• Title/Summary/Keyword: Coarse-to-Fine

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Effect if Grain Size on Plasticity of Ti$_3$SiC$_2$ (Ti$_3$SiC$_2$의 소성 변형 특성에 미치는 결정립 크기의 효과)

  • 이승건
    • Journal of the Korean Ceramic Society
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    • v.35 no.8
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    • pp.807-812
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    • 1998
  • Mechanical properties of two types of polycrystlline {{{{ { { Ti}_{3 }SiC }_{2 } }} with different grain size were investigated. A fine grain {{{{ { { Ti}_{3 }SiC }_{2 } }} has a higher fracture strength and hardness. Plot of strength versus Vickers indentation load indicated that {{{{ { { Ti}_{3 }SiC }_{2 } }} has a high flaw tolerance. Hertzian indentation test using a spherical indenter was used to study elastic and plastic behavior in {{{{ { { Ti}_{3 }SiC }_{2 } }}. Indentation stress-strain curves of each material are made to evaluate the plasticity of {{{{ { { Ti}_{3 }SiC }_{2 } }} Both find and coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} showed high plasticity. In-dentation stress-strain curve of coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} deviated even more from an ideal elastic limit in-dicating exceptional plasticity in this material. Deformation zones were formed below the contact as well as around the contact area in both materials but the size of deformation zone in coarse grain {{{{ { { Ti}_{3 }SiC }_{2 } }} was much larger than that in fine grain {{{{ { { Ti}_{3 }SiC }_{2 } }} Intragrain slip and kink would account for high plasticity. Plastic behavior of {{{{ { { Ti}_{3 }SiC }_{2 } }} was strongly influenced by grain size.

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Domestic Aggregate Quality Status and Mechanical Properties of Concrete According to Quality of Aggregate (국내 골재 품질 현황 및 골재등급에 따른 콘크리트의 역학적 특성에 관한 연구)

  • Min, Choong-Siek;Park, Jong-Ho;Jeong, Yong;Lee, Jae-Hyun;Kim, Yong-Ro;Kim, Hyo-Rak
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2012.11a
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    • pp.207-208
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    • 2012
  • This study is aimed to utilize for basic material of concrete quality management through evaluate properties of fresh and hardened concrete with the aggregate quality. As a result, fine aggregate's slump change of between one grade was 8~82% and in case of coarse aggregate, slump change of between one grade was 2~22% on same mixing condition. The unit water for same workability condition, unit water was increased 16kg/㎥ with decreasing of one grade for fine aggregate and unit water was increased 5kg/㎥ with decreasing of one grade for coarse aggregate.

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A shock analysis of foundation by NASTRAN (NASTRAN을 이용한 탑재장비 받침대의 내충격 해석)

  • Kim, Kyung-Su;Kim, Jea-Hwan;Choi, Seung-Bok;Choi, Byung-Il
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2002.05a
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    • pp.98-103
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    • 2002
  • In this paper, shock analysis was performed for coarse and fine mesh model using MSC/NASTRAN and ANSYS after substituting the foundation of deck mounted equipment of marine ship for mass-spring system. In order to determine input file in MSC/NASTRAN, dynamic response analysis was also performed using DDAM based on the calculation in the range of low frequency. It was confirmed that the coarse mesh model has the sufficient effective weight in a lower degree mode compared to fine mesh model.

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Skin Wrinkle Detection Using Dermatologic Magnifier Based on Variable Polarization and Optical Magnification (가변편광과 광학배율을 기반으로 한 피부 확대경을 이용한 피부주름 측정)

  • Bae, Young-Woo;Jung, Byung-Jo
    • Proceedings of the KIEE Conference
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    • 2006.10c
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    • pp.190-192
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    • 2006
  • The clinical characteristics of photodamaged skin, such as coarse and fine wrinkle are not accurately evaluable with previous methods. Public awareness for wrinkle treatment and prevention which rely on proper assessment and evaluation of the underlying skin changes has been increased as the population ages. In this paper, we suggest an in-vivo method and instrument that allow us to acquire a wrinkle-enhanced image to improve the accuracy of quantitative and qualitative analysis for skin wrinkle. The method used involved white LED illumination and photography through polarizing filters. Finally, the polarized light photography yields an accurate and evaluable parameter of photodamaged skin, especially fine and coarse wrinkle.

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Characterization of Length change and Free-Thaw Resistance of Recycled Aggregate Concrete (재생골재콘크리트의 길이변화 및 동결융해 저항성에 대한 실험적 특성 고찰)

  • Sim, Jong-Sung;Park, Cheol-Woo;Park, Sung-Jae;Kim, Kil-Jung;Kim, Tae-Gwang
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.109-112
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    • 2006
  • Social and environmental pressures draw greater significance on the recycling of the waste. Particularly, waste concrete is particularly crucial among the construction wastes in terms of conservation of natural construction resources as well as disposal crisis. The technology to recycle the waste concrete has been improved. This study has various replacement levels of natural fine aggregate with recycled fine aggregate while coarse aggregate is completely replaced with the recycled coarse aggregate and herein fundamental properties investigated include compressive strength, shrinkage and dynamic modulus of elasticity. As a result, it is anticipated that the recycled aggregate concrete can be successfully applied to structural concrete members provided a proper recycling process, mix design and curing method are practiced.

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A Register-Controlled Symmetrical Delay Locked Loop using Hybrid Delay Line (하이브리드 딜레이 라인을 이용한 레지스터 콘트롤 Symmetrical Delay Locked Loop)

  • 허락원;전영현
    • Proceedings of the IEEK Conference
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    • 2000.11b
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    • pp.87-90
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    • 2000
  • This paper describes a register-controlled symmetrical delay-locked-loop (DLL) using hybrid delay line for use in a high frequency double-data-rate DRAM. The proposed DLL uses a hybrid delay line which can cover two-step delays(coarse/fine delay) by one delay element. The DLL dissipate less power than a conventional dual-loop DLL which use a coarse and a fine delay element and control separately. Additionally, this DLL not only achieves small phase resolution compared to the conventional digital DLL's when it is locked but it also has a great simple delay line compared to a complex dual-loop DLL.

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Particle Size Distribution of Heavy Metals in the Urban Air of Seoul, Korea

  • Sohn, Dong-Hun;Heo, Moon-Young;Kang, Choon-Won
    • Archives of Pharmacal Research
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    • v.12 no.3
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    • pp.214-218
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    • 1989
  • Atmospheric particulate matters (A. P. M. ) were collected on quartz-fiber filters from March 1985 to May 1986, using the Andersen high-volume air sampler and contents of six heavy metals (Fe, Mn, Cu, Zn, Pb Ni) in the A. P. M. were determined by atomic absorption spectrophotometry. These heavy metals were divided into the three groups with respect to their particle size distribution. Fe and Mn were mainly associated with coarse particles (diameter > 2.0 $\mu$m), but Pb and Ni were related fine particles (diameter < 2.0 $\mu$m). Cu and Zn had mized size distributions in both of them. In the seasonal variation of heavy metals, the contents of Fe and Mn in spring and Ni and Pb in winter were higher than any other season. There were high mutual correlation between Fe and Mn coarse particles, and between Pb and Ni in fine particles.

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Surface Characteristics of Cylindrically Ground Workpiece using Laminated Grinding Wheel (적층연삭숫돌에 의한 원통연삭 가공물의 표면 특성)

  • Kim, Min-Chul;Kim, Kwang-Hee;Lee, Eun-Jong;Kim, Kang
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.3
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    • pp.35-39
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    • 2001
  • The precision grinding process is carried out with fine-cutting operation after coarse-cutting operation. So, the laminated grinding wheel has been developed to reduce the ineffectiveness induced by changing the operations. In this study, to investigate the possibility of the practical use of the laminated grinding wheel, the surface residual stress of the workpiece ground by the laminated grinding wheels was compared with that ground by the general grinding wheel, and the influence of the difference in grain sizes, between the coarse grit and fine grit of the laminated grinding wheel, on the surface roughness of the workpiece was investigated.

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Changes of Colors and Pungent Principles of Red Pepper Powder with Different Seed Contents and Particle Sizes During Storage (종자 혼입율과 입도를 달리한 고추가루의 저장 중 색과 매운맛 성분의 변화)

  • 이선미;황인경
    • Korean journal of food and cookery science
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    • v.14 no.5
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    • pp.584-588
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    • 1998
  • Red pepper powders with variuos seed contents (0%, 10%, 20%) and particle sizes were stored at 0$^{\circ}C$, 20$^{\circ}C$, and 30$^{\circ}C$ for 90 days, and the changes in their characteristics were monitored. The initial moisture content was about 13%, and the powders were packed in 0.1 mm-thick polypropylene (PP) bags. Moisture content of each power remained constantly, so PP bags appeared to be effective to prevent moisture transmission. All the values of L*, a* and b* were higher in fine particles than in coarse particles. Storage at 0$^{\circ}C$ did not change any color values, however, overall color values devreased apparently when stored at 30$^{\circ}C$ for 90 days. Capsanthin contents decreased gradually at all storage temperatures and more rapidly at higher temperature. The contents of capsaicinoids in fine particles (49∼59 mg%) were twic as much as those in coarse particles (15∼36 mg%), and they did not change throughout the storage.

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Effects of Particle Size of Alumina on Densification Behaviors of Alumina-Talc System During Liquid-Phase Sintering (알루미나-활석계의 액상소결에서 알루미나 입자크기가 치밀화 거동에 미치는 영향)

  • 김호양;이정아;김정주
    • Journal of the Korean Ceramic Society
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    • v.35 no.12
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    • pp.1308-1315
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    • 1998
  • Effects of particle size of alumina on densification behavior during liquid-phase sintering of alumina-talc system were investigated with emphasis on particle rearrangement process. In the case of using coarse alu-mina powder densiication of specimens was rapidly accelerated after formation of liquid phase due to easy particle rearrangement process with addition of talc and increase of sintering temperature. On the contrary when fine alumina powder was used premature densification of alumina matrix region formed before for-mation of liquid phase rigid skeleton structure and then it seemed to inhibit rearrangement process during crease of sintering temperature. As results the densification of specimens using coarse alumina powder was higher than that of the case of using fine one.

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