• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.426-437
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• 2004

To understand the phytoplankton community in adjacent waters of Ulchin nuclear power plant (UNPP), abundance and the size fractionated $chl-\alpha$ concentrations were evaluated through seasonal interval sampling from April 2003 to February 2004. A total of 211 different phytoplankton species was observed and mean abundance of phytoplankton in each study period ranged from 244,286 to 1,221,779 cells $L^{-1}$. The contributions of microplankton $(>20\mu{m})$ to total phytoplankton abundance ranged from 42.5 to 83.6% (average 66.1%) and those of nanoplankton $(>20\mu{m})$ ranged from 16.4 to 57.5% (average 33.9%). Total chl-$\alpha$ concentrations of phytoplankton ranged from 0.52 to $2.26\mu{g}\;L^{-1}$. The contribution of chl-$\alpha$ concentrations of microplankton was higher than that of nano- and picoplankton through the study period with exception of July 2008. The results of abundances and $chl-\alpha$ concentrations suggest that microplankton has an important role in adjacent waters of UNPP. The diminution of abundances and $chl-\alpha$ concentrations of phytoplankton was observed after passage through the cooling water system, but it was gradually recovered by mixing with the ambient waters. Our results suggested that the influence of thermal discharges on phytoplankton should be restricted within narrow limits around outlet area of thermal effluents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.156-162
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• 2004

In this paper, a technique that estimate the optimal capacity of the solar-wind hybrid power system for minimizing the total monthly electric power expenses is presented. The hybrid power system is assumed to be operated in connection with the utility power system and electric bill be paid for the power not covered by the hybrid system generation. Monthly generation cost is estimated based on total life-cycle cost analysis. The monthly utility power bill is assumed to be increased quadratically in proportion with the net utility power consumption which is the difference between the total monthly load minus the hybrid system generations. Test results demonstrate applications potential of the proposed technique.

• Journal of Power Electronics
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• v.9 no.2
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• pp.300-307
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• 2009

In this paper, design and control is proposed for a four input-series-output-series-connected ZVS full bridge converter for the photovoltaic power conditioning system (PCS). The novel topology for a photovoltaic (PV) DC/DC converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. The control scheme, including an input voltage controller is proposed to achieve equal sharing of the input voltage as well output voltages by a four series connected module. Design methods for ZVS power stage are also introduced. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three DC/DC converters with a 25-kW power rating and uses only one-third of the total PV PCS power. The 25-kW prototype PV DC/DC converter is introduced to verify experimentally the proposed topology. In addition, an experimental result shows that the proposed topology exhibits good performance.

• Journal of Power Electronics
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• v.16 no.1
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• pp.111-120
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• 2016

Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters' output voltage with the phase shift control approach. In addition, the system's efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.5
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• pp.2177-2193
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• 2018

This paper studies resource allocation schemes for the relay-aided cooperative system consisting of multiple source-destination pairs and decode-forward (DF) relays. Specially, relaying selection, multisubcarrier pairing and assignment, and power allocation are investigated jointly. We consider a combinatorial optimization problem on quality of experience (QoE) and energy consumption based on relay-aided cooperative system. For providing better QoE and lower energy consumption we formulate a multi-objective optimization problem to maximize the total mean opinion score (MOS) value and minimize the total power consumption. To this end, we employ the nondominated sorting genetic algorithm version II (NSGA-II) and obtain sets of Pareto optimal solutions. Specially, two formulas are devised for the optimal solutions of the multi-objective optimization problems with and without a service priority constraint. Moreover, simulation results show that the proposed schemes are superior to the existing ones.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.263-270
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• 2016

Background: In this study, microwave extraction was used, which is an effective method to extract useful bioactive substances as it requires low quantities of solvent and short time periods. The aim of this study was to determine the optimal extraction conditions for Agrimonia pilosa Ledeb. Methods and Results: The independent variables were ethanol concentration, microwave power, and extraction time, each of which had five levels. The dependent variables were total polyphenol and total flavonoid content, and DPPH radical scavenging activity. To determine the optimal extraction conditions for bioactive compounds, a response surface methodology was employed. Contour maps were generated from polynomial equations. The optimal conditions were then assumed by superimposing these contour maps. Based on the resulting graph, the optimal microwave extraction conditions for Agrimonia pilosa Ledeb were determined as 42 - 48% ethanol concentration, 240 - 280W microwave power, and 13 - 20 min of extraction time. Conclusions: Ethanol concentration had a significant effect on microwave extraction, in terms of total polyphenol and total flavonoid content, as well as DPPH radical scavenging activity. Microwave power and extraction time influenced the total polyphenol content, but not the total flavonoid content or the DPPH radical scavenging activity.

• Culinary science and hospitality research
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• v.20 no.5
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• pp.29-33
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• 2014

In this study, we examined the antioxidant activity of the naturaceutical extract in vitro using total phenolic contents, total flavonoids contents, DPPH radical scavenging activity, reducing power assay, and phenolic acid contents. The total phenolic and total flavonoids contents of naturaceutical extract were 5.46 mg/g, 2.21 mg/g, respectively. The DPPH radical scavenging activity of natraceutical extract varied from 18.77 ($200{\mu}g/mL$) to 3.44 ($1,000{\mu}g/mL$). The reducing power of the natraceutical extract absorbance varied from 1.07 (0.78 mg/mL) to 3.44 (12.5 mg/mL), and reducing power of extract presented a concentration-dependent activity increase. The highest amounts of trans-ferulic acid, p-hydroxybenzoic acid, p-coumaric acid, vanillin, vanillic acid, p-hydroxybenzaldehyde, and trans-cinnamic acid were observed in the naturaceutical extract at the levels of 750.79, 619.75, 531.34, 222.04, 219.28, 107.40, and $89.56{\mu}g/g$, respectively. The results imply that this antioxidant effect of the naturaceuticals extract could be harnessed in the management and prevention of degenerative diseases associated with oxidative stress.

• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.139-148
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• 1995

This study was carried out to investigate the effects of super heated steam on the physical and chemical changes of burley cut tobacco. Total sugar, total alkaloid, ether extracts, crude ash, total nitrogen and pH for leaf chemical constituents were analyzed. Filling power and fineness index for physical properties, and carbonyl compounds, phenol compounds, amonia, pH, hydrogen cyanide nicotine, carbon monoxide, total volatile base and tar for smoke components were also analyzed. The cut tobacco treated with super heated steam showed significant decrease in total sugar and total alkaloid. The filling power of the sample treated with the super heated steam system was increased abruptly when heated at over 250℃. The fineness index showed similar tendency to that of common toast method. Super heated steam treatment slightly decreased carbonyl compounds, phenol compounds, hydrogen cyanide, nicotine, carbon monoxide and tar in the tobacco. Especially the decrease of ammonia was the most remarkable. The pH of smoke was a little different compared with that in the common toast. The sensory test results showed that, compared to the common conveyer moving system, the tobacco treated with super heated steam system brought out more roasted flavor, lowered impact, irritation, and sting, further improved aftertaste, and lowered bitterness. The super heated steam treatment method used in the studies is expected to give better filling power, mild taste and toasted odor of tobacco than that of the common method for toast treatment. Key words : burley tobacco, super heated steam, expansion, toast.

• Bulletin of the Korean Mathematical Society
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• v.57 no.1
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• pp.245-250
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• 2020

Let γt(G) and τ(G) denote the total domination number and vertex cover number of graph G, respectively. In this paper, we study the total domination number of the central tree C(T) for a tree T. First, a relationship between the total domination number of C(T) and the vertex cover number of tree T is discussed. We characterize the central trees with equal total domination number and independence number. Applying the first result, we improve the upper bound on the total domination number of C(T) and solve one open problem posed by Kazemnejad et al..

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.252-255
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• 2009

This paper proposes a new loss minimization controller (LMC) for induction motor drive. The proposed LMC presents a strategy to minimize the total power losses of induction motor (IM), which is based on simplified equivalent circuit and simplified model of IM. The proposed controller using the field oriented control (FOC) method is to determine an optimal rotor flux for obtaining the minimum total power losses and higher efficiency. Simulation and experimental results are given to validate the effectiveness of the proposed method.