• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.585-597
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• 2018

This study aims to investigate the variation of water quality and discharge under the condition of climate change and Best Management Practices (BMPs), which is one of the reduction methods for non-point source pollution. Soil and Water Assessment Tool (SWAT) model is applied to case in Cheongmicheon watershed. The coefficients required for SWAT model were calibrated using SWAT Calibration and Uncertainty Program. Climate change is considered by using Representative Concentration Pathway (RCP) scenarios, RCP 4.5 and RCP 8.5. It is known from simulation results that the non-point source pollutant increases under the climate change scenario assuming worse condition. It is also found in this study that an appropriate application of BMPs is able to reduce the quantity and temporal variation of non-point source pollutant effectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.5
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• pp.372-378
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• 2007

GHX (Geothermal Heat Exchanger) design which determines the performance and initial cost is the most important factor in ground source heat pump system. Performance of GHX is strongly dependent on the thermal resistance of soil, grout and pipe. In general, GHX design is based on the static simulation program. In this study, dynamic simulation has been peformed to analyze the variation of system performance for various GHX parameters. Line-source theory has been applied to calculate the variation of ground temperature. The averaged weather data measured during a 10-year period $(1991\sim2000)$ in Seoul is used to calculate cooling and heating loads of a building with a floor area of $100m^2$. The simulation results indicate that thermal properties of borehole play significant effect on the overall performance. Change of grout thermal conductivity from 0.4 to $3.0W/(m^{\circ}C)$ increases COP of heating by 9.4% and cooling by 17%. Change of soil thermal conductivity from 1.5 to $4.0W/(m^{\circ}C)$ increases COP of heating by 13.3% and cooling by 4.4%. Change of GHX(length from 100 to 200 m increases COP of heating by 10.6% and cooling by 10.2%. To study long term performance, dynamic simulation has been conducted for a 20-year period and the result showed that soil temperature decreases by $1^{\circ}C$, heating COP decreases by 2.7% and cooling COP decreases by 1.4%.

• Journal of Environmental Science International
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• v.16 no.1
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• pp.45-53
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• 2007

This study was carried out to investigate the variation of organic, nitrogen and phosphorus in $(AO)_2$ SBBR process according to the variation of operating cycle at the high TOC concentration. The operation time in anoxic (anaerobic) time to oxic time was 1:1. Three lab-scale SBBRS were fed with synthetic wastewater based on glucose as carbon source, The variation of total TOC removal was similar each other irrespective of operation time, however, the TOC concentrations in SBBRs showed a little difference according to the operating condition. In SBBR, complete nitrification was not occurred at all reactors, however, R3 showed a higher nitrification than R2. And in SBBR, the variation of operating time more affected at phosphorus removal than nitrogen removal. R2 which had the shortest time at the 1st aeration time showed the lowest phosphorus release and uptake efficacy.

• The Plant Pathology Journal
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• v.37 no.1
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• pp.1-23
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• 2021

Resistance to diseases caused by turnip mosaic virus (TuMV) in crop species of the family Brassicaceae has been studied extensively, especially in members of the genus Brassica. The variation in response observed on resistant and susceptible plants inoculated with different isolates of TuMV is due to a combination of the variation in the plant resistome and the variation in the virus genome. Here, we review the breadth of this variation, both at the level of variation in TuMV sequences, with one eye towards the phylogeny and evolution of the virus, and another eye towards the nature of the various responses observed in susceptible vs. different types of resistance responses. The analyses of the viral genomes allowed comparisons of pathotyped viruses on particular indicator hosts to produce clusters of host types, while the inclusion of phylogeny data and geographic location allowed the formation of the host/geographic cluster groups, the derivation of both of which are presented here. Various studies on resistance determination in particular brassica crops sometimes led to further genetic studies, in many cases to include the mapping of genes, and in some cases to the actual identification of the genes. In addition to summarizing the results from such studies done in brassica crops, as well as in radish and Arabidopsis (the latter as a potential source of candidate genes for brassica and radish), we also summarize work done using nonconventional approaches to obtaining resistance to TuMV.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1174-1179
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• 2009

In this paper we develop the characteristic of density on non-uniform plasma in different layer of the semiconductor with optically controlled microwave pulses. The transient response of the microwave pulses in different plasma layer has been evaluated by calculating the variation of the reflection function of dielectric microstrip lines. The lines has used under open-ended termination containing optically induced plasma region, which has illuminated a laser source. The characteristics impedances resulting from the presence of plasma are evaluated by the transmission line model. The analyzes the variation of transient response in a 0.01cm layer near the surface for frequency range from 1GHz to 128GHz. The diffusion length LD is larger than compared to the absorption depth $l/_{\alpha}l$. The variation of characteristic response in plasma layer with microwave pulses which has in deferentially localized has been evaluated analytically.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.5
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• pp.213-217
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• 2012

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases under thermal chemical vapor deposition system. By the incorporation of $SF_6$ additive in cyclic modulation manner, the dominant formation of the nanosized carbon coils could be achieved with maintaining the minimized sulfur additive amount. The geometry variation of the as-grown carbon coils, such as linear type, microsized coil type, wavelike nanosized coil type, and nanosized coil type, were investigated according to the different cyclic modulation manner of $SF_6$ flow. $SF_6$ gas incorporation develops the coil-type geometry. Furthermore, the higher flow rate of $SF_6$ gas increased the amount of the nanosized carbon coils. The slightly increased etching ability by $SF_6$ addition seems to be the cause for these results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.186-187
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• 2007

In this work, a temperature stable PWM(Pulse width modulation) circuit is proposed. The designed PWM circuit has a temperature dependent current source and a temperature independent voltage to compensate electrical characteristics with operating temperature. The variation of driving current is from about 4% to -6% in the temperature range $0^{\circ}C\;to\;70^{\circ}C$ compared to the current at the room temperature. The variation of bandgap voltage reference is from about 1.3% to -0.2% with temperature when the supply voltage is 3.3 volts. From simulation results, the variation of output pulse width is less than from 0.86% to -0.38% in the temperature range $0^{\circ}C\;to\;70^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.64-69
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• 2014

There are 440V and 220V electric source in ship. A 440V source is used to drive the power system such as crane and winch on deck and pump in engine room, and a 220V source is used to drive the power source for residential zones, control devices in engine room. In this paper, we made single phase inverter system for grid connection with 220V source for ship, and analyzed THD(Total harmonic distortion) by variation of parameters of L-C low pass filter and deadtime of inverter switching.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.91-102
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• 2013

This paper proposes the improved LCCT(Inductor-Capacitor-Capacitor-Trans) Z-source DC-DC converter (Improved LCCT ZSDC) which can generate the bipolar output voltages according to duty ratio D. The proposed converter has the characteristic and structure of Quasi Z-source DC-DC converter(Quasi ZSDC) and conventional LCCT Z-source DC-DC converter(LCCT ZSDC). To confirm the validity of the proposed method, PSIM simulation and a DSP based experiment were performed for each converter. In case which the input DC voltage is 70V, the bipolar output DC voltage of positive 90V and negative 50V could generate. Also, as comparison result of the capacitor voltage ripple in Z-network and the input current under the same condition for each converter, the voltage stress and the capacitor voltage in Z-network of the proposed method were lower compared with the conventional methods. Finally, the efficiency for each method was investigated according to load variation and duty ratio D.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.697-704
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• 2008

Stormwater runoff from urban road area as non-point source has a tendency of including lots of pollutants at initial rain period. Recently, there are several cases of having installed treatment facilities for reducing pollution discharge from the impervious cover in urban area to prevent watershed environment from getting worse. The filtration type among non-point source treatment systems has been known as one of the most efficient system for treatment of non-point source pollutants. Therefore, various kinds of filter media such as expanded polypropylene(EPP), granular activated carbon, zeolite, perlite, illite, sand, gravel has been developed. This study was conducted to verify performance and hydraulic characteristics of filter media as measures for non-point source. The experiment was carried out to evaluate applicability and variation of 4 kind of most popular filter media(EPP, GAC, Zeolite, Perlite) in headloss with elapsed time and influent flow rate and to obtain data base that could be used to establish management plan for road runoff treatment. In experiment by tap water, it showed that EPP and perlite those are floatable materials showed stable operating performance and lower headloss than the others.