Reddy S.S.,Woosong University
IEEE Transactions on Power Systems | Year: 2017
This paper proposes a new congestion management (CM) approach by using the generation rescheduling and load shedding, with the realistic voltage-dependent load modeling. The paper presents several objective functions such as generation and load shedding cost minimization (GLCM)/social welfare maximization including demand response offers (SWM), load shedding minimization (Pshd M), load served maximization (LSM), and load served error minimization. To the best of our knowledge, all previous CM efforts considered constant load models. Using voltage-dependent load models, the paper clearly brings out the inappropriateness of conventional single objectives for CM, such as GLCM/SWM and PshdM, due to the reduction of amount of load served. Therefore, multi-objective optimization is required and the objectives can be judiciously combined depending on the loading condition. Multi-objective strength pareto evolutionary algorithm 2+ has been employed to solve the proposed CM problem. The effectiveness of the developed approach is confirmed from the simulation results on IEEE 30 bus test system. © 1969-2012 IEEE.
Reddy S.S.,Woosong University
Electrical Engineering | Year: 2017
An efficient meta-heuristic algorithm-based multi-objective optimization (MOO) technique for solving the multi-objective optimal power flow (MO-OPF) problem using incremental power flow model based on sensitivities and some heuristics is proposed in this paper. This paper is aimed to overcome the drawback of traditional MOO approach, i.e., the computational burden. By using the proposed efficient approach, the number of power flows to be performed is reduced substantially, resulting the solution speed up. In this paper, the generation cost minimization and transmission loss minimization are considered as the objective functions. The effectiveness of the proposed approach is examined on IEEE 30 and 300 bus test systems. All the simulation studies indicate that the proposed efficient MOO approach is approximately 10 times faster than the evolutionary-based MOO algorithms. In this paper, some of the case studies are also performed considering the practical voltage-dependent load modeling. The simulation results obtained using the proposed efficient approach are also compared with the evolutionary-based Non-dominated Sorting Genetic Algorithm-2 (NSGA-II) and the classical weighted summation approach. © 2017 Springer-Verlag Berlin Heidelberg
Reddy S.S.,Woosong University
Renewable Energy | Year: 2017
The incorporation of renewable energy resources (RERs) into electrical grid is very challenging problem due to their intermittent nature. This paper solves an optimal scheduling problem considering the hybrid generation system. The primary components of hybrid power system include conventional thermal generators, wind farms and solar photovoltaic (PV) modules with batteries. The main critical problem in operating the wind farm or solar PV plant is that these RERs cannot be scheduled in the same manner as conventional generators, because they involve climate factors such as wind velocity and solar irradiation. This paper proposes a new strategy for the optimal scheduling problem taking into account the impact of uncertainties in wind, solar PV and load demand forecasts. The simulation results for IEEE 30 and 300 bus test systems with Genetic Algorithm (GA) and Two-Point Estimate Method (2PEM) have been obtained to test the effectiveness of the proposed optimal scheduling strategy. Results for sample systems with GA and two-point estimate based optimal power flow, and GA and Monte Carlo Simulation (MCS) have been obtained to ascertain the effectiveness of proposed method. Some of the results are also compared with the Interior Point method. From the simulation studies, it can be observed that with a marginal increase in the cost of day-ahead generation schedule, a substantial reduction in real time mean adjustment cost is obtained. © 2016 Elsevier Ltd
Sung B.,Woosong University |
Song W.-Y.,Dongseo University
Energy Policy | Year: 2013
This article investigates the causal relationship between public policies and exports of renewable energy technologies using panel data from 18 countries for the period 1991-2007. A number of panel unit root and cointegration tests are applied. Time series data on public policies and exports are integrated and cointegrated. The dynamic OLS results indicate that in the long run, a 1% increase in government R&D expenditures (RAD) increases exports (EX) by 0.819%. EX and RAD variables respond to deviations from the long-run equilibrium in the previous period. Additionally, the Blundell-Bond system generalized methods of moments (GMM) is employed to conduct a panel causality test in a vector error-correction mechanism (VECM) setting. Evidence of a bidirectional and short-run, and strong causal relationship between EX and the contribution of renewable energy to the total energy supply (CRES) is uncovered. CRES has a negative effect on EX, whereas EX has a positive effect on CRES. We suggest some policy implications based on the results of this study. © 2012 Elsevier Ltd.
Byun M.-W.,Woosong University
Journal of the Korean Society of Food Science and Nutrition | Year: 2013
This study examined the immunomodulatory activities of apple seed extracts (ASE). The immunomodulatory effects were estimated through nitric oxide production, cytokine induction, protein expression of inducible nitric oxide synthase (iNOS), and the phosphylation of mitogen-activated protein kinases (MAPKs) and inhibitory kappa Bα (IκB-α) in the RAW 264.7 macrophage cell line. In the cytotoxicity asay, ASE (31 to 250 μg/mL) did not induce cytotoxicity; thus, the optimal concentration of ASE was confirmed to be less than 250 μg/mL. Nitric oxide (NO) and cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-6) production significantly increased in a dose-dependent manner. Similarly, the protein expression of iNOS and the phosphorylation of MAPKs and IκB-α were also increased by ASE treatment. Overall, our results suggest that extracts from apple seeds potentially have immunomodulatory activities on macrophages. © 2013 by The Korean Society of Food Science and Nutrition. All rights reserved.
Sung B.,Woosong University
Renewable and Sustainable Energy Reviews | Year: 2015
This study investigates the effects of public policy supports on the export performance of bioenergy technologies; it uses panel data from 18 countries from the 1992 to 2008 period. Panel unit-root and cointegration tests are applied, taking into account the results of structural-break tests for each time series and testing for the presence in the panel of cross-sectional dependence. Time-series data on public supports and exports are integrated and cointegrated. The results of dynamic ordinary least squares indicate that in the long term, public R&D expenditures have a positive effect on the exports, the contribution of bioenergy to the total energy supply has a negative effect on the exports, and GDP has a positive effect on the exports. The contribution of bioenergy to total energy supply responds to deviations in the previous period from the longterm equilibrium. Additionally, Blundell-Bond system generalized methods of moments estimations are made, to determine dynamic causality in a panel vector error correction mechanism setting. Evidence of a positive strong and short-term relationship from exports to R&D expenditures, and of a positive short-term causality from exports to the contribution of bioenergy to total energy supply, is found. A positive strong bidirectional relationship between GDP and exports is also uncovered. There is a positive strong, bidirectional, and shortterm relationship between GDP and the contribution of bioenergy to total energy supply. Finally, some policy implications based on the results of this study are offered. © 2014 Elsevier Ltd. All rights reserved.
Byun M.-W.,Woosong University
Journal of Medicinal Food | Year: 2014
Inflammatory diseases remain the leading cause of mortality worldwide in both men and women. Schizonepeta tenuifolia (ST) exerts a wide range of physiological activities and has been found to possess beneficial efficacies against inflammation-related diseases; however, the molecular mechanisms underlying this anti-inflammatory activity remain to be elucidated. We investigated the molecular basis for the downregulation of toll-like receptor 4 (TLR4) signal transduction by ST ethanol extract in lipopolysaccharide (LPS)-stimulated macrophages. In this study, ST ethanol extract (100 μg/mL) did not induce cell cytotoxicity and was used in all the following experiments. Treatment of LPS-stimulated macrophages with ST ethanol extract resulted in a significant decrease in cyclooxygenase-2 and prostaglandin E2 levels, and inducible nitric oxide synthase-mediated NO production. LPS-induced expression of cell surface molecules (CD80 and CD86) and production of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-1β, and IL-6) were inhibited by ST ethanol extract. Further, we also found that the anti-inflammatory activities of ST ethanol extract was caused by inhibition of LPS-induced activation of mitogen-activated protein kinases, such as extracellular signal-regulated kinase 1/2 and p38, and the translocation of nuclear factor κB through TLR4 in macrophages. Thus, ST ethanol extract may possess novel and potent therapeutic efficacy for the treatment of inflammatory disease. © 2014, Mary Ann Liebert, Inc.
Park J.-S.,Seoul Metropolitan Government Research Institute of Public Health and Environment |
Lee G.-H.,Woosong University
Journal of the Science of Food and Agriculture | Year: 2011
Background: To investigate the volatile compounds and the antibacterial and antioxidant effects of the essential oils of Pinus densiflora needles (EPDN) and Pinus thunbergii needles (EPTN), the volatile compounds of steam-distilled essential oils were analysed by gas chromatography-mass spectrometry. Antibacterial activities were analysed by performing disc-agar diffusion assay and determining the minimum inhibitory concentrations (MICs) of the essential oils. Antioxidant activities were analysed via radical- and nitrite-scavenging activity assays. Results: The yields of EPDN and EPTN were 0.304% (v/w) and 0.296% (v/w), respectively. In the antibacterial activity assay, the MICs of EPDN and EPTN for Klebsiella pneumoniae, Shigella flexneri and Proteus vulgaris were < 0.4 mg mL-1. In the antioxidant activity assay, the 50% inhibitory concentrations (IC50) of EPDN and EPTN were 120 and 30 μg mL-1, respectively. At 1680 μg mL-1, both EPDN and EPTN exhibited > 50% nitrite-scavenging activity. Conclusion: EPDN can be used as a natural antimicrobial substance. Copyright © 2011 Society of Chemical Industry.
Lho Y.H.,Woosong University
Journal of Institute of Control, Robotics and Systems | Year: 2012
DC/DC switching power converters produce DC output voltages from different stable DC input sources regulated by a bi-polar transistor. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The voltage mode DC/DC converter is composed of a PWM (Pulse Width Modulation) controller, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an inductor, and capacitors, etc. PWM is applied to control and regulate the total output voltage. It is shown that the output of DC/DC converter depends on the variation of threshold voltage at MOSFET and the variation of pulse width. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by SPICE (Simulation Program with Integrated Circuit Emphasis) and experiments. © ICROS 2012.
Oh H.S.,Woosong University
Pediatric Infection and Vaccine | Year: 2015
Purpose: The aim of study was to estimate the hand hygiene (HH) compliance of healthcare workers (HCWs) in a children’s hospital. Methods: This study was conducted in a hospital which is a tertiary and educational children’s hospital with 313 beds and 533 HCWs. Data were collected by direct observation methods from November 1, 2010 to December 31, 2010. Results: A total of 2,999 opportunities for HH were observed, and the overall HH rate was 95.3%. HH rate of the registered nurse, physicians and transferer was 97.7%, 89.2%, and 72.1%, respectively (P <0.001). Among physicians, HH rate of the fellows, professors, residents and interns was 97.5%, 93.9%, 89.7%, and 80.9%, respectively (P <0.001). HH rate in the emergency room, operation room, outpatient department (OPD), and the intensive care unit (ICU) was 97.2%, 97.2%, 95.4%, and 92.5%, respectively (P <0.001). Hand rubbing was the most frequently used (81.1%), and hand washing was frequently used in the case of ‘after body fluids exposure risk’ (37.7%) and ‘after touching patient surroundings’ (28.5%). HH methods were not statistically different from each departments (P =0.083), however, they were significantly different according to the World Health Organization (WHO) 5 Moments (P <0.001). Distributions in WHO 5 Moments by the job titles were significantly different (P <0.001). The odds ratio of physicians, ICU and OPD was 0.353 (95% CI, 0.241-0.519), 0.291 (95% CI, 0.174-0.487), and 0.484 (95% CI, 0.281-0.834), respectively. Conclusions: Compliance of HH was different by the job titles and departments. Effective custom-tailored HH programs for each job title and department need to be developed. © 2015, Korean Society of Pediatric Infectious Diseases. All rights reserved.