• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.263-265
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• 2009

In this study, ultrafine grained (UFG) oxygen free high conductivity copper (OFHC Cu) having two different grain morphologies, one the severely elongated and the other the equiaxed, was prepared by equal channel angular pressing (ECAP) with routes A and $B_c$, respectively. The results of quasi-static tensile tests at $10^{-1}\;s^{-1}$ and $1\;s^{-1}$ and dynamic compression tests at $10^3\;s^{-1}$ order revealed that the equiaxed UFG Cu exhibited higher strength and less ductility compared to the elongated one. The difference of the plastic flow characteristics between the two were rationalized by considering their dislocation mean free length based on the orientation relationship between the possible slip planes and the loading direction.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.139-141
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• 2007

Compression tests were carried out to investigate morphologies of compressed specimen, deformation microstructure and stress-strain relation in high-nitrogen austenite stainless steel. Tests were performed under a wide range of temperature and, with true strain rates up to $\dot{\varepsilon}$ =0.05, 0.1, 0.5 and $1.0s^{-1}$. The activation energy of loading force was equal to plastic deformation energy within the temperature range of $900^{\circ}C$ to $1250^{\circ}C$. Dynamically recrystallized grain size decreased with an increasing strain rate and temperature. Flow stresses and deformation microstructures, were used to quantify the critical strain rate and recrystallized grain size. The grain size versus strain rate-temperature map obtained in the study was in good agreement with the deformation microstructures of compressed specimens.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.525-526
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• 2006

Calcium-hexaluminate phase $(CA_6)$ is known to be effective for the crack shielding due to the spinel block crystal structure. In this study, we focused to the control of $CA_6$ morphology for good damage tolerance behavior in alumina and zirconia/calcium-hexaluminate $(CA_6)$ composites. Calcium-hexaluminate $(CA_6)$ composites were prepared from zirconia, alumina and calcium carbornate powders. Calcium-hexaluminate $(CA_6)$ phase was obtained by the solid reaction through the formation of intermediate phase $(CA_2)$. $CA_6$ phase showed the column type abnormal grain grown behavior composed of small blocks. Due to the typical microstructure of $CA_6$, alumina and zirconia/calcium-hexaluminate composites provide a well controlled crack propagation behavior.

• Parasites, Hosts and Diseases
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• 제57권6호
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• pp.621-625
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• 2019

There is often the risk of confusing pollen grains with helminth eggs from archaeological sites. Thousands to millions of pollen grains can be recovered from archaeological burial sediments that represent past ritual, medication and environment. Some pollen grain types can be similar to parasite eggs. Such a confusion is represented by the diagnosis of enterobiasis in ancient Iran. The authors of this study confused a joint-pine (Ephedra spp.) pollen grain with a pinworm egg. This paper describes the specific Ephedra pollen morphology that can be confused with pinworm eggs.

• Elastomers and Composites
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• 제43권3호
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• pp.183-190
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• 2008

본 연구에서는 polypropylene 복합재료의 내스크래치성을 향상 시키기 위한 연구를 수행하였다. 내스크래치성 개선을 위하여 PP의 분자량이 다른 두 종류의 PDMS계 M/B를 제조하여 각각의 함량에 따른 기계적 물성과 내스크래치성을 평가 하였다. 더 좋은 물성을 보인 마스터배치를 선택하여 grain pattern에 따른 내스크래치성을 평가 하였다. UTM과 편광현미경을 통하여 기계적 물성과 스크래치성을 평가 하였다. Color 3D laser Scanning microscope로 표면 grain pattern 형상을 관찰하였다. 마스터배치의 분자량과 함량에 따른 기계적 물성의 차이는 비교적 적은것으로 평가 되었으며 내스크래치 평가에서는 고분자량의 M/B를 첨가함에 따라 내스크래치성이 향상 되는 것으로 나타났다. Grain pattern에 따른 스크래치 평가에서는 grain pattern이 깊이가 깊고 불규칙하며 그 형태도 크고, 둥근형일 때 내스크래치성이 우수한 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.103-106
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• 2002

The applicability of models based on fractal morphology to characterize $(Ba\;Sr)TiO_{3}$ thin film surfaces was investigated. The fractal morphology of coated barium strontium titan oxide thin film surfaces was described using fractal dimension from scanning electro microscopy image. The $(Ba\;Sr)TiO_{3}$ coating were deposited on silicon wafers using $(Ba\;Sr)TiO_{3}$ solution and spin coater. BST solution was composited by mol ratio, and then spin-coated from 3 times to 5 times coating on $Pt/SiO_{2}/Si$ substrate. Qualitative thin film analysis was performed with scanning electro microscopy (SEM), and surfaces parameters such as average grain diameter, roughness exponent and fractal dimension were determined.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.998-1000
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• 2003

We have investigated thin film morphology of pentacene thin films by the process of low-pressure gas assisted organic vapor deposition (LP-GAOVD). Source temperature, inert gas flow rate, substrate temperature and deposition pressure during film deposition is used to vary the growth rate, thin film morphology and the crystalline grain size of pentacene thin films. The electrical properties of pentacene thin films for applications in organic thin film transistor and electrophoretic displays will be discussed.

• 한국주조공학회지
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• 제14권6호
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• pp.530-540
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• 1994

Aluminium-silicon alloy(JIS AC8A) matrix composites reinforced with SiC particles were fabricated by spray-cast forming process, and the microstructure of powders and preforms produced were studied by using an optical and scanning electron microscopy. SiC particles were co-sprayed by mixed phase injection method during the spray casting process. Most of the composite powders formed by this mixed phase injection method exhibit morphology of particle-embedded type, and some exhibits the morphology of particle attached type due to additional attachment of the SiC particles on the surface of the powders in flight. The preforms deposited were resulted in dispersed type microstructure. The pre-solidified droplets and the deposited preform of SiC-reinforced aluminium alloy exhibit finer equiaxed grain size than that of unreinforced aluminium alloy. Eutectic silicons of granular type are crystallized at the corner of the aluminum grains in the preforms deposited, and some SiC particles seem to act as nucleation sites for primary/eutectic silicon during solidification. Such primary/eutectic silicons seem to retard grain growth during the continued spray casting process. It is envisaged from the microstructural observations for the deposited preform that the resultant distribution of SiC injected particles in the Al-Si microsturcture is affected by the amount of liquid phase in the top part of the preform and by the solidification rate of the preform deposited.

• 한국세라믹학회지
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• 제44권10호
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• pp.580-584
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• 2007

The ZrC layer instead of SiC layer is a critical and essential layer in TRISO coated fuel particles since it is a protective layer against diffusion of fission products and provides mechanical strength for the fuel particle. In this study, we carried out computational simulation before actual experiment. With these simulation results, Zirconium carbide (ZrC) films were chemically vapor deposited on $ZrO_2$ substrate using zirconium tetrachloride $(ZrCl_4),\;CH_4$ as a source and $H_2$ dilution gas, respectively. The change of input gas ratio was correlated with growth rate and morphology of deposited ZrC films. The growth rate of ZrC films increased as the input gas ratio decreased. The microstructure of ZrC films was changed with input gas ratio; small granular type grain structure was exhibited at the low input gas ratio. Angular type structure of increased grain size was observed at the high input gas ratio.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.194-195
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• 2005

(100-x)Zn xMg alloy films are prepared onto cold-rolled steel substrates; where x ranged from 0 to about 38 atomic %. The alloy films show microcrystalline and grain structures respectively, according to preparation conditions such as composition ratio of zinc and magnesium or gas pressures etc.. And X-ray diffraction analysis indicates not only the presence of Zn-Mg thin films with forced solid solution but also the one of $MgZn_2$ alloy films partly. In addition the influence of Mg/Zn composition ratio and morphology of the Zn-Mg alloy films on corrosion behavior is evaluated by electro-chemical anodic polarization tests in deaerated 3% NaCl solution. From this experimental results, all the prepared Zn-Mg alloy films showed obviously good corrosion resistance to compare with 99.99% Zn and 99.99% Mg Ingots for evaporation metal. It is thought that the Zn-Mg films with effective forced solid solution prepared by plasma enhanced PVD method, produces smaller and denser grain structure so that may improve the formation of homogeneous passive layer in corrosion environment.