• 전기학회논문지
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• 제63권6호
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• pp.727-737
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• 2014

This paper presents the design of Fuzzy PI controller that is used at BESS(Battery Energy Storage System) charging and discharging process for islanded operation in microgrid. Most of the PI controllers have fixed PI gains, but real-time updated gains are applied to PI controller using Fuzzy logic in this paper. The performances of suggested Fuzzy PI controller are simulated by PSCAD/EMTDC. As a result, output characteristics of ESS applied real-time updated gains to PI controller are faster than those of using fixed gains.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.131-134
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• 2004

Characteristics of electrodelss lamp as a load of the ballast is different compared to normal fluorescent lamp because the lamp includes the magnetics for inductive discharging process. So somewhat different modeling is necessary to make a proper power match between the lamp and ballast. Modeling of an electrodeless lamps, Endura of Osram, is presented in this paper. Simulation with a result of experiment is given for a verification of proposed model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2179-2181
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• 2005

An experimental study on the water plasma characteristics of removal efficiency for organic contaminants in dye waste water has been investigated. In this study, dielectric barrier discharging electrodes with round shape have disposed cross each other in reactor, and pulse power was supplied to between each electrodes. Its output pulse voltage range is from 0[V] to 30[kV] and output frequency range is from 100[Hz] to 2[kHz]. Using proposed system, High frequency discharge is tested in the mixed Tone(air and water) and the space distribution of streamer corona plasma is observed. In spite of the increasement of voltage and frequency, the proposed system have a stable operation characteristics. It is verified by the experimental results.

• Transactions on Electrical and Electronic Materials
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• 제17권4호
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• pp.212-216
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• 2016

A reflective electronic display that uses negatively and positively charged particles has excellent bistability, a welldefined threshold voltage, and an extremely fast response time in comparison with other reflective displays. This type of display shows images through the movement of charged particles whose motion depends on the value of q/m (charge per mass for a particle). However, the ratio q/m can easily be changed by the forces acting on the charged particles in a cell of the panel and by friction that occurs after mixing oppositely charged particles and in the particle-insertion process. In this study, we propose a method to determine the appropriate range of q/m by using the reflectivity and response time of charged particles to modify q/m. In this manner, the electrical and optical properties of reflective displays are improved.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.205-206
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• 2010

This paper presents a study on the efficiency of DC-DC converter to charge/discharge lithium battery. The losses of switching device, magnetic components, output capacitor, diode, and snubber circuit are analyzed by considering the charge/discharge characteristics of the converter. Based on the loss analyses, efficiency simulation in charging/discharging process are performed.

• KEPCO Journal on Electric Power and Energy
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• 제5권2호
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• pp.113-120
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• 2019

We have developed 1 kW-class PEMFC-battery hybrid system independently powering to the building, through the process of system design, current load characteristics analysis, power system configuration for demonstration site and performance evaluation. In order to use the fuel cell and battery as the hybrid type, a control technology for the charging/discharging decision and charging speed of the battery is required rather than using fuel cell. Also output power distribution between PEMFC and the battery is a core of energy management technology. It is confirmed that it is possible to supply independently 1kW powering the building to ensure optimal energy management through the power control experiment of the hybrid system.

• 전력전자학회논문지
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• 제18권6호
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• pp.593-600
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• 2013

The asymmetric pulsed DC reactive magnetron sputtering system is widely used for the high quality plasma sputtering process such as a thin film deposition. In asymmetric pulsed DC power supply a reverse voltage is applied to the target periodically to minimize arc discharging effect. When sputtering in the mid-frequency range (20-350 kHz), the periodic target voltage reversals suppress arc formation at the target and provide long-term process stability. Thus, high quality, defect-free coatings of these materials can now be deposited at competitive rates. In this paper, a new style asymmetric pulsed DC power supply including mid-transformer is presented. In the proposed, an energy recovery circuit is adopted to reduce the mutual inductance of the transformer. As a result, the system dynamics of the voltage control loop is increased highly and the non-linear voltage boosting effect of the conventional system is removed. This work was proved through simulation and laboratory based experimental study.

• 한국기계가공학회지
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• 제2권1호
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• pp.15-21
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• 2003

The ultrasonic polishing machine was developed to get super finishing that consist of machine part that can rotate and travel the main shaft with power 1.5kW, ultrasonic generator with frequency 20kHz. By using this machine we were investigated the characteristics of ultrasonic polishing for three different ceramics, and so could be obtained following results. First, we could be obtained the excellent surface for hard-ta-difficult cutting materials. Second, the effect of surface roughness for the feed rate could be shown that the more the feed rate Increases, the more the value of surface roughness increases. Third, owing to the characteristics being progressed brittle fracture in $Al_2O_3$ polishing with this machine, the value of surface roughness is larger than other ceramics. Forth, because the ultrasonic polishing can be smoother than the existing grinding in discharging the chips, it could be possible to improve the surface roughness about up to 15%.

• Advances in Energy Research
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• 제4권2호
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• pp.147-161
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• 2016

To start with, finding a sustainable method to produce sweet water and electricity by using renewable energies is one of the most important issues at this time. So, experimental and theoretical analysis of the performance of a closed solar powered still, which is jointed to photovoltaic cells and vacuum pump and equipped by nano plate, as the principle stage of zero discharge desalination process is investigated in this project. Major goal of this work is to reuse the concentrated brine of the Mobin petrochemical complex in order to produce potable, sweet water from effluent saline wastewater and generating electricity in the same time by using solar energy instead of discharging them to the environment. It is observed the increase in brackish water temperature increases the average daily production of solar desalination still considerably. Therefore, the nano plate and vacuum pump are added to augment the evaporation rate. The insolation rate, evaporation rate, the average brackish temperature, ambient temperature, density are investigated during a year 2013. In addition to obtain the capacity of solar powered still, the highest and lowest amount of water and electricity generation are reported during a twelvemonth (2013). Results indicate the average daily production is increased 16%, which represents 7.78 kW.h energy saving comparing with traditional solar still.

• 한국기계가공학회지
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• 제11권5호
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• pp.60-67
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• 2012

In the study, the effect grinding condition on the workpiece arithmetical average roughness(Ra) to 10 steps leading to cutting each section with the spindle rotational speed 8000rpm and feed rate 150mm/min of grinding in GC(green silicon carbide) grinding processing after heat treatment and non heat treatment of SCM415 material. Also the following conclusions were obtained analysis of stress distribution displacement and finite elements method(FEM) on assemble parts with 3+2 axis simultaneous control through grinding and gave a load 11kg on ATC arm both sides gave a load of 11kg. For the centerline average roughness(Ra) in the heat and non-heat treatment work pieces, which were appeared the most favorable in the fifth section were $0.511{\mu}m$ and $0.514{\mu}m$, that were shown in the near the straight line section was the smallest deformation of curve. In addition, the bad surface roughness appeared on the path is too long by changing angle, the more inclined depth of cut, because the chip discharging is not smoothly.