• 한국분말재료학회지
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• 제22권2호
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• pp.122-128
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• 2015

In this study, titanium(Ti) meshes and porous bodies are employed to synthesize carbon nanotubes(CNTs) using methane($CH_4$) gas and camphene solution, respectively, by chemical vapor deposition. Camphene is impregnated into Ti porous bodies prior to heating in a furnace. Various microscopic and spectroscopic techniques are utilized to analyze CNTs. It is found that CNTs are more densely and homogeneously populated on the camphene impregnated Ti-porous bodies as compared to CNTs synthesized with methane on Ti-porous bodies. It is elucidated that, when synthesized with methane, few CNTs are formed inside of Ti porous bodies due to methane supply limited by internal structures of Ti porous bodies. Ti-meshes and porous bodies are found to be multi-walled with high degree of structural disorders. These CNTs are expected to be utilized as catalyst supports in catalytic filters and purification systems.

• 한국해양공학회지
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• 제19권4호
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• pp.9-14
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• 2005

In the present paper, the wave absorbing performance of the fully submerged horizontal porous plates has been investigated, numerically and experimentally. The submerged porous system is composed of multi-layered horizontal porous plates that are clamped at the vertical setwall, which are slightly inclined and placed vertically, in parallel, with spacing. The hydrodynamic interaction of incident waves with the rigid porous multi-layered plates was formulated within the context of linear wave-body interaction theory and Darcy's law. In order to validate the effectiveness of the present computing code, the numerical results were compared with the analytical and experimental results. It is found that triple horizontal porous plates with slight inclination, if properly tuned for wave energy dissipation against the standing waves in front of the vertical wall, can have high performances in reducing the reflected wave amplitudes against the incident waves over a wide range of wave frequency.

• 한국세라믹학회지
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• 제41권7호
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• pp.560-566
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• 2004

다중 압출 공정을 이용하여 알루미나 연속다공질체를 제조하기 위해 기공형성제로서 탄소 분말을 사용하였으며 세라믹 분말의 성형을 용이하게 하기 위하여 에틸렌 비닐 아세테이트 고분자를 바인더로 사용하였다. 압출 횟수, 압출비 및 재료의 부피비를 제어함으로써 균일한 기공의 크기와 기공률을 용이하게 제어하였다. 제조된 소결체는 연속기공을 가질 뿐아니라 우수한 비표면적을 가졌으며, 기존의 공정에 의해 제조된 알루미나 다공질 재료보다 우수한 곡강도 값을 보였다. 생체 친화성 평가를 위해 인간의 뼈모세포인 MG-63 세포를 이용해 In-vitro 실험을 실시한 결과 기공의 아랫면, 윗면, 내부 및 외부에 세포가 잘 생착하여 네트워크 형태로 치밀하게 잘 성장하였다. 또한 이 재료를 이용하여 3차원 다공질체로 제조한 후 생체적합성을 평가하기 위해 쥐의 피하조직에 이식한 결과 어떠한 염증 소견이나 생체 거부반응이 없었으며 섬유조직으로 잘 둘러 쌓인 다공질체 주위로 새로운 모세혈관이 활발히 생성되었다.

• 대한치과기공학회지
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• 제33권4호
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• pp.307-312
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• 2011

Purpose: The purpose of this study is a porous cube mechanical analysis for the dental implant. Methods: The porous cube with a side length of 10mm was designed for dental implant. To choose proper design, porous hexagon with a side 10mm which was drilled as a regular hexagon with diameter 0.8mm, 1.0mm, 1.2mm and a side 0.4mm, 0.5mm, 0.6mm each using Computer AUTO CAD(Autodesk, 2008). Each cube was carried out in the mechanical analysis. Results: The result of mechanical analysis was observed that the H0.8 was minimum stress 0.045068MPa, maximum stress 9.4565MPa and minimum strain $0.00389{\times}10^{-4}Mpa$, maximum strain $0.816{\times}10^{-4}Mpa$, the H1.0 minimum stress 0.001147MPa, maximum stress 9.099MPa and minimum strain $0.000099{\times}10^{-4}Mpa$, the maximum strain $0.784{\times}10^{-4}Mpa$, the H1.2 minimum stress 0.099393MPa, maximum stress 13.137MPa and minimum strain $0.0112{\times}10^{-4}Mpa$, maximum strain $1.13{\times}10^{-4}Mpa$. Conclusion: The mechanical analysis of porous hexahedron was that H1.0 is the best result. It will be applicable to the porous implants.

• 한국세라믹학회지
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• 제39권12호
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• pp.1177-1182
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• 2002

인산염 용액과의 반응으로 패각의 표면에 고 비표면적의 다공성 수산화아파타이트 층이 생성되는 거동을 정성적으로 관찰하였다. 수산화아파타이트의 생성기구는 패각 표면을 핵으로하는 용해-석출 반응으로 보이며 층의 생성은 다음의 과정에 의하였다. 1. 고상 표면 상의 고밀도 핵생성 및 성장 2. 결정의 접촉과 엉킴에 의한 미세 다공성 층의 형성 3. 층을 통한 용액의 확산과 내측으로의 층 두께의 성장

• Advances in materials Research
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• 제11권4호
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• pp.279-298
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• 2022

In this paper, the important novelty and the defining a physical phenomenon of the resent research is the development of nonlocal stress and strain parameters on the porous sandwich beam with functionally graded materials in the top and bottom face sheets.Also, various beam models including Euler-Bernoulli, Reddy and the generalized formulation of two-variable beam theories are obtained in this research. According to a nonlocal strain elasticity theory, the strain at a reference point in the body is dependent not only on the stress state at that point, but also on the stress state at all of the points throughout the body. Thus, the nonlocal stress-strain elasticity theory is defined that can be actual at micro/nano scales. It can be seen that the critical buckling load and transverse deflection of sandwich beam by considering both nonlocal stress-strain parameters is higher than the nonlocal stress parameter. On the other hands, it is noted that by considering the nonlocal stress-strain parameters simultaneously becomes the actual case.

• 한국분말재료학회지
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• 제18권4호
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• pp.365-371
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• 2011

In this study, gradient porous Al-Cu sintered body was fabricated by powder metallurgy processing. Al-Cu powder mixtures were prepared by low energy ball milling with various milling time. After ball milling for 3h, the shape of powder mixtures changed to spherical type with size of 100~500 ${\mu}m$. Subsequently, Al-Cu powder mixtures were classified (under 150, 150~300 and over 300 ${\mu}m$) and compacted (20, 50 and 100 MPa). Then, they were sintered at $600^{\circ}C$ for various holding time (10, 30, 60 and 120 min) in $N_2$ atmosphere. The sintered bodies had 32~45% of porosity. As a result, the optimum holding time was determined to be 60 min at $600^{\circ}C$ and sintered bodies with various porosity were obtained by controlling the compacting pressure.

• 한국세라믹학회지
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• 제41권2호
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• pp.176-181
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• 2004

지정폐기물인 전기로 제강 분진은 현재 대부분이 매립 등 부적절하게 처리되고 있어 지하수 오염 등의 환경파괴를 일으킬 위험이 있다. 전기로 제강 분진의 자원화를 위하여 전기로 제강 분진/점토의 조성으로 다공체를 제조하였으며, 다공체의 기공 특성 분석을 하였다. 다공체는 서로 다른 두 개의 미세구조로 형성되어있으며, 표면부위의 미세구조는 치밀하고 검은색이 아니고, 내부부위는 검은색이며 다공성의 미세구조(black coring)를 갖는다. 블랙코아 부위의 면적과 경량화정도를 정량화하기 위하여 Ic(core index)와 Is(shell index)를 정의하였으며, 인공경량골재로서의 최적 경량화 조건은 Ic가 0.5이상이고, Is는 0.4이상이다.

• 한국주조공학회지
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• 제23권5호
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• pp.244-250
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• 2003

The aim of this study is fabricating of composite filler metal (CFM) by a combination of selective laser sintering (SLS) of stainless steel powders (RapidSteel $2.0^{TM}$ and liquid phase infiltration of Ag-28 wt.%Cu alloy. Porous stainless steel body with inter-connected pore channels was fabricated by SLS, binder decomposing and densification processes. By the direct contact infiltration, the narrow inter-particle channels of the porous body were completely filled with the Ag-28 wt.%Cu alloy infiltrant. During infiltration, the dissolved elements of Fe, Ni and Cr from the porous body were solved into copper solid solution phases, which consist of eutectic structure of composite metal matrix. The S10C/CFM/S10C joints, which have narrow clearance gaps between them up to 10 micrometers, were joined successfully by self-feeding of filler metal from the matrix of CFM. The CFM kept its original thickness and microstructure after brazing. The tensile strength of brazed specimen was higher than 30 kgf/$mm^2$ and showed a typical ductile fracture mode in the CFM.

• 한국재료학회지
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• 제25권5호
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• pp.258-263
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• 2015

To fabricate porous SiC-Si composites for heating element applications, both SiC powders and Si powders were mixed and sintered together. The properties of the sintered SiC-Si body were investigated as a function of SiC particle size and/or Si particle contents from 10 wt% to 40 wt%, respectively. Porous SiC-Si composites were fabricated by Si bonded reaction at a sintering temperature of $1650^{\circ}C$ for 80 min. The microstructure and phase analysis of SiC-Si composites that depend on Si particle contents were characterized using scanning electron microscope and X-ray diffraction. The electrical resistivity of SiC-Si composites was also evaluated using a 4-point probe resistivity method. The electrical resistivity of the sintered SiC-Si body sharply decreased as the amount of Si addition increased. We found that the electrical resistivity of porous SiC-Si composites is closely related to the amount of Si added and at least 20 wt% Si are needed in order to apply the SiCSi composites to the heating element.