• Title/Summary/Keyword: electron microscope analysis

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Aging Characteristics of Glass Fabric/Phenolic Composites for Tilting Train Using Accelerated Aging Tester (가속노화시험장치를 적용한 틸팅열차용 유리섬유직물/페놀릭 복합재의 노화특성 평가)

  • Yoon Sung-Ho;Nam Jung-Pyo;Hwang Young-Eun;Lee Sang-Jin;Shin Kwang-Bok
    • Journal of the Korean Society for Railway
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    • v.8 no.2
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    • pp.188-194
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    • 2005
  • Aging characteristics of glass fabric/phenolic composites for tilting train subjected to combined environmental aging factors were investigated. A 2.5KW accelerated aging tester with a xenon-arc lamp was used to provide environmental aging factors such as temperature, moisture, and ultraviolet. A series of aging tests were conducted up to 3000 hours and several types of specimens were prepared along the warp direction and the fill direction. Mechanical degradations for tensile, flexural, and shear properties were evaluated as a function of exposure times through a material testing system. Thermal analysis properties such as storage shear modulus, loss shear modulus, and tan 3 were measured through a dynamic mechanical analyzer. Finally exposed surfaces of the composites were examined using a scanning electron microscope. According to the experimental results, mechanical properties and thermal analysis properties of glass fabric/phenolic composites were found to be slightly degraded as a function of exposure times due to combined environmental effects.

Microstructure Properties of High Strength Concrete Utilizing EVA with Micro Particles (EVA 마이크로 입자를 활용한 고강도 콘크리트의 미세구조특성)

  • Kim, Young-Ik;Sung, Chan-Yong
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2005.10a
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    • pp.97-101
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    • 2005
  • High strength concretes utilizing EVA with micro particles were prepared by varying polymer/binder mass ratio and curing conditions with a constant water/binder mass ratio of 0.3. The EVA modified concretes on the compressive and flexural strength, microstructure, ultrapulse modulus in curing condition(dry and water curing) were studied. Also, scanning electron microscope analysis(SEM) was performed to reveal the presence of polymer film and cement hydrates in the concrete. The compressive strength of the EVA modified concretes cured at water conditions ere higher than that of the EVA modified concretes cured at dry conditions. But, the flexural strength of the specimens cured at dry conditions were higher than that of the specimens cured at water conditions. Due to the interaction of the cement hydrates and polymer film, an interpenetrating network originated in which the aggregates were embedded. The curing of the polymer modified concrete involves two step of cement hydrates and polymer modification, and cement hydrates was promoted in water conditions and polymer film formation take place when water evaporates and was thereby was favored in dry conditions. By SEM analysis, influences of polymer modification was strengthening of the transition zone between the aggregate and the paste, and the porosity of transition zone decreases. By spring analysis, it could known that polymer film affects in porosity decrease and strengthening of transition zone.

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Studies on Transparently Crystallized Glass -On Li2O-Al2O3-SiO2 Composition- (투명 결정화 유리에 관한 연구 -Li2O-Al2O3-SiO2계 조성에 관하여-)

  • 박용완;김건은;연석주;조중희
    • Journal of the Korean Ceramic Society
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    • v.26 no.3
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    • pp.315-322
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    • 1989
  • Li2O-Al2O3-SiO2 system glasses contained P2O5, TiO2 and ZrO2as the nucleating agents were melted and formed. The glass was subsequently heated first to nucleate and then to grow the crystals. At constant nucleating agent content the base glass compositions were varied and the influences of these variations on the crystallization behaviour were investigated. The study was made by measurement of thermal expansion coefficient, differential thermal analysis, X-ray diffraction analysis, scanning electron microscope observation and transmission measurement of crystallized glass specimen in visible region. It was shown that the content of crystalline phase decreased with increasing SiO2 content as well as decresing Li2O in the base glass compositions. As the result of X-ray diffrection analysis, the major crystal was $\beta$-quartz solid solution. The degree of crystallinity which was calculated using the noncrystalline scattering methods increased in S-shape with increasing heat treatment time. This change was similar to that in thermal expansion coefficient. The transmissions of 5mm thick samples were 80-90% in visible ray region.

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Characterizing Barium Titanate Piezoelectric Material Using the Finite Element Method

  • Butt, Zubair;Rahman, Shafiq Ur;Pasha, Riffat Asim;Mehmood, Shahid;Abbas, Saqlain;Elahi, Hassan
    • Transactions on Electrical and Electronic Materials
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    • v.18 no.3
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    • pp.163-168
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    • 2017
  • The aim of the current research was to develop and present an effective methodology for simulating and analyzing the electrical and structural properties of piezoelectric material. The finite element method has been used to make precise numerical models when dielectric, piezoelectric and mechanical properties are known. The static and dynamic responses of circular ring-shaped barium titanate piezoelectric material have been investigated using the commercially available finite element software ABAQUS/CAE. To gain insight into the crystal morphology and to evaluate the purity of the material, a microscopic study was conducted using a scanning electron microscope and energy dispersive x-ray analysis. It is found that the maximum electrical potential of 6.43 V is obtained at a resonance frequency of 35 Hz by increasing the vibrating load. The results were then compared with the experimentally predicted data and the results agreed with each other.

Morphology and Molecular Data for Antarctic Cryophilic Microalga, Porosira pseudodenticulata (남극 호냉성 미세조 Porosira pseudodenticulata의 형태와 분자적 자료)

  • Jung, Woong-Sic;Joo, Hyoung-Min;Hong, Sung-Soo;Kang, Jae-Shin;Choi, Han-Gu;Kang, Sung-Ho
    • ALGAE
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    • v.21 no.2
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    • pp.169-174
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    • 2006
  • We have cultured more than 100 Arctic and Antarctic cryophilic microalgal strains in KOPRI culture collections of polar microorganisms (KCCPM). Among them, we tried to identify an Antarctic strain, KOPRI AnM0008 by morphological and molecular analysis. Nuclear SSU rDNA and plastid rbcL sequences were used to identify the strain. It was identified as Porosira pseudodenticulata based on SSU sequence data showing 99% identity with GenBank X85398. This result was supported by morphological features like solitary labiate process, external foramina and internal cribra by optical and scanning electron microscope. Morphological identification and molecular analysis on polar cryophilic microalgae will be accomplished to construct the databases for KCCPM.

Preparation and Thermal-property Analysis of Heat Storage Concrete with SSPCM for Energy Saving in Buildings (축열 성능 향상 SSPCM 혼합 콘크리트 제조 및 열적특성 분석)

  • Jeong, Su-Gwang;Chang, Seong Jin;Lim, Jae-Han;Kim, Hee-Sun;Ryu, Seong-Ryong;Kim, Sumin
    • Journal of the Korean Solar Energy Society
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    • v.35 no.1
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    • pp.89-96
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    • 2015
  • n-octadecnae based shape stabilized phase change material (SSPCM) was prepared by using vacuum impregnation method. And an exfoliated graphite nanoplate (xGnP) which has high thermal conductivity properties is used as a PCM container. And then we made heat storage concretes which contains SSPCM for reducing heating and cooling load in buildings. In the prepararion process, the SSPCM was mixed to a concrete as 10, 20 and 30wt% of cement weight. The thermal properties and chemical properties of heat storage concrete were analyzed from Scanning electron microscope (SEM), Fourier transformation infrared spectrophotometer (FT-IR), Deferential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and TCi thermal conductivity analyzer. And we conducted surface temperature analysis of SSPCM and xGnP by using heat plate and insulation mold.

Correlation study on microstructure and mechanical properties of rice husk ash-Sodium aluminate geopolymer pastes

  • Singh, N. Shyamananda;Thokchom, Suresh;Debbarma, Rama
    • Advances in concrete construction
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    • v.11 no.1
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    • pp.73-80
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    • 2021
  • Rice Husk Ash (RHA) geopolymer paste activated by sodium aluminate were characterized by X-ray diffractogram (XRD), scanning electron microscope (SEM), energy dispersion X-Ray analysis (EDAX)and fourier transform infrared spectroscopy (FTIR). Five series of RHA geopolymer specimens were prepared by varying the Si/Al ratio as 1.5, 2.0, 2.5, 3.0 and 3.5. The paper focuses on the correlation of microstructure with hardened state parameters like bulk density, apparent porosity, sorptivity, water absorption and compressive strength. XRD analysis peaks indicates quartz, cristobalite and gibbsite for raw RHA and new peaks corresponding to Zeolite A in geopolymer specimens. In general, SEM micrographs show interconnected pores and loosely packed geopolymer matrix except for specimens made with Si/Al of 2.0 which exhibited comparatively better matrix. Incorporation of Al from sodium aluminate were confirmed with the stretching and bending vibration of Si-O-Si and O-Si-O observations from the FTIR analysis of geopolymer specimen. The dense microstructure of SA2.0 correlate into better performance in terms of 28 days maximum compressive strength of 16.96 MPa and minimum for porosity, absorption and sorptivity among the specimens. However, due to the higher water demand to make the paste workable, the value of porosity, absorption and sorptivity were reportedly higher as compared with other geopolymer systems. Correlation regression equations were proposed to validate the interrelation between physical parameters and mechanical strength. RHA geopolymer shows comparatively lower compressive strength as compared to Fly ash geopolymer.

An automated determination method of particulate matter on food surface (식품표면에 부착된 미세먼지의 정량법)

  • Park, Sun-Young;Bang, Bong-Jun;Lim, Dayoung;Chung, Donghwa;Lee, Dong-Un
    • Food Science and Industry
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    • v.54 no.1
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    • pp.29-33
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    • 2021
  • Particulate matter (PM) is an air pollutant that causes serious environmental problems in Korea and other countries. The annual average PM10 concentration in Korea is around 40 ㎛/㎥, which is more than twice as high as the WHO recommended standard. When consumed with food, fine PM can pose a risk to humans. However, the risk of fine PM has been focused on the risk of fine PM introduced through the respiratory system. We investigated the quantitative measuring methods of PM10 on food surface to identify possible risk analysis of fine PM. The surfaces of food with artificially contaminated PM10 were observed with a scanning electron microscope(SEM). An automatic object-based image analysis was used to analyze the amount and size distribution of particulate matter contained in SEM micrographs.

Osseointegration of the titanium implant coated with rhTGF-${\beta}2$/PLGA particles by electrospray: a preliminary microCT analyzing rabbit study (rhTGF-${\beta}2$/PLGA 복합체를 electrospray법으로 코팅한 타이타늄 임플란트 골 유착의 microCT 계측: a preliminary rabbit study)

  • Lee, Woo-Sung;Kim, Seong-Kyun;Heo, Seong-Joo;Koak, Jai-Young;Lee, Joo-Hee;Park, Ji-Man;Park, Yoon-Kyung
    • The Journal of Korean Academy of Prosthodontics
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    • v.52 no.4
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    • pp.298-304
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    • 2014
  • Purpose: This preliminary rabbit study was conducted to evaluate the effect of recombinant human transforming growth factor-${\beta}2$ (rhTGF-${\beta}2$)/poly lactic-co-glycolic acid (PLGA) coating on osseointegration of the titanium (Ti) implant. Materials and methods: Eight Ti implants were anodized with 300 voltages for three minutes. Four of those were coated with rhTGF-${\beta}2$/PLGA by an electrospray method as the experimental group. The implants were placed into tibiae of four New Zealand rabbits, two implants per a tibia, one implant per each group. After 3 and 6 weeks, every two rabbits were sacrificed and micro-computed tomography (microCT) was taken for histomorphometric analysis. Results: In scanning electron microscope (SEM) image, the surface of rhTGF-${\beta}2$/PLGA coated Ti implant showed well distributed particles. Although statistically insignificant, microCT analysis showed that experimental group has higher bone volume / total volume (BV/TV) and trabecular thickness (Tb.Th) values relatively. Cross sectional view also showed more newly formed bone in the experimental group. Conclusion: In the limitation of this study, rhTGF-${\beta}2$/PLGA particles coating on the Ti implant show the possibility of more favorable quantity of newly formed bone after implant installation.

Analysis of CO2 Capture Efficiency in Relation to the Inlet Moisture Content of the Regenerator in the Continuous Process by using Sorbent Analysis (연속공정에서 고체흡수제의 입자분석을 통한 재생반응기 주입 수분량에 따른 CO2 회수효율 영향 분석)

  • Lee, Do-Young;Kim, Ki-Chan;Park, Young Cheol;Han, Moon-Hee;Yi, Chang-Keun
    • Korean Chemical Engineering Research
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    • v.50 no.4
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    • pp.654-658
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    • 2012
  • In this study, $CO_2$ capture efficiency in relation to the inlet moisture content of the regenerator was investigated using potassium-based sorbents in the continuous process composed of two bubbling fluidized-bed reactors, where solid outlet configuration in the regenerator was converted from underflow to overflow. XRD (X-ray Diffraction), SEM (Scanning Electron Microscope) and TGA were performed to find out the effect of water pre-treatment according to inlet moisture content in the regenerator. The $K_2CO_3{\cdot}1.5H_2O$ structure of solid sorbents has been increased as inlet moisture content of the regenerator increased. As a result, the $CO_2$ capture efficiency increased as the $K_2CO_3{\cdot}1.5H_2O$ structure of solid sorbents increased since the reactivity of the sorbents has been improved by that structure generated by the water pre-treatment. And $CO_2$ capture efficiency increased about 3~8% after sorbent outlet configuration of the regenerator was changed underflow to overflow.