• Title/Summary/Keyword: furrow

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A Study on the Soil Stress Distribution in Furrow Slice (역토내(壢土內)의 응력분포(應力分布)에 관(關)한 연구(硏究))

  • Lee, Ki Myung;Lee, Suk Gun;Kim, Tae Han
    • Journal of Biosystems Engineering
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    • v.7 no.2
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    • pp.1-7
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    • 1983

  • In order to identify the stress distribution on the furrow slice a small soil bin instrumented with soil stress meters was designed and constructed. From a series of experiments conducted in the soil bin the following results were obtained. 1) Neither the cutting conditions nor the soil conditions affected the direction of the principal stress. 2) The magnitude of the principal stress increased as the tillage depth increased. However, no effects due to lift angles were shown on the magnitude of the principal stresses. 3) The maximum principal stress increased with increase of the moisture and clay contents in the soil. 4) In the clay soil, the maximum principal stresses were distributed uniformly over the tillage depth. However, as the sand content increased, the maximum principal stresses decreased gradually on the top layer so that the distribution over the tillage depth became a trapezoidal shape.

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Lockeia gigantus ichnosp. nov. in the Lacustrine Deposits of the Early Cretaceous Jinju Formation, Southern Coast of Korea (남해안 전기 백악기 진주층의 호성 퇴적층에서 산출된 Lockeia gigantus ichnosp. nov.)

  • Kim, Kyung-Soo;Kim, Jeong-Yul
    • Journal of the Korean earth science society
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    • v.29 no.1
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    • pp.13-28
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    • 2008

  • About 450 specimens of Lockeia were discovered from the lacustrine siltstone of the Early Cretaceous Jinju Formation of Jin Island, southern coast of Korea. They are very elongated, seed-shaped Lockeia characterized by a large size, mostly 60-70 mm long and 15-20 mm wide. They are characteristically sharp longitudinal furrow bounded by steeply inclined both margins, elevated marginal rims and sharp pointed both longitudinal furrow ends. This trace fossil is herein described as Lockeia gigantus ichnosp. nov. Plicatounio, a freshwater bivalve which does not occur occurs occasionally within Lockeia gigantus is regarded as the most-likely producer of this resting trace fossil. This new trace fossil represents the largest Lockeia ever known and the first record of Lockeia from the Cretaceous non-marine deposits in the world. This fossil also represents an unusual example of resting trace fossil (Lockeia) associated with a possible producer (bivalve Plicatounio) lived in community in the shallow lacustrine environment.

  • https://doi.org/10.5467/JKESS.2008.29.1.013 인용 PDF KSCI

수정난내의 세포질의 재배치가 발생에 미치는 영향: 양서류난의 역위와 난할양상의 관계

  • 정해문;김평현;김덕희
    • The Korean Journal of Zoology
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    • v.26 no.3
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    • pp.193-202
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    • 1983

  • Inversion at variable time of the uncleaved eggs of Rana nigromaculata and Rana dybowskii was emplyed to study the mechanisms of early embryogenesis. The response to inversion varied between those two spcies. If the eggs were inverted at early time it was possible to change the site of the first cleavage furrow of Rana nigromaculata-it appeared on the original vegetal hemisphere (OpG side). However, the first cleavage furrow of Rana dybowskii was not changed at all no matter what its inversin time was-it always appeared on the original animal hemisphere (G. side). In the inverted Rana nigromaculata embryos the size of the blastomeres on the vegetal hemisphere was always smaller than those of animal hemisphere. On the ocntrary, the cleavage pattern of Rana dybowskii was not altered. Results of the histological works for the inverted eggs suggest that the different responses to inversion might be caused by the fact that the extent to which the redistribution of the egg components such as cleavage nuclei and yolk platelets are different.

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