• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.34-35
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• 1994

Tube-in-orifice형태의 spinneret을 제작하여, polyethersulfone을 재질로 하는 capillary membrane을 건습식방사공정을 통해 제조하였다. 기공형성계는 PVP를, 용매는 NMP/DCM을, 내부응고제는 물과 NMP의 혼합물을, 외부응고제는 냉각수를 사용하였다. 내부응고제의 NMP농도에 따른 막의 형태와 microstructure를 연구하였다. 내부응고제가 약한 응고력을 가질 때 macrovoid가 없고, 내부의 활성층이 치밀한 막을 얻을 수 있었다. PES-NMP/DCM-PVP조성(25-44/11-20)의 용액으로, 40% NMP수용액을 내부응고제로 사용하여, 막을 제조하고 이를 모듈화하여, 한외여과실험을 한 결과, MWCO 8,000인 모듈이 얻어졌으며, 이 모듈의 Flux는 1기압에서 $1.44 \times 10^{-5}m/sec$이었다.

• Membrane Journal
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• v.15 no.4
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• pp.272-280
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• 2005

In this study, asymmetric polysulfone membranes were prepared by the phase inversion method and the casting solutions were containing N-methyl-2-pyrrolidone (NMP) as a solvent. Deionized water and various alcohols(methanol, ethanol, and propanol) were used as a coagulation medium in preparing asymmetric polysulfone membranes. This study investigates the effect of alcohol coagulants having different solubility parameters as a pore-former on the construction of porous structures and their pure water permeation properties. Asymmetric polysulfone membranes immersed in the pure alcohol coagulation bath solution showed the typical sponge-like structures and the reduced water permeability as compared with those of polysulfone membranes precipitated in the pure water coagulation bath solution. In the water/alcohol mixtures, asymmetric polysulfone membranes showed the finger-like structures with the sponge-like structures. Therefore, the sponge-like structure of polysulfone membrane was formed under the delayed demixing systems while the porosity of membrane was decreased significantly. The water permeability of polysulfone membrane precipitated in the pure water coagulant showed 164 [$L/m^2hr$] at 14.7 psi. In case of polysulfone membranes prepared in the pure methanol and ethanol coagulant, they showed the water permeability of 56 and 30 [$L/m^2hr$], respectively.

• Membrane Journal
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• v.27 no.4
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• pp.350-357
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• 2017

In this study, we used TIPS (thermally induced phase separation) for the application of water treatment membrane, and observed the change in morphology of separation membrane due to the change of solidification temperature and heat capacity. For manufactured membrane, PVDF and silica with excellent mechanical properties and chemical resistance were used, and DOP (dioctyl phthalate), DBP (dibutyl phthalate) were used as the diluent. Using the SEM (scanning electron microscope), the morphology of each different coagulation solutions of heat capacity change was observed. As the heat capacity increased, the crystallization rate of PVDF was decreased and showed large pore. In contrast, It also confirmed that the smaller heat capacity, the faster the crystallization rate and make smaller pores.

• Membrane Journal
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• v.27 no.5
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• pp.458-467
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• 2017

In this study, we prepared PVDF membranes via TIPS for water treatment applications. PVDF was used for its excellent chemical and mechanical properties. The effect of coagulation bath composition, temperature, and heat capacity on the overall membrane morphology was studied and observed using SEM. A mixture of DOP and DBP was used as the diluent, and silica was used as an additive. It was observed that as the heat capacity of the coagulation bath increased, the crystallization rate of PVDF decreased yielding larger pores. Also, as the heat capacity of the coagulation bath decreased, the crystallization rate of PVDF increased yielding smaller pores.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.919-928
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• 2010

Four patterns for width adjustment were studied with an aim to increase the width-adjustment speed in continuous casting. The main goals are to minimize the actuating force of a WAM actuator, to develop a deformation analysis model of a solidified shell in the mold, and to induce the main limit factor for the speedup of width adjustment. On the basis of the width-adjustment experiment, the notable features of four patterns types were considered, and we compared the corresponding actuating forces. For comparing the driving forces of the patterns, during the experiment, the same casting speed was maintained for each pattern. To optimize the parameter of the deformation analysis model of the solidified shell, the experiment results were applied to them. To speed up width adjustment and to reduce the driving force, we controlled the pattern parameters. The most effective pattern was the fast-mode pattern, and the taper was the main parameter that helped reduce the driving forces during the motion of the actuator.

• Membrane Journal
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• v.15 no.3
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• pp.233-240
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• 2005

Surface modification of polypropylene hollow fiber membranes was performed in order to develop blood-compatibility biomaterials for use in the blood contacting surfaces and oxygenation membranes of a lung assist device (LAD), important medical device even more useful. Blood compatibility of materials was determined by using anticoagulation blood and evaluating formation of blood clots on their surfaces as well as activation of plasma coagulation cascade, platelet adhesion, and aggregation. It was verified that the number of platelets on the silicone coated fibers was significantly lower than that on untreated fiber membrane, indicating improved blood compatibility. It was also found that the polypropylene hollow fiber membranes using plasma treatment exhibited suppression of complement activation in blood compatibility test.

• Polymer(Korea)
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• v.25 no.2
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• pp.151-160
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• 2001

Polymeric membranes consisting of poly(d,1-lactide) as a polymer matrix and crystallizable progesterone as a drug were prepared by coagulating polymeric solutions. The homogeneous casting solutions in dimethyformamide were solidified by using three different coagulating processes : solvent evaporation under vacuum, solvent extraction via immersion into the nonsolvent bath, or vapor exposure at high humidity condition. With solvent removal via evaporation under vacuum, the cast solution film was vitrified to form a homogeneous film containing progesterone of spherical shape distributed evenly in the film. Being prepared by solvent extraction via immersion into a water bath, the resulting membrane showed an asymmetric structure, with progesterone of big crystallites distributed unevenly in the structure. On the other hand, the coagulation under high humidity transformed the cast film into a sponge-like structure, where progesterone took a shape like flake.

• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.3
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• pp.87-95
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• 1980

일정한 압력으로 유지한 수직관속을 흐르는 유체의 응고에 관한 현상을 이론적으로 규명하고, 이미 얻은 실험 결과와 비교함으로서 그 정확성을 검토하였다. 관속을 흐르는 유체가 얼어서 완전히 관을 막을 때까지 요하는 시간을 산출하는 공식을 유도 하였으며, 관이 완전히 막힐 때 까지 흘러내리는 유체의 양을 추정하는 방법도 제시하였다. 본 연구에서 제시한 공식의 적용 가능범위도 아울러 검토하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.04a
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• pp.36-37
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• 1993

상전이 공정에 의해 제조된 기체분리용 중공사막은 1차적으로 방사원액의 조성과 내.외부응고제의 조성, 중공사 방사조건 그리고 후처리 과정에 의해서 전체적인 구조가 결정되어진다. 특히 기체 분리에 이용되는 Nonprous Membrane의 경우 Dense Skin의 Thickness와 Pinhole의 유무에 따라 투과성과 선택성에 커다란 영향을 미친다. 따라서 최근에는 Dense Skin의 초박막화와 Pinhole이 없는 비대칭막 제조등 폭넓은 연구가 이루어지고 있다. 본 연구에서는 CO$_2$ Gas 분리용 Polyetherimide 중공사막을 제조하여, 중공사막 제조조건과 후처리 조건에 따른 $CO_2/N_2$ Gas의 분리계수를 측정하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.93-95
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• 1998

1. 서론 : 폴리이미드계 고분자는 기계적 성질과 내열성이 우수한 고분자 소재이다. 일반적으로 기체분리막으로서의 유리상 고분자는 기체의 투과성은 결여되지만, 고분자쇄의 동결속박에 의한 자유부피에 따라 기체의 선택성이 높게 나타난다. 본 연구에서는 고분자로서 polyetherimide(PEI) 를 이용하여 제막조건(고분자 농도, air gap, 용매, 내부응고제 주입량 등)을 달리하는 중공사막을 제조하여, 제막변수에 따른 막의 구조 및 기체투과 특성을 검토하였다.