• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.601-610
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• 2020

Recently, damage caused by drought is becoming worse and worse due to the global climate change. To overcome these problems, movable-weir to control the water level has been installed instead of a fixed-weir made from concrete. On the other hand, it is difficult to operate an existing moveable-weir because of the high cost of facility management and manpower consumption. In addition, because most moveable-weirs are installed in power systems, the operating cost and the cost of connection for power systems increase when they are located in remote areas. Therefore, this paper proposes an optimal design algorithm and the evaluation algorithm of the SOC (state of charge) of a lithium-ion battery to replace an existing power supply with eco-friendly movable-power with a power supply system using PV modules and lithium-ion batteries. In addition, this study modeled a 50kW power supply system of a movable-weir using PSCAD/EMTDC S/W. The simulation results confirmed that the proposed algorithm has stable operation characteristics in an independent operation mode and interconnection operation mode and that there is the possibility of commercialization with a benefits evaluation of the eco-friendly power supply system of a movable-weir.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.109.1-109.1
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• 2011

KEPCO was operating power plants with diesel generators in 49 islands including Baekryeong-Do, and the generation capacity was about 66 MW in 2008. The cost of fuel is increasing by the international oil price inflation and continuous rise of oil price is predicted. For the stabilizing of electric power supply to the separate islands, renewable energy and fuel cell systems were considered. Hydrogen is made using renewable energy such as wind power and solar energy, and then a fuel cell system generates electricity with the stored hydrogen. Though the system efficiency is low, it is treated as the only way to secure the stable electric supply using renewable energy at this present. The analytic hierarchy process was used to select suitable candidate island for the system installation and 5 islands including Ulleung-Do were selected. Economic evaluation for the system composed of a kerosene generator, a wind power, an electrolysis, and a fuel cell system was conducted with levelized generation cost based on present value methode. As the result, the necessity of renewable energy combined generation system and micro grid composition in the candidated islands was confirmed. Henceforth, the development of an integration technology which connects micro grid to the total power grid will be needed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.427-430
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• 2001

Computers and automated manufacturing processes in industry are very susceptible to voltage sags and surges. The need for greater power reliability makes the end-users to use the uninterruptible power supply and other electronic power conditioning means to maintain the stable voltage. In this paper, a single-phase buck ac-ac converter for Custom Power Applications is presented. The presented converter uses IGBT's as switching module and maintains the stable voltage through PWM technology in spite of the input voltage sags and load rejections. In this paper, the operation characteristics of the power converter at steady state are illustrated using PSPICE simulations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.181-186
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• 2019

In order to reduce the fossil fuels consumed in conventional commercial independent diesel generators in the same environment as the island area, it is necessary to develop a photovoltaic system that will bear more than 40% of the independent system capacity. For this development, it is necessary to develop a high-capacity inverter that can improve the stability of the independent system installed in the island area and supply high-quality power to the load. In addition, the EMS power generation control system for the independent grid photovoltaic power generation system is a parallel operation power control system of the diesel generator connected with the solar power generation system. It controls the output of the diesel generator according to the load ratio and the solar power generation, A stable supply system is needed. This independent grid photovoltaic generation system can increase the solar power supply to the independent system area and increase the power stability of the independent system and further reduce the use of fossil fuel due to the ineffective power control of the independent system. It is expected that the economy will be secured early.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1239-1243
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• 2004

A novel voltage-current reference circuit for stable voltage-current applications is Proposed. Circuits for a positive and for a negative voltage-current reference are presented and are designed with commercial CMOS technology. The voltage-current reference that is stable over ambient temperature variations is an important component of most data acquisition systems. These results are verified by the HSPICE simulation $0.8{\mu}m$ parameter. As the result, the temperature dependency of output voltage and output current each is $0.57mV/^{\circ}C$, $0.11{\mu}A/^{\circ}C$ and the power dissipation is 1.8 mV on 5V supply voltage.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.214-216
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• 2005

The PAL (Pohang Accelerator Laboratory) is persuading to construct a SASE-XFEL facility (PAL XFEL) that supplies coherent X-rays. The bright and stable electron beam is essential for the PAL XEL. The electron beams has to have an emittance of 1.0 mm-mrad, a peak current of 3 kA, and a low energy spread of 1.0 MeV. In order to provide reasonably stable SASE output, the RF stability of 0.02% rms is required for both RF phase and amplitude. This is a technologically challenging issue for PAL XFEL. An inverter technology is to be applied to charge the PFN of a new modulator. Therefore, a new inverter system should provide very stable charging performances. This paper presents the development of an ultra stable klystron-modulator with an inverter power supply.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.4
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• pp.54-60
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• 2005

In a $CO_2$ inverter welding machine, stable arcs can be generated and a welding performance that is a goal of welding can be improved when stable electric power with a low voltage and a high current is supplied to a electrode that is the secondary part (output load terminal) and the base metal. For such a stable power supply, therefore, the AC arc welding machine, the thyristor welder, and the inverter welder have been developed in order according to development of the power electronics techniques. Up to now, the thyristor welding machine is still broadly used but the application volume is gradually reduced by development of the inverter welder. Because the welding performance of the inverter welder is very good and the weight and size of the welder is remarkably light and small. The final goal of this research is to develop the voltage loss compensator that is a drawback of the inverter welder and improve the welding performance using the developed compensator.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.81-89
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• 1997

In order to achieve the zero voltage regulation of the output voltage, the function control law will be used. In the previous function control law, only the proportional controller is used and the stability of the closed loop system was not analyzed. In this paper, for the realization of the control law, a new method to retrieve the low frequency component of the inductor voltage is proposed and analyzed. The large signal closed loop characteristics are alos analyzed to ensure the stable operation of the system disturbances. By using the function control law in the control system, the effect of the disturbance of the supply voltage is reduced in 93.3% for the direct dusty ration method. Also, in the effect of the disturbance of the load current, the output voltage has a logn recovery-time and is changed proportionally in the direct duty ratio method, but has stable in the function control law. Finally, the analysis shows that the disturbance of the output voltage being due to the supply voltage variation can be eliminated completely and the closed loop output voltage is insensitive to the disturbance of the load current. Therefore, it is proved that by using the function control law, the switching power supply with zero-voltage regulation output voltage can be realized.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.106-111
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• 1992

In order to achieve stable and efficient use of energy at iron and steel works, a model for the prediction of supply and demand of electric power system is developed on the basis of the information on operation and particular patterns of electric power consumption. The optimal amount of electric power to be purchased and the optimal fuel allocation for the in-house electric power plants are also obtained by a mixed-integer linear programming(MILP) and a nonlinear programming (NLP) solutions, respectively. The validity and the effectiveness of the proposed model are investigated by several illustrative examples. The simulation results show the satisfactory energy saving by the optimal solution obtained through this research.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.555-563
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• 2012

Due to the importance of energy-saving and CO2 reduction is being emphasized in the world, efforts to find a solution for the problems is increasing rapidly. In particular, the renewable energy is on understanding as a breakthrough for the protection of the environment and the economic development, so it is intensively fostered as future industries. Developed countries are already pursuing policy and technology development related with renewable energy. In this paper, we will develop MHD(Magneto Hydro Dynamics) technology to supply the commercial power that can is targeted at water pipe related with hydro power among renewable energy technologies. Kinetic energy of fluid flowing in the water pipe is converted into electric power. It allows stable power supply to the various sensors and devices on water pipe. We have performed several experiments to verify the application possibility of the developed technologies and present the result and a method of performance improvement of the technologies.