• Journal of Ecology and Environment
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• 제34권2호
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• pp.193-202
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• 2011

We studied temperature sensitivity characteristics of soil respiration during periods of rising and falling temperatures within a common temperature range. We measured soil respiration continuously through two periods (a period of falling temperature, from August 7, 2003 to October 13, 2003; and a period of rising temperature from May 2, 2004 to July 2, 2004) using an open-top chamber technique. A clear exponential relationship was observed between soil temperature and soil respiration rate during both periods. However, the effects of soil water content were not significant, because the humid monsoon climate prevented soil drought, which would otherwise have limited soil respiration. We analyzed temperature sensitivity using the $Q_{10}$ value and $R_{ref}$ (reference respiration at the average temperature for the observation period) and found that these values tended to be higher during the period of rising temperature than during the period of falling temperature. In the absence of an effect on soil water content, several other factors could explain this phenomenon. Here, we discuss the factors that control temperature sensitivity of soil respiration during periods of rising and falling temperature, such as root respiration, root growth, root exudates, and litter supply. We also discuss how the contribution of these factors may vary due to different growth states or due to the effects of the previous season, despite a similar temperature range.

• 한국조경학회지
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• 제33권6호
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• pp.40-50
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• 2006

This study was carried out to examine the tree-ring growth characteristics of Zelkova serrata Makino after replanting, for the built-up planting founds for stability of landscaped trees in the reclaimed land from the sea. the factors, many affecting the growths of Zelkova serrata Makino, were the replanting stress and drought. The growth reduction due to replanting and drought occurred in the replanting year and the following year. The mean sensitivity(year-to-year variation) and the coefficient of variation(tree-to-tree variation in a certain year) in tree rings of Zelkova serrate Makino, were higher in the poor soil sites than in the favourable soil ones. And the poor soil sites were the filled ground of improve soil and the covered ground of improve soil and the top ground of big mounding than mounding ground sites, especially soil hardness, alkali soil, high $Na^+\;and\;K^+,\;low\;Ca^{++}\;and\;Mg^{++}$ and T-C were the most crucial. We suggest technique development of the built-up planting ground for stability in the reclaimed land from the sea. The built-up planting grounds in reclaimed land from the sea, should be considered for the use of fair soil with the physical and chemical soil properties, -high level foundation of planting ground, and the prevention of disturbed soil-.

• 아시안잔디학회지
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• 제7권1호
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• pp.31-34
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• 1993

There is a growing concern in the United Stares over the environmental and human health implications associated with heavy use of water, pesticides, and inorganic ferilizers in maintaining picture perfect golf courses. There is also a growing awareness that a beautiful course is not necessarily a healthy course. The following discussion reviews the interrelationship of turfgrass and the soil that supports it and provides basic information on currently available alternatives to turf management practices that feature intensive application of inorganic fertilizers. water and pesticides. Soil is a dynamic natural environment in which microorganisms play an important role. Soil contains a large mass of microorganisms which produce thousands of enzymes that can catalyze the transformation and degradation of many organic molecules. (In top soil under optimum conditions may contain 10 billion cells per gram of soil.). Turfgrass and the soil which supports it are interdependent. The natural organic cycle as applied to turf and soil begins with healthy vigorous grass plants storing up the sun's energy in green plant tissues as chemical energy. Animals obtain energy by eating plants and when plants and animals die, their wastes are returned to the soil and provide "food" for soil microorganisms. In the next step of the organic cycle soil microorganisms break down complex plant tissues into more basic forms and make the nutrients available to grass roots. Finally, growing plants extract the available nutrients from the soil. By free operation of this organic cycle, natural grasslands have some of the most fertile soils on earths.

• 한국환경농학회지
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• 제15권3호
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• pp.372-382
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• 1996

토양 중 중금속들의 이동성 및 식물흡수와의 관계를 알기 위하여 만경강 중류에서는 전주공단의 공단폐수 및 생활하수가 유입되는 전주천의 영향을 주로 받고 하류에서는 익산지역의 공단폐수 및 생활하수가 유입되고 있는 만경강유역을 중심으로 토양시료 채취년도 (1982년과 1990년) 별 및 표 ${\cdot}$ 심토별로 추출방법을 달리하여 토양 중 중금속 함량 및 존재 형태를 분류하고, 1990년도 토양 시료 중 중금속 함량과 1990년도에 채취한 수도체 중 부위별 중금속 함량과의 상관관계를 조사 분석한 결과는 다음과 같다. 1. 각 중금속별 전 함량은 1990년 토양 중 함량이 1982년도 토양중 함량보다 표토에서 Cd가 3%, Zn 29%, Cu가 59%, Pb가 8% 증가하였고, 심토에서는 Cd가 8%, Zn 50% Cu가 91%, Pb가 8%로 증가하여 증가 비율이 Cu > Zn > Pb > Cd의 순서를 나타내었으며, Cd의 경우 연속 추출방식에 의한 화합물 형태는 유기물 결합형 > 묽은 산 추출형= Fe-Mn 산화물형 > 치환성 > 규산염결합형 순이었고 특히, 유기물 결합형태가 표토에서 $46.62{\sim}48.08%$ 심토에서 $41.18{\sim}50.18%$로 그 분포가 가장 많았다. 2. 산화물 및 규산염내에 결합되어 있어 비이동성인 중금속 비율은 표토에서 Cd가 21.25%, Pb가 35.98%, Cu가 74.18%, Zn이 82.12%였고, 치환성, 묽은산 추출형 및 유기적 결합형 등의 이동성은 17.88% 이상으로 Cd이 78.75%, Pb이 64.02%, Cu가 25.82%, Zn이 17.88%순으로 나타났다. 3. 표토 중에서 Pb를 제외하면 치환성, 묽은산 추출형태의 Cd, Zn, Cu등이 수도체의 엽신, 줄기, 화서축 중에 이들 농도를 높이는 상관성이 있었으나 심토 중 중금속 함량과 수도체 부위별 함량 간에는 모든 부위에서 유의적 상관성이 없었다.

• 한국환경복원기술학회지
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• 제12권2호
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• pp.29-39
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• 2009

Research was initiated to investigate a vegetation characteristics of the winter season by seeding periods. 3 seeding periods (Mid-December seeding plot, Late January seeding plot and Early March seeding plot) and 3 zones (the top zone, the middle zone and the bottom zone) in each plot were treated with 3 replications on the experimented slope. Data such as vegetation coverage (%), soil hardness (MPa), temperature ($^{\circ}C$) and moisture (%) content were analyzed. The vegetation coverage was high in Early March seeding plot, medium in Mid-December, and low in Late January seeding plot. Early March seeding plot was effective in moisture content, soil hardness, and temperature for the growth of vegetation when compared to Late January seeding plot and Mid-December seeding plot. From the standpoint of coverage ratio of plant species, the coverage of Dianthus sinensis and Albizzia julibrissin were high in the Late January seeding plot whereas the coverage of Lotus corniculatus and Cool-season turfgrass were high in Early March seeding plot. These results indicated that the high vegetation coverage of Dianthus sinensis and Albizzia julibrissin in Early March seeding plot was caused by scarification during winter season. There was no difference observed in plant height regardless of seeding periods except in early surveying time of May and June after seeding. As far as each zone of the plot was concerned, the vegetation coverage was high. in the bottom zone, medium in the middle zone and low in the top zone. The bottom area of the experimented slope was high in moisture content when compared to the middle zone and the top zone.

• Geomechanics and Engineering
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• 제22권2호
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• pp.153-163
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• 2020

Laboratory experiments were conducted with two different soil conditions to investigate rainfall infiltration characteristics. The soil layer materials that were tested were weathered granite soil and weathered gneiss soil. Artificial rainfall of 80 mm/hr was reproduced through the use of a rainfall device, and the volumetric water content and matric suction were measured. In the case of the granite soil, the saturation velocity and the moving direction of the wetting front were fast and upward, respectively, whereas in the case of the weathered gneiss soil, the velocity and direction were slow and downward, respectively. Rainfall penetrated and saturated from the bottom to the top as the hydraulic conductivity of the granite soil was higher than the infiltration capacity of the artificial rainfall. In contrast, as the hydraulic conductivity of the gneiss soil was lower than the infiltration capacity of the rainfall, ponding occurred on the surface: part of the rainfall first infiltrated, with the remaining rainfall subsequently flowing out. The unsaturated hydraulic conductivity function of weathered soils was determined and analyzed with matric suction and the effective degree of saturation.

• International Journal of Concrete Structures and Materials
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• 제8권3호
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• pp.239-249
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• 2014

In this paper, the analysis of a numerical study of pile-soil interaction subjected to axial and lateral loads is presented. An analysis of the composite pile-soil system was performed using the finite difference (FD) software LPILE. Two three dimensional, finite element (FE) models of pile-soil interaction have been developed using Abaqus/Cae and SAP2000 to study the effect of lateral loading on pile embedded in clay. A lateral displacement of 2 cm was applied to the top of the pile, which is embedded into the concrete pile cap, while maintaining a zero slope in a guided fixation. A comparison between the bending moments and lateral displacements along the depth of the pile obtained from the FD solutions and FE was performed. A parametric study was conducted to study the effect of crucial design parameters such as the soil's modulus of elasticity, radius of the soil surrounding the pile in Abaqus/Cae, and the number of springs in SAP2000. A close correlation is found between the results obtained by the FE models and the FD solution. The results indicated that increasing the amount of clay surrounding the piles reduces the induced bending moments and lateral displacements in the piles and hence increases its capacity to resist lateral loading.

• 한국연초학회지
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• 제3권2호
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• pp.103-108
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• 1981

This experiment was carried out to investigate effects of soil moisture content on the growth of tobacco plant at early stage after transplanting. Soil moisture was controlled to be 30%, 45%, 60%, 75% and 90% of the maximum water holding capacity (38.7%), and treated for 10, 20 and 30 days. Budding flowering and topping were delayed in the 30% and 45% treatment where soil moisture was deficient. Plant height, number of leaves, and length and width of the largest leaf were the best in the 75% treatment for 10 days, and development of the root and top was the best also in the same treatment. As the duration of low soil moisture treatment prolonged, intercellular space , became small. Nitrogen and potassium of the cured leaf showed the highest value in 30% and 45% treatments. Nicotine content of the cured leaf was high in the 90% treatment, and reducing sugar content of that was high in the 75% treatment for 10 days.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.423-428
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• 2005

If the load of constructing vehicles during the construction work acts on the road or the ground surface on the soft ground, due to the excess stresses in soils the trafficability of the vehicles influences the constructing efficiency, constructing period and so on. Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research represents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer for its vertical and horizontal stress in (1)homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stress turn out to be different in the value of theoretical and actual measurement after the trial examination of model.

• 한국철도학회논문집
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• 제8권1호
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• pp.57-62
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• 2005

The frost heaving pressure can be a problem for weakening of the railway roadbed material. This study was initiated to investigate the soils frost heaving pressure and physical characteristics(Liquid limit, permeability, SEM analysis) resulting from freezing and freezing-thawing cycle process. Therefore, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. Weathered granite soils, sandy soil were used in the laboratory freezing test which sometimes subjected to thermal gradients under closed-systems. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with elapsed time. The degree of saturation versus heaving pressure curve is also presented for weathered granite soil and the maximum pressure is closely related to this curve. Based on the laboratory test results, fine-grained soils with strong attractive forces between soil grains md water molecules, and additional water is attracted into the pores leading to further volume changes and ice segregation.