• 설비공학논문집
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• 제20권4호
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• pp.274-279
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• 2008

In the perspective of saving energy in buildings, high performance of insulation and air tightness for improving the heating and the cooling efficiency has brought the positive effect in an economical view. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and it is also very harmful to residents because they spend over 90% of their time in the indoor area. Therefore, the ventilation is important to keep indoor environment clean and it can also save energy consumption. In this study, a HEPA type breathing wall is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. To make fine porous structures, polymer nano fibers which were made by electro spinning method are used as a precursor. The nano fibers are coated with SiO2 nano particles and finally the HEPA type breathing wall is made by sintering in the electric furnace at $300\sim500^{\circ}C$. The pressure drops of nano ceramic structure are 8.2, 25.5 and 44.9 mmAq at the face velocity of 2.0, 5.9 and 8.8 cm/s, respectively. Also the water vapor permeability is $3.6g/m^2{\cdot}h{\cdot}mmHg$. In this research, the porous nano ceramic structures are obtained and the possibility for the usage of a material for HEPA type breathing wall can be obtained.

• 한국세라믹학회지
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• 제45권2호
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• pp.132-137
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• 2008

The main purpose of this study is enhancing the filtering efficiency, performance and durability of filter by growing SiC whiskers on cordierite honeycomb substrate. The experiment was performed by Chemical Vapor Infiltration (CVI) in order to control pore morphology of substrate. Increasing the mechanical strength of porous substrate is one of important issues. The formation of "networking structure" in the pore of porous substrate increased mechanical strength. The high pressure gas injection to the specimen showed that a little of whiskers were separated from substrate but additional film coating enhanced the stability of whisker at high pressure gas injection. Particle trap test was performed. More nano-particle was trapped by whisker growth at the pore of substrate. Therefore it is expected that the porous cordierite which deposited the SiC whisker will be the promising material for the application as filter trapping the nano-particles.

• 한국결정성장학회지
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• 제29권6호
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• pp.352-358
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• 2019

최근 인쇄용지는 단순히 정보 전달의 기능을 넘어서 미적, 예술적 가치가 부가면서 고품질의 인쇄가 가능한 도공지(coated paper)에 대한 시장의 수요가 증가하고 있다. 특히 실사급 고품질의 인쇄가 가능한 잉크젯 프린팅의 도공지는 잉크의 인쇄적성을 향상시키기 위하여 표면에 젖음성(wettability)과 다공성 구조(porous structure)를 갖는 도공층의 역할이 매우 중요하다. 본 연구에서는 나노 실리카 졸 입자에 실란 커플링제로 표면처리하고 수용성 결합제인 폴리비닐알콜(PVA)와 혼합하여 도공액(coating color)를 제조하고 원지(base paper)에 코팅하여 도공층을 제조하였다. 실란 커플링제로 표면처리한 나노 실리카 도공층은 표면처리하지 않은 도공층과 비교하여 균일한 기공 분포 및 평탄한 표면 거칠기를 가지며, 판매용 고급 인화지와 유사한 광택도를 갖는 것을 확인하였다. 특히 잉크의 망점(dot)에 대한 진원도로 평가하는 인쇄적성 평가 결과 실란 커플링제로 표면처리한 도공지는 다층 구조의 도공층을 갖는 판매용 고급 인화지보다 더 우수한 결과를 얻을 수 있었다. 이러한 결과는 실란 커플링제 표면처리를 통하여 나노 실리카 입자의 분산성이 향상되어 우수한 젖음성과 균일한 기공 분포를 갖는 도공층 형성이 가능하였기 때문으로 확인되었다.

• 한국세라믹학회지
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• 제50권4호
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• pp.301-307
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• 2013

SiC hollow fiber was fabricated by curing, dissolution and sintering of Al-PCS fiber, which was melt spun the polyaluminocarbosilane. Al-PCS fiber was thermally oxidized and dissolved in toluene to remove the unoxidized area, the core of the cured fiber. The wall thickness ($t_{wall}$) of Al-PCS fiber was monotonically increased with an increasing oxidation curing time. The Al-PCS hollow fiber was heat-treated at the temperature between 1200 and $2000^{\circ}C$ to make a SiC hollow fibers having porous structure on the fiber wall. The pore size of the fiber wall was increased with the sintering temperature due to the decomposition of the amorphous $SiC_xO_y$ matrix and the growth of ${\beta}$-SiC in the matrix. At $1400^{\circ}C$, a nano porous wall with a high specific surface area was obtained. However, nano pores grew with the grain growth after the thermal decomposition of the amorphous matrix. This type of SiC hollow fibers are expected to be used as a substrate for a gas separation membrane.

• 한국세라믹학회지
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• 제46권3호
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• pp.249-252
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• 2009

Nanocrystalline ceria particles were prepared by using the ultrasonic spray pyrolysis method. The prepared ceria particles were found to be spherical and non-agglomerated by the SEM and TEM analyses. It was found that carrier gas influences the size and morphology. It was found that the air stream of carrier gas results in porous agglomerated structure of ceria abrasives, whereas solid nano-sphere can be obtained in a more oxidizing atmosphere.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.7.2-7.2
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• 2009

Nanoporous bioactive glass(NBG) ceramic with well interconnected pore structures were fabricated bytriblock copolymer templating and sol-gel techniques. Hierarchically porous BGbeads were also successfully synthesized by controlling the condition of solvent.The beads have hierarchically nano- and macro-pore structure with a sizesbetween several tens nanometers and several hundred micrometers. Both NBG andBG beads show superior bone-forming bioactivity and good in vitrobiodegradability. Biocompatibility both in vitro and in vivo were examed andwas revealed that it largely relies on the pore morphology as well ascomposition. Our synthetic process can be adapted for the purpose of preparingvarious bioceramics, which have excellent potential applications in the fieldof biomaterials such as tissue engineering and drug storage.

• 한국결정성장학회지
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• 제15권4호
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• pp.168-174
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• 2005

건조공정 중인 다공성 물질의 물성은 재료의 비균질성 즉 전위, 입자, 입계, 균열, 기공과 같은 미시적인 결함 인자들의 영향을 받는다. 따라서 다공성 물질의 건조공정을 전산 시뮬레이션하기 위해서는 연속체 스케일과 원자 스케일해석 그리고 스케일별 해석 한계 극복이 요구된다. 본 연구에서는 분자동역학 시뮬레이션으로 계산한 나노스케일 물성를 연속체 스케일 해석에 연계하는 계층적 멀티스케일 시스템을 구축하고, 다공성 세라믹 애자의 건조공정을 전산 시뮬레이션 하였다. 해석 결과, 온도, 습도, 변형률 그리고 응력 분포를 기존의 결과들과 비교하여 검증하였다.

• 한국세라믹학회지
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• 제43권12호
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• pp.839-845
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• 2006

Graphite has hexagonal closed packing structure with two bonding characteristics; (1) van der waals bonding between c axis, and (2) covalent bonding in the a and b axis. The weak van der waals bonds cause self-lubricant property, and the strong covalent bonds cause excellent electric and thermal conductivity. Furthermore, graphite is chemically very inert because of the material composed of only carbon elements. Thus, graphite is very useful for mechanical sealing materials. However, Graphite have porous microstructure because starting materials of graphite produce many volatile during the manufacturing processes. This causes low density of graphite, which is unsuitable for the mechanical sealing materials. Thus, further impregnation process is generally needed to enhance the graphite density. In this work, high density graphite is prepared with the principle of densification when coke and pitch binder, prepared from thermal treatment of coal tar pitch, become dehydrogenation during graphitization or carbonization.

• 한국세라믹학회지
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• 제43권2호
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• pp.85-91
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• 2006

Electron Beam Physical Vapor Deposition (EB-PVD) was applied to fabricate a thin film YSZ electrolyte with large area on the porous NiO-YSZ anode substrate. Microstructural and thermal stability of the as-deposited electrolyte film was investigated via SEM and XRD analysis. In order to obtain an optimized YSZ film with high stability, both temperature and surface roughness of substrate were varied. A structurally homogeneous YSZ film with large area of $12\times12\;cm^2$ and high thermal stability up to $900^{\circ}C$ was fabricated at the substrate temperature of $T_s/T_m$ higher than 0.4. The smoother surface was proved to give the better film quality. Precise control of heating and cooling rate of the anode substrate was necessary to obtain a very dense YSZ electrolyte with high thermal stability, which affords to survive after post heat treatment for fabrication a cathode layer on it as well as after long time operation of solid oxide fuel cell at high temperature.

• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.117-122
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• 2010

BCY($Ba(Ce_{0.9}Y_{0.1})O_{3-\delta}$) oxide, shows high protonic conductivity at high temperatures, and are referred to as hydrogen separation membrane. For high efficiency of hydrogen separation ($H_2$ flux and selectivity) and low fabrication cost, ultimate thin and dense BCY-Ni layer have to be coated on a porous substrate such as $ZrO_2$. Aerosol depostion (AD) process is a novel technique to grow ceramic film with high density and nano-crystal structure at room-temperature, and would be applied to the fabrication process of AD integration ceramic layer effectively. XRD and SEM measurements were conducted in order to analyze the characteristics of BCY-Ni membrane fabricated by AD process.