• Title/Summary/Keyword: soil characteristics

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Analysis of Soil Characteristics and its Relationship According to the Geological Condition in Natural Slopes of the Landslide Area (산사태지역 자연사면의 지질별 토질특성 및 상관관계 분석)

  • Kim, Kyeong-Su
    • The Journal of Engineering Geology
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    • v.17 no.2 s.52
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    • pp.205-215
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    • 2007
  • In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas. Also, the relationship with landslides and interrelation with each soil properties are analyzed. The landslides in three areas with different geological condition are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. However soil characteristics have a little differentiation to geological condition, the soils sampled from landslide area have higher proportion of fine particle and porosity, and lower density than those from non landslide area. In case of same geological condition, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. The soil layer with high internal friction angle is more stable than that with low internal friction angle in all geological condition. The permeability is mainly influenced by effective particle size, coefficient of uniformity, coefficient of gradation, porosity, density and so on. Also, those have interrelation with each factor. These interrelations are similar in all study area. Meanwhile, in proportion as the void ratio and the porosity rises the permeability increases.

Soil Characteristics according to the Geological Condition of Soil Slopes in Landslide Area (산사태지역 토층사면의 지질조건별 토질특성)

  • Kim, Kyeong-Su
    • The Journal of Engineering Geology
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    • v.16 no.4 s.50
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    • pp.359-371
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    • 2006
  • In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas composed with gneiss, granite, and the tertiary sedimentary rock. To investigate the soil characteristics according to landslide and non landslide areas, soils are sampled from Jangheung, Sangju and Pohang. The landslides at three areas are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. On the basis of the landslide data and the result of soil test, the soil characteristics at the landslide area and the differentiation between landslide area and non landslide area are analyzed. However soil characteristics have a little differentiation to geological condition, the uniformity coefficient and the coefficient of gradation of soils at the landslide area is larger than those of soils at the non landslide area. Also, the proportion of fine particle of soils at the landslide area is higher. The plastic limit of soils sampled from the granite and the sedimentary rock regions is larger than that sampled from the gneiss region. However the liquid limit is irrelevant to the geological condition. Also, the consistency of soils at the landslide area is smaller. The natural moisture content of soils in the sedimentary rock regions is larger than that of the granite and gneiss. It is mainly influenced by mineral composition, soil layer structure, weathering condition, and so on. The soils sampled from landslide area have higher porosity and lower density than those from non landslide area. It means that the soils of landslide area have poor particle size distribution and loose density. Therefore, the terrain slope with poor distribution and loose density is vulnerable to occur in landslides. Also, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. Meanwhile, the shear strength of soils is little difference according to the geological condition. But, the internal friction angle of soils sampled from the landslide area is lower than that of soils from the non landslide area. Therefore, the terrain slope with low internal friction angle is more vulnerable to the landslide.

Prediction of Tractive Performance of Off-Road Wheeled Vehicles (로외에서 운용되는 휠형차량의 견인성능 예측)

  • 박원엽;이규승
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.188-195
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    • 2000
  • This study was conducted to develop the mathematical model and the computer simulation program(TPPMWV) for predicting the tractive performance of off-road wheeled vehicles operated on various soil conditions. The model takes into account main design parameters of a wheeled vehicle, including the radius and width of front and rear tires, the weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 5.25%(4WD) AND 9.42%(2WD)for two different driving types, respectively.

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Effects of Soil Neutralizing Treatments on Soil Characteristics and Growth of Aster koraiensis in the Acid Soil of Abandoned Metal Mine

  • Jung, Mun Ho;Lee, Sang Hwan;Kim, Yoon Su;Park, Mi Jeong
    • Korean Journal of Soil Science and Fertilizer
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    • v.49 no.3
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    • pp.287-292
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    • 2016
  • The objectives of this study were to investigate the effects of soil neutralizing treatments on soil characteristics and growth of Aster koraiensis in the acid soil of abandoned metal mine for selection of proper neutralizer. The most effective neutralizers were acid mine drainage sludge, waste lime + oyster and compost. Those neutralizing treatments showed promoting growth of Aster koraiensis. According to this study, it is applicable of acid mine drainage sludge, waste lime + oyster and compost to neutralize acid soil for rehabilitation in abandoned metal mine. However, follow-up study is necessary to calculate proper ratio of each neutralizer.

Theoretical Prediction and Experimental Substantiation of Tractive performance of Off-Road Tracked Vehicles (로외에서 운용되는 궤도형차량의 견인성능에 관한 이론적 예측과 실험적 검증)

  • 박원엽;이규승
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.6
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    • pp.248-257
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    • 1999
  • A mathematical model was developed to investigate the mechanical interrelation between soil characteristics and main design factors of a tracked vehicles , and predict the tractive performance of the tracked vehicles. Based on the mathematical model, a computer simulation program(TPPMTV98) was developed in this study. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMTV98 with measured ones from traction tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92%(d.b). The drawbar pulls measured by the TPPMTV98 were well matched to the measured ones. Such results implied that the model developed in this study could estimate the drawbar pulls well at various soil conditions , and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

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Characteristics of Plant Distribution in the Reclaimed Dredging Area in Gwangyang Bay, Korea

  • Nam, Woong;Kwak, Young-Se;Lee, Deok-Beom;Lee, Sang-Suk
    • Journal of Ecology and Environment
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    • v.32 no.2
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    • pp.115-121
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    • 2009
  • In order to elucidate the mechanisms affecting plant distributions in the reclaimed dredging area in the Gwangyang steelworks, in the Gwangyang Bay, Korea, we examined soil characteristics and plant distributions in four study sites and a control site in the study area. Desalination occurring along a gradient with increasing elevation, resulting in decrease of soil pH, EC, P, K, Cl, Ca, Mg, and salt and an increase in soil T-N, silt, clay contents. From site 1 (the lowest-elevation site) to site 5 (the highest-elevation site), halophytes decreased in abundance and nonhalophytes increased. The dominant species in each site were: Phragmites communis, Limonium tetragonum, and 12 additional species at site 1, Carex pumila, Suaeda japonica, and 15 additional species at site 2, Spergularia marina, Scirpus planiculmis, and 22 additional species at site 3, Miscantus sinensis, Lespedeza bicolor, and 26 additional species at site 4 and Pinus thunberii, Rhododendron mucronulatum, and 39 additional species at site 5, which resembled a naturally-occurring P. thinbergii community. Cluster analysis of the vegetation data matrix grouped the 35 plots into 5 major groups, and cluster analysis using the soil environment data matrix revealed 4 major groups. CCA of the floristic and environmental data matrix showed a positive relationship of SAR, EC, Na, Cl, and Ca, which are related to salt, in the $1^{st}$ axis and $2^{nd}$ axis, but negative relationships for altitude, organic contents, silt, and clay contents. Notably, plant species in the reclaimed dredging area that were separated along the $1^{st}$ axis showed strong relationships with factors that related to salt. Long-term exposure to natural rainfall in the reclaimed dredging area changed the soil characteristics, such as salinity. This change in soil characteristics might alter the SAR, which affects plant survival strategies in a given habitat. These results strongly indicated that factors related to salt and elevation play important roles in determining the overall plant distribution in the reclaimed dredging area.

Breeding Site Preferences and the Effects of Breeding Black-crowned Night Herons (Nycticorax nycticorax) on Soil Characteristics at Bamsum Island in Seoul

  • Nam, Jong-Min;Jeon, Sung-Je;Kim, Jae-Geun
    • Journal of Ecology and Environment
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    • v.30 no.4
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    • pp.341-346
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    • 2007
  • Nest density was determined and tree and soil characteristics around Nycticorax nycticorax breeding sites and non-breeding sites on Bamsum Island in Seoul were analyzed from May 2005 to October 2006 to identify breeding site preferences of N. nycticorax and the effects of N. nycticorax nesting density on nesting tree structure and soil characteristics. N. nycticorax preferred trees of low height ($3.5{\sim}6$ m) and small diameter at breast height in high density Salix communities. Excrement of heron juveniles was dropped on the soil under the nests. The soil nutrient content under nests (P: 126.0 mg/kg, N: 202.8 mg/kg, EC: 549 ${\mu}S/cm$, pH 4.7) was much higher than that of control soils from Bamsum Island not enriched by heron excrement (P: 41.5 mg/kg, N: 42.0 mg/kg, EC: 342 ${\mu}S/cm$, pH 5.1). Formation of Salix communities on the shores of Bamsum Island is ongoing, and their structure has been directly influenced by annual flooding. After flooding, the nutrient content differences between heron-affected soils and control soils were not significant. This might be the reason that Salix communities on Bamsum were not affected by nesting herons as in other terrestrial communities where herons nest. This result indicates that flooding plays an important role in sustaining Salix communities on Bamsum Island where herons nest. The results of this study may increase understanding of N. nycticorax breeding behavior which may be useful for conservation planning.

Effects of Controlled Drainage Systems on Soybean (Glycine max L.) Growth and Soil Characteristics in Paddy Fields

  • Lee, Sanghun;Jung, Ki-Yuol;Chun, Hyen Chung;Choi, Young Dae
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.62 no.2
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    • pp.134-142
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    • 2017
  • Crop production in rice paddy fields is of great importance because of declining rice consumption and the low self-sufficiency ratio for field crops in Korea. A controlled drainage system (CDS) is recognized as an effective means to adjust water table (WT) levels as needed and control soil water content to improve the soil environment for optimum crop growth. The present study evaluated the effects of a CDS on soil characteristics, including soil water distribution and soybean development in paddy fields. The CDS was installed with two drain spacing (3 m and 6 m) at the experimental paddy field at the National Institute of Crop Science, Miryang, Korea. It was managed with two WT levels (0.3 m and 0.6 m) during the growing season. Soil water content, electrical conductivity and plant available nitrogen content in the soil were significantly greater in the 0.3 m WT management plots than in the 0.6 m plot and the control. At the vegetative stage, chlorophyll content was significantly lower with higher WT control because of excess soil moisture, but it recovered after the flowering stage. Soybean yield increased with WT management and the 0.6 m WT treatment produced the greatest grain yield, $3.38ton\;ha^{-1}$, which was 50% greater than that of the control. The CDS directly influenced outflow through the drains, which significantly delayed nutrient loss. The results of this study indicated that WT management by CDS can influence soil characteristics and it is an important practice for high yielding soybean production in paddy fields, which should be considered the crop growth stages for stable crop production.

Effect of green manure barley and hairy vetch on soil characteristics and rice yield in paddy (녹비보리와 헤어리베치 토양투입에 따른 벼 수량 및 토양특성)

  • Cho, Hyeoun-Suk;Park, Woo-Young;Jeon, Weon-Tai;Seong, Ki-Yeung;Kim, Chung-Guk;Park, Tae-Seon;Kim, Jae-Deok
    • Korean Journal of Agricultural Science
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    • v.38 no.4
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    • pp.703-709
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    • 2011
  • This study was conducted at Korea's typical soil, loamy soil, to figure out the effect of how barley green manure (B), hairy vetch (HV) and the mixed-planting hairy vetch with barley green manure (HV/B) affecting on the yield of rice, usage of nutrient and soil characteristics. Supplying amount of nitrogen from HV, HV/B and B were 172.8 kg $ha^{-1}$, 64.3 kg $ha^{-1}$ and 38.6 kg $ha^{-1}$, respectively. Hairy vetch had the highest plant height and SPAD of rice and next was hairy vetch/barley, chemical fertilizer (CF), none fertilizer (NF), and green manure barley. The amount of rice yield was 5.51 ton $ha^{-1}$ with HV, and 4.24 ton $ha^{-1}$ with HV/B. The chemical characteristics of soil showed lower pH and exchangeable cations (Ca and Mg) at B, HV and HV/B plot rather than that of chemical fertilizer (CF) plot. However, the physical characteristics of soil and the porosity rate showed better tendency at the green manure crops than CF. Nitrogen nutrient balance was showed the most balanced at CF, otherwise field of application of green manure crops were required the appropriate nutrition management if future crops would be cultivated because nitrogen nutrient could be devastated or accumulated.