• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.332-342
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• 2010

A model has been developed to investigate in-river sediment and phosphorus dynamics. This advective-dispersive model is coupled with hydrodynamics and sediment transport submodels to simulate suspended sediment, total dissolved phosphorus, total phosphorus, and particulate phosphorus concentrations under unsteady flow conditions. It emphasizes sediment and phosphorus dynamics in unsteady flow conditions, in which the study differs from many previous solute transport studies, conducted in relatively steady flow conditions. The diffusion wave approaximation was employed for unsteady flow simulations. The first-order adsorption and linear adsorption isotherm model was used on the basis of the three-layered riverbed submodel with riverbed sediment exchange and erosion/deposition processes. Various numerical methods were tested to select a method that had minimal numerical dispersion under unsteady flow conditions. The responses of the model to the change of model parameter values were tested as well.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.57-65
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• 2012

Phosphorous is an essential element for the synthesis of various biomolecules including phospholipids, carbohydrates and nucleic acids. Bacterial cells can uptake it as forms of phosphate and phosphate-containing nutrients from extracellular environments, and reserve extra phosphate to polyphosphate inside the cell. Among five phosphate transport systems, Pst plays central roles in phosphate transport, and its expression is coordinated by the regulation of PhoB-PhoR two component signal transduction system in response to extracellular levels of phosphate. Genomic studies on the response regulator PhoB reveal many genes independent of phosphate metabolism. Based on recent findings on phenotypes of bacteria lacking proper function of each phosphate transport system, this review discusses roles of phosphate transporters in maintaining optimum intracellular phosphate levels, and presents diverse phenotypes of phosphate transporters related with other environmental signals as well as phosphate, then finally points out functional redundancy among phosphate transport systems or their regulators, which emphasize importance of phosphate homeostasis in governing metabolism, adaptation, and virulence of bacteria.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.113-117
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• 2016

Temperature dependent reverse-bias current-voltage (I-V) characteristics in Cu Schottky contacts to oxygen plasma treated n-InP were investigated. For untreated sample, current transport mechanisms at low and high temperatures were explained by thermionic emission (TE) and TE combined with barrier lowering, respectively. For plasma treated sample, experimental I-V data were explained by TE or TE combined with barrier lowering models at low and high temperatures. However, the current transport was explained by a thermionic field emission (TFE) model at intermediate temperatures. From X-ray photoemission spectroscopy (XPS) measurements, phosphorus vacancies (VP) were suggested to be generated after oxygen plasma treatment. V_P possibly involves defects contributing to the current transport at intermediate temperatures. Therefore, minimizing the generation of these defects after oxygen plasma treatment is required to reduce the reverse-bias leakage current.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1165-1167
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• 2007

Delta doping method can separate the threshold voltage control region from the charge transport region in a-Si TFT, whereby the threshold voltage of a TFT could be modified. Threshold voltage could be changed by delta doping, while field effect mobility was estimated to be 80% of that of standard TFT.

• KCID journal
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• v.19 no.1
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• pp.40-49
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• 2012

This study was performed to monitor the runoff of sandy soils on alpine uplands between March 2008 and December 2009, and assess non-point source pollution load. The fields were used to cultivete poteto in 2008 and radish in 2009. The fertilizers used in 200S, compared to those used in 2009, contained 2.1 times of nitrogen, 1.9 times of phosphorous, and 2.3 times of potassium. In 2008, the annual pollution load indiceted SS 2,908.47kg/ha/yr, COD 67.95kg/ha/yr, BOD 50.72kg/ha/yr, TN l3.29kg/ha/yr, and TP 9.97kg/ha/yr. In 2009, the annual pollution load indiceted SS 3,908.34kg/ha/yr, COD 225.04kg/ha/yr, BOD 156.96kg/ha/yr, TN 18.88kg/ha/yr, and TP 36.41kg/ha/yr. The amount of fertilizers used was about twice greeter in 2008, but the amounts of TN in pollution load per unit of rainfall were similar by 0.031kg/ha/mm to 0.029kg/ha/mm, whereas the amounts of COD (0.16kg/ha/mm to 0.35kg/ha/mm), BOD (0.12kg/ha/mm to 0.24kg/ha/mm), and TP (0.023kg/ha/mm to 0.057kg/ha/mm) doubled in 2009. We can infer thet the surface covering by the growth of crop mainly affected the transport of T-N through the subsurface flow to reduce non-point source pollution.

• Journal of the Korean GEO-environmental Society
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• v.15 no.4
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• pp.29-36
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• 2014

The purpose of this study investigates the delivery characteristics according to the load of pollutants by calculating the delivery rate of targeted areas on pollutants in Sapkyo reservoir. The main rivers of Sapkyo reservoir are Namwoncheon, Dogocheon, Sapkyocheon, Muhancheon and Gokgyocheon. The delivery rate and their characteristics of five major rivers during rainfall season are investigated. As th result, biochemical oxygen demand (BOD), total nitrogen (T-N) and total phosphorous (T-P) of total delivery rate are calculated by 0.40, 0.34 and 0.08, respectively. The delivery rate of T-P compares to other water quality is investigated relatively low. Looked at the overall characteristics of the watershed, the delivery rate of T-N and T-P is little change in the rate of the year, too. The delivery rate of T-N is calculated from 0.2 to 0.3 in the dry season, and from 0.31 to 0.39 in a flood, respectively. The delivery rate of T-P is calculated to more than 0.3 in the dry season, and 0.11 in a flood. It is similar values which the average annual delivery rate of T-P is 0.08. Therefore, the measured delivery rate of Sapkyo reservoir can be applicable such as a delivery rate of similar features of the terrain and land use.