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  • Title/Summary/Keyword: SOIL CHARACTERISTICS

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Study of Soil Characteristics on Productivity of Flue-cured Tobacco (Nicotiana tabacum L.) II. Infiuences of Soil Chemical Characteristics on Productivity of Flue-cured Tobacco (황색종 담배의 생산성에 관여하는 토양특성 제2보. 토양의 화학적 특성이 황색종 담배의 생산성에 미치는 영향)

  • Kim, Yong-Yeon;Lee, Jung-Ho;Lee, Yun-Hwan
    • Journal of the Korean Society of Tobacco Science
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    • v.9 no.2
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    • pp.3-9
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    • 1987
  • This study was been conducted to determine chemical characteristics of soils in the major districts cultivating flue-cured tobacco plant. Also native soil productivities were measured by means of bioassay planting tobacco plant without fertilizer at 87 selected lolls through pot and field experiments. Inorganic nutrient in soils affecting the dry weight of tobacco leaves cultivated in the field were investigated. The results obtained are summarized as follows; 1. Among soil chemical characteristics, pH, NO3-N, NH4-N , P2O5, and Mg Influenced significantly the dry weight of tobacco loaves In pot experiment, whole In the field experiments, pH, NO3-N, NO3-N+NH4-N, and Ca had influence. 2. Correlation coefficients between soil chemical characteristics and dry weight of tobacco leaves were higher in pot experiment than field. The results revealed that soil morphological characteristics might more close influence on dry weight of tobacco leaves than chemical characteristics. 3. For prediction of dry weight (Productivity) of tobacco leaves without fertilizer multiple regression analysis were introduced using troll chemical characteristics. A combination of pH, NO3-N, and Ca was very reliable for prediction of productivity as equation. y=5.02+18.07x1 +2.61x2 +5.36x3 R=0.444** Where x1 : pH, x2 : NO3-N, x3:Ca

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Unconfined Compressive Strength Characteristics of E.S.B. Mixed Soil Based on Soil Compactness and Curing Period (토양의 다짐도와 재령기간에 따른 E.S.B. 혼합토의 일축압축강도특성)

  • Oh, Sewook;Kim, Hongseok;Bang, Seongtaek
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.5
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    • pp.47-55
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    • 2019
  • This study aims to provide basic data for soil packaging differing in accordance with the strength characteristics of mixed soil, using E.S.B. (Eco Soil Binder), an eco-friendly hardening agent, based on the type of soil. The soil used in this study is weathered granite soil readily collected in and around Korea, and is classified into SW, SP and SC according to soil classification systems. The test piece for the unconfined compressive strength test has dimensions of 50 mm in diameter and 100 mm in height, with the mix ratio of E.S.B. proportional to the weight of mixed soil changed from 5% to 10%, 15%, 20%, 25%, and 30%, where compactness of 90% and 100% were applied according to each condition to analyze the unconfined compressive strength characteristics at material ages of 3, 7, and 28 days. Also, the ratio of soil packaging standard strength and unconfined compressive strength was calculated to determine the optimal E.S.B. mix ratio, whereby the field applicability of the unconfined compressive strength using the estimation equation of ACI209R was evaluated.

Soil Layer Distribution and Soil Characteristics on Dokdo (독도의 토층 분포 및 토질 특성)

  • Kyeong-Su Kim;Young-Suk Song;Eunseok Bang
    • The Journal of Engineering Geology
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    • v.33 no.3
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    • pp.475-487
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    • 2023
  • We surveyed the distribution of soil layers on Dongdo and Seodo of Dokdo and measured the physical properties of the soils. To investigate the distribution of soil layers, the soil depth was measured directly in accessible locations, and visual observations of inaccessible locations were carried out using drones and boats. Soil depths ranged from 3 to 50 cm, and most soil layers had depths of 10~20 cm. Based on these results, a map of the soil layer was drawn using 5 cm intervals for soil depth. To analyze the soil characteristics of Dokdo, soil samples were collected from 13 locations on Dongdo and 13 locations on Seodo, in consideration of various geological settings. According to the results of grain size distribution tests, sand contents were >75%, and soil from Seodo contained more gravel-sized particles than that from Dongdo. Using the unified soil classification system (USCS) and textural classification chart of the United States Department of Agriculture (USDA), most of the soil samples from Dokdo are classified as sand, and some are classified as loamy or clayey sand. In addition, well-graded loamy or clayey sands are more common in Dongdo, and poorly graded sands with gravel are more common in Seodo. These results are expected to be important for studying soil characteristics on Dokdo.

Shear strength characteristics of reinforced decomposed granite soil by uncomsolidated-undrained triaxial compression test (비압밀비배수 삼축압축시험에 의한 보강화강풍화토의 전단강도 특성)

  • Cho, Yong-Seong;Goo, Ho-Bon;Park, Inn-Joon;Kim, You-Seong
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.103-110
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    • 2006
  • When enforced earth is used for the retain wall and four walls, the most important thing would be how to maximize the land utilization. Accordingly, in case of enforced earth, we pile up the minimal height of earth(2030cm) and harden the earth using a static dynamic hardening machine. In this paper, we tried to analyze and. compare the stress transformation characteristics of reinforced weathered granite soil. with geosynthetics when repetitive load is added to the enforced earth structure and when static load is added. The purposes of the study are as follows; 1) To compare and analyze non reinforced weathered granite soil and reinforced weathered granite. soil by executing a unconsolidated-undrained triaxial compression tests. 2) To identify the strength characteristics of weathered granite soil reinforced with geotextile due to the repetitive dynamic loads through comparison of the stress due to the static load and the repetitive dynamic loads.

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Application of Analysis Models on Soil Water Retention Characteristics in Anthropogenic Soil (인위적으로 변경된 토양에서의 수분보유특성 해석 모형의 적용)

  • Hur, Seung-Oh;Jeon, Sang-Ho;Han, Kyung-Hwa;Jo, Hee-Rae;Sonn, Yeon-Kyu;Ha, Sang-Keun;Kim, Jeong-Gyu;Kim, Nam-Won
    • Korean Journal of Soil Science and Fertilizer
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    • v.43 no.6
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    • pp.823-827
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    • 2010
  • This study was conducted to assess the propriety of models for soil water characteristics estimation in anthropogenic soil through the measurement of soil water content and soil water matric potential. Soil profile was characterized with four different soil layers. Soil texture was loamy sand for the first soil layer (from soil surface to 30 cm soil depth), sand for the second (30~70 cm soil depth) and the third soil layers (70~120 cm soil depth), and sandy loam for the fourth soil layer (120 cm < soil depth). Soil water retention curve (SWRC), the relation between soil water content and soil water matric potential, took a similar trend between different layers except the layer of below 120 cm soil depth. The estimation of SWRC and air entry value was better in van Genuchten model by analytical method than in Brooks-Corey model with power function. Therefore, it could be concluded that van Genuchten model is more desirable than Brook-Corey model for estimating soil water characteristics of anthropogenic soil accumulated with saprolite.

Characteristics of Earthquake Responses of an Isolated Containment Building in Nuclear Power Plants According to Natural Frequency of Soil (지반의 고유진동수에 따른 면진 원전 격납건물의 지진응답 특성)

  • Lee, Jin Ho;Kim, Jae Kwan;Hong, Kee Jeung
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.6
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    • pp.245-255
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    • 2013
  • According to natural frequency of soil, characteristics of earthquake responses of an isolated containment building in nuclear power plants are examined. For this, earthquake response analysis of seismically isolated containment buildings in nuclear power plants is carried out by strictly considering soil-structure interactions. The structure and near-field soil are modeled by the finite element method while far-field soil by consistent transmitting boundary. The equation of motion of a soil-structure interaction system under incident seismic wave is derived. The derived equations of motion are solved to carry out earthquake analysis of a seismically isolated soil-structure system. Generally, the results of this analysis show that seismic isolation significantly reduces the responses of the soil-structure system. However, if the natural frequency of the soil is similar to that of the soil-structure system, the responses of the containment buildings in nuclear power plants rather increases due to interactions in the system.

A Study on Friction Angle of Rock-Soil Contacts for Rock Type (암종에 따른 토사와 암반 경계면의 마찰각 변화 특성에 관한 연구)

  • Lee, Su-Gon;Lim, Chang-Ho
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.5 no.3
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    • pp.9-14
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    • 2002
  • It is common that the soil layer is few meters below the earth surface and there are rock masses below the soil layer in the view of geological characteristics in Korea. The boundary between rock and soil is clearly divided. When dealing with the stability of rock masses, as in the case of rock slopes or dam foundations, the majority of the collapses is not within the soil layer, but within the soil-rock boundary. Therefore, it is important to identify the shear strength characteristics between soil-rock contacts. It has been common practice to assume that the strength of the soil or shale represents the minimum strength present. However, it has been suggested by Patton(1968) that such an assumption may not be valid and that lower shear strengths might be obtained along the soil-rock interface than for either material alone. Then, in this thesis, introduce rock and residual soil shear strength tests and the specimen preparation and testing procedures are described in detail and also the testing results are presented and discussed.

Relative Sensitivity Analysis of the Soil Water Characteristics Curve

  • Eom, Ki-Cheol
    • Korean Journal of Soil Science and Fertilizer
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    • v.48 no.6
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    • pp.712-723
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    • 2015
  • This study was conducted to develop the SWCC estimation equation using scaling technique, and to investigate relative sensitivity of the SWCC according to the soil water tension, for the four kinds of soil texture such as Sand [S], Sandy Loam [SL], Loam [L] and Clay Loam [CL]. The SWCC estimation equation of scale factor [Θsc] (Eq. 1) was developed based on the log function (Eq. 2) and exponential function (Eq. 3). Θsc=[(ΘΘr)/(ΘsΘr)] (Eq. 1) Θsc=0.196ln(H)+0.4888 (Eq. 2) Θsc=0.3804(H)(0.448) (Eq. 3) where, Θ: water content (g/g %), Θs: water content at 0.1bar, Θr: water content at 15bar, H: soil water tension (matric potential) (bar) Relative sensitivity of soil water content was decreased as increase soil water tension, those according to soil water tension were 0.952~0.620 compared to 0.1bar case. Relative sensitivity of scale factor was also decreased as increase soil water tension, those according to soil water tension were 0.890~0.577 compared to 0.2bar case.

Characteristics of Microbial Community Enzyme Activity and Substrate Availability of Damaged Soil (훼손 토양의 미생물군집 효소 활성과 기질 이용성 특성)

  • Ji Seul Kim;Gyo-Cheol Jeong;Myoung Hyeon Cho;Eun Young Lee
    • Journal of Soil and Groundwater Environment
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    • v.28 no.5
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    • pp.68-77
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    • 2023
  • The effect of soil damage on the physicochemical characteristics and activity of the soil microbial community is not well known. This study investigates this relationship by analyzing 11 soil samples collected from various points of soil damage across Gyeonggi-do. Soil damage resulted from forest fires, landslides, and development areas, with their impacts most severe on the topsoil layer (0-30 cm). Dehydrogenase and β-glucosidase activities were notably higher at locations damaged by forest fires compared to other sites. While enzyme activities in soils influenced by landslides and development areas were relatively low, sites with a pollution history exhibited elevated dehydrogenase activity, likely due to past microbial response to the pollution. Additionally, an assessment of carbon substrate usability by soil microorganisms indicated higher substrate availability in areas impacted by forest fires, contrasting with lower availability in landslide and development sites. Statistical analysis revealed a positive correlation between organic content of sand and clay and microbial activity. These findings provide valuable insights into soil damage and associated restoration research, as well as management strategies.

Prediction of Saturation Time for the Soil Slopes due to Rainfalls (지속적인 강우에 의한 토사사면의 포화시간 예측)

  • Park, Sungwon;Han, Taekon;Kim, Hongtaek;Baek, Seungcheol
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.4
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    • pp.67-74
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    • 2007
  • Many studies for slope stability studies have indicated that the infiltration of rainwater into a slope decrease the slope stability. In order to minimize damage caused by slope failure, most design codes suggest that the slope stability be analyzed by saturated condition during rainy season. However it would be excessively conservative condition that every soil slope is saturated in rainy season irrespective of rainfall intensity, soil type and slope geometry. In addition, because most soil slopes are in an unsaturated state, it is necessary to consider the unsaturated characteristics of slope. This paper suggests a prediction method of saturation time for the weathered granite soil slopes due to rainfalls. The finite element analysis of transient water flow through unsaturated slope was used to investigate effects of soil-water characteristics, permeability at saturation, slope geometry, and rainfall intensity. From the result of these analyses, the prediction charts considering soil-water characteristics, permeability at saturation, and slope height were proposed in this study. It is possible to the time required to be saturated slope after rainfall.

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