• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.123-131
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• 1994

Experimental studies were conducted to make clear the soil moisture environment under the condition of paddy-upland rotational fields by investigating water-table depths and soil moisture contents during growing season of crops in two kinds of soil. The following results were obtained. 1.Although water-table depths fluctuated with the amount of rainfall in the experimental field, it seemed that the variation of vater4able depths in the paddy-upland rotational, field was strongly affected by the condition of locations on paddy fields. 2.It is recognized that the concept of sum of excess water depth(SEWxx) and sum of excess water day(SEDxx) can be used to represent the soil moisture stress index due to the fluctuation of water-table depths. 3.The results of this study clearly indicate that drainage in paddy-upland rotational field to maintain an optimum soil moisture content must be made by introducing the concept of block drainage which needs both subsurface drainage and intercept drainage around a field. 4.Soil moisture contents were affected by both the amount of rainfall and water-table depths, however, the moisture content for top soil showed higher correlation with the amount of rainfall while that for subsoil with water-table depths.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.522-527
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• 2015

Decision of available soil depth based on soil physical and hydraulic properties for the $3^{rd}$ Landscape Vegetation Project in the Incheon International Airport was attempted. The soil samples were collected from the 8 sites at different depths, 0-20 and 20-60cm, for the three project fields, A, B, and C area. Physical and chemical properties including particle size distribution, organic matter content and electrical conductivity were analyzed. Hydrological properties including bulk density and water holding capacity at different water potential, -6 kPa, -10 kPa, -33 kPa, and -1500 kPa were calculated by SPAW model of Saxton and Rawls (2006), and air entry value was calculated by Campbell model (1985). Based on physical and hydrological limitation, feasibility and design criteria of soil depth for vegetation and landfill were recommended. Since the soil salinity of the soil in area A area was $19.18dS\;m^{-1}$ in top soil and $22.27dS\;m^{-1}$ in deep soil, respectively, landscape vegetation without amendment would not be possible on this area. Available soil depth required for vegetation was 2.51 m that would secure root zone water holding capacity, capillary fringe, and porosity. Available soil depth required for landscape vegetation of the B area soil was 1.51 m including capillary fringe 0.14 m and available depth for 10% porosity 1.35 m. The soils in this area were feasible for landscape vegetation. The soil in area C was feasible for bottom fill purpose only due to low water holding capacity.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.2
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• pp.79-84
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• 1977

In order to confirm the effect of potash top dressing and to observe the effect of N, K compound fertilizers, 17-0-17, 17-0-14, and 15-0-20, specially prepared for top dressing to rice, a field experiment with rice (Oryza Sativa L., Akibare) was conducted in a poorly drained paddy field in comparison with potassium chloride. The results obtained are as follows, 1. The effect of potash top dressing to rice was so remarkable that the yield from the plots of split application of muliate potassium or compound fertilizer was significantly higher than that from the plot received no potash at all. In contrast, the plots received all the amount of potash as one dose at transplanting time showed no significant increase in yield compared with that of potash plot. 2, The effect of N, K compound fertilizer, granulated to about the size of a small bean appeared to be so slow that it gave little increase of yield when it was appiled as a top dressing at the primodial stage, but it gave an increase of yield when it was top dressed at effective tillering stage. 3, Granular N, K compound fertilizer to be top dressed at primodial stage might be prepared in small size so that the fertilizer readily go into solution when it was applied, otherwise the fertilizer should be applied eariler than the primodial stage.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.39-48
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• 2012

The behaviors of a diaphragm wall and a contiguous pile wall such as CIP(Case-in-place pile) and SCW(Soil-cement wall), applied to the top-down construction method, were analyzed using the SUNEX program, which is widely used to design earth retaining walls. Four types of earth pressures, as described by Rankine (1857), Terzaghi and Peck (1967), Tchbotarioff (1973), and Hong and Yun (1995a), were applied to the analysis program to predict the lateral displacement of walls. The results show that the displacements of an earth retaining walls vary with the applied earth pressure. The predicted lateral displacement based on Hong & Yun's (1995a) earth pressure is similar to the measured displacement. Therefore, the actual lateral displacement of an earth retaining wall, as applied to top-down construction method, can be accurately predicted by using an analysis program considering Hong and Yun's (1995a) earth pressure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1796-1801
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• 2007

This paper presents electric potential rise on the surface of the earth due to ground currents. It is the aim of this paper to propose fundamental data relevant to the earth surface potentials depending on the soil structures. The earth potential rise, touch and step voltages in the immediate vicinity of the ground rod of a distribution pole were measured and analyzed. The results described in this paper are based on laboratory measurements which were intended to simulate conditions existing in actual installations. As a result, the earth surface potential rise, touch and step voltages strongly depend on the soil structure. The highest earth surface potential occurred in the vicinity of the top of ground rod. When the ground rod was installed in the distance range of $1{\sim}1.5\;m$ from distribution pole, the highest touch voltages appeared near the place of 1 m on the straight line connecting the distribution pole to ground rod.

• Current Research on Agriculture and Life Sciences
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• v.9
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• pp.109-114
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• 1991

The depth and spread of root systems and the density of root branching affect the success and survival of plants subjected to drought. The type and size of root systems are controlled by heredity and soil conditions. There are also important interaction between roots and shoots; roots are dependent on shoots for carbohydrates, growth regulators, and certain vitamins, and shoots are dependent on roots for water, minerals, and certain growth regulators. Pinus thunbergii Parlatore had most of roots in the top 20cm of soil, and had little short of roots in the less than 80cm of soil. Average of root density was $270cm/cm^3$ in the upper soil(0~20cm). Root density of Pinus thunbergii Parlatore was similar to that of Cryptomeria japonica. There is no saying that Pinus thunbergii Parlatore has an advantage over Cryptomeria japonica in the drought. This data will be used to the root density values in the simulation model of black pine stands.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.753-760
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• 2006

This paper presents the procedure and results of the numerical modelling that was carried out to investigate the stability of reinforced soil slopes under dynamic railway load. The two-dimensional explicit dynamic finite element method (ABACUS) was used to carry out the numerical analyses. To simulate the railway load, the top surface of the embankment was excited by the uniform distributed load whose frequency and magnitude was estimated by the measured railway acceleration during train passing. The embankment displacements and geogrid axial forces were analyzed to evaluate the stability of reinforced soil slopes under the dynamic train load.

• Mycobiology
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• v.36 no.1
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• pp.1-9
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• 2008

Sixty three species and 5 varieties belonging to 30 fungal genera were collected from 75 soil samples. Cultivated (29 genera and 58 species + 5 var.), desert (22 and 35 + 2 var.) and saline soil (21 and 41 + 1 var.) fungi were recovered on glucose-, cellulose- and 50% sucrose-Czapek's agar at $28^{\circ}C$. The most common genera were Alternaria, Aspergillus, Emerieella, Fusarium, Mycosphaerella, Nectria and Penicillium. The most prevalent species from the three types of soils on the three types of media were Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Emerieella nidulans, Fusarium oxysporum, Myeosphaerella tassiana, Nectria haematococca and Penicillium ehrysogenum. Chaetomium globosum was in the top of fungi in producing endo-$\beta$-1,4-glucanases among the 42 tested isolates obtained from soils on cellulose-Czapek's agar. Maximum production of this enzyme by C. globosum obtained after 6 days of incubation at $30^{\circ}C$ with culture medium containing maltose as a carbon source and ammonium nitrate as a nitrogen source and pH initially adjusted to 6.

• Computers and Concrete
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• v.6 no.1
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• pp.79-93
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• 2009

In the present paper, a methodology has been presented for the reliability assessment of concrete barriers that lie at a certain depth in the soil, and a missile (a rigid projectile) impacts the top of the soil cover normally, and subsequently after penetrating the soil cover completely it hits the barrier with certain striking velocity. For this purpose, using expressions available in the literature, striking velocity of missile at any depth of soil has been derived and then expressions for the depths of penetration in crater and tunnel region of concrete barrier have been deduced. These depths of penetration have been employed for the derivation of limit state functions. Using the derived limit state functions reliability assessment of underground concrete barrier has then been carried out through First Order Reliability Method (FORM). To study the influence of various random variables on barrier reliability, sensitivity analysis has also been carried out. In addition, a number of parametric studies is conducted to obtain the results of practical interest.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.142-143
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• 2021

The general ground conditions in Korea are distributed in order of fill, deposit soil, weathered soil, weathered rock, soft rock. The fill soil and deposit soil located at the top have relatively low strength compared to the lower layer, and they are sometimes classified as soft ground according to the standard penetration test results. In this study, the PF method, a ground improvement method, was applied to the soft layer, a large plate load test was conducted on the improved ground, and the results were reviewed.