 이용하여 수용액 중 미량의 목련 향 성분을 농축하는 방법으로, PVDF/PDMS 복합막을 제조하여 지지막의 구조와 활성층의 두께에 따른 분리능의 변화를 살펴보았다. PVDF 지지막은 제막조건인 응고액의 온도가 감소하고 고분자 농도가 증가함에 따라 지지층에서의 표면공극률과 기공의 직경이 감소함을 순수투과실험을 통해서 간접적으로 확인하였고, 복합막에 대한 지지막 구조의 영향을 투과 mechanism식에 적용하여 해석하였다. 또한 PDMS의 두께가 증가됨에 따라 선택도가 증가하는 결과를 통해서, 활성층에서의 물질전달을 Fick's law에 의하여 설명하는데 제한이 있음을 알 수 있었다.

• Journal of Periodontal and Implant Science
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• 제41권1호
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• pp.23-29
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• 2011

Purpose: To investigate the healing pattern of the mucous membrane after tooth extraction necessitated by periodontal disease in the maxillary sinus. Methods: One hundred and three patients with 119 maxillary sinuses were investigated. Before implant placement, cone-beam computed tomography (CT) scanning was performed. The causes of extraction, the time elapsed since extraction, smoking, periodontal disease in adjacent teeth, and gender were recorded. In addition, the thickness of the mucous membrane of the maxillary sinus and the height of residual alveolar bone at the extracted area were calculated from CT images. Results: The thickness of the mucous membrane in the periodontal disease group ($3.05{\pm}2.71\;mm$) was greater than that of the pulp disease group ($1.92{\pm}1.78\;mm$) and the tooth fracture group ($1.35{\pm}0.55\;mm$; P<0.05). The causes of extraction, the time elapsed since extraction, and gender had relationships with a thickening of the mucous membrane of the maxillary sinus (P<0.05). In contrast, the height of the residual alveolar bone at the extracted area, periodontal disease in adjacent teeth, and smoking did not show any relation to the thickening of the mucous membrane of the maxillary sinus. Conclusions: The present study revealed distinct differences in healing patterns according to the causes of extraction in the maxillary sinus, especially periodontal disease, which resulted in more severe thickening of the mucous membrane.

• 멤브레인
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• 제32권5호
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• pp.336-347
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• 2022

역전기투석(reverse electrodialysis, RED)은 이온교환막을 격막으로 이용하여 해수와 담수의 농도차로부터 발전하는 유망한 친환경 재생에너지 기술 중 하나이다. 이온교환막은 RED의 성능을 좌우하는 핵심 구성요소로 낮은 전기적 저항, 높은 이온선택투과도, 우수한 내구성 및 저렴한 제조 비용 등의 요구조건을 만족시켜야 한다. 본 연구에서는 다양한 두께 및 기공율을 갖는 다공성 고분자 지지체를 이용하여 세공충진 음이온교환막을 제조하고 이온교환 고분자의 조성과 막 두께가 RED의 발전 성능에 미치는 영향을 조사하였다. 이온교환막의 전기적 저항이 충분히 낮은 경우 RED 발전 성능은 주로 막의 apparent permselectivity에 의해 좌우됨을 확인할 수 있었다. 또한 막의 apparent permselectivity는 IEC, 가교도, 막 두께, 표면 개질 등을 통해 향상시킬 수 있으며 전기적 저항과의 trade off 관계를 고려하여 최적 조건을 찾아야 함을 확인하였다.

• 항공우주기술
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• 제2권2호
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• pp.133-141
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• 2003

초소성 공정을 이용하여 구형 압력용기를 제작하는 경우 두께와 구형의 형상은 일정하지 않고 성형공정이 진행함에 따라 변하게 된다. 본 연구에서는 공정과정 동안 발생하는 초기 블랭크의 두께변화 예측을 이론적으로 해석하였다. 두께변화 예측을 위한 이론적인 모델은 Kuglov 등이 적용한 박막이론을 사용하였으며 요구되는 최종 두께를 얻기 위한 초기 블랭크의 두께, 블랭크의 균일한 변형을 얻기 위한 시간에 따른 압력 프로파일, 각 성형단계에서 위치에 따른 두께분포 및 시간에 따른 두께분포를 결정하였다. 공정 단계 전반에 걸쳐서 적용 모델 및 해석 프로그램의 적합성을 문헌의 시험 결과와 비교하여 검증하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권5호
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• pp.289-294
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• 2002

Cellulose production by Acetobacter pasteurianus was investigated in static culture using four bioreactors with silicone rubber membrane submerged in the medium. The shape of the membrane was flat sheet, flat sack, tube and cylindrical balloon. Production rate of cellulose as well as its yield on consumed glucose by the bacteria grown on the flat type membranes was approximately ten-fold greater than those on the non-flat ones in spite of the same membrane thickness. The membrane reactor using flat sacks of silicone rubber membrane as support of bacterial pellicle can supply greater ratio of surface to volume than a conventional liquid surface culture and is promising for industrial production of bacterial cellulose in large scale.

• Korean Membrane Journal
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• 제5권1호
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• pp.61-67
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• 2003

Various characteristics of ion transport properties of a charged mosaic membrane with a parallel array of positive and negative functional charges were investigated, From the analysis of the volume flux, it was found that the salt flux based on nonequilibrium thermodynamics, preferential salt transport across the charged mosaic membrane. Transport properties of the magnesium sulfate(MgSO$_4$) and sucrose across the charged mosaic membrane were estimated. As a result, metal salts transport depended largely on the charged states and molecular weight otherwise nonelectrolyte solution was rejected under all experimental conditions. On the other hand, the reflection coefficient s indicated the negative value that suggested preferential material transport and was independent of charged mosaic thickness.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.312-313
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• 2006

The primary aim pursued by the preparation of separation membrane is the preparation of the membrane thin as well as with no defect. The field-flow fractionation deposition is a new molding technology which can overcome the traditional disadvantages such as multi-preparation to the preparation of great area of separation membrane with no defect. Therefor the mainly ingredients which influence the appearance and performance of titanium membrane layer are investigated by scanning electricity mirror (SEM) as well as porous material testing instrument: powder performance prepared and confected; selection of supporting body; sintering system such as temperature and time. It is shown that the membrane thickness can be controlled at $50{\mu}m$ or so; the filtration precision mainly rests with powder performance and selection of supporting body and little sintering system

• 한국막학회:학술대회논문집
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• 한국막학회 2002년도 제15회 심포지움
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• pp.23-46
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• 2002

The cryogenic, pressure swing adsorption and membrane methods have been used to separate air into nitrogen and oxygen. The air separation membrane is made of the polymers, of which manufacturing process is complicate and it causes a little high production cost. Polymer membrane has temperature limit in usage and low durability even at moderate temperature. Therefore, inorganic membranes have been studied for years. As formation of unit alumino-silicate membrane, unit cells of membrane were made with a few coating methods. In this study the dipping of substrate into sols, application of vacuum to the opposite side of substrate with coating and rotating of the substrate in the sols were found as good coating memthods to make a uniform coating and to control the thickness of membrane. The membrane coats were examined by SEM and XRD. The sample ESZl-1 was compared with those of samples that prepared by another method. The present developed coating methods could be applied to the various types of zeolite membrane formation, that is A- X-, Y- ZSM- and MCM-types of membranes. Also these membrane forming methods could be applied to formation of catalyst absorbed zeolite membrane, of which zeolite absorb the catalytic metals. The product obtained from these coating methods could be applied to the industrial gas and liquid phase catalytic reaction and separation processes.