• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.74-83
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• 2014

This paper proposes a study on the configuration of balancing of plant(BOP) and implementation of battery management system(BMS) functions for vanadium redox flow battery(VRFB) and propose a method consists of sensor and required design specifications BOP system configuration. And it proposes an method of the functions implementation and control algorithm of the BMS for flow battery. Functions of BMS include temperature control, the charge and discharge control, flow control, level control, state of charge(SOC) estimation and a battery protection through the sensor signal of BOP. Functions of BMS is implemented by the sensor signal, so it is recognized as a very important factor measurement accuracy of the data. Therefore, measuring a mechanical signal(flow rate, temperature, level) through the BOP test model, and the measuring an electrical signal(cell voltage, stack voltage and stack current) through the VRFB charge-discharge system and analyzes the precision of data in this paper. Also it shows a good charge-discharge test results by the SOC estimation algorithm of VRFB. Proposed BOP configuration and BMS functions implementation can be used as a reference indicator for VRFB system design.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.421-426
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• 2018

To develop a piezoelectric inkjet printhead for high-resolution and high-speed printing, we studied the characteristics of an inkjet printhead by analyzing the major design parameters. An analytical model for the inkjet printhead was established, and numerical analysis of the coupled first-order differential equation for the defined state variables was performed using state equations. To design the dimension of the inkjet printhead with a driving frequency of 100 kHz, the characteristics of the flow rate and discharge pressure of the nozzle were analyzed with respect to design variables of the flow chamber, effective sound wave velocity, driving voltage, and voltage waveform. It was predicted that the change in the height of the flow chamber does not significantly affect the Helmholtz resonance frequency and discharge speed of the nozzle. From the analysis of change in flow chamber width, it is observed that as the width of the flow chamber increases, the ejection speed greatly increases and the Helmholtz resonance frequency decreases considerably, thereby substantially affecting the performance of the inkjet printhead.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.71-77
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• 2016

The dielectric barrier discharge (DBD) has low efficiency due to about 70% input power is consumed as thermal energy in the discharge space. However, because of the usage of DBD ozone generator is easier than other methods. The DBD ozone generator has been widely applied for high concentration ozone generation in the industrial application. But, the low-capacity compact DBD ozone generator is not applied so far. Therefore, the DBD ozone generator is necessary to improve ozone production efficiency and reduce the capacity. In this paper, the stainless steel pipe inner electrode was designed with hall type and screw type to improve the ozone production yield. The manufactured two inner electrodes were experimented with normal type for comparison of the discharge characteristics and the ozone generating characteristics. As the experimental results, the discharge current effective value of designed inner electrodes with hall type and screw type are higher than the normal type, due to unequal electric field is formed at the boundary. However, the difference of designed and original electrodes is less than 0.1mA that has no effect on the discharge characteristic. On the other hand, the screw type inner electrode increased higher than original model about 7 times when the flow rate of the oxygen source gas was increased from $0.6{\ell}/min$ to $1.0{\ell}/min$ The reason was assumed by the flow rate of the raw gas through the inner electrode was became fast that has a cooling effect. The designed hall type and screw type inner electrodes have shown good performances in ozone generation and ozone production that better than normal type in the same electrode surface area.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.50 no.3
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• pp.125-129
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• 2001

ln this paper, a ozone generator using superimposition of silent discharge has been designed and manufactured. This type ozone generator is equipped with three electrodes and two gaps. Ozone is generated by superimposition of silent discharge, which is respectively come from two gaps. The maximum values of ozone concentration, ozone generation flow and ozone energy field were obtained 4,750[ppm], 2.37[g/h], 102.3[g/kWh]. Also, the result of reaction of 1,8921ppm] ozone and the sampling water from the lake, the water quality was improved from IV grade to In grade, and obtained 100[%] sterilization rate of Escherichia coli within 5.0(min).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.132-135
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• 1992

Diamond thin films by MWPECVD in methane-hydrogen mixed gas were studied, with emphasis on the investigation of the effect of discharge power and pressure. As a result, the growth rate of diamond thin films was affected by discharge power and the surface morphology of diamond thin films was affected by pressure. The growth rate of diamond films was about 1.65 ${\mu}m$/hr under the condition of MW power: 900W, pressure: 60torr, $H_2$ flow rate: 60sccm, $CH_4$ concentration: 1 % and deposition time: 5hr. The deposited diamond films were identified by SEM, XRD and Raman spectrophotometer.

• Analytical Science and Technology
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• v.5 no.2
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• pp.169-176
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• 1992

Analytical detection limits and Relative Ion Yield (RIY) by a jet type ion source glow discharge mass spectrometer(GD/MS) have been measured. With a jet type ion source, the sample loss rate for a Cu sample is 0.23 mg/min with 0.1 L/min gas flow rate and 0.11 mg/min with no gas flow rate. However, the ion intensity of Cu does not change significantly with thee variation of the gas flow rate. The RIY values obtained from the calibration curves of the six copper based standards were between 0.57 of Fe and 3.5 of Cr. The detection limits of most elements were in the range of 0.9 and 2.0 ppm when the glow discharge was operated at 4 mA, 1000V.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.421-426
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• 2005

Optimal design of serial connected PZT driven micro compressor was investigated. Modeling equations were derived using energy equation and mass conservation equation. The results show that mass flow rate was increased as number of connected micro compresses is increased. As pressure difference between suction port and discharge port in compressor group is increased, connected compressors have much more mass flow rate than single compressor. Mass flow rate is also increased as driving frequency is increased. And optimal design scale is suggested for highest efficiency or highest mass flow rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.248-254
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• 1998

In the present study the glow discharge characteristics of $CO_2$ in a parallel plate electrode system were investigated, and the decomposition properties of $CO_2$ concerned with the discharge characteristics were discussed. The results show that $CO_2$ concentration decreases with increase in discharge power and decrease in gas pressure. The maximum conversion of $CO_2$ by glow discharge was 52% under the conditions of gas pressure, 10m Torr and 290W of discharge power.

• Journal of Environmental Science International
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• v.23 no.1
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• pp.97-104
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• 2014

The sludge flotation/thickening apparatus equipped a micro-bubble generating pump was used to investigate micro-bubble generating properties on operational parameters. We evaluated micro-bubble generating properties as results to be operated the apparatus by operational parameters which are pump discharge pressure, air/water ratio(A/W ratio), air flow rate, and water flow rate. Micro-bubble generating efficiencies in pumps without recycling flow and with 50% of recycling flow was found to be very efficient on optimum A/W ratio from 1.06 to 3.62% and optimum A/W ratio from 1.05 to 4.06%, respectively. In condition of 3.6% of A/W ratio, we showed that the apparatus could be generated 36,000 ppm of micro-bubble concentration to be optimum treatment efficiency in sludge thickening process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.28-31
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• 2002

The water level fluctuation (WLF) method is a conventional method for quantifying groundwater recharge by multiplying the specific yield to the water level rise. A 2-D unconfined flow model with a time series of the recharge rate is developed. It is used for elucidating the errors of the WLF method which is implicitly based on the tank model where the horizontal flow in the saturated zone is ignored. Simulations show that the recharge estimated by the WLF method is underestimated for the observation well near the discharge boundary. This is due to the fact that the hydraulic stress resulting from the recharge is rapidly dissipating by the horizontal flow near the discharge boundary Simulations also reveal that the recharge was significantly underestimated with increase in the hydraulic conductivity and the recharge duration, and decrease in the specific yield.