• Membrane Journal
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• v.26 no.5
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• pp.372-380
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• 2016

The present paper reports the effect of precursor alumina particle size on pore structure and single gas permeation properties of tubular ${\alpha}$-alumina supports, prepared by a combined process of slip casting and sintering. Pore diameter of as-prepared ${\alpha}$-alumina support was highly dependent on precursor ${\alpha}$-alumina particle size. Although, increase in the precursor particle size increases the pore diameter, but the porosity of ${\alpha}$-alumina support mainly control by sintering temperature. Sintering studies reveal that as sintering temperature increased porosity of support decreased. Single gas permeance results indicate that permence is proportional to the square of pore diameter and linearly to porosity. These dependencies revealed that gas permeation trough as-prepared ${\alpha}$-alumina support was governed by viscous flow mechanism. The present announces that precursor ${\alpha}$-alumina particle size and sintering temperature are key parameters to control gas permeantion properties of ${\alpha}$-alumina supports.

• Polymer(Korea)
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• v.32 no.6
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• pp.516-522
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• 2008

Biodegradable polymers have been used extensively as scaffolding materials to regenerate new tissues and the ingrowth of tissue have been reported to be dependent directly of the porosity, pore diameter, pore shape, and porous structure of the scaffold. In this study, porous poly (L-lactide-co-glycolide) (PLGA) scaffolds with five different pore sizes were fabricated to investigate the effect of pore sizes for AF tissue regeneration. Cellular viability and proliferation were assayed by MTT test. Hydroxyproline/DNA content of AF cells on each scaffold was measured. sGAG analyses were performed at each time point of 2 and 6 weeks. Scaffold seeded AF cells were implanted into the back of athymic nude mouse to observe the difference of formation of disc-like tissue depending on pore size in vivo. We confirmed that scaffold with $180{\sim}250{\mu}m$ pores displayed high cell viability in vitro and produced higher ECM than scaffold with other pore sizes in vivo.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.691-695
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• 2005

Zeolite membranes on various supports such as filter paper, cotton fiber, and glass fiber filter were prepared by secondary growth hydrothermal synthesis. First, zeolite NaA (${\approx}0.5{\mu}m$) and silicalite-1 (${\approx}0.2{\mu}m$) crystals were synthesized as zeolite seed crystals, and they were attached to the surfaces of the supports via chemical bonding. Zeolite NaA or silicalite-1 membranes could be synthesized on the supports coated with the seed crystals. The prepared zeolite membranes were observed by scanning electron microscope and analyzed by X-ray diffraction.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.536-540
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• 2020

The support of the PEMFC membrane plays a key role in improving mechanical durability. The e-PTFE used as a support is chemically stable, so electro-chemical degradation in the PEMFC driving process has been rarely studied. In this study, we investigated whether e-PTFE is chemically stable to radicals and hydrogen peroxide during Fenton reaction. After the Fenton reaction, the main chain of e-PTFE broke, resulting in a change in the chemical structure and morphology of the support, resulting in a decrease in tensile strength. The results of this study showed that electrochemical degradation of the membrane ionomer in the PEMFC process occurs inside the membrane by radicals and hydrogen peroxide, so that electrochemical degradation may also occur at the e-PTFE support in the cell.

• Polymer(Korea)
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• v.25 no.3
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• pp.318-326
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• 2001

PLLA scaffold loaded with gentamicin sulfate (GS) was prepared by emulsion freeze-drying method for the prevention of infection and the improvement of wettability. i.e., the cell- and tissue-compatibility. GS-loaded PLLA scaffolds were characterized by scanning electron microscopy (SEM), mercury porosimetry and blue dye intrusion, and the GS release pattern was analyzed by high performance liquid chromatography (HPLC). GS-loaded PLLA scaffolds with porosity above 50%, medium pore size ranging from 30 to 57 ${\mu}{\textrm}{m}$ (with larger pore diameters greater than 150 ${\mu}{\textrm}{m}$), and specific pore area in the range of 35 to 75($m^2$ /g )were manufactured by varying processing parameter as GS concentration. It was observed that GS-loaded PLLA scaffolds were highly porous with good interconnections between pores for allowing cell adhesion and growth. These scaffolds may be applicable for scaffold as structures that facilitate either tissue regeneration or repair during reconstructive operations.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.1
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• pp.51-62
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• 2000

핵연료집합체 검증 프로그램의 일환으로 본 연구에서는 지진과 배과파단이 핵연료집합체의 건선성에 미치는 영향을 검토하였다 원자로 노심의 상세 동적해석을 이용하여 지진 및 배과파단시 핵연료 집합체에 발생하는 전단력 굽힘 모우멘트 및 변위를 계산하였고 또한 집합체를 지지하고 있는 지지격자체의 충격력을 검토하였다 이들 하중에 대한 핵연료집합체의 응력해석을 수행하여 사고조건하에서의 구조적 건전성에 대하여 언급하였고 추후 설계시 고려할 사항을 제시하였다.

• Polymer(Korea)
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• v.32 no.2
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• pp.163-168
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• 2008

Biomedical scaffold for tissue regeneration was fabricated by one of rapid prototyping processes, bioplotting system, with a biodegradable and biocompatible poly($\varepsilon$-carprolactone)(PCL). Through dynamic mechanical test, it was observed that the PCL scaffold manufactured by the bioplotting process has the superior mechanical properties compared to the conventional scaffold fabricated by a salt-leaching process, and the plotted scaffold could be employed as a potential scaffold to regenerating hard and soft tissue. The plotted scaffold was consisted of porous structures. which were interconnected with each pore to help cells be easily adhered and proliferated in the wall of pore tunnels, and metabolic nutrients can be transported within the matrix. By using the plotting system, we could adjust the pore size, porosity, strand pitch, and, strand diameter of PCL scaffolds, which were important parameters to control mechanical properties of the scaffolds, and consequently we could determine that the mechanically controlled scaffolds could be used as a matching scaffold for any required mechanical properties of the target organ. The fabricated 3D PCL scaffold showed enough possibility as a 3D biomedical scaffold, which was cell-cultured with chondrocytes.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.659-664
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• 2000

To develop anode-supported tubular cell with proper porosity, we have investigated the anode substrate and t the electrolyte-coated anode tube. The anode substrate was manufactured as a function of carbon content in the range of 20 to 50 vol.%. As the carbon COntent increased, the porosity of the anode substrate increased slightly and the carbon c content with proper porosity is found to be 30 vol.%. The anode-supported tube was fabricated by extrusion process a and the electrolyte layer was coated on the anode tube by slurry coating process. The anode-supported tube was cofired successfully at $^1400{\circ}C$ in air. The porosity of the anode tube was 35%. From the gas permeation test, the anode t tube was found to be porous enough for gas supply. On the other hand, the anode-supported tube with electrolyte layer indicated a very low gas permeation rate. This means that the coated electrolyte was dense.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.261-261
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• 2009

Anode 지지형 SOFC의 Anode 지지층 제조에 있어 Ni의 입성장이 일어나면 전극의 반응면적이 줄어들어 전기전도도가 감소되므로 소결체의 제조공정이 매우 중요하다. 기공형성제의 함량이 증가할수록 기공율도 증가하였고 기공체의 함량이 20%를 넘어가면서 기공율은 오히려 줄고 밀도도 감소하였다. Anode 지지체는 $1200^{\circ}C$ 이상에서 열처리하여야 입자간 소결이 이루어지며 승온 속도를 $2.5^{\circ}C$ 유지하여 20% 수준의 기공률을 형성하였다. 소결한 음극지지체를 환원하였을 때 35%수준의 개기공을 형성하였고 전해질과의 접착성도 우수하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1229-1235
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• 2015

Scaffold fabrication technology using a 3D printer was developed for damaged bone tissue regeneration. A scaffold for bone tissue regeneration application should be biocompatible, biodegradable, and have an adequate mechanical strength. Moreover, the scaffold should have pores of satisfactory quantity and interconnection. In this study, we used the polymer deposition system (PDS) based on fused deposition modeling (FDM) to fabricate a 3D scaffold. The materials used were polycaprolactone (PCL) and alginic acid sodium salt (sodium alginate, SA). The salt-leaching method was used to fabricate dual pores on the 3D scaffold. The 3D scaffold with dual pores was observed using SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) and evaluated through in-vitro tests using MG63 cells.