• 한국농공학회논문집
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• 제58권3호
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• pp.47-56
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• 2016

Superabsorbent Polymers (SAPs) are hydrophilic synthetic polymers which could absorb water by hundreds of their own weight. They are used for multiple purpose including hygienic goods, soil conditioners, and hospital supplies. It is necessary to investigate the standard of their use including the amendment rate for soil application in agricultural fields. It is also important to understand their effects on the soil water content and engineering characteristics. The objective of this study is to find the water absorbing capacity and reusability of SAPs, and the characteristics of water release and effect of them on soil water content and engineering characteristics. In the result, SAPs per unit weight (1 g) used for this research could absorb about 200 g of water in max. The water absorbing capacity decreased after SAPs were used repeatedly. Released water of SAPs could provide the soils with about 9 % of the soil water content. Soil water content increased with decreasing distance from the SAPs. The distance of release was spreaded out with increasing water absorbed of SAPs. Finally, when a drainage and the capacity of soil water content were considered, it is recommended to amend the SAPs with soil by less than 0.25 %.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.147-152
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• 2001

This study investigated one-dimensional vertical infiltration to an unsaturated residual soil by numerical solutions, FDM. In order to estimate the parameters needed for numerical analysis, tire soil-water characteristic curve(SWCC) of Shinnae-dong soil, one of the most typical residual soils in Korea, were experimentally obtained. Then, the statistical analysis for obtaining the SWCC was performed. The numerical solution to the linearized governing equation for unsaturated groundwater flow provides the infiltration characteristics for the unsaturated residual soil represented by transient pressure profiles and water contents profiles.

• 한국토양비료학회지
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• 제50권5호
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• pp.336-344
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• 2017

The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high $R^2$ values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.

• 한국토양비료학회지
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• 제48권6호
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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 [${\Theta}sc$] (Eq. 1) was developed based on the log function (Eq. 2) and exponential function (Eq. 3). ${\Theta}sc=[({\Theta}-{\Theta}r)/({\Theta}s-{\Theta}r)]$ (Eq. 1) ${\Theta}sc=-0.196ln(H)+0.4888$ (Eq. 2) ${\Theta}sc=0.3804(H)^{(-0.448)}$ (Eq. 3) where, ${\Theta}$: water content (g/g %), ${\Theta}s$: water content at 0.1bar, ${\Theta}r$: 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.

• 한국습지학회지
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• 제3권1호
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• pp.61-73
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• 2001

This study was performed to survey the characteristics of surface water and soil in Wangdungjae wetland located at Chiri-Mountain. The results of survey summarized as follows; 1. The physico-chemical characteristics of surface water such as pH, temperature, and DO were in the range of 6.02-6.39, $13.5-24.3^{\circ}C$ and 3.81-9.97 mg/L, respectively. Also, the organic concentrations such as BOD and COD were in the range of 1.3-1.61 mg/L and 3.55-9.97 mg/L, respectively. The water quality of five different sampling sites showed the similar characteristics. 2. The physico- chemical characteristics of soil showed the different properties with the soil sampling depth. According to increasing sampling depth, cation exchange capacity (CEC) and electric conductivity (EC) increased but pH decreased. 3. The future survey and researches on surface water and soil environments are needed to preserve the Wangdungjae wetland at Chiri-mountain marsh.

• 한국농공학회논문집
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• 제56권2호
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• pp.37-46
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• 2014

Water for crop growth were supplied by irrigation in protected cultivation and these are accumulated in the soil and utilized for crop evapotranspiration. The study for analyzing soil moisture characteristics is necessary for adequate irrigation water and soil water management in protected cultivation. Soil moisture content, irrigation water quantity and meteorological data were monitored to analyze soil moisture increment and extraction characteristics in terms of soil layers and cucumber crop growth stages. In first cropping period, the total amount of irrigation water was 5.07 mm/day, soil moisture increment was 4.82 mm/day and soil moisture extraction was 5.56 mm/day. In second cropping period, the total amount of irrigation water was 4.82 mm/day, soil moisture increment was 4.65 mm/day and soil moisture extraction was 4.73 mm/day. Soil moisture extraction rate from 0 to 75 cm is 90.3 % in first cropping period and 79.1 % in second cropping period. The majority irrigation water were consumed in root zone, however, about 15 % of soil moisture were losses by infiltration in lower soil layer. Soil moisture extraction and extraction pattern of cucumber crop calculated in this study can be utilized as a basic data for irrigation water management in protected cultivation.

• 한국농공학회논문집
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• 제58권1호
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• pp.53-59
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• 2016

This study was conducted by the slump test and the consistency test of the fiber mixed soil which is soil reinforced with fiber as a reinforced material to investigate and estimate the difficulty degree of work and the proper water content. So I would like to present the fundamental data that establishes the work standard of the fiber mixed soil. In conclusion, in this study the slump value of the fiber mixed soil increases over-all according to the increase of the water content although it has a little difference of the increase range and it is smaller than one of the soil. It is estimated that the aggregating and throwing work of the fiber mixed soil would be fine when it has the about 25 % water content and the wall and floor plastering work is the about 30 % ~ 35 % and the flowing and pouring work is the about 40 % water content as well as the mold compacting work is the about 20 %. There is no decreasing of the workability when the soil is reinforced by the fiber because the workability characteristics of the fiber mixed soil is similar to the one of the soil. Therefore, It is estimated that using the fiber as a reinforced material of soil would be appropriate for the construction.

• 상하수도학회지
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• 제11권4호
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• pp.99-109
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• 1997

To estimate the nutrients delivery characteristics of Chogang stream to Keum River, sediment and soil characteristics were analyzed in the stream and in the stream bank. Along the stream, soil samples from river sediment were collected and tested monthly for phosphorus and nitrogen concentrations. Nitrogen concentration in the sediment is much lower than that of soil in the river bank especially in summer presumably due to the high desorption characteristics of nitrogen by the increasing rainfall energy during summer. Instead, the concentrations of phosphorus were similar for the sediment and the soil in the river bank due to the strong adsorption characteristics of phosphorus. Batch tests were performed to evaluate the desorption potential of the sediments. Universal Soil Loss Equation (USLE) was applied to quantify soil erosion in each watershed due to rainfall. It was estimated that approximately 25% of total phosphorus by mass basis could be released from the sediment if the water was disturbed vigorously. The mass load of nitrogen and phosphorus into the Chogang Stream from the watershed were evaluated from the USLE and release ratio of phosphorus.

• 한국산림과학회지
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• 제85권1호
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• pp.66-75
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• 1996

본 연구는 산불 발생이 임지의 수저류 특성에 미치는 영향을 알아보기 위해 실시했다. 비산불 지역과 산화적지를 대상으로 산림토양의 수저류능을 토양공극, 최대수분량, 이용가능수량, 그리고 투수율을 측정하여 비교 분석하였다. 주요 인자들의 측정에 의해서 얻어진 결과는 다음과 같다. 산화적지와 대조구에서 토성이 깊어질수록 전공극(全孔隙), 조공극(組孔隙), 이용가능 수량, 투수율은 모두 감소하는 경향을 나타내고, 세공극(細孔隙)은 약간 증가하는 경향이 있었다. 대조구에 비해 산화적지에서는 투수율, 조공극량 및 이용가능수량이 낮게 나타나는 반면, 세공극량은 높게 나타났다. 그리고 산불이 발생한 직후에는 산림토양의 공극량 분포에 큰 변화가 일어나지 않지만, 시간이 경과함에 따라 산화적지의 표토 공극분포에 변화를 일으키면서 서서히 토심 20-40cm까지 영향을 미치는 것으로 나타났다. 또한 토심변화에 따른 이용가능수량의 변화는 대조구에 비해 산화적지에서 상대적으로 큰 폭으로 감소하는 경향이 있었다. 이 결과로 산림의 수저류능은 산불에 의해 크게 영향을 받는 것을 알 수 있었다.

• 한국수자원학회논문집
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• 제42권6호
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• pp.433-443
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• 2009

토양수분에 관한 관심이 급증하면서 토양수분의 시공간적 특성을 이해하고자 하는 연구가 최근 꾸준히 일어나고 있다. 토양수분의 보다 나은 이해를 위해, 본 연구에서는 이에 대한 동역학을 추계학적 기법을 이용하여 기후변화에 따른 영향평가에 대한 적용을 염두에 둔 추계학적 토양수분모형을 제시하고자 하였다. 보다 현실적인 적용을 위하여 손실항을 세 가지로 구분하여 고려하였고 강우의 추계학적인 특성 역시 고려하였다. 모의 결과 본 연구에서 유도한 토양수분 모형으로 관측 자료를 적절하게 재현 할 수 있으며 토양수분이 계절별로 강수의 패턴에 따라 일정한 순환의 형태를 가짐을 재현하였다. 또한 CGCM3.1 자료를 이용한 미래 토양수분 상태 예측으로, 토양수분의 변동성이 현재보다 커질 것으로 예측되었다.