• 멤브레인
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• 제33권6호
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• pp.390-397
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• 2023

석유기반 플라스틱의 대체제인 폴리하드록시부틸레이트(polyhydroxybutyrate, PHB)의 기존 추출방법은 분자량 감소 및 물성 변형을 일으킨다. 본 연구에서는 기능화 된 탄소나노튜브(carbon nanotube, CNT)를 부착한 돌기형 탄소나노튜브 분리막의 여과를 통해 물리적 파쇄를 발생시켜 미생물 내 축적된 PHB를 추출하고자 하였다. 돌기형 탄소나노튜브 분리막의 물리적 파쇄를 확인하기 위해 대장균 용액으로 여과 실험을 수행하여 불활성화를 관찰하였다. 또한 PHB를 축적한 미생물 용액의 여과를 수행하여 PHB가 추출되었는지 확인하였더니 가장 대표적인 추출방법인 chloroform과 비교하여도 여과로 인한 추출이 4% 높은 성능을 가진 것을 관찰하였다. 본 결과를 통해 친환경적 바이오 플라스틱 회수를 위한 돌기형 탄소나노튜브 분리막의 적용 가능성을 확인하였다.

• Journal of Periodontal and Implant Science
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• 제41권5호
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• pp.253-258
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• 2011

Purpose: Immediate implantation presents challenges regarding site healing, osseointegration, and obtaining complete soft-tissue coverage of the extraction socket, especially in the posterior area. This last issue is addressed herein using the double-membrane (collagen membrane+high-density polytetrafluoroethylene [dPTFE] membrane) technique in two clinical cases of posterior immediate implant placement. Methods: An implant was placed immediately after atraumatically extracting the maxillary posterior tooth. The gap between the coronal portion of the fixture and the adjacent bony walls was filled with allograft material. In addition, a collagen membrane (lower) and dPTFE membrane (upper) were placed in a layer-by-layer manner to enable the closure of the extraction socket without a primary flap closure, thus facilitating the preservation of keratinized mucosa. The upper dPTFE membrane was left exposed for 4 weeks, after which the membrane was gently removed using forceps without flap elevation. Results: There was considerable plaque deposition on the outer surface of the dPTFE membrane but not on the inner surface. Moreover, scanning electron microscopy of the removed membrane revealed only a small amount of bacteria on the inner surface of the membrane. The peri-implant tissue was favorable both clinically and radiographically after a conventional dental-implant healing period. Conclusions: Secondary closure of the extraction socket and immediate guided bone regeneration using the double-membrane technique may produce a good clinical outcome after immediate placement of a dental implant in the posterior area.

• Membrane and Water Treatment
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• 제13권4호
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• pp.201-208
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• 2022

Emulsion Liquid Membrane (ELM) is a prominent technique for the separation of heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of the components (Surfactant and Carrier) of ELM is a very significant step for its preparation. In the ELM technique, the primary water- in-oil (W/O) emulsion is emulsified in water to produce water-in-oil-in-water (W/O/W) emulsion. The water in oil emulsion was prepared by mixing the membrane phase and internal phase. To prepare the membrane phase, the extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2- ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II). Emulsion Liquid Membrane (ELM) is a well-known technique for separating heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of ELM components (Surfactant and Carrier) is a very significant step in its preparation. In the ELM technique, the primary water-in-oil (W/O) emulsion is emulsified to produce water-in-oil-in-water (W/O/W) emulsion. The water in the oil emulsion was prepared by mixing the membrane and internal phases. The extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2-ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II).

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.109-122
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• 2018

This work highlights extraction and removal of Lignosulfonate using sunflower oil-Tri-n-octylamine (TOA) system in bulk liquid membrane transport. Maximum extraction and recovery percentages of 92.4% and 75.2% were achieved. Optimum manifold operating conditions were: 4 vol.% TOA, $2{\pm}0.1$ feed phase pH, 300 rpm stirring speed, at $40^{\circ}C$ with 0.2 (M) $Na_2SO_4$ solution. 1:2 (organic/aqueous) and 1:1 (aqueous/aqueous) phase ratios produced best results. Extraction (36.85 kJ/mol) was found to be intermediate controlled and stripping (54.79 kJ/mol) was chemical reaction controlled. Kinetic estimation of data with higher rate constants for stripping vis-${\grave{a}}$-vis extraction showed latter to be rate determining.

• 한국음향학회지
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• 제14권5호
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• pp.51-57
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• 1995

본 논문에서는 청각 모델을 기초로 잡음에 강한 음성 특징 추출을 연구하였다. 청각모델은 basilar membrane 모델, 섬모세포(hair cell) 모델과 스펙트럼 출력단으로 구성하였다. Basilar membrane 모델은 음파의 진동에 따른 전달 특성을 묘사한 것으로 대역 통과 필터의 열로 나타난다. 섬모 세포 모델은 basilar membrane의 진동에 의한 신경 물질로의 변환을 나타낸다. 이것은 입력의 상대적인 값에 크게 반응하는 adaptation 기능을 이용하게 되며, 잡음 제거에 중요한 역할을 하게 된다. 스펙트럼 출력 단은 각 채널의 평균 firing rate를 이용하여 mean rate spectrum을 형성한다. 그리고 mean rate spectrum을 이용하여 특징 벡터를 추출하였다. 실험 결과는 청각 구조에 기초한 특징 추출이 다른 특징 추출 방법에 비해 잡음에서 더 향상된 성능을 가짐을 보였다.

• Membrane and Water Treatment
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• 제6권2호
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• pp.95-102
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• 2015

The presented research is about characterization of Cellulose Triacetate (CTA) based Polymer Inclusion Membranes (PIMs) which incorporated the commercial extractant Aliquat 336, Tributylphosphate (TBP) as modifier and 2-Nitro Phenyl Pentyl Ether (NPPE) as plasticizer, for the preparation of the membranes. Chemical and physical characteristics of the synthesized membranes especially membrane thickness and side difference effects were investigated. Different surface structures and membrane thickness affect the extraction efficiency of membranes. Membrane extraction experiments were studied where the glass-facing surface of the membranes placed next to feed phase and the air-facing surface to stripping phase. The membrane was characterized by means of AFM, FT-IR and SEM.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제41권4호
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• pp.194-197
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• 2015

The amniotic membrane is the innermost layer of fetal membrane and is attached to the chorion in the placenta. This membrane has been used for nearly a century in varied fields such as ophthalmology, reconstructive surgery, and burn treatment. In this case report, we used a human amniotic membrane to repair an iatrogenic oroantral communication that occurred during the extraction of the patient's right upper second molar. A splint was given after the perforation was covered with human amniotic membrane and healing was clinically evaluated at various intervals. The outcome of the study revealed that the human amniotic membrane was an efficient graft material for repairing the defect caused by an iatrogenic oroantral communication following tooth extraction.

• Membrane and Water Treatment
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• 제4권1호
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• pp.11-25
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• 2013

Emulsion liquid membrane (ELM) process suffers from emulsion instability problem. So far, emulsion produced by mechanical methods such as stirrer and homogenizer has big size and high emulsion breakage. This paper discussed the application of emulsion produced by sonicator to extract cadmium in a batch ELM system. The emulsions consist of N,N-Dioctyl-1-octanamine (trioctylamine/TOA), nitrogen trihydride (ammonia/NH4OH), sorbitan monooleate (Span 80), and kerosene as carrier, stripping solution, emulsifying agent, and organic diluent, respectively. Effects of comprehensive parameters on extraction efficiency of Cd(II) such as emulsification time, extraction time, stirring speed, surfactant concentration, initial feed phase concentration, carrier concentration, volume ratio of the emulsion to feed phase, and pH of initial feed phase were evaluated. The results showed that extraction efficiencies of Cd(II) greater than 98% could be obtained under the following conditions: 15 minutes of emulsification time, 4 wt.% of Span 80 concentration, 4 wt.% of TOA concentration, 15 minutes of extraction time, 250 rpm of stirring speed, 100 ppm of initial feed concentration, volume ratio of emulsion to feed phase of 1:5, and initial feed pH of 1.53.

• 멤브레인
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• 제21권2호
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• pp.171-176
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• 2011

분리막을 이용한 수처리 공정에서 유입 수에 함유된 부유물질이나 기타 오염물질이 막 표면 또는 내부에 축적 흡착 등의 막 오염현상으로 인해 막 성능 감소와 함께 막 분리 공정에 큰 영향을 미치게 된다. 본 연구에서는 막 표면에서의 막 오염현상을 실시간으로 모니터링 할 수 있는 기술을 연구하였다. 투명한 오염물질에 의한 분리막 표면 오염을 측정하기 위해 막 표면에 360 nm 파장의 가시광선을 조사하여 이미지를 R. G. B 값으로 추출하여 막의 오염현상을 실시간으로 모니터링 하였다. 추출된 이미지 중 400~499 nm 파장영역인 B 값이 가장 강도가 강하게 나타났다. 막 오염정도의 변화를 이미지의 강도 차이로 관찰함으로써 실시간 분석이 가능함을 확인하였다.

• Journal of Periodontal and Implant Science
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• 제39권3호
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• pp.367-373
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• 2009

Purpose: Following tooth extraction caused by severe periodontitis, alveolar ridge dimension lose their original volume. To reduce the alveolar ridge dimension, the ridge preservation technique has been introduced and tested in many clinical studies with membrane alone or membrane plus graft, achieving reduced ridge loss compared to extraction only. The aim of the present clinical study was to compare the post-extraction dimensional changes in the membrane exposure group to non-exposure group during healing period following ridge preservation technique. Methods: Ridge preservation was performed in 44 extraction sites. After extraction, deproteinized bovine bone mineral coated with synthetic oligopeptide (Ossgen-$X15^{(R)}$) or deproteinized bovine bone mineral (Bio-$Oss^{(R)}$) was implanted into the socket. A collagen membrane (Bio-$Gide^{(R)}$) was trimmed to cover the socket completely and applied to the entrance of the socket. Four clinical parameters were compared between baseline and 6 months. Results: During healing period, membrane exposure was observed at 19 sites. At the re-entry, hard newly formed tissue were observed at the ridge preservation site. The grafted socket sites were well preserved in their volume dimension. In both groups, horizontal ridge width was reduced and vertical height was increased. There were not statistically significant differences in horizontal (-1.32 mm vs -1.00 mm) and vertical ridge change (2.24 mm vs 2.37 mm at buccal crest, 1.36 mm vs. 1.53 mm at lingual crest) between two groups. Conclusions: The ridge preservation approach after tooth extraction effectively prevented resorption of hard tissue ridge in spite of membrane exposure during healing period.