• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.310-317
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• 2016

This study aimed to evaluate the nutrient load balance from rice paddy fields with different topographies, alluvial plain and local valley. Continuous monitoring from May to September, 2013 was conducted for water quantification and qualification from alluvial plain in Yeoju region (32 ha) and local valley in Jincheon region (24 ha). The discharge rates of T-N from the alluvial plain were 57.2, 5.84, 22.7, and $5.20kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In case of local valley, T-N loads were 34.6, 4.73, 21.1, and $4.15kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In contrary, the T-P loads from the alluvial plain were 2.23, 2.22, 2.54, and $0.41kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. In case of local valley, T-P loads were 1.44, 1.57, 1.82, and $0.34kg\;ha^{-1}$ for irrigation, precipitation, drainage, and percolation, respectively. The nutrient contents in drainage water were influenced by the amount of waters, rainfall, and surface drainage water. The Pearson correlation analysis showed that rainfall was significantly correlated with nutrient loads from July to August due to the amount of runoff in local valley paddy field, and irrigation was related with nutrient loads of drainage from July to August. This study showed that paddy rice farming in alluvial plain and local valley might be beneficial to water quality protection.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.377-382
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• 2001

Mechanical behavior and electrical resistance change of CPDP (carbon particle dispersed plastic) composite consisting of epoxy resin and conductive carbon particle were investigated under monotonic loading and repeated loading-unloading. The electrical resistance almost linearly increased with increasing strain during loading and the residual electrical resistance was observed even after removing load. The value of the residual electrical resistance was dependent on the maximum strain under the applied stress. This result suggests that the estimation of maximum strain (i.e., damage) is possible by the measuring electrical resistance of composite. The behavior of electrical resistance change during and after loading was discussed on the basis of the results of microscopic deformation and fracture observation. Moreover, the relationship between the volume fraction of carbon particle and the electrical resistivity of CPDP was investigated in relation to the percolation theory. Simulation model of percolation structure was established by Monte Carlo method and the simulation result was compared to the experimental results. The electrical resistance change under applied loading was analyzed quantitatively using the percolation equation and a simple model for the critical volume fraction of carbon particle as a function of the mechanical stress. It was revealed that the prediction was in good agreement with the experimental result except in the region near the failure of material.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.231-240
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• 1987

With a purpose to obtain basic informaton for improving poorly drained soil, a pot experiment was conducted about the effect of percolation rate on growth and yield of rice under application of wollastonite and rice straw as soil conditioner. The sandy and clayey soils were selected to compare difference in effectiveness of poor drainage. The results were summarized as follows: 1. Increasing or percolation rate increased rice yield in both sandy and clayey soils, but the effectiveness on yield increase was greater in clayey soil than in sandy. 2. Various materials of soil solution produced from the process of soil reduction were high at the early growing stage, but they were gradually decreased at the later growing stage. 3. With increasing percolation rate, the contents of N, $P_2O_5$ and $K_2O$ in rice plant were decreased, but that of $SiO_2$ was increased. 4. The number of roots at harvest was greater with increased extension as infiltration rate was increased.

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.66-75
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• 1996

This study was carried out to examine the forest fire effect on water storage characteristics in the forests. Water storage capacity of the burned area was analyzed by several major factors, such as soil pore, maximum water content, effective water storage, and percolation rate. The results obtained from the analysis of major factors are as follows; The deeper soil depth, the less total pore, coarse pore, effective water storage, and percolation rate. However, fine pore increased slightly in both burned area and control plot. As compared with control plot, burned area showed lower percolation rate, coarse pore, and effective water storage, but higher values of fine pore. Directly after forest fire, the soil pore is little affected. But as the time passes, top soil structure changes and soil pore also is affected even in a deep soil. Estimated effective water storage was lower at top soil of Namcheon and at deep soil of Namha in all the burned areas, but slowly decreased in deep soil compared to control plots. Therefore it was concluded that forest water storage capacity was greatly affected by the forest fire.

• Polymer(Korea)
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• v.27 no.1
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• pp.40-45
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• 2003

In this work, the effect of different contents of $Fe_3O_4$ and temperature variation on the electrical conductivity ($\sigma$) in the polar acrylonitrile butadiene rubber (NBR)/$Fe_3O_4$ (magnetite) mixture system was investigated. It was found that the percolation threshold concept holds true for the conductive particle-filled composites where $\sigma$ indicates a nearly sharp increase when the concentration of magnetite in the mixture exceeds 22%. The temperature dependence of $\sigma$ was thermally activated below and at the percolation threshold ($P_c$). Magnetite acted as reinforcing and conductive filler for NBR. At room temperature and higher voltages, the electrical current was proportional to the square of voltage ($I{\propto}V^2$) for the composites which contain 30 phr of magnetite. Moreover, it was shown that the composites with magnetite of 50 phr showed the highest tensile strength and elongation at break, which was due to the formation of optimal physical interlock and crosslinking. The results of 100%, 200%, and 300% Young moduli said that the moduli are largely correlated with reinforcement effect of magnetite and viscosity of the blends from torque curve.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.246-254
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• 2015

This study explored the effect of rainfall pattern and soil characteristics on water management in rice paddy fields, using a soil water balance model, BUDGET. In two sites with different soil textural group, coarse loamy soil (Gangseo series) and fine soil (Hwadong series), respectively, we have monitored daily decrease of water depth, percolation rate, and groundwater table. The observed evapotranspiration (ET) was obtained from differences between water depth decrease and percolation rate. The root mean square difference values between observed and BUDGET-estimated ET ranged between 10% and 20% of the average observed ET. This is comparable to the measurement uncertainty, suggesting that the BUDGET model can provide reliable ET estimation for rice fields. In BUDGET model of this study, irrigation requirement was determined as minimum water need for maintaining water-saturated soil surface, assuming 100 mm of bund height and no lateral loss of water. The model results showed different water balance and irrigation requirement with the different soil profile and indicated that minimum percolation rate by plow pan could determine the irrigation requirement of rice paddy field. For the condition of different rainfall distribution, the results presented different irrigation period and amounts, representing the importance of securing water for irrigation against different rainfall pattern.

• Polymer(Korea)
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• v.34 no.2
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• pp.97-103
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• 2010

PMMA was grafted on MWCNT surface in order to prepare conducting film composed of 6FDAbased polyimide/MWCNT. The electrical conductivity of 6FDA-based polyimide/PMMA-g-MWCNT was investigated as a function of PMMA-g-MWCNT content. Dispersion of MWCNT in 6FDA-based polyimide composite film was better than the pristine MWCNT due to the interaction force between PMMA and 6FDA-based polyimide. Electrical conductivity was interpreted by percolation threshold theory. As a result, 6FDA-6FpDA/PMMA-g-MWCNT which have high critical exponents and low critical concentration showed better dispersion than polyimide composite material that contains DABA(diamino benzoic acid).

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.2
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• pp.99-110
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• 2005

Characteristics of concentrations of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) pollutant in percolated water at four paddy field sites (Soro, Odong, Munui, and Boeun) were investigated by a nonparametric test. Percolation rate measurement and percolated water sampling were taken during irrigation periods at $5{\sim}10$ day intervals. The normality of percolation rate and pollutant concentrations were examined using histogram, boxplot, and the Kolmogorov-Smirnov (K-S) test. Pollutant concentrations in percolated water showed positively skewed distribution. The median concentrations of pollutant were 1.91 mg/L for TN, 0.021 mg/L for TP, and 6.6 mg/L for COD, which were lower than its arithmetic mean concentrations by $35\%$ for TN, $36\%$ for TP, and $13\%$ for COD. The median concentrations of TN and TP differed significantly among sample sites according to the Kruskal-Wallis test. However, median concentrations were not significantly different among month except for TN and TP of Soro and COD of Odong. The percolation load of pollutants during irrigation periods in the study area were estimated at $3.12{\sim}7.75\;kg/ha$ for TN, $0.033{\sim}0.155\;kg/ha$ for TP, and 10.7 kg/ha for COD, which were much lower than respective values reported in Japan.

• Composites Research
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• v.17 no.5
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• pp.61-67
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• 2004

This paper reports the electrical conductivity and the stress-strain behavior of silver particle-filled silicone composite pastes for electromagnetic interference (EMI) shielding gasket materials. The percolation threshold (critical concentration) of the composite paste obtained by incorporating irregular sphere-shaped silver particles and room temperature vulcanizing (RTV) silicone resin was determined from the electrical conductivity result. At about 28 vol% Beading of untreated silver particles, the percolation phenomenon occurred and at this critical concentration, the volumetric resistivity, the tensile strength, and the elongation of the pastes were investigated. This work also suggests that the stress-strain characteristics of a composite paste filled with metal particles above the percolation threshold may be effectively improved by properly selecting a coupling agent.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.649-663
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• 2012

We propose a percolation based M2M networking architecture and its data transmission method. The proposed network architecture can be server-free and router-free, which allows us to operate routing efficiently with percolations based on six degrees of separation theory in small world network modeling. The data transmission can be divided into two phases: routing and data transmission phases. In the routing phase, probe packets will be transmitted and forwarded in the network thus multiple paths are selected and performed based on the constriction of the maximum hop number. In the second phase, the information will be encoded, say, with the fountain codes, and transmitted using the paths generated in the first phase. In such a way, an efficient routing and data transmission mechanism can be built, which allow us to construct a low-cost, flexible and ubiquitous network. Such a networking architecture and data transmission can be used in many M2M communications, such as the stub network of internet of things, and deep space networking, and so on.