• Title/Summary/Keyword: NAT behavior

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Undrained Cyclic Shear Behavior for Nak-Dong River Sand Due to Silt contents (실트 함유율에 따른 낙동강 모래의 반복전단거동)

  • Kim, Young-Su;Kim, Dae-Man;Shin, Ji-Seop;Na, Yun-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.311-317
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    • 2008
  • This study was carried out to improve our understanding about the influence of silt content on the stress-strain of sand under cyclic loading. Soil specimens were prepared by wet-tamping method as same void ratio and specimen's silt contents on total weights was changed from 0% to 20%. Also, effects of the silt contents on the stress-strain response were studied at different anisotropic consolidation ratio, Kc=1.0, 1.5, 2.0 condition. As a result, cyclic shear strength decreased as silt contents increased in same stress ratios. In same silt contents, cyclic shear strength increased as Kc increased in lower silt contents, but in higher silt contents, it had reverse results.

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Evaluation on Light Scattering Behavior of a Pulverized Coal Suspension (슬러리내 석탄입자의 광산란 특성 평가)

  • Hwang, Munkyeong;Nam, Hyunsoo;Kim, Kyubo;Song, Juhun
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.5
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    • pp.451-460
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    • 2013
  • In a direct coal fuel cell (DCFC) system, it is essential to identify volume fraction of coal suspended in electrolyte melt in order to control its dispersion and fluidity. This requirement is compelling especially at anode channel where hot slurry is likely to flow at low velocity. In this study, light scattering techniques were employed to measure the volume fraction for a pulverized coal suspension with relatively high absorption coefficient. The particle size, scattering angle, and volume fraction were varied to evaluate their effects on the scattering behavior as well as scattering regime. The larger coal size and smaller forward scattering angle could provide a shift to more favorable scattering regime, i.e., independent scattering, where interferences of light scattering from one particle with others are suppressed.

Effect of Incident Ion Beam Energy on Microstructure and Adhesion Behavior of TiN Thin Films (TiN 박막의 미세조직 및 밀착력에 미치는 입사이온빔 에너지의 효과)

  • Baeg, C.H.;Hong, J.W.;Wey, M.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.4
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    • pp.229-234
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    • 2005
  • Effect of incident ion beam energy on microstructure and adhesion behavior of TiN thin films were studied. Without ion beam assist, TiN film showed (111) growth mode which was thought to have the lowest deformation energy. As the ion beam assist energy increased, TiN film growth mode was changed from (111) to (200) mode. On the Si(100) substrate the critical incident energy for growth mode change was 100 eV/atom, however the critical assist energy was 121 eV/atom on the STD61 substrate. Grain size of TiN films increased with the assist ion beam energy. Finally, adhesion strength of TiN films bombarded above the critical ion assist energy showed 4~5 times higher values than that with lower bombard ion energy.

Microstructure and Mechanical Properties of High Mn TWIP Steels (고 Mn계 TWIP 강의 미세조직과 기계적 성질)

  • Jung, J.K.;Lee, O.Y.;Park, Y.K.;Kim, D.E.;Jin, K.G.;Kim, S.K.;Song, K.H.
    • Korean Journal of Metals and Materials
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    • v.46 no.10
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    • pp.627-633
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    • 2008
  • The austenitic Fe-Mn alloys have received considerable attention as a possible candidate for the automotive structural materials due to their high strength and high formability with high elongation. This research investigates the effect of alloying elements on the phase transformation, deformation behavior and mechanical properties in high Mn steels for the development of a high strength high ductility steel. The mechanical stability of austenitic phases is very important for high ductility and it depends largely on the composition of carbon, manganese and aluminum. The dominant deformation mode shifts from TRIP to TWIP mode as the amount of C, Mn and Al is increased. Especially, even a small amount of Al addition facilitates significantly TWIP deformation due to the increase of stacking fault energy in Fe-Mn alloys, this leads to increase the ductility and also decrease the crack sensitivity.

Fatigue Behavior of Before-and-After Penetration of Aluminium Plate with Long Surface Crack (긴 균열을 갖는 알루미늄판재의 관통전후 피로거동)

  • Nam Ki-Woo;Lee Jong-Rark;Ahn Seok-Hwan
    • Journal of the Korean Institute of Gas
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    • v.3 no.1
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    • pp.1-7
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    • 1999
  • Fatigue behavior of before-and-after penetration was examined experimentally using surface pre-cracked specimens of aluminium alloy 5083-0. The fatigue crack shape before penetration is almost semicircular, and the measured aspect ratio is larger than the value obtained by calculation using K values proposed by Newman-Raju. It is found that the crack growth behavior on the back side after penetration is unique and can be divided into three stages. By using a crack propagation rule in case of long surface crack, the change in crack shape after penetration can be evaluated quantitatively.

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Fabrication of Mg Alloy Foam via Melting Foaming Method Using $CaCO_3$ as Blowing Agent ($CaCO_3$를 이용한 발포 마그네슘 합금의 제조)

  • Yang, Dong-Hui;Seo, Chang-Hwan;Wang, Xiao-Song;Hur, Bo-Young
    • Journal of Korea Foundry Society
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    • v.26 no.6
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    • pp.272-276
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    • 2006
  • For the first time AZ91 (MgAl9Zn1) and AM60 (MgAl6) Mg alloy foams with homogeneous pore structures were prepared successfully via melting foaming method by using $CaCO_3$ powder as blowing agent. The possible foaming mechanisms and pore structures of these Mg alloy foams were discussed and investigated. The results show that Mg alloy melt can affect $CaCO_3$ decomposition behavior and AZ91 Mg alloy is relative easy to be foamed into metal foam with high porosity and big pore size.

Clothing Behavior of Kidult Group (키덜트(Kidult)족의 의복행동)

  • Kim, Ji-Seon;Kim, Yong-Sook
    • Korean Journal of Human Ecology
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    • v.9 no.1
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    • pp.63-70
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    • 2006
  • This study is a review of the clothing behavior of kidult group that is a new minority group in 21st century. Kidult is the compound word of kid and adult and refers the persons who have become adults but with the inclination to focus on childlike culture and consumption. As the background of the appearance of the kidult group these days, the prevalence of throwback fashions, high valuation of appearance, the phenomenon to prefer light things caused by economic depression, the individualism that does not care about others and the ageless phenomenon that the consumptions are mind age oriented, may be pointed out. The most prominent cloth behavioral characters of the kidult group are that they enjoy bounding color combinations such as candy color and. that cute t-shirts, crop pants and volume skirts of girlish look are easily found. Also, they enjoy toy-like ornaments and illustrated clothes or accessories and the school uniform fashion implying nostalgia for girl-hood and lovely make-up indicate the kidult inclination.

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Analysis of Elastic Behavior of Composite Geomaterials Using Homogenization Theory (균질화법을 이용한 복합지반물질의 역학적 특성 해석)

  • Seo, Yong-Seok;Yim, Sung-Bin;Baek, Yong;Kwon, O-Il
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.752-759
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    • 2006
  • Conglomerates and core-stones are the typical composite geomaterials that are composed of a weak matrix and a strong pebble part. In general, we couldn't analyze the composite geomaterials by using emperical rock classification methods. In the study, a series of analyses of elastic behavior of composite geomaterials are carried out by using homogenization theory. 45-case models are made with considering 3 kind of factors such as gravel content, size and strength of matrix. Those are applicable to various composite geomaterials of conglomerates and core-stones. The size of analysis model is large enough to exceed REV.

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Behavior of Flexible Hose Connected to Mother Ship (모함에 연결된 탄성 호스의 거동)

  • Kim, Kun-Woo;Lee, Jae-Wook;Kim, Hyung-Ryul;Yoo, Wan-Suk;An, Deuk-Man
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.3
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    • pp.235-240
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    • 2011
  • A flexible hose attached to a mother ship experiences various motions that depend on the movement of the mother ship and that of underwater vehicle. Although the motion of the hose is a very important factor that determines how a mother ship should be steered in a real situation, it is difficult to experimentally obtain information about the hose motion. Therefore, we study the motion of the hose analytically. The ANCF(absolute nodal coordinate formulation) was used to model the hose, because this formulation can relax the Euler-Bernoulli theory and the Timoshenko beam theory and allow the deformation of the cross section. The mother ship is assumed to be a rigid body with 6 degrees of freedom. The motion of the hose is predominantly affected by the behavior of the mother ship and by the fluid flow.

Behavior of Fiber-Reinforced Smart Soft Composite Actuators According to Material Composition (섬유 강화 지능형 연성 복합재 구동기의 재료구성에 따른 거동특성 평가)

  • Han, Min-Woo;Kim, Hyung-Il;Song, Sung-Hyuk;Ahn, Sung-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.2
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    • pp.81-85
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    • 2017
  • Fiber-reinforced polymer composites, which are made by combining a continuous fiber that acts as reinforcement and a homogeneous polymeric material that acts as a host, are engineering materials with high strength and stiffness and a lightweight structure. In this study, a shape memory alloy(SMA) reinforced composite actuator is presented. This actuator is used to generate large deformations in single lightweight structures and can be used in applications requiring a high degree of adaptability to various external conditions. The proposed actuator consists of numerous individual laminas of the glass-fiber fabric that are embedded in a polymeric matrix. To characterize its deformation behavior, the composition of the actuator was changed by changing the matrix material and the number of the glass-fiber fabric layers. In addition, current of various magnitudes were applied to each actuator to study the effect of the heating of SMA wires on applying current.