• 한국세라믹학회지
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• 제41권8호
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• pp.628-632
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• 2004

생체친화성 인공골 개발을 위하여 해면골과 매우 유사한 기공구조를 갖는 천연 산호(CaCO$_3$, aragonite phase)를 수열처리하여 수산화아파타이트 다공체를 제조하였다. 생체 친화성을 증진시키기 위하여 산호를 수열 처리하는 과정에서 실리콘을 치환시키는 실험을 하였다. 수열합성과 solvothermal 방법을 반복적으로 사용하여 실리콘이 치환된 수산화아파타이트를 합성하였으며 이들의 각 온도에 따른 상변화 및 실리콘 농도를 XRD, ICP, EDS 등을 통하여 분석하였다. 분석결과로부터 실리콘이 수산화아파타이트 골격 내에 균일하게 분산되어 있음을 확인하였다.

• 대한전자공학회논문지SD
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• 제39권4호
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• pp.19-25
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• 2002

본 논문에서는 실리콘 기판상의 전송선로 특성을 개선하기 위하여 표면 마이크로머시닝 기술을 이용하여 10㎛ 두께의 다공질 실리콘 산화막으로 제조된 기판 위에 air-bridge interconnect된 CPW 전송선로를 제작하였다. 간격이 30㎛ 신호선이 80㎛인 CPW air-bridge 전송선의 삽입손실은 4㎓에서 -0.25 ㏈이며, 반사손실은 -28.9 ㏈를 나타내었다. S-W-S = 30-100-30 ㎛인 stepped compensated air-bridge를 가진 CPW는 손실이 4㎓일 때, -0.98 ㏈ 개선됨을 알 수 있었다. 이와 같은 결과로부터 두꺼운 다공질 실리콘은 고 저항 실리콘 집적회로 공정에서 고성능, 저가의 마이크로파 및 밀리미터파 회로 응용에 충분히 활용 될 수 있으리라 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2410-2412
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• 2005

In this study, two types of PS substrate were fabricated for sensing of chemical and biological substances. For sensing of the humidity and chemical analyzes such as $CH_3OH$ or $C_2H_5OH$, PS layers are prepared by photoelectrochemical etching of silicon wafer in aqueous hydrofluoric acid solution. To evaluate their sensitivity, we measured the resistance variation of the PS diaphragm. As the amplitude of applied voltage increases from 2 to 6Vpp at constant frequency of 5kHz, the resistance variation for humidity sensor rises from 376.3 to $784.8{\Omega}$/%RH. And the sensitivities for $CH_3OH$ and $C_2H_5OH$ were 0.068 uA/% and 0.212 uA/%, respectively. For biological sensing application, amperometric urea sensors were fabricated based on porous silicon(PS), and planar silicon(PLS) electrode substrates by the electrochemical methods. Pt thin film was sputtered on these substrates which were previously formed by electrochemical anodization. Poly (3-methylthiophene) (P3MT) were used for electron transfer matrix between urease(Urs) and the electrode phase, and Urs also was by electrochemically immobilized. Effective working area of these electrodes was determined for the first time by using $Fe(CN)_6^{3-}/Fe(CN)_6^{4-}$ redox couple in which nearly reversible cyclic voltammograms were obtained. The $i_p$ vs $v^{1/2}$ plots show that effective working electrode area of the PS-based Pt thin film electrode was 1.6 times larger than the PLS-based one and we can readily expect the enlarged surface area of PS electrode would result in increased sensitivity by ca. 1.6 times. Actually, amperometric sensitivity of the Urs/P3MT/Pt/PS electrode was ca 0.91uA/$mM{\cdot}cm^2$, and that of the Urs/P3MT/Pt/PLS electrode was ca. 0.91uA/$mM{\cdot}cm^2$ in a linear range of 1mmol/L to 100mmol/L urea concentrations

• 한국세라믹학회지
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• 제47권6호
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• pp.546-552
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• 2010

The achievement of high gas permeability is a key factor in the development of porous SiC ceramics for applications of hot gas filter, vacuum chuck, and air spindle. However, few reports on the gas permeability of porous SiC ceramics can be found in the literature. In this paper, porous SiC ceramics were fabricated at temperatures ranging from $1600^{\circ}C$ to $1800^{\circ}C$ using the mixing powders of SiC, silicon, carbon and boron as starting materials. In some samples, expanded hollow microspheres as a pore former were used to make a cellular pore structure. It was possible to produce Si bonded SiC ceramics with porosities ranging from 42% to 55%. The maximum bending strength was 58MPa for the carbon content of 0.2 wt% and sintering temperature of $1700^{\circ}C$. The increase of air permeability was accelerated by addition of hollow microsphere as a pore former.

• 한국분말재료학회지
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• 제24권1호
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• pp.24-28
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• 2017

Silicon alloys are considered promising anode active materials to replace Li-ion batteries by graphite powder, because they have a relatively high capacity of up to 4200 mAh/g, and are environmentally friendly and inexpensive ECO-materials. However, its poor charge/discharge properties, induced by cracking during cycles, constitute their most serious problem as anode electrode. In order to solve these problems, Si-Ge-Al alloys with porous structure are designed as anode alloy powders, to improve cycling stability. The alloys are melt-spun to obtain the rapidly solidified ribbons, and then ball-milled to make fine powders. The powders are etched using 1 M HCl solution, which gives the powders a porous structure by removing the element Al. Subsequently, in this study, the microstructures and the characteristics of the etched powders are evaluated for application as anode materials. As a result, the etched porous powder shows better electrochemical properties than as-milled Si-Ge-Al powder.

• 한국재료학회지
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• 제22권1호
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• pp.8-15
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• 2012

Silicon-based thin film was prepared at room temperature by an electrochemical deposition method and a feasibility study was conducted for its use as an anode material in a rechargeable lithium battery. The growth of the electrodeposits was mainly concentrated on the surface defects of the Cu substrate while that growth was trivial on the defect-free surface region. Intentional formation of random defects on the substrate by chemical etching led to uniform formation of deposits throughout the surface. The morphology of the electrodeposits reflected first the roughened surface of the substrate, but it became flattened as the deposition time increased, due primarily to the concentration of reduction current on the convex region of the deposits. The electrodeposits proved to be amorphous and to contain chlorine and carbon, together with silicon, indicating that the electrolyte is captured in the deposits during the fabrication process. The silicon in the deposits readily reacted with lithium, but thick deposits resulted in significant reaction overvoltage. The charge efficiency of oxidation (lithiation) to reduction (delithiation) was higher in the relatively thick deposit. This abnormal behavior needs to clarified in view of the thickness dependence of the internal residual stress and the relaxation tendency of the reaction-induced stress due to the porous structure of the deposits and the deposit components other than silicon.

• 한국세라믹학회지
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• 제45권9호
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• pp.497-506
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• 2008

The long time of twenty years has passed since Diesel Particulate Filter (DPF) was proposed before the practical use. The main factors that DPF has been put to practical use in this time, are the same time proposal of the evaluation method of SiC porous materials linked to he performance on the vehicle, and that the nature of thermal shock required for the soot regeneration (combustion of soot) in the DPF is different from the conventional requirement for the rather rapid thermal shock. For the requirements, these includ demonstrating utmost the characteristic of SiC's high thermal conductivity, and overcoming the difficulty of thermal expansion of SiC-DPF by dividing the filter into segments binding with the cement of lower Young's modulus, and the innovation of technology around the diesel exhaust system such as Common-Rail system. As the results of these, the cumulative shipments of SiC-DPF have reached about 5 million, and it goes at no claim in the market.

• 한국결정성장학회지
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• 제8권1호
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• pp.124-130
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• 1998

양극반응 전류밀도를 변화시키면서 다공질 규소를 제작하여 라만산란을 관측하였다. 전류밀도가 증가함에 따라 라만신호는 520.5$\textrm{cm}^{-1}$에서 멀어졌으며, 봉우리의 반치폭이 증가하였다. 또한 전류밀도 증가에 따라 원통형 다공질 결정의 직경은 감소함이 계산되었으며, 길이가 길어짐을 AFM으로 관찰하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1009-1010
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• 2006

In this study, we attempt to synthesize the cordierite from the reaction of fly-ash, alumina, silicon dioxide, and magnesia powders. For the purpose of air purification, the honeycomb filter with porous cordierite was fabricated from the combination of synthetic cordierite and pore forming agent. Fabricated porous cordierite honeycomb was prepared with high porosity (58%), and good compressive strength (69MPa).

• Advances in nano research
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• 제8권2호
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• pp.157-167
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• 2020

This paper studies forced vibrational behavior of porous nanocrystalline silicon nanoshells under radial dynamic loads using strain gradient theory (SGT). This type of material contains many pores inside it and also there are nano-size grains which define the material character. The formulation for nanocrystalline nanoshell is provided by first order shell theory and a numerical approach is used in order to solve nanoshell equations. SGT gives a scale factor related to stiffness hardening provided by nano-grains. For more accurate description of size effects due to nano-grains or nano-pore, their surface energy influences have been introduced. Surface energy of inclusion exhibit extraordinary influence on dynamic response of the nanoshell. Also, dynamic response of the nanoshell is affected by the scale of nano-grain and nano-pore.