Transport, species-specific resource competition, and shallow water effects in coupled bio-physical ecosystem models for C. polykrikoides harmful algal blooms off the coast of Korea

This thesis examines the role of transport and environmental variables in determining the occurrence or suppression of harmful algal blooms (HABs). In the first part, a simple 2-D diagnostic model is used to hindcast HABs occurring off the coast of Korea using observations of averaged environmental factors including nutrient concentration. Hindcasting results using the model show that physical transport of HABs is of the same order of importance as the environmental conditions in controlling HABs. The model reproduces the interannual variability of the observe HABs off the coast of Korea. The relative importance of the environmental factors based on limiting functional analysis suggest that phosphate, ammonium, and temperature are the most important (in that order), and that nitrate and light limitations have very little influence on the behavior of HABs.In the second part, a modified version of the NPZD ecosystem model is used to examine the effects of species competition and nutrient limitation in the development of HABs. Solutions to the NPZD system of equations show that steady state (equilibrium) conditions cannot occur for two phytoplankton groups (one normal and one HAB) without the presence of zooplankton which effectively acts to replenish the nitrogen pool. When the zooplankton prefer different phytoplankton groups, different equilibrium states are found and depend on a threshold for nitrogen level that depends on functional group parameters (like growth and mortality rates). Solutions explain details of population dynamics underlying HABs and should be useful to find best-fit mode coefficients. In the third part, the NPZD model is modified to include a bottom boundary condition describing sediment nitrification-denitrification process that necessitates both the inclusion of a functional phytoplankton group that fixes nitrogen, and the phosphorus cycle. The model shows why previous models that do not include specified bottom boundary conditions unrealistically predict oligotrophic water in coastal regions, whereas inclusions of denitrification and nitrogen fixing group lead to phytoplankton spatial distributions consistent with observations

Optimization of the overall success probability of the energy harvesting cognitive wireless sensor networks

Wireless energy harvesting can improve the performance of cognitive wireless sensor networks (WSNs). This paper considers radio frequency (RF) energy harvesting from transmissions in the primary spectrum for cognitive WSNs. The overall success probability of the energy harvesting cognitive WSN depends on the transmission success probability and energy success probability. Using the tools from stochastic geometry, we show that the overall success probability can be optimized with respect to: 1) transmit power of the sensors; 2) transmit power of the primary transmitters; and 3) spatial density of the primary transmitters. In this context, an optimization algorithm is proposed to maximize the overall success probability of the WSNs. Simulation results show that the overall success probability and the throughput of the WSN can be significantly improved by optimizing the aforementioned three parameters. As RF energy harvesting can also be performed indoors, hence, our solution can be directly applied to the cognitive WSNs that are installed in smart buildings

Effects Of Key Financial Indicators On Earnings Management In Korea’s Ready Mixed Concrete Industry

Earnings management is the practice of deriving certain benefits by intervening in external financial reporting or misleading certain stakeholders through adjustments to accruals without cash flow involvement or with affecting cash flows through real activities. Using the models of Kothari et al. (2005) and Cohen et al. (2008) for accrual-based earnings management (AEM) and real activities earnings management (REM), respectively, we examined whether relationships exist between key financial indicators, such as cash flows from operations, operating income, and debt dependency level, and AEM and REM in the ready mixed concrete (RMC) industry in Korea. This study is the first to investigate earnings management in Korea’s RMC sector. Results showed that operating income and cash flows from operations are significantly negatively related to AEM and REM, consistent with the findings of previous research. By contrast, debt dependency exhibits no significant relationship with AEM and REM, contradicting the findings of most previous studies. As a moderating variable, operating income affects the relationship between cash flows from operations and earnings management with only REM. On these bases, we can infer that earnings management in the Korean RMC industry responds differently to key financial indicators with regards to AEM and REM practice. Overall, companies in the industry implement aggressive earnings management depending on operating income and cash generation ability level rather than debt dependency level. These findings provide important insights for people who are interested in accounting information on the RMC industry in Korea

Long distance fiber Bragg grating strain sensor interrogation using high speed Raman-based Fourier domain mode-locked fiber laser with recycled residual Raman pump

We propose a novel fiber Bragg grating (FBG) sensor interrogation system using a Raman-based Fourier domain mode locking (FDML) fiber laser for a high speed and a long distance measurement. To improve transmission efficiency of the sensing probe signal over a long distance of 20-km, the residual pump powers are recycled. The external strain change can be measured by detecting the tine interval between two reflected signals from two FBGs as the Rama-based FDML is swept. The measured strain sensitivities with respect to the time are 0.19 ns/μstrain

Current status of convective clouds discrimination in NMSC/KMA

Póster presentado en: 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019

Energy harvesting non-orthogonal multiple access system with multi-antenna relay and base station

In this paper, we consider downlink non-orthogonal multiple access cooperative communication system. The base station (BS) serves two types of users, which are named relay user (RU) and far user (FU). The BS and RU are equipped with multiple transmit antennas. The RU harvests energy from the BS transmissions to perform the relaying operation for the FU. We have considered 1) amplify-forward; 2) decode-forward; and 3) quantize-map-forward relaying protocols at the RU. As the BS and RU have multiple antennas, therefore we consider 1) beamforming and 2) random antenna selection strategies at the BS and RU. Closed form expressions for the outage probability are provided for the aforementioned relay protocols and antenna strategies. Further, we show that for certain data rate range of the relay and FU the quantize-map-forward relaying protocol can perform better than the other two relaying protocols

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Korean language journalThe purpose of this study was to examine for the deference of leisure activities attitude compared with Korean and America university students' characteristics of leisure activities attitude in subcategory factors of leisure activities attitude include recognitive attitude, definitive attitude, behavioral attitude. 241 M,H,Y university students in Korea and 143 North Carolina N university students are responded survey for this study from 2007, May to August. The collected data based of survey are analyzed through frequency analysis, t- test, one-way ANOV A analysis by SPSS WIN ver 12.0. The result is following : First, there were statistical difference of leisure activities attitude in behavioral attitude between Korean students and America students. Second, there were statistical difference shows difference grade sector, own major, personal expenses in recognitive attitude. Third, the statistical difference shows grade sector, personal expenses in definitive attitude. Forth, the statistical difference shows grade sector, own major and personal expenses in of behavioral attitude

Origin of multi-level switching and telegraphic noise in organic nanocomposite memory devices.

The origin of negative differential resistance (NDR) and its derivative intermediate resistive states (IRSs) of nanocomposite memory systems have not been clearly analyzed for the past decade. To address this issue, we investigate the current fluctuations of organic nanocomposite memory devices with NDR and the IRSs under various temperature conditions. The 1/f noise scaling behaviors at various temperature conditions in the IRSs and telegraphic noise in NDR indicate the localized current pathways in the organic nanocomposite layers for each IRS. The clearly observed telegraphic noise with a long characteristic time in NDR at low temperature indicates that the localized current pathways for the IRSs are attributed to trapping/de-trapping at the deep trap levels in NDR. This study will be useful for the development and tuning of multi-bit storable organic nanocomposite memory device systems

Assessment of satellite rainfall nowcasting based on extrapolation technique

Póster presentado en: 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019