• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.547-553
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• 1998

In this paper, we composed of utility interactive pv generation system of voltage source inverter, and represented uninterrutible power supply (UPS) equipment maintaining constant voltage, using a pulse width modulation(PWM) voltage fed inverter, as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to dc side with solar cell using a photovoltaic (PV) that it was so called constant voltage charge. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.120-129
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• 1998

In this paper represented uninterruptible power sypply(UPS) equipment maintaining constant output voltage, using a pulse width modulation(PWM) voltage fed inverter, as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to DC side with solar cell using a Photovoltaic (PV) that it was so called constant voltage charge. In addition, better output waveform was generated because of PWM(pulse width Modulation) method, and it was Proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• Journal of Environmental Science International
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• v.17 no.10
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• pp.1075-1080
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• 2008

The influence of the point source inflow on the water quality variation in the downstream of Hyeongsan River was investigated. As the results of seasonal variation, the pollutant concentrations of dry season were 1.5-4 times higher than those of wet season. The increase rate of $BOD_5$, $COD_{Mn}$, T-N, T-P due to point source were ranged to $8.1\sim42.6%$, $7.3\sim41.9%$ and $17.1\sim207%$ as the inflow of P1, P2 and P3, respectively. After P1, P2 and P3 inflow, the accumulated increase rate were 64.3%, 32.6%, 93.1% and 258.9% in $BOD_5$, $COD_{Mn}$, T-N, T-P, respectively. It was found that the influence of point source inflow on the water quality in the downstream of Hyeongsan River is severe.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1271-1278
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• 2010

High-speed traction has voltage source variation because the electric power of tractions is supplied by difference traction power system according to operating section. This paper proposes the robust control maintaining constant output performance against voltage source variation for PWM converters of the high speed traction. The proposed scheme consists of feed-forward compensation for current controller by on-line calculating the rms voltage of voltage source. Total dynamic performance of high speed traction can be improved by the reduction of the output voltage ripple which is resulted from voltage source sag and variation. The superior performance and validity of the proposed scheme is proved through the simulation.

• The Plant Pathology Journal
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• v.38 no.2
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• pp.90-101
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• 2022

Pathogenicity of eight Bacillus strains to seedlings of four cotton cultivars was evaluated under greenhouse conditions. Each of the tested cultivars was individually treated with powdered inoculum of each bacterial strain. Untreated seeds were planted as control treatments in autoclaved soil. Effects of the tested strains on levels and activities of some biochemical components of the infected seedlings were also assayed. The biochemical components included total soluble sugars, total soluble proteins, total free amino acids, peroxidase, polyphenol oxidase, phenols, and lipid peroxidation. ANOVA showed that Bacillus strain (B) was a very highly significant source of variation in damping-off and dry weight. Cotton cultivar (V) was a nonsignificant source of variation in damping-off while it was a significant source of variation in dry weight. B × V interaction was a significant source of variation in damping-off and a nonsignificant source of variation in dry weight. Bacillus strain was the most important source of variation as it accounted for 59.36 and 64.99% of the explained (model) variation in damping-off and dry weight, respectively. The lack of significant correlation between levels and activities of the assayed biochemical components and incidence of damping-off clearly demonstrated that these biochemical components were not involved in the pathogenicity of the tested strains. Therefore, it was hypothesized that the pathogenicity of the tested strains could be due to the effect of cell wall degrading enzymes of pathogenic toxins. Based on the results of the present study, Bacillus strains should be considered in studying the etiology of cotton seedling damping-off.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.420-428
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• 2018

In this paper, represented uninterruptible power supply (UPS) equipment maintaining constant output voltage, the proposes a photovoltaic system constructed with a step up boosting chopper and single phase pulse width modulation (PWM) voltage source inverter. as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to DC side with solar cell using a Photovoltaic that it was so called constant voltage charge. It can be results of saving electric power, and through a normal operation of energy storage system (ESS), the system operated the LED a calling on signal changes at the airport in an efficient manner. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.356-362
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• 2015

This paper presents a current control strategy in the synchronous reference frame for a single-phase PWM converter, which ensures sinusoidal input current control under the distorted source voltage and frequency condition. Given that the distorted source voltage distorts the phase angle for PWM converter control, the input current contains the same harmonics as the source voltage. Aside from the distorted voltage, the variation in source frequency reduces the performance of input current control. To achieve sinusoidal input current control under the distorted source voltage and frequency condition, this paper proposes a compensation strategy of current reference with the distortion component extracted from the phase angle and a detection strategy of frequency variation from the output of a synchronous reference frame phase-lock loop. The experimental results confirm the validity of the proposed method under the distorted source voltage and frequency condition.

• International Journal of Quality Innovation
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• v.1 no.1
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• pp.97-105
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• 2000

In this paper, a two-section method for measuring is introduced and the variation sources of measurement process are analysed. Measuring is a special process in general process. Various variation source must be firstly decomposed so that the statistical distribution law of measuring process can be established, and then implement monitoring control of the measuring process. A special method to obtain the measuring variation is discussed, and a monitoring control technique for measuring process is studied based statistical distribution. Towards the end, we briefly introduce software design for the analysis and control of a measurement process.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.228-234
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• 2011

The goal of water quality management on stream and watershed is to focus not on discharged loads management but on a water quality management. Discharged loads management is not goal of water quality management but way for perform with total maximum daily loads management. It is necessary to estimate the relation between non-point source with stromwater runoff (NPSSR) and water quality to select a watershed where it is required to manage NPSSR for water quality improvement. To evaluate the effects of NPSSR on stream's water quality, we compare the aspects of water quality in dry and wet seasons using flow duration curve analysis based on flow rate variation data by actual surveying. In this study we attempt to quantify the variation characteristic of water quality and estimate the Inflow characteristic of pollution source with water quality and flow rate monitoring on 10 watersheds. We try to estimate water quality and flow rate by regression analysis and try again regression analysis with each high and low water quality data more than estimations. An analysis of relation between water quality and flow rate of 10 watersheds shows that the water quality of the Nonsan and the Ganggyeong streams had been polluted by NPSSR pollutants. Other eight streams were important point source more than NPSSR. It is wide variation range of $BOD_5$ also high average concentration of $BOD_5$. We have to quantify water quality variation by cv1 in wet season and cv365 in dry season with comparing the estimate of high water quality and low water quality. This method can be used to indicator for water quality variation according to flow rate.

• New & Renewable Energy
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• v.7 no.4
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• pp.30-36
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• 2011

The objective of this study is to investigate the effects of the refrigerant charge amount on the performance of a water-to-water ground source heat pump with a variation of compressor speed and the secondary fluid flow rate. The water-to-water ground source heat pump was tested by varying refrigerant charge amount from -40% to 20% of full charge. Compressor speed was changed from 30 Hz to 75 Hz and the secondary fluid flow rate was adjusted from 6 LPM to 14 LPM. For all test conditions, EWTs of an indoor heat exchanger and an outdoor heat exchanger were maintained at standard conditions of ISO 13256-2. The slope of the COP with the variation of charge amount is much steeper at undercharged conditions than that at overcharged conditions. For all compressor speed, the variation of the system performance according to charge amounts showed the similar trends. However, the optimum charge amount of the system increased a little with an increment of compressor speed. When the secondary fluid flow rate decreased, the system was optimized at higher refrigerant charge amount conditions.