• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.553-560
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• 1999

The aim of the present study was to evaluate the effect of the expanded polytetrafluoroethylene (e-PTFE) membrane exposure on the initial healing of the periodontal tissue in guided tissue regeneration (GTR) procedure. 90 sites selected from 90 patients were treated with gingival flap surgery supported by an e-PTFE membrane. The material included angular bony defects with probing attachment loss of > 5mm or degree II furcation involvement. Treated sites were classified with membrane exposure group and non-exposure group at membrane removal and evaluated healing type. The results were obtained as follows. 1. e-PTFE membrane was exposed at 61 sites (67.8%) among 90 sites. 2. Thirteen sites (14.4%) depicted rapid healing type, 65 sites (72.2%) depicted typical healing type, 9 sites (10%) showed delayed healing type and 3 sites (3.3%) were categorized as adversed healing type. 3. In e-PTFE membrane exposure group, 1 site (1.6%), 51 sites (83.6%), 6 sites (9.8%) and 3 sites (4.9%) showed rapid healing type, typical healing type, delayed healing type and adverse healing type respectively. 4. In e-PTFE membrane non-exposure group, 12 sites (41.3%), 14 sites (48.3%) and 3 sites (10.3%) showed rapid healing type, typical healing type and delayed healing type respectively. Adverse healing type was not observed. 5. The rate of favourable healing between e-PTFE membrane exposure group and non-exposure group was not statistically significant(p=0.56). These results suggest that the prevention of membrane exposure may be important to obtain rapid healing type. However favourable healing could be obtained with stringent infection control program even if membrane was exposed.

• 상하수도학회지
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• 제16권6호
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.427-432
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• 1998

중수속의 삼중수소 제거 공정인 액상 촉매 교환 반응에서 중수의 촉매 표면 응축에 의한 성능 저하가 큰 문제의 하나로서 성능 저하를 감소시키기 위한 여러 가지 형태의 촉매탑이 고안 되었다. 본 연구에서는 membrane을 사용하여 중수와 촉매를 분리시킴으로써 촉매 성능 저하를 감소시킬 수 있는 촉매탑의 설계를 시도하였다. 세 가지 촉매탑이 고안되었는데 sheet type의 membrane을 사용한 multilayered type 과 double spiral type, hollow fiber membrane을 사용한 hollow fiber cartridge type 등이다. multilayered type은 구조가 단순하여 scale-up이 용이하고 double spiral type은 다른 type보다 유로의 blocking 문제가 작고 hollow fiber cartridge type은 최대의 비표면적을 가질 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제21권1호
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• pp.49-58
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• 1997

The membrane type LNG tank is non self-supporting tank which consists of both primary and secondary membrane supported through the insulation boxes by the adjacent hull struc¬ture. Although the membranes are not structural member. They are subject to periodical cyclic loads due to the thermal expansion and other expansions or contraction of membrane. At the design stage of the tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds is necessary in order to assist the designer and the inpector. In this study the evaluation method of fatigue strength of membrane type LNG tank is pre¬sented with FEM analysis and fatigue test of lap welds and it contains the following:1) The fatigue tests and preparation of design S - N curve for lap welds 2) FEM analysis of test specimens 3) Estimation of cumulative damage factor of lap welds 4) Guideline for inspection of lap welds of membrane type LNG tank As the results of analytical and experimental approaches in this study, the evaluation method of fatigue strengths of membrane type LNG tank is proposed, which is expected to be useful for design and inspection of membrane type LNG tank.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1036-1039
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• 2004

This paper is to experimentally study on the sound absorption of a membrane resonance type system. Membrane resonance type system improves the weak point of a perforated plate system. The experimental results for a membrane resonance type system are explained in comparison with those of a perforated plate system. From the experimental results, it is found that there is an influence of the membrane on the absorption performance. The sound absorbing performances of a membrane resonance system are similar to those of a perforated plate system.

• 한국지반신소재학회논문집
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• 제3권2호
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• pp.31-38
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• 2004

2종류 지오그리드의 장기안정성의 검토되었다. 멤브레인 연신형 지오그리드는 지수함수형 인장거동을, 섬유형 지오그리드는 파단점에 가까울수록 빠른 인장특성 증가를 나타내었다. 섬유형 지오그리드의 경우 가속 크리프 시험을 실시하였지만 멤브레인 연신형 지오그리드의 경우에는 열적특성 때문에 가속 크리프 시험을 실시할 수 없었다. 멤브레인 연신형 지오그리드의 크리프 변형률은 인장시험에 의한 극한변형률보다 훨씬 큰 값을 나타내었으며, 섬유형 지오그리드의 크리프 변형에 의한 감소인자는 멤브레인 연신형 지오그리드에 비해 작은 값을 나타내었다.

• Korean Membrane Journal
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• 제1권1호
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• pp.43-49
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• 1999

Separation of soluble oil was investigated during filtration of cutting oil emulsion using various commercial ultrafiltration membranes. The surface properties of membranes used were hydrophilic hydrophobic and modified surfaces by various surfactant pretreatments. Conditions varied include stirring speed transmeembrane pressure membrane type and surfactant type for pretreatment. The results give some indication of mechanisms occurring at the membrane surface. Surfactant pretreatments significantly improved water flux and UF flux of hydrophilic regenerated cellulose(up to 2.4x for YM100) and hydrophobic polysulfone (up to 2.2x for PTHK) membranes depending on surfactant type and operating conditions. The UF flux enhancement was attributed to membrane swelling and reduction of interfacial surface tension between oil droplets and membrane surface. unexpectedly the hydrophilic membranes revealed greater flux enhancement than the hydrophobic membranes. The results also showed a greater improvement in UF flux at lower operating pressure.

• 상하수도학회지
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• 제19권1호
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• pp.25-30
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• 2005

In order to decrease the high costs of membrane process, we have tried to develop two alternatives to membrane; a cartridge type filter and a metal membrane were tested for the high permeation flux with low cost and low energy. This research mainly focused on three points; 1) operation with high permeation flux by using of a cartridge type filter and a metal membrane, 2) removals of the filterable organic materials (FOC) by pretreatments for the membrane fouling control, and 3) advanced wastewater treatment by SMBR process with intermittent aeration and high MLSS. An Intermittently aerated membrane bioreactor using a submerged micro filter (cartridge type) was applied in laboratory scale for the advanced wastewater treatment. To minimize membrane fouling, intermittent aeration was applied inside of the filter with $3.0kg_f/cm^2$. The experiments was conducted for 6 months with three different HRTs (8, 10, 12 hr) and high MLSS of 6,000 and 10,000mg/L. The filtration process could be operated up to 50 days with permeation flux of 500LMH. Regardless of the operating conditions, more than 95% of COD, BOD and SS were removed. Fast and complete nitrification was accomplished, and denitrification was appeared to be the rate-limiting step. More than 75% T-N could be removed due to the endogenous denitrification. T-P removal efficiency was increased to 80% under the condition of MLSS 10,000mg/L.

• Journal of Pharmaceutical Investigation
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• 제29권4호
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• pp.343-348
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• 1999

The purpose of this study is to prepare the controlled release adhesive patch containing naproxen. Pressuresensitive adhesive (PSA)-type patch was fabricated by casting of polyisobutylene (PIE.) and mineral oil in toluene. Membrane-controlled release (MCR)-type patch was prepared by the attachment of the controlled release membrane on the PSAtype patch. The membrane was mainly composed of Eudragit, polyethylene glycol(PEG) and glycerin. The drug release profile and skin permeation test with various patches were evaluated in vitro. The release of naproxen from PIE-based PSAtype patch with various loading doses fitted Higuchi's diffusion equation. However, the permeation of naproxen through hairless mouse skin from PSA-type patch followed zero-order kinetics. In MCR-type patch, thickness of controlled release membrane affected on the drug release rate highly. In the composition of membrane, the release rate was decreased as the ratio of Eudragit increased. The drug release from the MCR-type patch followed zero order kinetics. The permeation of naproxen through hairless mouse skin from MCR-type patch showed lag time for the intial release period and didn't fit the zero-order kinetics

• 한국지반신소재학회논문집
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• 제4권3호
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• pp.11-19
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• 2005

2가지 형태의 지오그리드의 장기안정성을 평가하였다. 멤브레인 연신형 지오그리드는 지수함수 형 인장특성을 나타내었으며 섬유형 지오그리드는 파단점에 근접할수록 빠른 인장특성의 증가를 나타내었다. 단기 가속 크리프 시험은 섬유형 지오그리드에는 실시되었지만 멤브레인 연신형 지오그리드의 경우 열적특성 때문에 실온에서만 실시 하였다. 멤브레인 연신형 지오그리드의 크리프 변형률은 인장시험에 의한 극한 인장변형률보다 크게 나타났다. 섬유형 지오그리드의 크리프 변형에 의한 감소인자는 멤브레인 연신형 지오그리드보다 작게 나타났다. 이 결과로부터 섬유형 지오그리드가 멤브레인 연신형 지오그리드보다 크리프 변형에 안정성이 있음을 알 수 있었다.