• Title, Summary, Keyword: Inhomogeneous

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Study on the noodle-making properties of rice added with hydroxypropyl methylcellulose (I) (히드록시프로필 메틸셀룰로오스 첨가에 의한 쌀국수 제면성 연구 (I))

  • Yoo, Young-Jin;Kang, Mi-Young;Um, In-Chul
    • Current Research on Agriculture and Life Sciences
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    • v.30 no.2
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    • pp.61-67
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    • 2012
  • In this study, hydroxypropyl methylcelluloses (HPMCs) were added to prepare the rice noodle and the effects of water dosage, HPMC content, and viscosity level of HPMC on the noodle-making properties of rice dough were examined. As the water dosage was increased, the rice dough after roller pass became more flat and homogeneous. However, when the water dosage was over a certain range, the rice noodle became more waved. In the test result of various HPMC contents, 3% HPMC addition was turned out to be an optimum condition for the best noodle-making properties of rice dough. As the viscosity level of HPMC decreased, the rice dough after roller pass became inhomogeneous. However, the lowest viscosity level HPMC (PMC 40H) did not show any waved rice noodle at even high water dosage indicating the improved noodle-making properties of rice dough. On the whole, it seems that 56~58% water dosage, 3% HPMC content, and high viscosity HPMC (PMC60U) were the optimum condition for preparation of good rice noodle.

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Omnipresence of Strain Localization in Soils (흙의 변형국지화 편재에 관한 연구)

  • 권태혁;조계춘
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.199-210
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    • 2003
  • The development of strain localization within shear zones is frequently observed during soil deformation. In fact, the phenomenon appears to be more often the norm rather than the exception. Conceptually, any soil condition that renders negative work increment is prone to localization. In this study, a broad range of soil and loading conditions are investigated to test this criterion, including: dilative soil subjected to drained shear (standard case), contractive soil sheared under undrained conditions, cavitation in dilative soil in undrained shear, inhomogeneous soils, particle alignment in contractive soils made of platy particles, soils that experience particle crushing, and the shear of low-moisture and/or lightly cemented loose soils. Unique specimens and test procedures are designed to separately test each of these soil conditions in the laboratory According to experimental test results, soil specimens with post-peak strain softening behavior are prone to progressive failure, localization of deformations, and shear banding. The state of stress, the soil density, inherent mechanical and geometrical properties of soil particles, low water content, and heterogeneity can contribute to triggering strain localization. Considering all possible cases of localization, the best method to obtain the critical state line in the laboratory is to use contractive homogeneous specimens subjected to drained shear.

A Study on Seismic Source and Propagntion Characteristics using a Series of 12 Fukuoka Earthquakes (후쿠오카 지역에서 발생한 12개 지진의 지진원 밑 지진파 감쇠값에 관한 연구)

  • Kim, Jun-Kyoung
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.1
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    • pp.89-97
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    • 2007
  • Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 12 Fukuoka region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy in fiequency domain. Average stress drop of 12 events and local attenuation parameter $\kappa$ under seismic stations were estimated to about 79.2-bar and 0.043 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 248.1 and 0.558 respectively. Low value of Qo seems to caused by inhomogeneous tectonic characteristics between Japan island and southern Korean peninsula. $\kappa$ values are much higher than that characterizing EUS (Eastern United States) region, and nearly similar to that of WUS (Western Waited States) region. If the informations on site specific amplification of all the seismic stations are known, $\kappa$ values can be estimated more precisely. All the values including the seismic sources and the site and crustal scale propagation characteristics can be used as seismic design parameters.

Effects of the Powder Preparation Method on the Magnetic Properties of Fe-based Amorphous Alloy Powder Cores (철계 비정질 합금 분말코아의 자기적 특성에 미치는 분말 제조방식의 영향)

  • Noh, T.H.;Choi, H.Y.
    • Journal of the Korean Magnetics Society
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    • v.15 no.3
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    • pp.191-197
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    • 2005
  • In the fabrication process of Fe-based amorphous alloy powder cores by pulverization of the melt-spun ribbons and cold compaction, the effects of powder preparation method on the magnetic & electric properties, powder shapes and microstructure of cores have been investigated. The powder cores made by using rotor mill showed low effective permeability as compared to the cores prepared by ball milling. However the frequency dependence and quality factor properties were superior in the case of rotor-milling. Further the powders prepared by rotor mill had homogeneous and round shapes through strong shearing in the sieve ring, while the ball milled powders were inhomogeneous and relatively small. The lower permeability of the powder cores fabricated with rotor mill was considered to be due to the high internal stress occurred by very intensive shearing. Moreover the powder cores produced by rotor-milling showed lower core loss and good frequency dependence of effective permeability possibly due to the higher electrical insulation between magnetic particles. The dc bias property of the powder cores made by rotor-milling was better than the one by ball-milling.

Selective Chemical Dealloying for Fabrication of Surface Porous Al88Cu6Si6 Eutectic Alloy (화학적 침출법을 통한 표면 다공성 Al-Cu-Si 공정 합금 제조)

  • Lee, Joonhak;Kim, Jungtae;Im, Soohyun;Park, Hyejin;Shin, Hojung;Park, Kyuhyun;Qian, M.;Kim, Kibeum
    • Korean Journal of Materials Research
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    • v.23 no.4
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    • pp.227-232
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    • 2013
  • Al-based alloys have recently attracted considerable interest as structural materials and light weight materials due to their excellent physical and mechanical properties. For the investigation of the potential of Al-based alloys, a surface porous $Al_{88}Cu_6Si_6$ eutectic alloy has been fabricated through a chemical leaching process. The formation and microstructure of the surface porous $Al_{88}Cu_6Si_6$ eutectic alloy have been investigated using X-ray diffraction and scanning electron microscopy. The $Al_{88}Cu_6Si_6$ eutectic alloy is composed of an ${\alpha}$-Al dendrite phase and a single eutectic phase of $Al_2Cu$ and ${\alpha}$-Al. We intended to remove only the ${\alpha}$-Al phase and then the $Al_2Cu$ phase would form a porous structure on the surface with open pores. Both acidic and alkaline aqueous chemical solutions were used with various concentrations to modify the influence on the microstructure and the overall chemical reaction was carried out for 24 hr. A homogeneous open porous structure on the surface was revealed via selective chemical leaching with a $H_2SO_4$ solution. Only the ${\alpha}$-Al phase was successfully leached while the morphology of the $Al_2Cu$ phase was maintained. The pore size was in a range of $1{\sim}5{\mu}m$ and the dealloying depth was nearly $3{\mu}m$. However, under an alkaline NaOH, aqueous solution, an inhomogeneous porous structure on the surface was formed with a 5 wt% NaOH solution and the morphology of the $Al_2Cu$ phase was not preserved. In addition, the sample that was leached by using a 7 wt% NaOH solution crumbled. Al extracted from the Al2Cu phase as ${\alpha}$-Al phase was dealloyed, and increasing concentration of NaOH strongly influenced the morphology of the $Al_2Cu$ phase and sample statement.

Non-Destructive Precise Electromagnetic Surveying for the Deep Underground Utilities (고심도 지중매설물의 지하측랑을 위한 비파괴 정밀 전자측량)

  • 손호웅;이강원;김형수
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.21 no.2
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    • pp.109-121
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    • 2003
  • Lots of various utilities are buried under the surface. The effective management of underground utilities is becoming the very important subject for the harmonious administration of the city. Ground Penetrating Radar(GPR) survey including other various underground survey methods, is mainly used to detect the position and depth of buried underground utilities. However, GPR is not applicable, under the circumstances of shallow depth and places, where subsurface materials are inhomogeneous and are composed of clay, salt and gravels. The aim of this study is to overcome these limitations of GPR and other underground surveys. High-frequency electromagnetic (HFEM) method is developed for the non-destructive precise deep surveying of underground utilities. The method is applied in the site where current underground surveys are useless to detect the underground big pipes, because of poor geotechlical environment. As a result, HFEM survey was very successful in detecting the buried shallow and deep underground pipes and in obtaining the geotechnical information, although other underground surveys including GPR were not applicable. Therefore this method is a promising new technique in the lots of fields, such as underground surveying and archaeology.

Viscoelastic Behavior of High Density Polyethylene Using High Tibial Osteotomy with Respect to the Strain Rate (근위경골절골술(HTO)용 X-밴드 플레이트에 적용되는 고밀도 폴리에틸렌(HDPE)의 변형률속도에 따른 점탄성거동)

  • Hwang, Jung-Hoon;Kim, Cheol-Woong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.4
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    • pp.431-438
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    • 2012
  • The mechanical behavior of the polymeric material, HDPE depends on both time and temperature. The study of the tensile behavior at different strain rates is important in engineering design of the orthopedics device such as X-band plate. The mechanical properties and deformation mechanisms of HDPE are strongly dependent on the applied strain rate. Generally, the deformation behavior of HDPE based on the stress-strain curve is complex because of the highly inhomogeneous nature of plastic deformation, particularly that of necking. Therefore, we attempted to determine the mechanical behavior of HDPE in this study. Normally, tensile testing under various strain rates of the HDPE has been used to determine the mechanical behavior. We performed tensile tests at various strain rates (1 to 500 %/min) to analyze the viscoelastic behavior on increasing the strain rate. A tensile stress-strain curve was plotted from the data, and the point of transition was marked to calculate the transition stress, strain, and modulus.

High temperature properties of surface-modified Hastelloy X alloy (표면처리에 따른 Hastelloy X 합금의 고온물성)

  • Cho, Hyun;Lee, Byeong-Woo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.4
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    • pp.183-189
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    • 2012
  • Surface treatments and their effects on high temperature properties for the Hastelloy X, which is a promising candidate alloy for high temperature heat-transport system, have been evaluated. For TiAlN and $Al_2O_3$ overlay coatings, the two different PVD (physical vapor deposition) methods using an arc discharge and a sputtering, were applied, respectively. In addition, a different surface treatment method of the diffusion coating by a pack cementation of Al (aluminiding) was also adopted in this study. To achieve enhanced thermal oxidation resistance at $1000^{\circ}C$ by suppressing the inhomogeneous formation of thick $Cr_2O_3$ crust at the surface region, a study for the surface modification methods on the morphological and structural properties of Hastelloy X substrates has been conducted. The structural and compositional properties of each sample were characterized before and after heat-treatment at $1000^{\circ}C$ under air and He environment. The results showed that the Al diffusion coating showed the more enhanced high temperature properties than the overlay coatings such as the suppressed thick $Cr_2O_3$ crust formation and lower wear loss.

Synthesis and characterization of perovskite nano-sized (Pb, La)$TiO_3$ powder using mechano chemical process (기계화학공정을 이용한 Perovskite 구조의 (Pb, La)$TiO_3$ 나노 분말 합성 및 특성)

  • Lim, Bo-Ra-Mi;Yang, Jae-Kyo;Lee, Dong-Suk;Noh, Tae-Hyung;Seo, Jung-Hye;Lee, Youn-Seoung;Kim, Hee-Taik;Choa, Yong-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.5
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    • pp.200-204
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    • 2008
  • Mechano Chemical Process (MCP) skips the calcinations steps at an intermediate temperature that is always required in the conventional solid-state reaction because forming phase from raw powder is activated by mechanical energy. In this study, we prepared (Pb, La)$TiO_3$ nanopowder with perovskite structure by only high energy MCP. Especially, the PLT nanopowder was synthesized without any thermal treatment using oxides, not salts as raw powder. This process is also very simple due to dry milling method, unnecessary to dry of powder. The oxide powder was milled up to 12 hr at intervals of an hour using MCP and the pure PLT phase of perovskite structure was formed after milling time of 3 hr. And the average particle size was 20 nm with narrow distribution after milling time of 3 hr from raw powder of several $\mu m$ with inhomogeneous distribution.

Alteration Textures and Mineral Chemistry of Margarite from Miwon Area, Chungcheongbukdo (충북미원지역에서 산출하는 마카라이트의 변질양상 및 광물화학)

  • 이승준;안중호;김현철;조문섭
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.1
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    • pp.69-77
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    • 2002
  • Margarite, which occurs in the Unkyori Formation of Miwon area, Chungcheongbukdo, South Korea, was investigated using the petrographic microscope, back-scattered electron images (BSEI), and electron probe microanalyzer (EPMA) to characterize the alteration textures and mineral chemistries. Most margarite crystals are inhomogeneous, and chlorite was commonly observed to occur at the boundaries parallel to the rim of margarite. Cracks occur across the basal plane of the margarite, and margarite is partly replaced by chlorite along the cracks. In additon, muscovite and biotite are intergrown in margarite and chlorite crystals, suggesting that margarite was partially altered to chlorite as well as to muscovite and biotite. Chemical analysis data show that paragonite solid solution in the margarite is approximately 19.6 mol%, but clintonite solid solution is negligible. Margarite crystals in the Unkyori Formation cut or penetrate other metamorphic minerals In the same thin sections and are oriented randomly without any relationship with the foliation of host rocks, indicating that formed as a secondary mineral after peak metamorphism. Furthermore, it seems that hydrothermal fluids associated with the Mesozoic intrusions developed near the sample are closely related to the margarite formation.