• Proceedings of the KSR Conference
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• 2003.05a
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• pp.46-52
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• 2003

In this study, the full scale testing method of the geogrid-reiuorced soil Segmental Retaining Walll(SRW) under the simulated train loading were proposed in order to evaluate the applicability of reinforced soil SRW in railway embankment. The train loading was simulated by the design static wheel load and the impact coefficient due to the train passing velocity. This test was focused on the static performance of reinforced soil SRW in terms of the following measuring systems ; the horizontal earth pressure displacement acting on the facing block and the tensile strain along the geogrid. The data gathered from this full scale testing was compared with numerical analysis results by FLAC.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.432-438
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• 2010

This study was carried out to understand the effect on soil chemical property, ion contents, and growth of Lonicera japonica by treatment of simulated acid rain and wood vinegar. It was treated total 30 times by one time per 2 weeks during 150 days from June to October dividing to various pH level of simulated acid rain (each pH 5.6, 4.5, 3.5 and 2.5) and the control site (pH 6.3). The wood vinegar diluted with 500 times was also treated total 10 times by one time per 2 weeks at the experimental sites. The soil pH was reduced as pH level of simulated acid rain was decreased. The organic content, total nitrogen, and Av. $P_2O_5$ in soil showed a tendency to increment. However, the soil improvement effect was exposed to be insufficient when a wood vinegar was treated. In the component of the plant body, $SO_4{^2}$ and $NO_3{^-}$ increased due to the simulated acid rain treatment and the increment ratio was reduced in the wood vinegar treatment plot. In addition, the cation contents showed a tendency to variation due to pH of simulated acid rain. And it showed more increment in the leaves than the root. The early fallen leaves and growth inhibition of L. japonica showed up after the simulated acid rain treatment but the growth of L. japonica increased after the wood vinegar treatment.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.282-284
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• 2003

Multi-phase extraction of LNAPLs not only floating on groundwater but also captured in soil pores was studied in a simulated soil system. The extraction rate of LNAPL under the MPE conditions was much higher than the rate under usual hydraulic gradient conditions. The WE might be especially useful for recovery of oils in fine-textured soils such as clay-dominant soils. The vacuum-enhanced transport of LNAPL in soils also depended on the properties of LNAPL such as viscosity and density as well as soil textures.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.237-243
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• 1992

To determine effects of simulated acid rain on the growth and yield of rice, soybean and sesame, and on the soil acidity, two cultivars of rice, soybean and sesame were exposed twice a week to one of four simulated rain acidities[pH 2. 6, 3. 6, 4. 6 and 5. 6(control)]. The plants were protected from ambient rain by a polyethylene film cover. No visible damage due to the simulated acid rain was observed at any stage of growth for either of the crops. In rice, heading date, plant height and yield components except ripening ratio were not significantly affected by the pH ofsimulated rain, but the ripening ratio and rough rice yield linearly decreased as the pH of simulated rain was decreased. In soybean, maturing date and yield components except 100 seed weight were not significantly influenced by the pH of simulated rain, but the 100 seed weight and yield linearly decreased as the pH of simulated rain was decreased. Seed yield and the other agronomic characteristics of sesame were not significantly affected by the pH of simulated rain. Soil pH after cropping rice, soybean and sesame decreased as pH of simulated rain was decreased.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.537-546
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• 2016

The development of models for agriculture systems, especially for crop production, has supported the prediction of crop yields under various environmental change scenarios and the selection of better crop species or cultivar. Crop models could be used as tools for supporting reasonable nutrient management approaches for agricultural land. This paper outlines the simplified structure of main crop models (crop growth model, crop-soil model, and crop-soil-environment model) frequently used in agricultural systems and shows diverse application of their simulated results. Crop growth models such as LINTUL, SUCROS, could provide simulated data for daily growth, potential production, and photosynthesis assimilate partitioning to various organs with different physiological stages, and for evaluating crop nutrient demand. Crop-Soil models (DSSAT, APSIM, WOFOST, QUEFTS) simulate growth, development, and yields of crops; soil processes describing nutrient uptake from root zone; and soil nutrient supply capability, e.g., mineralization/decomposition of soil organic matter. The crop model built for the DSSAT family software has limitations in spatial variability due to its simulation mechanism based on a single homogeneous field unit. To introduce well-performing crop models, the potential applications for crop-soil-environment models such as DSSAT, APSIM, or even a newly designed model, should first be compared. The parameterization of various crops under different cultivation conditions like those of intensive farming systems common in Korea, shortened crop growth period, should be considered as well as various resource inputs.

• Water Engineering Research
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• v.5 no.2
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• pp.55-68
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• 2004

The GLEAMS (Groundwater Loading Effects of Agricultural Management System, version 3.0) water quality model was used to predict hydrology and water quality and to evaluate the effects of soil types from a cattle-grazed pasture field of Bermuda-Rye grass rotation with poultry litter application as a fertilizer in North Alabama. The model was applied and evaluated by using four years (1999-2002) of field-measured data to compare the simulated results for the 2.71- ha Summerford watershed. $R^2$ values between observed and simulated runoff, sediment yields, TN, and TP were 0.91, 0.86, 0.95, and 0.69, respectively. EI (Efficiency Index) of these parameters were 0.86, 0.67, 0.70, and 0.48, respectively. The statistical parameters indicated that GLEAMS provided a reasonable estimation of the runoff, sediment yield, and nutrient losses at the studied watershed. The soil infiltration rates were compared with the rainfall events. Only high intensity rainfall events generated runoff from the watershed. The measured and predicted infiltration rates were higher during dry soil conditions than wet soil conditions. The ratio of runoff to precipitation was ranging from 2.2% to 8.8% with average of 4.3%. This shows that the project site had high infiltration and evapotranspiration which generated the low runoff. The ratio of runoff to precipitation according to soil types by the GLEAMS model appeared that Sa (Sequatchie fine sandy loam) soil type was higher and Wc (Waynesboro fine sandy loam, severely eroded rolling phase) soil type relatively lower than the weighted average of the soil types in the watershed. The model under-predicted runoff, sediment yields, TN, and TP in Wb (Waynesboro fine sandy loam, eroded undulating phase) and Wc soil types. General tendency of the predicted data was similar for all soil types. The model predicted the highest runoff in Sa soil type by 105% of the weighted average and the lowest runoff in Wc soil type by 87% of the weighted average

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.43-52
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• 1988

One-year-old seedlings of Ginkgo biloba were treated with various simulated acid rains(pH 2.0, pH 3.0, pH 9.0 and pH 5.0) to examine the effects of simulated acid rain on the chemical properties of the tested soil. The seedlings were grown in a pot($4500cm^3$)containing one of three different soils(nursery soil, mixed soil and sandy soil). Simulated acid rain was made by diluting sulfuric and nitric acid solution($H^1SO^4$ : $HNO^3$ =3 : 1, V/V) with tap water and tap water(pH 6.4), and treated by 5mm each time for three minutes during the growing seasons(April to October 1985). Acid rain treatments were done three times per week to potted seedlings by spraying the solutions. The chemical properties of potting media were compared among three soil types as well as among the various pH levels. The results obtained in this study were as follows : 1. Exchangeable calcium and magnesium contents and base saturation of the soil decreased with decreasing pH levels of acid rain, and their decreasing rates were as follows : sandy soil was the highest, followed by mixed and nursery soils, However, exchangeable aluminum content rather increased as the pH levels decreased. 2. Available phosphate in the soil decreased as the pH levels of acid rain decreased. Its content increased in nursery soil, compared with those before acid gain treatment, Gut decreased in mined and sandy soils. 3. Soil sulfate and nitrate contents increased remarkably as the pH levels decreased, and the only significant difference in the sulfate was found among the pH levels. Soil sulfate content was the highest in nursery soil, followed by mixed and sandy soils.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1870-1875
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• 2006

This study was carried out to investigate the applicability of SAC-SMA model with parameters which were derived from analytical relationships proposed by Koren etc. (2000), with various data of soil properties in a basin. The studied basin is Yongdam dam basin and the daily runoff with 2003-year hydrological data was simulated. Simulated runoff results were compared with those measured at three check points(Chuchun, Donhyang and Yongdam) and analyzed through the statistical techniques such as VE(Volume Error), RMSE(Root Mean Squared Error) and CORR(Correlation). As a result of analyses, the good agreement was obtained between simulated and measured results.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.156-160
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• 2002

실험적 베리오그램의 모델링에 SA(Simulated Annealing)기법을 이용하였다. 최소 자승법의 해를 구하기 위하여 기존의 상용 프로그램에서 많이 이용되고 있는 반복법에 근거한 방법에 비해서 SA 기법은 초기 가정값에 크게 영향을 받지 않고 일정한 모델 인자의 값을 제시하였다. 임의의 초기 가정값을 입력하여도 충분한 반복 계산을 통하여 목적함수의 값이 광역적 최소값으로 수렴하는 것을 확인할 수 있었다. 베리오그램 모델이 일반적으로 비선형 모델이기 때문에 목적함수의 지역적 최소값으로의 수렴이 문제가 되고 이로 인하여 구해지는 인자의 값이 정확하지 않을 수 있지만 SA 기법을 이용하여 최소 자승법의 해를 구하게 되면 정확한 인자의 값을 구할 수 있음을 확인하였다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.161-170
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• 2008

Interest is growing in applying simulation models for the South Texas conditions, to better assess crop water use and production with different crop management practices. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of com (Zea mays L.) in South Texas of the U.S. We measured actual crop evapotranspiration (ETc) using a weighing lysimeter, soil moisture using a neutron probe, and grain yield by field sampling. The model was then validated using the measured data. Simulated ETc using the Hargreaves-Samani equation was in agreement with the lysimeter measured ETc. Simulated soil moisture generally matched with the measured soil moisture. The EPIC model simulated the variability in grain yield with different irrigation regimes with $r^2$value of 0.69 and root mean square error of $0.5\;ton\;ha^{-1}$. Simulation results with farm data demonstrate that EPIC can be used as a decision support tool for com under irrigated conditions in South Texas. EPIC appears to be effective in making long term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for inseason irrigation management.